Wafer Backside Brush Cleaning for Lithography Exposure Accuracy
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Solution Overview
Problem
Contaminants on the backside of semiconductor wafers can lead to inaccurate exposure and reduced quality of the photoresist pattern, as they can cause the wafer to be tilted and increase its height, affecting the lithography process.
Innovation Solution
A wafer cleaning system that includes a wafer edge exposure apparatus and a backside treatment apparatus, utilizing a brush element with a control device to perform specific cleaning processes based on the location and type of contaminants, with different speeds, forces, and rotational speeds to effectively remove contaminants from the backside of the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If contaminants are present on the backside of the wafer, then the wafer height increases and tilting occurs, but this leads to inaccurate exposure and reduced photoresist quality
Solution Approach 1:
The backside of the wafer is cleaned before the lithography process to remove contaminants. This preliminary cleaning action prevents contaminants from causing wafer tilting and height increase during subsequent exposure, thereby ensuring accurate exposure and high-quality photoresist patterns.
2Reliability
If a brush element is used to clean the backside of the wafer, then contaminants can be removed effectively, but the cleaning process becomes more complex
Solution Approach 1:
The brush element is configured to rotate and contact the backside of the wafer automatically during the cleaning process. The rotation of the brush element and its controlled movement across the wafer surface enable self-service cleaning without requiring complex external manipulation mechanisms, thus achieving effective contaminant removal while limiting system complexity.
3Manufacturing precision
If different cleaning processes are applied based on contaminant location, then cleaning precision improves, but the control system becomes more complex
Solution Approach 1:
The cleaning system applies different cleaning processes to different regions of the wafer backside based on contaminant location. The brush element can be controlled to apply varying pressure, rotation speed, or movement patterns to specific areas where contaminants are detected, achieving high cleaning precision while using a relatively simple control mechanism that adjusts parameters locally rather than requiring a completely complex control system.
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 ensures a flat backside of the wafer, preventing tilting and height increase, allowing for accurate exposure and improving the quality of the exposed photoresist by effectively removing contaminants.
Implementation Method 1
a brush head configured to rotate on the brush holder
Implementation Method 2
perform a first cleaning process to the brush element when the brush element is located at a clear area, and perform a second cleaning process when the brush element is located at an unclear area
Data Source
AI summary
A wafer cleaning system is provided, including pins configured to support a wafer; a brush element including a brush holder movable relative to the wafer, and a brush head configured to rotate on the brush holder; a control device configured to control the brush element; an inspection device configured to inspect the backside of the wafer and generate an inspection signal; and a process module configured to generate a control signal according to the inspection signal, wherein the control signal includes movement information of the brush element according to coordinates of the contaminants obtained from the inspection signal, wherein control device is configured to control the brush element to clean the backside of the wafer along a first path according to the control signal when the wafer is disposed on the pins.