Substrate Support Pin Impedance Control for Uniform PECVD Deposition
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Solution Overview
Problem
Non-uniform deposition on substrates due to substrate support pins leads to sub-optimal film thickness and 'mura effect' in plasma-enhanced chemical vapor deposition processes, affecting semiconductor device yield and performance.
Innovation Solution
A plasma processing system with adjustable impedance circuits and RF voltage/current detectors to control local impedance at substrate support pins, ensuring uniform film deposition by dynamically adjusting impedance to match bulk plasma chamber impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If substrate support pins are used to support the substrate during transfer and processing, then substrate transfer and positioning are enabled, but non-uniform film deposition occurs at pin locations causing mura effect
Solution Approach 1:
The patent applies local quality by making each substrate support pin independently controllable through individual RF impedance matching circuits. Each pin can be adjusted to have different electrical characteristics to compensate for local deposition variations, thereby achieving uniform film thickness across the entire substrate while maintaining the mechanical support function of the pins
Solution Approach 2:
The patent changes the electrical parameter (RF impedance) of each substrate support pin dynamically during the deposition process. By adjusting the RF impedance matching circuits, the electrical potential distribution is optimized to ensure uniform plasma deposition across the substrate, resolving the contradiction between using physical support pins and achieving uniform film thickness
2Stability of the object's composition
If multiple substrate support pins are used to hold the substrate, then substrate positioning stability is improved, but deposition uniformity deteriorates due to shadowing and electrical interference
Solution Approach 1:
The patent dynamically adjusts the RF impedance parameter of each support pin during deposition to compensate for shadowing effects and electrical interference. By independently controlling the electrical potential of each pin, uniform plasma distribution is achieved while maintaining stable substrate positioning through the multiple pins
Solution Approach 2:
The patent implements a feedback control system where deposition uniformity is monitored and used to adjust the RF impedance of individual support pins in real-time. This feedback mechanism allows the system to compensate for positioning-related deposition variations, maintaining both stable positioning and uniform deposition
3Ease of operation
If substrate support pins extend above the substrate support surface, then substrate transfer mechanism access is facilitated, but film deposition quality deteriorates at pin locations
Solution Approach 1:
The patent changes the electrical parameter (RF impedance) of support pins that extend above the surface to compensate for their impact on deposition. By adjusting the impedance of these specific pins, the system maintains the mechanical advantage of extended pins for transfer access while eliminating their negative impact on film deposition quality through electrical field optimization
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
Achieves uniform film thickness and minimizes 'mura effect' by maintaining consistent film properties across the substrate, enhancing deposition process yields and panel utilization.
Implementation Method 1
each of the plurality of substrate support pins is individually adjustable to control radio frequency electrical impedance at a respective location of each of the plurality of substrate support pins
Implementation Method 2
plasma-enhanced chemical vapor deposition (PECVD) is a process where films may be deposited onto a substrate
Implementation Method 3
process uniformity and repeatability within a chamber, from chamber to chamber and processing system to processing system are parameters for controlling semiconductor device yield
Data Source
AI summary
Embodiments of the present disclosure generally relate to methods and apparatus for measuring and controlling local impedances at a substrate support in a plasma processing chamber during processing of a substrate. A substrate support includes a plurality of substrate support pins wherein the radio frequency voltage, current and phase of each of the plurality of substrate support pins are measured and impedances of the support pins are adjusted in real time. Each of the substrate support pins is coupled to an associated adjustable impedance circuit that may be remotely controlled. In one embodiment a variable capacitor is used to adjust the impedance of the impedance circuit coupled to the associated substrate support pin and may be remotely adjusted with a stepper motor. In another embodiment a microcontroller may control the impedance adjustments for all of the plurality of substrate support pins and may be used to track these impedances with each other and with a bulk impedance of the plasma processing chamber.