Multi-Part Susceptor Structure for Wafer Damage and Temperature Uniformity
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Solution Overview
Problem
Semiconductor substrates experience quality control issues due to physical interaction with susceptors during processing, leading to backside damage and temperature nonuniformities, which affect processing results.
Innovation Solution
The use of multi-part susceptors with an inner and outer portion, featuring contact pads and a thermocouple cavity with an air gap, to minimize substrate-susceptor contact and ensure temperature uniformity, along with triangular-shaped lobes for self-alignment and reduced thermal mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a susceptor supports the substrate during processing, then the substrate is held in position, but the physical interaction causes backside damage and temperature nonuniformities
Solution Approach 1:
The susceptor is divided into an inner susceptor portion and an outer susceptor portion with a gap between them. The inner portion has contact pads that minimize contact with the substrate, while the outer portion provides structural support. This segmentation reduces the physical interaction area between the susceptor and substrate, thereby reducing backside damage while maintaining substrate positioning and temperature uniformity.
2Reliability
If the susceptor contacts the substrate to hold it in position, then the substrate is stable, but temperature nonuniformities occur
Solution Approach 1:
The susceptor is segmented into inner and outer portions with a gap between them. The inner portion with minimal contact pads provides precise substrate positioning, while the outer portion provides structural support without interfering with temperature distribution. This segmentation allows stable substrate positioning while maintaining temperature uniformity across the substrate surface.
3Device complexity
If a traditional single-piece susceptor is used, then the structure is simple, but substrate damage and temperature nonuniformities increase
Solution Approach 1:
The susceptor is divided into an inner susceptor portion and an outer susceptor portion with a gap between them. The inner portion includes contact pads for minimal substrate contact, while the outer portion provides structural support. This segmentation improves substrate quality by reducing backside damage and temperature nonuniformities, while the overall structure remains relatively simple and manufacturable.
4Measurement precision
If the thermocouple is placed in direct contact with the susceptor, then temperature measurement is accurate, but thermal mass increases and temperature uniformity decreases
Solution Approach 1:
The thermocouple is positioned in the gap between the inner and outer susceptor portions, using the gap space as an intermediary location. This allows the thermocouple to measure temperature without adding significant thermal mass to the susceptor system. The thermocouple measures the temperature of the susceptor through radiation or conduction across the gap, maintaining measurement accuracy while preserving temperature uniformity.
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 design reduces backside damage and temperature nonuniformities, achieving high-quality process results with low substrate damage and accurate temperature measurements.
Implementation Method 1
A width of the cavity is larger than a width of the thermocouple, and the thermocouple is separated from walls of the cavity by an air gap
Implementation Method 2
Each of the lobes has a generally triangular shape and aligns within a corresponding one of the recesses. An apex of the triangular shape of the lobes protrudes toward a center of the inner susceptor portion
Implementation Method 3
The inner susceptor portion includes a plurality of contact pads extending outwards from and disposed along a perimeter of a surface of the inner susceptor portion, the pads configured to support the substrate and to prevent the substrate from contacting the surface during processing
Data Source
AI summary
A susceptor for semiconductor substrate processing is disclosed herein. In some embodiments, the susceptor may comprise an inner susceptor portion and an outer susceptor portion. The susceptor portions may self-align via complementary features, such as tabs on the outer susceptor and recesses on the inner susceptor portion. The inner susceptor portion may contain several contact pads with which to support a wafer during semiconductor processing. In some embodiments, the contact pads are hemispherical to reduce contact area with the wafer, thereby reducing risk of backside damage. The inner susceptor portion may contain a cavity with which to receive a thermocouple. In some embodiments, the diameter of the cavity is greater than the diameter of the thermocouple such that the thermocouple does not contact the walls of the cavity during processing, thereby providing highly accurate temperature measurements.