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Probe Test Results for 5 wafers of Ultimate-2 sensors. Outline: Yield and wafer maps Summary. Yield and wafer maps – wafer 1,2. Vref2 high Vref2 low. Wafer 1: good: 35 73% bad: 10 21% (?): 3 6%. Wafer 2: good: 36 75% bad: 8 17% (?): 4 8%. Yield and wafer maps – wafer 3,4.
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Probe Test Results for 5 wafers of Ultimate-2 sensors • Outline: • Yield and wafer maps • Summary
Yield and wafer maps – wafer 1,2 Vref2 high Vref2 low • Wafer 1: • good: 35 73% • bad: 10 21% • (?): 3 6% • Wafer 2: • good: 36 75% • bad: 8 17% • (?): 4 8%
Yield and wafer maps – wafer 3,4 Vref2 high Vref2 low • Wafer 3: • good: 12 25% • bad: 35 73% • (?): 1 2% • Wafer 4: • good: 26 54% • bad: 19 40% • (?): 3 6%
Yield and wafer maps – wafer 5 Vref2 high Vref2 low • Wafer 5: • good: 35 73% • bad: 12 25% • (?): 1 2%
Summary • Probe testing of these 5 wafers took approximately 9 days • Sensor selection based on hot/cold pixel counting + visual inspection of threshold scan plots • Selecting sensors with <1% of bad pixels • The goal is to replace “visual inspection” with automated database queries using parameters such as: • Noise, FPN, threshold, and their distributions • From the 5 wafers tested (240 sensors), we have selected 136 (primary) + 15 (optional/backup) chips • Final sensor yield is ~63% • We are in the process of constructing 13 additional ladders using these sensors