Edge Ring Thermal 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 interactions with edge rings and varying thermal properties, leading to thermal stress and non-uniform processing results.
Innovation Solution
The implementation of a chamber design with independent control of edge ring temperature using a thermal mass with fluid channels, along with a gas jet for cooling, and a reflector plate to enhance temperature uniformity, allowing for precise heating and cooling of the edge ring to match or differ from the substrate temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single heat source is used to heat the substrate, then the heating rate can be rapid, 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 each heat source to be optimized for its specific function, enabling rapid heating while maintaining temperature uniformity by independently controlling the substrate and edge ring temperatures.
Solution Approach 2:
Different regions of the system are provided with different thermal properties through localized heating. The edge ring region receives dedicated heating from the second heat source to compensate for its different thermal characteristics compared to the substrate center, ensuring uniform temperature distribution across the entire substrate surface.
2Device complexity
If the edge ring temperature is not controlled independently, then the system structure remains simple, but thermal stress increases due to temperature gradients
Solution Approach 1:
The temperature control system is segmented into independent control loops for the substrate and edge ring. The second heat source is independently controllable from the first heat source, allowing the edge ring temperature to be adjusted separately to match or differ from substrate temperature as needed, thereby minimizing thermal stress without significantly increasing system complexity.
Solution Approach 2:
The edge ring is pre-heated or cooled by the second heat source before substrate processing to prevent thermal stress. By controlling the edge ring temperature to match or differ from the substrate temperature in advance, the system prevents thermal gradients that would cause stress, warpage, or defect generation during processing.
3Device complexity
If conventional heating methods are used, then the equipment is simple, but temperature deviation from center to edge exceeds acceptable limits
Solution Approach 1:
The heating system divides the thermal control into two independent zones: substrate heating and edge ring heating. This segmentation enables precise control of temperature distribution by independently adjusting the second heat source for the edge ring to compensate for edge effects, achieving temperature deviation of less than 1-2°C across the substrate.
Solution Approach 2:
The system applies different thermal treatments to different regions: the substrate center is heated by the first heat source while the edge ring receives dedicated heating from the second heat source. This local quality approach addresses the specific thermal needs of each region, ensuring uniform temperature distribution despite the inherent edge effects in conventional heating.
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 of less than 1-2°C deviation across the substrate, even at high temperatures up to 1350°C, improving processing consistency and reducing thermal stress by dynamically controlling the edge ring temperature.
Implementation Method 1
a thermal mass positioned adjacent the edge ring including at least one channel containing a fluid that heats or cool the thermal mass
Implementation Method 2
a gas jet for cooling
Implementation Method 3
a reflector plate to enhance temperature uniformity
Data Source
AI summary
Apparatus and methods for achieving uniform heating or cooling of a substrate during a rapid thermal process are disclosed. More particularly, apparatus and methods for controlling the temperature of an edge ring supporting a substrate and/or a reflector plate during a rapid thermal process to improve temperature uniformity across the substrate are disclosed, which include a thermal mass or plate adjacent the edge ring to heat or cool the edge ring.