Pulsed Ion Beam Source for Non-Conductive Target Sputtering
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Solution Overview
Problem
Ion beam deposition systems face challenges when dealing with non-conductive materials due to target charging, leading to arcing issues, and existing solutions like hot wires and plasma sources have limitations such as contamination, reliability concerns, and high costs.
Innovation Solution
A pulsed ion beam source with a grid and power supply system that temporarily interrupts the ion beam to allow for electron neutralization, using a DC supply, FETs, diodes, and a pulse generator to manage the grid voltage and detect arcs, preventing arcing without the need for secondary electron sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a continuous ion beam is used to sputter a non-conductive target, then the deposition rate is high, but the target becomes charged and arcing occurs
Solution Approach 1:
The ion beam is pulsed on and off periodically. During the off-period, electrons neutralize the positive charge accumulated on the insulating target surface. During the on-period, ion bombardment occurs for deposition. This periodic action prevents continuous charging while maintaining net deposition, resolving the contradiction between high deposition rate and arcing prevention.
2Reliability
If a secondary electron source (hot wire or plasma source) is added to neutralize target charge, then arcing is prevented, but device complexity and cost increase
Solution Approach 1:
The patent removes the secondary electron source component entirely from the system. Instead of adding complexity with hot wires or plasma sources, it extracts this function and achieves charge neutralization through the timing of the pulsed ion beam itself, using only the ion source and power supply that are already required for deposition.
Solution Approach 2:
The ion beam system serves its own charge neutralization needs through its own pulsed operation. The periodic interruption of the ion beam allows the natural electron population in the plasma to neutralize target charge, making the system self-sufficient without requiring separate electron sources.
3Reliability
If a hot wire electron source is used, then target charging is neutralized, but contamination and reliability issues arise
Solution Approach 1:
The hot wire component is completely removed from the system. The patent extracts the charge neutralization function from the hot wire and implements it through the pulsed ion beam timing, thereby eliminating the source of contamination while maintaining charge neutralization capability.
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
Enables efficient sputtering of non-conductive materials by preventing target charging and arcing, maintaining deposition quality and reducing contamination and cost concerns, as demonstrated by consistent SiO2 film thickness and refractive index across a wafer.
Implementation Method 1
a grid for extracting ions and a power supply for supplying pulsed power to the grid to extract the ions
Implementation Method 2
This provides sufficient time for electrons generated in the ion source and/or chamber plasma to neutralise sufficiently, and have substantially discharge, the target
Implementation Method 3
an apparatus for sputtering a non-conductive target
Data Source
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AI summary
This invention relates an ion beam source (10) for use with a non-electrical conducting target (14) including a grid (13) for extracting ions and a power supply for supplying pulsed power to the grid (13) to extract the ions.