Physical Measurement Laboratory Semiconductor and Dimensional Metrology Division

1

Physical Measurement Laboratory Semiconductor and Dimensional Metrology DivisionNanoscale Metrology GroupMEMS Measurement Science and Standards Project

MEMS 5-in-1 RM Slide Set #1

Reference Materials 8096 and 8097The MEMS 5-in-1 Test Chips

– Overview of the MEMS 5-in-1 RMs

Photo taken by Curt Suplee, NIST

2

List of MEMS 5-in-1 RM Slide SetsSlide Set # Title of Slide Set

1 OVERVIEW OF THE MEMS 5-IN-1 RMs2 PRELIMINARY DETAILS

THE MEASUREMENTS:3 Young’s modulus measurements4 Residual strain measurements

5 Strain gradient measurements6 Step height measurements7 In-plane length measurements

8 Residual stress and stress gradient calculations

9 Thickness measurements (for RM 8096)

10 Thickness measurements (for RM 8097)

11 REMAINING DETAILS

3

Outline for theOverview of the MEMS 5-in-1 RMs

1 Background

2 The MEMS 5-in-1 RM a. What is it? b. The 5 Standard Test Methods c. Uses of the MEMS 5-in-1 RM

3 Some Specifics a. The 2 Types of Chips b. The Packaging c. The Chip Designs d. 8 Properties Reported e. Example NIST Reference Values

4 Material Available

5 Instrumentation

6 Summary7 References

4

Why is MEMS Important?• A $10.2B industry (in 2011)

– Yole forecasts $21.1B industry (in 2017) – doubled from 2011– Growth rate (13 %/year) is healthy

• MEMS being pulled into the market (esp. via the consumer market)• Spread out over many (say 100) smaller companies

– MEMS acquisitions have soared in 2011 (>300 % increase)

• MEMS is an enabling technology– Improved medical device performance

• In-vitro diagnostics• Micro dispensers for drug delivery• Accelerometers in pacemakers• Wireless implants

– Puts the “Smart” in Smart Phones• Accelerometers, gyros, pressure sensors, microphones,…• The future will see combination sensors

– Etc.

• As the field continues to grow, NIST can facilitate the introduction of product data sheets to allow inter-comparisons of consumer products.

“MEMS Technology has the potential to change our daily lives as much as the

computer has.”

(Are we there yet?)

5

5

MEMS = microelectromechanical systems

5-in-1 = test structures for five standard test methods on one physical test chip

1. Young’s modulus (SEMI MS4)2. Residual strain (ASTM E 2245)3. Strain gradient (ASTM E 2246)4. Step height (SEMI MS2)5. In-plane length (ASTM E 2244)

RM = Reference Material: a material or substance one or more of whose property values are sufficiently homogeneous, stable, and well established to be used for the calibration of an apparatus, the assessment of a measurement method, or for assigning values to materials.

6

The MEMS 5-in-1 RM(What is it ?)

7

The 5 Standard Test Methods

Calculations performed on the MEMS Calculator website (Standard Reference Database 166)

These standards include precision and bias data (so considered validated standards)

ASTM E 2245 residual strain

ASTM E 2244in-plane length

ASTM E 2246strain gradient

1

2

3

L

SEMI MS2step height

SEMI MS4Young’s modulus

4

5

Intended for•MEMS designers•Test equipment manufacturers

– Who may want to buy in bulk to sell with their instruments

•IC and MEMS foundries and services

Uses of the MEMS 5-in-1• To validate use of the documentary standards

(so companies can compare their in-house measurements taken on the RM with NIST measurements)• To characterize or validate a process• To take local measurements • To compare measurements meaningfully (e.g., between suppliers and customers)• To trouble-shoot a process (to improve yield and track failure sources to speed development)• To calibrate an instrument

8

Photo taken by Curt Suplee, NIST

9

The 2 Types of Chips• RM 8097

– Fabricated using a polysilicon multi-user surface-micromachining MEMS process with a backside etch

– Material properties of the first or second polysilicon layer are reported

– Chip dimensions: 1 cm x 1 cm

• RM 8096– Fabricated on a multi-user

1.5 µm CMOS process followed by a bulk-micromachining etch

– Material properties of the composite oxide layer are reported

– Chip dimensions: 4600 µm x 4700 µm

10

NIST-on-a-Chip-type-of Packagingtesting solution provided

all measurements can be performed in this package

lidchip

PZT

Photo taken by Erik Secula, NIST

11

The Chip DesignsEach RM has 6 sections1.Young’s modulus (uses SEMI standard MS4)2.Residual strain (uses ASTM standard E 2245)3.Strain gradient (uses ASTM standard E 2246)4.Step height (uses SEMI standard MS2)5.In-plane length (uses ASTM standard E 2244)6.Certification Plus

RM 8097RM 8096

12

8 Properties Reported[using 5 Test Methods (TMs)]

1. Young’s modulus (uses SEMI standard MS4)2. Residual strain (uses ASTM standard E 2245)3. Strain gradient (uses ASTM standard E 2246)4. Step height (uses SEMI standard MS2)5. In-plane length (uses ASTM standard E 2244)6. Residual stress (calculations in Young’s modulus TM SEMI MS4)7. Stress gradient (calculations in Young’s modulus TM SEMI MS4)8. Beam thickness

a. For RM 8096 [uses step height TM (SEMI MS2) with electro-physical technique]b. For RM 8097 [uses step height TM (SEMI MS2) with opto-mechanical technique]

12

MeasurementNIST Reference Value

± Expanded Uncertainty(for k=2 for ≈95 % confidence)

1. Effective Young’s modulus, E 56.6 GPa ± 17.8 GPa

2. Effective residual strain, r –2.83×10–3 ± 0.71×10–3

3. Effective strain gradient, sg 1101 m–1 ± 167 m–1

4. Step height, step1AB 0.499 µm ± 0.108 µm

5. In-plane length, L (at 25×) 202.2 µm ± 3.0 µm

6. Effective residual stress, r –160 MPa ± 67 MPa

7. Effective stress gradient, g 62.3 TPa/m ± 18.9 TPa/m

8. Thickness, toxide 2.65 µm ± 0.20 µm

Example NIST Reference Values for RM 8096

NOTE: Effective values are reported if there are non-idealities associated with the geometry and/or composition of the test structures.

13

14

Material Available • NIST SP 260-177: A User’s Guide (2013 Edition)• The 5 standard test methods• Data analysis sheets

– On the MEMS Calculator website (Standard Reference Database 166)– Accessible via the NIST Data Gateway (http://srdata.nist.gov/gateway/)

with the keyword “MEMS Calculator”– Performs the calculations and verifies the data

• Report of Investigation (ROI)– Includes NIST Reference Values:

• A best estimate of the true value provided on a NIST Certificate/Certificate of Analysis/Report of Investigation where all known or suspected sources of bias have not been fully investigated by NIST

Instrumentation1. Optical interferometric microscope (or comparable instrument)

– In-plane length– Residual strain– Strain gradient– Step height – Thickness

• RM 8096: When applicable platforms are reflective• RM 8097: For measurement of B and/or C (and perhaps A)

2. Optical vibrometer (or comparable instrument)– Young’s modulus

3. Stylus profilometer (or comparable instrument)– Thickness

• RM 8096: When applicable platforms are not reflective• RM 8097: For measurement of A (for a lower uncertainty value), if used

C

15

16

16

17

References• Overview articles1. J. Cassard, J. Geist, and J. Kramar, “Reference Materials 8096 and 8096 – The Microelectromechanical Systems 5-in-1 Reference

Materials: Homogeneous and Stable,” More-Than-Moore Issue of ECS Transactions, Vol. 61, May 2014.2. J. Cassard, J. Geist, C. McGray, R. A. Allen, M. Afridi, B. Nablo, M. Gaitan, and D. G. Seiler, “The MEMS 5-in-1 Test Chips

(Reference Materials 8096 and 8097),” Frontiers of Characterization and Metrology for Nanoelectronics: 2013, NIST, Gaithersburg, MD, March 25-28, 2013, pp. 179-182.

3. J. Cassard, J. Geist, M. Gaitan, and D. G. Seiler, “The MEMS 5-in-1 Reference Materials (RM 8096 and 8097),” Proceedings of the 2012 International Conference on Microelectronic Test Structures, ICMTS 2012, San Diego, CA, pp. 211-216, March 21, 2012.

• User’s guide4. J.M. Cassard, J. Geist, T.V. Vorburger, D.T. Read, M. Gaitan, and D.G. Seiler, “Standards Reference Materials: User’s Guide for

RM 8096 and 8097: The MEMS 5-in-1, 2013 Edition,” NIST SP 260-177, February 2013 (http://dx.doi.org/10.6028/NIST.SP.260-177).

• Standards5. SEMI MS4-0212, “Test Method for Young’s Modulus Measurements of Thin, Reflecting Films Based on the Frequency of Beams in

Resonance,” February 2012. (Visit http://www.semi.org for ordering information.)6. SEMI MS2-0212, “Test Method for Step Height Measurements of Thin Films,” February 2012. (Visit http://www.semi.org for ordering

information.)7. ASTM E 2245-11, “Standard Test Method for Residual Strain Measurements of Thin, Reflecting Films Using an Optical

Interferometer,” December 2011. (Visit http://www.astm.org for ordering information.)8. ASTM E 2246-11, “Standard Test Method for Strain Gradient Measurements of Thin, Reflecting Films Using an Optical

Interferometer,” January 2012. (Visit http://www.astm.org for ordering information.)9. ASTM E 2244-11, “Standard Test Method for In-Plane Length Measurements of Thin, Reflecting Films Using an Optical

Interferometer,” December 2011. (Visit http://www.astm.org for ordering information.)

• Thickness articles10. J.C. Marshall and P.T. Vernier, “Electro-physical technique for post-fabrication measurements of CMOS process layer

thicknesses,” NIST J. Res., Vol. 112, No. 5, pp. 223-256, 2007.11. J.C. Marshall, “New Optomechanical Technique for Measuring Layer Thickness in MEMS Processes,” J. of Microelectromechanical

Systems, Vol. 10, No. 1, pp. 153-157, March 2001.

• Fabrication12. The RM 8096 chips were fabricated through MOSIS on the 1.5 µm On Semiconductor (formerly AMIS) CMOS process. The URL

for the MOSIS website is http://www.mosis.com. The bulk-micromachining was performed at NIST.13. The RM 8097 chips were fabricated at MEMSCAP using MUMPs-Plus! (PolyMUMPs with a backside etch). The URL for the

MEMSCAP website is http://www.memscap.com.

• SEMI’s MEMS/NEMS Committee– MEMS Materials Characterization TF

• ASTM’s E08 Committee on Fatigue and Fracture– E08.05 Subcommittee on Cyclic Deformation and Fatigue Crack

Formation• E08.05.03 Task Group on Structural Films for MEMS

• For industry cost-share and engineering support– MOSIS (for RM 8096)– MEMSCAP (for RM 8097)

• NIST– Statistical Engineering Division, Measurement Services Division, Center

for Nanoscale Science and Technology, Public and Business Affairs Office– Quality– Experts– MEMS Measurement Science and Standards Project

• Test Structures Subgroup18

AcknowledgmentMark Crockett (MEMSMART)Win Baylies (BayTech Group)

Jon Geist (leader), Richard Allen

P. Thomas Vernier

Busbee Hardy

Sreeramesh Kalluri (Ohio Aerospace Institute)

Stefan Leigh Robert Watters

Ted Doiron

Theodore Vorburger and David Read

Craig McGray (Modern Microsystems)Yaqub Afridi (Potomac Networks)Brian Nablo