Spatial ALD Substrate Support Assembly for Low-Travel Transfer
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Solution Overview
Problem
Current spatial ALD processing chambers face issues with non-uniform plasma exposure, plasma damage, and limited Z-axis travel, which affect throughput and lead to premature failure of lift pins due to high acceleration forces, and require optimization for efficient substrate loading and unloading.
Innovation Solution
The implementation of a support assembly with rotatable center base, support arms, and lift pins that allow for precise movement and alignment within the processing chamber, enabling efficient substrate loading and unloading without the need for extensive Z-axis travel, and using conductive materials to prevent charge buildup and ensure safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If substrates are rotated at constant speed in spatial ALD chamber, then substrates move through processing environments, but plasma exposure becomes non-uniform and causes plasma damage
Solution Approach 1:
The patent applies dynamics by making the rotation speed variable rather than constant. The controller adjusts rotation speed dynamically based on substrate position: slower through plasma regions for uniform exposure, faster through non-plasma regions to maintain throughput. This resolves the contradiction between maintaining constant throughput and achieving uniform plasma exposure.
2Ease of operation
If lift pins are used for substrate loading and unloading, then substrate transfer is enabled, but lift pins fail prematurely due to high acceleration forces
Solution Approach 1:
The patent applies counterweight by adding weights to the lift pins to balance the centrifugal forces generated during high-speed rotation. This compensation reduces the net acceleration forces acting on the lift pins, preventing premature failure while maintaining the ability to rapidly load and unload substrates.
3Volume of stationary object
If chamber Z-axis travel is limited to maximum space, then physical space constraints are satisfied, but substrate loading and unloading becomes difficult
Solution Approach 1:
The patent applies dimensionality change by using radial movement (rotating the substrate holder to bring substrates closer to access ports) combined with minimal axial movement. This allows substrate loading/unloading in a compact Z-direction while maintaining ease of access through operational sequencing in the radial dimension.
4Manufacturing precision
If rotation speed is adjusted to optimize plasma exposure, then plasma uniformity improves, but throughput decreases
Solution Approach 1:
The patent applies periodic action by varying rotation speed periodically according to substrate position. The controller implements a speed profile that slows rotation when substrates enter plasma regions and accelerates when exiting, creating a rhythmic pattern of speed adjustment that maintains both uniform exposure and high throughput.
5Speed
If lift pins are subjected to high acceleration forces for rapid substrate transfer, then throughput increases, but lift pins experience premature failure
Solution Approach 1:
The patent uses counterweights on lift pins to offset the high acceleration forces during rapid substrate transfer. This allows the system to maintain high transfer speeds for improved throughput while the counterweights prevent excessive stress on the lift pins, extending their service life.
Data Source
AI summary
Apparatus and methods for loading and unloading substrates from a spatial processing chamber are described. A support assembly has a rotatable center base and support arms extending therefrom. A support shaft is at the outer end of the support arms and a substrate support is on the support shaft. Primary lift pins are positioned within openings in the substrate support. Secondary lift pins are positioned within openings in the support arms and are aligned with the primary lift pins. An actuation plate within the processing volume causes, upon movement of the support assembly, the primary lift pins to elevate through contact with the secondary lift pins.