CMP Polishing Pad Surface Roughness via Solid-Phase 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 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:
A solid phase foaming agent is introduced as an intermediary substance to create micropores with controlled characteristics. The solid phase foaming agent acts as a mediator that enables precise pore formation while maintaining shape stability during CMP, resolving the contradiction between avoiding harmful material discharge and achieving precise pore control
Solution Approach 2:
The invention changes the physical state parameter of the foaming agent from gas/liquid phase to solid phase. This parameter change enables the foaming agent to maintain its shape and provide controlled pore formation, thereby achieving precise control over pore size, distribution, and number while maintaining pore shape during the CMP process
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 solid phase foaming agent is pre-formed with a specific structure including an outer wall and void before being mixed into the polishing pad composition. This preliminary preparation of the foaming agent structure enables precise pore control while preventing coalescence during the mixing process, as the pre-formed outer wall maintains integrity throughout manufacturing
3Productivity
If the shape of micropores and pore coalescence phenomenon are not controlled, then the polishing rate, wafer planarization, and surface quality may be affected, but controlling these parameters requires precise control of the foaming agent which complicates the manufacturing process
Solution Approach 1:
By changing the foaming agent to solid phase, the invention achieves precise control over pore parameters (size, distribution, number, and shape) without significantly complicating the manufacturing process. The solid phase nature of the agent provides inherent control mechanisms that simplify the overall manufacturing complexity while improving 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
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, resulting in improved CMP process performance.
Implementation Method 1
by generating a gas by a chemical reaction
Implementation Method 2
the wafer is then chemically treated by supplying a slurry while the platen and the head are relatively moved, to thereby mechanically planarize the irregularities on the semiconductor substrate
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.