CVD Chamber Window Profile for Wafer Uniformity
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Solution Overview
Problem
Achieving uniform layer thickness in semiconductor wafers deposited via CVD is challenging due to variations in deposition rates across the wafer, particularly at the edge regions, leading to non-uniformity issues.
Innovation Solution
A CVD chamber design with a window configuration where the distance between the semiconductor wafer and the transmissive window varies, with a smaller distance at the center and a larger distance at the edge, and a radial profile angle of 15° to 25° at the boundary, allowing for a non-uniform gas flow speed to mitigate edge effects and enhance uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional CVD chamber with a flat window is used, then the structure is simple, but the layer thickness uniformity deteriorates due to edge effects
Solution Approach 1:
The window is designed with a radial distance profile where the distance from the window to the wafer plane varies continuously: smaller at the center and larger at the edges. This local variation in geometry creates different gas flow characteristics and deposition rates at different radial positions, compensating for edge effects and achieving uniform layer thickness across the wafer surface.
2Manufacturing precision
If the distance between window and wafer is uniform, then the chamber structure is simple, but the deposition rate varies across the wafer surface
Solution Approach 1:
The window geometry is designed with a specific radial distance profile parameter, where the distance from the window to the wafer plane changes continuously from center to edge. The tangent angle at the boundary between center and edge regions is controlled within 15° to 25°, optimizing the gas flow and deposition characteristics to achieve uniform layer thickness while managing fabrication complexity.
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 design significantly reduces layer thickness variation, as demonstrated by lower R parameter values, indicating improved uniformity across the wafer surface.
Implementation Method 1
a window that is transmissive to thermal radiation
Implementation Method 2
Method for depositing a layer on a semiconductor wafer by means of CVD ('chemical vapor deposition')
Data Source
AI summary
A method for depositing a layer on a semiconductor wafer using chemical vapor deposition (CVD). The method includes providing a chamber having an inlet opening and an outlet opening and a channel joining the inlet opening and the outlet opening, wherein the channel is bounded at the bottom by a plane and at the top by a window transmissive to thermal radiation. A semiconductor wafer is disposed so that a surface of the semiconductor lies in the plane, wherein the window has a center region disposed over the semiconductor wafer and an edge region surrounding the center region and not disposed over the semiconductor wafer. A distance between the plane and the window varies across the chamber, the distance being greater at the edge region than at the center region. A tangent applied to a radial profile of the distance at a boundary between the center region and the edge region forms an angle with the plane of not less than 15° and not more than 25°. A deposition gas is conducted through the channel from the gas inlet opening over the semiconductor wafer to the gas outlet opening, wherein a speed at which the deposition gas is conducted varies over the semiconductor wafer according to the varying distance between the plane and the window.