Lamphead Insert Tube Collimates Radiant Energy for Uniform Heating
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Solution Overview
Problem
Rapid thermal processing systems face challenges in achieving temperature uniformity over semiconductor substrates, which is crucial for consistent film deposition, oxide growth, and annealing processes, as existing lamp assemblies do not effectively collimate radiant energy to ensure uniform heating.
Innovation Solution
The introduction of an improved lamphead assembly featuring an insert tube or cap with a constant inner diameter and tapered upper portion, which collimates radiant energy from the lamp towards the substrate, combined with a specular reflector, enhances optical efficiency and uniformity of light distribution, and serves as a cooling path to extend lamp life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional lamp assembly with reflector sleeve is used, then radiant energy is reflected toward the substrate, but temperature uniformity over the substrate surface deteriorates due to ineffective collimation of radiant energy
Solution Approach 1:
An insert tube is introduced as an intermediary component between the lamp and substrate. This insert tube has a constant inner diameter section that collimates radiant energy from the lamp, transforming the divergent radiation into parallel beams that uniformly illuminate the substrate surface, thereby resolving the temperature uniformity issue
Solution Approach 2:
The insert tube changes the geometric parameters of radiant energy propagation by providing a constant inner diameter section that maintains parallel ray paths. This parameter control (constant diameter) ensures uniform energy distribution across the substrate, improving temperature uniformity during processing
2Power
If radiant energy is intensified to improve processing efficiency, then power delivery increases, but lamp life deteriorates due to excessive thermal stress
Solution Approach 1:
The insert tube acts as a thermal intermediary that manages radiant energy distribution. By collimating the energy, it delivers higher effective power to the substrate while distributing the thermal load more evenly, reducing peak thermal stress on the lamp and extending its operational life
Solution Approach 2:
The insert tube creates different functional zones: a constant inner diameter section for collimation and energy delivery, and a tapered section for energy distribution. This local quality differentiation enables high power delivery to the substrate while protecting the lamp from excessive thermal stress through optimized energy pathways
3Productivity
If radiant energy is concentrated to improve processing speed, then power delivery increases, but temperature uniformity deteriorates due to limited area radiation
Solution Approach 1:
The insert tube serves as an optical intermediary that first collimates energy in its constant diameter section, then distributes it uniformly across the substrate through its tapered section. This two-stage process maintains high processing speed while ensuring temperature uniformity
Solution Approach 2:
The insert tube is segmented into functional sections: a constant inner diameter section for collimation and a tapered section for distribution. This segmentation allows the system to achieve both high power delivery (through collimation) and uniform temperature distribution (through the tapered expansion), resolving the contradiction between processing speed and 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 configuration achieves up to 50% more power delivery to the substrate with improved temperature uniformity and extended lamp life by effectively collimating and distributing radiant energy, addressing the issue of non-uniform heating in RTP systems.
Implementation Method 1
the insert tube collimates radiant energy from the lamp toward the substrate support
Implementation Method 2
The reflector, the insert cap, and the lamp housing tube are generally coaxial
Implementation Method 3
During processing, infrared radiation from the lamps radiate onto a rotating semiconductor substrate in the processing chamber
Data Source
AI summary
Implementations of the present disclosure generally relate to an improved lamphead assembly for use in a thermal processing chamber. In one implementation, a lamphead assembly comprises a lamp housing tube comprising a lamp disposed therein, the lamp housing tube having an open end facing towards the substrate support, and an insert tube disposed within the lamp housing tube, the insert tube surrounds at least a portion of the lamp and has a constant inner diameter throughout the entire length of the insert tube, wherein the insert tube collimates radiant energy from the lamp toward the substrate support. The insert tube comprises a cylindrical lower portion disposed adjacent to the open end of the lamp housing tube, and a tapered upper portion integrated with the cylindrical lower portion as one body.