An Advanced Probe Characterization Tool Outline

Transcription

1 An Advanced Probe Characterization Tool An Advanced Probe Characterization Tool for Online Contact Basics Measurements p June, 7th 2005, San Diego (CA) Oliv (Infineon Technologies AG, Munich, Germany) Mar, Prof. Dr. Ignaz Eisele (Universität der Bundeswehr, Munich, Germany) Oliv Mar Pro Page 1 p

2 Outline Motivation Existing Tools Schematic Realisation Components Calibration Exemplary Measurements Summary e 2 Outlook

3 Motivation Modelling contact basics Optimizing contact resistance Avoiding oxide / low-k crack generation Influence of vertical and lateral forces wrt Cres Investigation of pad materials (thickness, hardness, etc.) Analysis of oxide films Evaluating new probe types Investigating prober dynamics e 3

4 Existing Tools for Contact Force Measurement Single Probe Plunger in Probe Card Analyser Weighing Platform (only z-force) Piezoresistive force sensor in Probe Holder Micromechanical sensors Pad-integrated sensors Automatic Prober e 4

5 Requirement Specification 1. Realtime contact resistance measurements 2. Automatic contact point definition 3. Positioning Accuracy in xy-direction: ± 0.5 µm z-direction: ± 0.05 µm 3. Capable for mounting different probe card types 4. Simultaneous sensing of lateral and vertical forces in the range of 0.5mN. 10 N 5. Retainer for various samples (Al, Cu, SiO 2, chips, ) 6. Static and dynamic measurements 7. Microscope w/ video camera e 5 8. Optional test under variable environment gas (O 2, N 2, ) 9. Optional test with variable probing temperature ( C)

6 Tool Schematic Camera Probe Holder Probe Contact Resistance Controller F T Sample u x F N Force Sensor u y u z xyz-stage e 6

7 Manufacturing Drawing Prober Frame Y-Force Sensor Probe card Sample Sample holder Probe card hold M6 M4 199,9 Z-Force Sensor 222,25 +/- 6,5 Z-Stage e 7 xy-stage

8 General View Single-Probe Card Sample Holder e 8

9 Vertical Positioning Stage e 9

10 4-pole Cres Measurement Controller Card Supply Voltage Sense Line Wire Shielding (option Sense Line z-up / z-down Supply Voltage e 10 R contact Cu Clamp

11 Single Point x- and z-load Cell Special Feature: Off center load compensated e 11 Absolute Accuracy: x-direction: z-direction: Resolution: x-direction : z-direction : 21,6 mn 36 mn 0,36 mn 0,6 mn

12 Data Acquisition and Visualisation Software Options: Automatic amplifier recognition Sensor database available and expandable Graphical display Real-time Different interfaces supported (USB, Ethernet, GPIB, etc.) MS Windows XP Measurement data exported in commonly used formates (e.g. ASCII, EXCEL,.) e 12

13 Calibration Method F x =c (x+ x) Output voltage m 2 g F z = m g m 1 g Sample Holder Sensor Force e 13

14 Calibration Realisation e 14

15 Exemplary Measurements with a Cantilever Probe e 15

16 Cantilever Probe used for Demonstration 0,25 0,20 Force in N 0,15 0,10 0,05 z-force x-force e 16 Source: MJC 0, Overdrive in µm

17 z-stage Profile Overdrive in µm Max. OD z-up Velocity z-down Velocity Holding time Delay time -10 e ,0 2,0 4,0 6,0 8,0 10,0 12,0 14,0 16,0 18,0 20,0 Time in s

18 Measurement on Gold Wafer (max. OD = 50µm) Force Z-Direction CH=3 Force X-Direction CH=4 Contact Resistance CH= Max. stage speed: 10µm/s Contact Force in mn Contact Point Time Sample Rate: 100Hz 0 e 18

19 Measurement on Aluminum Wafer (max. OD = 50µm) Force Z-Direction CH=3 Force X-Direction CH=4 Contact Resistance CH= Max. stage speed: 10µm/s Contact Force in mn Time Sample Rate: 300Hz 0 e 19

20 Probe Parameters vs. OD on Gold , ,0 100 z-force 8,0 80 7,0 Contact Force in mn Max. x-force Min. x-force 6,0 5,0 4,0 3,0-40 2,0-60 Min. Cres 1,0 e , Overdrive in µm

21 Probe Parameters vs. OD on Aluminum , , z-force 8,0 7,0 Contact Force in mn Max. x-force 6,0 5,0 4,0 3, Min. Cres Min. x-force 2,0 1,0 e Overdrive in µm 0,0

22 Cres Distribution 1,4 1,2 1 OD: 70µm Max. stage speed: 10µm/s 10 Touchdowns max min Contact Resistance 0,8 0,6 0,4 avg 0,2 0 Alu Pad Material Gold e 22

23 Quasi-Statical Measurement on Gold 14 3,5 Max. stage speed: 1µm/s z-force 3 8 2,5 Contact Force in mn Cres 2 1,5 1-2 e x-force Time in s Sample Rate: 300Hz 0,5 0

24 Summary A novel tool was demonstrated real-time measurements of lateral, vertical forces and contact resistance External noise must be minimized to improve accuracy Capable to all probing technologies Preliminary results show, that Contact resistance on Au more stable than on Al (Oxide Film?) Change of sign of lateral force during z-up/-down for cantilever probe Coefficient of friction between 0.2 and 0.5 (material dependent) Average Cres and distribution on Au smalller than on Al Holm Theory to be verified e 24

25 Next Steps Elimination of disturbing factors (cabling, acoustic noise, ESD, vibrations) Labview Programming of z-stage Image processing software for microscope Verification of contact resistance model ( Holm Theory ) Investigation of different probe types (vertical, MEMS, etc ) Influence of dynamics Analysis of new pad materials Oxide / low-k crack generation and avoidance e 25 Automated x- and y-stage control