Valves control system, multiplexed

Fig. 16 Multiplexed valve control system [59]. (a) Overview of 2 (256) microvalve array, (b) Operating principle of multiplexed valve-control system...

Figure 4 shows schematically the STS Multiplex ICP etching system. The source plasma is generated by an inductively coupled coil supplied by a 1-3 kW 13.56 MHz RF generator. Another 13.56 MHz generator is used to power the platen electrode which allows independent control of the bias potential of the wafer relative to the source plasma. The wafer temperature is maintained at typically less than 80 C through temperature-controlled, pressurized helium supplied to the back of the wafer. Wafers may be either mechanically or electrostatically clamped to the platen electrode. Typical base pressures are in the 10 torr range. The system is equipped with an automatic pressure control valve which can operate in one of two modes. In fixed automatic pressure control (APC) mode, the APC position remains constant, and the chamber pressure is a function of gas flows and RF powers. In automatic APC mode, the APC valve adjusts to maintain the chamber pressure at a constant value. The tool has been developed... 

The SYMPHONY/Multiplex (Figure 8), introduced in 1993, is a batch (Boc/Fmoc peptide synthesizer with 12 independent reaction vessels (49). The key component is the patented matrix valve system that enables different solutions to be transferred to each of the 12 reactors simultaneously. This feature allows the assembly of 12 different peptides under optimal conditions for each sequence with regard to scales and customized coupling reactions. Solution flow is controlled via chemically resistant membrane valves arranged to provide a matrix system with common solution ports but separate delivery lines for each reaction vessel. A combination of gas pressure and an external vacuum pump operates the valve system. Solution transfer is achieved by nitrogen pressure. 

The block diagram of Micro-TEIMAC system is shown in Fig. 1. It comprises of i) 8086 microprocessor-based microcomputer, ii) Precision 4 1/2-digit industrial grade thermometer, iii) Low offset 24-point scanner multiplexer, (iv) Digital indicating end monitoring panel, v) 24-channel controller, vi) Control status and deviation indicator, vii) Stepper motor operated low torque valve, and viii) Electro-pneumatically controlled high torque valve... 

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