Low-Temperature Dopant Activation in Semiconductor Fabrication
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Solution Overview
Problem
Conventional ion implantation methods for fabricating doped semiconductor zones require high annealing temperatures, which can damage thin wafers and prevent the early fabrication of metallic and plastic structures, making them unsuitable for thin-wafer technology and leading to difficulties in achieving highly doped zones near the surface or buried zones.
Innovation Solution
A method involving the implantation of dopant particles followed by irradiation with further particles, such as protons, helium ions, or argon ions, and subsequent thermal treatment at lower temperatures (less than 700°C) to activate the dopants, allowing for the fabrication of doped zones near the surface or buried zones without damaging thin wafers and enabling the early formation of metallic and plastic structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ion implantation methods are used to fabricate doped semiconductor zones, then dopant activation is achieved, but high annealing temperatures (800-1100°C) are required which can damage thin wafers and prevent early fabrication of metallic and plastic structures
Solution Approach 1:
The patent applies preliminary action by implanting dopant ions before thinning the wafer to the final thickness. This allows the doping process to be completed at an earlier stage when the wafer is still thick and robust, avoiding the need for high-temperature annealing after thinning. The dopant ions are implanted into the thicker wafer, then the wafer is thinned, and finally low-temperature annealing is performed to activate the dopants without damaging the thin structure or requiring re-thinning.
Solution Approach 2:
The patent changes the temperature parameter from conventional high temperatures (800-1100°C) to low temperatures (below 700°C, preferably 400-600°C) by combining ion implantation with a subsequent low-temperature annealing process. This parameter change enables dopant activation while preserving the integrity of thin wafers and allowing early fabrication of temperature-sensitive metallic and plastic structures.
2Reliability
If high annealing temperatures are used to activate dopant ions, then dopant activation is achieved, but metallic and plastic structures would melt, evaporate or decompose
Solution Approach 1:
The patent performs dopant ion implantation before fabricating the metallic and plastic structures. This preliminary action allows the doping process to be completed before the temperature-sensitive materials are introduced, so that subsequent low-temperature annealing will not expose these materials to damaging high temperatures.
Solution Approach 2:
The patent changes the annealing temperature parameter from the conventional high range (800-1100°C) to a low range (below 700°C, preferably 400-600°C). This parameter change ensures that metallic and plastic structures, which have lower melting and decomposition points, are not damaged during the dopant activation process.
3Productivity
If wafers are thinned to minimal thickness for vertical components, then component performance is improved, but the wafer becomes difficult to handle and susceptible to damage during fabrication
Solution Approach 1:
The patent performs dopant ion implantation and wafer thinning as preliminary actions before fabricating the final device structures. By completing these steps while the wafer is still relatively thick and robust, the wafer remains easy to handle during critical fabrication processes. The thinning is done before the wafer becomes too fragile, avoiding handling difficulties.
4Reliability
If dopant ions are implanted and then high-temperature annealing is performed, then dopant activation is achieved, but the process sequence requires metallic and plastic structures to be fabricated after doping
Solution Approach 1:
The patent performs dopant ion implantation as a preliminary action before fabricating metallic and plastic structures. The low-temperature annealing process enables these structures to be fabricated at any stage in the sequence, providing flexibility in the fabrication process. This eliminates the constraint that metals and plastics must be made after high-temperature doping, allowing more efficient process planning.
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 allows for the effective activation of dopant particles at lower temperatures, reducing the risk of wafer damage and enabling the early fabrication of metallic and plastic structures, suitable for thin-wafer technology, and achieving highly doped zones with improved latch-up behavior in power semiconductor components.
Implementation Method 1
In an implantation method, dopants are implanted into the semiconductor body by irradiating the semiconductor body with highly energetic dopant particles
Implementation Method 2
In order to activate these implanted dopant ions, that is to say to incorporate them at lattice sites of the crystal lattice of the semiconductor body, and in order to anneal crystal damage resulting from the irradiation, a thermal treatment of the semiconductor body is required after the particle implantation
Implementation Method 3
carrying out a thermal treatment by means of which the semiconductor body is heated, at least in the region containing the dopant particles, to a predetermined temperature in order to activate the implanted dopant particles, said temperature being less than 700° C.
Data Source
AI summary
One embodiment of the invention relates to a method for fabricating a doped semiconductor zone in a semiconductor body. The method includes implanting dopant particles via one side into the semiconductor body or applying a layer containing dopant particles to one side of the semiconductor body. The method also includes irradiating the semiconductor body via the one side with further particles at least in the region containing the dopant particles. The method finally includes carrying out a thermal treatment by means of which the semiconductor body is heated, at least in the region containing the dopant particles, to a predetermined temperature in order to activate the implanted dopant particles, said temperature being less than 700° C.