METHOD AND APPARATUS FOR PRESSURE AND PLASMA CONTROL DURING TRANSITIONS USED TO CREATE GRADED INTERFACES BY MULTI-STEP PECVD DEPOSITION

A method and apparatus are provided for a graded PECVD process that continuously modulates a set of flow and pressure conditions while the plasma power is turned on and a film is being deposited. A feedback mechanism specific to a give deposition recipe is used to generate, optimize and maintain a dynamic profile for a first input process parameter that produces a desired dynamic profile for a first output process parameter. An iterative approach produces a gradually converging series of dynamic profiles of an input profile parameter, which eventually succeeds in producing the desired dynamic profile for the first output process parameter of the graded PECVD process.