Selective etching of silicon dioxide compositions

1. A process for selectively etching a material comprising SiO 2 preferentially to silicon, the method comprising the steps of:

placing a silicon substrate having a layer of a material comprising SiO 2 within a reactor chamber equipped with an energy source;

creating a vacuum within the chamber;

introducing into the reactor chamber a reactive gas mixture comprising a fluorine compound, a polymerizable fluorocarbon, and an inert gas, wherein no oxygen is added to the reactive gas mixture, wherein the fluorine compound is selected from the group consisting of: NF 3 , F 2 , F 2 created in situ, and a mixture of F 2 in an inert gas, and wherein the polymerizable fluorocarbon comprises a compound having the formula C h F i wherein h is a number ranging from 4 to 6 and i is a number ranging from h to 2h+2;

activating the energy source to form a plasma activated reactive etching gas mixture within the chamber; and

selectively etching the material comprising SiO 2 preferentially to the silicon substrate.

2. The process of claim 1 wherein the polymerizable fluorocarbon and the fluorine compound in the reactive gas mixture are present at a ratio of 1:1.

3. The process of claim 1 wherein the material comprising SiO 2 is selected from the group consisting of: SiO 2 and an organosilicate glass.

4. The process of claim 3 wherein the organosilicate glass is selected from the group consisting of phosphorous silicate glass and fluorosilicate glass.

5. The process of claim 4 wherein the material comprising SiO 2 is phosphorous silicate glass.

6. The process of claim 3 wherein the material comprising SiO 2 is substantially SiO 2 .

7. The process of claim 1 wherein the fluorine compound is NF 3 .

8. The process of claim 1 wherein the polymerizable fluorocarbon is selected from the group consisting of: octafluorocyclobutane, octafluorocyclopentene, hexafluorobenzene, hexafluoro-1,3-butadiene and mixtures thereof.

9. The process of claim 8 , wherein the polymerizable fluorocarbon is hexafluoro-1,3-butadiene.

10. A process for selectively etching a material comprising SiO 2 preferentially to silicon, the method comprising the steps of:

placing a silicon substrate having a layer of a material comprising SiO 2 within a reactor chamber equipped with electrodes;

creating a vacuum within the chamber;

introducing into the reactor chamber a reactive gas mixture comprising a fluorine compound, a polymerizable fluorocarbon, and an inert gas, wherein no oxygen is added to the reactive gas mixture, and wherein the fluorine compound is selected from the group consisting of: NF 3 , F 2 , F 2 created in situ, and a mixture of F 2 in an inert gas, and wherein the polymerizable fluorocarbon comprises a compound having the formula C h F i wherein h is a number ranging from 4 to 6 and i is a number ranging from h to 2h+2;

supplying a high frequency electrical energy to the electrodes to form a plasma activated reactive etching gas mixture within the chamber; and

selectively etching the material comprising SiO 2 preferentially to the silicon substrate.

11. The process of claim 10 wherein the ratio of the fluorine compound to the polymerizable fluorocarbon is from 1 to 2.

12. The process of claim 11 wherein the ratio of the fluorine compound to the polymerizable fluorocarbon is from 1 to 1.

13. The process of claim 10 wherein the polymerizable fluorocarbon is selected from the group consisting of: octafluorocyclobutane, octafluorocyclopentene, hexafluorobenzene, hexafluoro-1,3-butadiene and mixtures thereof.

14. The process of claim 13 wherein the polymerizable fluorocarbon is hexafluoro-1,3-butadiene.