CMP Polishing Pad Surface Roughness for Stable Micropores
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Solution Overview
Problem
The existing methods for preparing polishing pads in the CMP process face challenges in controlling the shape and coalescence of micropores, which affect the surface roughness characteristics, leading to issues with residues, scratches, and chatter marks on the wafer surface, and hinder the optimization of the polishing rate.
Innovation Solution
A polishing pad is developed by mixing a urethane-based prepolymer, a curing agent, and a foaming agent, and then injecting the mixture into a mold to form a polishing layer, ensuring that the surface roughness characteristics meet specific criteria in the areal material ratio curve based on the ISO 25178-2 standard, thereby controlling the shape and coalescence of micropores.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a gas phase or liquid phase foaming agent is used to form micropores, then no material that may affect the CMP process is discharged, but it is difficult to precisely control the size, size distribution, and number of pores, and the shape of micropores cannot be maintained during the CMP process
Solution Approach 1:
The patent uses a solid phase foaming agent as an intermediary substance that provides both the foaming function and the structural support needed to maintain pore shape. The solid phase foaming agent acts as a mediator between the requirement for no harmful material discharge and the need for precise pore control, as it decomposes to release gas while maintaining pore structure during the CMP process.
Solution Approach 2:
The polishing pad employs a composite structure combining polyurethane resin with solid phase foaming agent particles. This composite material approach allows the foam structure to be maintained during CMP, achieving both the benefit of no harmful discharge and precise pore control through the combined properties of the resin matrix and foaming agent particles.
2Manufacturing precision
If a solid phase foaming agent having an outer wall and a void is used, then the shape, size distribution, and number of pores can be precisely controlled and the shape of micropores can be maintained during the CMP process, but it is difficult to freely control the shape of the solid phase foaming agent and the agent may partially coalesce in the polishing pad during mixing
Solution Approach 1:
The patent optimizes parameters including the particle size distribution, wall thickness ratio, and void ratio of the solid phase foaming agent to prevent coalescence during mixing. By carefully controlling these parameters, the foaming agent maintains its shape and distribution throughout the polishing pad manufacturing process while achieving precise pore control.
Solution Approach 2:
The solid phase foaming agent is pre-formed with a specific outer wall structure and void configuration before being incorporated into the polishing pad. This preliminary preparation ensures that the foaming agent maintains its shape during subsequent mixing and curing processes, preventing coalescence while enabling precise pore control.
3Productivity
If the shape and coalescence phenomenon of micropores are not controlled, then the polishing rate, wafer planarization, and surface quality are adversely affected, but precise control requires complex manufacturing processes
Solution Approach 1:
The patent extracts the pore-forming function into a separate solid phase foaming agent component that can be independently controlled and optimized. This separation allows the polishing pad matrix to focus on providing mechanical support while the foaming agent specifically controls pore formation, simplifying the overall manufacturing process while achieving precise control over polishing performance.
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 effectively adjusts the surface roughness of the polishing pad, improving the polishing rate and reducing residues, scratches, and chatter marks on the wafer surface, while maintaining consistent performance throughout the CMP process.
Implementation Method 1
the method of using a gas phase or liquid phase foaming agent to form micropores
Implementation Method 2
by generating a gas by a chemical reaction
Implementation Method 3
the presence of the outer wall of the solid phase foaming agent
Implementation Method 4
when the polishing pad after the polishing is measured with an optical surface roughness meter
Data Source
AI summary
The embodiments relate to a polishing pad for use in a chemical mechanical planarization (CMP) process of semiconductors, to a process for preparing the same, and to a process for preparing a semiconductor device using the same. The polishing pad according to the embodiment adjusts the surface roughness characteristics of the polishing pad after polishing, whereby the polishing rate can be enhanced, and the surface residues, surface scratches, and chatter marks of the wafer can be remarkably reduced.