CMP Pad Through-Hole Water Flow Control for Accurate Film Thickness
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Solution Overview
Problem
The polishing pad wears over time, causing the through-hole to decrease in volume, leading to pure water overflow and slurry entry, which affects film thickness measurement accuracy in chemical mechanical polishing processes.
Innovation Solution
A polishing apparatus with a flow-rate adjusting device that adjusts the pure water flow based on the polishing pad's height, using correlation data to maintain optimal flow rates and prevent overflow or slurry entry through the through-hole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the flow rate of pure water is increased to prevent slurry entry, then light passage is ensured, but pure water overflows onto the polishing surface and dilutes the slurry
Solution Approach 1:
The patent applies dynamics by making the pure water flow rate adjustable rather than fixed. The flow rate is dynamically changed based on the polishing pad height (thickness), allowing the system to adapt to wear conditions. As the pad wears and thickness decreases, the flow rate is reduced to prevent overflow, while maintaining sufficient flow to prevent slurry entry and ensure light passage.
Solution Approach 2:
The patent changes the parameter of pure water flow rate according to the polishing pad height. By establishing a correspondence relationship between pad height and flow rate, the system adjusts the flow rate parameter to match the current state of the polishing pad, preventing both overflow and slurry entry while maintaining optical clarity.
2Object-generated harmful factors
If the flow rate of pure water is decreased to prevent overflow, then polishing surface is protected, but slurry enters the through-hole and obstructs light passage
Solution Approach 1:
The system dynamically adjusts the pure water flow rate based on real-time or pre-determined polishing pad height conditions. Rather than using a fixed low flow rate that causes slurry entry, the flow rate is optimized for each pad thickness condition, ensuring sufficient flow to prevent slurry contamination while avoiding overflow.
Solution Approach 2:
The patent establishes a correspondence relationship between polishing pad height and pure water flow rate. By changing the flow rate parameter according to the pad's current thickness (which decreases with wear), the system maintains optimal conditions for both overflow prevention and light passage through the through-hole.
3Productivity
If the polishing pad is used repeatedly, then productivity is improved, but the through-hole volume decreases causing pure water overflow
Solution Approach 1:
The patent makes the pure water flow rate dynamic and adaptive to pad wear. As the polishing pad is used repeatedly and its thickness decreases, the system automatically reduces the flow rate to prevent overflow. This allows continuous use of the same pad without requiring replacement, maintaining productivity while preventing harmful overflow effects.
Solution Approach 2:
The system incorporates feedback from pad height measurements to adjust the pure water flow rate. By monitoring or detecting the pad's current thickness and using this information to control the flow rate, the system enables repeated pad usage while preventing overflow, thereby extending pad life and improving productivity.
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
Prevents pure water overflow and slurry entry, ensuring accurate film thickness measurement by maintaining the through-hole's fill level with the appropriate water flow rate.
Implementation Method 1
an optical film thickness measurement system configured to direct light to the substrate through the through-hole, receive reflected light from the substrate through the through-hole, and determine a film thickness of the substrate based on the reflected light
Implementation Method 2
a flow-rate adjusting device coupled to the pure-water supply line; and an operation controller configured to control an operation of the flow-rate adjusting device
Data Source
AI summary
The present invention relates to a polishing apparatus and a polishing method for polishing a substrate while detecting a film thickness of the substrate by analyzing reflected light from the substrate on a polishing pad. The polishing apparatus includes a polishing table (3) configured to support a polishing pad (2) having a through-hole (61); a pad-height measuring device (32) configured to measure a height of the polishing surface (2a); a pure-water supply line (63) and a pure-water suction line(64) coupled to the through-hole (61) ; a flow-rate adjusting device (71) coupled to the pure-water supply line (63); and an operation controller (35) configured to control an operation of the flow-rate adjusting device (71). The operation controller (35) determines a flow rate of the pure water corresponding to a measured value of the height of the polishing surface (2a) from correlation data, and controls the operation of the flow-rate adjusting device (71) such that the pure water flows through the pure-water supply line (63) at the determined flow rate.