Ion Beam Scan Control for Accurate Wafer Dose Distribution
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Solution Overview
Problem
The existing ion implantation processes face challenges in accurately controlling the two-dimensional dose distribution on semiconductor wafers, particularly when beam sizes increase, leading to deviations in target beam current density distributions and increased adjustment times, which degrade productivity.
Innovation Solution
A method and apparatus that utilize a beam current matrix to define the relationship between beam current density and scan speed, allowing for precise calculation and correction of scan signals to achieve target beam current density distributions, even with varying beam sizes, by using a reciprocating scan with spot-like ion beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If beam size is increased to improve processing efficiency, then productivity is improved, but manufacturing precision deteriorates due to deviations in beam current density distribution
Solution Approach 1:
The patent applies parameter changes by measuring the actual beam current density distribution and using this measurement to calculate corrected scan speeds. The system changes the scan speed parameter dynamically based on the measured beam characteristics, allowing the beam size to be increased for higher productivity while maintaining precision through real-time parameter adjustment.
Solution Approach 2:
The patent implements feedback by measuring the beam current density distribution with a beam measurement device and using this measurement information to correct the scan speed. This closed-loop feedback system allows the beam size to be optimized for productivity while the measured deviations are compensated through scan speed adjustments, maintaining manufacturing precision.
2Manufacturing precision
If conventional beam current density control methods are used, then device complexity is reduced, but manufacturing precision deteriorates due to inability to accurately control dose distribution
Solution Approach 1:
The patent uses feedback by measuring the actual beam current density distribution and using this information to correct scan speeds. This measurement-feedback-correction loop enables precise dose distribution control while adding only minimal system complexity through the integration of a beam measurement device and correction calculation unit.
Solution Approach 2:
The patent replaces complex mechanical adjustment systems with a computational approach. Instead of mechanically adjusting beam parameters to control dose distribution, the system uses scan speed correction calculated from beam measurements, substituting mechanical complexity with computational processing.
3Manufacturing precision
If beam scan speed is adjusted to control dose distribution, then manufacturing precision is improved, but loss of time increases due to repeated measurements and adjustments
Solution Approach 1:
The patent applies preliminary action by performing beam measurements and calculating scan speed corrections in advance before actual ion implantation. This allows the system to prepare correction data beforehand, reducing adjustment time during production while maintaining manufacturing precision through pre-calculated scan speed modifications.
Solution Approach 2:
The patent uses parameter changes by establishing correction values for scan speeds based on measured beam characteristics. These correction parameters are calculated once and can be applied repeatedly, reducing the time needed for repeated measurements and adjustments while maintaining accurate dose distribution control.
4Manufacturing precision
If simple inverse proportionality between beam current density and scan speed is used, then device complexity is reduced, but manufacturing precision deteriorates when beam sizes vary
Solution Approach 1:
The patent applies parameter changes by replacing the simple inverse proportionality relationship with correction values derived from actual beam measurements. The system changes the control parameter from a fixed mathematical relationship to dynamically calculated correction factors that account for variations in beam size and characteristics, improving manufacturing precision.
Solution Approach 2:
The patent uses feedback to replace the simple inverse proportionality assumption with measurement-based correction. The beam measurement device provides feedback on actual beam current density, which is used to calculate accurate scan speed corrections, improving precision while the computational complexity is managed through automated calculation.
Data Source
AI summary
An ion implantation method includes generating a first scan beam, based on a first scan signal, measuring a beam current of the first scan beam by using a beam measurement device at a plurality of measurement positions, calculating a beam current matrix, based on a time waveform of the beam current measured by the beam measurement device and a time waveform of the scan command values determined in the first scan signal, calculating a first beam current density distribution of the first scan beam in a predetermined direction by performing time integration on the measured beam current, correcting a value of each component of the beam current matrix, based on the first beam current density distribution, and generating a second scan signal for realizing a target beam current density distribution in the predetermined direction, based on the corrected beam current matrix.