Showerhead Divert Flow Path for ALD Dead Leg Reduction
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Solution Overview
Problem
Substrate processing systems face challenges in rapidly transitioning between gas cycles during atomic layer deposition (ALD) processes due to dead leg volumes in showerheads, leading to longer cycling times and non-uniform gas flow, which affects substrate uniformity.
Innovation Solution
The design incorporates a showerhead with an integral gas divert path downstream from the plenum, allowing gas to exit directly to the chamber exhaust, minimizing dead leg volume and enabling faster cycling and more uniform gas distribution by diverting gas flow away from the process volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gas is delivered through traditional gas flow channels in substrate processing systems, then the substrate can be processed with deposited films or etching, but stagnant gases accumulate in dead legs of the gas flow channels causing decomposition and substrate defects
Solution Approach 1:
The patent extracts the harmful stagnant gas accumulation problem by introducing a separate purge gas flow path that specifically targets and clears the dead legs of the gas flow channels. The purge gas flow path is designed to deliver purge gas directly to regions where stagnant gases accumulate, removing the harmful effect without disrupting the main process gas delivery function.
2Productivity
If gas flow channels are used to deliver process gases during substrate processing, then deposition and etching can be performed, but the gas flow channels create dead legs that require extended purge time, reducing processing efficiency
Solution Approach 1:
The patent segments the gas delivery system into distinct functional paths: a process gas flow path for delivering precursor and reactant gases, and a separate purge gas flow path for clearing stagnant gases. This segmentation allows the purge function to operate independently and efficiently, reducing the time required to clear dead legs without affecting the main processing function.
Solution Approach 2:
The purge gas acts as an intermediary substance that facilitates the removal of stagnant process gases from the dead legs. By introducing a dedicated purge gas flow, the system mediates the transition between different process gases more efficiently, reducing the time required to clear accumulated gases and enabling faster cycle times.
3Manufacturing precision
If traditional gas delivery systems are used with manifolds and valves, then gas can be delivered to the processing chamber, but the complex gas flow path creates dead legs that lead to non-uniform gas flow and affect substrate uniformity
Solution Approach 1:
The patent extracts the purge function from the complex manifold and valve system by providing a dedicated purge gas flow path. This separate path directly addresses the dead leg problem without requiring additional complexity in the main gas delivery system, maintaining substrate uniformity while simplifying the overall gas flow management.
4Area of stationary object
If gas is delivered through extended gas flow channels to reach all areas of the substrate, then complete coverage can be achieved, but the extended channels create larger dead leg volumes that accumulate more stagnant gas
Solution Approach 1:
The purge gas flow path serves as an intermediary system that specifically targets extended gas flow channels and their associated dead legs. By introducing purge gas through this dedicated path, the system effectively clears stagnant gases from extended channels without requiring the channels to be shorter, thus maintaining complete substrate coverage while reducing stagnant gas accumulation.
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 solution reduces ALD cycling time and improves substrate uniformity by minimizing dead leg volume and ensuring uniform gas flow, enhancing process efficiency and performance.
Implementation Method 1
a first passage provided in the body. The first passage connects the inlet to the plenum
Implementation Method 2
a second passage provided in the body. The second passage connects the outlet to the plenum
Implementation Method 3
a plurality of through holes provided on the lower surface of the body. The plurality of through holes are in fluid communication with the plenum and the processing chamber
Data Source
AI summary
A showerhead for a processing chamber comprises a body having upper, lower, and side surfaces defining a plenum; and a plurality of through holes provided on the lower surface of the body. The plurality of through holes are in fluid communication with the plenum and the processing chamber. The showerhead comprises an inlet provided on one of the upper and side surfaces of the body and a first passage provided in the body. The first passage connects the inlet to the plenum. The showerhead comprises an outlet provided on one of the upper and side surfaces of the body and a second passage provided in the body. The second passage connects the outlet to the plenum.