DC-Plasma Enhanced Chemical Vapor Deposition System

DC-Plasma Enhanced Chemical Vapor Deposition System
Introduction Application Specification Advantage Of Using Nanotechnology Manual And Maintenance Safety And Package
Chemical Vapor Deposition (CVD) is one of the most prominent coating methods whose today's usage covers both experimental and industrial fields. This coating method, in fact, includes a wide variety of configurations which share the common features including: using a gas mixture as a precursor or raw material, using a plasma or heat source for encouraging some sort of reactions between gas species, and eventually predisposing the reaction products to deposit on the substrate. The heating source could be thermal filament, microwaves and/or electrical discharge. 
Plasma Enhanced Chemical Vapor Deposition (PECVD) is a type of CVD methods which presence of a plasma medium affects all CVD processes and enables them to proceed far more effectively at relatively lower temperature compared to the case of not using plasma. This method is mostly used for the production of carbon nanotubes. 
By employing plasma medium, the heating source attempts to decompose the primary gases. The coating mechanism is as follows; a mixture of gases containing carbon precursor (a dilute mixture of methane in hydrogen, for example) is transferred along electrodes so as to decompose into atomic species. Usually, a noble gas is used in conjunction with the active gases in order to increase in total thermal flux of the gas mixture. It also improves the heating rate of substrate and encourages the nucleation of the products on the substrate. 
Todays, PECVD systems usually exploit a collection of several reactors, which enables the user to program the growth process by means of computerized control over the growth parameters such as temperature, pressure, plasma power and the sequence of the gas injection into the system. The evolution of various features in the growing layer depends on the status of the system, which can be quickly switched to a different state. The operating temperature of each reactor can be set between 500 and 850°C for different applications. Apart from standard growth, which is expected from a CVD reactor, these systems can be used as a reactive ion etching unit for hard-to-etch substrate like SiC.
These coatings systems usually need two lines of gas cylinders including Hydrogen and Acetylene. Nevertheless, they can be upgraded by adding one or two more MFCs to include other gases such as Oxygen, NH3 or Argon as a carrier gas. 
  • Deposition of various materials for micro-fabrication processes in various forms, including: monocrystalline, polycrystalline, amorphous, and epitaxial.
  • wear and corrosion resistant coatings on tools, bearings and drills
  • Carbon nanotubes
  • Semiconductor device fabrication
Details of technical specifications are presented in the following Table.
 
PECVD is an unrivaled method for the production of carbon nanostructures, carbon nanotubes and Nano-structure fabrication.
  • Before operating this tool, users must be trained and certified by the manufacturer.
  • Make sure that a substrate is loaded and the chamber lid is closed before starting any processes.
  • Alarm Buzz indicates the system has a condition that may not allow processing. The user should use caution until the cause of the alarm is determined.
  • When the process is completed the user must shut down the system, turn off all gas
  • cylinders and regulators.
  • Hazardous gas cylinders must be placed in their special gas cabinet. A backup nitrogen cylinder is recommended for each hazardous gas. Other gases should be chained to a wall individually and being shielded from the Sun's heat and radiation employed.
  • Never adjust the gas regulators, they are set accordingly for the MFCs, too much pressure can sabotage the MFCs and low pressure can decrease efficiency of the system.
  • For more details on how to use the device, refer to the device catalog and user guide.

·        Precursor gases should be handled with extreme caution:

a) SiH4 and Hydrogen are both highly flammable and explosive. User should be familiar with possible hazards of such gases.


b) NH3 is highly reactive and dangerous liquefied gas which is shipped in special cylinders. Never attempt to use ordinary bottle for this gas, as it is highly corrosive and can convert into undesired species such as hydrogen and nitrogen gases. Use standard bottles.


c) The exposure of the silicon-containing gas (H2) to air would lead to a small torch.

·        Make sure the main pump is continuously purged with nitrogen during the operation to avoid any danger.

·        When you leave the system for any length of time, especially overnight, make sure that the chamber is pumped down and all gas valves including main cylinder valve and regulators are closed.

·        In the event of an emergency, shut off the system power with the emergency power off button on the front of the system. If the machine malfunctions any time during the process, press the red emergency shut-down button.
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