MAT-CS. Materials Characterization Services. Using Surface Analysis Techniques to Solve Packaging and Interconnect Problems.

Transcription

1 MAT-CS Materials Characterization Services Using Surface Analysis Techniques to Solve Packaging and Interconnect Problems Scott Baumann February 10, 2015

2 MAT-CS Company Overview Materials Characterization Services Broker of Analytical Services Partner with over 150 analytical labs Bulk Analysis Microscopy Surface Analysis Polymers Liquids/Gases Electrical Complete listing of techniques at Experienced Scientists 32 years of analytical experience Expert in experiment design and technique selection Objective and Independent Able to select the most appropriate technique/lab for each analysis Able to offer competitive pricing through multi-lab comparison Materials Characterization Services ~ 2

3 MAT-CS Materials Characterization Services Presentation Objectives Many Intractable Packaging and Interconnect problems can be solved if proper methods are applied SEM/EDS and FTIR are readily available and widely applied test methods, but are limited in sensitivity and resolution Other test methods are available that can extend our analytical reach, providing crucial information EAG labs is a leading provider of high end analytical testing (thanks for the slides!) Materials Characterization Services ~ 3

4 Introduction: Common Methods SEM/EDS Analysis Widely Applied & Available But! Limited spatial/depth resolution No organic information Silicon Aluminum 100 um 100 um

5 Electron Beam Sample Interaction Secondary Electrons Backscattered Electrons Primary Electron Beam Auger Electrons Å >Atomic No. 3 Sample Surface Characteristic X-rays > Atomic No. 4 <1-3 mm Volume of Primary Excitation Copyright 2006, Evans Analytical Group LLC 5

6 Auger Electron Spectroscopy AES

7 AES AES provides excellent surface sensitivity and small spot size Copyright 2014 Evans Analytical Group 7 ~

8 Key Applications Particles and small area analysis Particles and features as small as 25 nm can be analyzed Sub-monolayer analysis Films too thin for EDS Thin film elemental analysis Sampling depth to a micron or more with sputtering Semi-quantitative (Quantitative with standards) Copyright 2014 Evans Analytical Group 8

9 Typical Data Secondary Electron Image Survey Spectra Elemental Images Copyright 2014 Evans Analytical Group 9

10 Example: Thin Contamination Layer den(e)/de den(e)/de On metal line SEM image C Al Ti TiN/Al lines on SiO 2 Green=Ti Red=Al Ti+N O Kinetic Energy (ev) On defect AES map Al C N F Al O Auger analysis shows the thin residue is an Al flake, probably originating from the etch chamber Kinetic Energy (ev) Copyright 2014 Evans Analytical Group 10

11 Subsurface Analysis: Depth Profiling Ion milling (sputtering) is used to remove material only! Auger analysis is performed on the surface at the bottom of the sputtered crater, and is independent of the sputtering process. Copyright 2014 Evans Analytical Group 11

12 Example: Bond Pad Failure Good Bond Pad Normal wire bond strength Bad Bond Pad Poor wire bond strength Al oxide ~4 nm thick Al oxide ~160 nm thick Copyright 2014 Evans Analytical Group 12

13 AES Summary Strengths Extremely Surface sensitive (2nm) Excellent depth resolution when profiling Small spot size (10nm) Limitations Best quantification requires standards Insulators are difficult Samples must be vacuum compatible Copyright 2014 Evans Analytical Group 13

14 Surface Organic Techniques FTIR XPS TOF-SIMS

15 Overview: Organic Methods These techniques provide both organic and inorganic information, offering elemental and/or molecular characterization depending on the technique. These techniques are unique in providing direct chemical bonding information. There are hundreds of thousands of organic compounds, mainly consisting of combinations of C, H, O and/or N. The chemical bonding information can be invaluable for characterizing these organic materials. Copyright 2014 Evans Analytical Group 15

16 Organics: Common Methods White Powder on Electrical Pins Copyright 2014 Evans Analytical Group 16

17 % Transmittance FTIR Analysis: Widely Appied % Transmittance FTIR Spectra White powder Reference SOLDER FLUX Wavenumbers (cm -1 ) Wavenumbers (cm -1 ) Copyright 2014 Evans Analytical Group 17

18 X-Ray Photoelectron Spectroscopy/ Electron Spectroscopy for Chemical Analysis XPS/ESCA

19 XPS XPS can detect and quantify all elements except for H and He, and provide chemical state information; making it a powerful survey analysis technique Copyright 2014 Evans Analytical Group 19 ~

20 Key Applications Characterization of stains and discolorations Compositional analysis of powders and residues Evaluation of cleaning processes Determination of oxidation state and oxide thickness of alloys (e.g., electropolished stainless steels) and semiconductor materials Depth profile analysis of thin films for matrix level constituents and composition. Copyright 2014 Evans Analytical Group 20

21 XPS Process (Photoelectric Effect) X-ray Copyright 2014 Evans Analytical Group 21

22 XPS Technique Typical analysis modes: Survey analysis: full energy range scan at highest sensitivity Identifies and quantifies elements at surface High resolution analysis: narrow scans at higher energy resolution than surveys Identifies chemical state from peak position and peak shape Depth profile analysis: atomic composition as a function of depth Determines compositions of thin films with good accuracy Copyright 2014 Evans Analytical Group 22

23 Contamination on Silicon Wafer Survey analysis comparing discolored area to an adjacent reference area Copyright 2014 Evans Analytical Group 23

24 Contamination on Silicon Wafer High resolution scan of the Al2p signal detected on the haze Copyright 2014 Evans Analytical Group 24

25 Sputter Depth Profiling of Insulating Materials Anti-reflective (AR) coating on glass AR coatings modify reflection characteristics and are useful in photolithography applications and to enhance the performance of optical devices such as LEDs O SiO 2 TiO 2 SiO 2 TiO 2 Glass substrate Si Ti Ca Copyright 2014 Evans Analytical Group 25

26 Summary Strengths Very surface sensitive (2nm) Elemental identification of all elements except H and He Chemical state identification (oxidation state) Quantitative analysis Can analyze insulating samples Limitations Detection limits typically ~500 ppm Smallest analytical area ~10 µm Limited organic information UHV technique Copyright 2014 Evans Analytical Group 26

27 Time-of-Flight Secondary Ion Mass Spectrometry TOF-SIMS Static SIMS

28 TOF-SIMS TOF-SIMS is a very surface sensitive technique providing full elemental and molecular analysis with excellent detection limits. Copyright 2014 Evans Analytical Group 28

29 Key Applications Surface characterization of organic and elemental materials Mapping distributions of surface species Contaminant identification ( < ppm) Elemental Molecular Failure analysis Adhesion Bond Pads Coatings Evaluation of cleaning processes (QA/QC) Identification of stains, discolorations, and hazes Copyright 2014 Evans Analytical Group 29

30 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 Copyright 2014 Evans Analytical Group 30

31 Time-of-Flight SIMS: Basic Principles Pulsed Primary Ion Beam Sample Detector 3kV Secondary Ions 3 kev= 1/2 mv 2 Measure spectrum in flight time: t = k(m) 1/2 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 Copyright 2014 Evans Analytical Group 31

32 Residue on Flat Panel TFT Photo of surface Mass spectrum Total ion image C 3 H 9 Si image (silicone) C 2 H 3 image (general hydrocarbon) Copyright 2014 Evans Analytical Group 32

33 Counts Organic Contamination on Si Wafer Positive ion spectrum m/z Copyright 2014 Evans Analytical Group 33

34 Reference Spectra from Compound Data Base C CH 2 O O C CH 2 CH 2 C(CH 3 ) 3 OH + CH 2 C(CH 3 ) 3 OH Irganox 1010 C(CH 3 ) C(CH 3 ) m/z O C OH COOC 8 H C O 133 COOC 8 H 17 Diisooctyl phthalate (DOP) m/z Copyright 2014 Evans Analytical Group 34

35 Common Organic Surface Contaminants Detected by TOF-SIMS Species Possible Sources Siloxane, (Polydimethylsiloxane, PDMS) Polyethylene oxide or polyethylene glycol Fatty acids Glycerides Phosphates, sulfates, etc. Phthalate, etc. Machine lubricant, release agent, tape Surfactants, plasticizer, printing inks Finger oils, lubricants, polymer additives Soap, polymer additives, releasing agents Cleaning reagent, surfactants, additives Polymer additives, plastic parts, containers Copyright 2014 Evans Analytical Group 35

36 Strengths TOF-SIMS Summary Extremely surface sensitive (<1nm) elemental and molecular information on thin (submonolayer) organic films/contaminants survey analysis ppm detection limits small spot size (0.2 µm) and mapping analyzes insulators and conductors Limitations organic information can be limited vacuum compatibility required at times, too surface sensitive Copyright 2014 Evans Analytical Group 36

37 A Wide Variety Test Methods Copyright 2014 Evans Analytical Group 37 ~

38 MAT-CS Materials Characterization Services Conclusions While many problems can be solved using commonly available test methods like SEM/EDS and FTIR, in some cases more horsepower is needed. There are many high end methods available that can provide further insight into difficult problems. With guidance from experts even undetectable contaminants can be measured and impossible problems can be solved. Materials Characterization Services ~ 38