CMP and cleaning

What is a correct design countermeasure to the CMP removal amount varying with pattern density within a chip?

  1. AChanging the chip's color
  2. BPlacing dummy patterns to make pattern density uniform
  3. CReducing the number of patterns
Show answer and explanation

Answer: B. Placing dummy patterns to make pattern density uniform

Polishing proceeds differently in dense and sparse areas, causing thickness variation. Placing dummy patterns in empty areas at the design stage to equalize density makes the thickness after CMP uniform. It is an example of design and manufacturing working together to raise yield.

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More CMP and cleaning questions

  1. What is the approximate size of the abrasive particles in CMP slurries?
  2. What is the main purpose of diluting chemicals or using functional water in recent cleaning processes?
  3. What is the main purpose of cleaning the back and edge (bevel) of wafers?
  4. What is the main reason wafer cleaning is considered important in semiconductor manufacturing?
  5. Which correctly describes how many times cleaning is performed across the whole LSI manufacturing flow?