Electrostatic Chuck Support Features for Substrate Backside Damage
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Solution Overview
Problem
Existing electrostatic chucks cause backside puncture and scratch damage to semiconductor substrates due to electrostatic forces and thermal expansion, leading to lithographic defocus and reduced production yield.
Innovation Solution
A substrate support with a body containing an electrode and temperature control device, featuring a plurality of substrate supporting features with rounded edges, and a method involving a plasma or non-plasma preheat treatment followed by electrostatic chucking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrostatic forces are applied to hold the substrate against the electrostatic chuck, then the substrate is securely held during processing, but backside puncture damage occurs to the substrate
Solution Approach 1:
The substrate support surface is segmented into multiple discrete substrate supporting features (protrusions or projections) rather than a continuous flat surface. These features are distributed across the substrate backside, providing localized support points that reduce the concentrated electrostatic force density, thereby preventing puncture damage while maintaining overall substrate holding stability.
Solution Approach 2:
The substrate supporting features have locally optimized properties including specific height ranges (0.1mm to 3mm), diameter ranges (0.05mm to 2mm), and spacing arrangements that create optimal electrostatic field distribution. The rounded edges at the tips of these features further localize the stress distribution, preventing puncture while maintaining secure holding.
2Temperature
If high processing temperatures are applied, then the substrate undergoes necessary thermal processing, but thermal expansion causes sliding of the substrate backside along the electrostatic chuck, resulting in backside scratch damage
Solution Approach 1:
A preheat treatment is performed before the main processing step to gradually thermal expand the substrate. This preliminary heating at controlled rates (e.g., 10°C/min to 50°C/min) allows the substrate to expand in a controlled manner, reducing thermal shock and minimizing relative sliding between the substrate backside and the electrostatic chuck surface during subsequent high-temperature processing.
Solution Approach 2:
The substrate supporting features are designed with rounded edges and curved surfaces rather than sharp corners or flat surfaces. This curvature distributes the contact stress more evenly during substrate thermal expansion and sliding, preventing concentrated stress points that would cause scratch damage while still maintaining effective substrate holding.
3Reliability
If substrate supporting features with sharp edges are used, then the substrate is firmly held, but scratch damage occurs on the substrate backside
Solution Approach 1:
The substrate supporting features are specifically designed with rounded edges having radii of curvature in the range of 1μm to 100μm. This curvature allows the features to firmly hold the substrate through electrostatic forces distributed over a larger contact area, eliminating the stress concentration that would occur with sharp edges and thereby preventing scratch damage during substrate processing.
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
The solution significantly reduces backside damage to substrates during processing, improving lithography process yield by 30-80% and lowering operational costs associated with integrated circuit manufacturing.
Implementation Method 1
exposing the substrate to a plasma preheat treatment. The plasma preheat treatment includes flowing one or more inert gases into a process volume, generating a plasma from the inert gases, and maintaining the plasma in the process volume
Implementation Method 2
the backside of a substrate, such as a semiconductor substrate, is held to the face of the electrostatic chuck by electrostatic forces that are generated from one or more electrodes embedded in the electrostatic chuck
Implementation Method 3
thermal expansion of the substrate during high processing temperatures can result in sliding of the backside of the substrate along the electrostatic chuck
Data Source
AI summary
Embodiments of the present disclosure generally relate to apparatus and methods for reducing substrate backside damage during semiconductor device processing. In one implementation, a method of chucking a substrate in a substrate process chamber includes exposing the substrate to a plasma preheat treatment prior to applying a chucking voltage to a substrate support. In one implementation, a substrate support is provided and includes a body having an electrode and thermal control device disposed therein. A plurality of substrate supporting features are formed on an upper surface of the body, each of the substrate supporting features having a substrate supporting surface and a rounded edge.