Design of Germanium Single Crystal Workshop
Germanium single crystal is an important basic material for optoelectronic components such as silicon light transistors, optical fibers, and laser lighting. Germanium single crystal production process is complex and high value-added, which reflects EPI,CVD and EVAL steps,technological parameters as well as environmental and safety protection measures. In terms of production and operation, Germanium single crystal is different from other general semiconductor materials. Therefore, in the design of a germanium single crystal workshop, it is necessary to consider comprehensively the specific conditions of germanium crystal, the characteristics of the process, and the requirements of informed production.
1 Germanium Crystal Characteristics
Germanium crystal is a metal-containing single crystal semiconductor, which has large resistivity, high melting point, great mechanical strength, small temperature coefficient and excellent optical properties. Different from other general semiconductor materials. Germanium crystal is suitable for use at room temperature or above, so it is easy to be oxidized and moisture absorption when handling. The chips produced by germanium crystal maybe harmful to human body, such as skin and mucous membrane, if it contacts with human body, it should be immediately washed off with water or soap. Therefore, when germanium single crystal is produced and operated, we should pay attention to its special characteristics, and take necessary safety measures.
2 Ethylene Propylene Implantation (EPI) Process
EPI process is a kind of physical method used to manufacture high resistivity Ge single crystal. In the process, the seed crystal is fixed on a single axis rotating mechanism and implanted into the polycrystalline germanium material containing dopants by the ethylene propylene implanter to form a single crystal along the [111] direction of crystallization. In the EPI process, the temperature of the polycrystalline germanium material should be kept higher than the melting point of germanium (938℃). To maintain the crystallization temperature, an intensive shield gas heating device needs to be built.
3 Design Requirements
In order to ensure reliable process parameters, the design requirements for the workshop should comply with the following aspects:
A. The geometry of the workshop should be reasonably designed. The positioning, operation, maintenance and other operations of each station should be flexibly arranged, and the distances between the devices should be as short as possible. At the same time, the buffer space can be increased to facilitate process adjustment.
B. In order to better guide the heat source and medium of the equipment, the S-type geometry of the workshop should be adopted, the workshop should be sealed, and the medium should be set at the equipment position to improve the efficiency;
C. The workshop must reduce the influence of external moisture and dust on the process, and provide a dust-free, low-humidity, low-temperature and low-noise work environment for germanium single crystal production;
D. The workshop should be well ventilated, with sufficient air exchange rates and other process guidance systems;
E. The workshop should be equipped with an alarm system and automatic control system;
F. Special lighting should be provided to make sure that the operators can clearly read the instrumentation during production process.
3.1 Safety Measures
When designing the germanium single crystal workshop, special attention should be paid to safety issues. The workshop should be equipped with more prevention and control facilities and automatic suppression systems. The following safety considerations should be taken into account in the workshop design:
A. The entrance and exit of personnel should be equipped with an emergency stop switch. In the event of a fire, all power sources in the workshop will be cut off to ensure the safety of personnel;
B. The workshop should be designed with automatic fire extinguishing system, with the fire extinguishing agent installed in different positions;
C. The workshop should be equipped with emergency evacuation routes, rescue personnel and fire-fighting equipment;
D. Except for specific operations, personnel should wear complete safety protection equipment such as protection masks and glasses;
E. Operating personnel should be trained on safety knowledge related to production operations and use safety measures to ensure safe operations.
4 Summary
The design of germanium single crystal workshop must ensure the safe, efficient and environmentally friendly production. Considering the special characteristics of germanium single crystal, we should consider the process, product, environment and safety precautions when designing the workshop. The production process of germanium single crystal is complex and involves a series of delicate operations, and safety issues should be taken into consideration when designing the workshop. By taking into account all aspects of the design, we can build a safe, efficient and environmental-friendly single crystal workshop.
