Carrier Head Membrane Structure for Uniform CMP Wafer Pressure
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Solution Overview
Problem
The presence of unexpected non-uniform pressure in the chamber between the flexible membrane and the carrier head substrate affects the precision and efficiency of substrate planarization during chemical mechanical polishing, especially as integrated circuits become smaller and denser.
Innovation Solution
A carrier head membrane with a main portion, vertical and horizontal portions, and outer periphery portions, featuring pressurizable regional chambers and a groove in the junction portion, allows for controlled pressure distribution and enhanced polishing efficiency by varying air pressure within these chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a flexible membrane is installed on the carrier head to apply pressure for planarization polishing, then the substrate can be held and pressed against the polishing pad, but non-uniform pressure occurs in the chamber between the flexible membrane and the carrier head substrate
Solution Approach 1:
The chamber is divided into multiple pressurizable regional chambers by partition walls extending from the carrier head substrate. This segmentation allows independent pressure control in different regions, enabling uniform pressure distribution across the flexible membrane and preventing non-uniform pressure application that would affect polishing precision.
Solution Approach 2:
Different regions of the chamber are equipped with independent pressure control capabilities through the partition wall structure. This allows local pressure adjustment in specific areas of the flexible membrane, ensuring that each region receives the appropriate pressure for optimal polishing while maintaining overall uniformity.
2Productivity
If the chamber is pressurized to hold the wafer and apply pressure for polishing, then the substrate planarization can be achieved, but unexpected non-uniform pressure affects the planarization results
Solution Approach 1:
The chamber is divided into multiple pressurizable regional chambers by partition walls extending from the carrier head substrate. This segmentation allows independent pressure control in different regions, enabling uniform pressure distribution across the flexible membrane and preventing non-uniform pressure application that would affect polishing precision.
Solution Approach 2:
The pressure parameters in different regional chambers can be independently adjusted and controlled. By varying the pressure in each region according to specific requirements, the system achieves both high polishing efficiency and precise planarization quality, eliminating the trade-off between productivity and precision.
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 enables improved control over wafer flatness and material removal, enhancing polishing efficiency and reducing contamination risks by ensuring uniform pressure application and preventing chemical contact with the wafer.
Implementation Method 1
The chamber behind the flexible membrane is pressurized by gas or vacuumed to hold the wafer, causing the flexible membrane to expand outward and thereby apply pressure to the substrate for planarization polishing
Implementation Method 2
a groove is provided in a circumferential junction portion between the main portion and the outer ring portion, which is located in the regional chamber and recessed toward an inner wall surface of the circumferential junction portion
Data Source
AI summary
A carrier head membrane for use in a polishing head, comprising a main portion, a vertical portion, a horizontal portion, and an outer ring portion. The main portion is substantially flat and includes a working surface for contacting the backside of a wafer. The vertical portion extends substantially vertically from the main portion, the horizontal portion extends from the vertical portion, and the outer ring portion extends substantially vertically from an outer edge of the main portion. A plurality of pressurizable regional chambers are defined between the main portion and the polishing head, and a groove is formed at a circumferential junction portion between the main portion and the outer ring portion, recessed toward an inner wall surface of the circumferential junction portion and located within the regional chamber.