Tag Archive UTBOX

Wafer Leaders Extend Basis for Global SOI Supply

Soitec Shin-Etsu

It’s a bright green light from the world leaders in SOI wafer capacity. Soitec, the world leader in SOI wafer production, and long-time partner Shin-Etsu Handatai (SEH), the world’s biggest producer of silicon wafers, have extended their licensing agreement and expanded their technology cooperation.

SEH is a $12.7 billion company, supplying over 20% of the world’s bulk silicon wafers. SEH’s relationship with Soitec goes way back: they were one of the original corporate investors back in 1997, and the first to license Soitec’s Smart CutTM technology for manufacturing SOI wafers.

With its 300mm SOI wafer production fabs in France and Singapore, Soitec has an expandable installed industrial base of two million wafers per year.

As Horacio Mendez, Executive Direct of the SOI Consortium told ASN, “This is a very significant announcement. The substrate supply chain is fully engaged: we have multiple independent suppliers that can clearly meet the market demands for all key sectors, including mobile devices. As the advanced technology nodes ramp, the wafer production is in place; and very importantly, the capacity is expandable to provide maximum flexibility to customers.”

SEH has been manufacturing standard SOI wafers using Smart Cut technology for years. And last year, the company said it had completed development of its ultra-thin BOX (aka UTB — the wafers used for planar FD-SOI) substrates. Nobuo Katsuoka, director of the SOI program at SEH, recently told Semiconductor Manufacturing & Design, “SEH is delighted to deliver the products on request.”

Wafers for FD-SOI (a “planar” “2D” technology) have Angstrom-level uniformity in their ultra-thin layers – so it’s excellent news that the the industry’s two leaders are both supply sources.

SOI wafers for FinFETs (a “vertical” or “3D” technology, for which the top silicon and insulating BOX layer don’t have to be ultra-ultra-thin) have also long been available from Soitec, SEH and other sources.

With respect to this announcement, SEH’s Katsuoka said, “We are very excited about the business opportunities for SOI products, and we look forward to working with Soitec to extend the global supply chain for new products, such as FD-SOI and SOI for FinFETs, which are showing potential benefits in mobile and embedded applications. Our relationship with Soitec has been a very positive and fruitful one, and we are excited to extend that collaboration. The unique features of Smart Cut will enable our two companies to jointly improve global output for existing and new SOI products.”

As Steve Longoria, SVP of WW Business Development at Soitec, told ASN, “The wafer is the front end of the manufacturing process. This announcement is a proof point of new energy for robust, multi-source supply for impending high-volume demand.”

Soitec SOI wafers

Beyond logic

The newly announced Soitec-SEH agreement also extends the companies’ commitment to wafers for a broad-range of areas. For example, there are major market opportunities in SOI for RF devices, power, MEMS/sensors, photonics and more.

The agreement also extends to R&D for technologies of the next wave. We might think of Smart Cut as an SOI technology, but in fact it’s really a manufacturing technology that can be applied to a huge range of wafer materials. As a result of the extended agreement, SEH will continue to use Soitec’s industry-defining Smart Cut technology to manufacture SOI wafers, and now will 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), which will allow SEH to further expand its scope of applications.

So with an abundance of opportunities, a robust multi-source supply chain for the front end of the chip manufacturing process, top-quality wafers that enable savings and efficiencies – in short, better end-user value – it’s all systems go for high-volume demand.

Soitec Smart Cut

This illustration shows how Smart Cut, Soitec’s proprietary engineered wafer technology, works. The industry standard, this revolutionary wafer bonding and layer splitting processes makes it possible to transfer a thin layer of material from a donor substrate to another substrate, overcoming physical limitations and changing the face of the substrate industry. The Smart Cut technology was originally developed by the CEA-Leti. Soitec holds exclusive exploitation of CEA-Leti rights into the Smart Cut technology, including the right to sublicense to SEH. The technology was made viable for SOI high-volume commercial production by Soitec, and is now protected by more than 3,000 patents owned or controlled by Soitec.

FDSOI Processes are Cost Competitive with Bulk

A new study compares processes for the 20/22nm generation at a typical foundry.

Silicon On Insulator (SOI) has been in use for state-of-the-art integrated circuit (IC) manufacturing since IBM first championed the technology in the mid-nineties. SOI offers process technologists the option of reducing power or improving performance for a given process node.

As process technology has continued to advance it has become practical to manufacture SOI wafers with silicon layers that are thin enough for  Fully Depleted SOI (FDSOI).  Also referred to as Extremely Thin SOI (ETSOI), FDSOI processes offer process technologists the opportunity to significantly simplify the process of manufacturing an IC.

IC Knowledge, the world leader in IC cost and economics was retained by Soitec, the world leader in SOI wafer manufacturing, to compare the cost of a FDSOI process versus a Bulk process for 22nm/20nm foundry logic processes.

Threshold voltages

One of the challenges of state-of-the-art foundry processes is providing the multiple threshold voltages required for power management and performance. At a minimum an additional threshold voltage requires two threshold adjust masks and associated implants.

As process geometries have shrunk additional threshold voltages may also require tailoring of source/drain (S/D) extension and halo implants and even S/D contact implants (both extension/halo and contacts each require multiple implants to fabricate).

The result is a single threshold voltage can require up to five masks and fifteen implants.

FDSOI on the other hand can provide multiple threshold voltages by alternative means (including the option to shift the threshold voltage by actively controlling the biasing of the back gate),  eliminating the need for threshold adjust masks and implants entirely.

Process simplification

An FDSOI foundry process with eight metal levels and three threshold voltages can be fabricated with up to fifteen less masking steps and forty-eight fewer implants than a similar bulk process. The resulting process simplification was found to more than offset the higher cost of the starting SOI substrate and result in a cost competitive process versus bulk with better performance.

As processes scale down to 22nm/20nm and beyond standard bulk process transistors can no longer be scaled down without exhibiting unacceptable leakage properties. Techniques such as FDSOI offer better control of the transistor channel and far lower leakage making them a viable technical solution to leakage problems. As has been shown in this study FDSOI also offers an economically viable solution.

In conclusion FDSOI processes offer sufficient process simplification to offset the additional cost of the starting SOI substrate and be cost competitive with bulk processes.

Note: the full FD-SOI cost report is available as a free download from IC Knowledge.

SOI at IEDM 2010

The 2010 IEEE International Electron Devices Meeting (IEDM) was held December 6-8, 2010 in San Francisco. The IEDM continues to be the world’s premier venue for presenting the latest breakthroughs and the broadest and best technical information in electronic device technologies.

Here are summaries of key papers referencing work on SOI or other advanced substrates.

(Note: at the time of this posting, the papers are not yet available from the  IEEE Xplore website.  However, many are available from the Advanced Silicon Device and Process Lab at the National Taiwan University.)


Paper #1.2: Energy Efficiency Enabled by Power Electronics
Arunjai Mittal (Infineon)

In particular, see section 4, where the author addresses the huge energy savings that can be realized using variable speed motors. Infineon’s driver ICs (which take a logic signal output from a microcontroller chip in the control system, and provide the appropriate current and voltage to turn power devices on and off) are built on SOI. (See Infineon’s article in ASN7. Infineon and LS Industrial Systems started a JV in 2009 called the LS Power Semitech Co., which leverages this technology.)


#2.6: Engineered Substrates and 3D Integration Technology Based on Direct Bonding for Future More Moore and More than Moore Integrated Devices (Invited)

L. Clavelier, C. Deguet, L. Di Cioccio, E. Augendre, A. Brugere, P. Gueguen, Y Le Tiec, H. Moriceau, M. Rabarot, T. Signamarcheix, J. Widiez, O. Faynot, F. Andrieu, O. Weber, C. Le Royer, P. Batude, L. Hutin, J.F. Damlencourt, S. Deleonibus, E. Defaÿ, (CEA/LETI Minatec)

This paper deals with new generations of substrates and 3D integration techniques, based on direct bonding techniques, enabling future devices in the More Moore and in the More than Moore areas.


#3.2 : Planar Fully Depleted SOI Technology: A Powerful Architecture for the 20nm Node and Beyond (Invited)

O. Faynot, F. Andrieu, O. Weber, C. Fenouillet-Béranger, P. Perreau, J. Mazurier, T. Benoist, O. Rozeau, T. Poiroux, M. Vinet, L. Grenouillet, J-P. Noel, N. Posseme, S. Barnola, F. Martin, C. Lapeyre, M. Cassé, X. Garros, M-A. Jaud, O. Thomas, G. Cibrario, L. Tosti, L. Brévard, C. Tabone, P. Gaud, S. Barraud, T. Ernst and S. Deleonibus (CEA/LETI Minatec)

The authors of this paper say that for 20nm node and below, they have proven that planar undoped channel Fully Depleted SOI devices are easier to integrate than bulk, non planar devices like FinFET. The paper gives an overview of the main advantages provided by this technology, as well as the key challenges that need to be addressed.


#3.3:  Anomalous Electron Mobility in Extremely-Thin SOI (ETSOI) Diffusion Layers with SOI Thickness of Less Than 10 nm and High Doping Concentration of Greater Than 1x1018cm-3

N. Kadotani,T. Takahashi, K. Chen,T. Kodera, S. Oda, K. Uchida*  (Tokyo Institute of Technology, *also with PRESTO)

This paper is the first to report carrier transport in heavily doped ETSOI diffusion layers. The authors found that electron mobility in the heavily doped ETSOI diffusion layer is totally different from electron mobility in heavily doped bulk Si. In other words, electron mobility is enhanced in thinner ETSOI diffusion layers (Tsoi>5nm), whereas electron mobility is degraded as dopant concentration increases when Tsoi is 2nm. The authors conclude that this information will be indispensable for the design of aggressively scaled ETSOI devices as well as 3D FETs.


#3.4:  Work-function Engineering in Gate First Technology for Multi-VT Dual-Gate FDSOI CMOS on UTBOX

O. Weber, F. Andrieu, J. Mazurier, M. Cassé, X. Garros, C. Leroux, F. Martin, P. Perreau, C. Fenouillet-Béranger, S. Barnola, R. Gassilloud, C. Arvet*, O. Thomas, J-P. Noel, O. Rozeau, M-A. Jaud, T. Poiroux, D. Lafond, A. Toffoli, F. Allain, C. Tabone, L. Tosti, L. Brévard, P. Lehnen #, U. Weber#, P.K. Baumann#, O. Boissiere#, W. Schwarzenbach+, K. Bourdelle+, B-Y Nguyen+, F. Boeuf*, T. Skotnicki*, and O. Faynot (CEA-LETI Minatec, *STMicroelectronics, #AIXTRON AG, +SOITEC)

For the first time, the authors demonstrate low-VT (VTlin ~± 0.32) nMOS and pMOS adjusted in a gate first FDSOI technology by work-function engineering of TiN/TaAlN metal gates. Especially, for low-VT pMOS, various Chemical-Vapor-Deposited TaAlN stacks with optimized Al concentration have been studied to finely tune the work-function above midgap while maintaining good reliability and mobility. Short channel performance of 500μA/μm ION and 245μA/μm IEFF at 2nA/μm IOFF and VDD=0.9V is reported on pMOS with a TaAlN gate. In addition, it is found that the combination of these two metal gates with either n- or p-doped ground planes below the Ultra-Thin Buried Oxide (BOX) can offer 4 different VT from 0.32V to 0.6V for both nMOS and pMOS.


#8.1: Compact Modeling and Analysis of Coupling Noise Induced by Through-Silicon Vias in 3-D ICs

C. Xu, R. Suaya*, K. Banerjee (UC Santa Barbara, *Mentor Graphics)

This work presents compact models for cases without and with the high conductivity buried layer in dual-well bulk CMOS, which can be employed for keep away radius estimation. A comparative analysis of the coupling noise due to TSV in both dual-well bulk CMOS and PD-SOI is presented. The noise coupling for PD-SOI is much smaller than that of bulk CMOS due to the significantly shorter TSV height compared to that in bulk CMOS.


#8.2:  Large Signal Substrate Modeling in RF SOI Technologies

S. Parthasarathy, B. Swaminathan, A. Sundaram, R.A. Groves, R.L. Wolf, F.G. Anderson (IBM SRDC)

This paper describes a large signal high resistivity (HR) SOI substrate modeling methodology for high power circuit applications such as RF switches.  The authors show that using a varactor to model the BOX capacitor improves the harmonic distortion predictions from simulations for circuits in RF/Analog applications.


#8.5: MuGFET Carrier Mobility and Velocity: Impacts of Fin Aspect Ratio, Orientation and Stress

N. Xu, X. Sun, W. Xiong*, C. R. Cleavelin, T.-J. King Liu (UC Berkeley, *Texas Instruments)

The authors made a detailed study of the impacts of fin aspect ratio and crystalline orientation and process-induced channel stress on the performance of multi-gate transistors. The MuGFETs studied in this work were fabricated on (100) SOI substrates, with either <100> or <110> fin orientation.  They found that CESL-induced stress provides for the greatest enhancement in carrier mobility and ballistic velocity, for n- and p-channel FinFETs and Tri-Gate FET structures. Extracted carrier velocity values in short-channel FinFETs still largely depend on carrier mobility.


#11.1:  Dual Strained Channel Co-Integration into CMOS, RO and SRAM Cells on FDSOI Down to 17nm Gate Length

L. Hutin, C. Le Royer, F. Andrieu, O. Weber, M. Cassé, J.-M. Hartmann, D. Cooper, A. Béché*, L. Brevard, L. Brunet, J. Cluzel, P. Batude, M. Vinet, O. Faynot (CEA LETI Minatec, CEA-INAC)

The authors presented the first successful Dual Strained Channel On Insulator (DSCOI) planar co-integration of tensily strained SOI nFETs and compressively strained SiGeOI pFETs down to 17nm gate length with functional ring oscillators and 6T SRAM cells.  Strained SiGe channels were found to present up to 92% long channel mobility improvement (Eeff=0.6MV/cm); the asset of effective mass reduction is highlighted for short channel pFETs. Moreover, the co-integration with sSOI nFETs leads to well-adjusted Vth,n and Vth,p with a single mid-gap gate for high performance applications, as shown by a 39% improvement of the ring oscillators propagation delay compared to the SOI reference.


#11.2: A Solution for an Ideal Planar Multi-Gates Process for Ultimate CMOS?

S. Monfray, J.-L. Huguenin, M. Martin*, M.-P. Samson, C. Borowiak, C. Arvet, JF. Dalemcourt*, P. Perreau*, S. Barnola*, G. Bidal, S. Denorme, Y. Campidelli, K. Benotmane*, F. Leverd, P. Gouraud, B. Le-Gratiet, C. De-Butet*, L. Pinzelli, R. Beneyton, T. Morel, R.Wacquez*, J. Bustos, B. Icard*, L. Pain*, S. Barraud*, T. Ernst*, F. Boeuf, O. Faynot*, T. Skotnicki (STMicroelectronics, *CEA LETI Minatec)

The authors demonstrate for the first time high-performant planar multi-gates devices integrated on an SOI substrate, with Si-conduction channel of 4nm, allowing drive current up to 1350μA/μm @Ioff=0.4nA/μm. They also demonstrate an ideal planar self-aligned solution, based on the direct exposure of a HSQ layer through a 5nm Si-channel. This opens the way to an easy planar multi-gate process for ultimate CMOS (11nm node & below), fully co-integrable with conventional devices.


#12.1: 32nm High-density High-speed T-RAM Embedded Memory Technology

R. Gupta, F. Nemati, S. Robins, K. Yang, V. Gopalakrishnan, J.J. Sundarraj, R. Chopra, R. Roy, H.-J. Cho*, W.P. Maszara*, N.R. Mohapatra*, J. Wuu**, D. Weiss**, S. Nakib (T-RAM Semiconductor, *GLOBALFOUNDRIES, **AMD)

The authors present Thyristor Random Access Memory (T-RAM) as an ideal candidate for embedded memory due to its substantially better density-performance and logic process compatibility.  T-RAM technology with substantially better density-performance tradeoff  was previously reported was previously reported at the 130nm technology node. This paper is the first to report implementation details in a 32nm HKMG SOI CMOS logic process, with read and write times of 1ns and bit fail rate under 0.5ppm.


#12.3:  A Novel Low-Voltage Biasing Scheme for Double Gate FBC Achieving 5s Retention and 1016 Endurance at 85ºC

Z. Lu, N. Collaert, M. Aoulaiche, B. De Wachter, A. De Keersgieter, W. Schwarzenbach*, O. Bonnin*, K. K. Bourdelle*, B.-Y. Nguyen**, C. Mazure*, L. Altimime, M. Jurczak (IMEC, *SOITEC, **SOITEC-USA)

A novel low-voltage biasing scheme on ultra-thin BOX FDSOI floating body cell is experimentally demonstrated. The new biasing scheme enhances the positive feedback loop. Therefore, the required VDS can be reduced to 1.5V while 5 seconds retention time can still be achieved at 85oC. Endurance up to 1016 cycles is shown.


#16.6: Realizing Super-Steep Subthreshold Slope with Conventional FDSOI CMOS at Low-Bias Voltages (Late News)

Z. Lu*#, N. Collaert*, M. Aoulaiche*, B. De Wachter*, A. De Keersgieter*, J. Fossum#, L. Altimime*, M. Jurczak* (*IMEC, #U. Florida/Gainesville)

The authors report the first experimental demonstration of a super-steep subthreshold slope (the smallest ever reported experimentally) with ultra-thin BOX FDSOI standard CMOS transistors. This work addresses the scaling challenge of continuing to reduce power consumption by lowering operation voltage.  Record steep SS of 72μV/dec for Lg=25nm and 58μV/dec for Lg=55nm are achieved with low voltages. The device also exhibits high ION (~100μA/μm), large ION/IOFF ratio of 108 with 0.5V gate swing for Lg=55nm MOSFETs and excellent reliability.


#18.3: Prospects for MEM Logic Switch Technology (Invited), T.-J. King Liu, J. Jeon, R. Nathanael, H. Kam, V. Pott*, E. Alon (UC Berkeley, *Institute of Microelectronics/Singapore)

This paper provides an overview of recent progress in device design, materials/process integration and technology scaling toward achieving micro-electro-mechanical  (MEM) switches suitable for ultra-low-power digital IC applications.


#27.5: A 0.039um2 High Performance eDRAM Cell Based on 32nm High-K/Metal SOI Technology

N. Butt, K. Mcstay, A. Cestero, H. Ho, W. Kong, S. Fang, R. Krishnan, B. Khan, A. Tessier, W. Davies, S. Lee, Y. Zhang, J. Johnson, S. Rombawa, R. Takalkar, A. Blauberg, K.V. Hawkins, J. Liu, S. Rosenblatt, P. Goyal, S. Gupta, J. Ervin, Z. Li, S. Galis, J. Barth, M. Yin, T. Weaver, J. H. Li, S. Narasimha, P. Parries, W.K. Henson, N. Robson, T. Kirahata, M. Chudzik, E. Maciejewski, P. Agnello, S. Stiffler, and S.S. Iyer (IBM SRDC)

The authors present the industry’s smallest eDRAM cell and the densest embedded memory integrated into the highest performance 32nm High-K Metal Gate SOI based logic technology. With aggressive cell scaling, High-K/Metal trench lowers parasitic resistance while maximizing capacitance. Fully-integrated 32Mb product prototypes demonstrate state-of-the-art sub 1.5ns latency with excellent retention and yield characteristics. The sub 1.5ns latency and 2ns cycle time have been verified with preliminary testing whereas even better performance is expected with further characterization. In addition, the trench capacitors set the industry benchmark for the most efficient decoupling in any 32nm technology.


#34.2:  Strained SiGe and Si FinFETs for High Performance Logic with SiGe/Si Stack on SOI

I. Ok, K. Akarvardar*, S. Lin**, M. Baykan^, C.D. Young, P.Y. Hung, M.P. Rodgers^^, S. Bennett^^, H.O. Stamper^^, D.L. Franca^^, J. Yum#, J.P. Nadeau##, C. Hobbs, P. Kirsch, P. Majhi, R. Jammy (SEMATECH, *GLOBALFOUNDRIES, **UMC, ^U.Florida, ^^CNSE, #U. Texas/ Austin, ##FEI)

The authors have demonstrated high performance p-channel Si/SiGe stacked FinFETs with salient features including 1) high intrinsic mobility; 2) good interface quality without the need for a Si cap between SiGe and High-k; 3) low series resistance; 4) process-induced strain additivity; and 5) a convenient threshold voltage for high performance logic using a midgap metal gate. They also demonstrate a dual channel scheme for high mobility CMOS FinFETs.


#34.3: Understanding of Short-Channel Mobility in Tri-Gate Nanowire MOSFETs and Enhanced Stress Memorization Technique for Performance Improvement

M. Saitoh, Y. Nakabayashi, K. Ota, K. Uchida*, and T. Numata (Toshiba Corp., *Tokyo Institute of Technology)

The authors found that short-channel mobility in SOI nanowire transistors (NW Tr.) is dominated by the strain induced in the NW channel. They enhanced NW strain by the stress memorization technique (SMT). In <110> NW nFETs, Ion on the same DIBL largely increases by SMT thanks to mobility increase and parasitic resistance reduction.  They conclude that stress engineering is highly effective for the performance improvement of scaled NW Tr.


#34.5:  Investigation of Hole Mobility in Gate-All-Around Si Nanowire p-MOSFETs with High-k/Metal-Gate: Effects of Hydrogen Thermal Annealing and Nanowire Shape

P. Hashemi, J.T. Teherani, J.L. Hoyt (MIT Microsystems Technology Laboratories)

The authors present a detailed study of hole mobility for gate-all-around Si NW p-MOSFETs with conformal high-k/MG and various hydrogen annealing processes. The devices are fabricated along the <110> direction on (100) thin body SOI.  Increasing hole mobility is observed with decreasing NW width down to 12 nm. A 33% hole mobility enhancement is achieved relative to universal (100) at high Ninv.


#35.4:  A Quantitative Inquisition into ESD Sensitivity to Strain in Nanoscale CMOS Protection Devices

D.Sarkar, S. Thijs*, D. Linten*, C. Russ**, H. Gossner**, K. Banerjee, (UC Santa Barbara, *IMEC, **Infineon Technologies)

The authors investigated the impact of strain on different ESD protection devices. It is shown for the first time that the ESD sensitivity to strain can vary substantially depending on whether the devices stressed are bulk or SOI and on the mode in which they are stressed.  investigated. SOI NMOS exhibits about 20% improvement in ESD robustness in GG mode. The authors conclude that strain will play an important role in optimization of ESD device robustness of advanced CMOS technologies.