Substrate Support Gap Pumping to Prevent Glow Discharge
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Solution Overview
Problem
Substrate processing systems face issues with glow discharge and light-up in gaps or cavities of substrate supports when exposed to plasma or high electric fields, which can lead to inefficiencies and potential damage.
Innovation Solution
The implementation of substrate supports with dedicated vacuum lines and pumps to specifically pump down gaps and cavities between substrate lift pins and their openings, maintaining lower pressures in these areas than in the processing volume, thereby preventing glow discharge and light-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If substrate supports have gaps or cavities in the substrate support structure, then the substrate support can accommodate lift pins and cooling channels, but glow discharge and light-up occur when exposed to plasma or high electric fields
Solution Approach 1:
The substrate support structure is divided into separate pressure zones: the processing chamber maintains process pressure while gaps and cavities within the substrate support are evacuated to vacuum pressure. This segmentation allows the support to have internal passages and lift pins while preventing glow discharge by maintaining vacuum in these internal spaces.
Solution Approach 2:
The gaps and cavities within the substrate support are evacuated to create a vacuum (inert) environment that prevents glow discharge and light-up when exposed to plasma or high electric fields. The vacuum lines continuously maintain this inert condition during processing.
2Reliability
If vacuum lines are added to pump down gaps and cavities, then glow discharge is prevented, but device complexity increases
Solution Approach 1:
The substrate support structure integrates multiple functions: it provides mechanical support for the substrate, contains cooling channels, accommodates lift pins for substrate positioning, and incorporates vacuum lines for pressure control. This multi-functionality justifies the added complexity by consolidating several systems into one component.
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 solution effectively prevents gas breakdown in substrate support gaps, minimizing backflow of process chemistry and maintaining process integrity by maintaining lower pressures in the substrate support gaps compared to the processing volume.
Implementation Method 1
vacuum lines that extend from the plurality of substrate lift pin openings and that are configured to pump down the plurality of substrate lift pin openings
Implementation Method 2
gaps or cavities in the substrate support that is not under vacuum pressure may be prone to glow discharge and light-up if exposed to plasma or if sufficiently high local electric field is present
Data Source
AI summary
Embodiments of substrate supports for use in substrate processing chambers are provided herein. In some embodiments, a substrate support for use in a substrate processing chamber includes: a pedestal having a first side configured to support a substrate and a second side opposite the first side; a plurality of substrate lift pins extending through the pedestal, wherein a plurality of first gaps are disposed between the plurality of substrate lift pins and respective ones of a plurality of substrate lift pin openings in the pedestal; and vacuum lines that extend from the plurality of substrate lift pin openings and that are configured to pump down the plurality of substrate lift pin openings.