Micro-fluid ejection head containing reentrant fluid feed slots
View Patent ↗A method of micro-machining a semiconductor substrate to form through slots therein and substrates made by the method. The method includes providing a dry etching chamber having a platen for holding a semiconductor substrate. During an etching cycle of a dry etch process for the semiconductor substrate, a source power is decreased, a chamber pressure is decreased from a first pressure to a second pressure, and a platen power is increased from a first power to a second power. Through slots in the substrate provided by the method can have a reentrant profile for fluid flow therethrough.
1. A method of micro-machining a substrate to form a through slot therein, the method comprising:
performing an etching cycle of a dry etch process for a substrate held by a platen of a dry etching chamber and, during the etching cycle, decreasing a source power, decreasing a chamber pressure from a first pressure to a second pressure, and increasing a platen power from a first power to a second power, whereby one or more through slots having a reentrant profile are formed in the substrate.
2. The method of claim 1 , farther comprising increasing the platen temperature from below about −19° C. to at least about 20° C.
3. The method of claim 1 , wherein a dry etching plasma for the etching process is derived from a silicon etching source.
4. The method of claim 3 , wherein the silicon etching source comprises sulfur hexafluoride.
5. The method of claim 1 , wherein the source power is decreased during the dry etch process from about 2500 Watts to about 2000 Watts.
6. The method of claim 5 , wherein the first power ranges from about 150 to about 200 Watts and wherein the second power ranges from about 200 to about 300 Watts.
7. The method of claim 6 , wherein the first pressure ranges from about 100 to about 150 milliTorr and the second pressure ranges from about 30 to about 60 milliTorr.
8. The method of claim 7 , farther comprising increasing the platen temperature from below about −19° C. to at least about 20° C.
9. In a deep reactive ion etching process for etching a substrate to form one or more reentrant fluid flow slots therein, the improvement comprising:
decreasing a source power during etching cycle steps of the etching process;
decreasing a chamber pressure from a first pressure to a second pressure during etching cycle steps of the etching process; and
increasing a platen power from a first power to a second power during etching cycle steps of the process.
10. The improvement of claim 9 , further comprising increasing a platen temperature during at least passivating cycle steps of the etching process from a first temperature to a second temperature.
11. The improvement of claim 9 , wherein the source power is decreased from about 2500 Watts to about 2000 Watts.
12. The improvement of claim 9 , further comprising increasing the platen temperature from below about −19° C. to at least about 20° C.
13. The improvement of claim 9 , wherein a deep reactive ion etching plasma is derived from a silicon etching source.
14. The improvement of claim 13 , wherein the silicon etching source comprises sulfur hexafluoride.
15. The improvement of claim 9 , further comprising mechanically thinning the substrate to provide a substrate having a thickness ranging from about 200 to about 450 microns.
16. The improvement of claim 15 , wherein the substrate is thinned by grinding a backside surface area of the substrate.