Extraction Plate Heat-Conduction Layout to Prevent Aperture Deposition
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Solution Overview
Problem
Condensation of feed gas on the extraction plate near the extraction aperture leads to deposition, which can block the ion beam and result in a nonuniform process during semiconductor device fabrication.
Innovation Solution
An extraction plate with thicker portions designed to capture and conduct heat from the hottest components in the ion source, such as the cathode, repeller, and side electrodes, to maintain an elevated temperature around the extraction aperture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the extraction plate is made with uniform thickness, then the manufacturing is simple, but the temperature distribution around the extraction aperture becomes non-uniform causing deposition
Solution Approach 1:
The extraction plate is designed with non-uniform thickness, featuring a thicker first portion positioned to receive heat from the cathode and a thinner second portion in other areas. This local variation in geometric property creates preferential thermally conductive paths that concentrate heat at the extraction aperture region, preventing feed gas condensation and deposition while maintaining manufacturing feasibility through standard machining processes.
2Productivity
If the extraction plate temperature near the extraction aperture is kept low, then feed gas ionization is efficient, but feed gas condenses and forms deposition blocking the ion beam
Solution Approach 1:
The extraction plate geometry is modified by varying the thickness parameter, creating a thicker first portion that acts as a heat capture region. This parameter change alters the thermal conduction characteristics, ensuring sufficient heat reaches the extraction aperture region to maintain temperatures above the feed gas condensation point, thereby preventing deposition while preserving ionization efficiency.
3Reliability
If the extraction plate has thicker portions to conduct heat, then the temperature around the extraction aperture is elevated preventing deposition, but the device complexity increases
Solution Approach 1:
Rather than uniformly increasing the entire extraction plate thickness, the design applies localized thickness variation with a thicker first portion only in the region required for heat capture from the cathode. This targeted approach achieves reliable deposition prevention through improved thermal conduction while minimizing additional material usage and structural complexity.
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
Prevents deposition by maintaining the region around the extraction aperture at an elevated temperature, ensuring a uniform ion beam and improving the consistency of the semiconductor fabrication process.
Implementation Method 1
heat from the cathode travels through the cathode heat capture region and the cathode heat conduction region to an area around the extraction aperture to increase a temperature of the area
Data Source
AI summary
An ion source and ion implantation system are disclosed that utilize an extraction plate that controls the flow of heat to create a region around the extraction aperture that has an elevated temperature. The extraction plate has thicker portions that correspond to the hottest components in the ion source. These thicker portions extend toward the extraction aperture to bring the heat toward the extraction aperture. The thicker portions may be located directly above the plasma generator, which may be an indirectly heated cathode. Further, the thicker portions may also be located directly above the repeller and/or side electrodes.