Oxide etch stop techniques for uniform damascene trench depth

Details Oxide etch stop techniques for uniform damascene trench depth Oxide etch stop techniques for uniform damascene trench depth

1997-06-23

2000-05-02

Chaudhari, Chandra

Semiconductor device manufacturing: process

Coating with electrically or thermally conductive material

To form ohmic contact to semiconductive material

438627, 438629, 438637, 438722, 438638, 438639, H01L 214763

Patent

active

060572272

ABSTRACT:
A damascene structure and method for forming such structure. In one embodiment, the damascene structure of the present invention includes a first layer of oxide which is a stochiometric oxide deposited onto a semiconductor substrate. A second layer of oxide which is a non-stochiometric oxide is then deposited onto the semiconductor substrate which is followed by a stochiometric oxide layer. The semiconductor substrate is then masked and etched so as to form vias using a selective etch process which etches the stochiometric oxide and stops etching on the non-stochiometric oxide layer. The etch chemistry is then changed in-situ, allowing the removal of the non-stochiometric oxide at the bottom of the via. The wafer is then re-masked in the pattern of trench interconnect using a selective etch process to selectively etch the layer of stochiometric oxide in the damascene trench down to the layer of non-stochiometric oxide while simultaneously completing the etching of vias. The use of the layer of non-stochiometric oxide as an etch stop gives trenches with a substantially planar bottom surface in a process superior in simplicity and process margin compared to nitride etch stop technologies. Metal is deposited over the semiconductor substrate and is polished so as to remove the metal which overlies the layer of stochiometric oxide so as to form interconnects having uniform depth and contacts. In an alternate embodiment, a damascene structure is formed without the deposition of the first stochiometric oxide layer and etched using an initial non selective etch.

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