Wafer Bow Modulation in PECVD for Uniform Thin Film Growth
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Solution Overview
Problem
Conventional semiconductor substrate processing systems face challenges with high wafer bow, leading to inconsistent thin film deposition due to variations from wafer to wafer, station to station, and batch to batch, and electrostatic clamping has not been successful in eliminating these variations.
Innovation Solution
The method involves modulating film growth by controlling the wafer bow through a multi-phase deposition process, where the wafer is clamped during the first deposition phase and unclamped during the second phase, or vice versa, allowing for a non-zero wafer bow to be induced or changed, thereby achieving a more consistent thin film thickness profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If electrostatic clamping is used to reduce wafer bow, then wafer flatness is improved, but manufacturing precision of thin film deposition deteriorates due to inconsistent wafer bow variations
Solution Approach 1:
The patent applies dynamics by transitioning the wafer clamping state from static (continuously clamped) to dynamic (switching between clamped and unclamped states during deposition). The wafer is clamped during the first deposition phase to achieve flatness, then unclamped during the second phase to allow controlled wafer bow development, which modulates film growth and improves thickness uniformity across the wafer surface.
Solution Approach 2:
The patent implements periodic action by dividing the deposition process into distinct phases with alternating clamping states. The wafer undergoes periodic transitions between clamped and unclamped conditions, creating different deposition environments in each phase that collectively produce a more uniform thin film thickness profile than continuous clamping alone.
2Shape
If wafer bow is reduced to zero using clamping, then wafer flatness is improved, but film growth modulation capability is lost
Solution Approach 1:
The patent restores adaptability by making the wafer clamping state dynamic rather than fixed. By switching between clamped and unclamped states during different deposition phases, the system can modulate film growth characteristics to achieve desired thickness profiles, combining the benefits of both flatness control and growth modulation capability.
3Device complexity
If single-phase deposition is used with clamped wafer, then process simplicity is maintained, but thin film thickness uniformity deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the deposition process into multiple phases with different clamping states. The first phase deposits a portion of the film with the wafer clamped, and the second phase deposits the remaining portion with the wafer unclamped, allowing each phase to contribute differently to the final thickness profile and improve overall 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
This approach results in a more consistent thin film deposition by varying the deposition thickness profile across the wafer, reducing strain and achieving a uniform thickness distribution compared to single-phase deposition methods.
Implementation Method 1
an electrostatic chuck (ESC) is used to reduce the wafer bow
Implementation Method 2
Radio frequency (RF) power is applied between the electrodes to excite a process gas into plasma for processing (for example, layer deposition) on a substrate
Implementation Method 3
plasma-enhanced chemical vapor deposition (PECVD)
Data Source
AI summary
A process chamber and method of modulating thin film growth on a wafer using a plasma-enhanced chemical vapor deposition (PECVD) process is described. During a first deposition phase, a first portion of a film is disposed on a wafer on a pedestal in a process chamber. During a second deposition phase, a second portion of the film is deposited on the wafer. The wafer is unclamped from the pedestal prior to the first and/or second deposition phase and remains unclamped during the first and/or second deposition phase. The wafer has a non-zero wafer bow during unclamped deposition phase to provide a radially non-uniform thickness profile of the film on the wafer.