Wafer Guide Height Tuning for Uniform Vapor Phase Growth
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Solution Overview
Problem
The uniformity of film thickness on a wafer is compromised due to the reduced flow rate of material gas at the outer edge of the wafer when the wafer guide is positioned too high, leading to thinner film deposition in the radial direction.
Innovation Solution
The wafer guide is positioned with its upward-facing surface located below the wafer surface by 0.65 mm or less, ensuring a consistent flow of material gas across the wafer surface, thereby maintaining uniform film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wafer guide is positioned with its upper surface excessively high, then the wafer is prevented from falling off the susceptor, but the flow rate of material gas to the outer edge of the wafer decreases causing non-uniform film thickness
Solution Approach 1:
The patent applies parameter changes by precisely controlling the height position of the wafer guide's upper surface relative to the wafer front surface. The specific parameter range is set to 0.5 mm to 2.0 mm above the wafer front surface, which optimizes both wafer retention and material gas flow distribution. This parameter optimization resolves the contradiction by finding the optimal height that prevents wafer fall-off while maintaining sufficient material gas flow to the wafer outer edge for uniform film deposition.
2Reliability
If the wafer guide position is adjusted to improve wafer retention, then the risk of wafer fall-off is reduced, but the deposition rate uniformity across the wafer surface deteriorates
Solution Approach 1:
The patent resolves this contradiction through parameter changes by establishing a specific height range (0.5-2.0 mm) for the wafer guide upper surface. This controlled parameter adjustment ensures that the wafer guide provides sufficient support to prevent wafer fall-off during rotation, while simultaneously maintaining adequate material gas flow access to the wafer outer edge, thereby preserving uniform deposition rates across the entire wafer surface.
3Stability of the object's composition
If the wafer guide is positioned higher to secure the wafer, then mechanical stability is improved, but the material gas flow distribution becomes non-uniform
Solution Approach 1:
The patent applies parameter changes by optimizing the vertical position of the wafer guide within the specific range of 0.5 mm to 2.0 mm above the wafer front surface. This optimized parameter setting provides sufficient mechanical support to stabilize wafer positioning and prevent fall-off during rotation, while simultaneously ensuring that material gas can flow uniformly across the wafer surface, including adequate supply to the outer edge regions.
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 enhances the uniformity of film thickness by reducing the variation in deposition rates across the wafer surface, allowing for more consistent film deposition and minimizing the need for frequent wafer guide replacements.
Implementation Method 1
Vapor phase growth apparatus, in which the uniformity of the thickness of a film is improved by depositing a SiC film or the like on a front surface of a wafer while a susceptor having the wafer mounted thereon is rotated
Data Source
AI summary
A vapor phase growth apparatus of an embodiment has a susceptor configured to allow a wafer to be mounted thereon, a drive unit configured to rotate the susceptor, and a wafer guide having a ring shape to surround an outer edge of the wafer and being attached to the susceptor. An upward facing surface of the wafer guide is located below a level which is located 0.65 mm above an upward facing surface of the wafer.