DETERMINING THE PARAMETERS OF A DYNAMIC MODEL FOR THE GROWTH OF SEMICONDUCTOR SILICON CRYSTALS

摘要

Modern technological units used to grow silicon monocrystals have been equipped with SAU [Automatic Control System] which includes microcomputers. A basic function of the SAU is to stabilize the geometric characteristics of crystals. This task is rather complex because the item under control is unstable, unstationary and has a non-minimal phase. The SAU exercises multichannel control with a PID-law in each regulating circuit; the parameters for the multichannel regulator will not change over the course of the entire growth process even though it is evident that automatic fine tuning would have a favorable effect on the control quality. By introducing a microcomputer to me SAU, improvements can be made in the quality of crystal shape-formation because more effective control methods are available which are based on processing empirical data covering process parameters. Intensifying the parameters under normal conditions can be useful both for technologists as well as when production is being automated.