Polishing Membrane Structure for Low-Damage Substrate Backside Contact
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Solution Overview
Problem
During substrate backside polishing in semiconductor manufacturing, the pattern surface of the substrate is prone to damage from particles, scratches, and static electricity due to direct contact with the membrane, necessitating a structure that minimizes such damage.
Innovation Solution
A membrane with an annular side wall, a bottom flap extending inward, and an upper flap connected to a carrier head forms a pressure chamber, allowing pressure transmission to the substrate while minimizing contact area, using pressurizing units to control the degree of contact and pressure applied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the membrane contacts the substrate directly during polishing, then polishing can be performed, but the pattern surface is damaged by particles, scratches, and static electricity
Solution Approach 1:
The patent introduces a membrane as an intermediary component between the carrier head and the substrate. The membrane contacts only the outermost portion of the substrate while transmitting pressure through an internal pressure chamber, thereby enabling the polishing process while protecting the pattern surface from direct contact with the carrier head and potential sources of damage such as particles, scratches, and static electricity.
2Force
If the membrane contacts the entire substrate surface, then pressure can be applied effectively, but the contact area increases causing more damage to the pattern surface
Solution Approach 1:
The patent applies local quality by designing the membrane to contact only the outermost portion of the substrate rather than the entire surface. The bottom flap of the membrane is configured to extend inward from the lower end of the side wall to form a hollow, creating a localized contact zone that concentrates pressure where needed while minimizing the overall contact area with the pattern surface.
Solution Approach 2:
The membrane is segmented into distinct functional regions: a side wall forming an annular structure, a bottom flap extending inward to create a hollow, and an upper flap connecting to the carrier head. This segmentation allows the membrane to transmit pressure through the hollow structure while maintaining minimal contact with the substrate's pattern surface.
3Strength
If a solid membrane structure is used, then structural integrity is maintained, but pressure control precision is reduced
Solution Approach 1:
The patent incorporates a pressure chamber within the membrane structure that can be controlled by pressurizing units. This pneumatic/hydraulic system allows for precise control of the downward pressure applied to the substrate while maintaining the structural integrity of the membrane. The pressure chamber enables adjustable pressure transmission without requiring a solid, rigid membrane structure.
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 effectively reduces damage to the substrate pattern surface by minimizing contact area and controlling pressure application, ensuring precise polishing without surface impairment.
Implementation Method 1
a pressure chamber formed between a lower surface of the carrier head, the upper flap, the side wall, the bottom flap, and an upper surface of the substrate
Implementation Method 2
a first pressurizing unit configured to control an internal pressure of the pressure chamber in order to control a downward pressure applied to the substrate
Implementation Method 3
a second pressurizing unit configured to control an internal pressure of the upper chamber in order to control a vertical position of the bottom flap or a degree of contact between the bottom flap and the substrate
Data Source
AI summary
A substrate polishing device includes a carrier head, a membrane connected to the carrier head, and a retainer ring connected to the carrier head to surround an outer side of the membrane. The membrane includes a side wall formed in an annular shape, a bottom flap extending in an inward direction from a lower end of the side wall and intended to come in direct contact with a substrate, and an upper flap extending from an upper end of the side wall and intended to connect to the carrier head.