Rotating Wafer Platform for PECVD Film Thickness Uniformity
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Solution Overview
Problem
The existing PECVD machines with twin chambers suffer from uneven film thickness distribution due to RF overlap, resulting in thicker films near the junction and thinner films at the edges, leading to inconsistent deposition rates and quality issues.
Innovation Solution
Incorporating speed-controlled rotating wafer heating platforms in the twin chambers, which rotate for integral rounds during deposition to ensure uniform RF overlap influence on inner and outer rings of wafers, compensating for thinner edge regions and improving film thickness uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If twin chambers are used to improve PECVD production capacity, then productivity increases, but film thickness uniformity deteriorates due to RF overlap near the junction
Solution Approach 1:
The patent introduces a rotating wafer heating platform that rotates during deposition. This dynamic motion distributes the RF overlap effect uniformly across the entire wafer surface over one complete rotation cycle, transforming a static non-uniform deposition problem into a dynamic uniform deposition process. The rotation ensures that each location on the wafer experiences the same integrated RF overlap influence, achieving uniform film thickness while maintaining twin-chamber productivity.
2Productivity
If RF generators are activated in both chambers, then deposition rate increases, but plasma density becomes uneven near the junction due to RF overlap
Solution Approach 1:
The rotating wafer heating platform dynamically distributes the plasma exposure and RF overlap effects uniformly across the wafer surface. During one complete rotation, every location on the wafer passes through the same plasma density zones, ensuring uniform cumulative exposure despite instantaneous non-uniformity. This maintains stable and uniform plasma density distribution while allowing both RF generators to operate at high power for increased deposition rate.
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 significantly reduces film thickness variations, achieving more even film distribution across the wafer surface, enhancing deposition uniformity and quality by over 51% compared to traditional methods.
Implementation Method 1
turning on RF generators 14 and 24, gas molecules are ionized to produce plasmas
Implementation Method 2
PECVD (Plasma Enhanced Chemical Vapor Deposition) ionizes gases containing film atoms by microwave or RF (Radio Frequency) to form plasma locally
Implementation Method 3
the speed controlled rotating platform is rotated for integral rounds during deposition time, in order to ensure same influence of a radio frequency overlap produced by the two radio frequency generators to inner rings and outer rings of wafers
Implementation Method 4
the plasmas with high chemical activity react on surface of wafers 12 and 22 on wafer heating platforms 11 and 21 to form films with required composition
Data Source
AI summary
The present disclosure relates to an apparatus and a method for improving film thickness uniformity, wherein a PECVD machine with twin chambers comprise a wafer heating platform, which is set to be a rotating platform with programmable speed control, by setting rotating speed of the platform, wafer is rotated for integral rounds within process time, so that a RF overlap between the twin chambers make consistent influence on edge regions of the wafer, and film around the wafer is evenly distributed, which not only eliminate abrupt change of film thickness caused by the RF overlap, but also reduce film thickness differences between edge regions and central regions of the film by a characteristic that the RF overlap improves film deposition rate, so as to ensure the film thickness more evenly in the range of the whole wafer.