Ion Implantation Glitch Detection and Dynamic Threshold Repair
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Solution Overview
Problem
Ion implantation systems face challenges in achieving uniformity on larger semiconductor wafers due to ion beam discrepancies, such as arcing and intermittent ion implantation, which lead to time-consuming repairs and potential further issues during the re-tracing of the ion beam path.
Innovation Solution
A method is introduced to dynamically assess and address ion beam glitches by establishing a glitch duration threshold based on desired dose uniformity, number of passes, velocity, and beam size, where the ion implantation is halted only when the glitch duration exceeds this threshold, and the affected area is subsequently re-implanted by repositioning the workpiece and restarting the ion beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ion beam scanning is used to cover larger wafer areas, then productivity is improved, but manufacturing precision deteriorates due to non-uniform ion implantation
Solution Approach 1:
The system dynamically adjusts the glitch duration threshold based on real-time process conditions including scan velocity, beam size, and number of passes. This allows the system to adapt to varying scanning conditions across different wafer regions, maintaining dose uniformity while processing larger areas efficiently.
Solution Approach 2:
The invention changes the parameter of glitch tolerance by establishing a dynamic threshold that varies with process parameters such as scan velocity and beam dimensions. This enables the system to tolerate certain variations in larger area scanning while maintaining acceptable uniformity standards.
2Manufacturing precision
If conventional repair techniques are used to re-trace ion beam paths, then manufacturing precision is improved by filling non-implanted regions, but loss of time increases due to time-consuming repairs
Solution Approach 1:
The system changes the decision parameter from binary (repair or not) to a continuous dynamic threshold based on glitch duration, scan velocity, and beam size. This allows short glitches to be automatically tolerated without repair, eliminating unnecessary time loss while still repairing only when genuinely needed to maintain dose uniformity.
Solution Approach 2:
The system performs self-assessment of glitch impact by comparing actual glitch duration against the dynamically calculated threshold, automatically deciding whether repair is necessary without external intervention or conservative over-repair.
3Manufacturing precision
If glitch duration threshold is set low, then manufacturing precision is improved by repairing more glitches, but loss of time increases due to unnecessary repairs
Solution Approach 1:
The threshold is changed from a fixed low value to a dynamic parameter that scales with scan velocity, beam size, and number of passes. This allows the system to tolerate longer glitches during fast scans or when multiple passes are used, reducing unnecessary repairs and time loss while maintaining dose uniformity.
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 reduces unnecessary repairs, saves processing time, and maintains dose uniformity by selectively ignoring short glitches, thereby improving the efficiency and reliability of ion implantation processes.
Implementation Method 1
an ion source ionizes a desired dopant element, and the ionized impurity is extracted from the ion source as a beam of ions
Implementation Method 2
The ion beam is directed (e.g., swept or scanned) across respective workpieces to implant ionized dopants within the workpieces
Implementation Method 3
the high voltage typically necessary to supply the ion source is subject to occasional arcing between various extraction and suppression electrodes and other components associated therewith
Data Source
AI summary
A glitch duration threshold is determined based on an allowable dose uniformity, a number of passes of a workpiece through an ion beam, a translation velocity, and a beam size. A beam dropout checking routine repeatedly measures beam current during implantation. A beam dropout counter is reset each time beam current is sufficient. On a first observation of beam dropout, a counter is incremented and a position of the workpiece is recorded. On each succeeding measurement, the counter is incremented if beam dropout continues, or reset if beam is sufficient. Thus, the counter indicates a length of each dropout in a unit associated with the measurement interval. The implant routine stops only when the counter exceeds the glitch duration threshold and a repair routine is performed, comprising recalculating the glitch duration threshold based on one fewer translations of the workpiece through the beam, and performing the implant routine starting at the stored position.