Understanding Contact Resistance between

Understanding Contact Resistance Between
Different Probe Tips and Contact Surfaces
Brett Crump
Sam Waggoner
Applied Precision
June 14, 2000
5/22/2000
1

Contact Resistance Process
Variables Examined
• Low Forcing Current versus High
• Probe Contact Force (overtravel)
• Probe Tip Geometry and Scrub
• Contact Surface Material
• Instantaneous Repeatability (Static)
and Multiple Interface
Reproducibility (Dynamic)
5/22/2000
2

Test Apparatus and Setup
• PrecisionPoint PRVX 2
– All data was gathered on the same
system
– Different probe card
motherboards/PMBs were used
– Four-wire Kelvin System
– Single Expert Operator
– Environment was a Semi Test Floor
5/22/2000
3

Test Apparatus and Setup
(continued)
• Probe Cards
– Membrane
– Vertical
– Radius-Tip
– Tungsten-Rhenium
• Contact Surfaces
– Tungsten-Carbide Checkplate
– Gold Plate
– Wafer
5/22/2000
4

Static Cres (Checkplate)
10
9
Resistance (Ohms)
8
7
6
5
4
3
2
1
0
5/22/2000
5
MEMBRANE RADIUS-TIP TUNG-RH VERT
Probe Card

Dynamic Cres (Checkplate)
8
7
6
Resistance (Ohms)
5
4
3
2
1
0
5/22/2000
6
MEMBRANE RADIUS-TIP TUNG-RH VERT
Probe Card

Static Cres (Gold Plate)
3.5
3
Resistance (Ohms)
2.5
2
1.5
1
0.5
0
5/22/2000
7
MEMBRANE RADIUS-TIP TUNG-RH VERT
Probe Card

Dynamic Cres (Gold Plate)
3
2.5
Resistance (Ohms)
2
1.5
1
0.5
0
5/22/2000
8
MEMBRANE RADIUS-TIP TUNG-RH VERT
Probe Card

Static Cres (Wafer)
7
6
5
Resistance (Ohms)
4
3
2
1
0
5/22/2000
9
MEMBRANE RADIUS-TIP TUNG-RH VERT
Probe Card

Dynamic Cres (Wafer)
6
5
Resistance (Ohms)
4
3
2
1
0
MEMBRANE RADIUS-TIP TUNG-RH VERT
Probe Card
5/22/2000
10

Effects of Overtravel on Cres
(Checkplate)
6.5
Average Resistance (Ohms)
6
5.5
5
4.5
4
0.5 1 1.5 2 2.5 3 3 2.5 2 1.5 1 0.5
Overtravel (Mils)
MEMBRANE
RADIUS-TIP
TUNG-RH
VERT
Poly. (VERT)
Poly. (RADIUS-TIP)
Poly. (TUNG-RH)
Poly. (MEMBRANE)
5/22/2000
11

Cres Deviation with Overtravel
(Checkplate)
1
0.9
Standard Deviation (Ohms)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0.5 1 1.5 2 2.5 3 3 2.5 2 1.5 1 0.5
MEMBRANE
RADIUS-TIP
TUNG-RH
VERT
Overtravel (Mils)
5/22/2000
12

Effects of Overtravel on Cres
(Gold Plate)
4.5
Average Resistance (Ohms)
4
3.5
3
2.5
2
1.5
1
0.5
MEMBRANE
RADIUS-TIP
TUNG-RH
VERT
0
0.5 1 1.5 2 2.5 3 3 2.5 2 1.5 1 0.5
Overtravel (Mils)
5/22/2000
13

Cres Deviation with Overtravel
(Gold Plate)
1
0.9
Standard Deviation (Ohms)
5/22/2000
14
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0.5 1 1.5 2 2.5 3 3 2.5 2 1.5 1 0.5
Overtravel (Mils)
MEMBRANE
RADIUS-TIP
TUNG-RH
VERT

Effects of Overtravel on Cres
(Wafer)
8
7
Average Resistance (Ohms)
6
5
4
3
2
1
MEMBRANE
RADIUS-TIP
TUNG-RH
VERT
0
5/22/2000
15
0.5 1 1.5 2 2.5 3 3 2.5 2 1.5 1 0.5
Overtravel (Mils)

Cres Deviation with Overtravel
(Wafer)
1.8
Standard Deviation (Ohms)
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
MEMBRANE
RADIUS-TIP
TUNG-RH
VERT
0
5/22/2000
16
0.5 1 1.5 2 2.5 3 3 2.5 2 1.5 1 0.5
Overtravel (Mils)