Organic BARC etch process capable of use in the formation of low k dual damascene integrated circuits

Abstract

In some implementations, a method is provided in a plasma reactor for etching a trench in an organic planarization layer of a resist structure comprising a photoresist mask structure over a hardmask masking the organic planarization layer. This may include introducing into the plasma reactor an etchant gas chemistry including N2, H2, and O2 and etching a masked organic planarization layer using a plasma formed from the etchant gas chemistry. This may include etching through the planarization layer to form a trench with a single etch step.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a shows a cut away side view of a substrate showing the forming a via patterned photoresist layer over a low k dielectric layer, the dielectric layer formed over an etch stop layer on a substrate, the substrate having a first trench metal layer.

FIG. 1 b shows a cut away side view of a substrate showing the removal of the photoresist layer after via lithography and showing of the via etch into the low k dielectric layer, stopping at the etch stop layer.

FIG. 1 c shows a cut away side view of a substrate showing the forming the BARC organic planarization layer and SOG layer spun on to fully cover the via.

FIG. 1 d shows a cut away side view of a substrate showing the forming of a trench pattern photoresist layer on the SOG/BARC organic planarization layer.

FIG. 1 e shows a cut away side view of a substrate showing the forming of the BARC organic planarization layer open to recess BARC organic planarization layer into the via after the SOG etch.

FIG. 1 f shows a cut away side view of a substrate showing the forming a trench pattern using BARC organic planarization layer as an etch mask.

FIG. 1 g shows a cut away side view of a substrate showing the stripping of the BARC organic planarization layer on top of the low k dielectric layer and in the via is ashed in situ.

FIG. 1 h shows a cut away side view of a substrate showing the completion of the etch stop layer open process by connecting the dual damascene structure of FIG. 1f to the underlying metal layer.

FIG. 2 shows a cut away side view of the substrate showing FIG. 1d with and optional cap layer between the low k dielectric layer and the BARC organic planarization layer 60.

Claims

1. A method in a plasma reactor of etching an organic planarization layer of a resist structure comprising a photoresist mask structure over a hardmask masking the organic planarization layer, the method comprising: introducing into the plasma reactor an etchant gas chemistry comprising: N2; H2; and O2 ; andetching the masked organic planarization layer using a plasma formed from the etchant gas chemistry.

2. The method of claim 1, wherein etching the organic planarization layer comprises etching through the planarization layer to form a trench in the organic planarization layer.

3. The method of claim 2, wherein etching through the planarization layer to form the trench comprises etching through the planarization layer with a single etch step.

4. The method of claim 2, wherein etching the organic planarization layer comprises etching trenches of disparate cross-sectional areas with a substantially same etch rate.

5. The method of claim 1, wherein introducing the etchant gas chemistry comprises introducing the O2 so as to modulate etch rate microloading during the etching of the organic planarization material.

6. The method of claim 1, wherein introducing comprises introducing the etchant gas chemistry of N2:H2:O2 with a flow ratio of about 10:10:x, respectively, where x is in a range of about one to about three.

7. The method of claim 6, wherein etching the organic planarization layer comprises using a bias power frequency of one of: (a) about 13.56 MHz; or (b) less than about 13.56 MHz.

8. The method of claim 7, wherein etching the organic planarization layer comprises using a bias power of between about 100 Watts to about 1500 Watts.

9. The method of claim 8, wherein etching the organic planarization layer comprises using a plasma source power of between about 300 Watts to about 2000 Watts.

10. The method of claim 1, wherein introducing comprises introducing comprises introducing the etchant gas chemistry of N2:H2:O2 with a flow ratio of about 10:10:1, respectively.

11. The method of claim 10, wherein etching the organic planarization layer comprises using a bias power frequency of about 2 MHz.

12. The method of claim 1, wherein introducing comprises introducing the etchant gas chemistry of N2:H2:O2 with a flow ratio of less than about 10:10:2, respectively.

13. The method of claim 12, wherein etching comprises etching with a bias power frequency of about 13.56 MHz, a bias power of about 800 Watts, and a plasma source power of about 1200 Watts.

14. The method of claim 1, wherein etching the organic planarization layer comprises using a bias power of about 2 MHz.

15. The method of claim 1, wherein etching the organic planarization layer comprises using a bias power of less than about 13.56 MHz.

16. The method of claim 1, wherein etching the organic planarization layer comprises etching away the photoresist mask while etching the organic planarization layer.

17. The method of claim 1, wherein etching the organic planarization layer comprises etching an organic BARC.

18. A method using a plasma reactor for forming a low k damascene integrated circuit device, the method comprising etching a BARC layer of a resist structure comprising a photoresist mask over a hardmask masking the BARC layer, wherein etching the BARC layer comprises: introducing into the plasma reactor an etchant gas chemistry comprising: N2; H2; and O2 with a gas flow ratio of 10:10:x, where x is in a range from about 1 to about 3; andetching the BARC layer using a plasma formed from the etchant gas chemistry to etch through the BARC layer so as to define trenches in the BARC layer.

19. The method of claim 18, wherein etching the organic planarization layer comprises etching trenches of disparate cross-sectional areas with a substantially same etch rate.

20. The method of claim 18, wherein introducing comprises introducing the etchant gas chemistry of N2:H2:O2 with a flow ratio of less than about 10:10:2, respectively, and wherein etching comprises etching with a bias power frequency of about 13.56 MHz, a bias power of about 800 Watts, and a plasma source power of about 1200 Watts.

21. An organic BARC etch method to form low k damascene integrated circuit device using a plasma reactor, the method comprising: providing a semiconductor substrate having an etch stop layer formed over a trench metal layer on the substrate;forming a low k dielectric layer over the etch stop layer;depositing a via patterned photoresist layer over the low k dielectric layer;removing of the photoresist layer and thereafter etching through the low k dielectric layer to the etch stop layer, to form a via opening;forming an organic planarization layer over the via;forming of a trench mask from a photoresist layer and a hardmask layer over the BARC organic planarization layer;introducing an etchant gas mixture comprising: N2; H2; and O2 into the plasma reactor; andetching the BARC organic planarization layer using the etchant mixture to form a trench opening in the BARC organic planarization layer to the via using the etchant gas mixture.

22. The method of claim 21, wherein the etchant gas mixture flow ratio of N2:H2:O2 is about 10:10:x, respectively, where x is in a range from about 1 to about 3.

23. The method of claim 22, wherein the etchant gas mixture flow ratio of N2:H2:O2 is about 10:10:2, respectively.

24. The method of claim 21, wherein the BARC organic planarization layer comprises organic compounds similar in chemical structure to the photoresist layer.

25. The method of claim 21 further comprising: forming a trench pattern in the low k dielectric layer using the etched BARC organic planarization layer as an etch mask;stripping the BARC organic planarization; andopening the etch stop layer to expose the trench metal layer.