Plasma Flood Gun Stabilizes Clamp Current for High Resistivity Wafers
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Solution Overview
Problem
Ion implantation systems face challenges in processing high bulk resistivity (HBR) semiconductor wafers due to unstable clamp currents, leading to handling errors and unnecessary shutdowns, as existing methods fail to maintain stable monitoring and wafer security.
Innovation Solution
Incorporating a plasma flood gun that generates a stabilizing flux of electrons to adjust the clamp current variation, using a controller to maintain the clamp current within a target value, and optimizing the power settings of the plasma flood gun to reduce fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrostatic clamps are used to hold HBR wafers during ion implantation, then wafer security and handling are improved, but clamp current stability deteriorates due to high bulk resistivity
Solution Approach 1:
A plasma flood gun is introduced as an intermediary device between the ion implantation system and the HBR wafer. The plasma flood gun generates a flux of electrons that act as a mediator to reduce surface resistance and stabilize clamp current, enabling reliable wafer handling without compromising current stability
Solution Approach 2:
The surface electrical parameters of the HBR wafer are dynamically changed by introducing plasma electrons. The plasma flood gun modifies the surface resistance characteristic from high resistivity to a more conductive state during processing, thereby stabilizing clamp current while maintaining wafer security
2Reliability
If safety mechanisms monitor clamp current for HBR wafers, then wafer handling errors are detected, but processing interruptions increase due to current fluctuations
Solution Approach 1:
The plasma flood gun is activated before and during ion implantation to preemptively stabilize the clamp current. By preparing the wafer surface with plasma electrons in advance, the system prevents current fluctuations that would otherwise trigger safety shutdowns, ensuring continuous processing
Solution Approach 2:
The high bulk resistivity of HBR wafers, which causes clamp current instability and processing interruptions, is converted into a benefit through plasma treatment. The plasma electrons exploit the high resistivity characteristic to create a controlled surface condition that stabilizes current flow, turning the harmful fluctuation source into a stable operating state
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 significantly improves clamp current stability, preventing interruptions during the implantation process and ensuring continuous operation by maintaining clamp current variations below a target value, even with high resistivity wafers.
Implementation Method 1
a plasma flood gun generating a flux of electrons impinging upon the substrate
Implementation Method 2
a plasma flood gun generating a flux of electrons
Implementation Method 3
an electrostatic clamp to hold a substrate
Data Source
AI summary
An ion implanter may include an electrostatic clamp to hold a substrate; a plasma flood gun generating a flux of electrons impinging upon the substrate; and a controller coupled to the plasma flood gun and including a component generating a control signal responsive to a measurement signal, the control signal to adjust operation of the plasma flood gun to a target operating level. At the target operating level the flux of electrons may comprise a stabilizing dose of electrons, the stabilizing concentration of electrons, the stabilizing concentration reducing a clamp current variation in the electrostatic clamp to a target value, the target value being less than a second value of clamp current variation when the plasma flood gun is not operating.