Support Shaft Assembly for Substrate Backside Discoloration Control
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Solution Overview
Problem
The existing processing chambers for semiconductor substrates suffer from backside contamination due to process gas deposition, leading to yield degradation, as the gas flow around the susceptor can deposit material on the substrate's back surface, causing discoloration.
Innovation Solution
The proposed solution involves a processing chamber design with a support shaft assembly that includes a disc-shaped heat plate and a ring-shaped susceptor, where a gap is maintained between the heat plate and the susceptor, allowing a purge gas to flow beneath the substrate, reducing backside contamination by minimizing gas deposition. This design includes a support shaft system with removable pins and arms that support the susceptor, creating a gap for the purge gas to flow and prevent unwanted material deposition on the substrate's back surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the susceptor is positioned close to the heat plate for efficient heating, then heating efficiency is improved, but process gas flows around the susceptor and deposits material on the back surface of the substrate causing backside discoloration
Solution Approach 1:
A purge gas flow is introduced as an intermediary between the process gas and the substrate back surface. The purge gas flows in the gap between the heat plate and susceptor, creating a protective barrier that prevents process gas from reaching and depositing on the substrate back surface, thus eliminating backside discoloration while maintaining close positioning for heating efficiency
Solution Approach 2:
The harmful process gas is extracted or removed from the gap between the heat plate and susceptor by introducing a separate purge gas flow. This creates a dedicated flow path for purge gas that actively removes or prevents the presence of process gas in the critical region where it would cause backside contamination
2Object-affected harmful factors
If a gap is created between the heat plate and susceptor to prevent backside contamination, then backside discoloration is reduced, but heating efficiency may be compromised
Solution Approach 1:
The system changes the parameters of the gas flow by introducing a separate purge gas flow with controlled rate and pressure. This allows the gap to be filled with inert purge gas rather than process gas, maintaining the protective barrier while allowing the gap to remain small enough for efficient thermal coupling between the heat plate and susceptor
3Manufacturing precision
If the susceptor is rotated to enhance uniform processing, then deposition uniformity is improved, but the complexity of the support system increases
Solution Approach 1:
The support shaft assembly combines multiple functions into a single integrated structure: it provides mechanical support for the susceptor, enables rotation for uniform processing, maintains the gap between heat plate and susceptor, and facilitates purge gas flow distribution. This merging reduces overall system complexity while achieving deposition uniformity through rotation
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 described configuration effectively reduces backside discoloration and contamination of the substrate by allowing a purge gas to flow beneath the substrate, enhancing the uniformity of the epitaxial layer deposition and improving overall yield by minimizing unwanted material deposition on the substrate's back surface.
Implementation Method 1
The susceptor is heated in order to heat the substrate to a desired processing temperature. One method used to heat the susceptor is by the use of lamps provided around the chamber. The lamps direct light into the chamber and onto the susceptor.
Implementation Method 2
The disc shaped heat plate is support by the support shaft system. The ring shaped susceptor is supported by the plurality of pins in the support shaft system such that there is a gap defined between the heat plate and the susceptor.
Implementation Method 3
The purge gas flows beneath the substrate, in the gap defined between the heat plate and the susceptor.
Implementation Method 4
The temperature may be measured using an infrared temperature sensor, which detects the infrared radiation emitted from the heated susceptor.
Implementation Method 5
A flow of a processing gas is provided in the top of chamber and across the surface of the substrate.
Implementation Method 6
During processing some of the process gas may flow around the edge of the susceptor and deposit a layer of the material on the back surface of the substrate.
Data Source
AI summary
A processing chamber for processing a substrate is disclosed herein. In one embodiment, the processing chamber includes a support shaft assembly. The support shaft assembly has a ring shaped susceptor, a disc shaped heat plate, and a support shaft system. The support shaft system supports the susceptor and the heat plate, such that the susceptor is supported above the heat plate defining a gap between the heat plate and the susceptor. In another embodiment, the heat plate includes a plurality of grooves and the susceptor includes a plurality of fins. The fins are configured to sit within the grooves such that the susceptor is supported above the heat plate, defining a gap between the heat plate and the susceptor. In another embodiment, a method of processing a substrate in the aforementioned embodiments is disclosed herein.