Semiconductor Thinning via Inverted Doping and Proton Implantation
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Solution Overview
Problem
Conventional methods for self-aligned thinning of semiconductor wafers face challenges in achieving precise and reproducible thickness with uniformity, particularly in avoiding over-doping and compensating effects that affect the space charge zone formation.
Innovation Solution
A method involving sequential proton implantations through opposite sides of the semiconductor body to create n-doped and p-doped zones, forming a pn-junction, which allows for controlled thinning by manipulating the space charge zone using bias voltage, enabling exact and reproducible thinning through electrochemical etching or mechanical removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If p-doped substrate is used as starting material for self-aligned thinning, then space charge zone can be formed, but the doping level must be precisely controlled to avoid counter-doping by thermal donors and strong compensation by proton irradiation
Solution Approach 1:
The patent inverts the conventional approach by using an n-doped substrate instead of a p-doped substrate as the starting material. This inversion allows the formation of a p-type space charge zone through proton irradiation without the problematic counter-doping effects that occur in p-type substrates. The n-doped substrate provides a clean baseline that can be precisely controlled during the thinning process.
Solution Approach 2:
The patent changes the fundamental doping parameter of the substrate from p-type to n-type. This parameter change fundamentally alters the interaction between the substrate and proton irradiation, eliminating the compensation effects and thermal donor formation issues that plague p-type substrates. The n-doped substrate enables precise thickness control while maintaining simple doping conditions.
2Manufacturing precision
If higher doses of surface proton irradiation are applied to avoid strong compensating of basic doping, then space charge zone extension is improved, but much higher irradiation doses are required
Solution Approach 1:
By inverting the substrate doping type from p-type to n-type, the patent eliminates the need for high proton irradiation doses. The n-doped substrate naturally supports space charge zone formation without the compensating effects that require excessive irradiation in p-type substrates, thereby reducing the energy input required.
Solution Approach 2:
The patent converts the previously harmful compensation effects in p-type substrates into a beneficial situation by using n-doped substrates. The proton irradiation now produces the desired space charge zone without unwanted compensation, turning a problematic interaction into a clean, efficient process that requires lower irradiation doses.
3Productivity
If conventional self-aligned thinning method is used, then thinning process can be performed, but reproducibility of wafer thickness and uniformity of wafer surface are difficult to achieve
Solution Approach 1:
The patent inverts the substrate doping type to n-type, which fundamentally improves the reproducibility and uniformity of the thinning process. The n-doped substrate provides consistent electrical properties that enable precise control of the space charge zone formation, leading to highly reproducible thickness results and uniform wafer surfaces across production batches.
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 ensures precise and reproducible thinning of semiconductor wafers, improving electrical properties by controlling the space charge zone, thus enhancing the reliability and yield of semiconductor components.
Implementation Method 1
forming an n-doped zone in the semiconductor body by a first implantation into the semiconductor body via the first side to a first depth location of the semiconductor body
Implementation Method 2
forming a p-doped zone in the semiconductor body by a second implantation into the semiconductor body via the second side to a second depth location of the semiconductor body
Implementation Method 3
enabling exact and reproducible thinning through electrochemical etching or mechanical removal
Data Source
AI summary
A method for producing a semiconductor is disclosed, the method having: providing a semiconductor body having a first side and a second side; forming an n-doped zone in the semiconductor body by a first implantation into the semiconductor body via the first side to a first depth location of the semiconductor body; and forming a p-doped zone in the semiconductor body by a second implantation into the semiconductor body via the second side to a second depth location of the semiconductor body, a pn-junction forming between said n-doped zone and said p-doped zone in the semiconductor body.