Testing and inspection

In memory testing, what is the main purpose of making a map recording which bits at which addresses failed?

  1. ATo increase memory capacity
  2. BTo decide the chip's color
  3. CTo perform repair by replacing failing locations with redundant rows and columns, and to analyze failure causes
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Answer: C. To perform repair by replacing failing locations with redundant rows and columns, and to analyze failure causes

A fail bit map shows the positions of failing bits by address. It is used to compute redundancy repair, replacing failing rows or columns with spares, and the pattern of failures (single bits, whole rows, clusters and so on) also helps infer what kind of manufacturing defect is responsible.

  • A. Recording failures does not increase capacity.
  • B. It has nothing to do with color.
  • C. Correct. It is used for repair and failure analysis.
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More Testing and inspection questions

  1. When compressing scan test outputs, why must signals whose value (0 or 1) is undetermined in simulation (unknowns, X) be removed?
  2. In testing high-speed serial interfaces, which method loops the chip's transmitter output back to its receiver so the chip itself verifies communication?
  3. What is the technique called that dynamically changes test items or limits per chip or per lot based on intermediate results and statistics, such as from wafer test?
  4. In AD converter testing, what is the main purpose of inputting a slowly varying sine wave or similar and counting how often each output code appears (a histogram)?
  5. For a chip that failed scan testing, what is the process called that logically narrows down candidate fault locations from which outputs mismatched on which patterns?