Elastic Membrane Substrate Holder for Wafer Polishing
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Solution Overview
Problem
Conventional polishing apparatuses face challenges in maintaining uniform polishing performance due to non-uniform temperature distribution and pressure control during semiconductor wafer polishing, leading to suboptimal planarization and productivity issues.
Innovation Solution
A substrate holding apparatus with an elastic membrane and an infrared light detector measures thermal energy from the membrane to estimate the substrate's temperature, allowing for precise temperature control and pressure adjustment to maintain uniform polishing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the relative pressing force applied between the semiconductor wafer and the polishing surface is not uniform, then the surface of the semiconductor wafer is polished insufficiently or excessively in different regions, but providing a pressure chamber with fluid pressure complicates the device structure
Solution Approach 1:
The patent changes the physical state of the membrane from rigid to elastic, allowing it to deform and distribute pressure uniformly across the wafer surface. This elastic deformation enables uniform pressing force without requiring complex pressure control systems with multiple chambers and fluid supply mechanisms.
Solution Approach 2:
The elastic membrane automatically adjusts and distributes pressure uniformly across the wafer surface through its inherent elastic properties. The membrane self-regulates the pressure distribution without requiring external control systems, eliminating the need for complex pressure chambers and fluid supply mechanisms.
2Manufacturing precision
If the entire surface of the semiconductor wafer is pressed uniformly, then the initial film thickness distribution cannot be corrected, but applying non-uniform pressure requires multiple pressure chambers with independent control
Solution Approach 1:
The patent changes the membrane from rigid to elastic, enabling it to adapt its pressure distribution automatically. The elastic membrane can create non-uniform pressure patterns that correct film thickness variations without requiring multiple independently controlled pressure chambers.
Solution Approach 2:
The elastic membrane provides dynamic pressure adjustment capabilities, allowing the pressure distribution to change in response to wafer characteristics. This dynamic adaptation enables correction of film thickness non-uniformity without the complexity of multiple controlled pressure chambers.
3Productivity
If the polishing temperature is not controlled, then the polishing rate distribution changes and productivity decreases, but measuring and controlling temperature adds device complexity
Solution Approach 1:
The patent replaces complex temperature measurement and control mechanisms with a simpler approach using the elastic membrane's mechanical properties. The membrane's elasticity and response to temperature changes provide indirect temperature monitoring and control without requiring direct temperature sensors or complex thermal management systems.
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 enables accurate temperature estimation and control, improving planarization, productivity, and maintaining consistent polishing pressure, thereby enhancing the overall polishing performance and stability.
Implementation Method 1
an infrared light detector configured to measure thermal energy from the elastic membrane
Data Source
AI summary
A polishing is used for polishing a substrate such as a semiconductor wafer to a flat mirror finish. The polishing apparatus includes a polishing table having a polishing surface, a substrate holding apparatus configured to hold the substrate and to press the substrate against the polishing surface, and a controller. The substrate holding apparatus includes an elastic membrane configured to forma substrate holding surface which is brought into contact with the substrate, a carrier provided above the elastic membrane, at least one pressure chamber formed between the elastic membrane and the carrier, and an infrared light detector configured to measure thermal energy from the elastic membrane. The controller calculates an estimate value of a temperature of the elastic membrane using a measured value of the infrared light detector.