Multi-layer Polishing Pad Low-Pressure Uniformity
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Solution Overview
Problem
Conventional polishing pads fail to achieve uniformity and mechanical contact at low pressures, leading to non-uniform topography and potential damage to substrates like low-k dielectric materials during chemical mechanical polishing.
Innovation Solution
A polishing pad design featuring a thin, durable polishing layer with a thicker and more compressible backing layer, allowing the polishing surface to deflect and conform to the substrate at low pressures, ensuring uniform contact and reducing the risk of delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional polishing pads are used at low pressure, then substrate damage is reduced, but polishing uniformity deteriorates due to inability to achieve mechanical contact
Solution Approach 1:
The patent changes the physical parameters of the polishing pad by creating a multi-layer structure with different compressibility values. The first polishing layer has a first compressibility and the second polishing layer has a second compressibility greater than the first, allowing the pad to achieve mechanical contact at low pressures while maintaining substrate safety.
Solution Approach 2:
The invention uses a composite structure with two distinct polishing layers having different material properties. The first layer provides initial polishing contact while the second, more compressible layer ensures uniform mechanical contact across the substrate surface at low pressures, resolving the contradiction between gentle polishing and uniform contact.
2Object-affected harmful factors
If polishing pad pressure is reduced to prevent substrate damage, then substrate safety is improved, but mechanical contact uniformity deteriorates
Solution Approach 1:
The patent modifies the compressibility parameter across different layers of the polishing pad. By having the second layer with greater compressibility than the first layer, the system can operate at low pressures without compromising mechanical contact uniformity, as the more compressible layer compensates for surface irregularities.
3Stability of the object's composition
If polishing pad compressibility is increased to improve mechanical contact, then contact uniformity is improved, but pad lifetime deteriorates due to premature detachment
Solution Approach 1:
The polishing pad is segmented into two distinct layers with different compressibility characteristics. The first layer with lower compressibility provides structural support and durability, while the second layer with higher compressibility ensures uniform mechanical contact, thus extending pad lifetime while maintaining contact uniformity.
Solution Approach 2:
Different regions of the polishing pad are assigned different compressibility properties. The first layer has lower compressibility for durability, while the second layer has higher compressibility for contact uniformity. This local differentiation allows the pad to achieve both extended lifetime and improved mechanical contact uniformity simultaneously.
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
Improves polishing uniformity and extends pad lifetime by maintaining mechanical contact and preventing premature detachment, even at low pressures, thus enabling safe and effective polishing of materials sensitive to pressure.
Implementation Method 1
The backing layer has a second thickness and a second compressibility greater than the first compressibility. The first thickness, first compressibility, second thickness and second compressibility are such that the polishing surface deflects, under an applied pressure of 1.5 psi or less, more than the thickness non-uniformity of the polishing layer.
Data Source
AI summary
A polishing pad has a polishing layer and a backing layer secured to the polishing layer. The polishing layer has a polishing surface, a first thickness, a first compressibility, and a hardness between about 40 to 80 Shore D. The backing layer has a second thickness and has a second compressibility greater than the first compressibility. The first thickness, first compressibility, second thickness and second compressibility are such that the polishing surface deflects more than the thickness non-uniformity of the polishing layer under an applied pressure of 1.5 psi or less.