Wafer Backside Polishing Guided by Piezoelectric Topography Sensing
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Solution Overview
Problem
Existing semiconductor manufacturing processes result in foreign objects, film residue, and uneven films on the backside of wafers, leading to defocusing issues during exposure processes, which affect imaging quality and pattern profiles.
Innovation Solution
A system and method utilizing a vacuum stage with piezoelectric elements to detect deformations on the wafer backside, transmitting data to a polishing device for customized pressure-based polishing to flatten the surface, removing contaminants and defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional manufacturing processes (etching, deposition, diffusion) are performed on wafers, then semiconductor devices are produced, but foreign objects, film residue, and uneven films remain on the backside of wafers causing defocusing issues
Solution Approach 1:
The system performs preliminary detection of wafer backside topography using piezoelectric elements before the polishing step. This allows the polishing process to be precisely targeted and controlled, removing contaminants and flattening the surface without requiring excessive material removal, thereby resolving the contradiction between maintaining productivity and improving manufacturing precision.
Solution Approach 2:
The polishing apparatus applies localized polishing pressure to specific regions of the wafer backside based on detected topography variations. By concentrating polishing action only where needed (at locations with foreign objects, film residue, or unevenness), the system achieves high flatness improvement while minimizing overall processing time and material removal, thus resolving the contradiction between productivity and manufacturing precision.
2Manufacturing precision
If fixed pressure polishing is applied to wafer backside, then flattening is achieved, but over-polishing may occur causing wafer damage
Solution Approach 1:
The system incorporates real-time feedback through piezoelectric elements that detect wafer backside topography during the polishing process. The detected deformation data is fed back to control the polishing pressure dynamically, allowing the system to stop polishing in regions that have achieved sufficient flatness and avoid applying excessive pressure that could cause wafer damage, thus resolving the contradiction between manufacturing precision and reliability.
Solution Approach 2:
The polishing pressure is made dynamic rather than fixed, adjusting in real-time based on the detected wafer topography. The system applies higher pressure to regions with greater deformations and reduces or stops pressure in regions that are already sufficiently flat, preventing over-polishing and wafer damage while achieving the required flatness, thereby resolving the contradiction between manufacturing precision and reliability.
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 system improves the flatness of the wafer backside, reducing defocusing issues and enhancing the performance of exposure processes by maintaining wafer integrity and preventing over-polishing.
Implementation Method 1
The stage can include piezoelectric elements configured to sense a topography of the backside of the wafer. For example, the piezoelectric elements can be configured to detect deformations on the backside of the wafer.
Implementation Method 2
placing the wafer on a vacuum stage
Data Source
AI summary
A system and a method for manufacturing a semiconductor device are provided. The system includes a processor, a stage for supporting a first wafer, and a polishing device. The stage is configured to sense characteristic data of a first surface of the first wafer, wherein the stage is electrically coupled to the processor and configured to transmit the sensed characteristic data of the first surface of the first wafer to the processor. The polishing device is electrically coupled to the processor and configured to remove foreign objects from the first surface of the first wafer based on the sensed characteristic data.