MEMS 5 in1 RM Slide Set 9 Reference

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MEMS 5 -in-1 RM Slide Set #9 Reference Materials 8096 and 8097 The MEMS

MEMS 5 -in-1 RM Slide Set #9 Reference Materials 8096 and 8097 The MEMS 5 -in-1 Test Chips – Thickness Measurements (for RM 8096) Physical Measurement Laboratory Semiconductor and Dimensional Metrology Division Nanoscale Metrology Group MEMS Measurement Science and Standards Project 1 Photo taken by Curt Suplee, NIST

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

List of MEMS 5 -in-1 RM Slide Sets Slide Set # Title of Slide Set 1 OVERVIEW OF THE MEMS 5 -IN-1 RMs 2 PRELIMINARY DETAILS THE MEASUREMENTS: 11 3 Young’s modulus measurements 4 Residual strain measurements 5 Strain gradient measurements 6 Step height measurements 7 In-plane length measurements 8 Residual stress and stress gradient calculations 9 Thickness measurements (for RM 8096) 10 Thickness measurements (for RM 8097) REMAINING DETAILS 2

Outline for Thickness Measurements (for RM 8096) 1 References to consult 2 Thickness for

Outline for Thickness Measurements (for RM 8096) 1 References to consult 2 Thickness for RM 8096 a. Overview b. Equation used c. Data sheet uncertainty equations d. ROI uncertainty equation 3 Location of test structure on RM chip 4 Test structure description 5 Calibration procedure 6 Measurement procedure 7 Using the data sheet 8 Using the MEMS 5 -in-1 to verify measurements 3

1. References to Consult • Overview 1. J. Cassard, J. Geist, and J. Kramar,

1. References to Consult • Overview 1. J. Cassard, J. Geist, and J. Kramar, “Reference Materials 8096 and 8097 – 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. Mc. Gray, 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. 179182. 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 guide (Section 8, pp. 137 -156) 4. J. M. Cassard, J. Geist, T. V. Vorburger, D. T. Read, M. Gaitan, and D. G. Seiler, “Standard 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). • Standard 5. SEMI MS 2 -1113, “Test Method for Step Height Measurements of Thin Films, ” November 2013. (Visit http: //www. semi. org for ordering information. ) • Thickness article 6. 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. • Fabrication 7. The RM 8096 chips were fabricated through MOSIS on the 1. 5 µm On Semiconductor (formerly 4 AMIS) CMOS process. The URL for the MOSIS website is http: //www. mosis. com. The bulkmicromachining was performed at NIST.

2 a. Thickness (for RM 8096) Overview • • • Definition: The height of

2 a. Thickness (for RM 8096) Overview • • • Definition: The height of one or more thin-film layers Purpose: Used in the determination of thin film material parameters, such as Young’s modulus Test structure: Step height test structures Instruments: Interferometric microscope and stylus profilometer or comparable instruments Method: Calculated using the results of six step height measurements taken from four different step height test structures 5

2 b. Thickness Equations (for RM 8096) t 4 = t(gl) t 3 =

2 b. Thickness Equations (for RM 8096) t 4 = t(gl) t 3 = timd(gl/pmd) t 2 = tpmd(imd/fox) toxide = t 1+ t 2+ t 3+ t 4 t 1 = tfox(pmd/sub) where t 4 t 3 t 2 t 1 toxide glass thickness deposited oxide after the m 1 deposition [between the pmd (poly-to-metal dielectric) layer and the glass layer] deposited oxide before the m 1 deposition [between the field oxide and the imd (inter-metal dielectric) layer] field oxide thickness (between the substrate and the pmd layer) 6 composite oxide thickness

2 b. Thickness Equations (for RM 8096) where and where Y=Y 1, Y 2,

2 b. Thickness Equations (for RM 8096) where and where Y=Y 1, Y 2, Y 3, or Y 4 • Consult the thickness article reference for the nomenclature 7

2 c. Data Sheet Uncertainty Equations • Composite oxide thickness combined standard uncertainty, ucoxide,

2 c. Data Sheet Uncertainty Equations • Composite oxide thickness combined standard uncertainty, ucoxide, equation • The data sheet (DS) expanded uncertainty equation is where k=2 is used to approximate a 95 % level of confidence 8

2 d. ROI Uncertainty Equation UROI UDS Ustability expanded uncertainty recorded on the Report

2 d. ROI Uncertainty Equation UROI UDS Ustability expanded uncertainty recorded on the Report of Investigation (ROI) expanded uncertainty as obtained from the data sheet (DS) stability expanded uncertainty 9

3. Location of Structure on RM 8096 (The RM 8096 Chip) • RM 8096

3. Location of Structure on RM 8096 (The RM 8096 Chip) • RM 8096 – Fabricated on a multi-user 1. 5 µm CMOS process followed by a bulkmicromachining etch – Material properties of the composite oxide layer are reported – Chip dimensions: 4600 µm x 4700 µm

3. Location of Structure on RM 8096 For RM 8096 Step For the first

3. Location of Structure on RM 8096 For RM 8096 Step For the first structure: a m 2 over poly 1 step from active area to field oxide Reference platform layer m 2 atop active area Orientation 0º Quantity 4 distinct step height test structures (with 3 occurrences of each structure) to obtain 6 step height measurements for a composite oxide thickness calculation Top view of a step height test structure Locate the step height test structure in 11 this group given the information on the NIST-supplied data sheet

4. Test Structure Description (For RM 8096) z x 12

4. Test Structure Description (For RM 8096) z x 12

5. Calibration Procedure • Calibrate instrument in the z-direction – As specified for step

5. Calibration Procedure • Calibrate instrument in the z-direction – As specified for step height calibrations 13

6. Measurement Procedure • Obtain a step height measurement (according to SEMI MS 2

6. Measurement Procedure • Obtain a step height measurement (according to SEMI MS 2 and using Data Sheet SH. 1. a) for the 6 steps pointed to in the figure below. – – – • Step 1 [i. e. , step 1 AB] Step 2 [i. e. , step 2 r. A] Step 3 [i. e. , step 1 EF] Step 4 [i. e. , step 1 GH] Step 5 [i. e. , step 3 AB(n) ] – use a stylus profilometer (or comparable instrument) due to the top layer being non-reflective Step 6 [i. e. , step 3 BC(0)] – use the NIST-supplied value since this is a measurement taken before the post-processing. Record the step heights and uncertainties in Data Sheet T. 1 14

7. Using the Data Sheet • Find Data Sheet T. 1 – On the

7. Using the Data Sheet • Find Data Sheet T. 1 – 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” Note the symbol next to this data sheet. This symbol denotes items used with the MEMS 5 -in-1 RMs. – • Using Data Sheet T. 1 – – Click “Reset this form” Supply INPUTS to Tables 1 through 3 • – – – Using Data Sheet SH. 1. a results for Table 1 inputs Click “Calculate and Verify” At the bottom of the data sheet, make sure all the pertinent boxes say “ok. ” If a pertinent box says “wait, ” address the issue and “recalculate. ” Compare both the inputs and outputs with the NIST-supplied values 15

8. Using the MEMS 5 -in-1 To Verify RM 8096 Thickness Measurements • If

8. Using the MEMS 5 -in-1 To Verify RM 8096 Thickness Measurements • If your criterion for acceptance is: where Doxide Uoxide(customer) Uoxide positive difference between the thickness value of the customer, toxide(customer), and that appearing on the ROI, toxide thickness expanded uncertainty of the customer thickness expanded uncertainty on the ROI, UROI • Then can assume measuring the composite oxide beam thickness according to SEMI MS 2 according to your criterion for acceptance if: – Criteria above satisfied and 16 – No pertinent “wait” statements at the bottom of your Data Sheet T. 1