Final Energy Magnet Calibration for Accurate Ion Implantation
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Solution Overview
Problem
The calibration of direct current (DC) final energy magnets (FEM) in ion implanters is time-consuming, requiring at least 12 hours and disrupting production, as it involves measuring energy shifts and adjusting magnetic fields to achieve accurate ion implantation depths and doses.
Innovation Solution
A method involving a wafer acceptance test (WAT) recipe, calculation of DC recipes, verification of tool energy shifts, and servo loop adjustments to tune the FEM, allowing for rapid calibration and accurate energy control with minimal experimental data points, reducing calibration time significantly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration method measuring energy shifts is used, then accurate ion implantation depth and dose are achieved, but calibration time increases to at least 12 hours
Solution Approach 1:
The patent changes the calibration parameter from measuring energy shifts (traditional method) to directly measuring ion implantation depth using secondary ion mass spectrometry (SIMS). This parameter change enables rapid calibration while maintaining accuracy, reducing calibration time from 12+ hours to significantly shorter duration.
Solution Approach 2:
The patent replaces the mechanical/time-consuming process of measuring energy shifts and adjusting magnetic fields with a direct measurement approach using SIMS technology. This substitution eliminates the need for lengthy iterative calibration procedures while achieving the same or better precision in ion implantation depth control.
2Manufacturing precision
If traditional calibration with extensive experimental data collection is performed, then accurate energy control is achieved, but production downtime increases
Solution Approach 1:
The patent performs preliminary calibration using SIMS measurement to establish the relationship between magnetic field strength and ion implantation depth before production. This preliminary action creates a calibration curve that can be used for rapid adjustments during production, minimizing downtime while maintaining precision.
Solution Approach 2:
The patent creates a calibration model or curve based on SIMS measurements that can be copied and applied to different production scenarios. This copying approach allows the system to maintain accurate energy control without repeating extensive experimental data collection for each production run.
3Manufacturing precision
If DC FEM magnetic field strength is adjusted for accurate ion path, then implantation depth precision is improved, but calibration complexity increases
Solution Approach 1:
The patent implements a self-service calibration approach where the SIMS measurement directly provides feedback on ion implantation depth, which is then used to adjust the magnetic field strength. This self-service mechanism simplifies the calibration procedure by eliminating the need for complex intermediate measurements and calculations.
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 enables efficient calibration of ion implanters, ensuring accurate ion implantation depths and doses, reducing production downtime and improving overall process efficiency by minimizing the need for extensive experimental data collection.
Implementation Method 1
A direct current (DC) final energy magnet (FEM) is used to control the energy of the implanting ion by controlling the strength of the magnetic field. The magnetic field with a tuned magnetic field strength causes the selected ions to travel in an accurate path with a particular momentum.
Data Source
AI summary
An ion implantation system comprising: a sample platform; an ion gun; an electrostatic linear accelerator; a direct current (DC) final energy magnet (FEM); and a processor. The processor is programmed to control: a wafer acceptance test instrument, a DC recipe calculator, a DC real energy calculator, and a tool energy shift verifier. The wafer acceptance test instrument is configured to apply a wafer acceptance test (WAT) recipe to a test sample on the sample platform. The DC recipe calculator is configured to calculate a recipe for the DC FEM. The DC real energy calculator is configured to calculate a real energy of the DC FEM. The tool energy shift verifier is configured to verify a tool energy shift of the DC FEM. The ion implantation system is configured to tune the DC FEM based on the verified tool energy shift, and obtain a peak magnetic field of the DC FEM.