Edge Ring Temperature Control for Wafer Uniformity
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Solution Overview
Problem
Current rapid thermal processing (RTP) systems face challenges in achieving uniform temperature profiles across semiconductor substrates, particularly near the edge, due to overlapping thermal properties between the substrate and edge ring, leading to temperature deviations of 1° C. to 1.5° C., which is crucial for processes like thermal oxidation and spike anneal.
Innovation Solution
The implementation of a rapid thermal processing chamber with a temperature-controlled edge ring, where the edge ring is independently heated by a separate heat source, allowing for independent control of its temperature, which differs from the substrate's target temperature, to enhance temperature uniformity across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single heat source is used to heat the substrate, then the heating process is simple, but temperature uniformity across the substrate deteriorates due to edge ring interference
Solution Approach 1:
The heating system is segmented into two independent heat sources: a first heat source for heating the substrate and a second heat source for heating the edge ring. This segmentation allows independent control of each heating zone, enabling the edge ring temperature to be adjusted separately to compensate for edge effects and achieve uniform substrate temperature distribution.
Solution Approach 2:
The second heat source is specifically applied to the edge ring region to provide localized heating compensation. By independently controlling the edge ring temperature through this dedicated heat source, the system addresses the local thermal non-uniformity at the substrate edge caused by the overlap between substrate and edge ring, thereby improving overall temperature uniformity.
2Ease of operation
If the edge ring and substrate overlap for support, then mechanical support is provided, but temperature control precision deteriorates due to complicated heating situation near the edge
Solution Approach 1:
The edge ring serves as an intermediary element between the substrate support structure and the thermal field. By independently heating the edge ring through the second heat source, the system mediates the thermal interaction between the substrate and support structure, compensating for the complicating effect of their overlap and enabling more precise temperature control at the substrate edge.
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 approach achieves temperature uniformity with deviations of less than 1° C. to 1.5° C. across the substrate, even at high temperatures up to 1350° C., effectively addressing the non-uniformity issues near the edge and improving the precision of RTP processes.
Implementation Method 1
thermal radiation is generally used to rapidly heat a substrate
Implementation Method 2
The substrate may be provided additional heat by a heated susceptor conductively coupled to the substrate
Implementation Method 3
a second heat source configured to heat the edge ring
Implementation Method 4
the edge ring is independently heated by a separate heat source
Implementation Method 5
a reflective surface on the back side reflects heat back to the substrate
Data Source
AI summary
The present invention provides apparatus and methods for achieving uniform heating to a substrate during a rapid thermal process. More particularly, the present invention provides apparatus and methods for controlling the temperature of an edge ring supporting a substrate during a rapid thermal process to improve temperature uniformity across the substrate.