Induction Heating Crystallization of Semiconductor Thin Films
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Solution Overview
Problem
Conventional methods for crystallizing low-concentration semiconductor thin films, such as thermal treatment and metal-induced crystallization, are either time-consuming or introduce metal impurities, limiting substrate materials and device performance.
Innovation Solution
A method involving induction heating using photo-charges generated by an external light source to crystallize low-concentration semiconductor layers without a separate pre-heating process, allowing for efficient crystallization on a wide range of substrates while minimizing impurity introduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal treatment is used to crystallize low-concentration semiconductor thin film, then crystallization is achieved, but the process time becomes excessively long (4 or more hours at 700°C)
Solution Approach 1:
The patent replaces the conventional thermal field (heat treatment) with an electromagnetic field (induction heating) to crystallize the semiconductor thin film. By using alternating magnetic field generated by induction coil, the amorphous silicon layer is directly heated to crystallization temperature without requiring prolonged thermal treatment, thus reducing process time from hours to minutes while maintaining crystallization quality
Solution Approach 2:
The patent changes the heating mechanism from conventional thermal conduction to electromagnetic induction heating. By controlling the frequency and intensity of the alternating magnetic field, the crystallization process is accelerated significantly. The induction heating allows rapid temperature rise to the crystallization point followed by quick cooling, achieving high-quality crystallization in much shorter time compared to traditional slow thermal treatment
2Temperature
If MIC (metal induced crystallization) method is used, then low-temperature crystallization is achieved, but metal impurities are introduced into the silicon thin film causing device characteristic deterioration
Solution Approach 1:
The patent replaces the chemical mechanism (metal-induced crystallization) with a physical mechanism (electromagnetic induction heating). Instead of using metal catalysts like Al or Ni to induce crystallization at low temperatures, the patent uses induction coil to generate alternating magnetic field that directly heats the silicon layer, achieving crystallization without introducing any metal impurities into the film
Solution Approach 2:
The patent introduces an induction coil as an intermediary device that transfers energy from the power source to the silicon layer through electromagnetic induction. The coil acts as a non-contact heating element, allowing temperature control and crystallization without direct contact between metal catalysts and the silicon film, thereby avoiding contamination while maintaining low-temperature processing advantages
3Productivity
If conventional induction heating is used on low-concentration semiconductor, then high-concentration crystallization is achieved, but the method is not suitable for low-concentration films requiring separate impurity reduction process
Solution Approach 1:
The patent optimizes the induction heating parameters (frequency, power, duration) specifically for low-concentration semiconductor films. By controlling the electromagnetic field intensity and exposure time, the crystallization process achieves high efficiency while maintaining the low impurity concentration characteristic of the original film, eliminating the need for subsequent impurity reduction processes
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 enables the rapid and cost-effective production of high-quality, low-concentration crystalline semiconductor thin films with improved carrier mobility and long life cycles, suitable for switching devices, using inexpensive substrates like glass without overheating the substrate.
Implementation Method 1
an alternating current generated by a current generator (151) is applied to flow through the induction coil (152), so that an alternating magnetic field affects the amorphous silicon layer (130)
Implementation Method 2
Carriers in a portion (b) of the amorphous silicon layer (130) under the induction coil are rotated by the alternating magnetic field, so that Ohmic Heating occurs
Implementation Method 3
Carriers in a portion (b) of the amorphous silicon layer (130) under the induction coil (152) are rotated by the alternating magnetic field, so that Ohmic Heating occurs
Implementation Method 4
the fluid-state portion is crystallized in an interface (d) between the portion (b) and solid-state portions (a) and (c) by using the solid-state portions (a) and (c) as a seed
Data Source
AI summary
Provided is a method of manufacturing a crystalline semiconductor thin film formed on an amorphous or poly-crystalline substrate such as a glass substrate, a ceramic substrate, and a plastic substrate through induction heating using photo-charges. The method of manufacturing a crystalline semiconductor thin film includes a process of forming a low-concentration semiconductor layer on an inexpensive amorphous or poly-crystalline substrate such as a glass substrate, a ceramic substrate, and a plastic substrate and a process of crystallizing the low-concentration semiconductor layer through an induction heating manner using photo-charges. Accordingly, a low-concentration crystalline semiconductor thin film having characteristics better than those of general amorphous or poly-crystalline semiconductor thin film can be obtained by using simple processes at low production cost.