Abstract: An oxide etching method using low-medium density plasma includes a first etching step to pre-etch the oxide layer with low etching selectivity etchant to pre-form a contact opening and a monitoring opening. The low etching selectivity etchant can also etch the photoresist layer and the photoresist reaction residue. Then, a second etching with high etching selectivity on the oxide is performed to completely form the contact opening with a SAC property and the monitoring opening. The openings expose the substrate.

Abstract: A computer system having a computer model of a Finite State Machine (FSM). The computer system includes a processor coupled to receive and manipulate the computer model, and a memory. The memory includes a computer model. The computer model includes, a first set of inputs, a first set of delayed inputs, a first set of outputs and a first set of delayed outputs. The computer model has a first output of the first set of outputs corresponding to a first input of the first set of inputs, a first delayed input of the first set of inputs and a first delayed output of the first set of delayed outputs.