Why a water fine filter can result in problems
Water that is used in microelectronics should contain no particles. Fine filters are widely used to improve wet etch equipment performance. The filter is expected to reduce the number of particles in the water.
The number of particles is defined by measuring the number of defects on a wafer.
Two experiments were conducted:
- A filter of 100 nm was instilled in the pure water system to reduce the number of particles and reduce the number of defects on the wafer. A positive result was received. The number of defects on the wafer reduces. The explanation of the improved performance is as follows: 100nm filter stops particles and improves the purity of the water.
- A filter of 10nm was installed in addition to a 100nm filter for the pure water system. It was expected that the water purity would be additionally improved and the number of defects on the wafer would be reduced. Nevertheless, the number of defects on the wafer increased. Replacement of the wafer of 10nm for the finer filter of 3 nm did not result in better performance.
The main question is - why do fine filters unexpectedly result in an increased number of defects?
What is the model of failure?
What is the solution?
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