E0286 â VLSI Test VLSI Test
E0286 â VLSI Test VLSI Test
E0286 â VLSI Test VLSI Test
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Importance of DPPM<br />
- Theoretical example:<br />
- Sample of 10^6 devices.<br />
- 10000 are faulty.<br />
- 100 escape manufacturing test screen.<br />
- Yield = 99%. DPPM = 100.<br />
- Coverage = 99%, (assuming equal distribution and occurrence of modelled<br />
faults).<br />
- Practical case:<br />
- Yield much lower. More faulty devices.<br />
- Coverage much lower. More test escapes.<br />
- Modelled faults do not occur uniformly.<br />
- Several non-modelled faults also occur.<br />
- Beta quality of silicon test program.<br />
- Result: DPPM of 10000s. On ramp, DPPM of 100s.
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