PECVD Backside Deposition Using Purge-Showerhead Wafer Stress Balancing
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Solution Overview
Problem
Semiconductor wafers experience warping and stress due to the buildup of layers on the top-side during deposition, which can affect subsequent processing steps and lead to increased handling issues and reduced processing yield when attempting to counteract this by depositing materials on the back-side.
Innovation Solution
A plasma processing system with a shower-pedestal configured to supply process gases for backside deposition, while a showerhead provides purge gases to prevent deposition on the top-side, allowing for the controlled deposition of films on both sides of the wafer using a dual gas-flowing electrode setup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the wafer is flipped and loaded back-side up for deposition, then materials can be deposited on the back-side to counteract wafer bowing, but additional handling and particle exposure increase, reducing processing yield
Solution Approach 1:
Instead of flipping the wafer to deposit on the back-side, the invention inverts the approach by keeping the wafer front-side up and using a shower-pedestal to deliver process gases through the back-side of the wafer. This allows back-side deposition without wafer flipping, eliminating additional handling and particle exposure while maintaining the ability to counteract wafer bowing.
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 solution effectively counteracts wafer warping by depositing films on the back-side to balance stress from top-side deposition, minimizing bowing and stress, and maintaining processing yield by reducing handling and particle exposure.
Implementation Method 1
A radio frequency (RF) power supply for providing power to the showerhead to generate a plasma is provided. The plasma is used for depositing a film on a back-side of the substrate
Implementation Method 2
The shower-pedestal is configured to supply process gases from a plurality of holes, which enable delivery of process gases for deposition of materials onto the backside of the substrate
Implementation Method 3
The showerhead, in one embodiment, is configured to supply purge gases, e.g., inert gases, to prevent the backside deposition gases from forming materials layers on the topside of the substrate
Data Source
AI summary
A plasma processing system is provided. The system includes a chamber, a controller and a showerhead disposed in the chamber. A first gas manifold is connected to the showerhead for providing a first gas from a first gas source responsive to control from the controller. A shower-pedestal is disposed in the chamber and oriented opposite the showerhead. A second gas manifold is connected to the shower-pedestal for providing a second gas from a second gas source responsive to control from the controller. A substrate support for holding a substrate at a spaced apart relationship from the shower-pedestal is provided. A radio frequency (RF) power supply for providing power to the showerhead to generate a plasma is provided. The plasma is used for depositing a film on a back-side of the substrate, when present in the chamber. The substrate is held by the substrate support in the spaced apart relationship from the shower-pedestal, during backside deposition. The showerhead provides a purge gas during the backside deposition.