Polishing Apparatus Standby Dressing and Top Ring Pressurization
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Solution Overview
Problem
The existing polishing methods for semiconductor wafers require the use of dummy wafers to restore the polishing pad's condition after idling, leading to increased costs and a larger footprint, as well as the degradation of the top ring's elastic components due to prolonged use, which affects the polishing efficiency.
Innovation Solution
Implementing a preparatory process during the stand-by operation that includes dressing the polishing surface and supplying a polishing liquid to bring the polishing pad to the optimal condition for polishing, without using dummy wafers, and pressurizing the top ring's pressure chambers to maintain the elastic body's functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dummy wafers are used to restore polishing pad condition after idling, then polishing pad temperature and slurry wetting are improved, but cost and equipment footprint increase
Solution Approach 1:
The patent applies preliminary action by performing dressing and slurry supply to the polishing pad during the stand-by operation, before actual polishing resumes. This pre-treatment restores the polishing pad surface roughness and temperature, and ensures proper slurry wetting, eliminating the need for dummy wafers that were traditionally used for this purpose.
Solution Approach 2:
The patent extracts and eliminates the dummy wafer from the polishing process. By separating the pad restoration function from the wafer polishing function, the invention allows the polishing pad to be prepared independently during stand-by time using dressing and slurry supply, removing the requirement for consumable dummy wafers.
2Force
If elastic bodies in top ring pressure chambers are used for substrate pressing, then substrate contact pressure is improved, but elastic body hardening occurs over time reducing effectiveness
Solution Approach 1:
The patent applies periodic action by supplying gas to the pressure chambers during stand-by operation to periodically expand and contract the elastic bodies. This cyclic pressurization prevents the elastic bodies from hardening by maintaining their flexibility through repeated deformation cycles, even when no substrate is being polished.
Solution Approach 2:
The elastic bodies perform self-maintenance through periodic gas pressurization during stand-by periods. The system automatically restores the elastic properties of the elastic bodies by subjecting them to controlled expansion and contraction, enabling them to maintain their pressing force capability without external intervention or replacement.
3Productivity
If polishing liquid is supplied during stand-by operation to maintain pad temperature, then polishing rate is improved, but liquid consumption increases
Solution Approach 1:
The patent applies partial action by supplying polishing liquid during stand-by operation only to the extent necessary for maintaining pad temperature and surface conditions, rather than continuous full polishing conditions. The dressing process uses minimal liquid to achieve the required surface roughness and temperature restoration.
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 eliminates the need for dummy wafers, reduces costs, extends the life of the polishing pad, and maintains the top ring's pressure expansion capabilities, thereby enhancing polishing efficiency and reducing waste.
Implementation Method 1
carrying out a preparatory process to polishing by dressing a polishing surface
Implementation Method 2
supplying a polishing liquid to the polishing surface
Implementation Method 3
The pressure chamber can be pressurized by supplying a gas into the chamber so as to expand and contract the elastic body
Implementation Method 4
pressurizing the top ring's pressure chambers
Implementation Method 5
polishing of substrates, such as semiconductor wafers
Data Source
AI summary
A polishing method can bring a polishing surface to the optimum condition for polishing, without using a dummy wafer, before resuming polishing, thereby eliminating the cost of dummy wafer. The polishing method includes carrying out a stand-by operation during a polishing-resting time period, carrying out a preparatory process to polishing, after completion of the stand-by operation, by dressing a polishing surface while supplying a polishing liquid to the polishing surface, and starting polishing of a workpiece after completion of the preparatory process to polishing. A determination as to whether to carry out the preparatory process to polishing after completion of the stand-by operation may be made based on the total operating time of the stand-by operation or the total effective number of the stand-by operations.