Granular Sputter Source Target to Reduce Electrode Deposits
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Solution Overview
Problem
Conventional ion implantation systems face challenges in efficiently generating aluminum ions due to the use of insulating materials that cause high voltage instabilities and deposition on electrodes, leading to inefficiencies and reduced instrument lifespan.
Innovation Solution
The use of metal-coated ceramic granules as the source material in the ion source chamber, which provides a favorable thermal profile and increased reactive surface area, minimizing deposits and enhancing the etching process with a mixture of fluorine and inert gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional insulating materials (aluminum oxide, aluminum fluoride, aluminum nitride) are used as source material, then adequate vapor pressure and plasma stability are achieved, but deposits form on extraction electrodes within 5-10 hours causing high voltage instabilities
Solution Approach 1:
The source material is segmented into small granules (0.1-5 mm diameter) rather than using a monolithic block. This segmentation increases the total surface area available for etching, reduces the amount of material that can deposit on electrodes, and allows better gas flow distribution throughout the source chamber, thereby maintaining plasma stability while reducing harmful deposits.
Solution Approach 2:
The granule size and distribution are optimized to create local variations in etching rates and vapor generation. Smaller granules provide higher surface area density in certain regions, enhancing local etching efficiency and reducing the overall burden of deposits on extraction electrodes while maintaining stable plasma conditions.
2Device complexity
If monolithic solid material is used in the arc chamber, then the system structure is simple, but the reactive surface area is limited and etching efficiency is reduced
Solution Approach 1:
The monolithic solid material is divided into numerous small granules (0.1-5 mm diameter). This segmentation dramatically increases the total reactive surface area available for fluorine etching, thereby increasing the etch rate and aluminum ion generation efficiency while maintaining a relatively simple overall device structure.
Solution Approach 2:
The granulated source material creates a porous-like structure within the arc chamber, allowing etchant gas to penetrate and etch material from multiple directions simultaneously. This increases the effective reactive surface area and etching efficiency without requiring complex porous material structures.
3Quantity of substance
If external vaporizer is used to supply metal vapor, then adequate vapor pressure is achieved, but the system takes time to heat up and change species
Solution Approach 1:
The vapor generation function is merged directly into the arc chamber by placing granulated source material inside. This eliminates the need for a separate external vaporizer, allowing immediate vapor generation when the arc is struck and enabling rapid species changes by simply replacing granules rather than heating and cooling a separate oven.
Solution Approach 2:
The vapor generation function is extracted from a separate external vaporizer and integrated directly into the arc chamber environment. This takes out the time delay associated with external heating and allows the source material to be directly exposed to plasma and etchant gas for immediate vapor generation.
4Productivity
If granulated source material is used, then reactive surface area increases and etching efficiency improves, but source operating pressure increases
Solution Approach 1:
The granule size parameter is optimized (0.1-5 mm diameter) to balance surface area availability with pressure control. The size distribution is tuned to provide sufficient reactive surface area for high etch rates while maintaining appropriate inter-granule spacing to allow efficient gas flow and pressure management in the source chamber.
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 approach expedites ionization, reduces source operating pressure, and increases the etch rate, thereby improving ion beam formation efficiency and extending the instrument's lifespan.
Implementation Method 1
a cathode electrode disposed within the housing, the cathode electrode configured to inject electrons into the chamber once heated
Implementation Method 2
The plurality of metal-containing ceramic granules are positioned to contact a free flow of an etchant gas introduced into the housing to thereby generate a plurality of metal ions within the ion source chamber
Implementation Method 3
supplying a feed gas to the ion source chamber, the feed gas source configured to ionize the metal-containing ceramic granules to form an ion beam therefrom
Data Source
AI summary
The disclosure is generally directed to an ion implantation system and an ion source material associated therewith. More particularly, the present disclosure is directed to components for ion implantation system using an aluminum-based solid source material to produce ions for electrically doping silicon, silicon carbide, or other semiconductor substrates (i.e., wafer). The disclosed embodiments may be used at temperatures ranging up to 1000° C. The disclosed principles minimize deposits on extraction electrodes and source chamber components when using a pre-mixed etchant gas.