Epitaxial Reactor Reflector for Uniform Substrate Cooling
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Solution Overview
Problem
Existing epitaxial deposition reactors face challenges in achieving uniform substrate temperature during both the deposition and cooling phases, leading to heat stresses and defects like 'slip lines', and require lengthy cooling periods which reduce productivity and quality.
Innovation Solution
An epitaxial deposition reactor design featuring a reflector external to the reaction chamber, with a partially reflecting upper plate that moves to reflect thermal radiation and incorporates controlled gaseous and liquid flows to manage heat transfer, allowing for uniform temperature maintenance and rapid cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heating system is deactivated and the reaction chamber is allowed to cool naturally, then the substrates are cooled from process temperature to ambient temperature, but the cooling time is lengthy (3-30 minutes) which reduces productivity
Solution Approach 1:
The invention extracts the reflector from the reaction chamber and positions it externally. This allows the reflector to be cooled independently by coolant flows (liquid or gas) while maintaining its reflective function. The decoupling of the reflector cooling system from the reaction chamber cooling system enables faster overall cooling without compromising substrate temperature uniformity.
Solution Approach 2:
The invention introduces coolant flows (liquid or gas) as intermediaries to transfer heat from the reaction chamber walls and externally from the reflector. The controlled gaseous flow between the chamber wall and reflector, and the liquid or gaseous coolant flows through/over the reflector, act as heat transfer mediators that accelerate the cooling process while maintaining temperature uniformity.
2Productivity
If the reaction chamber walls and reflector are cooled aggressively to reduce cooling time, then productivity increases, but temperature uniformity across substrates deteriorates leading to heat stresses and defects
Solution Approach 1:
The invention segments the cooling system into distinct zones: cooling of the reaction chamber walls and separate cooling of the externally positioned reflector. This segmentation allows independent control of cooling rates in different regions, enabling aggressive overall cooling while maintaining local temperature uniformity across the substrate positions through controlled gaseous flow distribution.
Solution Approach 2:
The invention employs dynamic control of coolant flows (liquid or gas) to the reflector and reaction chamber walls. By adjusting the flow rates and distribution of coolants dynamically during the cooling process, the system can accelerate cooling when temperature uniformity is maintained while preventing excessive cooling gradients that would cause defects, thus adaptively optimizing both productivity and manufacturing precision.
3Temperature
If a susceptor is placed inside the reaction chamber to support substrates, then substrates can be heated during deposition, but the susceptor retains heat during cooling extending the cooling time
Solution Approach 1:
The invention extracts the reflector from the reaction chamber interior and positions it externally. This removes a significant heat-retaining component from inside the chamber, reducing the total heat capacity that must be cooled down. The external positioning of the reflector allows it to be cooled independently and more efficiently by coolant flows, thereby reducing the overall cooling time without compromising substrate temperature control during deposition.
4Use of energy by moving object
If transparent quartz reaction chambers with reflective coating are used to reflect thermal radiation, then heating efficiency is improved, but the reflective surface is exposed to high temperatures and thermal excursions reducing reliability
Solution Approach 1:
The invention extracts the reflector from the high-temperature environment inside the reaction chamber and positions it externally in a cooler zone. This spatial separation maintains the reflector's thermal radiation reflection efficiency while exposing it to significantly lower temperatures and thermal excursions, thereby improving its durability and reliability without sacrificing heating performance.
Solution Approach 2:
The invention introduces controlled gaseous flow between the reaction chamber wall and the externally positioned reflector, and liquid or gaseous coolant flows over/through the reflector, as thermal intermediaries. These fluid mediators transfer heat away from the reflector, maintaining it at lower temperatures and reducing thermal stress, thereby improving reliability while preserving its reflective function for efficient heating during deposition.
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 solution ensures uniform substrate temperature during both deposition and cooling, reducing heat-related defects and shortening cooling times, thereby enhancing productivity and substrate quality.
Implementation Method 1
a upper plate, at least partially reflecting, which is positioned above the upper wall, at a certain distance, and which overlies at least most of the susceptor so as to reflect thermal radiation emitted by the susceptor at least in part towards the susceptor
Implementation Method 2
at least one controlled gaseous flow is established between the upper wall and the upper plate to promote the transfer of heat from the upper wall to the upper plate
Implementation Method 3
at least one controlled liquid flow is provided in or on the upper plate to cool the upper plate
Data Source
Figure 1A~1D
Figure 2
Figure 3
AI summary
The present invention relates to a reactor (1) for epitaxial deposition of semiconductor material on substrates ( 100), comprising: a reaction chamber (2) provided with a cavity (20) defined by a lower wall (21), an upper wall (22) and lateral walls (23, 24); a susceptor (3), positioned inside said cavity (20), and adapted to support and heat substrates ( 100) during epitaxial deposition; a heating system (6) adapted to heat said susceptor (3); an upper plate (7) that is positioned above said upper wall (22) and that overlies said susceptor (3) so that it reflects thermal radiation emitted by said susceptor (3) towards said susceptor (3). A liquid flow (LF) is provided in or on said upper plate (7) to cool said upper plate (7). A gaseous flow (GF) is provided between said upper wall (22) and said upper plate (7) to promote the transfer of heat from said upper wall (22) to said upper plate (7).