Single-Stage Jalapeño heated vacuum valves are specifically designed to withstand high internal temperatures, limiting contaminant buildup and reduce system maintenance. The standard heater for the Jalapeño valve is set to 170°C to achieve a nominal interior temperature of 150°C, but other temperature ranges are optional.
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The heated valves may have up to five different heat zones in the heater controlled by a microprocessor based electronic controller. This eliminates “cold zones” and maintains temperature uniformity in the valve. Minimum temperatures exceed 135°C (see Figure). The valve uses a formed bellows made of 321 stainless steel. Formed bellows are easier to heat and prevent particle entrapment between the convolutions. This increases the valve cycle life.
MKS Heaters use a patented insulation construction that is effective at maintaining heat levels required while remaining safe to touch on the outside. When you touch the outside insulation, your finger acts as a heat sink. The insulation is so effective that the outside temperature of the heater where you are touching falls to 39°C. So the heaters are safe to touch. When you remove your finger, the silicone goes back to 65°C.
Semiconductor CVD and etch processes produce gaseous by-products that can readily be pumped out of the reaction chamber. However, they usually solidify in a vacuum pump line since the line temperature is lower than the reaction chamber. A clogged line means longer down time and lower product yield.
A common process is LPCVD silicon nitride. Since sublimation is temperature driven, use heat to maintain the by-products in the vapor phase and use cooling to intentionally sublimate the vapors in the trap.
Heaters have been used successfully in tungsten and oxide etch systems. Heating helps in TEOS CVD systems where a very tight temperature control is required. Some processes yield unintentional by-products. For example, diammonium hexaflurosilicate (NH4)2SiF6 has been observed in a silicon nitride PECVD process due to the cross chemical reaction of the products formed in the deposition and etching processes. It is a sublimable material that lends itself to heating and cooling strategies. Please consult MKS application engineers for further assistance.