Polishing Pad Dressing Control for Cut Rate Consistency
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Solution Overview
Problem
Existing substrate polishing methods face challenges in maintaining a consistent polishing rate due to variations in the cut rate of the polishing pad, which can be affected by individual differences in the pad, water absorption, environmental factors, and wear over time.
Innovation Solution
A substrate polishing method that involves performing multiple dressings under preset conditions, measuring and storing the corresponding cut rates, and adjusting the dress conditions in real-time to maintain a target cut rate, thereby stabilizing the polishing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the moving speed of the dresser is increased at a radial position on the polishing pad, then the cut rate control is improved, but it becomes difficult to maintain the target cut rate consistently across different positions
Solution Approach 1:
The polishing pad surface is divided into multiple measurement regions (first region and second region) with different target cut rates. The dresser control device independently controls the dressing amount in each region based on measured heights, allowing localized optimization of cut rate consistency across different positions of the polishing pad.
Solution Approach 2:
Different target cut rates are set for different regions of the polishing pad. The first region has a first target cut rate and the second region has a second target cut rate, allowing each region to be optimized for its specific requirements rather than applying a uniform standard across the entire pad surface.
2Ease of operation
If the same dress condition is applied to all polishing pads, then the process is simplified, but variations in individual pad differences, water absorption, and environment cause cut rate variations
Solution Approach 1:
The system performs self-adjustment by automatically measuring the actual height of the polishing pad surface and comparing it with target heights. The dresser control device then automatically adjusts dressing conditions based on measured deviations, enabling the system to compensate for individual pad differences, water absorption variations, and environmental factors without manual intervention.
Solution Approach 2:
The height measurement device continuously monitors the polishing pad surface height, and the dresser control device uses this feedback information to adjust dressing conditions in real-time. This closed-loop control ensures consistent cut rates despite variations in pad individuality, water absorption, and environmental conditions.
3Productivity
If the dresser moves faster to maintain throughput, then productivity is improved, but the cut rate control becomes less precise
Solution Approach 1:
The height measurement and dresser control operations are performed continuously during the polishing process without interrupting substrate polishing. The dresser can operate at high speeds while maintaining precise cut rate control through continuous measurement and real-time adjustment, ensuring both productivity and measurement precision are maintained.
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 method allows for precise control of the polishing process, ensuring consistent cut rates and maintaining high polishing efficiency by adapting to changes in the polishing pad over time.
Implementation Method 1
a pad height sensor 32 for measuring the height of a polishing pad surface 11a
Implementation Method 2
the surface of the polishing member is subjected to dressing (setting) with a dresser in which a large number of abrasive grains such as diamond grains are electrodeposited
Implementation Method 3
chemical mechanical polishing (CMP) apparatus... the surface (surface to be polished) of the object to be polished is pressed against the surface of the polishing member, and the polishing member and the object to be polished are relatively moved while a polishing liquid (abrasive liquid, chemical liquid, slurry, pure water, or the like) is supplied
Data Source
AI summary
A first dressing of dressing a polishing member is performed under a plurality of preset set dress conditions, a first cut rate of the polishing member is measured based on a measurement value of a surface height of the polishing member for each set dress condition, and the set dress condition and the first cut rate are associated with each other and stored as relationship data. The substrate is polished by applying a first dress condition corresponding to a target cut rate based on the relationship data, and a second cut rate of the polishing member is measured based on the measurement value of the surface height of polishing member. A second dress condition corresponding to the target cut rate is acquired based on a change of the second cut rate from the target cut rate and the relationship data, and substrate is polished by applying the second dress condition.