Ultrahigh Vacuum, Chemical Vapor Deposition

Application ID: 21711

Chemical vapor deposition (CVD) is a process often used in the semiconductor industry to grow layers of high-purity solid material on top of a wafer substrate. CVD is achieved using many different techniques and across a range of pressures from atmospheric to ultrahigh vacuum (UHV/CVD).

UHV/CVD is performed at pressures below 10-6 Pa (10-8 Torr), so gas transport is achieved by molecular flow and lacks any hydrodynamic effects such as boundary layers. In addition, there is also no gas-phase chemistry involved due to the low frequency of molecular collisions, so growth rate will be determined by the number density of species and surface molecular decomposition processes.

This model uses multiple species, free molecular flow to model the growth of silicon wafers. The effect from several pumping curves are explored.

This model example illustrates applications of this type that would nominally be built using the following products: