Epitaxial Wafer Alignment After Chamber Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for producing semiconductor wafers with epitaxial layers face challenges in maintaining uniform thickness, particularly at the edge regions, due to misalignment of the substrate wafer on the susceptor during deposition, which leads to increased edge drop and particle formation from one coating process to another.
Innovation Solution
A method is introduced where the correction specification for the substrate wafer's placement on the susceptor is calculated by averaging the positional deviations of substrate disks that were the first to be coated after a chamber etching, specifically using positional deviations of at least 3 such disks to improve alignment and reduce thermal stress-induced misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a correction specification based on average positional deviation is used to improve substrate wafer alignment on the susceptor, then manufacturing precision of epitaxial layer thickness is improved, but the complexity of the deposition process increases due to additional calculation and adjustment steps
Solution Approach 1:
The correction specification is calculated in advance based on historical positional deviation data from previous coating processes. This preliminary calculation allows the robot to pre-adjust the placement position of substrate wafers, compensating for expected misalignment before deposition begins, thereby improving thickness uniformity without adding real-time complexity during the actual coating process
Solution Approach 2:
The correction specification is derived from feedback data collected from previous coating processes, specifically the average positional deviation of substrate wafer centers from the susceptor center. This feedback mechanism enables continuous improvement of alignment accuracy by learning from historical data, resolving the contradiction between precision improvement and process complexity
2Ease of operation
If the substrate wafer is positioned concentrically on the susceptor during deposition, then ease of operation is improved, but manufacturing precision deteriorates due to thermal stress-induced misalignment during the coating process
Solution Approach 1:
The correction specification applies a pre-calculated offset to the placement position that counteracts the expected thermal stress-induced misalignment. By positioning the substrate wafer slightly off-center initially, the system anticipates and compensates for the thermal drift that occurs during heating and deposition, maintaining manufacturing precision while keeping the operation simple
Solution Approach 2:
Instead of symmetric concentric positioning, the system deliberately introduces asymmetric placement by applying a correction offset based on historical deviation data. This asymmetric positioning strategy compensates for the asymmetric thermal stress effects during deposition, improving thickness uniformity without complicating the positioning operation
3Productivity
If chamber etching is performed to remove deposited material, then productivity is improved by enabling continuous coating processes, but manufacturing precision worsens due to increased edge drop in subsequent coating processes
Solution Approach 1:
After chamber etching, the system calculates a new correction specification based on positional deviation data from coating processes that occurred after previous etching events. This preliminary adjustment of the correction specification before subsequent coating ensures that the first substrate wafer positioned after etching is properly aligned, preventing edge drop and maintaining manufacturing precision while enabling continuous productivity
Solution Approach 2:
The system uses feedback from positional deviation measurements of substrate wafers coated after chamber etching to update the correction specification. This feedback loop ensures that the correction adapts to changes in chamber conditions following etching, maintaining edge geometry uniformity across continuous production cycles
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 approach enhances the uniformity of the epitaxial layer thickness and reduces particle formation by providing a more precise correction specification, improving the edge geometry and deposition process consistency.
Implementation Method 1
a deposition gas at a deposition temperature is passed through the deposition chamber over the substrate wafer
Implementation Method 2
an epitaxial layer deposited from the vapor phase in a deposition chamber
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for producing semiconductor wafers with an epitaxial layer deposited from the gas phase in a deposition chamber, comprising removing material from the deposition chamber that has accumulated in the deposition chamber during previous coating processes by etching the deposition chamber; successive coating processes carried out in the etched deposition chamber, each comprising depositing a substrate wafer onto a susceptor with a circular circumference by a robot, wherein the robot moves the substrate wafer into a deposit position and places it on the susceptor, wherein in the deposit position the center of the substrate wafer is not located above the center of the susceptor due to a correction specification;and the deposition of an epitaxial layer on the substrate disk, wherein a semiconductor disk with an epitaxial layer is formed, characterized in that for each first substrate disk which is moved by the robot to the deposit position after etching of the deposition chamber, the amount of the correction specification corresponds to an average value of positional deviations of a number of previously coated substrate disks, which themselves were each the first to be coated after a previous chamber etching.