Vertical Wafer Mounting in Plasma Etching to Prevent Particle Fallout
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Solution Overview
Problem
The plasma etching process in semiconductor manufacturing generates negatively charged by-products that are suspended above the wafer due to magnetic and electric field interactions, causing contamination on the top surface of the wafer.
Innovation Solution
A method where a wafer is positioned on a wafer-mounting surface parallel to the gravity direction within an etching device, with a gas excited into plasma using an inductive coil, and particles are removed through exhaust pipes, preventing them from contaminating the top surface of the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma etching process is used for photoresist stripping, then processing accuracy and productivity are improved, but particle contamination on wafer surface worsens
Solution Approach 1:
The patent inverts the conventional horizontal wafer mounting orientation to a vertical orientation where the wafer surface is perpendicular to the chamber floor. This inversion changes the gravity-driven particle deposition pattern from landing on the wafer surface to falling along the wafer edges, thereby resolving the contamination issue while preserving plasma etching benefits
Solution Approach 2:
The patent transitions from a two-dimensional horizontal wafer mounting approach to a three-dimensional vertical configuration. By rotating the wafer 90 degrees and mounting it vertically on the chamber wall, particles are directed to deposit on the wafer's side surfaces rather than its processing surface, effectively separating contamination paths from critical areas
2Stability of the object's composition
If wafer is mounted horizontally during plasma etching, then process uniformity is maintained, but particle accumulation on top surface increases
Solution Approach 1:
The patent inverts the conventional horizontal wafer mounting orientation to a vertical orientation where the wafer surface is perpendicular to the chamber floor. This inversion changes the gravity-driven particle deposition pattern from landing on the wafer surface to falling along the wafer edges, thereby resolving the contamination issue while preserving plasma etching benefits
Solution Approach 2:
The patent transitions from a two-dimensional horizontal wafer mounting approach to a three-dimensional vertical configuration. By rotating the wafer 90 degrees and mounting it vertically on the chamber wall, particles are directed to deposit on the wafer's side surfaces rather than its processing surface, effectively separating contamination paths from critical areas
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
This method effectively prevents particle contamination on the top surface of the wafer, improving its performance by ensuring particles drop on the side surfaces instead, thus maintaining a clean and functional wafer.
Implementation Method 1
An inductive coil wrapping around a vacuum sealing device excites the gas into plasma
Implementation Method 2
The plasma is injected to the wafer
Implementation Method 3
performing a purging operation through at least one exhaust pipe connected to the chamber
Implementation Method 4
the wafer-mounting surface of the wafer holder is in parallel with a gravity direction, and thus particles may drop on a side surface of the wafer without dropping on a top surface of the wafer
Data Source
AI summary
A method includes the following steps. A wafer is disposed on a wafer-mounting surface of a wafer holder that is disposed in a chamber. The wafer-mounting surface is in parallel with a gravity direction. A gas is flown from a gas source to vacuum sealing device. An inductive coil wrapping around a vacuum sealing device excites the gas into plasma. The plasma is injected to the wafer.