Electrostatic Chuck Seal Surface for Backside Deposition Control
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Solution Overview
Problem
Existing semiconductor processing systems face challenges in preventing backside deposition on substrates during processing, leading to alignment issues and increased time for recalibration in lithography.
Innovation Solution
The system incorporates a pedestal with an upper annular seal surface and micro-contact areas (MCAs) to support the substrate, along with electrostatic clamp electrodes that provide an electrostatic clamping force to prevent gas flow to the backside of the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional pedestal without seal surface is used, then the structure is simple, but backside deposition occurs on the substrate
Solution Approach 1:
The pedestal surface is segmented into multiple functional zones: an upper annular seal surface for creating the seal, a lower recess surface for electrostatic clamping, and micro-contact areas for substrate support. This segmentation allows each zone to perform its specific function independently, preventing backside deposition while maintaining substrate stability.
Solution Approach 2:
The upper annular seal surface acts as an intermediary element between the pedestal and the substrate edge. It creates a seal that prevents process gas from reaching the substrate backside, thereby eliminating backside deposition without requiring direct contact between the substrate and the entire pedestal surface.
2Object-affected harmful factors
If electrostatic clamping force is applied to prevent backside deposition, then deposition is reduced, but substrate centering becomes critical
Solution Approach 1:
The substrate is preliminarily positioned and centered on the pedestal before electrostatic clamping is fully engaged. The upper annular seal surface and micro-contact areas provide initial mechanical support and alignment, ensuring the substrate is properly centered before the electrostatic force creates the seal.
Solution Approach 2:
Different regions of the pedestal provide different functions: the upper annular seal surface provides sealing at the substrate edge, the micro-contact areas provide localized support points for centering, and the lower recess surface provides electrostatic clamping. This local differentiation of functions ensures both centering precision and effective seal creation.
3Object-affected harmful factors
If the seal surface is made larger to improve sealing, then backside deposition is prevented, but the pedestal height increases
Solution Approach 1:
Instead of increasing the seal surface area in the horizontal plane, the solution uses the vertical dimension by creating an upper annular seal surface that extends radially outward from the center. This annular configuration provides sufficient sealing length without increasing overall pedestal height, as the seal is formed by the radial thickness of the annular surface rather than its axial height.
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 configuration effectively reduces backside deposition by creating a seal between the substrate and the upper annular seal surface, improving substrate centering and reducing unwanted deposition on the backside.
Implementation Method 1
one or more electrostatic clamp electrodes within the body... configured to provide an electrostatic clamping force on the semiconductor substrate
Implementation Method 2
a seal is created between the upper annular seal surface and the semiconductor substrate when the one or more electrostatic clamp electrodes provide the electrostatic clamping force
Data Source
AI summary
Apparatuses and systems for pedestals are provided. An example pedestal may have a body with an upper annular seal surface that is planar, perpendicular to a vertical center axis of the body, and has a radial thickness, a lower recess surface offset from the upper annular seal surface, and a plurality of micro-contact areas (MCAs) protruding from the lower recess surface, each MCA having a top surface offset from the lower recess surface by a second distance less, and one or more electrodes within the body. The upper annular seal surface may be configured to support an outer edge of a semiconductor substrate when the semiconductor substrate is being supported by the pedestal, and the upper annular seal surface and the tops of the MCAs may be configured to support the semiconductor substrate when the semiconductor substrate is being supported by the pedestal.