CMP Polishing Pad Surface Roughness Control via Micropore Design
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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 for curing, ensuring that the pad satisfies specific relationships in the areal material ratio curve after polishing, thereby controlling the surface roughness and improving the polishing performance.
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 changes the physical state parameter of the foaming agent from gas/liquid phase to solid phase, which enables precise control over pore formation parameters while maintaining the benefit of no harmful material discharge during CMP processing
Solution Approach 2:
The patent uses a composite structure where solid phase foaming agents are incorporated into the polishing pad matrix, creating a composite material that combines the advantages of controlled pore formation with the benefits of gas/liquid phase agents regarding material discharge
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
Solution Approach 1:
The patent adjusts the shape parameter of solid phase foaming agents from arbitrary shapes to spherical shapes, which prevents coalescence during mixing while maintaining precise control over pore formation characteristics
Solution Approach 2:
The patent applies different shape characteristics to different components: spherical shape for foaming agents to prevent coalescence, and controlled void structures within those spheres to achieve desired pore distribution and size in the final polishing pad
3Productivity
If the shape of micropores and pore coalescence phenomenon are not controlled, then the polishing rate, wafer planarization, and surface quality may be compromised, but controlling these parameters requires precise control of foaming agent shape and distribution which is difficult to achieve
Solution Approach 1:
The patent changes the shape parameter of foaming agents to spherical forms and controls their size distribution, which directly influences micropore formation characteristics and prevents coalescence, thereby optimizing polishing rate and surface quality
Solution Approach 2:
The patent establishes control mechanisms that monitor and adjust foaming agent distribution and pore formation characteristics to maintain optimal polishing performance, creating a feedback loop between manufacturing parameters and CMP process outcomes
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 controlled surface roughness characteristics of the polishing pad enhance the polishing rate, reduce residues and scratches, and minimize chatter marks on the wafer surface, leading to improved semiconductor device fabrication.
Implementation Method 1
or by generating a gas by a chemical reaction
Implementation Method 2
to thereby mechanically planarize the irregularities on the semiconductor substrate
Implementation Method 3
the wafer is then chemically treated by supplying a slurry while the platen and the head are relatively moved
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.