Status of Pixel Test Niigata University/RIKEN Kohei Fujiwara

Current status Prober at RIKEN has been set up in Wako. –17 wafers were probed completely at CERN. –18 th wafer is under probing at RIKEN. –Currently, we have 501 class1 chips. –We need 600 chips. Kohei has just learned how to probe ladders at CERN.

RIKEN Prober Prober at RIKEN is working in our clean room. –The temperature is 20. –The humidity is 70%. (It will be improved.)

Current status of wafer probing We have 501 Class1 chips. The yield rate is 33.6%. The most of problem chips were recovered. It depends on the condision of top of needles. They needed to includes VDD_Analog. 100 chips are expected with 4 wafer in 33% yield.

Current status of wafer probing 2 Pixel existence rate on Class 1 chips The most of pixels work on each chip. The frequency of dead pixel appearance The most dead pixels are in around test columns. No.1, No.9, No.17 and No.25 Test columns 100%

Current status of wafer probing 3 Mean threshold of Class 1 chips is 1508e e - in 200μm Silicon by MIP. Mean noise of Class 1 chips is 116e -.

Ladder Test I have probed 4 PHENIX ladders at CERN. We check bump bonding condition with β source. Probing takes about 30 minutes. Only 1 senser assembly has only 1 noisy pixels on 4 th chip of Ladder No.4. A noisy Pixel

Ladder Test 2 The other ladders are good. –Ladder No.1 Some missing bumps on 4 th chip. Bump bonding error

Ladder Test 3 2 nd Ladder Bump bonding error 3 rd Ladder

Ladder Test 4 Minimum threshold of one sensor assembly is 3089e -. Noise value is 284e -. Bump bonding error map –It seems that the error happens easily at the bottom corner on the left corner. Missing bumps Column Row

Summary Prober at RIKEN is working in Wako. –Wafer probing is continuing. –I have just probed up to No.59 on 17 th wafer. 17 readout-chip wafers have been probed. –501 Class1 chips are obtained. 4 PHENIX ladders have been probed. –Some missing bumps and a noisy pixel. –More than 99% pixels are working. We will start probing PHENIX ladder at RIKEN by the end of June.