CMP Dresser Height Measurement and Slurry Removal
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Solution Overview
Problem
The replacement of dressers in Chemical Mechanical Polishing (CMP) processes leads to variations in cutting rate and polishing profile due to individual dresser properties, affecting the initial polishing performance and causing slurry deposition on the dresser, which destabilizes the polishing process.
Innovation Solution
A method and apparatus that measure and maintain a constant cutting rate of the polishing pad by repetitively moving the dresser across the pad, measuring the pad's height in multiple zones, and adjusting the dressing conditions based on these measurements to prevent variations and slurry deposition, using a dresser-preconditioning device to prepare new dressers without affecting the polishing pad.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a new dresser is replaced in the CMP apparatus, then the polishing surface can be restored, but variations in cutting rate and polishing profile occur due to individual dresser properties
Solution Approach 1:
The patent applies parameter changes by adjusting the dresser pressing force and dressing conditions to compensate for variations in individual dresser properties. By measuring the actual cutting rate and polishing profile, the system dynamically modifies dressing parameters to maintain consistent polishing performance across different dressers.
Solution Approach 2:
The patent implements feedback control by measuring the polishing profile and cutting rate after dresser replacement, then using this information to adjust subsequent dressing operations. This closed-loop approach ensures that variations in individual dresser properties do not affect overall polishing consistency.
2Ease of manufacture
If preconditioning is performed on a new dresser by pressing it against the polishing pad, then the dresser is prepared for use, but polishing performance is adversely affected at the initial stage
Solution Approach 1:
The patent applies preliminary action by performing light dressing operations on the new dresser before actual polishing begins. This preliminary conditioning removes excessive material and prepares the dresser surface without applying enough pressure to cause the harmful effects associated with traditional preconditioning, thus maintaining initial polishing performance.
3Manufacturing precision
If the dresser is pressed against the polishing pad during dressing, then the polishing surface is planarized, but slurry is deposited firmly on the dresser
Solution Approach 1:
The patent applies the extraction principle by removing slurry from the dresser surface through cleaning operations between dressing cycles. This prevents slurry accumulation that would otherwise interfere with subsequent dressing operations and maintain polishing surface quality.
Solution Approach 2:
The patent implements periodic action by performing intermittent cleaning of the dresser surface during the dressing process. Rather than continuous contact that would cause slurry buildup, the system periodically removes slurry to maintain dresser effectiveness and prevent harmful deposition.
4Adaptability or versatility
If individual dressers with different properties are used, then dresser replacement is possible, but removal rate and polishing profile vary
Solution Approach 1:
The patent applies dynamics by making the dressing process adaptive rather than static. The system dynamically adjusts dressing parameters based on real-time measurements of cutting rate and polishing profile, allowing consistent performance regardless of which specific dresser is in use. This dynamic adjustment compensates for individual dresser property variations.
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 ensures consistent polishing performance by maintaining a constant cutting rate and preventing slurry deposition, thereby improving the accuracy and stability of the polishing process and extending the service life of the dresser.
Implementation Method 1
a dresser 108 for restoring the polishing surface of the polishing pad 100 that has been deteriorated through the polishing process. The dresser 108 is configured to rotate about its own axis and bring a dressing surface thereof into contact with the polishing surface of the polishing pad 100 on the rotating polishing table 102 to thereby remove the polishing liquid and debris on the polishing surface and also planarize and dress the polishing surface of the polishing pad 100. Typically, a diamond dresser is used as the dresser 108 for scraping and planarizing the polishing surface of the polishing pad 100.
Data Source
AI summary
A dressing method is used to dress a polishing pad of a polishing apparatus for polishing a substrate. This method includes repetitively moving the dresser on an upper surface of the polishing pad in a radial direction of the polishing pad so as to perform a dressing process on the polishing pad, during the dressing process, measuring a height of an upper surface of the polishing pad at a predetermined point in one of plural zones on the polishing surface, and repeating the repetitive moving of the dresser and the measuring of the height of the upper surface of the polishing pad so as to measure the height of the upper surface of the polishing pad in all of the plural zones.