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Economic OEM Mass Flow Controller for PVD Applications

Jun 01, 2012

Those of you who work in the solar energy and semiconductor industry will be familiar with physical vapor deposition (PVD) or sputtering that is commonly used for creating films of material on a substrate in the solar energy and semiconductor industry.

In the PVD process, a negatively charged electrode is slowly disintegrated by molecular bombardment. The PVD medium is typically argon because this gas generates sufficient momentum to free atoms from the target. In a vacuum environment, these free target atoms deposit themselves on the surface of the material and form the desired coating or plating.

Maintaining a specified gas mass flow rate to the vacuum chamber is critical during the PVD process. Typically, vacuum pumping stations require a throttle valve or orifice-limiting device to control the pump’s output when the PVD gas is introduced. This method is extremely pressure sensitive and can result in inefficient gas delivery and poor product quality.

PVD presents two critical challenges in the manufacturing of films used in solar photovoltaics. The first is the use of high vacuum. Since there is so little pressure drop to work with, PVD processes require flow control devices that are relatively insensitive to the absolute pressure in the chamber. This rules out devices like orifice plates that require a large pressure difference to operate efficiently.

The second issue is maintaining very precise gas mass flow rates. Since the layers deposited by PVD processes can, in many cases, be only molecules thick, very precise delivery methods of the doping gases are required.

At Sierra Instruments, we are in tune with these challenges and offer a solution for both: the Smart Trak® 50 digital flow meter. The instrument automatically compensates for changes in system pressure (vacuum pump fluctuations) or loss of pressure from the gas source (cylinder depletion). The SmartTrak 50 delivers a precisely controlled gas mass flow rate to the vacuum chamber to maintain high quality end-product.

Whether you’re a machine builder, systems integrator or end-user, our family of economical/OEM mass flowmeters and mass flow controllers provide a comprehensive mix of flow solutions for nearly every application type.

Mark Blackbourn, Engineer
Written By:
Mark Blackbourn, Engineer
Sierra Instruments

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