METHOD OF REMOVING PHOTORESIST AND ETCH-RESIDUES FROM VIAS
A method of photoresist removal with concomitant de-veiling is provided. The method employs a plasma formed from a gas chemistry comprising O 2 , NH 3 and a fluorine-containing gas, such as CF 4 . The method is particularly suitable for use in MEMS fabrication processes, such as inkjet printhead fabrication.
1 . A method of removing photoresist from a substrate, said method employing a plasma formed from a gas chemistry comprising: O 2 , NH 3 and a fluorine-containing gas.
2 . The method of claim 1 , wherein said method concomitantly de-veils etched vias in said substrate.
3 . The method of claim 1 , wherein said fluorine-containing gas is CF 4 .
4 . The method of claim 1 , wherein said fluorine-containing gas is present in said gas chemistry in a concentration of less than 5% by volume.
5 . The method of claim 1 , wherein said fluorine-containing gas is present in said gas chemistry in a concentration of less than 3% by volume.
6 . The method of claim 1 , wherein a ratio of O 2 :NH 3 is in the range of 20:1 to 5:1.
7 . The method of claim 1 , wherein a ratio of O 2 :CF 4 is in the range of 40:1 to 20:1.
8 . The method of claim 1 , wherein the gas chemistry consists only of O 2 , NH 3 and CF 4 .
9 . The method of claim 1 , wherein a rate of photoresist removal is at least 20% greater than a rate of photoresist removal using an O 2 plasma.
10 . The method of claim 1 , wherein said photoresist is hardbaked photoresist.
11 . The method of claim 1 , wherein said photoresist is UV-cured photoresist.
12 . The method of claim 1 , wherein said photoresist has a thickness of at least 5 microns.
13 . The method of claim 1 , wherein said substrate is attached to a chuck, and said chuck is cooled to a temperature in the range of −5 to −30° C.
14 . The method of claim 1 , wherein said method is a step of a MEMS fabrication process.
15 . The method of claim 1 , wherein said method is a step of a printhead fabrication process.
16 . The method of claim 15 , wherein said photoresist is contained in at least one of: inkjet nozzle chambers and ink supply channels.
17 . The method of claim 15 , wherein said photoresist is a protective coating for inkjet nozzle assemblies and/or a mask for an anisotropic deep reactive ion etching (DRIE) process.
18 . A method of fabricating an inkjet printhead, said method comprising the steps of:
forming inkjet nozzle chambers on a frontside of a wafer substrate, each nozzle chamber having a corresponding ink inlet plugged with photoresist;
etching ink supply channels from a backside of said wafer substrate to meet with said ink inlets plugged with photoresist; and
removing at least some of said photoresist and concomitantly de-veiling said ink supply channels by subjecting said backside to a first plasma formed from a first gas chemistry comprising: O 2 , NH 3 and a fluorine-containing gas.
19 . The method of claim 18 comprising the further step of:
removing further photoresist by subjecting said frontside to a second plasma formed from a second gas chemistry comprising: O 2 and NH 3 .
20 . The method of claim 18 , wherein said second gas chemistry comprises: O 2 , NH 3 and a fluorine-containing gas.