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High precision fully automatic wafer grinding machine with two spindles and cassette-to-cassette operation.

Einsatzgebiet

Fully automatic front and backside grinding of semiconductor wafers up to 300 mm diameter.

Spindles

The machine is equipped with two independent spindles (ball bearing: up to 4.000 rpm, air bearing up to 6.000 rpm). One Spindle position can be equipped with a TWIN SPINDLE.

Fine downfeed

Each spindle is mounted on an independent slide. All parameters of each spindle is programmable independently.
Minimum infeed step is 0.1 µm.

Rotary Table

The air-bearing CNC indexing table transports the wafer between roughing, finishing and loading / unloading stations. The four rotary chucks are built into the table. Each vacuum chuck (all ceramic chucks) is mounted on a high precision spindle.

Handling

The basic configuration of the wafer handling consists of two stations integrated to the machine front and rear-sides. Each station has a central high-speed robot, a centering station and a cleaning station. The cassettes are located in the front-side station.

In-Process gaging

In-process thickness gauging is utilized to measure wafer thickness during grinding by using contact probes (differential measurement principle).

Since the control always knows the actual wafer thickness and wheel position, it can stop the infeed, when the required wafer thickness is reached. In this way, the optimum in thickness accuracy can be achieved.

Thus thermal influences and tool wear have no significant effects.

Wafer size	3 inch bis 300 mm
Spindles
Speed	100 - 4000 min-1 (ball bearing) / 100 - 6000min-1 (air bearing)
Output	4 kW
Grinding wheels	300 mm Diamant
Fine Infeed
Speed	0,001 - 50 mm/min
Min. step	0,1 µm
Resolution	0,1 µm
In-Process-Gaging
Range	1200 µm
Resolution	0,08 µm
Accuracy	0,1 µm
Rotary table
Number of chucks	4
Type of chucks	porous ceramics
Speed	5 - 417 min-1
Throughput	60 Wafer/h (dep. on process)
Accuracy
TTV	<1 µm
Variation	<1µm
Surface quality	Rmax = <0.14 µm (dep. on process)
Weight	6500 kg
Space	3600 x 5500 mm