Ion Beam Profile Measurement via Current Normalization
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Solution Overview
Problem
Ion implantation systems face challenges in achieving uniform doping of semiconductor wafers due to non-uniformity in ion beam current, particularly because existing methods struggle to reliably measure time-independent ion beam profiles amidst fluctuations in beam current over time.
Innovation Solution
A system and method that utilize a beam profiling apparatus to measure ion beam current across the width of the ion beam while a beam monitoring apparatus measures the ion beam current at an edge, with both measurements synchronized and sampled concurrently to normalize the data, thereby canceling out fluctuations and achieving a time-independent ion beam profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a beam profiling apparatus measures ion beam current across the width of the ion beam, then the spatial distribution of beam intensity is obtained, but time-dependent fluctuations in beam current contaminate the measurement, making it impossible to reliably determine the time-independent beam profile
Solution Approach 1:
A beam monitoring apparatus is introduced as an intermediary device to measure the total beam current independently. This monitoring apparatus serves as a mediator that captures the time-dependent fluctuations separately, allowing the profiling apparatus data to be corrected by dividing out the fluctuation component. The monitoring apparatus acts as a reference that enables separation of spatial distribution from temporal variations.
Solution Approach 2:
The system implements feedback by continuously monitoring the total beam current and using this information to normalize the beam profile measurements. The measured fluctuations are fed back into the data processing chain, where they are used to correct the spatial distribution data in real-time, ensuring that the final beam profile represents only the spatial characteristics without temporal contamination.
2Manufacturing precision
If the ion beam current fluctuates during the measurement process, then the measured beam profile contains both spatial distribution and temporal variation, but only the time-independent spatial profile is needed for uniform doping
Solution Approach 1:
The invention extracts the time-dependent fluctuation component from the total measurement signal. By using the beam monitoring apparatus to independently measure total current variations, the temporal variation information is separated and removed from the beam profile data through normalization. This leaves only the spatial distribution information needed for achieving uniform doping.
Solution Approach 2:
The measurement system is segmented into two independent functional components: a beam profiling apparatus that captures spatial distribution and a beam monitoring apparatus that captures temporal fluctuations. This segmentation allows independent measurement and processing of spatial and temporal characteristics, enabling clean separation of the two types of information through subsequent normalization.
3Area of stationary object
If a small-sized ion beam is scanned rapidly to cover a large workpiece area, then the doping uniformity can be achieved, but non-linearity in the beam scan and optics creates non-uniformity in the beam scan direction
Solution Approach 1:
The beam profile is measured and characterized before the actual doping process. By obtaining the time-independent spatial distribution data through the normalization method, any non-uniformities in the beam scan direction are identified in advance. This preliminary characterization allows for pre-correction strategies to be implemented, ensuring uniform doping across the entire workpiece area.
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 determination of a time-independent ion beam profile, enhancing the uniformity of doping on semiconductor wafers by accounting for and compensating for ion beam current fluctuations during the measurement process, thereby improving the accuracy and reliability of ion implantation systems.
Implementation Method 1
measure the ion beam current across a width of the ion beam concurrent with the translation
Implementation Method 2
measure the ion beam current at an edge of the ion beam concurrent with the duration of beam profiling measurement
Implementation Method 3
an ion source for generating electrically charged ions from ionizable source materials
Implementation Method 4
The generated ions are formed into a high speed beam with the help of a strong electric field and are directed along a predetermined beam path
Data Source
AI summary
An ion implantation system and method are provided where an ion source generates an ion and a mass analyzer mass analyzes the ion beam. A beam profiling apparatus translates through the ion beam along a profiling plane in a predetermined time, wherein the beam profiling apparatus measures the beam current across a width of the ion beam concurrent with the translation, therein defining a time and position dependent beam current profile of the ion beam. A beam monitoring apparatus is configured to measure the ion beam current at an edge of the ion beam over the predetermined time, therein defining a time dependent ion beam current, and a controller determines a time independent ion beam profile by dividing the time and position dependent beam current profile of the ion beam by the time dependent ion beam current, therein by cancelling fluctuations in ion beam current over the predetermined time.