Field
Embodiments disclosed herein generally relate to an apparatus and method for controlling the pressure of a processing chamber. More particularly, embodiments herein relate to a dynamic pressure control system.
Description of the Related Art
Substrates, such as semiconductor substrates, can be subjected to an epitaxial growth process to form an epitaxial layer on a surface of the substrate. Conventional epitaxial growth processes include flowing a process gas laterally over the surface of the substrate, and thermally decomposing the process gas on the surface of the substrate in order to deposit the epitaxial layer.
After deposition, process gases remaining in the atmospheric pressure epitaxial growth systems are carried out of the processing chamber to facilitate exhaust through an abatement system. Due to this configuration, the pressure in the processing chamber is affected by the surrounding atmospheric pressure and the exhaust side abatement system (i.e., to remove byproduct clogging), thus there is risk for exhaust byproducts to flow back into the processing chamber by pressure oscillations in the processing chamber. Pressure fluctuations, or pressure spikes, in the processing chamber may result in non-uniform distribution of the processing gas. Therefore, maintaining a constant pressure inside the processing chamber is key for uniform deposition results.
One option for controlling pressure inside the processing chamber is through the use of a vacuum pump. However, atmospheric epitaxial growth systems configured with a vacuum pump can become unsafe due to faster pyrophoric byproduct build up and risk for explosion and fire in exhaust facilities. Therefore, atmospheric epitaxial growth systems are generally not configured with vacuum pump.
Another option for controlling pressure inside the processing chamber includes a pressure control system in the exhaust line to control fluctuations in pressure in atmospheric epitaxial growth systems. Conventional designs can reduce the processing chamber pressure fluctuations to some extent, but conventional designs lack a dynamic range of control.
Thus, there is a need for improved pressure control system processing chambers, and particularly in atmospheric processing chambers.