Method and system for dispensing process gas for fabricating a device on a substrate

A method for depositing a material film on a substrate with a process gas, the method comprising the steps of:

• supporting a substrate on a chuck disposed in a reaction chamber proximate a showerhead, the reaction chamber having an exhaust port;
• positioning the chuck to restrict the flow path, wherein the positioning includes substantially aligning the chuck and the exhaust port;
• dispensing process gas from the showerhead to flow over the substrate and out the exhaust port, the process gas for depositing the material on the substrate;
• stopping the dispensing of process gas;
• repositioning the chuck to reduce restriction of the flow path from the showerhead to the exhaust port;
• and
• evacuating residual process gas from the reaction chamber through the exhaust port.

A method for processing a substrate in a reaction chamber comprising:

• supporting the substrate on a chuck disposed in the reaction chamber proximate a showerhead, the reaction chamber having an exhaust port;
• positioning the chuck to restrict the flow path from the showerhead to the exhaust port;
• dispensing process gas from the showerhead to flow over the substrate and out the exhaust port;
• repositioning the chuck to reduce restriction of the flow path from the showerhead to the exhaust port;
• and
• evacuating the process gas from the reaction chamber.