Electrostatic Chuck Soft-Chucking for Backside Particle Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The sudden application of high voltage during substrate chucking and dechucking in plasma processes causes high force, leading to relative motion, particle generation, and damage due to thermal expansion mismatch between the substrate and electrostatic chuck, resulting in scratches and particle release on the backside of the substrate.
Innovation Solution
A two-stage soft chucking process is implemented, where a lower initial voltage is applied first to allow temperature stabilization, followed by a higher voltage application after temperature equilibration, accompanied by controlled gas pressure adjustments to minimize thermal stress and particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high voltage is applied suddenly to the chucking electrode to chuck the substrate, then the chucking force is sufficient to secure the substrate, but the sudden force causes relative motion between the substrate and electrostatic chuck surface, generating particles and causing scratches
Solution Approach 1:
The voltage application process is divided into multiple stages: an initial lower voltage stage followed by a higher voltage stage. This segmentation allows the substrate to be gradually secured to the electrostatic chuck without sudden force application, preventing relative motion and particle generation while still achieving sufficient chucking force.
Solution Approach 2:
A preliminary lower voltage is applied to the chucking electrode before the substrate fully contacts the electrostatic chuck surface. This preliminary action reduces the impact force when the substrate makes contact, preventing sudden relative motion and particle generation, while still providing initial securing force.
2Temperature
If the substrate temperature equilibrates to match the electrostatic chuck temperature, then thermal contact is improved, but the CTE mismatch causes relative motion between the substrate backside and chuck surface, generating particles and scratches
Solution Approach 1:
The temperature equilibration process is segmented into stages corresponding to voltage application stages. During the initial lower voltage stage, the substrate temperature begins to equilibrate with the electrostatic chuck. Once equilibration is achieved, the voltage is increased to the higher stage. This segmentation prevents relative motion during the critical thermal expansion phase while maintaining good thermal contact.
3Productivity
If a single high voltage is applied immediately during substrate chucking, then the chucking process is fast and efficient, but particle generation and substrate damage occur due to sudden force and thermal stress
Solution Approach 1:
The chucking process is divided into two voltage stages: an initial lower voltage stage that allows controlled substrate contact and thermal equilibration, followed by a higher voltage stage that completes the chucking. This segmentation reduces particle generation during the critical initial contact phase while maintaining overall process efficiency.
Solution Approach 2:
The voltage application follows a periodic pattern with distinct phases: initial lower voltage application, intermediate stabilization period allowing thermal equilibration, and subsequent higher voltage application. This periodic action prevents particle generation during thermal stress while maintaining productive chucking.
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
Reduces particle generation and substrate damage by minimizing thermal stress through controlled voltage and gas pressure stages, achieving a significant reduction in particles released from the substrate backside, with helium showing a 34% reduction and argon showing an 83% reduction compared to single-stage processes.
Implementation Method 1
a voltage from a direct current voltage source is applied from the voltage source to the chucking electrode so that the substrate is 'chucked' to a surface of the electrostatic chuck by a Coulombic or Johnson-Rahbek force generated from the voltage application
Implementation Method 2
a voltage from a direct current voltage source is applied from the voltage source to the chucking electrode so that the substrate is 'chucked' to a surface of the electrostatic chuck by a Coulombic or Johnson-Rahbek force generated from the voltage application
Implementation Method 3
as the temperature of the substrate equilibrates to match the temperature of the surface of the electrostatic chuck, the coefficient of thermal expansion (CTE) mismatch between the substrate and the surface of the electrostatic chuck causes relative motion
Data Source
AI summary
Embodiments of this disclosure include methods of chucking and de-chucking a substrate. A method of chucking a substrate to a surface of an electrostatic chuck includes applying a first voltage to a chucking electrode in the ESC during a chucking time interval, supplying an inert gas at a first pressure to a backside of the substrate during the chucking time interval, applying a second voltage to the chucking electrode in the ESC after the chucking time interval, the second voltage being higher than the first voltage, and supplying the inert gas at a second pressure to the backside of the substrate after the chucking time interval, the second pressure being higher than the first pressure of the inert gas.