Water-cooled quartz walls

Cold wall reactors are the other major category of CVD reactors. In such systems, the substrates are heated but the walls are cooled. Figure 9 shows an example of a cold wall rotating disk CVD reactor.This system has water-cooled quartz walls, with a rotating holder for (silicon or compound semiconductor) wafers that is resistively heated from below. Other commercial cold-wall reactors include lamp heated single-wafer reactors that are widely used in microelectronics fabrication, and inductively heated horizontal flow reactors. Cold-wall reactors are often run at relatively high pressures, several hundred torr to atmospheric total... 

W) through a double-walled water-cooled quartz G.jn > 250 nm) immersion well (Figure 3.9) for 5h. The reaction mixture was then washed with ice-cold ammonia solution, dried and concentrated under reduced pressure. The residual oil was purified by column chromatography to give a mixture of the isomers 114. 

Figure 7-95. Electrodeless RF plasma reactor for manganese oxide (MnO) production from rhodonite (MnSiOs) (1) inductor of the RF generator (2) Tesla coil (3) quartz reactor walls (4) brass pipe (5) water-cooled pipe.

Cold-wall type CVD set-up (1) water-cooled vacuum chamber (2), (7) quartz glass windows (3), (4) gas inlets (5) pressure gauge (6) water-cooled copper electrode (8) graphite heater (substrate) (9) graphite socket (10), (11) gas outlets. 

A copper cylinder, equipped at the bottom with a detachable burner, is used as the reaction vessel. Two observation tubes, each consistii of a 30-cm.-long copper tube with a quartz window (rubber gasket seal), allow observation of the flame. The vessel is wrapped with towels or muslin bandages to permit thorough wetting of the apparatus wall by the cooling water running over it. 

The alloys were prepared by the direct fusion together of tellurium (vacuum-sublimed twice), In-0 grade indium, and V-4 grade arsenic. The components were fused together in quartz ampoules evacuated to 10" mm Hg in a furnace which was shaken periodically or rotated. The synthesis temperature was 970-980°C. The ampoules containing the melts were maintained at the maximum temperature for two hours, then cooled at a rate of 50-100 deg/h. Some of the melts were also quenched from the liquid state in water. In all cases, there was virtually no sublimate on the walls of the ampoules after synthesis. 

A low pressure UV lamp (11W, Amax = 253.7 mn) was positioned vertically inside the quartz glass cylinder in the middle of the photocatalytic zone. Air was supplied from a porous titanium plate directly below the membrane module. The purpose of the aeration was to provide dissolved oxygen for photoreaction, to fluidize the IIO2 particles and to create sufficient turbulence along the membrane surface. The reaction temperature was controlled by using cooling water. Permeate was withdrawn from the system with the help of a suction pump. A water level sensor was used to maintain a constant level of solution in the reactor. Additionally, the exterior wall of the reactor was covered with a reflecting aluminum foil to improve the efficiency of UV utilization. 

---