Method of depositing a sculptured copper seed layer
A method of applying a sculptured copper seed layer on a semiconductor feature surface using ion deposition sputtering. A first protective layer of material is deposited on a substrate surface using traditional sputtering or ion deposition sputtering, in combination with sufficiently low substrate bias that a surface onto which the layer is applied is not eroded away or contaminated during deposition of the protective layer. Subsequently, a sculptured second layer of material is applied using ion deposition sputtering at an increased substrate bias, to sculpture a shape from a portion of the first protective layer of material and the second layer of depositing material.
1. A method of sculpturing a copper seed layer on a wafer substrate comprising a plurality of recessed device features having bottoms, sidewalls, and upper openings, the method comprising:
(a) sputter depositing a copper seed layer on the substrate in a physical vapor deposition chamber having a biased wafer substrate support and a biased target, said depositing occurring at a first wafer bias;
(b) sculpturing the copper seed layer by resputtering copper from the bottoms of the recessed device features to the sidewalls of the recessed device feature while simultaneously sputter depositing material from the target onto other regions of the wafer substrate, said resculpturing occurring at a second wafer bias that is substantially stronger than the first wafer bias, whereby the copper seed layer is reshaped to be substantially conformal.
2. A method in accordance with claim 1 , further comprising filling the recessed device features with copper by electroplating.
3. A method in accordance with claim 1 , wherein the sputter depositing occurs in the presence of an inductively coupled RF plasma.
4. A method in accordance with claim 1 , wherein during step (b) there is a net deposition of copper on the substrate surface.
5. A method in accordance with claim 1 , wherein during step (b) there is a minimal net removal of copper from the substrate surface.
6. A method in accordance with claim 1 , wherein, during step (a), there is no excessive build up on the openings of each of the plurality of recessed device features.
7. A method in accordance with claim 1 , wherein, during step (a), the sputter deposition is carried out without substantial resputtering of the depositing bottom coverage in each of the plurality of recessed device features.