Ion Implantation Dose Correction via Neutral Particle Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current ion implantation systems fail to accurately control beam current during the implantation of photoresist-coated substrates due to unaccounted local variations in ambient pressure, leading to deviations in the delivered ion dose from the expected dose.
Innovation Solution
The method involves measuring the difference ratio of implant current to base current during calibration at base pressure and adjusting the scanning of the ion beam and substrate based on the current ratio to account for pressure-induced variations, using a closed loop Faraday current detector and a profiler current detector to ensure accurate dose delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current monitors are used to measure beam current during ion implantation, then beam current control is improved, but local variations in ambient pressure near the substrate are not accounted for, leading to dose inaccuracy
Solution Approach 1:
The patent introduces a neutral particle detector as an intermediary measurement device that indirectly senses local ambient pressure variations near the substrate by detecting pressure-induced changes in neutral particle flux. This mediator allows the system to account for local pressure effects without directly measuring pressure, thereby correcting beam current control to compensate for these variations and improve ion dose delivery accuracy.
2Reliability
If beam current is adjusted based on current monitor readings, then beam current control is improved, but unaccounted pressure variations cause the actual ion dose to deviate from expected dose
Solution Approach 1:
The patent implements a feedback mechanism where the neutral particle detector continuously monitors local pressure variations near the substrate during ion implantation. The system uses this feedback information to dynamically adjust beam current control, compensating for pressure-induced dose variations. This closed-loop feedback ensures that the actual ion dose delivered matches the expected dose despite local pressure fluctuations.
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 allows for precise control of beam current, reducing the deviation in actual implanted ion dose from the expected dose by accounting for pressure changes, thereby improving the accuracy and repeatability of ion implantation processes.
Implementation Method 1
a current sensor such as a Faraday cup may be provided adjacent to a substrate to intercept a spot beam scanned back and forth along a first direction
Implementation Method 2
scanning an ion beam along a first axis over a substrate, coated with a photoresist layer
Data Source
AI summary
A method, including using an implant recipe to perform an implant by scanning an ion beam along a first axis over a substrate, coated with a photoresist layer, while the substrate is scanned along a perpendicular axis; measuring an implant current (I) during the implant, using a first detector, positioned to a side of a substrate position; determining a value of a difference ratio (I−B)/(B), based upon the implant current, where B is current measured by the first detector, during a calibration at base pressure; determining a plurality of values of a current ratio (CR) for the plurality of instances, based upon the difference ratio, the current ratio being a ratio of the implant current to a current measured by a second detector, positioned over the substrate position, during the calibration; and adjusting scanning the ion beam, scanning of the substrate, or a combination thereof, based upon the current ratio.