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Silicon Nitride Etch Bath

NB Series Silicon Nitride Etch Bath
Engineered to provide unparalleled process control, safety, and consistency in Silicon Nitride etching
  • Flame-polished 99.995% pure quartz vessel—ideal for ultra-pure chemistries
  • PVDF or PTFE refluxor condenses vapors before they can escape from the bath, making it perfect for low flash-point chemicals or high-temperature operations
  • Remote metering and deionized (DI) water injection system compensates for boil-off to maintain consistent chemistry temperature and phosphoric acid/water ratio
  • Includes etch-foil resistance heater and vapor thermocouple (for chemical boiling control)
  • Operating temperature is 30°C - 180°C (86°F - 356°F)
  • One-year warranty
NB Series Silicon Nitride Etch Bath The Nb Series Silicon Nitride Etch Bath is ideal for etching silicon nitride layers in a heated process solution of phosphoric acid and DI water. As with other semiconductor-grade quartz baths, it resists damage from caustic chemicals and maintains dependable heat uniformity.

Nb Series heats the acid/water process solution to the process set point. Rather than injecting water once the set point is reached, it monitors the temperatures both of the solution and the vapor. As the process solution heats beyond its set point, DI water is injected into the process solution to replace water lost through vaporization. The water is gradually mixed with the boiling chemical, preventing harmful reactions.

If either temperature setting is not reached, as in the case of an open cover, a thermocouple communicates with an interlock to prevent water injection; solenoid valve power is cut. When temperatures are out of specification, it's an indicator that the chemical/water ratio is off. Once the level reaches set-point, the interlock is reset.

NB Series Silicon Nitride Etch Bath Looking down inside an installed Silicon Nitride Etch Bath.
These, and other, safety precautions guard against circumstances such as bumping: layering the DI water on top of the acid. You benefit from excellent bath-to-batch consistency and a high degree of operator safety. A keypad allows programming of temperature and duration, and resists damage from chemicals. A variety of status indicators visually and audibly communicate messages to operators, including: liquid levels, target temperature, and time settings.

Bath works on 208 VAC, 50/60 Hz, single-phase, 15 amps. Process vessel is made of flame-polished virgin quartz; housing is flame-retardant, stress-relieved polypropylene (UL-94, V-O rated), and thermocouples are J-type, covered with Teflon®.

Options for the Silicon Nitride Etch Bath include pneumatically actuated auto cover, aspirator valve system, Teflon® gravity drain, remote operation time switches, C1815a process controller and RS232 communication.

Terra offers a comprehensive range of constant temperature baths, etching baths, and dump rinsers to meet other size and temperature requirements. Call a Product Specialist to discuss your application.

Nitride Etch Baths installed in:
Manual Wafer Processing Bench
Semi-Automated Wafer Processing Bench
Fully Automated Wafer Processing Bench
Processing Modules
Model below accommodates a single wafer cassett. Call Terra for other sizes.
Installation charged separately; will vary based on the complexity of the processing station.

Cat. # Price
Nb Series Nitride Etch bath, 6" cassette 7018-30 $ 14,003
Corresponding Controls
Heat Cool Liquid
Timer Over/
Cat. # Price
C1815aLSS x
x x

x 7018-36 $ 2,473
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