Polishing Pad Elemental Composition for CMP Rate and Bonding

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Solution Overview

Problem

The chemical mechanical planarization (CMP) process for semiconductors faces challenges in optimizing polishing rate due to variations in the physical properties of polishing pads, particularly the bonding strength between the polishing pad and substrate, which is influenced by the content of elements like oxygen, nitrogen, and carbon in the polishing layer.

Innovation Solution

A polishing pad with a specific composition of urethane-based prepolymer, curing agent, and foaming agent is developed, where the oxygen content is between 15% to 19% and the total nitrogen and oxygen content is between 20% to 27% by weight, or the nitrogen content is 7% or more, along with carbon and hydrogen, to enhance bonding strength and polishing rate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the composition of the polishing layer is adjusted to optimize polishing rate, then the polishing rate is improved, but the physical properties such as hardness and bonding strength may vary unpredictably

Engineering Contradiction:

Improvepolishing rateVSAvoidbonding strength between polishing pad and substrate

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling the elemental composition of the polishing layer. Specifically, it sets the oxygen content to 15-19 wt%, nitrogen content to 6-10 wt%, and carbon content to 70-78 wt%. This systematic adjustment of compositional parameters optimizes both the polishing rate and bonding strength, resolving the contradiction between productivity and reliability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material principles by creating a polishing layer with a specific multi-element composition (C, N, O, H) based on urethane-based prepolymer. This composite structure, formed by reacting diisocyanate compound and polyol with specific ratios, achieves synergistic effects that simultaneously improve polishing rate and bonding strength, rather than using a single material.

Inventive Principle:

Principle #40Composite materials

2Strength

If the content of oxygen and nitrogen elements is increased to improve bonding strength, then the bonding strength is improved, but the polishing rate may be reduced

Engineering Contradiction:

Improvebonding strength between polishing pad and substrateVSAvoidpolishing rate

Core Design Contradiction:

StrengthVSProductivity

Solution Approach 1:

The patent resolves this contradiction through precise parameter optimization. It establishes that oxygen content should be 15-19 wt% and nitrogen content 6-10 wt%, finding the optimal balance point where bonding strength is maximized without compromising polishing rate. This quantitative parameter control allows simultaneous achievement of both high strength and high productivity.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If the physical properties of the polishing layer are adjusted to enhance polishing performance, then the polishing rate is improved, but the manufacturing complexity increases

Engineering Contradiction:

Improvepolishing rateVSAvoidcomplexity of polishing pad composition control

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent simplifies the complexity by establishing clear, quantifiable parameter ranges for elemental composition. By specifying oxygen at 15-19 wt%, nitrogen at 6-10 wt%, and carbon at 70-78 wt%, it provides straightforward manufacturing guidelines that are easy to control and verify, reducing the practical complexity despite the sophisticated composition requirements.

Inventive Principle:

Principle #35Parameter changes

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 composition adjustment significantly improves the polishing rate and physical properties of the polishing pad, such as hardness and tensile strength, leading to enhanced CMP performance and the production of high-quality semiconductor devices.

Implementation Method 1

a urethane-based prepolymer obtained by reacting a diisocyanate compound and a polyol

Methodology Applied

Scientific EffectPolymerization: Chemical Bonding

Implementation Method 2

a foaming agent, and the like

Methodology Applied

Scientific EffectFoaming: Foam

Data Source

PatentUS11400559B2Polishing pad, process for preparing the same, and process for preparing a semiconductor device using the same

Publication Date: 2022.08.02 SK ENPULSE CO LTD

AI summary

The polishing pad according to an embodiment adjusts the content of elements present in the polishing layer, thereby controlling the bonding strength between the polishing pad and the polishing particles and enhancing the bonding strength between the polishing particles and the semiconductor substrate (or wafer), resulting in an increase in the polishing rate. It is possible to enhance not only the mechanical properties of the polishing pad such as hardness, tensile strength, elongation, and modulus, but also the polishing rate for both a tungsten layer or an oxide layer. Accordingly, it is possible to efficiently fabricate a semiconductor device of excellent quality using the polishing pad.