Polishing Pad Rise Control via Residue Measurement
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Solution Overview
Problem
The existing methods for raising polishing pads in wafer polishing processes often result in scratches and significant degradation of particle levels, especially during the early stages of polishing, due to insufficient pad rise, which worsens with larger machines.
Innovation Solution
A method involving dummy polishing and residue measurement using a foamed urethane resin pad, where dressing is followed by dummy polishing to build up residues, and then measuring these residues to determine if the pad has sufficiently risen, using a reference value based on the pad's life expectancy, to ensure proper pad rise and prevent early-stage degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If dressing is performed to raise the polishing pad, then the surface roughness and thickness are adjusted, but the particle level degrades in the polishing pad life early stage due to insufficient rise
Solution Approach 1:
The invention performs preliminary actions (dummy polishing and residue accumulation) before actual polishing to ensure the polishing pad is sufficiently risen. By accumulating polishing residues through dummy polishing and then removing them, the pad achieves proper rise and surface formation, preventing particle level degradation during early polishing stages.
Solution Approach 2:
The invention introduces a feedback mechanism by measuring the amount of polishing residues and comparing it against a reference value. This feedback loop determines whether the polishing pad has risen sufficiently, allowing adjustment of the raising process to ensure optimal pad condition before production polishing begins.
2Reliability
If dummy polishing is performed to raise the polishing pad, then the particle level improves, but the polishing time increases
Solution Approach 1:
The feedback mechanism measures polishing residue amounts and compares them to reference values to determine when the pad has risen sufficiently. This prevents excessive dummy polishing time by stopping the process once the target rise level is achieved, optimizing the balance between pad quality and process time.
Solution Approach 2:
The invention replaces extended mechanical dummy polishing with a measurement-based approach. By using fluorescent X-ray analysis to detect polishing residues and comparing against reference values, the system substitutes time-consuming trial polishing with a precise measurement and judgment system.
3Productivity
If the polishing machine size increases, then the processing capacity increases, but the likelihood of scratch generation and particle level degradation increases
Solution Approach 1:
The invention performs preliminary pad raising actions before production polishing on large-capacity machines. By ensuring the polishing pad is sufficiently risen through dummy polishing and residue accumulation prior to actual wafer processing, the system prevents scratch generation and particle level degradation that are more likely to occur on larger polishing machines.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively raises the polishing pad until it is sufficiently risen, preventing scratches and degradation, thus improving particle levels during the early stages of polishing and reducing unnecessary dummy polishing time.
Implementation Method 1
the amount of polishing residues is measured by detecting a signal containing a Si—Kα ray from a fluorescent X-ray spectrum which is obtained by a fluorescent X-ray analysis method
Data Source
AI summary
A method for raising a polishing pad for polishing a silicon wafer, wherein a polishing pad made of foamed urethane resin is attached to a polishing machine, after dressing is performed, dummy polishing is performed, after processing to remove the polishing residues that have built up in the polishing pad by the dummy polishing is then performed, an amount of polishing residues in the polishing pad is measured, and a rise of the polishing pad subjected to the dummy polishing is judged based on the measured amount of polishing residues. As a result, a method for raising a polishing pad can improve the particle level in the polishing pad life early stage.