Abstract: A control system used to control a controlled plant includes a main control unit, a first tuning unit, and a second tuning unit. The control system regulated by two weighting parameters of a first multiple and a second multiple, robustness and rapid response are attained, and excess of the output signal the controlled plant generates disappears or approaches zero. The control system has technical features of objective bandwidth, offsetting of low frequency disturbance, and matching of transfer functions. By designing the main control unit, the first tuning unit, and the second tuning unit, regulating the two weighting parameters of the first multiple and the second multiple, and tuning the actual system, the above technical features are obtained.

Abstract: The present invention is a method for forming a shallow trench with tapered profile and round corners for the application of shallow trench isolation (STI). This invention utilizes a multiple-step dry etching process with reduced RF power and increased pressure to etch a shallow trench. This takes advantage of different degree of polymer deposition in different steps by varing the pressure and the RF power. Thus, a shallow trench with tapered profile and round corners is achieved.