Electrostatic Chuck Voltage Sequencing for Bowed Wafer Handling
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Solution Overview
Problem
In semiconductor processing, the evolution of chip designs leads to increased substrate bow and the need for higher electrostatic chucking voltage, which can cause DC plasma discharge and damage the substrate, while modified pedestal surfaces with posts can result in backside damage and lithographic defocus, impacting production yield.
Innovation Solution
A method involving the application of a direct current to an electrode in a pedestal, followed by the introduction of process gases and RF power to control substrate positioning and prevent damage, including specific voltage and power level adjustments to manage electrostatic chucking and plasma generation, ensuring stable substrate handling and processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If higher electrostatic chucking voltage is applied to clamp the substrate to the pedestal surface, then the substrate holding force is improved, but DC plasma discharge may occur adjacent to the substrate causing damage
Solution Approach 1:
The method applies electrostatic chucking voltage to the pedestal electrode before introducing process gases and applying RF power. This preliminary chucking action secures the substrate in position before processing begins, preventing substrate movement that could lead to plasma discharge damage while maintaining the necessary holding force throughout the process
Solution Approach 2:
The method dynamically adjusts the timing of voltage application by maintaining electrostatic chucking voltage throughout the entire process sequence - from gas introduction through RF processing to gas removal. This continuous dynamic application ensures the substrate remains securely clamped without releasing and risking plasma discharge, while allowing the system to adapt to different process conditions
2Manufacturing precision
If modified pedestal surface with posts is used to provide repeatable contact, then particle defects on substrate backside are minimized, but substrate can become damaged or break
Solution Approach 1:
The method applies electrostatic chucking voltage before introducing process gases, which secures the substrate to the pedestal surface in advance. This preliminary securing action prevents the substrate from moving or shifting during subsequent processing steps, thereby preventing damage at the contact posts while maintaining repeatable contact for minimizing particle defects
Solution Approach 2:
The electrostatic field acts as an intermediary force between the substrate and the pedestal posts. Instead of relying solely on mechanical contact at discrete post locations (which can cause damage), the electrostatic field distributes the holding force across the entire substrate surface, reducing localized stress at the posts while maintaining precise positioning
3Productivity
If substrate position is not adequately controlled during processing, then processing efficiency is maintained, but lithographic defocus occurs due to backside damage
Solution Approach 1:
The substrate is secured to the pedestal via electrostatic chucking before process gases are introduced and before RF power is applied. This preliminary positioning ensures the substrate is firmly held in the correct position from the start of processing, preventing movement that could cause lithographic defocus while maintaining continuous processing efficiency
Solution Approach 2:
The method implements a controlled sequence where electrostatic chucking voltage is applied first to establish substrate positioning, then process gases and RF power are introduced. This feedback-controlled sequencing ensures the substrate remains properly positioned throughout processing, preventing defocus while maintaining productivity
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 method reduces substrate damage, minimizes lithographic defocus, and enhances production yield by controlling substrate movement and thermal expansion, while maintaining effective electrostatic chucking and RF plasma generation.
Implementation Method 1
The chucking force is a function of the potential between a DC voltage provided to a chucking electrode embedded in a dielectric material of the pedestal and a substrate disposed on a surface of the dielectric material
Implementation Method 2
applying radio frequency (RF) power to a showerhead within the process chamber
Data Source
AI summary
One or more embodiments described herein generally relate to methods for chucking and de-chucking a substrate to/from an electrostatic chuck used in a semiconductor processing system. Generally, in embodiments described herein, the method includes: (1) applying a first voltage from a direct current (DC) power source to an electrode disposed within a pedestal; (2) introducing process gases into a process chamber; (3) applying power from a radio frequency (RF) power source to a showerhead; (4) performing a process on the substrate; (5) stopping application of the RF power; (6) removing the process gases from the process chamber; and (7) stopping applying the DC power.