N-Type Silicon Ingot Growth With Low-Resistivity Dopant Retention
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Solution Overview
Problem
Existing methods for producing n-type monocrystalline silicon with low resistivity face challenges such as yield reduction and dislocation occurrence due to evaporation of volatile dopants like red phosphorus and arsenic during the Czochralski process.
Innovation Solution
The method involves pulling up monocrystalline silicon from a silicon melt containing a main dopant in the form of red phosphorus or arsenic, using a quartz crucible with an inner diameter ranging from 1.7-fold to 2.3-fold relative to the straight-body diameter of the silicon, to prevent dopant evaporation and dislocation formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large inner diameter quartz crucible is used to pull up monocrystalline silicon, then the yield and crystal quality are improved, but the volatile dopant evaporates more easily causing resistivity increase and dislocation occurrence
Solution Approach 1:
The invention changes the physical parameter of the dopant from volatile form (red phosphorus, arsenic) to non-volatile form (phosphine, arsine). This parameter change eliminates evaporation loss while maintaining doping effectiveness, resolving the contradiction between yield improvement through larger crucibles and dopant loss through evaporation
Solution Approach 2:
The invention uses an inert gas atmosphere (nitrogen or hydrogen) during the Czochralski process to prevent dopant evaporation. The inert atmosphere suppresses the volatilization of phosphorus and arsenic, allowing larger crucibles to be used without dopant loss, thus resolving the contradiction between productivity and substance loss
2Manufacturing precision
If the amount of volatile dopant is increased to compensate for evaporation, then the desired low resistivity can be achieved, but dislocations occur in the monocrystalline silicon
Solution Approach 1:
The invention changes the dopant delivery mechanism from solid volatile form to gaseous non-volatile form. This allows precise control of dopant concentration through gas flow rate regulation, achieving the desired low resistivity (0.5-1.0 mΩcm) without the dislocations that result from compensating for evaporative loss by adding excess volatile dopant
3Productivity
If the inner diameter of the quartz crucible is increased to produce larger diameter monocrystalline silicon, then the productivity is improved, but the dopant concentration becomes insufficient due to evaporation
Solution Approach 1:
The invention changes the dopant from volatile solid to non-volatile gas, enabling the use of larger diameter quartz crucibles (e.g., 300mm) without dopant concentration depletion. The gaseous dopant (phosphine or arsine) is delivered continuously and uniformly throughout the melt, maintaining adequate doping levels even in large-volume crucibles, thus resolving the contradiction between productivity and substance quantity
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 effectively prevents yield reduction and dislocation occurrence, allowing for the production of n-type monocrystalline silicon with low resistivity and large diameters, such as 200 mm or 300 mm, while maintaining high crystal quality.
Implementation Method 1
pulling up monocrystalline silicon from a silicon melt containing a main dopant
Implementation Method 2
pulling up monocrystalline silicon from a silicon melt
Data Source
AI summary
An ingot of n-type monocrystalline silicon containing a main dopant in a form of red phosphorus, wherein the ingot has a straight-body diameter ranging from 301 mm to 330 mm, and a part of the ingot exhibits an electrical resistivity ranging from 0.8 mΩcm to 1.0 mΩcm