Wafer Table Cleaning Scrubber for Out-of-Focus Defect Prevention
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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 hinder accurate pattern transfer.
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 photolithography is performed without cleaning the wafer table, then productivity is maintained, but out-of-focus defects occur due to foreign particles creating uneven topography
Solution Approach 1:
The wafer table is cleaned before photolithography processing to remove foreign particles that could cause out-of-focus defects. This preliminary cleaning action prevents defects during the subsequent photolithography process, ensuring pattern transfer accuracy without requiring interruptions during production.
Solution Approach 2:
The cleaning system is integrated into the wafer table structure, allowing the table to be cleaned in-situ without requiring separate cleaning equipment or removing the wafer table from the system. This self-service capability reduces maintenance time and complexity while maintaining continuous productivity.
2Reliability
If the wafer table surface is not flat, then cleaning is required, but frequent cleaning increases maintenance time and costs
Solution Approach 1:
The wafer table surface is cleaned in advance before photolithography processing begins. This preliminary cleaning ensures the surface is free of foreign particles that could cause defects, eliminating the need for frequent interruptions during production to address contamination issues.
3Reliability
If foreign particles are present on the wafer table, then out-of-focus defects occur, but removing particles requires complex cleaning procedures
Solution Approach 1:
The cleaning scrubber is divided into multiple independent cleaning elements distributed across the wafer table surface. Each element can independently contact and clean specific areas, allowing comprehensive coverage of the entire surface without requiring a single complex cleaning mechanism. This segmented approach simplifies the overall cleaning procedure while ensuring thorough particle removal.
Solution Approach 2:
A cleaning scrubber is introduced as an intermediary tool between the wafer table and the foreign particles. The scrubber contains multiple cleaning elements that contact the particles and facilitate their removal through mechanical action, simplifying the cleaning process compared to direct manual or complex automated removal methods.
Data Source
AI summary
A method includes the following steps. A wafer table is cleaned by using a cleaning scrubber. After cleaning the wafer table, a semiconductor wafer is loaded onto the wafer table. After loading the semiconductor wafer onto the wafer table, a photolithography process is performed on the semiconductor wafer. The cleaning scrubber has microstructures protruding from a surface of the cleaning scrubber. The microstructures are spaced apart from each other and have a tapered width. The microstructures are diamond microstructures. The surface of the cleaning scrubber includes an inner annular region and an outer annular region around the inner annular region. first ones of the plurality of microstructures within the outer annular region have a height different from a height of second ones of the plurality of microstructure within the inner annular region.