Non-Uniform Ion Implantation for Wafer Doping Uniformity
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Solution Overview
Problem
Non-uniform doping across semiconductor wafers due to variations in dopant distribution during epitaxial growth leads to inconsistent electrical properties, affecting device performance and yield.
Innovation Solution
A method involving non-uniform ion implantation processes using an ion implantation system with a spot beam to correct non-uniform doping by adjusting the scanning speed of the substrate relative to the ion beam, combined with an implantation map to achieve targeted doping uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If epitaxial doping process is used to introduce dopant atoms during growth, then doping can be performed with precise control, but non-uniform doping concentration varies spatially across the wafer surface
Solution Approach 1:
The patent applies local quality by using a scanning ion beam that delivers different doping concentrations to different spatial locations on the substrate. The system varies the ion beam intensity and scanning speed across different regions to achieve the desired doping profile, allowing each location to receive precisely controlled dopant amounts according to its specific requirements.
Solution Approach 2:
The patent employs dynamics by implementing a moving ion beam that scans across the substrate surface. The beam position, scanning speed, and intensity are dynamically adjusted during the doping process to compensate for spatial variations and achieve uniform doping concentration across the entire wafer surface.
2Productivity
If temperature gradients and gas flow variations are present during epitaxial growth, then the growth process can proceed, but doping concentration becomes non-uniform across the substrate
Solution Approach 1:
The patent replaces the thermal and chemical field-based epitaxial doping process with a direct ion beam implantation method. This mechanical/electrical approach uses a focused ion beam to deliver dopant atoms directly to the substrate, eliminating the influence of temperature gradients and gas flow variations that plague conventional epitaxial doping.
3Ease of manufacture
If conventional uniform ion implantation is performed, then the entire substrate receives the same doping dose, but it cannot correct existing non-uniform doping patterns
Solution Approach 1:
The system uses dynamic control of the ion beam scanning parameters, varying the beam intensity and scanning speed across different substrate regions to deliver non-uniform doping doses that specifically address and correct the measured non-uniformities in the existing doping profile.
Solution Approach 2:
The patent implements a feedback mechanism where the doping process is guided by measurements of the existing doping profile. The system uses this information to calculate and apply compensatory doping patterns, creating a closed-loop process that continuously corrects non-uniformities based on actual substrate conditions.
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
Improves doping uniformity and corrects defects in semiconductor substrates, enhancing device reliability and reducing the need for multiple substrates in dose testing.
Implementation Method 1
performing a non-uniform ion implantation process on the semiconductor substrate to create a second difference between the first average doping concentration level and the second average doping concentration level
Data Source
AI summary
A method for improving doping uniformity in a semiconductor substrate, including placing the semiconductor substrate in an epitaxial growth chamber, performing an epitaxial doping process on the semiconductor substrate, whereafter a first portion of the semiconductor substrate exhibits a first average doping concentration level and a second portion of the semiconductor substrate exhibits a second average doping concentration level, where there is first difference between the first average doping concentration level and the second average doping concentration level, transferring the substrate to a process chamber of an ion implantation system, and performing a non-uniform ion implantation process on the semiconductor substrate to create a second difference between the first average doping concentration level and the second average doping concentration level, where the second difference is less than the first difference.