Recent Development Work in IC Bond Pad Structure and Circuit Under Pad. Stevan Hunter

Transcription

1 Recent Development Work in IC Bond Pad Structure and Circuit Under Pad Stevan Hunter Presented to IMAPS Student Chapter, UI, 29 SEP

2 Who did the work? Stevan Hunter Principal Reliability Engineer, ON Semiconductor, Pocatello, ID PhD Student, ISU; IMAPS member (Project started in late 2008, early work constituted MS project, May 2010) Steven Sheffield, Cesar Salas, Jason Schofield, Jose Martinez, Kyle Wilkins, Marco Salas Undergraduate student interns, Brigham Young University Idaho 1 per trimester starting in Fall 2009 (Work is contuing with Jonathan Clark, Fall 2011) Bryce Rasmussen, Troy Ruud, many others... ON Semiconductor ** Work supported by ON Semiconductor ** 2 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

3 Scope of Today s Presentation Summarizing 3 presentations / publications in 2011, relating to 0.18µm CMOS IC Technology, and other CMOS with Al metallizations 1. Hunter, et al, Use of Harsh Wafer Probe to Evaluate Various Bond Pad Structures, IEEE SWTW, Jun Hunter, et al, Use of Harsh Wire Bonding to Evaluate Various IC Bond Pad Structures, IMAPS EMPC2011, Sep Hunter, et al, Physically Robust Interconnect Design in Bond Over Active Circuitry for Cu Wire Bonding, IMAPS / SEMI Wirebonding Workshop, Jul 2011 (Two new papers to be presented at IMAPS 2011 in Oct) Martinez, et al, IC Bond Pad Structural Study by Ripple Effect, IMAPS 2011, Oct 2011 Hunter, et al, Bond Over Active Circuitry Design for Reliability, IMAPS 2011, Oct Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

4 Outline Traditional IC Bond Pads Wafer Probe Wirebonding The Cratering Test Mechanism of metals deformation and SiO 2 cracking Need for improved bond pad structures, BOAC / CUP Findings from harsh probing experiments Findings from harsh bonding experiments Design methodology for robust BOAC pad structures Pad Design Solution examples Summary 4 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

5 Integrated Circuit Bond Pads Example packaged IC s (from internet) IC die example (photo: USC) 5 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

6 Wafer Probe (Electrical Test) Probe needles simultaneously touch all bond pads of the die in order to perform electrical testing of the die. Each touch damages the pad Al surface, leaving a probe mark 6 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

7 Simplistic View of Probing (Cantilever probe tips) wafer: bond pad Wafer comes into contact with the Probe Tip wafer Z-up Wafer moves up into Overdrive position for test, scraping the pad Al and causing a Probe Mark 7 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

8 Probed Pad Reliability Concerns Electrical OverStress (EOS) or Electrostatic Discharge (ESD) receives much attention and is usually eliminated in manufacturing Probe mark interferes with bondability probe mark area too large probe mark gouge too deep (too little Al remaining) Top intermetal dielectric (top IMD) cracks beneath pad Al crack weakens films adhesion and intermetallic bond strength crack in IMD causes crack in TiN barrier allows Al, Au, Cu diffusion into the circuitry crack may propagate during use (latent defect) physical weakening of pad and bond structure crack may extend to another metal feature electrical leakage or short crack is visible to a customer who does die analysis obvious reliability issue to customer 8 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

9 2 Mils Overdrive 1 TD 2 TDs 3 TDs 4 TDs 5 TDs 6 TDs Pad #2 SLM Pads 4 Mils Overdrive 1 TD 2 TDs 3 TDs 4 TDs 5 TDs 6 TDs Pad #2 SLM Pads 9 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

10 Probe Mark Analysis by AFM & Cratering Test 8 9 pad 8 pad 9 10 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

11 Probe Mark Analysis by FIB Cross Section FIB through the probe mark center reveals gross cracking, with breakage of the top IMD and deformation of TM(-1) 11 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

12 Bond Pads and Wirebonding It is typical for 25µ Au wire or 20µm Cu wire to be bonded to each pad, and the wire connects to a lead on the package Illustrations of ball bonds on bond pad structures (from ASE, Sep2011) 12 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

13 Wirebonding A ball is formed at the end of a Au or Cu wire, then the ball is squished onto the Al pad surface and welded by ultrasonic energy Upper photos: 13 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

14 Wirebonding / Pad Reliability Concerns Bond ball poor adhesion Bond stability against corrosion and diffusion Au-Al IMC issues Resistance increase over time Loss of adhesion over time IMD cracks (critical if BOAC / CUP pad) Bending and deformation of BOAC / CUP metal circuitry ESD protection (circuitry under pad in BOAC / CUP) Bond wire adhesion to package lead Bond wire integrity against corrosion or oxidation Bond wire stiffness to combat bending during plastic molding 14 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

15 Bonded Pad Issues and Analysis Methods 1. Bond Pull Strength test (BPS) Hook the wire loop and pull up until breakage Record the breaking force and failure mode (accepted spec limits) Ball may come off the pad at a low force due to poor adhesion Ball may pull out a chunk of the pad as it pulls off (pad divot or crater) 2. Ball Shear test (BS) Shear (bulldoze) the ball off the pad Record the breaking force and failure mode (accepted spec limits) Ball may come off the pad at a low force due to poor adhesion Ball may pull out a chunk of the pad as it pulls off (pad divot or crater) Note that when the films adhesion is strong and the ball is stiff, BS test will break something in the structure interpretation of results may be difficult 3. Cratering Test Etch away the ball and pad Al, then optically inspect for damage Cracks, lifting barrier film, divots and craters, and ripple effect SEM inspection, FIB or cross section polish SEM 15 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

16 Traditional bond pad: 4-level metal example A 4-level metal pad structure within the pad window is illustrated in concept: Al metallization: TiN / Al(0.5%Cu) / TiN, W vias, SiO 2 dielectric sheets of metallization at all levels via arrays connecting the metals SiO 2 dielectric surrounding Pad Al (MT) Top Vias MT(-1) Vias MT(-2) Vias MT(-3) (Periphery of pad structure, passivation, Si devices, etc. are not shown) 16 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

17 Pad Cracking: Process Flow Wafer probe (electrical test) Wirebond Packaging Operation 1. Compressive stress from probe force 2. Lateral stress from scrub 3. Multiple touchdowns 1. Compressive stress from C/V + downforce 2. Lateral stress from ultrasonic Cracks initiate, then propagate (crack) 1. Thermal cycling 2. Stresses from packaging 1. Use conditions 2. Thermal cycling 17 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

18 Cratering Test (1) Cratering Test (removal of bond ball and pad Al, then visual inspect) Etch to dissolve or undercut the bond ball, and etch away the pad Al, but purposely leave some of the TiN barrier film if possible visually observe top SiO 2 cracking visually observe other damage: lifting barrier other loss of adhesion divots in top IMD craters 18 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

19 Wafer Probe Cratering Test Cratering test removes the pad Al and the probe mark Usually etch only the Al to leave TiN barrier easier to see the cracks (highlighted in red below) Can also overetch the TiN to reveal etch damage in the underlying metal layer Pad 1 Pad 2 Pad 3 Pad 4 Pad 5 Pad 6 Probe Mark Normal Etched Over Etched 19 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

20 Cratering Test (2) Enables comparison between standard and harsh wirebond, and various pad structures Top Vias No Top Vias Au ball bond Harsh Au ball bond 20 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

21 Cratering Test (3) optical ripple effect deformation in underlying metal interconnect (verify by FIB or XSEM) Au ball bond Harsh Au ball bond FIB cross section of traditional bonded pad test structure Al Al Top SiO 2 SiO 2 21 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

22 Cratering Test (4) Not all issues can be seen in cratering test cannot detect weakened locations may not see cracks in SiO 2 if the TiN barrier is not broken cannot detect partially cracked locations on the bottom of the SiO 2 22 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

23 Damage relating to top vias top vias participate in SiO 2 cracking, giving traditional pads with top vias the worst record for cracking lifting TiN, SiO 2 divots, and craters are much more likely with top vias cracks propagate from via to via an example of lifting barrier, relating to top vias 23 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

24 Al Deformation & SiO 2 Cracking Basic issue with traditional pad designs: Large mechanical stress into brittle SiO 2 film over ductile Al film Underlying Al deforms into local hills and valleys, which bends the SiO 2 which cracks when its tensile fracture strength is exceeded Cracks may initiate in the top of the SiO 2 above deformed Al hill Cracks may initiate in the bottom of the SiO 2 in deformed Al valley Significant stress may be applied in wafer probing Significant stress may be applied in wirebond, especially Cu Additional stress may be applied in packaging Cracks and weak regions in the SiO 2 may go undetected, but remain a reliability concern 24 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

25 Pad Stack Design Leads to Pad Cracking Pad Window (probe and bond stresses here) Al SiO 2 Al SiO 2 Al SiO 2 Al SiO 2 Si 2.) SiO 2 bends and cracks 1.) Al film deforms into hills and valleys (TiN barrier layers not shown, for simplification) 25 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

26 Pad Stack Design Leads to Pad Cracking (2) Pad Window (probe and bond stresses here) Al SiO 2 Al SiO 2 Al SiO 2 Al SiO 2 Si 2.) SiO 2 bends and cracks 1.) Al film deforms into hills and valleys (TiN barrier layers not shown, for simplification) 26 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

27 Examples of Cratering Test Results Pad crack from ball bonding Latent damage from wafer probe revealed from bonding Barrier lifting, and divot in top IMD Pad ripple from ball bonding FIB cross section of divot. Sub-layer Al ripple caused the crack 27 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

28 Needs for Al SiO 2 Bond Pad Structures Need a methodology to accomplish the following together: Bond-over-active-circuitry (BOAC), 2 7 levels of metal Maximum pad design flexibility for small die size, Interconnect circuitry in all levels below the pad metal, (& ESD protection) pad anywhere is desirable Up to 6 wafer probe touchdowns Cu wirebond to replace Au wirebond Higher reliability No bending or deformation in sub-layers No cracks No other bonding issues Often cannot use thick top metal (MT) Decreased cost 28 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

29 Engineering Tradeoffs / Issues Metal bending and deformation in interconnects is not acceptable in BOAC / CUP Pad cracks are not acceptable in BOAC / CUP Traditional pad structure cracks easily from wafer probing Traditional pad structure cracks easily from wire bonding Thin top metal increases stress to reach underlying films Cu wirebond increases stress on the pad Al High number of probe touchdowns increases pad cracks Cannot add new layers or process steps Cannot introduce new materials or layer alterations No existing methods to solve these simultaneously Need methodology for more robust pads 29 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

30 Available Methods for Al SiO 2 Pads (1) 1. reduce the mechanical stress to the bond pad Al minimize touchdowns and force at wafer probe minimize stress at wirebond but, Cu wirebond still requires more mechanical stress than Au wirebond 2. modify the top of the pad to reduce the stress reaching the underlying pad structure thicker pad Al alter the barrier film add films to the pad top but, the above add cost and complexity, and adverse engineering tradeoffs; deformation and cracking are reduced but are not necessarily prevented in Cu wirebond 30 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

31 Available Methods for Al SiO 2 Pads (2) 3. modify pad structure features for a specific purpose change the pad metal topology to improve Au wirebond adhesion modify the top via pattern in or around the pad to prevent cracks or to contain the cracks within the pad window location eliminate top vias in the pad window to reduce cracking use vias in combination with specific metal patterns to strengthen remove metal features to reduce stress to devices beneath place dummy metal features for damping of bonding stress use specific connected bus structures suitable for BOAC use certain metal patterns to reduce pad capacitance use metal features to dampen the bonding stress But, no method or combination of these methods meets the needs for freeform design of BOAC with Al-based interconnects in all metal levels beneath the pad window, especially not for achieving pad structures robust enough for the increased mechanical stress of Cu wire bonding. 31 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

32 Findings from Harsh Probing Experiments Optimize probing parameters for reduced force as required Multiple touchdowns still pose some risk for cracking Presence of a full sheet of Al metallization beneath the pad dominates cracking behavior Top vias weaken the SiO 2 Thick pad Al reduces interconnect metal deformation and SiO 2 cracking Prevent pad cracks at wafer probe by preventing bending of top SiO 2 ; i.e. prevent deformation in underlying Al film Lower metal pattern density of interconnect layers, especially MT(-1) In particular, ensure small metal width between spaces, slots, or holes in MT(-1) (Cracks tend to occur where probe force is above MT(-1) areas) (Cracks tend to occur where probe scrub path transitions from MT(-1) space to MT(-1) metal in the pattern) 32 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

33 MT(-1) experimental design examples After cratering test, cracks are visible in the TiN barrier MT(-1) patterns can be seen, after removal of pad Al and TiN barrier film Examples of metal test patterns in MT(-1) full sheet, no vias under full sheet, no top vias, but dense vias under [ref: Hunter, et al; IEEE SWTW JUN 2011] 33 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

34 Harsh Probe Data Experimental Bond Pads Fraction of cracked pads vs metal pattern density in MT(-1) 34 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

35 Harsh Probing: Pads cracked vs MT(-1) pattern 35 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

36 Findings from Harsh Bonding Experiments (1) Harsh Bonding results are very similar to harsh probing results Pad structures crack due to high bonding stress, so we optimize for low stress in manufacturing Cu bonding stress is harsh regardless Simulate the same high stress by un-optimized Au ball bond recipe Presence of a full sheet of Al metallization in pad sub-layers dominates cracking behavior Top vias weaken the SiO 2 Thick pad Al reduces sub-layer interconnect metal deformation and SiO 2 cracking 36 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

37 Pad Al Thickness Reduces Sub-layer Deformation Cratering test ripple: Au ball bond on traditional pad structure 1µm pad Al 7% pads cracked 1.5µm pad Al 4% pads cracked 3µm pad Al 0% pads cracked 37 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

38 Findings from Harsh Bonding Experiments (2) Prevent pad cracks at bonding by preventing bending of top SiO 2 ; i.e. prevent deformation in underlying Al film Lower metal pattern density of interconnect layers, especially MT(-1) Presence of MT(-1) features and vias beneath may be beneficial, unless high pattern density Reduce metal width between spaces, slots, or holes Other Bonding cracks don t tend to interact with interconnect patterns Removal of metal in all layers beneath pad is unacceptable due to potential harsh bonding strain on devices beneath and increased cracking outside pad window Traditional reliability testing is not likely to reveal cracking issues 38 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

39 Summary: Bond Pad Structure Cracking Results Harsh Probing and Harsh Au Wirebonding Traditional Weakest No top Vias Slight improvement Missing MT(-1) More improvement Slotted MT(-1) Better Waffle MT(-1) Better Missing MT(-1) and MT(-2) Very good Missing MT(-1) Slotted MT(-2) Best Missing MT(-1) waffle MT(-2) Best Missing MT(-1, -2,-3) Strongest 39 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

40 Harsh Au Wire Ball Bonding Results pads analyzed in this experiment Pad test structure examples. These pads have Top Metal removed Indicates Pad Designs with TM(-1) Missing. 40 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

41 Au(1%Pd) 1 mil Wire Bond (Non-optimized Recipe, 2000 pads) Crater Test & Ball Shear Results for Different MT(-1) Pad Structures Only traditional pads exhibited consistent cracking for AuPd ball bond. 41 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

42 Cu 1 mil Wire Bond (2000 pads) Crater Test & Ball Shear Results for Different TM(-1) Pad Structures Only traditional pads exhibited consistent cracking for Cu ball bond. 42 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

43 Au & Cu Wirebond Reliability Test Results 1mil Au wirebond, and 1mil Cu wirebond rel tested in parallel, 3 different robust pad BOAC designs, electrically test I L 1 assembly lot (300 plastic packaged parts) each 0.8um Pad Al thickness on robust pad 2 Au bonds: large IMC growth, some voiding BPS BS Cu bonds: Al remaining under bond, very little IMC, no weakening or resistance increase more reliable for high temperature applications, don t need thick pad Al 43 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

44 Design of Physically Robust Pads >>> don t let the SiO 2 bend significantly during pad stress <<< Do this by preventing Al deformation beneath the SiO 2 Prevent Al hills and valleys, prevent plastic deformation Do this by lowering the metal pattern density in the metal sub-layers beneath the pad window, predominantly in MT(-1) Limit the maximum allowed metal width (or distance) between spaces, slots or holes in the metal sub-layers beneath the pad window, with the most restriction imposed in MT(-1) Vias beneath MT(-1) and MT(-2) features are encouraged Below: Example of how robust pad design guidelines may be specified MT Very thin nominal THICK MT(-1) density MT(-1) width MT(-2) density MT(-2) width (actual values are technology-specific) 0-50% dense, very narrow 25 75% dense wide 0-75% dense narrow 15-90% dense wider 0-85% dense not as narrow 15-95% dense widest 44 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

45 Examples of Robust Pad Design Solutions 1. 3LM BOAC, Au wirebond 2. 3LM Power Device, Cu wirebond 3. 4LM standard pad for design library, Au or Cu wirebond 45 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

46 Pad Design Challenge 1 3LM BOAC 3-level Metal, older CMOS technology, Very thin top metal Die area limit requires BOAC pads Freeform interconnect circuitry in M1 and M2 Some top vias required Need ESD protection circuitry under pad Traditional bond pads historically had issues with cracks in non-optimized probing and bonding processes, partly due to the very thin top metal 46 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

47 3LM BOAC Pad Design Solution 1 M1 and below for ESD protection circuitry under pad 93% M1 pattern density, mostly due to the natural spaces M2 sparse with only about 5% pattern density Top vias connect M2 to pad Pad electrical node conduction through dense vias outside pad window Successful product qualification, including extended reliability testing followed by wire pull, ball shear, and cratering tests No cracking found in harsh probing and harsh bonding tests with Au wire Issues with Cu wirebonding due to such thin top metal 47 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

48 Pad Design Challenge 2 3LM Power Device, Cu wirebond 3-level metal power device Thick top metal Cu wire bond Pad anywhere style BOAC Product failed qualification: Certain pads were having electrical shorts Caused by cracks in the top SiO 2 Pads with large area M2 features in the pad window had the cracks 48 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

49 Pad Design Solution 2 3LM Power Device, Cu wirebond DOE with a number of variations in lower metal density Various arrays of holes in M2 and M1 Or selected slotting in M2 and M1 And various via density changes between M2 and M1 Arrays of holes in M2 were most successful at preventing cracks Don t need holes in M1, only M2 Via placement had no effect Lowered M2 pattern density to 80% on large area features Uniform lower density in the pattern is a benefit of arrayed holes Completed full reliability qualification without issues (Other products, including 2LM and 3LM, have been improved by the same method, both Au and Cu wire) 49 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

50 Pad Design Challenge 3 Reduced area pad for design library Well established CMOS technology Nominal top metal thickness At least 4-levels of metal Standard robust pad design for no MT(-1) in pad window, and full ESD protection under the pad Provide options for designers: Ability for designer to add MT(-1) interconnects for BOAC Permit use of ESD protection devices outside the pad instead 50 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

51 Pad Design Solution 3 4LM standard pad for design library No MT(-1) in pad window MT(-1) and dense top vias for pad connection are outside pad window only Option for MT(-1) interconnect Simulated by bus structures with arrays of holes (75% pattern density in bus) Vias connecting MT(-1) to MT(-2) 4um wide bus structures traverse the pad window in MT(-2) for the various electrical nodes, about 50% pattern density ESD protection circuitry under pad, including the M1 circuitry Option to replace ESD circuitry under pad and use other qualified ESD protection circuitry as desired 3 pad designs qualified together Harsh probing, followed by harsh bonding tests with multiple wire types Standard and extended reliability qualification testing, with extra wire pull, ball shear, and cratering tests following the reliability stresses 1mil Au wirebonding 1mil Cu wirebonding 51 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

52 Summary Pad design challenges include various engineering tradeoffs Prior design methods for Al SiO 2 pad structures don t provide the needed solutions Basic BOAC / CUP pad design guidelines were developed based on extensive data: Various pad test structures Harsh probing Harsh Au wirebonding, AuPd, and Cu wirebonding Extended reliability testing, with physical pad tests following Ripple effect in the cratering test is valuable in assessing pad robustness Pad Al thickness is a less important parameter on a robust pad structure Examples of improved pad design in product solutions 52 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

53 Future Work Harsh Probing experiments are continuing More test structures in more CMOS technologies Different style probe cards Harsh Bonding experiments are continuing More test structures in more CMOS technologies Reliability testing Au and Cu wirebonded parts with new pad structures Implementing improved pads and Cu wirebonding on products Finite element modeling (FEM) to investigate robust pad physical principles Seeking to refine bond pad Design Rules for BOAC / CUP 53 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

54 W stud pressing on Al over SiO2 Basic 3D model Von Mises Stress after downforce 54 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

55 3LM Bond Pad with W probe touching it. Films, top to bottom, are: 1um pad Al, 1um SiO2, 0.5um Al M2, 1um SiO2 IMD1, 0.5um Al M1, 1um SiO2 ILD, 600um Si 55 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

56 Equivalent strain for 1E-5 un probe force on 3LM bond pad. High strain points at the edge of the probe, with strain continuing down through the layers. 56 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

57 Probed Bond Pad FIB Cross Section 57 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

58 2D Surfaces Sketch (YZ & ZX symmetry) with 5um radius flat tip 58 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

59 5u radius flat probe tip 100GPa pressure (all hidden except top SiO2 and MT(-1) Al) 59 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

60 Bonding Ripple in bond pad layers 60 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

61 Al splash in Cu ball bonding 61 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

62 2D Surfaces Sketch (YZ & ZX symmetry) with 60um radius bond ball 62 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011

63 Hiding everything but the top SiO2 and MT(-1) 63 Stevan Hunter Recent Development Work in IC CUP 29 Sep 2011