Conductive Member Crystallization by Isothermal Eutectic Diffusion
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Solution Overview
Problem
Existing methods for increasing crystal grain size in polycrystalline silicon channels face challenges in uniform temperature control, leading to non-uniform crystal growth and difficulty in obtaining flat crystals with uniform composition, especially when using slow cooling rates.
Innovation Solution
A method involving the formation of a first portion with a first element and a second element that causes an eutectic reaction, and a second portion with a third element forming an intermetallic compound, where the second element is diffused outward to grow crystal grains isothermally, eliminating the need for precise temperature control during cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If slow cooling rate is used to grow crystal grains, then crystal grain size is increased, but temperature control precision requirement increases and uniformity of crystal composition deteriorates
Solution Approach 1:
The invention changes the temperature parameter from a cooling process to an isothermal process. By maintaining a constant temperature within a specific range (400-600°C) during the diffusion process, the method achieves uniform crystal grain growth without the composition non-uniformity problems associated with slow cooling methods.
Solution Approach 2:
The invention introduces a metal element (second element) as an intermediary that facilitates crystal grain growth through diffusion. This metal element acts as a catalyst that enables grain growth at lower temperatures without requiring precise temperature control, thereby achieving uniform crystal composition while enlarging grain size.
2Length of stationary object
If slow cooling rate is used to grow crystal grains, then crystal grain size is increased, but process complexity and temperature control difficulty increase
Solution Approach 1:
The invention fundamentally changes the temperature parameter from a time-varying cooling process to a constant isothermal process. This eliminates the need for complex temperature control systems required for slow cooling, while still achieving large crystal grain size through diffusion-driven growth at constant temperature.
Solution Approach 2:
The invention replaces the mechanical cooling system with a chemical diffusion process. Instead of relying on controlled cooling rates to drive crystal growth, the method uses thermal diffusion of metal atoms at constant temperature, thereby simplifying the temperature control requirements.
3Reliability
If conventional crystallization method is used, then conductive member is formed, but crystal grain size remains small causing high channel resistance
Solution Approach 1:
The invention changes the temperature parameter to a lower range (400-600°C) and maintains it constantly, enabling crystal grain growth through diffusion while preserving the conductive properties of the material. This overcomes the limitation of conventional methods that produce small grains and high resistance.
Solution Approach 2:
The metal element serves as an intermediary that promotes crystal grain growth and improves electrical conductivity simultaneously. By controlling the diffusion of this metal element, the invention achieves both large grain size and low channel resistance, resolving the contradiction between reliable conductive member formation and large crystal grain size.
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
Enables the enlargement of crystal grains with improved controllability, resulting in a conductive member with uniform composition and larger grain size, suitable for use as semiconductor channels.
Implementation Method 1
growing crystal grains of the first element by diffusing the second element from the first portion into the second portion
Implementation Method 2
crystallizing primary crystals of the first element by adjusting a temperature of the substrate after bringing the first portion into a liquid phase state
Implementation Method 3
a second element, which causes an eutectic reaction with the first element
Data Source
AI summary
A method of forming conductive member includes: forming, on substrate, first portion containing first element constituting the conductive member to be obtained and second element causing eutectic reaction with the first element, and second portion containing third element constituting intermetallic compound with the second element; crystallizing primary crystals of the first element by adjusting temperature of the substrate after bringing the first portion into liquid phase state; growing crystal grains of the first element by diffusing the second element from the first portion into the second portion to increase ratio of the first element in crystal state to the first and second elements in the liquid phase state in the first portion while maintaining the temperature of the substrate at the same temperature; and turning the first portion, after completing diffusion of the second element into the second portion, into the conductive member having crystal grains of the first element.