Tag Archive III-V

ByGianni PRATA

Two additions to Altatech equipment lines: 10x faster ultra-thin film deposition; Doppler nano-defect inspection captures true sizing and positioning

The Orion Lightspeed™ inspection system by Altatech (a division of Soitec) pinpoints the true size and location of nano-scale defects inside compound semiconductor materials and transparent substrates

The Orion Lightspeed™ inspection system by Altatech (a division of Soitec) pinpoints the true size and location of nano-scale defects inside compound semiconductor materials and transparent substrates

Two new products from semi equipment manufacturer Altatech: one for ultra-thin film deposition, and one for searching out nano-defects. Altatech is a division of Soitec, best known in the advanced substrates community for its leadership in SOI wafers. This part of the company, however, develops highly efficient, cost-effective inspection and chemical vapor deposition (CVD) technologies used for R&D and manufacturing of semiconductors, LEDs, MEMS and photovoltaic devices.

The company’s newest inspection system, the Orion Lightspeed™, is capable of pinpointing the size and location of nano-scale defects inside compound semiconductor materials and transparent substrates (see press release here). The new system helps to ensure the quality control of high-value engineered substrates used in several fast growing markets including high-brightness LEDs, power semiconductors and 3D ICs. Inspection is based on Altatech’s patented synchronous Doppler detection™ technology, which determines the exact size and position of defects by making direct physical measurements with resolution below 100 nm. This provides true defect sizing, as opposed to other types of inspection equipment on the market that make indirect measurements using diffracted light to calculate approximate defect sizes. It handles 200mm or 300mm substrates, with throughput of 85 and 80 wafers per hour, respectively. Beta systems have already been installed at customers’ facilities and are demonstrating excellent performance. Shipments of production units are scheduled to begin in April 2015.

The new AltaCVD 3D Memory Cell™ is the latest member of Altatech’s AltaCVD line, designed to deposit ultra-thin semiconductor films that enable the manufacturing of high-density, low-power memory ICs used throughout mobile electronics (see press release here). The new system performs atomic-layer deposition 10 times faster than conventional atomic-layer deposition (ALD) systems, helping to meet global market demands for both high-volume production and cost efficiency in fabricating advanced memories. The system is currently demonstrating its unique capabilities and performance at one of Altatech’s key customers. Production units are available.

ByGianni PRATA

IntelliEPI Buys Soitec GaAs Business

Soitec, a leader in SOI wafers and other advanced substrates, recently announced the sale of its gallium arsenide (GaAs) epitaxy business (the Soitec Specialty Electronics subsidiary) to Intelligent Epitaxy Technology Inc (see press release here).  The deal follows the previous collaboration between Soitec and IntelliEPI (see press release dated December 12, 2013).

“The sale of our gallium arsenide (GaAs) epitaxy business to IntelliEPI reflects our drive to refocus Soitec’s electronics division on its key products under its five-year Soitec 2015 program,” explained Bernard Aspar, Senior Vice President and Soitec’s Communication & Power Business Unit General Manager.

“The transaction will enable IntelliEPI to widen its customer base and penetrate to several critical GaAs application markets such as automotive radar technology. It will also enable IntelliEPI to provide best-valued products and services to all its customers with expanded manufacturing capacities from its Texas, USA location,” said Yung-Chung Kao, IntelliEPI President and CEO.

 

ByAdministrator

The SOI Papers at VLSI ’14 (Part 2):

Last week we posted Part 1 of our round-up of SOI papers at the VLSI Symposia – which included the paper showing that 14nm FD-SOI should match the performance of 14nm bulk FinFETs. (If you missed Part 1, covering the three big 14nm FD-SOI and 10nm FinFET papers, click here to read it now.)

This post here gives you the abstracts of all the other papers we couldn’t fit into Part 1.  (Note that as of this posting date, the papers are not yet available on the IEEE Xplore site – but they should be shortly.)

There are in fact two symposia under the VLSI umbrella: one on technology and one on circuits. We’ll cover both here. Read on!

 

(More!) SOI Highlights from the Symposium on VLSI Technology

4.2: III-V Single Structure CMOS by Using Ultrathin Body InAs/GaSb-OI Channels on Si, M. Yokoyama et al. (U. Tokyo, NTT)

The authors propose and demonstrate the operation of single structure III-V CMOS transistors by using metal S/D ultrathin body (UTB) InAs/GaSb-on-insulator (-OI) channels on Si wafers. It is found that the CMOS operation of the InAs/GaSb-OI channel is realized by using ultrathin InAs layers, because of the quantum confinement of the InAs channel and the tight gate control. The quantum well (QW) InAs/GaSb-OI on Si structures are fabricated by using direct wafer bonding (DWB). They experimentally demonstrate both n-and p-MOSFET operation for an identical InAs/GaSb-OI transistor by choosing the appropriate thickness of InAs and GaSb channel layers. The channel mobilities of both InAs n- and GaSb p-MOSFET are found to exceed those of Si MOSFETs.

 

4.4:  High Performance InGaAs-On-Insulator MOSFETs on Si by Novel Direct Wafer Bonding Technology Applicable to Large Wafer Size Si, S. Kim et al. (U. Tokyo, IntelliEPI)

The authors present the first demonstration of InGaAs-on-insulator (-OI) MOSFETs with wafer size scalability up to Si wafer size of 300 mm and larger by a direct wafer bonding (DWB) process using InGaAs channels grown on Si donor substrates with III-V buffer layers instead of InP donor substrates. It is found that this DWB process can provide the high quality InGaAs thin films on Si. The fabricated InGaAs-OI MOSFETs have exhibited the high electron mobility of 1700 cm2/Vs and large mobility enhancement factor of 3× against Si MOSFETs.

 

6.1: Simple Gate Metal Anneal (SIGMA) Stack for FinFET Replacement Metal Gate Toward 14nm and Beyond, T. Ando et al. (IBM)

The authors demonstrate a Simple Gate Metal Anneal (SIGMA) stack for FinFET Replacement Metal Gate technology with a 14nm design rule. The SIGMA stack uses only thin TiN layers as workfunction (WF)-setting metals for CMOS integration. The SIGMA stack provides 100x PBTI lifetime improvement via band alignment engineering. Moreover, the SIGMA stack enables 9nm more gate length (Lg) scaling compared to the conventional stack with matched gate resistance due to absence of high resistivity WF-setting metal and more room for W in the gate trench. This gate stack solution opens up pathways for aggressive Lg scaling toward the 14nm node and beyond.

 

8.1: First Demonstration of Strained SiGe Nanowires TFETs with ION Beyond 700μA/μm, A. Villalon et al. (CEA-LETI, U.Udine, IMEP-LAHC, Soitec)

The authors presented for the first time high performance Nanowire (NW) Tunnel FETs (TFET) obtained with a CMOS-compatible process flow featuring compressively strained Si1-xGex (x=0, 0.2, 0.25) nanowires, Si0.7Ge0.3 Source and Drain and High-K/Metal gate. Nanowire architecture strongly improves electrostatics, while low bandgap channel (SiGe) provides increased band-to-band tunnel (BTBT) current to tackle low ON current challenges. They analyzed the impact of these improvements on TFETs and compare them to MOSFET ones. Nanowire width scaling effects on TFET devices were also investigated, showing a 1/W3 dependence of ON current ION per wire. The fabricated devices exhibit higher Ion than any previously reported TFET, with values up to 760μA/μm and average subthreshold slopes (SS) of less than 80mV/dec.

8.2: Band-to-Band Tunneling Current Enhancement Utilizing Isoelectronic Trap and its Application to TFETs, T. Mori et al. (AIST)

The authors proposed a new ON current boosting technology for TFETs utilizing an isoelectronic trap (IET), which is formed by introducing electrically inactive impurities. They  demonstrated tunneling current enhancement by 735 times in Si-based diodes and 11 times enhancement in SOI-TFETs owing to non-thermal tunneling component by the Al-N isoelectronic impurity complex. The IET technology would be a breakthrough for ON current enhancement by a few orders in magnitude in indirect-transition semiconductors such as Si and SiGe.

 

9.1: Ge CMOS: Breakthroughs of nFETs (I max=714 mA/mm, gmax=590 mS/mm) by Recessed Channel and S/D, H. Wu et al. (Purdue U.)

The authors report on a new approach to realize the Ge CMOS technology based on the recessed channel and source/drain (S/D). Both junctionless (JL) nFETs and pFETs are integrated on a common GeOI substrate. The recessed S/D process greatly improves the Ge n-contacts. A record high maximum drain current (Imax) of 714 mA/mm and trans-conductance (gmax) of 590 mS/mm, high Ion/Ioff ratio of 1×105 are archived at channel length (Lch) of 60 nm on the nFETs. Scalability studies on Ge nFETs are conducted sub-100 nm region down to 25 nm for the first time. Considering the Fermi level pining near the valence band edge of Ge, a novel hybrid CMOS structure with the inversion-mode (IM) Ge pFET and the accumulation-mode (JAM) Ge nFET is proposed.

 

13.4: Lowest Variability SOI FinFETs Having Multiple Vt by Back-Biasing, T. Matsukawa et al. (AIST)

FinFETs with an amorphous metal gate (MG) are fabricated on silicon-on-thin-buried-oxide (SOTB) wafers for realizing both low variability and tunable threshold voltage (Vt) necessary for multiple Vt solution. The FinFETs with an amorphous TaSiN MG record the lowest on-state drain cur-rent (Ion) variability (0.37 %μm) in comparison to bulk and SOI planar MOSFETs thanks to the suppressed variability of Vt (AVt=1.32 mVμm), drain induced barrier lowering (DIBL) and trans-conductance (Gm). Back-biasing through the SOTB provides excellent Vt controllability keeping the low Vt variability in contrast to Vt tuning by fin channel doping.

 

13.6: Demonstration of Ultimate CMOS based on 3D Stacked InGaAs-OI/SGOI Wire Channel MOSFETs with Independent Back Gate (Late News), T. Irisawa et al. (GNC-AIST)

An ultimate CMOS structure composed of high mobility wire channel InGaAs-OI nMOSFETs and SGOI pMOSFETs has been successfully fabricated by means of sequential 3D integration. Well behaved CMOS inverters and first demonstration of InGaAs/SiGe (Ge) dual channel CMOS ring oscillators are reported. The 21-stage CMOS ring oscillator operation was achieved at Vdd as low as 0.37 V with the help of adaptive back gate bias, VBG control.

 

17.3: Ultralow-Voltage Design and Technology of Silicon-on-Thin-Buried-Oxide (SOTB) CMOS for Highly Energy Efficient Electronics in IoT Era (Invited), S. Kamohara et al. (Low-power Electronics Association & Project, U. Electro-Communications, Keio U, Shibaura IT, Kyoto IT, U.Tokyo)

Ultralow-voltage (ULV) operation of CMOS circuits is effective for significantly reducing the power consumption of the circuits. Although operation at the minimum energy point (MEP) is effective, its slow operating speed has been an obstacle. The silicon-on-thin-buried-oxide (SOTB) CMOS is a strong candidate for ultralow-power (ULP) electronics because of its small variability and back-bias control. These advantages of SOTB CMOS enable power and performance optimization with adaptive Vth control at ULV and can achieve ULP operation with acceptably high speed and low leakage. In this paper, the authors describe their recent results on the ULV operation of the CPU, SRAM, ring oscillator, and, other lcircuits. Their 32-bit RISC CPU chip, named “Perpetuum Mobile,” has a record low energy consumption of 13.4 pJ when operating at 0.35 V and 14 MHz. Perpetuum-Mobile micro-controllers are expected to be a core building block in a huge number of electronic devices in the internet-of-things (IoT) era.

 

18.1: Direct Measurement of the Dynamic Variability of 0.120μm2 SRAM Cells in 28nm FD-SOI Technology, J. El Husseini et al. (CEA-Leti, STMicroelectronics)

The authors presented a new characterization technique successfully used to measure the dynamic variability of SRAMs at the bitcell level. This effective method easily replaces heavy simulations based on measures at transistors level. (It’s worth noting that this could save characterization/modeling costs and improve the accuracy of modeling.)  Moreover, an analytical model was proposed to explain the SRAM cell variability results. Using this model, the read failure probability after 10 years of working at operating conditions is estimated and is shown to be barely impacted by this BTI-induced variability in this FD-SOI technology.

 

18.2: Ultra-Low Voltage (0.1V) Operation of Vth Self-Adjusting MOSFET and SRAM Cell, A. Ueda et al. (U. Tokyo)

A Vth self-adjusting MOSFET consisting of floating gate is proposed and the ultra-low voltage operation of the Vth self-adjustment and SRAM cell at as low as 0.1V is successfully demonstrated.  In this device, Vth automatically decreases at on-state and increases at off-state, resulting in high Ion/Ioff ratio as well as stable SRAM operation at low Vdd. The minimum operation voltage at 0.1V is experimentally demonstrated in 6T SRAM cell with Vth self-adjusting nFETs and pFETs.

 

18.3: Systematic Study of RTN in Nanowire Transistor and Enhanced RTN by Hot Carrier Injection and Negative Bias Temperature Instability, K. Ota et al. (Toshiba)

The authors experimentally study the random telegraph noise (RTN) in nanowire transistor (NW Tr.) with various NW widths (W), lengths (L), and heights (H). Time components of RTN such as time to capture and emission are independent of NW size, while threshold voltage fluctuation by RTN was inversely proportional to the one-half power of circumference corresponding to the conventional carrier number fluctuations regardless of the side surface orientation. Hot carrier injection (HCI) and negative bias temperature instability (NBTI) induced additional carrier traps leading to the increase in the number of observed RTN. Moreover, threshold voltage fluctuation is enhanced by HCI and NBTI and increase of threshold voltage fluctuation becomes severer in narrower W.

 

SOI Highlights from the Symposium on VLSI Circuits

C19.4: A 110mW, 0.04mm2, 11GS/s 9-bit interleaved DAC in 28nm FDSOI with >50dB SFDR across Nyquist. E. Olieman et al. (U.Twente)

The authors presented an innovative nine-bit interleaved DAC (digital-to-analog converter) implemented in a 28nm FD-SOI technology. It uses two-time interleaving to suppress the effects of the main error mechanism of current-steering DACs. In addition, its clock timing can be tuned by back gate bias voltage. The DAC features an 11 GS/s sampling rate while occupying only 0.04mm2 and consuming only 110mW at a 1.0V supply voltage.

 

UTwenteC194VLSI14lowres

(Courtesy: VLSI Symposia)

A nine-bit interleaved digital-to-analog converter (DAC) from the University of Twente uses two-time interleaving to suppress the effects of the main error mechanism of current-steering DACs. The low-power device features an 11 GS/s sampling rate and occupies only 0.04mm2. From A 110mW, 0.04mm2, 11GS/s 9-bit interleaved DAC in 28nm FDSOI with >50dB SFDR across Nyquist, E. Olieman et al. (University of Twente)

 

 

C6.4: A Monolithically-Integrated Optical Transmitter and Receiver in a Zero-Change 45nm SOI Process, M. Georgas et al . (MIT, U.Colorado/Boulder)

An optical transmitter and receiver with monolithically-integrated photonic devices and circuits are demonstrated together for the first time in a commercial 45nm SOI process, without any process changes. The transmitter features an interleaved-junction carrier-depletion ring modulator and operates at 3.5Gb/s with an 8dB extinction ratio and combined circuit and device energy cost of 70fJ/bit. The optical receiver connects to an integrated SiGe detector designed for 1180nm wavelength and performs at 2.5Gb/s with 15μA sensitivity and energy cost of 220fJ/bit.

ByAdministrator

IEDM ’13 (Part 2): More SOI and Advanced Substrate Papers

SOI and other advanced substrates were the basis for dozens of excellent papers at IEDM ’13.  Last week we covered the FD-SOI papers (click here if you missed that piece). In this post, we’ll cover the other major SOI et al papers – including those on FinFETs, RF and various advanced devices.

Brief summaries, culled from the program (and some of the actual papers) follow.

 

SOI-FinFETS

9.4 2nd Generation Dual-Channel Optimization with cSiGe for 22nm HP Technology and Beyond (IBM)

This paper about performance boosters is applicable to all flavors of SOI-based devices, including FinFET, planar FD-SOI and partially-depleted SOI. At 22nm for high-performance (HP), IBM is still doing the traditional partially-depleted (PD) SOI. At 14nm, when they go to SOI-FinFETs, one of the channel stressors to boost performance is Silicon-Germanium (cSiGe). To better understand the physics, layout effects and impact of cSiGe on device performance, IBM leveraged their 22nm HP technology to do a comprehensive study. They got a 20% performance boost and 10% Short Channel Effect (SCE) improvement, and showed that this 2nd generation high-performance dual-channel process can be integrated into a manufacturable and yieldable technology, thereby providing a solid platform for introduction of SiGe FinFet technology.

 

13.5 Comprehensive study of effective current variability and MOSFET parameter correlations in 14nm multi-Fin SOI FINFETs  (GlobalFoundries, IBM)

SOI FINFETs are very attractive because of their added immunity to Vt variability due to undoped channels. However, circuit level performance also depends on the effective current (Ieff) variability. According to the advance program, “A first time rigorous experimental study of effective current (Ieff) variability in high-volume manufacturable (HVM) 14nm Silicon-On-Insulator (SOI) FINFETs is reported which identifies, threshold voltage (Vtlin), external resistance (Rext), and channel trans-conductance (Gm) as three independent sources of variation. The variability in Gm, Vtlin (AVT=1.4(n)/0.7(p) mV-μm), and Ieff exhibit a linear Pelgrom fit indicating local variations, along with non-zero intercept which suggests the presence of global variations at the wafer level. Relative contribution of Gm to Ieff variability is dominant in FINFETs with small number of fins (Nfin); however, both Gm and Rext variations dominate in large Nfin devices. Relative contribution of Vtlin remains almost independent of Nfin. Both n and p FINFETs show the above mentioned trends.”

 

20.5 Heated Ion Implantation Technology for Highly Reliable Metal-gate/High-k CMOS SOI FinFETs (AIST, Nissin Ion Equipment)

In this paper, the researchers thoroughly investigated the impact of the heated ion implantation (I/I) technology on HK/MG SOI FinFET performance and reliability, which it turns out is excellent. They demonstrated that “…the heated I/I brings perfect crystallization after annealing even in ultrathin Si channel. For the first time, it was found that the heated I/I dramatically improves the characteristics such as Ion-Ioff, Vth variability, and bias temperature instability (BTI) for both nMOS and pMOS FinFETs in comparison with conventional room temperature I/I.”

 

26.2:  Advantage of (001)/<100> oriented Channel to Biaxial and Uniaxial Strained Ge-on-Insulator pMOSFETs with NiGe S/D (AIST)

In this paper about boosters in fully-depleted planar SOI and GeOI based devices, the researchers “compared current drivability between (001)/<100> and (001)/<110> strained Ge-on-insulator pMOSFETs under biaxial and uniaxial stress.” They experimentally demonstrated for the first time that in short channel (Lg < 100 nm) devices, <100> channels exhibit higher drive current than <110> channels under both the biaxial- and the uniaxial stress, in spite of the disadvantage in mobility, although this is not the case with longer channel devices. The advantage is attributable to higher drift velocity in high electric field along the direction and becomes more significant for shorter Lg devices. The strained-Ge (001)/<100> channel MOSFET have a potential to serve as pFET of ultimately scaled future CMOS.

 

33.1 Simulation Based Transistor-SRAM Co-Design in the Presence of Statistical Variability and Reliability (Invited) (U. Glasgow, GSS, IBM)

With ever-reducing design cycles and time-to-market, design teams need early delivery of a reliable PDK before mature silicon data becomes available. This paper shows that the GSS ‘atomistic’ simulator GARAND used in this study provides accurate prediction of transistor characteristics, performance and variability at the early stages of new technology development and can serve as a reliable source for PDK development of emerging technologies, such as SOI FinFET.  Specifically, the authors report on, “…a systematic simulation study of the impact of process and statistical variability and reliability on SRAM cell design in a 14nm technology node SOI FinFET transistors. A comprehensive statistical compact modeling strategy is developed for early delivery of a reliable PDK, which enables TCAD- based transistor-SRAM co-design and path finding for emerging technology nodes.” 

 

RF-SOI

1.3: Smart Mobile SoC Driving the Semiconductor Industry: Technology Trend, Challenges and Opportunities (Qualcomm)

In this plenary presentation, Geoffry Yeap, VP of Technology at Qualcomm gave a perspective on state of the art mobile SoCs and RF/analog technologies for RF SOCs. The challenge, he said in his paper, is “…lower power for days of active use”. He cited the backgate for asymmetric gate operation and dynamic Vt control, noting that FinFETs lack an easy way to access the back gates. “This is especially crucial when Vdd continues to scale lower to a point that there is just not sufficient (Vg-Vt) to yield meaningful drive current,” he continued. While he sees FD-SOI “very attractive”, he is concerned about the ecosystem, capacity and starting wafer price.

With respect to RF-SOI, the summary of his talk in the program stated, “Cost/power reduction and unique product capability are enabled by RF front end integration of power amplifiers, antenna switches/tuners and power envelope tracker through a cost-effective RF-SOI instead of the traditional GaAs.”

 

Advanced Devices

Post-FinFETs, one of the next-generation device architectures being heavily investigated now is  gate-all-around (GAA). While FinFETs have gate material on three sides, in GAA devices the gate completely surrounds the channel. A popular fabrication technique is to build them around a nanowire, often on an SOI substrate.

4.4 Demonstration of Improved Transient Response of Inverters with Steep Slope Strained Si NW TFETs by Reduction of TAT with Pulsed I-V and NW Scaling  (Forschungszentrum Jülich, U. Udine, Soitec)

This is a paper about a strained Si (sSi) nanowire array Tunnel FETs (TFETs). The researchers demonstrated that scaled gate all around (GAA) strained Si (sSi) nanowire array (NW) Tunnel FETs (TFETs) allow steep slope switching with remarkable high ION due to optimized tunneling junctions. Very steep tunneling junctions have been achieved by implantations into silicide (IIS) and dopant segregation (DS) with epitaxial Ni(AlxSi1-x)2 source and drain. The low temperature and pulse measurements demonstrate steep slope TFETs with very high I60 as TAT is suppressed. GAA NW TFETs seem less vulnerable to trap assisted tunneling (TAT). Time response analysis of complementary-TFET inverters demonstrated experimentally for the first time that device scaling and improved electrostatics yields to faster time response.

 

IBM_IEDMBangsaruntip20.2Fig.4

(image courtesy: IBM, IEEE/IEDM)

20.2 Density Scaling with Gate-All-Around Silicon Nanowire MOSFETs for the 10 nm Node and Beyond (IBM)

Record Silicon Nanowire MOSFETs: IBM researchers described a silicon nanowire (SiNW)-based MOSFET fabrication process that produced gate-all-around (GAA) SiNW devices at sizes compatible with the scaling needs of 10-nm CMOS technology. They built a range of GAA SiNW MOSFETs, some of which featured an incredible 30-nm SiNW pitch (the spacing between adjacent nanowires) with a gate pitch of 60 nm. Devices with a 90-nm gate pitch demonstrated the highest performance ever reported for a SiNW device at a gate pitch below 100 nm— peak/saturation current of 400/976 µA/µm, respectively, at 1 V. Although this work focused on NFETs, the researchers say the same fabrication techniques can be used to produce PFETs as well, opening the door to a potential ultra-dense, high-performance CMOS technology.

 

 

26.4 FDSOI Nanowires: An Opportunity for Hybrid Circuit with Field Effect and Single Electron Transistors (Invited) (Leti)

This paper is about nanowires and single electron transistors (SET).  As indicated in the  program, “When FDSOI nanowires width is scaled down to 5nm, the nanowires can encounter a dramatic transition to single electron transistor characteristics. This enables the first room temperature demonstration of hybrid SET-FET circuits thus paving the way for new logic paradigms based on SETs. Further scaling would rely on deterministic dopant positioning. We have also shown that Si based electron pumps using tunable barriers based on FETs are promising candidates to realize the quantum definition of the Ampere.”

 

26.6 Asymmetrically Strained High Performance Germanium Gate-All-Around Nanowire p-FETs Featuring 3.5 nm Wire Width and Contractable Phase Change Liner Stressor (Ge2Sb2Te5) (National U. Singapore, Soitec)

In this paper about GAA and nanowires, the researchers report “…the first demonstration of germanium (Ge) GAA nanowire (NW) p-FETs integrated with a contractable liner stressor. High performance GAA NW p-FET featuring the smallest wire width WNW of ~3.5 nm was fabricated. Peak intrinsic Gm of 581 μS/μm and SS of 125 mV/dec was demonstrated. When the Ge NW p-FETs were integrated with the phase change material Ge2Sb2Te5 (GST) as a liner stressor, the high asymmetric strain was induced in the channel to boost the hole mobility, leading to ~95% intrinsic Gm,lin and ~34% Gm,sat enhancement. Strain and mobility simulations show good scalability of GST liner stressor and great potential for hole mobility enhancement.”

 

III-V, More Than Moore and Other Interesting Topics

28.5 More than Moore: III-V Devices and Si CMOS Get It Together (Invited) (Raytheon)

This is continuation of a major ongoing III-V and CMOS  integration project that Raytheon et al wrote about in ASN five years ago (see article here).  As noted in the IEDM program, the authors “…summarize results on the successful integration of III-V electronic devices with Si CMOS on a common silicon substrate using a fabrication process similar to SiGe BiCMOS. The heterogeneous integration of III-V devices with Si CMOS enables a new class of high performance, ‘digitally assisted’, mixed signal and RF ICs.

 

31.1 Technology Downscaling Worsening Radiation Effects in Bulk: SOI to the Rescue (Invited) (ST)

In this paper, the authors explore the reliability issues faced by the next generation of devices.  As they note in the description of the paper in the program, “Extrinsic atmospheric radiations are today as important to IC reliability as intrinsic failure modes. More and more industry segments are impacted. Sub-40nm downscaling has a profound impact on the Soft Error Rate (SER) of BULK technologies. The enhanced resilience of latest SOI technologies will fortunately help leveraging existing robust design solutions.”

 

13.3 A Multi-Wavelength 3D-Compatible Silicon Photonics Platform on 300mm SOI Wafers for 25Gb/s Applications (ST, Luxtera)

Luxtera’s work on Silicon Photonics and now products based on integrated optical communications has been covered here at ASN for years. In this paper Luxtera and ST (which now is Luxtera’s manufacturing partner) present a low-cost 300mm Silicon Photonics platform for 25Gb/s application compatible with 3D integration and featuring competitive optical passive and active performance. This platform aims at industrialization and offering to system designers a wide choice of electronic IC, targeting markets applications in the field of Active optical cables, optical Modules, Backplanes and Silicon  Photonics Interposer.

 

Irisawa (2.2) Fig.9

The graph above shows the high electron mobility of Triangular MOSFETs with InGaAs Channels. (Image courtesy: AIST, IEEE/IEDM) 

 

2.2. High Electron Mobility Triangular InGaAs-OI nMOSFETs with (111)B Side Surfaces Formed by MOVPE Growth on Narrow Fin Structures (AIST, Sumitomo, Tokyo Institute of Technology)

InGaAs is a promising channel material for high-performance, ultra-low-power n-MOSFETs because of its high electron mobility, but multiple-gate architectures are required to make the most of it, because multiple gates offer better control of electrostatics. In addition, it is difficult to integrate highly crystalline InGaAs with silicon, so having multiple gates offers the opportunity to take advantage of the optimum crystal facet of the material for integration. A research team led by Japan’s AIST built triangular InGaAs-on-insulator nMOSFETs with smooth side surfaces along the <111>B crystal facet and with bottom widths as narrow as 30 nm, using a metalorganic vapor phase epitaxy (MOVPE) growth technique. The devices demonstrated a high on-current of 930 μA/μm at a 300-nm gate length, showing they have great potential for ultra-low power and high performance CMOS applications.

 

16.4. High performance sub-20-nm-channel-length extremely-thin body InAs-on-insulator Tri-gate MOSFETs with high short channel effect immunity and Vth tenability (Sumitomo, Tokyo Institute of Technology)

This III-V paper investigates the effects of vertical scaling and the tri-gate structure on electrical properties of extremely-thin-body (ETB) InAs-on-insulator (-OI) MOSFETs. “It was found that Tbody scaling provides better SCEs control, whereas Tbody scaling causes μfluctuation reduction. To achieve better SCEs control, Tchannel scaling is more favorable than Tbuffer scaling, indicating QW channel structure with MOS interface buffer is essential in InAs-OI MOSFETs. Also, the Tri-gate ETB InAs-OI MOSFETs shows significant improvement of short channel effects (SCEs) control with small effective mobility (μeff) reduction. As a result, we have successfully fabricated sub-20-nm-Lch InAs-OI MOSFETs with good electrostatic with S.S. of 84 mV/dec, DIBL of 22 mV/V, and high transconductance (Gm) of 1.64 mS/μm. Furthermore, we have demonstrated wide-range threshold voltage (Vth) tunability in Tri-gate InAs-OI MOSFETs through back bias voltage (VB) control. These results strongly suggest that the Tri-gate ETB III-V-OI structure is very promising scaled devices on the Si platform to simultaneously satisfy high performance high SCE immunity and Vth tunability.”

11.1 A Flexible Ultra-Thin-Body SOI Single-Photon Avalanche Diode (TU Delft)

This is a paper on flexible electronics for display and imaging systems. “The world’s first flexible ultra-thin-body SOI single-photon avalanche diode (SPAD) is reported by device layer transfer to plastic with peak PDP at 11%, DCR around 20kHz and negligible after pulsing and cross-talk. It compares favorably with CMOS SPADs while it can operate both in FSI and BSI with 10mm bend diameter,” say the researchers.

 

11.7 Local Transfer of Single-Crystalline Silicon (100) Layer by Meniscus Force and Its Application to High-Performance MOSFET Fabrication on Glass Substrate (Hiroshima U.)

In this is a paper on flexible electronics for display and imaging systems, the researchers “…propose a novel low-temperature local layer transfer technique using meniscus force. Local transfer of the thermally-oxidized SOI layer to glass was carried out without any problem. The n-channel MOSFET fabricated on glass using the SOI layer showed very high mobility of 742 cm2V-1s-1, low threshold voltage of 1.5 V.  These results suggest that the proposed (meniscus force-mediated layer transfer) technique (MLT) and MOSFET fabrication process opens up a new field of silicon applications that is independent of scaling.”

 

Note: the papers themselves are typically available through the IEEE Xplore Digital Libary within a few months of the conference.

 

Special thanks to Mariam Sadaka and Bich-Yen Nguyen of Soitec for their help and guidance in compiling this post.

ByGianni PRATA

Soitec, IntelliEPI Sign Agreement on GaAs Wafers, Supply Chain

Advanced substrate leader Soitec and Intelligent Epitaxy Technology, Inc. (IntelliEPI, Taiwan) a leader in InP, GaAs, and GaSb epi wafers, have signed a collaborative agreement to better serve the GaAs market (press release here).

“We are delighted to announce the license of our technology leading to a second source for our products for our key GaAs customers ,” said Bernard Aspar, Senior Vice President and Soitec’s Communication & Power Business Unit General Manager.

“This collaborative agreement will reinforce our GaAs technology and product know-how while, at the same time, offering Soitec’s customers supply-chain security,” said Yung-Chung Kao, IntelliEPI President and CEO.

Gallium arsenide (GaAs), a III-V semiconductor, is used in the manufacture of devices such as microwave frequency ICs, monolithic microwave ICs, infrared light-emitting diodes, laser diodes, solar cells and optical windows. GaAs is often used as a substrate material for the epitaxial growth of other III-V semiconductors including InGaAs and GaInNAs.

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IP Value Starts at the Substrate Level

If you say “IP” in the chip business, everyone thinks of cores and design. But in fact, the importance of intellectual property for chips can extend right down to the substrate level.

Engineered, advanced wafer substrates open new doors for designers. For example, Soitec recently announcement that we are licensing some of our Smart Stacking™ generic bonding IP related to back-side illumination (BSI)  in image sensors to TSMC. This is a clear testament to the value of IP starting at the substrate level. But in fact, TSMC is not the first company licensing our portfolio for BSI: ST took a license for BSI a few years ago.

Soitec is known throughout the industry for our Smart CutTM technology, the enabler of the silicon-on-insulator (SOI) wafer revolution. Most of today’s industry-leading SOI wafers destined for chip manufacturing are made by wafer suppliers using the Smart Cut layer transfer technology. The Smart Cut technology is also behind the development of new families of standard and custom engineered wafers.

In fact, Soitec’s IP portfolio extends to over 3000 patents covering over 600 inventions, and every year, we add about 350 more patents.  This gives us what is arguably the most complete advanced substrate engineering portfolio in the world.

smart-stacking

So when speaking of Soitec’s expertise, we might think first of SOI wafers, but in fact, such IP is generic. It can be used as building blocks in leading-edge microelectronic products, applied to an array of materials covering a wide realm of applications.

For example, Smart Cut™ technology is now being leveraged by Sumitomo Electric to produce GaN substrates for high-performance LED lighting applications. Following the announcement of last year, Sumitomo is now industrializing the product and investing in Smart Cut technology.

In the case of Soitec’s Smart Stacking™ generic bonding technology, one of the earliest applications was indeed BSI image sensors, to help manufacturers to deliver increased sensitivity and smaller pixel size. But Smart Stacking will also be leveraged to dramatically improve the performance of RF products, opening new doors to future RF and 3D-integration applications.

One example of how effective our IP policy is came about in 1997 when we contracted with  Shin-Etsu Handotai Co., Ltd (SEH) of Japan for SOI manufacturing using our Smart Cut technology. The manufacturing agreement helped establish SOI products made with Smart Cut technology as the global standard.

Last year, Soitec and SEH (which is the world leader in the manufacturing of silicon wafers) announced a Smart Cut™ licensing extension and expanded technology cooperation agreement. The new partnership includes an extended 10-year licensing agreement between the two companies and establishes a new level of joint technology cooperation. It will facilitate the development and wafer supply of SOI wafers to meet major market opportunities such as SOI for RF devices, FinFETs on SOI and FD-SOI.

The agreement expands the scope of the partnership between Soitec and SEH, including cross-licensing Smart Cut related patents between the two companies. SEH will now also be able to extend its Smart Cut manufacturing capabilities to other materials, a trend commonly referred to as Silicon on Anything or SOA (any material on top of which there is a thin film of plain silicon), thereby further expanding the scope of applications.

Soitec’s expertise also extends to the domain of III-V epitaxy, which is leveraged in substrates for applications like RF, power, and lighting.

Beyond microelectronics, we are leveraging and expanding our innovation portfolio in energy markets. For example, earlier this year we announced the industry’s first four-junction solar cell for concentrator photovoltaic systems. We leverage both our proprietary semiconductor-bonding (Smart Stacking™) and layer-transfer (Smart Cut™) technologies to successfully stack non-lattice-matched materials while also raising the possibility of re-using expensive materials. These cells have recently reached efficiency of 44.7%, setting the world record.

The Soitec IP portfolio now represents over 20 years of successful innovation at the substrate level.   We invest around 10% of our revenue in R&D to develop and perfect breakthrough materials technologies. Our R&D teams work closely with manufacturers, as well as with laboratories such as CEA-Leti and the Fraunhofer Institute for Solar Energy Systems. We also take full advantage of the high-tech resources available in and around all of our locations worldwide.

In short, the innovations found in our substrate engineering IP portfolio are at the heart of how we lead, grow and maximize value through incremental and breakthrough solutions for the electronics and energy industries.

ByAdele Hars

Which wafers for energy-efficient, fully-depleted transistor technologies?

To drive the competitiveness of PCs, smartphones and other leading-edge devices, the electronics industry has relied for decades on the continued miniaturization of the multitude of transistors integrated in the chips at the heart of those products. However, at the tiny dimensions transistors are reaching today, conventional technology is becoming ineffective to satisfactorily combine higher transistor density, meaningful performance gains and low power consumption.

To continue scaling CMOS technology, new approaches are needed and the industry is turning to ultra-thin body, “fully depleted” (FD) transistors. These may retain a planar architecture (Fig. 1b) or go tri-dimensional (Fig.1c), in which case current flows in vertical ‘fins’ of silicon.

In both cases, in contrast with traditional technology, the current between source and drain is only allowed to flow through a very thin silicon region, defined by the geometry of the transistor. In addition, such transistors can eliminate or alleviate the need for implanting “dopant” atoms into their channel.

The physics of FD transistors allows their behavior to be greatly improved – making it possible to continue creating more complex chips with better performance and, most importantly, with power consumption kept under tight control.

FD transistors

Figure 1: Contrary to conventional CMOS (a), with planar FD (b) and tri-dimensional FD (a.k.a. FinFET) (c), the current is confined within a thin layer of silicon. [notional diagrams – not to scale]

The semiconductor industry is introducing planar FD (also referred to as FD-SOI) starting at the 28nm node, with first IC product samples scheduled for the end of 2012. Tri-dimensional FD or FinFET, on the other hand, is expected below 20nm in foundries.

Wafers for fully-depleted technology

With FD technology, either planar or tri-dimensional, the transistors are either necessarily or advantageously fabricated on innovative silicon-on-insulator (SOI) starting wafers. These wafers consist of a very thin layer of crystalline silicon, separated from a silicon base by a high-quality (and optionally ultra-thin) oxide. Soitec’s Smart CutTM technology is used to produce them and is licensed to third-parties to ensure multi-sourcing options.

Top silicon and buried oxide requirements (thickness, uniformity, etc.) are different for the planar and FinFET implementations of FD transistors. Two different wafer product lines are available to serve the needs of these two technology flavors.

FD-2D – An early and evolutionary path to fully-depleted technology

Planar FD technology puts tight requirements upon starting wafers to deliver all its benefits: for example, top silicon layer thickness must be uniform to just a few Angstroms. Today, Soitec’s FD-2D product line meets these needs in a cost-effective way and makes planar FD technology a reality.

Cross-section of a planar FD transistor fabricated on an FD-2D wafer

Figure 2: Cross-section of a planar FD transistor fabricated on an FD-2D wafer [notional – not to scale]

Figure 2 outlines the structure of a transistor fabricated from an FD-2D wafer. For the 28nm technology node, the buried oxide thickness has been set to 25nm; the ultra-thin top silicon allows fabrication of transistors with 5nm to 8nm silicon under the gate. Future generations can leverage even thinner buried oxide layers, contributing to making this technology scalable to subsequent nodes.

By enabling a planar implementation of fully depleted technology, these wafers offer the opportunity to access the benefits of FD today – there is no need to anxiously await FinFET and the 16nm/14nm technology node. Adopters of planar FD are announcing very substantial performance and leakage gains as well as impressive improvements of energy efficiency, along with exceptional performance maintained at very low power supply [Ref.1-3].

Owing to the great compatibility of planar FD with conventional CMOS, designers retain the flows and tools they would use with the latter. Furthermore, chip manufacturers use the same production lines as well as extremely similar process steps. Finally, different studies indicate that the cost of ownership of chips based on planar FD is extremely competitive compared to any alternative.

FinFET – Transition facilitated by innovative FD-3D wafers

A FinFET transistor consists of one or several fins of silicon, electrically isolated from the substrate, around which the gate wraps.

FinFET on bulk silicon wafer

Fig. 3a: FinFET on bulk silicon wafer (one fin shown) [notional – not to scale]

One solution (Figure 3a) to manufacture FinFETs consists of starting from a traditional bulk silicon wafer and completely handling fin creation and isolation through the CMOS process.

FinFET on FD-3D wafer

Fig. 3b: FinFET on FD-3D wafer (one fin shown) [notional, not to scale]

The alternative (Figure 3b) is to start from a “FinFET-friendly” wafer such as Soitec’s FD-3D, which pre-defines some of the fin characteristics and, with its buried oxide, natively embeds the electrical isolation, thus simplifying the CMOS process.

Specifically [Ref. 4-5], FD-3D wafers help obtain clearly defined and reproducible fin height and width, consistent alignment of gate, source, drain and channel, and provide optimal isolation of each fin.  In addition, it is possible to implement undoped fins if desired – thus cutting variability related to random dopant fluctuations.

Overall, and especially as dimensions will continue to shrink beyond the 16nm node, FD-3D wafers offer to facilitate control over key parameters of FinFETs as well as simplify the fabrication process. They represent an opportunity for chipmakers to make the most of FinFET technology in terms of power/performance ratio and leakage power at chip level. They are also a worthwhile proposition to reduce the industrialization challenges and optimize the total cost of ownership.

Longer term

Looking beyond the 10nm node, technology based on germanium and III-V compounds is being actively researched. In parallel, the transition of leading-edge chip production to 450mm diameter wafers is expected for the end of this decade.

In this context, the Smart Cut™ layer transfer technology for manufacturing innovative wafers may again prove extremely valuable by enabling independent control over various optimization knobs. For example, transferring a thin layer of high-quality, optimized III-V material onto a low-cost handle wafer (silicon or other), with an optimized interfacing layer, could be an interesting option.

Conclusion

Fully depleted silicon technology is coming. The question is how fast and how easily this transition can be accomplished: innovative wafers provide part of the answer.

With FD-2D, they enable a planar implementation, providing the semiconductor ecosystem with an early and low-risk path towards optimal performance and power efficiency across all use cases, as soon as the 28nm node.

With FD-3D, they can help efficiently address some key challenges of FinFET technology and make the most of it.

Looking further ahead, the Smart CutTM technology will continue to simplify the implementation of the next silicon technology breakthroughs.
———-

References

[Ref.1]    White Paper, “Planar fully depleted silicon technology to design competitive SOC at 28nm and beyond”, STMicroelectronics –  http://www.soiconsortium.org/about-soi/white-papers.php

[Ref.2]    ST Ericsson Technology Blog, May 2012: “FD-SOI: A process booster for ST-Ericsson’s next generation NovaThor – Part 2”,  http://blog.stericsson.com/blog/2012/05/st-ericsson-general/fd-soi-a-process-booster-for-st-ericssons-next-generation-novathor-%E2%80%93-part-2-2/

[Ref.3]    “MWC ST-Ericsson Media & Analyst Briefing”, February, 2012 –  http://www.stericsson.com/investors/Analyst-Event-Presentation-MWC-12.pdf

[Ref.4]    « SOI Value in IBM Silicon Technology », Oct.2011 – http://www.gsaglobal.org/3dic/docs/20111019_IBM_SOI_Value_GSA.pdf 

[Ref.5]    “SOI versus bulk-silicon nanoscale FinFETs”, Jerry G.Fossum et al., SSE Volume 54, Issue 2, Feb. 2010.

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Industry’s First InP-based HBT on Silicon

Advanced engineered substrates are a key to the Raytheon-led DARPA COSMOS project to integrate compound semiconductors and silicon CMOS on a single chip.

In what we believe to be an industry first, a Raytheon Company-led team has demonstrated the industry’s first Indium Phosphide (InP)-based heterojunction bipolar transistor (HBT) fabricated on a silicon wafer. HBTs are high-mobility, compound semiconductor (CS) transistors used primarily in RF and radar applications.
The team developed a process for directly growing a CS on a uniquely engineered silicon substrate. This innovation provides a technical approach that is creating a new class of high-performance circuits integrating CS and silicon-based CMOS on a single chip. It starts with a single wafer to enable more affordable military applications. Read More

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KORRIGAN Initiative Federates European GaN Efforts

Systems houses and research labs from seven European nations are working together on GaN HEMT technology for critical defense applications.

 

Defense radar and communication systems as well as wireless communication systems have a drastic need for increased RF performance and high-power, high-efficiency, high-linearity and low-cost monolithic amplifiers operating in the 1–40 GHz frequency range. Read More

ByGianni PRATA

OPTIMUM

Financing approved for new III-V program

The first phase of OPTIMUM, a new III-V research project lead by Thales Communications France (TCF) and partners UMS, OMMIC and Picogiga International, has recently been approved and financed. There are four sub-sections within the pro-ject. The first focuses on innovative III-V materials and technologies, in particular the optimization of GaAs substrates and the use of Smart Cut technology in future materials such as GaN and InP. Other sections focus on basic technologies such as packaging, as well as components and applications. With synergies established between the major players, the consortium expects to facilitate an expanded, world-class industrial and research pole of excellence in III-V based microelectronics and optoelectronics for the greater Paris region. •