Heated Stoppers for Uniform SOI Film Thickness
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Solution Overview
Problem
In the manufacturing of SIMOX semiconductor substrates, the existing ion implantation apparatuses face challenges in achieving uniform film thickness of the SOI and BOX layers due to temperature drops caused by heat conduction and radiation heat transfer at the contact points with stoppers, leading to non-uniformity in film thickness.
Innovation Solution
The apparatus incorporates a heating unit integrated into the stoppers made of conductive materials, which are supported by strong metallic holders and can be heated independently to maintain temperature uniformity during ion implantation, ensuring consistent film thickness across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stoppers are used to prevent semiconductor substrates from flying off during high-speed rotation, then substrate holding reliability is improved, but temperature uniformity deteriorates due to heat conduction and radiation heat transfer at contact points
Solution Approach 1:
The stopper is designed with different thermal properties at different locations: the contact surface with the substrate uses a material with low thermal conductivity (such as ceramic or plastic) to minimize heat conduction, while the structural body maintains mechanical strength. This local differentiation of material properties allows the stopper to prevent substrate fly-off while reducing harmful heat transfer at the contact point, thereby maintaining temperature uniformity during ion implantation.
2Reliability
If support disks are rotated at high speed to provide centrifugal force for substrate support, then substrate positioning is improved, but heat loss through stoppers increases due to higher acceleration forces
Solution Approach 1:
The stopper structure implements local quality by using low thermal conductivity materials specifically at the substrate contact region. This allows the stopper to effectively hold the substrate under high centrifugal force while minimizing heat conduction from the substrate to the stopper, thereby reducing energy loss even during high-speed rotation.
Solution Approach 2:
An intermediate layer or coating with low thermal conductivity is introduced between the substrate and the stopper. This intermediary layer acts as a thermal barrier that prevents direct heat transfer while still allowing mechanical contact for substrate holding, thus reducing heat loss during high-speed rotation without compromising positioning reliability.
3Reliability
If conventional stoppers made of conductive materials are used to ensure current passage, then electrical conductivity is improved, but temperature uniformity deteriorates due to increased heat conduction
Solution Approach 1:
The stopper is designed with spatially varying material properties: the contact surface with the substrate is made of low thermal conductivity material to minimize heat conduction, while separate conductive elements or pathways are provided to ensure current passage. This local differentiation allows the system to maintain both electrical conductivity and temperature uniformity simultaneously.
Solution Approach 2:
The stopper structure is segmented into functionally distinct regions: one part responsible for mechanical holding with low thermal conductivity material, and another part or pathway dedicated to electrical conduction. This segmentation allows each function to be optimized independently, ensuring current passage without compromising 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
The implementation of heating units in the stoppers enhances temperature uniformity and improves the uniformity of the SOI and BOX layers by compensating for heat loss, resulting in more consistent film thickness across the substrate.
Implementation Method 1
The stopper is formed of a conductive material and has a heating unit which heats the stopper
Implementation Method 2
Centrifugal force is utilized for the support of semiconductor substrates
Implementation Method 3
heat generated in the semiconductor substrates due to ion implantation is put out through the support disks by radiation heat transfer from the entire rear face of the semiconductor substrates
Data Source
AI summary
This apparatus for manufacturing semiconductor substrates has support disks and holding units holding semiconductor substrates on the support disks. The holding unit has a stopper which is formed of a conductive material and holds the brim of the semiconductor substrate, a stopper holder which supports the stopper at the outer circumferential portion thereof, a retaining member which retains the stopper to the support disk, and a heating unit which heats the stopper.