Polishing Pad Light-Transmitting Region Segmentation
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Solution Overview
Problem
Current polishing pads used in chemical mechanical polishing (CMP) face challenges in preventing slurry leakage and maintaining high optical detection accuracy, leading to inefficiencies in detecting the endpoint of polishing and achieving desired surface properties on semiconductor wafers.
Innovation Solution
A polishing pad structure featuring a light-transmitting region with a recessed part on the polishing platen-side surface, where the support film is only layered on the peripheral part, preventing slurry leakage and maintaining high light transmittance for improved optical detection accuracy by allowing the optical detection device to be closer to the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a support film is layered across the entire light-transmitting region to prevent slurry leakage, then slurry leakage is prevented, but light transmittance is reduced and optical detection accuracy deteriorates
Solution Approach 1:
The light-transmitting region is divided into two functional zones: a peripheral part where the support film is layered to prevent slurry leakage, and a central recessed part where the support film is removed to maintain high light transmittance. This segmentation allows simultaneous achievement of slurry containment and optical detection accuracy.
Solution Approach 2:
Different regions of the light-transmitting region are assigned different properties: the peripheral part has support film coverage for mechanical stability and slurry prevention, while the central recessed part has no support film for optimal light transmission. This local differentiation resolves the contradiction between leakage prevention and optical performance.
2Measurement precision
If the optical detection device is positioned closer to the wafer for better detection accuracy, then measurement precision improves, but slurry leakage risk increases
Solution Approach 1:
The support film coverage is segmented to provide containment at the periphery while leaving the central detection area open, enabling the optical device to be positioned close to the wafer without compromising slurry containment integrity.
3Loss of information
If periodic test wafer treatment is conducted to monitor polishing progress, then polishing state can be assessed, but processing time and cost increase
Solution Approach 1:
The patent implements real-time feedback through in-situ optical detection during CMP processing. The optical detection device continuously monitors the wafer surface through the light-transmitting region, providing immediate feedback on polishing progress and enabling endpoint detection without removing the wafer for separate testing.
Solution Approach 2:
The polishing system performs self-monitoring through integrated optical detection, eliminating the need for separate test wafer processing. The system detects its own polishing state in real-time, converting the monitoring function from an external quality control step to an inherent process feature.
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 effectively prevents slurry leakage and enhances optical detection accuracy by ensuring that the support film does not obstruct light transmittance, allowing for precise endpoint detection during CMP processes.
Implementation Method 1
detecting the end-point of polishing by irradiating a wafer via a polishing pad through a window (light-transmitting region) with light beam, and monitoring interference signal generated by reflection of the light beam
Implementation Method 2
monitoring interference signal generated by reflection of the light beam
Implementation Method 3
monitoring interference signal generated by reflection of the light beam
Data Source
AI summary
An object of the invention is to provide a polishing pad that is prevented from slurry leaks and has high optical detection accuracy. The present invention relates to a polishing pad comprising a polishing region, a cushion layer, and a support film layered in this order, wherein a light-transmitting region is provided on the support film and in an opening part that passes through the polishing region and the cushion layer; the light-transmitting region has a peripheral part and a recessed part on the surface of a polishing platen-side; the support film is layered on the peripheral part; and the support film is not layered on the recessed part, which remains open.