Polishing Pad Curing Agent Mixture for Thermal Stability
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Solution Overview
Problem
The existing chemical mechanical planarization (CMP) process for semiconductors faces challenges with polishing rate and surface defects due to the thermal instability of polishing pads, particularly at high temperatures, and the use of harmful substances like 4,4′-methylenebis(2-chloroaniline) (MOCA), which affects both the environment and human health.
Innovation Solution
A composition comprising a urethane-based prepolymer and a mixture of curing agents, including a sulfur-containing first curing agent and an ester-group containing second curing agent, is used to enhance the polishing pad's thermal stability and reduce surface defects, without relying on MOCA, by adjusting the content ratio of these agents to optimize physical properties and elongation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MOCA is used as a curing agent to enhance polishing rate and physical properties, then polishing rate and physical properties are improved, but thermal stability deteriorates at high temperatures and long operation periods
Solution Approach 1:
The patent changes the chemical composition parameters by replacing MOCA with a mixture of alternative curing agents (curing agent A and curing agent B) in specific ratios. This parameter change maintains the polishing rate while improving thermal stability, as the new curing agent mixture does not exhibit the thermal degradation issues of MOCA at high temperatures
Solution Approach 2:
The patent uses a composite curing agent system combining curing agent A and curing agent B in a specific ratio (0.3:0.7 to 0.7:0.3). This composite approach leverages the complementary properties of each curing agent to achieve both high polishing rate and improved thermal stability, resolving the contradiction between productivity and thermal stability
2Strength
If high-hardness additive is used in the polishing layer to improve physical properties, then hardness is improved, but scratches and surface defects increase on the semiconductor substrate
Solution Approach 1:
The patent changes the hardness parameter by selecting specific types and amounts of high-hardness additives (such as alumina or silica particles with controlled size distributions). By optimizing these parameters, the polishing layer achieves sufficient hardness for effective polishing while minimizing the generation of scratches and surface defects on the semiconductor substrate
3Productivity
If polishing is carried out at high temperature (50°C or higher) to improve processing efficiency, then polishing speed is improved, but thermal stability of the polishing pad deteriorates and polishing rate decreases over time
Solution Approach 1:
The patent changes the thermal parameter by modifying the curing agent composition to be thermally stable. The mixture of curing agent A and curing agent B maintains the structural integrity of the polishing pad at high temperatures (50°C or higher), preventing the degradation and hardening that would otherwise reduce polishing stability and rate over time
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 provides a polishing pad with improved thermal stability, reduced surface defects, and enhanced polishing rate, maintaining stability over long periods at high temperatures while being environmentally friendly by minimizing the use of harmful substances.
Implementation Method 1
A composition comprising a urethane-based prepolymer and a mixture of curing agents, wherein the mixture of curing agents comprises a first curing agent containing sulfur and a second curing agent containing an ester group
Implementation Method 2
The pores in a polishing layer may be formed by using a solid phase foaming agent having a fine hollow structure, a liquid phase foaming agent using a volatile liquid, a gas phase foaming agent such as an inert gas, or the like, or by generating a gas by a chemical reaction
Data Source
AI summary
The composition according to an embodiment employs a mixture of curing agents, which comprises a first curing agent containing sulfur and a second curing agent containing an ester group, whereby it is possible to control the physical properties of the polishing pad as necessary.