Polishing Apparatus Press Pad for Bevel Portion
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Solution Overview
Problem
Conventional polishing apparatuses struggle to effectively polish the central region of a semiconductor wafer's bevel portion due to uneven pressure distribution, leading to excessive polishing at boundaries and instability in the polishing process.
Innovation Solution
A polishing apparatus featuring a press pad with a hard member secured only at its central portion, utilizing an elastic member to press the hard member against the bevel portion, allowing for controlled contact area and pressure distribution, thereby ensuring effective polishing of the central region without over-polishing the boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a conventional press pad with a rectangular pressing surface is used to press the polishing tape against the bevel portion, then the contact area between the polishing tape and the wafer is increased, but the polishing pressure becomes uneven with high pressure at boundaries and low pressure at the central region
Solution Approach 1:
The press pad is divided into two functional parts: a hard member (pressing section) that maintains pressure distribution and an elastic member (pad body) that provides flexibility. This segmentation allows the hard member to prevent excessive polishing at boundaries while the elastic member ensures adequate contact area, resolving the pressure distribution issue.
Solution Approach 2:
The hard member is designed with specific local properties (rigidity) at the pressing surface to control pressure distribution, while the elastic member provides different local properties (flexibility) at the pad body. This local quality differentiation enables the press pad to simultaneously achieve uniform pressure distribution and adequate contact area.
2Manufacturing precision
If polishing is performed to completely remove film or organic substance on the central region, then the central region is adequately polished, but the boundaries are excessively polished
Solution Approach 1:
By segmenting the press pad into hard and elastic members, the system achieves uniform pressure distribution across the bevel portion, allowing complete removal of film from the central region without excessive polishing at boundaries, thus improving manufacturing precision without extending polishing time.
Solution Approach 2:
The invention changes the physical parameters of the press pad by using a hard member with specific rigidity properties, which fundamentally alters the pressure distribution pattern during polishing, enabling uniform material removal across different regions of the bevel portion.
3Stress or pressure
If a polishing tape with a thicker base member is used to increase polishing pressure on the central region, then the central region polishing is improved, but larger reels are required and tension of the polishing tape largely affects polishing stability
Solution Approach 1:
Instead of increasing the thickness of the entire polishing tape base member, the invention segments the pressure application function into a hard member with pressing sections. This localized approach increases pressure on the central region without requiring a thicker overall tape, thus avoiding larger reels and tension-related stability issues.
Solution Approach 2:
The hard member provides localized rigidity and pressure control at the pressing surface without requiring the entire polishing tape to have increased thickness. This local quality enhancement achieves the desired pressure distribution while maintaining the original tape dimensions and tension characteristics.
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 achieves high polishing pressure on the central region of the bevel portion, improving the polishing rate and maintaining stability by increasing the contact area and optimizing pressure distribution, resulting in more efficient and controlled polishing.
Implementation Method 1
a pad body made from an elastic material such as urethane rubber or silicon sponge
Implementation Method 2
a polishing apparatus using a polishing tape... configured to press a polishing surface of the polishing tape against the bevel portion of the substrate to thereby polish the bevel portion
Data Source
AI summary
A polishing apparatus includes a substrate holder configured to hold and rotate a substrate, a press pad configured to press a polishing tape having a polishing surface against a bevel portion of the substrate held by the substrate holder, and a feeding mechanism configured to cause the polishing tape to travel in its longitudinal direction. The press pad includes a hard member having a pressing surface for pressing the bevel portion of the substrate through the polishing tape, and at least one elastic member for pressing the hard member against the bevel portion of the substrate through the belt-shaped polishing tool.