Silicon nitride is used as a mask when etching silicon wafers as part of the semiconductor manufacturing process. Before the silicon wafer goes to the next fabrication steps, the silicon nitride needs to be removed from the wafer surface using a solution of DI water and phosphoric acid.
To optimize the silicon nitride wet etching process, the phosphoric acid solution is kept at a high temperature. This means some of the DI water boils off as steam and must be replaced. Adding water to the phosphoric acid is extremely dangerous as it can explode. Keeping the solution at a constant temperature is essential for accurate control of the stripping process.
Modutek has made significant improvements to both the safety and the control of the nitride wet etching process with its Nb series silicon nitride wet etching baths. Here, the heater that boils the solution is always switched on, which leads to the solution being heated up to the boiling point and further heating will not increase the temperature, just the boiling rate.
Just in case the temperature increases, a thermocouple in Modutek's bath gives the signal that the DI water should be added. Then, the DI water is added slowly to the boiling solution (since the acid boils rapidly) to make sure that it's mixed in immediately and doesn't form a water film on the solution's surface. If the water is added to the solution too quickly, the water film will form and mix itself with the acid, which leads to a very strong reaction and an explosion is possible.
This control strategy employed in Modutek’s system ensures the temperature of the solution is always maintained at its boiling point.Modutek’s silicon nitride wet etching baths also have additional safety features which ensure that no water is added if the solution is not boiling. Using its advanced control system with additional safety interlocks, Modutek has improved the accuracy, control and safety of the silicon nitride wet etching process.
To optimize the silicon nitride wet etching process, the phosphoric acid solution is kept at a high temperature. This means some of the DI water boils off as steam and must be replaced. Adding water to the phosphoric acid is extremely dangerous as it can explode. Keeping the solution at a constant temperature is essential for accurate control of the stripping process.
Modutek has made significant improvements to both the safety and the control of the nitride wet etching process with its Nb series silicon nitride wet etching baths. Here, the heater that boils the solution is always switched on, which leads to the solution being heated up to the boiling point and further heating will not increase the temperature, just the boiling rate.
Just in case the temperature increases, a thermocouple in Modutek's bath gives the signal that the DI water should be added. Then, the DI water is added slowly to the boiling solution (since the acid boils rapidly) to make sure that it's mixed in immediately and doesn't form a water film on the solution's surface. If the water is added to the solution too quickly, the water film will form and mix itself with the acid, which leads to a very strong reaction and an explosion is possible.
This control strategy employed in Modutek’s system ensures the temperature of the solution is always maintained at its boiling point.Modutek’s silicon nitride wet etching baths also have additional safety features which ensure that no water is added if the solution is not boiling. Using its advanced control system with additional safety interlocks, Modutek has improved the accuracy, control and safety of the silicon nitride wet etching process.
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