Methods of gas distribution in a chemical vapor deposition system

A method of depositing an epitaxial layer on a silicon wafer having a diameter, wherein the wafer is disposed within a processing chamber within a deposition system, the method comprising the steps of:

• introducing a process gas into the system from a gas injecting port, the gas injecting port disposed upstream from the processing chamber;
• flowing the process gas through a gas distribution plate in fluid communication with the gas injecting port and the processing chamber, the gas distribution plate including an inner array of holes and an outer array of holes;
• and
• controlling the gas flow distribution across the substrate surface, the controlling step including selecting at least one orifice-containing plug to be secured within a hole in the gas distribution plate, and securing the selected plug within the hole.