Ion Beam Angle Measurement Using Resistive Pillars
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Solution Overview
Problem
Current ion beam angular measurement techniques in ion implantation are inaccurate and cumbersome, especially at low energies below 50 keV, requiring complex structures and multiple masks, which are costly and time-consuming, and fail to provide real-time precision necessary for advanced semiconductor fabrication.
Innovation Solution
The use of high aspect ratio pillars on an insulating layer within an ion implantation system allows for resistivity measurements before, during, and after ion implantation, enabling precise adjustment of the ion beam angle for improved uniformity and tighter process control using a single or two-mask process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional angular measurement techniques are used, then measurement can be performed, but measurement precision deteriorates at low energies below 50 keV
Solution Approach 1:
The patent replaces mechanical measurement tools with electrical resistivity measurement. Instead of using mechanical apparatus to physically measure beam angle, the invention uses changes in electrical resistivity of silicon pillars caused by ion implantation to indirectly determine the beam angle. This substitution enables precise measurement at low energies where mechanical methods fail.
Solution Approach 2:
The patent introduces silicon pillars as an intermediary medium between the ion beam and the measurement system. The pillars absorb ion implantation damage in a角度-dependent manner, converting the physical beam angle into an electrical resistivity signal that can be measured precisely. This intermediary enables indirect measurement with high precision at low energies.
2Measurement precision
If transistor structures with multiple masks are used for angular measurement, then measurement capability is achieved, but device complexity increases
Solution Approach 1:
The patent extracts the measurement function from complex transistor structures and implements it using simple silicon pillars formed by a single photolithography step. By separating the measurement purpose from the device structure, the invention achieves angular measurement capability with minimal processing complexity - just one mask step to define the pillar positions.
Solution Approach 2:
The patent changes the measurement approach from electrical characteristics of complex transistor structures to physical resistivity changes of simple silicon pillars. This parameter change simplifies the device structure while maintaining measurement capability, requiring only basic pillar formation and resistivity measurement without complex transistor fabrication.
3Measurement precision
If periodic angular measurement is performed using mechanical tools, then measurement is possible, but productivity decreases due to lack of real-time feedback
Solution Approach 1:
The patent implements feedback by measuring resistivity changes of silicon pillars during or after ion implantation to determine beam angle. This electrical measurement provides immediate feedback on beam positioning, enabling real-time or near-real-time adjustment of implantation parameters without waiting for periodic mechanical measurements or device fabrication cycles.
Solution Approach 2:
The patent replaces periodic mechanical measurement tools with continuous electrical resistivity measurement. Electrical measurements can be performed rapidly and repeatedly, providing real-time data on beam angle while the implantation process is ongoing or immediately afterward, dramatically improving measurement frequency and productivity.
4Measurement precision
If ion channeling effect is used for angular measurement, then measurement can be performed at high energies, but manufacturing precision deteriorates at low energies below 5 keV
Solution Approach 1:
The patent changes the measurement mechanism from ion channeling (which requires high energy) to resistivity measurement of implantation damage (which works at any energy). By measuring the electrical resistance changes caused by ion implantation in silicon pillars rather than relying on channeling effects, the invention achieves precise angular measurement and control at low energies below 5 keV where channeling is ineffective.
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 method enables accurate and efficient measurement of ion beam angles at low energies, reducing the need for complex structures and multiple masks, thereby improving angular uniformity and process control in semiconductor fabrication.
Implementation Method 1
dopant atoms/molecules are ionized and isolated, sometimes accelerated or decelerated, formed into a beam, and swept across a workpiece or wafer. The dopant ions physically bombard the workpiece, enter the surface and come to rest below the surface
Implementation Method 2
resistivity measurements are taken for each of the composite pillars before and after test ion beam implantation, and wherein the resistivity measurements yield information relating to an angle of the ion beam during test
Data Source
AI summary
The present invention involves an ion beam angular measurement apparatus for providing feedback for a predetermined set ion beam angle comprising an arrangement of composite pillars formed on an insulating material and wherein the composite pillars selectively allow ion beams to penetrate a first layer of a pillar, wherein resistivity measurements are taken for each of the composite pillars before and after test ion beam implantation and wherein the resistivity measurements yield information relating to an angle of the ion beam during test.