PVD Substrate Clamp with Insulator for Uniform RF Current
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Solution Overview
Problem
RF physical vapor deposition methods face challenges in achieving uniform temperature and RF current distribution across substrates, leading to nonuniform deposited films due to temperature nonuniformity and RF current spikes.
Innovation Solution
Incorporating a graphite heat diffuser with passages for improved heat transfer and using an insulator or conductive spring systems to isolate the substrate from the clamp, ensuring uniform temperature and controlled RF current distribution, which can form films with specific crystalline structures like (111) or (100) orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the substrate is directly clamped to the chuck without insulation, then the RF current distribution becomes nonuniform with spikes at contact points, but adding an insulator between the substrate and clamp improves RF current distribution uniformity
Solution Approach 1:
An insulator (such as a ceramic or quartz ring) is introduced as an intermediary component between the conductive clamp and the substrate. This insulator prevents direct electrical contact, eliminating RF current spikes at contact points while still allowing mechanical clamping force to be applied. The insulator acts as a mediator that decouples the electrical and mechanical functions, improving RF current distribution uniformity across the substrate surface.
2Manufacturing precision
If the substrate is heated to high temperature for film deposition, then the film quality improves, but temperature nonuniformity across the substrate increases
Solution Approach 1:
A heat diffuser made of thermally conductive material (such as graphite or metal) is introduced as an intermediary layer between the heating chuck and the substrate. This heat diffuser receives heat from the chuck and redistributes it uniformly across its surface, then transfers the uniform heat to the substrate. The heat diffuser acts as a thermal mediator that decouples the heating source from the substrate, enabling high temperature deposition while maintaining temperature uniformity across the substrate surface.
3Ease of operation
If a conductive clamp is used to hold the substrate, then the clamp provides good electrical contact, but it causes RF current spikes at the contact points
Solution Approach 1:
An insulator is introduced as an intermediary component between the conductive clamp and the substrate. This insulator prevents direct electrical contact between the clamp and substrate, eliminating RF current spikes at contact points. The insulator allows the clamp to maintain mechanical holding function while blocking harmful electrical contact, thus resolving the contradiction between ease of operation and manufacturing precision.
4Reliability
If the clamp is electrically isolated from the chamber walls, then the RF plasma discharge is improved, but the clamp cannot be used for electrical grounding
Solution Approach 1:
The clamp system is segmented into separate functional components: a conductive clamp portion for mechanical holding and an insulator portion for electrical isolation. The insulator (such as a ceramic or quartz ring) electrically isolates the clamp from the chamber walls, improving plasma discharge stability. Meanwhile, the conductive clamp portion can still be independently connected to ground if needed, providing adaptability. This segmentation allows both plasma discharge stability and electrical grounding capability to coexist.
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 solutions result in more uniform physical characteristics of the deposited films, with improved temperature uniformity and RF current distribution, achieving films with advantageous dielectric and piezoelectric properties such as high d33 or d31 coefficients and breakdown voltages.
Implementation Method 1
Radio frequency sputtering PVD is a method for depositing a thin film on a substrate. The substrate is placed in a vacuum chamber facing a target that is connected to an RF power supply. When the RF power is initiated, a plasma is formed. Positive gas ions are pulled to the target surface, strike the target, and remove target atoms by momentum transfer. The removed target atoms then deposit on the substrate to form a thin film layer.
Implementation Method 2
a heater to heat the substrate supported on the chuck
Implementation Method 3
Incorporating a graphite heat diffuser with passages for improved heat transfer and using an insulator or conductive spring systems to isolate the substrate from the clamp, ensuring uniform temperature
Data Source
AI summary
A physical vapor deposition apparatus includes a vacuum chamber having side walls, a cathode inside the vacuum chamber, wherein the cathode is configured to include a sputtering target, a radio frequency power supply configured to apply power to the cathode, an anode inside and electrically connected to the side walls of the vacuum chamber, a chuck inside and electrically isolated from the side walls of the vacuum chamber, the chuck configured to support a substrate, a clamp configured to hold the substrate to the chuck, wherein the clamp is electrically conductive, and a plurality of conductive electrodes attached to the clamp, each electrode configured to compress when contacted by the substrate.