Polyurethane-Polyurea Polishing Pad for Scratch Reduction
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Solution Overview
Problem
Conventional hard (dry) polishing pads for semiconductor devices cause scratches and have a high likelihood of clogging, while soft (wet) polishing pads provide better polishing rate and uniformity but fail to maintain a consistent polishing state due to anisotropic cell shapes and low-density portions being torn off.
Innovation Solution
A polishing pad with a polyurethane-polyurea resin foam having a specific range of spin-spin relaxation times, storage elastic modulus, density, and cell diameter, manufactured using a method involving isocyanate and polyamine compounds, which results in a polishing layer with moderate dressing properties and reduced scratch formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard (dry) polishing pad with high density and high storage elastic modulus is used, then rigidity for keeping flatness is improved, but scratch occurrence increases and dressing properties deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the storage elastic modulus within 1-30 MPa and density within 0.30-0.60 g/cm³, along with specific spin-spin relaxation time T2M of 160-260 μs. These parameter optimizations balance the rigidity needed for flatness maintenance with the softness required to reduce scratches and improve dressing properties
Solution Approach 2:
The patent uses a composite polyurethane-polyurea resin foam structure that combines the rigidity benefits of hard materials with the elasticity and scratch-reduction benefits of softer materials, achieving a balanced performance profile that neither pure hard nor pure soft materials can provide
2Object-affected harmful factors
If a soft (wet) polishing pad with low density and low storage elastic modulus is used, then scratch occurrence is reduced, but polishing state consistency deteriorates due to anisotropic cell shapes and low-density portions being torn off
Solution Approach 1:
The patent optimizes parameters including storage elastic modulus (1-30 MPa), density (0.30-0.60 g/cm³), and spin-spin relaxation time (T2M: 160-260 μs) to achieve a balance between softness for scratch reduction and structural integrity for consistent polishing performance throughout the pad's service life
Solution Approach 2:
The patent creates uniform isotropic cell structures throughout the polishing pad with consistent density distribution, ensuring that all regions maintain similar mechanical properties and wear characteristics, preventing localized failure and maintaining consistent polishing state
3Strength
If a hard polishing pad with high density is used, then rigidity is improved, but dressing properties worsen due to excessive hardness
Solution Approach 1:
The patent precisely controls the storage elastic modulus within 1-30 MPa and density within 0.30-0.60 g/cm³, along with spin-spin relaxation time T2M of 160-260 μs, to achieve optimal dressing properties while maintaining sufficient rigidity for flatness control during polishing
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 polishing pad achieves excellent polishing rate and uniformity while reducing scratch occurrence and maintaining a consistent polishing state for a longer period, suitable for both primary and finish processing.
Implementation Method 1
the storage elastic modulus E' of 1 to 30 MPa, the storage elastic modulus E' being measured at 40°C with an initial load of 10 g, a strain range of 0.01 to 4%, and a measuring frequency of 0.2 Hz in a tensile mode
Implementation Method 2
when a free induction decay signal (FID) of the polyurethane-polyurea resin foam obtained by pulsed NMR is subjected to waveform separation
Data Source
Figure 1~2
AI summary
Provided are a polishing pad which remedies the problem of scratches occurring when a conventional hard (dry) polishing pad is used, which is excellent in polishing rate and polishing uniformity, and which can be used for not only primary polishing but also finish polishing, and a manufacturing method therefor. The polishing pad is a polishing pad for polishing a semiconductor device, comprising a polishing layer having a polyurethane-polyurea resin foam containing substantially spherical cells, wherein an M-component of the polyurethane-polyurea resin foam has a spin-spin relaxation time T2 of 160 to 260 µs, the polyurethane-polyurea resin foam has a storage elastic modulus E' of 1 to 30 MPa, the storage elastic modulus E' being measured at 40°C with an initial load of 10 g, a strain range of 0.01 to 4%, and a measuring frequency of 0.2 Hz in a tensile mode, and the polyurethane-polyurea resin foam has a density D in a range from 0.30 to 0.60 g/cm3.