CMP Pad Local Area Transparency Recessed Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional CMP polishing pads with local area transparencies (LATs) face issues such as LAT delamination during polishing due to lateral frictional forces, and imperfect seals leading to polishing slurry leakage and compromised optical clarity for endpoint detection.
Innovation Solution
A CMP polishing pad with a recessed LAT and strong covalent bonding between the LAT and opaque regions, featuring a thermoset polyurethane or polyurea composition with microcellular structure and porosity for improved durability and slurry flow, and a plateau plane surrounding the LAT for enhanced manufacturing and endpoint detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the LAT is mounted flush with the polishing surface, then the manufacturing process is simpler, but the LAT becomes scratched and clouded during polishing and conditioning resulting in polishing defects and compromised endpoint detection
Solution Approach 1:
The LAT is transitioned from a flush-mounted configuration to a recessed configuration, moving it to a different dimensional plane below the polishing surface. This dimensional change protects the LAT from direct contact with polishing tools while maintaining its optical function for endpoint detection.
2Reliability
If the LAT is recessed from the polishing surface, then scratching and clouding are avoided, but the seal between the polishing pad and LAT may be imperfect leading to slurry leakage
Solution Approach 1:
A flexible sealing layer is introduced between the polishing pad and the recessed LAT. This thin film conformally seals the recessed area, preventing slurry leakage while accommodating the LAT's recessed position and maintaining the protective configuration.
3Strength
If adhesive is used to attach the LAT to the polishing pad, then the LAT can be secured in place, but the adhesive interface may be compromised by polishing slurry causing LAT separation and ejection
Solution Approach 1:
The flexible sealing layer serves as an intermediary between the polishing pad and the LAT. Instead of using adhesive that can be compromised by slurry, the flexible film creates a mechanical and chemical bond that is resistant to slurry degradation, preventing LAT separation and ejection.
4Ease of manufacture
If conventional adhesive or integral molding methods are used, then the LAT can be attached to the polishing pad, but the seal deteriorates during use allowing slurry to leak through and compromise optical clarity
Solution Approach 1:
The sealing mechanism is changed from adhesive-based attachment to flexible film-based sealing. This parameter change in the sealing approach maintains seal integrity under dynamic polishing conditions, preventing slurry leakage while preserving optical clarity for endpoint detection.
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 prevents LAT delamination and maintains optical clarity for effective endpoint detection, ensuring reliable polishing and planarization of semiconductor wafers by providing a robust and efficient polishing pad with improved wear resistance and slurry management.
Implementation Method 1
thermoset polyurethane or polyurea composition with microcellular structure and porosity
Implementation Method 2
The polishing slurry typically contains one or more chemicals that interact with or dissolve portions of the uppermost wafer layer(s)
Implementation Method 3
an abrasive material that physically removes portions of the layer(s)
Implementation Method 4
strong covalent bonding between the LAT and opaque regions
Data Source
Figure 1~2
Figure 3~5
AI summary
A CMP polishing pad comprising (a) a polishing layer having a polishing surface and a back surface opposite said polishing surface; said polishing layer having at least one cured opaque thermoset polyurethane region and at least one aperture region; said at least one cured opaque thermoset region has a porosity from about 10% to about 55% by volume; said at least one aperture region having (1) a top opening positioned below the polishing surface, (2) a bottom opening that is co-planar with said back surface and (3) straight line vertical sidewalls extending from said aperture top opening to said aperture bottom opening; said at least one aperture region filled with a cured plug of thermoset polyurethane local area transparency material that has a light transmission of less than 80% at a wavelength from 700 to 710 nanometers and is chemically bonded directly to a thermoset polyurethane opaque area; (b) an aperture-free removable release sheet covering at least a portion of said back surface of the polishing layer; and (c) an adhesive layer interposed between said polishing layer and said release sheet; said adhesive layer capable of adhering the polishing layer to a platen of a CMP apparatus after said release sheet has been removed.