SiC Wafer Table Scrubber for Photolithography Focus Stability
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the occurrence of out-of-focus defects during photolithography due to foreign particles on the wafer backside, which create uneven topography and affect the focus of exposure areas.
Innovation Solution
A cleaning method using a cleaning scrubber with microstructures designed to remove foreign particles from the wafer table, ensuring a flat and clean surface for precise photolithography processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional cleaning method is used on the wafer table, then the cleaning process is simple, but foreign particles remain on the wafer backside causing out-of-focus defects
Solution Approach 1:
The cleaning scrubber is segmented into multiple microstructures (protrusions) arranged in arrays, where each microstructure independently contacts and cleans specific regions of the wafer backside. This segmentation allows thorough cleaning of foreign particles while maintaining a manageable overall structure that can be integrated into the wafer table system.
Solution Approach 2:
The cleaning approach transitions from a conventional two-dimensional surface cleaning method to a three-dimensional cleaning mechanism. The microstructures protrude from the wafer table surface into the wafer backside trenches, enabling cleaning in the vertical dimension and effectively removing particles that conventional planar cleaning methods cannot reach.
2Manufacturing precision
If the wafer table surface is not cleaned, then the cleaning process is fast, but out-of-focus defects occur during photolithography
Solution Approach 1:
The cleaning scrubber performs preliminary cleaning action during wafer loading or between wafers, removing foreign particles before they can cause out-of-focus defects during photolithography. This preventive cleaning approach ensures wafer surface flatness is maintained without requiring extensive post-contamination maintenance time.
3Object-affected harmful factors
If a simple cleaning method is used, then the cleaning process is easy to operate, but foreign particles are not effectively removed from trenches
Solution Approach 1:
The microstructures on the cleaning scrubber are designed to automatically contact and clean the wafer backside trenches through the natural positioning of the wafer on the wafer table. The cleaning action occurs self-service style during normal wafer handling operations, eliminating the need for complex manual cleaning procedures while effectively removing foreign particles.
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 cleaning scrubber effectively removes contaminants, preventing out-of-focus defects and improving yield by ensuring accurate pattern transfer during photolithography, reducing maintenance time and costs.
Implementation Method 1
A cleaning method using microstructures with specific geometry shapes on a cleaning scrubber to effectively remove foreign particles from the wafer table
Data Source
AI summary
An exposure module includes a light source, a photomask situated optically downstream of the light source, and a wafer table situated optically downstream of the photomask. The wafer table includes a plurality of silicon carbide (SiC) crystalline structures separated from each other by trenches. The exposure module further includes a cleaning scrubber operative to clean the wafer table. The cleaning scrubber includes a circular surface and a plurality of microstructures extending from the circular surface. The microstructures are tapered from a first width to a second width in a direction away from the circular surface. The second width is less than a width of the plurality of trenches between the SiC crystalline structures of the wafer table.