Two-Part Susceptor Design for Uniform CVD Temperature Profiles
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Solution Overview
Problem
In CVD installations, achieving a uniform temperature profile across the susceptor, especially in the edge region, is challenging due to significant lateral temperature gradients, which affects the deposition of homogeneous layers on substrates.
Innovation Solution
A two-part susceptor design with a heat-insulating joint between the upper and lower parts, where the upper part forms the entire cup base and bearing surface, and the lower part forms the support flank, along with multiple rotationally symmetrical heating zones and a sloping edge surface to reduce thermal conduction and gradient, and an accommodating recess for a thermocouple to prevent measurement interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-part susceptor is used, then the structure is simple, but significant lateral temperature gradients occur across the bearing surface
Solution Approach 1:
The susceptor is divided into two separate parts: an upper susceptor part forming the bearing surface and a lower susceptor part forming the support flank. This segmentation allows independent optimization of each part's function and thermal characteristics, enabling better temperature control across the bearing surface while maintaining structural simplicity.
2Strength
If the entire susceptor base is made of thick material for structural strength, then strength is improved, but heating efficiency and temperature uniformity deteriorate
Solution Approach 1:
The susceptor upper part features variable thickness with different local qualities: a thicker central region for structural strength and a thinner peripheral region for improved heating efficiency and temperature uniformity. This local differentiation optimizes both mechanical strength and thermal performance without compromising either aspect.
3Ease of manufacture
If the susceptor is designed as one piece for ease of manufacture, then manufacturing is simplified, but cleaning becomes difficult requiring complete removal
Solution Approach 1:
The susceptor is segmented into an upper part (bearing surface) and a lower part (support flank) that can be separated from each other. This segmentation enables simplified cleaning operations where only the upper part needs to be removed and cleaned, while the lower part remains in place, thus improving ease of operation without significantly complicating manufacturing.
4Use of energy by moving object
If heating zones are concentrated in the center, then energy usage is reduced, but temperature uniformity across the bearing surface deteriorates
Solution Approach 1:
The susceptor upper part has non-uniform thickness distribution with a thinner peripheral region that requires less heating energy. This local quality variation allows the heating system to concentrate energy where needed (center) while the thinner edges heat up more efficiently, achieving temperature uniformity across the bearing surface with optimized energy consumption.
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 maintains a differential temperature range of less than 80°C across a 400 mm susceptor, simplifies cleaning by allowing separate removal of the cup base, and ensures a uniform temperature profile with reduced material thickness and enhanced heating efficiency.
Implementation Method 1
heat-insulating joint between the upper and lower parts... reduced thermal conduction... maintains a differential temperature range of less than 80°C
Implementation Method 2
heat-insulating joint between the upper and lower parts... reduced thermal conduction... maintains a differential temperature range of less than 80°C
Implementation Method 3
sloping edge surface to reduce thermal conduction and gradient... reduced material thickness... uniform temperature profile
Data Source
AI summary
The invention relates to a device for coating substrates having a process chamber (1) disposed in a reactor housing and a two-part, substantially cup-shaped susceptor (2, 3) disposed therein, forming an upper susceptor part (2) with the cup floor thereof having a flat plate (2′) and a lower susceptor part (3) with the cup side walls thereof, the outer side (4) of the plate (2′) of the upper susceptor part (2) facing upwards toward the process chamber (1) and forming a contact surface for at least one substrate, the upper susceptor part (2) contacting a front edge (3″) of the lower susceptor part (3) at the edge of said upper susceptor part (2), the lower susceptor part (3) being supported by a susceptor carrier (6), and heating zones (A, B, C) for heating the upper susceptor part (2) being disposed below the plate (2′). An advantageous refinement of the invention proposes that the upper susceptor part (2) be removable from the process chamber (1) separately from the lower susceptor part (3), and the joint (30) between the edge of the upper susceptor part (2) and the front edge (3″) of the lower susceptor part (3) be formed as a heat conduction barrier.