CMP Polishing Surface Temperature Control for Throughput Stability
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Solution Overview
Problem
The CMP apparatus faces instability in throughput due to varying polishing times for wafers with different initial film thicknesses, making it challenging to achieve consistent processing times across multiple wafers.
Innovation Solution
A polishing method and apparatus that regulate the temperature of the polishing surface using a heat exchanger to maintain a target polishing rate, ensuring that the film thickness of the substrate reaches the target thickness at a preset polishing time by adjusting the temperature based on a relational expression correlating polishing rate and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polishing time is determined by film thickness reaching target thickness, then polishing precision is improved, but throughput stability deteriorates due to varying initial film thickness
Solution Approach 1:
The patent changes the control parameter from film thickness-based termination to time-based termination with fixed polishing time. By controlling the polishing process duration rather than monitoring film thickness continuously, the system achieves stable throughput while maintaining precision through the fixed time parameter
Solution Approach 2:
The patent replaces the mechanical measurement system (film thickness monitoring) with a time-based control system. Instead of continuously measuring film thickness to determine polishing endpoint, the system uses a predetermined fixed time duration, substituting complex measurement with simple time control
2Manufacturing precision
If polishing time varies to accommodate different initial film thicknesses, then polishing precision is maintained, but productivity deteriorates due to unstable throughput
Solution Approach 1:
The patent changes the termination parameter from film thickness (variable) to fixed time (constant). This parameter transformation allows the system to process wafers with different initial film thicknesses in uniform time intervals, stabilizing throughput while maintaining precision through controlled polishing duration
Solution Approach 2:
The patent introduces dynamic temperature control during polishing to compensate for variations in initial film thickness. By adjusting polishing pad or wafer temperature in real-time, the system maintains consistent polishing rates across different wafers, enabling fixed time termination while preserving polishing precision
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 allows for consistent termination of polishing at a fixed time across multiple substrates, stabilizing throughput by maintaining the polishing rate at the target rate, thus ensuring that the film thickness reaches the target thickness simultaneously with the preset polishing time.
Implementation Method 1
regulating a temperature of the polishing surface by a heat exchanger
Data Source
AI summary
A polishing method capable of terminating polishing of a substrate, such as a wafer, at a preset polishing time is disclosed. The polishing method includes: polishing a substrate by pressing the substrate against a polishing surface of a polishing pad, while regulating a temperature of the polishing surface by a heat exchanger; calculating a target polishing rate required for an actual polishing time to coincide with a target polishing time, the actual polishing time being a time duration from start of polishing the substrate until a film thickness of the substrate reaches a target thickness; determining a target temperature of the polishing surface that can achieve the target polishing rate; and during polishing of the substrate, changing a temperature of the polishing surface to the target temperature by the heat exchanger.