Czochralski Single Crystal Growth Resistivity Control
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Solution Overview
Problem
Current methods for growing silicon single crystals using the Czochralski process require complex doping procedures and significant process losses to achieve target resistivity values, leading to decreased productivity due to inaccuracies in impurity control within the raw materials.
Innovation Solution
A method that involves deriving resistivity values based on dopant concentrations in the raw material, setting reference values, calculating differences, and performing counter doping in the silicon melt to achieve target resistivity ranges of 8 to 14 kΩcm without controlling impurities, using a table correlating impurity concentrations with resistivity values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If impurity concentration in raw material is controlled to achieve target resistivity, then manufacturing precision of resistivity is improved, but device complexity and process complexity increase
Solution Approach 1:
The invention uses the inherent impurities in the raw material itself as the dopant source, eliminating the need for separate dopant addition equipment and processes. The raw material's own impurity concentration directly determines the resistivity, making the system self-regulating and reducing overall process complexity while maintaining resistivity control precision.
Solution Approach 2:
The invention changes the control parameter from active dopant addition to passive impurity concentration measurement. By measuring and utilizing the natural impurity concentration in the raw material rather than adding controlled amounts of dopants, the process simplifies while achieving the same resistivity control objective.
2Manufacturing precision
If sample processing and doping steps are performed to achieve target resistivity, then manufacturing precision is improved, but productivity deteriorates
Solution Approach 1:
The invention extracts and eliminates the unnecessary intermediate steps of sample processing and post-growth doping. By directly using the raw material's impurity concentration to achieve target resistivity, it removes these time-consuming processes entirely, thereby improving productivity without sacrificing resistivity control precision.
Solution Approach 2:
The invention performs the resistivity determination action in advance by measuring impurity concentration in the raw material before growth begins. This preliminary measurement allows direct calculation of expected resistivity and eliminates the need for post-growth sample processing and iterative doping adjustments, significantly reducing total process time.
3Ease of manufacture
If impurity concentration is not controlled in raw material, then ease of manufacture is improved, but manufacturing precision of resistivity deteriorates
Solution Approach 1:
The invention introduces a feedback mechanism where the measured impurity concentration of the raw material is used to calculate and predict the resulting resistivity. This feedback loop allows the system to compensate for variations in raw material quality by adjusting expectations and process parameters, maintaining manufacturing precision even when raw material impurity control is relaxed.
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 simplifies the process by allowing the growth of single crystal ingots with target resistivity values by measuring impurity concentrations directly, omitting sample processing and doping steps, thereby enhancing productivity and accuracy.
Implementation Method 1
polycrystalline silicon is melted by heat radiated from a heater to form a silicon melt
Implementation Method 2
a silicon single crystal is grown from a surface of the silicon melt
Data Source
AI summary
According to an embodiment of the present invention, there is provided a method for growing a single crystal ingot having a target resistivity in a silicon melt by the Czochralski method, including steps of: deriving a resistivity value according to a dopant concentration included in a raw material and tabulating the resistivity value with reliable data; setting a reference value of a dopant concentration with respect to a target resistivity value; deriving a measurement value with respect to the dopant concentration included in the raw material itself; calculating a difference value between the reference value and the measurement value; and performing a counter doping on the silicon melt as much as the difference value. Accordingly, a single crystal ingot having a resistivity of 8 kΩ or more can be grown without improving impurities included in the raw material itself.