Cold Block and Gas Jet for Monocrystalline Silicon Sheet Growth
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Solution Overview
Problem
Existing methods for growing crystalline silicon sheets, such as vertical pulling and horizontal ribbon growth, face challenges in achieving uniform thickness and high-quality monocrystalline production due to inadequate heat removal rates, leading to multi-grain silicon and poor crystallization.
Innovation Solution
A system comprising a cold block and a nozzle that delivers a gas jet to the melt surface, creating a process zone with a high heat removal rate, exceeding 100 W/cm2, to facilitate the growth of a continuous, wide, and uniform monocrystalline silicon ribbon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If radiative cooling is used to form crystalline silicon, then the method provides an alternative to vertical pulling and horizontal ribbon growth, but the heat removal rate is insufficient to properly crystallize the silicon sheet
Solution Approach 1:
The patent introduces an intermediary cooling system consisting of a cold block and gas jet that acts as a mediator between the silicon melt and the cooling mechanism. This intermediary system enables efficient heat transfer from the melt surface to the cold block, achieving the necessary heat removal rate for proper crystallization while maintaining the benefits of a alternative growth method
Solution Approach 2:
The patent replaces the insufficient radiative cooling mechanism with a enhanced cooling system that uses a cold block and gas jet. This substitution provides a more effective heat removal mechanism that can achieve the required heat flux densities for reliable monocrystalline growth, overcoming the limitations of pure radiative cooling
2Quantity of substance
If vertical pulling or horizontal ribbon growth is used, then crystalline sheets can be produced, but temperature gradients result in poor quality multi-grain silicon
Solution Approach 1:
The patent applies local quality by creating a localized process zone directly above the cold block where intense cooling occurs. This localized heat removal creates a controlled temperature gradient that promotes monocrystalline growth in the region of interest while minimizing the formation of multi-grain structures in other areas
Solution Approach 2:
The patent changes the thermal parameters by introducing a cold block with controlled temperature and a gas jet flow rate. By adjusting these parameters, the system achieves optimal heat removal rates that promote high-quality monocrystalline growth, transforming the temperature distribution to favor single-grain formation over multi-grain structures
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
The system effectively removes heat at a rate sufficient for producing high-quality monocrystalline silicon sheets with a (111) crystallographic facet, achieving peak heat removal rates of up to 1000 W/cm2, ensuring rapid and uniform crystallization with low defect levels.
Implementation Method 1
a cold block and configured to generate a cold block temperature at the cold block surface that is lower than a melt temperature of the melt at the exposed surface
Implementation Method 2
a nozzle disposed within the cold block and configured to deliver a gas jet to the exposed surface, wherein the gas jet and the cold block are interoperative to generate a process zone that removes heat from the exposed surface
Implementation Method 3
System and method for crystalline sheet growth using a cold block and gas jet
Data Source
AI summary
A crystallizer for growing a crystalline sheet from a melt may include a cold block having a cold block surface that faces an exposed surface of the melt, the cold block configured to generate a cold block temperature at the cold block surface that is lower than a melt temperature of the melt at the exposed surface. The system may also include a nozzle disposed within the cold block and configured to deliver a gas jet to the exposed surface, wherein the gas jet and the cold block are interoperative to generate a process zone that removes heat from the exposed surface at a first heat removal rate that is greater than a second heat removal rate from the exposed surface in outer regions outside of the process zone.