Point of use solvent mixing for film removal

1 . A method of processing a wafer, the method comprising:

positioning the wafer within a processing chamber, the wafer comprising a film deposited over a surface of the wafer;

rotating the wafer within the processing chamber;

during the processing of the wafer, mixing a first fluid with a second fluid at a mixing ratio at a mixing chamber of a dispense nozzle assembly resulting in a fluid mixture; and

while rotating the wafer, dispensing the fluid mixture from the mixing chamber of the dispense nozzle assembly over an edge portion of the wafer through a dispensing nozzle coupled to the mixing chamber, the dispensing removing a portion of the film on the edge portion of the wafer, while dispensing the fluid mixture, changing the mixing ratio based on a surface topology of the film on the edge portion of the wafer.

2 . The method of claim 1 , further comprising performing a spin-on process to deposit the film over the wafer.

3 . The method of claim 1 , wherein the first fluid has a first fractional concentration in the fluid mixture based on the mixing ratio, wherein a variation of the first fractional concentration in the fluid mixture during the dispensing on the wafer is between 0.1% and 1%.

4 . The method of claim 1 , further comprising selecting the second fluid that has a surface tension higher than that of the first fluid at a processing temperature at which the first fluid and the second fluid are being mixed.

5 . The method of claim 1 , further comprising:

selecting the first fluid that has a surface tension between 10 mN/m and 30 mN/m; and

selecting the second fluid that has a surface tension between 30 mN/m and 60 mN/m.

6 . The method of claim 1 , wherein the first fluid comprises propylene glycol monomethylether (PGME) or propylene glycol monomethylether acetate (PGMEA).

7 . The method of claim 1 , wherein the first fluid comprises 50-80% propylene glycol monomethylether (PGME) and 20-50% propylene glycol monomethylether acetate (PGMEA), and wherein the second fluid comprises γ-butyrolactone (GBL), n-butyl acetate, or ethyl lactate.

8 . A method of processing a wafer, the method comprising:

performing a spin-on process to deposit a photoresist film over the wafer;

rotating the wafer in a processing chamber;

positioning a dispense nozzle assembly over an edge portion of the wafer, the dispense nozzle assembly comprising a mixing chamber and a dispense nozzle;

supplying a first fluid to the mixing chamber through a first supply line at a first flow rate;

supplying a second fluid to the mixing chamber through a second supply line at a second flow rate;

mixing the first fluid with the second fluid at a mixing ratio within the mixing chamber to form a fluid mixture, the mixing ratio being a volumetric ratio of the first fluid to the second fluid; and

while rotating the wafer, dispensing the fluid mixture using the dispense nozzle over an edge portion of the wafer to remove a portion of the photoresist film on the edge portion of the wafer, while dispensing the fluid mixture, changing the mixing ratio by dynamically controlling the first flow rate and the second flow rate independent of each other.

9 . The method of claim 8 , wherein the spin-on process is performed using the first fluid.

10 . The method of claim 8 , wherein the first fluid comprises 50-80% propylene glycol monomethylether (PGME) and 20-50% propylene glycol monomethylether acetate (PGMEA), and wherein the second fluid comprises γ-butyrolactone (GBL), n-butyl acetate, or ethyl lactate.

11 . The method of claim 8 , wherein the photoresist film comprises an edge bead at the edge portion of the wafer prior to dispensing the fluid mixture, and wherein the edge bead is removed during dispensing the fluid mixture.

12 . The method of claim 8 , further comprising, after removing the portion of the photoresist film on the edge portion of the wafer, patterning the photoresist film by exposing the wafer to an ultraviolet (UV) irradiation through a photomask.

13 . A method of processing a wafer, the method comprising:

positioning the wafer within a processing chamber, the wafer comprising a film deposited over a surface of the wafer;

rotating the wafer within the processing chamber;

determining a mixing ratio for a first fluid and a second fluid based on an EBR process recipe, the EBR process recipe comprising at least one parameter selected from a solvent system, a mixing ratio, a spin speed, a dispense rate, a temperature, and a position of a dispensing nozzle;

mixing the first fluid with the second fluid at the determined mixing ratio in a mixing chamber of a dispense nozzle assembly to form a fluid mixture; and

while rotating the wafer, dispensing the fluid mixture from a dispensing nozzle of the dispense nozzle assembly over an edge portion of the wafer to remove a portion of the film on the edge portion of the wafer, the fluid supplied to the dispensing nozzle from the mixing chamber.

14 . The method of claim 13 , wherein the dispensing nozzle is attached to the mixing chamber.

15 . The method of claim 13 , wherein the mixing is performed with laminar flow of the first fluid and the second fluid, and wherein the mixing chamber is a microfluidic mixer.

16 . The method of claim 13 , further comprising:

stopping dispensing the fluid mixture;

after the stopping, characterizing a surface topology of the film at the edge portion of the wafer; and

based on the surface topology, updating the EBR process recipe including the mixing ratio.

17 . The method of claim 13 , wherein determining the mixing ratio based on the EBR process recipe comprises selecting the EBR process recipe from a plurality of different EBR process recipes based on a type of the film.

18 . The method of claim 13 , wherein the first fluid comprises 50-80% propylene glycol monomethylether (PGME) and 20-50% propylene glycol monomethylether acetate (PGMEA), and wherein the second fluid comprises γ-butyrolactone (GBL).