Ion Source Liner Mitigates Metal Ion Contamination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Direct current discharge ion sources in semiconductor manufacturing contaminate wafers with metal ions from high melting point materials used in the arc chamber, leading to reduced semiconductor device performance and frequent maintenance due to chemical bonding and corrosion by halogen radicals.
Innovation Solution
A DC discharge ion source with an arc chamber made of high melting point material and a liner formed of a more reactive material, such as silicon, to absorb and neutralize radicals, reducing the reaction with the arc chamber and extracting fewer heavy metal ions, thereby minimizing contamination and extending the ion source's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a high melting point material is used for the arc chamber, then the arc chamber can withstand high temperatures, but metal ions from the arc chamber react with halogen radicals and contaminate the semiconductor wafer
Solution Approach 1:
A liner made of silicon or silicon carbide is introduced as an intermediary layer between the halogen radicals and the high melting point arc chamber wall. The liner preferentially reacts with the halogen radicals, forming a protective barrier that prevents the radicals from attacking the arc chamber material, thereby eliminating metal ion contamination while maintaining high operating temperatures
Solution Approach 2:
The liner is designed as a sacrificial component that gradually consumes itself by reacting with halogen radicals over time. This disposable element protects the expensive arc chamber from contamination, extending the arc chamber's operational life while the liner can be periodically replaced at lower cost
2Strength
If a high melting point metal is used for the arc chamber, then the arc chamber maintains structural integrity at high temperatures, but the metal members are ionized and extracted as ion beam contaminants
Solution Approach 1:
The silicon or silicon carbide liner acts as a mediator that intercepts halogen radicals before they can reach the high melting point metal arc chamber wall. By forming silicon halide compounds, the liner prevents metal halide formation, ensuring that only the intended source gas ions are extracted in the ion beam without metal ion contamination
Solution Approach 2:
The liner creates a chemically inert environment between the reactive halogen radicals and the arc chamber metal wall. The silicon-based liner material forms a stable barrier that prevents unwanted chemical reactions, maintaining a clean interface that eliminates contamination sources while preserving the arc chamber's structural strength
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 solution effectively reduces the amount of heavy metal ions implanted into semiconductor wafers, decreases wear on ion source parts, and extends the ion source's operational life by mitigating radical reactions and corrosion, improving semiconductor device performance and productivity.
Implementation Method 1
a DC discharge ion source configured to emit thermoelectrons so that an arc chamber is heated inside to a high temperature
Implementation Method 2
generating ions by colliding source gas molecules and thermoelectrons with each other in the arc chamber and inducing plasma discharge
Implementation Method 3
causing radicals generated in generating ions to react with a liner provided to cover an inner wall of the arc chamber at least partially
Data Source
AI summary
An ion generation method uses a direct current discharge ion source provided with an arc chamber formed of a high melting point material, and includes: generating ions by causing molecules of a source gas to collide with thermoelectrons in the arc chamber and producing plasma discharge; and causing radicals generated in generating ions to react with a liner provided to cover an inner wall of the arc chamber at least partially. The liner is formed of a material more reactive to radicals generated as the source gas is dissociated than the material of the arc chamber.