Pressure control strategies to provide uniform treatment streams in the manufacture of microelectronic devices
View Patent ↗The present invention provides techniques to more accurately control the process performance of treatments in which microelectronic substrates are treated by pressurized fluids that are sprayed onto the substrates in a vacuum process chamber. control strategies are used that adjust mass flow rate responsive to pressure readings in order to hold the pressure of a pressurized feed constant. In these embodiments, the mass flow rate will tend to vary in order to maintain pressure uniformity.
1. An apparatus, comprising:
a) a sub-atmospheric process chamber comprising an interior volume having a chamber vacuum pressure;
b) a substrate chuck disposed within the interior volume; and
c) a fluid supply line that delivers a pressurized fluid to the interior volume at a controllable flow rate and a controllable pressure, the fluid supply line comprising:
i) a flow control device that controls the flow rate of the fluid through the supply line; and
ii) a flow restriction device through which the fluid is dispensed into the process chamber from the supply line; and
iii) a pressure transducer that measures the controllable pressure of the pressurized fluid in the supply line;
d) a vacuum pump coupled to the process chamber in a manner effective to control the chamber vacuum pressure; and
e) a control system that includes the flow control device and the pressure transducer and that is configured to adjust the flow rate of the pressurized fluid in the supply line as a function of pressure readings obtained by the pressure transducer in order to control the pressure of the pressurized fluid in the supply line at a desired pressure setpoint.
2. The apparatus of claim 1 , wherein the flow restriction device comprises a fluid expansion nozzle comprising:
an inlet that receives the incoming pressurized fluid, said inlet having an inlet diameter between 0.1 mm and 4 mm;
an outlet through which the incoming pressurized fluid is sprayed into the process chamber, said outlet having an outlet diameter in the range from 0.1 mm to 6 mm; and
a throat between the inlet and the outlet, said throat having a throat diameter between 0.1 mm and 4 mm.
3. The apparatus of claim 1 , wherein the flow restriction device comprises an gas expansion nozzle comprising:
an inlet that receives the incoming pressurized fluid, said inlet having an inlet diameter between 0.1 mm and 4 mm; and
an outlet through which the incoming pressurized fluid is dispensed into the process chamber, said outlet having an outlet diameter in the range from 0.1 mm to 6 mm.
4. The apparatus of claim 1 , wherein the flow control device comprises a mass flow controller to adjust the pressure of the pressurized fluid in the supply line based, at least in part, on a difference between the pressure readings obtained by the pressure transducer and the desired pressure setpoint.
5. The apparatus of claim 1 , wherein the flow control device comprises a needle valve, a pinch valve, a diaphragm valve, and/or a variable control valve controlled by a process controller to control the pressure of the pressurized fluid in the supply line based, at least in part, on a difference between the pressure readings obtained by the pressure transducer and the desired pressure setpoint.
6. The apparatus of claim 1 , wherein the flow control device comprises a variable electric valve or a variable pneumatic valve controlled to adjust the pressure of the pressurized fluid in the supply line based, at least in part, on a difference between the pressure readings obtained by the pressure transducer and the desired pressure setpoint.
7. The apparatus of claim 1 , wherein the flow control device comprises a dome-loaded pressure regulator that is controlled by a process controller, where the dome-loaded pressure regulator is adjusted by a pneumatic gas pressure applied to the dome-loaded pressure regulator.
8. The apparatus of claim 1 , wherein the dome-loaded pressure regulator is electrically coupled to a process controller via an electro-pneumatic transducer.
9. The apparatus of claim 1 , further comprising a cooling system disposed on the supply line between the flow control device and the flow restriction device.