Metrology Tools for Flexible Electronics and Display Substrates. Min Yang

Transcription

1 Metrology Tools for Flexible Electronics and Display Substrates Min Yang 1

2 Acknowledgement The speaker would like to sincerely thank the following collaborators for their contributions: Roger Posusta, Bruker Corporation, for white light interferometry optical profiler and stylus profiler analyses Karl Rakos, DuPont Teijin Polyester Films UK Ltd, for providing the data for defect classification analysis. Suresh Kuiry, Bruker Corporation, for scratch test and analysis. 2

3 Outline This talk will show examples that use metrology tools to characterize the critical dimensions, surface morphologies and defects on flexible electronic circuits and display substrates. Trace evaluations with White light interferometry (WLI) WLI optical profiler vs. stylus profiler for trace analysis Defect detection and classification with WLI Scratch simulation with tribometer for display panel 3

4 WLI Optical Profiler Interference fridges are similar to contour map lines 100 Each line in contour map represents a fixed elevation 300nm Each line in interometry represents a fixed height Non-contact, non-destructive Fast, accurate, and repeatable Sub-nanometer vertical resolution Image large areas at once 4

5 WLI Illustration Focus plane The optical system scans vertically and records the positions that are in focus at each height. 5

6 WLI Trace Analysis - Ink Supplier Selection Supplier A 30um Traces, 40um Spaces Supplier B 30um Traces, 40um Spaces Supplier C 30um Traces, 40um Spaces 100um Traces, 50um Spaces 100um Traces, 75um Spaces 100um Traces, 50um Spaces 6/21/2017 Bruker Confidential 6 6

7 Supplier A 100um Traces, 50um Spaces WLI Trace Analysis Automated Trace Analysis 6/21/2017 Bruker Confidential 7 7

8 WLI Trace Analysis Automated Multi-Region Analysis 6/21/2017 Bruker Confidential 8 8

9 Stylus Profilers Measures surface profile by moving stylus across sample. Copyright Bruker Corporation. All rights reserved 9 9

10 Stylus Profiler Capabilities Large Part Ranges Wafers >200 mm Low stylus force Down to 0.03mg Vertical resolution 0.01nm resolution Step height repeatability 5 Å 10 10

11 WLI Optical Profiler vs. Stylus Profiler Trace analysis for thicker traces (>100nm) WLI Optical Profiler Stylus Profiler Good correlation between stylus and optical profilers 6/21/

12 WLI Optical Profiler Analysis Trace analysis for thin traces (<100nm) When the silver trace thickness is <100nm, it becomes transparent and difficult for the optical profiler to measure the complete trace 6/21/2017 Bruker Confidential 12

13 Stylus Profiler Analysis Trace analysis for thin traces (<100nm) Stylus profiler has a 0.01nm resolution without opaque sample requirements 6/21/2017 Bruker Confidential 13

14 Stylus Profiler Analysis Thin ring pad (~100nm) 6/21/2017 Bruker Confidential 14

15 WLI Defect Analysis Defect Detection & Identification Defect Type T1 T2 T3 T4 T5 T6 Parameters Islands * * Spd * Sv * Diameter * X Y Sag * % Valid Pixel * Able to identify 1 or 2 critical parameters with Pass/Fail criteria for each type of defects 6/21/

16 T1- Extra Materials T1_1 T1_2 T1_3 T1_4 Number of features detected Peak Density Counting the number of Islands and monitoring Spd can identify T1 type of defects 6/21/

17 T2- Extra Materials T2_1 T2_2 T2_3 T2_4 (Outlier) Number of features detected Counting the number of Island with a threshold (~20) can classify T2 type of defects 6/21/

18 T3- Holes (Deep) T3_1 T3_2 Maximum valley depth Sv can detect deep holes 6/21/

19 T3_3 T3- Holes (Shallow) T3_4 T3_5 T3_6 Maximum valley depth Sv can even detect shallow holes 6/21/

20 T4_1 T4- Extra Materials T4_2 Diameter can detect T4 type of defects 6/21/

21 T5- Peaks (1 of 3) T5_1 T5_2 T5_3 T5_4 Curvature Curvature Max Sag can easily detects peaks 6/21/

22 T5- Sharp Peaks (2 of 3) T5_s1 T5_s2 T5_s3 Curvature Curvature Max Sag can easily detects sharp peaks 6/21/

23 T5- Sharp peaks (3 of 3) T5_s4 T5_s5 T5_s6 Curvature Curvature Max Sag can easily detects sharp peaks 6/21/

24 T6- Missing Materials T6_1 T6_2 T6_3 T6_4 Valid Pixels can easily detect T6 type of defects by detecting the missing pixels 6/21/

25 Scratch Simulation Test for Display Panel Material Optimization Scratch test was performed on Light Guide Plate (LGP) against diffuser film with different combinations of resin and beads 25

26 Test Set-up Bruker UMT TriboLab Test was performed on a UMT-TriboLab using a linear drive and a force sensor. The LGP specimen was installed using four screws on the sample stage. A self-aligned flat holder was used to mount the diffuser with 1 square inch area, using double sided adhesive tape. 26

27 Friction of Urethane Beads with Different Resin UV resin Heat set resin Pressure : 100 g.cm-2 50 g.cm-2 10 g.cm-2 The scratch tests were performed with a constant load (Fz) over 2 distance at a velocity of 5 mm/s. LGP surface was visually examined and found scratches on most cases after the test. UV resin + urethane beads are a better combination of materials for this application. 27

28 Friction of UV Resin with Different Beads Urethane beads Nylon beads The scratch tests were performed with a constant load (Fz) over 2 distance at a velocity of 5 mm/s. LGP surface was visually examined and found scratches on most cases after the test. More tests are needed to optimize the bead material. 28

29 Summary WLI optical profiler is a very useful tool to characterize the critical dimensions and surface morphologies, detect and classify defects on flexible electronic circuits and display substrates. Stylus profiler is a good complimentary tool to check for potential artifacts of optical measurements for samples that are very thin or with different materials. Scratch simulation test with a tribometer could be useful for material selections in flexible display panels. 29

30 Contact Information Karl Rakos DuPont Teijin Polyester Films UK Ltd