Application of Surface Analysis for Root Cause Failure Analysis

Application of Surface Analysis for Root Cause Failure Analysis David A. Cole Evans Analytical Group East Windsor, NJ Specialists in Materials Characterization

Outline Introduction X-Ray Photoelectron Spectroscopy/ Electron Spectroscopy for Chemical Analysis (XPS/ESCA) Additive Migration Adhesion Failure Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) Backside Transfer Ghost Image Summary AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 2

Introduction Techniques provide both organic and inorganic information to varying extents. Techniques are unique in providing direct chemical bonding information. With hundreds of thousands of organic compounds, this information can be very important for problem solving or evaluation. One thing to remember about any organic analysis method: these techniques only evaluate the existing chemistry of the sample. AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 3

XPS Technique Measure kinetic energy (KE) of photoelectrons ejected from sample Calculate photoelectron binding energy (BE) in electron volts, ev BE = hν KE φ + δ hν = excitation x-ray energy (fixed energy) φ = electron spectrometer work function δ = net surface charge Survey spectrum: identifies elements at surface High resolution spectrum: identifies chemical state from peak position and peak shape AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 5

X-Ray Photoelectron Spectrometer X-ray Source Quartz Crystal Monochromator Hemispherical Energy Analyzer Electron Analyzer X-rays Electron Detector Al Anode Sample Electron Source Ultra-High Vacuum Chamber AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 6

XPS Additive Migration Background: Sporadic adhesion failure was observed with a polypropylene film. Film contained erucamide C 22 H 43 NO C = 91.7atom%, N = O = 4.2 atom% NH 2 Questions: What is the surface concentration of erucamide as a function of storage conditions? AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 7

XPS Additive Migration Conclusions: Surface erucamide concentrations are higher than the bulk film as produced. At room temperature migration is slow increasing 60% after 23 days. Migration is rapid at 120 F Increasing 450% in 1.5 days Erucamide layer is ~ 2 nm thick! AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 11

XPS Adhesion Failure Background: Metalized PVC film passed 610 tape pull test But fully processed label appeared to fail between PVC film and Al layer Clear PVC Top Coat Ink Aluminum Clear PVC Film Questions: What is the locus of failure? What is the cause of failure? Adhesive Release Liner AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 12

XPS Adhesion Failure Concentration (Atom%) Sample C Cl O Al Sn N Na Bad - PVC Film 68.5 28.9 2.5 - <0.1 - <0.1 Bad - Top Coat 26.0 3.5 38.4 31.4 0.1 0.2 0.3 Good - PVC Film 71.8 25.5 2.7 - <0.1 <0.1 - Good - Top Coat 55.3 10.0 22.7 11.3 <0.1 0.7 - PVC - theory 66.7 33.3 - - - - - Bad sample: Adhesive failure at PVC - Al interface Good sample: Cohesive failure at PVC - Al interphase AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 14

XPS Adhesion Failure Carbon 1s spectra Sample C Cl O Sample C Cl O Al PVC Film Bad 68.5 28.9 2.5 Good 71.8 25.5 2.7 Top Coat Bad 26.0 3.5 38.4 31.4 Good 55.3 10.0 22.7 11.3 Bad Good Bad Good Normalized Intensity O-C=O C-Cl C-C Normalized Intensity O-C=O C=O C-Cl C-C C-O C-C 294 292 290 288 286 284 282 280 Binding Energy (ev) C-C & C-Cl bonds due to PVC 294 292 290 288 286 284 282 280 Binding Energy (ev) C-C, C-O, & O-C=O bonds due to plasticizer C-O & C=O bonds due to plasma treatment AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 15

XPS Adhesion Failure Conclusions: Good sample has mixed mode failure Within the PVC Al interphase Within the top coat C-O & C=O bonds in good sample are evidence of plasma treatment Bad sample exhibited adhesive failure at PVC - Al interface Interface contains plasticizer Little evidence of plasma treatment Tin stabilizer detected but probably not a significant cause of failure Review of plasma modification records revealed the power was ~5X too low for bad sample AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 16

XPS/ESCA Summary XPS can detect and quantify all elements except for H and He, and provide chemical state information; making it a powerful survey analysis technique AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 17

Analytical Modes of SIMS Dynamic SIMS Static SIMS Material removal Elemental analysis Profiling Ultra surface analysis Elemental or molecular analysis Analysis complete before significant fraction of molecules destroyed AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 18

Time-of-Flight SIMS: Basic Principles Pulsed Primary Ion Source Sample 3kV Detector Secondary Ions Tube length = l Ultra High Vacuum Chamber KE = q V = ½ mv 2 = ½ m l 2 /t 2 Measure spectrum in flight time: t 2 = ½ m l 2 /qv Convert time axis to mass: m = at 2 + b Light ions arrive at the detector first, with sequentially heavier ions following later in time. Each pulse of primary ions produces a full mass spectrum of secondary ions AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 19

Typical TOF-SIMS Data Spectra & Images Region 1 Spectrum Primary Ion Beam Chemical Map 1 m/z Total Ion Image Total Area Spectrum Chemical Map 2 m/z Region 2 Spectrum Sample m/z AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 20

TOF-SIMS Backside Transfer Background: Adhesion failure when coating a metallized polyolefin film. Questions: What caused failure? What was the source? Al metallization Layer with Irganox 1010 Layer without Irganox 1010 AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 21

TOF-SIMS Irganox 1010 Backside Transfer H C 17 H 25 O 2 C 14 H 23 O M = C 73 H 108 O 12 = 1176.78 amu M-H = 1175.78 m/z M-C 14 H 23 O = 969.61 m/z M-C 17 H 25 O 2 = 915.60 m/z M-H M-H = 1175.81 M-C 17 H 25 O 2 M-C 14 H 23 O AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 22

TOF-SIMS Backside Transfer Conclusions: Irganox 1010 was detected on both sides of the metallized film. Irganox 1010 migrated to the surface of the polymer layer during processing. Irganox 1010 transferred to the metallized surface during reroll/storage. AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 23

Ghost Image Background: Refrigerated food package exhibited ghost printing due to water condensation Film was stated to be a polyolefin Questions: What caused water condensation? AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 24

XPS Ghost Image Survey Spectra Control Area Ghost Area Oxygen Carbon Oxygen Nitrogen Carbon Silicon 1200 1000 800 600 400 200 0 Binding Energy (ev) 1200 1000 800 600 400 200 0 Binding Energy (ev) Atomic Concentration of Elements Area C O N Si Control 84.8 15.2 - - Ghost 89.8 8.5 0.6 1.2 AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 25

XPS Ghost Image High Resolution Spectra Carbon Nitrogen Silicon Ghost Area Ghost Area Control Area Ghost Area O-C=O C-(O,N) C-(C,H,Si) C-N silicone 292 290 288 286 284 282 Binding Energy (ev) 408 406 404 402 400 398 396 394 Binding Energy (ev) 112 110 108 106 104 102 100 98 96 Binding Energy (ev) Carbon Functional Groups (atom%) Area C-(C,H,Si) C-(O,N) O-C=O Control 67.3 14.8 2.6 Ghost 83.1 5.7 0.9 AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 26

TOF-SIMS Ghost Image GMO-C 3 H 7 O 3 GMO-CH 3 O 2 GMO-OH Control Area GDO-OH 100 200 300 400 500 600 Control area is covered with glycerol monooleate AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 27

TOF-SIMS Ghost Image PDMS Ghost Area Stearamide +H PDMS GMO-OH GDO-OH 100 200 300 400 500 600 Ghost area also contains polydimethyl siloxane and stearamide AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 28

Ghost Image XPS results: Film surface was covered with a compound containing C-O and O-C=O groups. Contaminants in the ghost area were silicones and amines/amides. TOF-SIMS results: Film coating as glycerol monooleate Contaminants as polydimethyl siloxane and stearamide. Stearamide is localized to specific areas. Contaminants are from printing inks transferred during reroll/storage. AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 29

TOF-SIMS Summary TOF-SIMS is a very surface sensitive technique providing full Elemental and molecular analysis with excellent detection limits. AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 30

XPS: Quantitative elemental and chemical bonding analyses Sampling depth 1 to 10 nm (3 to 30 monolayers) Analysis of any vacuum compatible sample Often the first look technique for organic materials TOF-SIMS: Summary Compound identification Sampling depth ~1 nm (~3 monolayers) ppm detection of elemental surface composition Analysis of any vacuum compatible sample that is reasonably flat Rapid imaging with sub-micron spatial resolution AIMCAL - Oct 21, 2008 Copyright 2008 Evans Analytical Group LLC 31