·Epitaxial technology allows for the growth of higher purity film layers on substrates of the same material.
·During the epitaxial process, the direction of growth is determined by the underlying substrate crystal.
·The epitaxial process affects device quality, characteristics, electrical performance, etc.
Epitaxial growth of gallium arsenide on silicon substrate
Building integrated circuits or semiconductor devices on a perfect crystal foundation layer is an ideal choice. The epitaxial (epi) process in semiconductor manufacturing aims to deposit a fine single crystal layer on a single crystal substrate, typically ranging from 0.5 to 20 micrometers. Epitaxial process is an important step in semiconductor device manufacturing, especially in silicon wafer manufacturing.
Overview of Epitaxial Processes in Semiconductor Manufacturing | |
What is it | The epitaxial (epi) process in semiconductor manufacturing allows for the growth of thin crystal layers in a given orientation on top of a crystal substrate. |
goal | In semiconductor manufacturing, the goal of epitaxial processes is to enable more efficient transmission of electrons through the device. In the construction of semiconductor devices, epitaxial layers are included to refine and make the structure uniform. |
Process | Epitaxial technology allows for the growth of higher purity layers on substrates of the same material. In some semiconductor materials, such as heterojunction bipolar transistors (HBTs) or metal oxide semiconductor field-effect transistors (MOSFETs), epitaxial processes are used to grow material layers different from the substrate. It is the epitaxial process that makes it possible to grow low-density doped layers on highly doped material layers. |
In the epitaxial process, the direction of growth is determined by the underlying substrate crystal. Depending on the repetition of deposition, there may be one or more epitaxial layers. Epitaxial technology can be used to form thin layers of materials with the same or different chemical composition and structure as the underlying substrate.
Two types of Epi processes | ||
feature | Growth layer | Heteroepitaxy |
Grow | The material of the epitaxial growth layer is the same as that of the substrate layer | The material of the epitaxial growth layer is different from that of the substrate layer |
Crystal structure and lattice | The crystal structure and lattice constant of the substrate and epitaxial layer are the same | The crystal structure and lattice constant of the substrate and epitaxial are different |
Example | Epitaxial growth of high-purity silicon on silicon substrate | Epitaxial growth of gallium arsenide on silicon substrate |
Application | Semiconductor device structures require layers with different doping levels or pure films on less pure substrates | The structure of semiconductor devices requires layers of different materials or the construction of crystal films of materials that cannot be obtained as single crystals |
Factor | Description |
Temperature | Affects the epitaxial rate and epitaxial layer density. The temperature required for epitaxial process is higher than room temperature, and this value depends on the type of epitaxial process. |
Pressure | Affects the epitaxial rate and epitaxial layer density. |
Defect | Defects in epitaxy result in defective chips. The physical conditions required for epitaxial process should be maintained for defect free epitaxial layer growth. |
Expected position | The epitaxial process should grow on the correct position of the crystal. Areas that do not require growth during this process should be appropriately coated to prevent growth. |
Self doping | Due to the epitaxial process being carried out at high temperatures, dopant atoms may be able to bring about changes in the material. |
The density of epitaxial growth is the number of atoms per unit volume of material in the epitaxial growth layer. Factors such as temperature, pressure, and the type of semiconductor substrate affect epitaxial growth. Usually, the density of the epitaxial layer varies with the above factors. The growth rate of the epitaxial layer is called the epitaxial rate.
If epitaxial growth is carried out in the appropriate position and orientation, the growth rate will be very high, and vice versa. Similar to the density of epitaxial layers, the epitaxial rate also depends on physical factors such as temperature, pressure, and substrate material type.
The epitaxial rate increases at high temperature and low pressure. The epitaxial growth rate also depends on the orientation of the substrate structure, the concentration of reactants, and the growth technique used.
There are several methods of epitaxial technology, including liquid-phase epitaxy, mixed vapor phase epitaxy, solid-phase epitaxy, atomic layer deposition, chemical vapor deposition, molecular beam epitaxy, etc. Let's compare two epitaxial processes: CVD and MBE.
The most commonly used methodChemical Vapor Deposition (CVD) | Molecular Beam Epitaxy (MBE) |
chemical | physical |
Chemical reactions that occur when gas precursors meet heated substrates in growth chambers or reactors | Heating the material to be deposited under vacuum conditions |
Accurate control of thin film growth process | Accurately control the thickness and composition of the growth layer |
For applications that require high-quality epitaxial layers | For applications that require extremely thin epitaxial layers |
More expensive methods |
Epitaxial process is crucial in semiconductor manufacturing; It optimizes the performance of semiconductor devices and integrated circuits. It is one of the main processes in semiconductor device manufacturing that affects device quality, characteristics, and electrical performance.
The low-temperature selective epitaxial platform independently developed by Yuanlei Nano has achieved a series of breakthrough innovations in manufacturing, energy consumption, and production efficiency, and has become the third epitaxial device for heating lamp tube design in the world. This device can be used for silicon-based homogeneous and heterogeneous epitaxial growth such as 8/12 inch logic, storage, and epitaxial wafers. The pre vacuum chamber of the equipment adopts a double-layer design, which takes into account both injection and cooling; The pre-treatment system independently developed by the process chamber configuration company can achieve high-quality surface treatment with lower substrate damage; After innovative optimization of wafer grasping, placement, lifting, and temperature control, the transmission system can significantly increase the production capacity of germanium silicon and silicon epitaxial processes. This platform can be configured with a total of 2 pre-processing and 4 EPI process chambers, which can fully meet the production capacity needs of mainstream wafer fabs.
EPI M300 Series
