Polishing Head Tilt Adjustment for Bent Wafer Uniformity
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Solution Overview
Problem
The existing polishing apparatuses face challenges in uniformly pressing a polishing tape against a bent substrate, leading to non-uniform polishing rates due to the tilting of the pressing member caused by friction.
Innovation Solution
A polishing head with a tilt adjustment mechanism that inclines the pressing member at a fixed angle, allowing it to maintain uniform pressure on the polishing tape against the bent substrate, thereby ensuring uniform polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the polishing tape is pressed against the wafer by the pressing member, then the polishing action is achieved, but the wafer is bent upward causing non-uniform pressing
Solution Approach 1:
The pressing member is pre-adjusted to a tilted position before polishing begins. This preliminary tilting compensates for the wafer bending that occurs during polishing, allowing the pressing member to maintain uniform contact with the polishing tape across the wafer surface even as the wafer bends upward under pressure.
2Ease of operation
If the pressing member is forced to tilt due to polishing tape movement, then friction is generated, but the pressing member cannot follow the bending of the wafer
Solution Approach 1:
The pressing member's tilt angle is pre-adjusted to account for the friction-induced bending and wafer deformation. By setting the correct tilt angle before polishing begins, the pressing member maintains proper alignment and uniform pressing force throughout the polishing process, preventing loss of uniformity despite friction forces.
Solution Approach 2:
The tilt angle of the pressing member is adjusted as a key parameter to compensate for friction effects. By changing this geometric parameter, the system adapts to the friction-induced forces and maintains uniform pressing across the wafer surface during polishing.
3Productivity
If the polishing tape moves in the direction of arrow Z, then polishing progresses, but friction causes the pressing member to tilt and lose uniform pressure
Solution Approach 1:
The pressing member is pre-positioned with the correct tilt angle to counteract the friction effects that will occur as the polishing tape moves in the arrow Z direction. This preliminary adjustment ensures that even as polishing progresses and friction acts on the system, the pressing member maintains uniform pressure distribution.
Solution Approach 2:
The tilted position of the pressing member creates a counteracting geometric configuration that compensates for the friction-induced tilting. By pre-establishing this counter-tilt, the system anticipates and neutralizes the harmful effect of friction on pressing uniformity during the polishing process.
Data Source
AI summary
The present invention relates to a polishing head for pressing a polishing tape against a substrate, such as a wafer. The present invention further relates to a polishing apparatus for polishing a substrate with such a polishing head. The polishing head (10) includes: a pressing member (12) configured to press a polishing tape (2) against the substrate (W); an actuator (15) configured to move the pressing member (12) in a predetermined pressing direction (CL) and apply a pressing force to the pressing member (12); and a tilt adjustment mechanism (40) configured to adjust tilt of the pressing member (12) with respect to the pressing direction (CL). The tilt adjustment mechanism (40) is configured to tilt the pressing member (12) with respect to the pressing direction (CL) and maintain an angle of the tilted pressing member (12).