The Business Case for MEMS Standardization Semicon West MIG/SEMI Workshop

Transcription

1 The Business Case for MEMS Standardization Semicon West MIG/SEMI Workshop Alissa M. Fitzgerald, Ph.D. 15 July th anniversary

2 Overview About AMFitzgerald Lessons from History Silicon on Insulator (SOI) Wafers Deep Reactive Ion Etch (DRIE) Call to Action Page 2

3 AMFitzgerald services MEMS Innovation MEMS Solutions Technology Strategy Creation of novel designs and IP Paths to manufacturing and market Key insights from MEMS experts Page 3

4 Full development services from concept to production AMFitzgerald in house Strategic partners Advantages of working with us: Multi-disciplinary, expert engineering team focused on MEMS development for volume production Rapid prototyping on state-of-the-art tools common to foundries Own all the design and process IP Bring a mature, de-risked design to the foundry to get better pricing and faster time to production Page 4

5 Lessons from History Standards in Mechanical Engineering

6 History: Spare nuts and bolts available anywhere : Standardization of screw threads was motivated by the railroads Previously, screw threads were proprietary to each machine shop Page 6

7 History: Public safety Exploded locomotive boiler, 1869 Grover Shoe Factory boiler explosion, 1905 In 1911, ASME started to develop codes for safe design of steam boilers and pressure vessels Explosions from poor designs and poor maintenance These standards are still in use today, and evolving Page 7

8 History: Global interchangeability Unified Thread Standard created after WWII to address interchangeability of fasteners between Allies Page 8

9 Typical design process for an Aerospace Engineer Select metal alloy: MIL-STD-5 Known material properties Select metal shapes Sheet metal, extrusions Known shapes and tolerances Select fasteners: NAS, ISO Defined form and function Interchangeability Follow design guidelines Analysis and Design of Flight Vehicle Structures, E.F. Bruhn Roark s Formulas for Stress and Strain Create drawing using ASME/ANSI Y14.5 standard Precisely communicate design to machine shop Rocket Nozzle Fairing BS/MS engr. with 3 yrs. experience Page 9

10 Typical design process for a MEMS Engineer Select material types Properties not standardized; uncertainty in models Specify wafers Engineer orders customized wafers, wait 8 weeks Design anchors, combs, cantilevers, etc. Twiddle FEA model due to uncertainty in boundary conditions, DRIE tolerances Reinvent structures well-known to others, but never made public Send GDS file and desired process flow to foundry Need to discuss design with foundry engineers on phone Electrostatic Optical Switch MS/PhD engr. with 10 yrs. experience Page 10

11 Why pursue standards for MEMS? Features of standards Pro Con Interchangeability Public safety Decreases expertise needed to solve problem Time to market Clear communication of essential information Market efficiency improved Easy and inexpensive to change out components Increase confidence in MEMS for life-safety applications Lower-skilled employees may be used Reduce time wasted on reinvention, capture revenue faster Reduce errors between parties who speak different languages or have different expertise levels More vendors available, better prices for buyers Reduces competitive barriers for component suppliers None Naïve reliance on standards may cause unintended consequences None Oversimplification, or important, subtle details left out Specialty suppliers will have more competition and may lose market share Page 11

12 Case Studies

13 Case studies: SOI wafers and DRIE Of interest to both MEMS and semiconductor industries Mechanical analogues How we do it today How much better it could be in the future Savings Page 13

14 Mechanical Analogue: Screw Threads ISO 724:1993 ISO Metric profile External (bolt thread) Internal (nut thread) Basic mm Size mm Thread Designation Simple Thread Designation Pitch mm Class Major Dia d=d max. min. Pitch Dia d2=d2 max. min. Minor Dia d3 max. min. Clas s Minor Dia D1 min. max. Pitch Dia d2=d2 min. max. Major Dia d=d min. max. Tap Drill 0.25 M0.25x0.075 M0.25x g H M0.3x0.08 M0.3x g H M0.3x0.09 M0.3x g H M0.35x0.09 M0.35x g H M0.4x0.1 M0.4x g H M0.45x0.1 M0.45x g H Page 14

15 SOI wafer: specifications Device layer thickness Device layer thickness tolerance Device layer growth method: CZ or FZ Buried oxide layer thickness Handle thickness Handle thickness tolerance Handle growth method: CZ or FZ Device layer Buried oxide layer Handle wafer Device layer dopant Device elec. resistivity Device layer crystal orientation Handle dopant Handle elec. resistivity Handle crystal orientation Set of mechanical and electrical specifications define the wafer Commonly used combinations exist Page 15

16 SOI wafer purchase process - now Page 16 Costs to Buyer Engineer must specify wafer exactly from many spec permutations Potential for errors Order details handled by engineer, not buyer Higher labor costs Wait time for quote, lead time for wafers to arrive Time wasted Minimum order quantities, difficulty using leftover wafers Money wasted Costs to Seller Must speak buyer s language to receive and process quote request Potential for errors Need engineer s input to determine price for custom wafers Higher labor costs All wafers built to order Complex tracking system needed, delay of revenue Excess material in inventory to anticipate wide range of customer needs Company s cash tied up

17 What if we had? Standardized combinations of SOI wafers specifications, just like for screw threads Low hanging fruit for a standardization committee! Just agree on a naming convention and create tables of specification combinations Page 17

18 SOI wafer purchase with standards Savings to Buyer Engineer picks from list of standard wafers + Time: days Order handled entirely by a buyer, not engineer + $0.1K Quick quote for standard wafer, minimized lead time + Time: weeks Lower MOQ, extra wafers interchangeable with other projects + $1K Savings to Seller No need for staff to speak foreign language(s) + $0.1K No need to consult with production engineers + $0.1K Wafers ship immediately, realize revenue weeks earlier + Net Present Value ~$0.1K Minimize inventory with more consistent orders + Liberated cash ~$100K Page 18 Net savings per order: Weeks, $1Ks Net savings per order: $0.1Ks Liberated cash: $100Ks

19 Mechanical Analogue: Cutting speed/feed rate table Machine settings for optimum cutting as a function of: Metal type Tool type, diameter Cutting RPM, depth Minimizes tool wear, chatter/vibration, part damage Page 19

20 Deep Reactive Ion Etch (DRIE) Multiple recipe settings for optimum etch performance: Gas flows, duration Platen power, cooling rate, etc. Design practices to minimize etch lag Page 20

21 DRIE processing - now Costs to Designer Exact tolerances of foundry s DRIE recipe unknown (mask vs. actual) Impossible to hit MEMS performance specs on first run Models must be hand-tuned based on foundry results Across-wafer etch uniformity unknown Impossible to predict yield Over-ordering of wafers Costs to Foundry Foundry must develop new recipes for each customer s etch pattern Time and money for development Utilization of process engineers Suboptimal etch recipes Lower wafer throughput, excess gas consumption Lost tool capacity Page 21

22 What if we had? Standard test patterns to calibrate tool and recipe performance Etch recipe parameter guidelines based on: Material to be etched Mask preparation Etch linewidth and aspect ratio Silicon loading Sidewall smoothness Cooling rate This will take serious work but look at payoff Page 22

23 DRIE processing with standards Savings to Designer Accurate models, reach production faster + Time: months + $100Ks Savings to Foundry Shorter DRIE recipe development time + Time: weeks + $10Ks Accurate yield models, minimize inventory + $100Ks Net savings per product: Months, $100Ks Optimized tool throughput and capacity + $100Ks Net savings per product: Weeks, $10Ks Net savings per year: $100Ks Page 23

24 Lack of MEMS standards impairs time to market Digital ASIC Product Development Reference designs, IP blocks Verified physics models Mfg. standards, design rules Process modeling Design simulation Rule checking, Verification New Design 18 months, 95+% yield Product Typical MEMS Fabless Product Development Reference designs, IP blocks Verified physics models Mfg. standards, design rules Process modeling Design simulation Rule checking, Verification New Design 5+ years,?% yield GOOD FAIR POOR Product Page 24

25 We cannot address IoT without standardization! Page 25

26 Call to action: develop the to do list for MEMS standards Form a committee of technical and business stakeholders from a diversity of industry companies MIG can facilitate committee formation Create and organize a master list of potentially useful standards for MEMS devices Identify existing SEMI, NIST, IEEE, JEDEC, SAE, etc. standards and cross-reference Prioritize developing standards that ease common painpoints in industry MIG and SEMI members should join forces where common interests occur: SOI wafers DRIE TSV, 3DIC Wafer bonding Page 26

27 The high-level to do list for MEMS standards Topic Design Methods Manufacturing Communication Standards Material Standards Process Methods Metrology and Inspection Methods Function and Environmental Test Methods Package Methods System Interfaces Potential Collaborators Industry partners GSA (Dr. M. Maher) SEMI SEMI NIST (Dr. M. Gaitan) IEEE, SAE, MIL-SPEC JEDEC JEDEC Page 27

28 Summary Standards development has always been a long, expensive, but fruitful process for many industries MEMS will miss many market opportunities if it cannot reduce time to market and development costs Volunteer for MEMS standards committees! Page 28

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30 Appendix: Existing SEMI Standards Relevant to MEMS (not exhaustive)

31 SEMI standards relevant to MEMS SEMI MS (Reapproved 0812) Guide to Spending Wafer-Wafer Bonding Alignment Targets SEMI MS Test Method for Step-Height Measurements of Thin Films SEMI MS Terminology for MEMS Technology SEMI MS Standard Test Method for Young s Modulus Measurements of Thin, Reflecting Films Based on the Frequency of Beams in Resonance SEMI MS Test Method for Wafer Bond Strength Measurements Using Micro-Chevron Test Structures SEMI M (Reapproved 0512) Guide to Statistical Specifications SEMI MS Guide for Design and Materials for Interfacing Microfluidic Systems SEMI MS Specification for Microfluidic Interfaces to Electronic Device Packages SEMI MS Guide to Evaluating Hermeticity of Mems Packages SEMI MS Specification for High Density Permanent Connections Between Microfluidic Devices SEMI MS Test Method to Measure Fluid Permeation Through MEMS Packaging Materials SEMI M Specification of Silicon-on-Insulator (SOI) for Power Device/ICs Page 31 SEMI M Specification for Silicon-on-Insulator (SOI) Wafers for CMOS LSI