Polishing Pad Temperature Control via Gas Ejection Nozzles
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Solution Overview
Problem
In chemical mechanical polishing (CMP) processes for semiconductor wafers, the step height characteristics and polishing rate are adversely affected by temperature variations of the polishing pad, leading to issues like dishing and erosion, and the scattering of polishing liquid, which causes scratches and reduces efficiency.
Innovation Solution
A polishing apparatus with integrated gas ejection nozzles to control the temperature of the polishing pad and an atomizer to remove foreign matter, where the gas ejection nozzles are inclined to enhance cooling capacity and reduce slurry scattering, and the atomizer uses a mixed fluid to improve detergency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If gas ejection nozzles are added to control polishing pad temperature, then temperature control and polishing rate optimization are improved, but device complexity increases
Solution Approach 1:
The gas ejection nozzle system is designed to serve multiple functions: cooling the polishing pad to control temperature, reducing slurry scattering through gas flow, and potentially assisting in debris removal. This multi-functionality justifies the added complexity by addressing multiple problems with a single integrated system.
Solution Approach 2:
The invention employs gas ejection nozzles that utilize pneumatic principles to deliver controlled flows of gas (typically nitrogen or compressed air) onto the polishing pad surface. The pneumatic system enables precise temperature control through regulated gas flow rates and pressures, while also creating a gas barrier that reduces slurry scattering.
2Manufacturing precision
If gas ejection nozzles are used to control polishing pad temperature, then polishing rate and step height characteristics are improved, but polishing liquid scattering increases
Solution Approach 1:
The ejected gas acts as an intermediary medium between the polishing pad and the slurry. By introducing a gas flow field, the system creates a barrier that prevents slurry droplets from scattering onto surrounding surfaces while allowing the gas to simultaneously cool the polishing pad. This intermediary gas layer resolves the conflict between temperature control and scattering prevention.
Solution Approach 2:
The invention converts the potentially harmful effect of gas ejection (which could disturb slurry and cause scattering) into a beneficial effect by carefully controlling the gas flow parameters. The gas flow is optimized to cool the pad and prevent scattering without creating turbulence that would worsen the scattering problem.
3Temperature
If gas ejection nozzles are positioned to maximize cooling capacity, then temperature control is improved, but slurry scattering is worsened
Solution Approach 1:
The gas ejection nozzles are strategically positioned and angled to create localized gas flow zones that target specific areas of the polishing pad requiring cooling. The gas flow direction and intensity are optimized for each nozzle location to maximize cooling efficiency while minimizing disruption to slurry flow patterns in adjacent areas.
Solution Approach 2:
The gas ejection system incorporates adjustable flow rates and pressures that can be dynamically modified during the polishing process. This dynamic control allows the system to adapt gas flow conditions to match the actual temperature requirements and slurry flow patterns, optimizing both cooling performance and scattering prevention in real-time.
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
The solution maintains optimal polishing rates and step height characteristics by controlling the polishing pad temperature, reduces dishing and erosion, and minimizes scratches by effectively managing the polishing liquid flow, thereby improving productivity and reducing consumable costs.
Implementation Method 1
a surface (polishing surface) of a polishing pad is cooled by ejecting a gas from gas ejection nozzles toward the polishing pad
Implementation Method 2
there is a problem that mist of slurry supplied onto the polishing pad is scattered around
Data Source
AI summary
A polishing apparatus polishes a surface of a substrate by pressing the substrate against a polishing pad on a polishing table. The polishing apparatus is configured to control a temperature of the polishing surface of the polishing pad by blowing a gas on the polishing pad during polishing. The polishing apparatus includes a pad temperature control mechanism having at least one gas ejection nozzle for ejecting a gas toward the polishing pad and configured to blow the gas onto the polishing pad to control a temperature of the polishing pad, and an atomizer having at least one nozzle for ejecting a liquid or a mixed fluid of a gas and a liquid and configured to blow the liquid or the mixed fluid onto the polishing pad to remove foreign matters on the polishing pad. The pad temperature control mechanism and the atomizer are formed into an integral unit.