CMP Polishing Pad Pore Control via Liquid Foaming
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Solution Overview
Problem
Existing polishing pads for semiconductor CMP processes face limitations in adjusting pore size and distribution, leading to suboptimal polishing rates and within-wafer non-uniformity.
Innovation Solution
A polishing pad with a polishing layer comprising pores of specific size and distribution, characterized by a number average diameter of 16 μm to less than 30 μm and an Ed value greater than 0, achieved by mixing a urethane-based prepolymer, a curing agent, and a solid phase foaming agent under reduced pressure, optimizing pore formation and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermally expanded microcapsules are used as a solid phase foaming agent, then the pore diameter can be uniformly controlled, but it is difficult to control the pores when the microcapsule shape changes under high temperature reaction conditions of 100°C or higher
Solution Approach 1:
The patent changes the physical state parameter of the foaming agent from solid microcapsules to liquid phase, which eliminates the shape change problem under high temperature conditions. The liquid phase foaming agent maintains its properties throughout the reaction process, ensuring reliable pore control while achieving uniform pore diameter through controlled injection and distribution mechanisms.
Solution Approach 2:
The patent replaces the mechanical/thermal expansion mechanism of solid microcapsules with a chemical reaction mechanism using liquid phase foaming agents. This substitution eliminates the dependency on thermal expansion and shape changes, providing more stable and controllable pore formation under high temperature reaction conditions.
2Volume of stationary object
If existing methods using inert gas and pore inducing polymer are used, then low-density polishing pad can be produced, but the size and distribution of pores cannot be adjusted
Solution Approach 1:
The patent applies local quality by controlling the distribution and concentration of liquid phase foaming agent in different regions of the polishing pad. By adjusting the injection amount, injection speed, and distribution pattern of the foaming agent, different pore sizes and densities can be created in different areas, enabling both low-density structure and precise pore control.
Solution Approach 2:
The patent introduces dynamic control mechanisms for pore formation by adjusting injection parameters (amount, speed, timing) of the liquid phase foaming agent. This dynamic approach allows real-time adjustment of pore size and distribution during the manufacturing process, overcoming the static limitations of existing methods.
3Ease of manufacture
If two kinds of solid phase foaming agents with different particle diameters are used, then polishing pad can be produced, but the polishing performance cannot be enhanced by adjusting pore size and distribution
Solution Approach 1:
The patent changes from using multiple solid phase foaming agents with different particle diameters to a single liquid phase foaming agent system with controllable injection parameters. This parameter-based control (injection amount, speed, timing) provides more precise and flexible adjustment of pore characteristics, enabling optimization of polishing performance while maintaining ease of manufacture.
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
Enhances polishing rate and within-wafer non-uniformity, enabling the efficient fabrication of high-quality semiconductor devices.
Implementation Method 1
or by generating a gas by a chemical reaction
Implementation Method 2
a liquid phase foaming agent filled with a volatile liquid
Implementation Method 3
an inert gas
Data Source
AI summary
Embodiments relate to a polishing pad for use in a chemical mechanical planarization (CMP) process of semiconductors, a process for preparing the same, and a process for preparing a semiconductor device using the same. In the polishing pad according to the embodiments, the number average diameter (Da) and number median diameter (Dm) of a plurality of pores are adjusted to achieve a specific range of the Ed value (Equation 1). As a result, an excellent polishing rate and within-wafer non-uniformity can be achieved.