Semiconductor Wafer Postdoping for Doping Uniformity
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Solution Overview
Problem
The production of semiconductor wafers with high dielectric strength is hindered by the inhomogeneous doping concentration along the length of single crystals produced by the magnetic Czochralski method, which affects the quality and consistency of semiconductor components, particularly for larger diameters like 12 inches, where conventional methods like the float-zone method are limited in diameter and doping uniformity.
Innovation Solution
A method involving postdoping of semiconductor wafers to achieve a defined basic doping concentration by using proton implantation and subsequent thermal processes to create hydrogen-induced donors, where parameters such as implantation dose and temperature are adjusted based on initial doping concentration measurements to ensure homogeneous doping across the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the magnetic Czochralski method is used to produce single crystals, then larger diameter wafers (e.g., 12 inches) can be produced, but the doping concentration becomes inhomogeneous along the length of the single crystal
Solution Approach 1:
The patent applies preliminary action by performing postdoping treatment after the single crystal is already grown by the magnetic Czochralski method. The basic doping is established during crystal growth, then additional dopants are introduced through ion implantation or diffusion processes to achieve the target doping concentration and uniformity in the drift region, without requiring complete redoping during the growth process itself.
Solution Approach 2:
The patent utilizes parameter changes by adjusting doping concentration through controlled thermal processes. By varying temperature parameters during annealing or diffusion steps, the dopant distribution is modified to achieve homogeneous doping in the drift region while maintaining the large wafer diameter capability of the magnetic Czochralski method.
2Manufacturing precision
If the float-zone method is used to produce single crystals, then homogeneous doping can be achieved, but the maximum diameter is limited to 8 inches
Solution Approach 1:
The patent merges the advantages of both methods by combining the magnetic Czochralski growth process (which enables large diameters) with postdoping treatments (which achieve homogeneous doping). This hybrid approach integrates the size capability of CZ with the doping precision previously only achievable by float-zone methods.
3Reliability
If a semiconductor substrate with exactly defined basic doping is produced, then high dielectric strength components can be manufactured, but production costs increase due to reduced multiplicity of components per wafer
Solution Approach 1:
The patent applies local quality by implementing selective postdoping that targets specific regions of the wafer. The drift region receives controlled doping to achieve the required dielectric strength, while other regions maintain their original doping characteristics. This localized approach ensures high reliability for power components while maintaining cost-effectiveness through optimized material usage.
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 the production of semiconductor wafers with consistent doping concentrations, enhancing the dielectric strength and efficiency of semiconductor components, particularly for larger diameters, by adapting the doping concentration to achieve uniformity and meet the requirements for high-voltage components.
Implementation Method 1
postdoping comprises at least one of the following methods: a proton implantation
Implementation Method 2
a subsequent thermal process for producing hydrogen induced donors
Implementation Method 3
a subsequent thermal process for producing hydrogen induced donors
Implementation Method 4
postdoping comprises at least one of the following methods: a neutron irradiation
Data Source
AI summary
A method for treating a semiconductor wafer having a basic doping is disclosed. The method includes determining a doping concentration of the basic doping, and adapting the basic doping of the semiconductor wafer by postdoping. The postdoping includes at least one of the following methods: a proton implantation and a subsequent thermal process for producing hydrogen induced donors. In this case, at least one of the following parameters is dependent on the determined doping concentration of the basic doping: an implantation dose of the proton implantation, and a temperature of the thermal process.