Spray Coater Flow Guiding Ring Groove Design
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Solution Overview
Problem
In spray coating processes, redundant photoresist flows onto the back surface of wafers due to vacuum effects, leading to 'PR burn' during etching, reduced yield, and structural weakness of aluminum innermost ring-shaped bodies causing reliability issues in spray coaters.
Innovation Solution
A spray coater design incorporating a flow guiding ring with a groove around the vacuum chuck to capture excess photoresist, reducing its adherence to the wafer's back surface and enhancing structural integrity with a titanium-made flow guiding ring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the vacuum chuck is used to spray photoresist on the wafer, then the photoresist can be applied to the front surface of the wafer, but redundant photoresist flows to the back surface causing PR burn and reducing yield
Solution Approach 1:
The patent extracts the harmful redundant photoresist from the system by introducing a groove structure between the vacuum chuck and the wafer back surface. This groove captures and removes the excess photoresist before it can reach the wafer edge and cause PR burn, thereby resolving the contradiction between efficient photoresist application and preventing yield loss.
Solution Approach 2:
The groove acts as an intermediary structure between the vacuum chuck and the wafer back surface. It mediates the flow of redundant photoresist by providing a designated path that prevents the photoresist from directly contacting the wafer edge, thus solving the problem of PR burn while maintaining the vacuum spraying process efficiency.
2Ease of manufacture
If the innermost ring-shaped body is made of aluminum, then it can be manufactured easily, but the strength is not enough and it is easily deformed
Solution Approach 1:
The patent applies composite material design by combining the aluminum ring-shaped body with a support structure. The aluminum provides ease of manufacture while the support structure enhances strength and prevents deformation, resolving the contradiction between manufacturing ease and structural strength.
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 solution effectively prevents photoresist burning on the wafer's back surface, improves yield, and reduces abnormal vacuuming, while the titanium flow guiding ring enhances the coater's reliability by accommodating excess photoresist and preventing deformation.
Implementation Method 1
airflow generated by the vacuum chuck enables the photoresist to flow to a back surface of the wafer from the edge of the wafer, which is referred to as a 'vacuum effect'
Data Source
AI summary
A spray coater is used to spray a photoresist on a front surface of a wafer. The spray coater includes a vacuum chuck, a flow guiding ring, and a positioning ring. The vacuum chuck has a top surface and a side surface adjacent to the top surface. The wafer is located on the top surface and protrudes from the top surface of the vacuum chuck. The flow guiding ring is disposed around the vacuum chuck and has a groove. The wafer protruding from the top surface covers the flow guiding ring, and an opening of the groove faces a back surface of the wafer opposite to the front surface. The positioning ring is disposed around the flow guiding ring, such that the flow guiding ring is between the positioning ring and the side surface of the vacuum chuck.