Chemical planarization
Examples are disclosed that relate to planarizing substrates without use of an abrasive. One example provides a method of chemically planarizing a substrate, the method comprising introducing an abrasive-free planarization solution onto a porous pad, contacting the substrate with the porous pad while moving the porous pad and substrate relative to one another such that higher portions of the substrate contact the porous pad and lower portions of the substrate do not contact the porous pad, and removing material from the higher portions of the substrate via contact with the porous pad to reduce a height of the higher portions of the substrate relative to the lower portions of the substrate.
1. A porous pad for performing abrasive-free chemical planarization of a substrate, the porous pad comprising:
a first polymer layer configured to contact the substrate during the abrasive-free chemical planarization, the first polymer layer lacking an abrasive and comprising a first, larger average pore size within a range of 10 to 1000 nanometers and a first, lesser thickness, the first, lesser thickness being within a range of 0.1 to 5 microns;
a second polymer layer positioned on an opposite side of the first polymer layer as a substrate-contacting side of the first polymer layer, the second polymer layer lacking an abrasive and comprising a second, smaller average pore size within a range of 5 to 500 nm and a second, greater thickness; and
an abrasive free planarization chemistry disposed within pores of the first polymer layer and pores of the second polymer layer, the abrasive-free planarization chemistry comprising a functionalizing compound bonded to a surface of pores of the porous pad, the functionalizing compound comprising one or more of a complexing agent or a hydrolyzing agent.
2. The porous pad of claim 1 , wherein the first polymer layer comprises a polymeric asymmetric membrane of hardness 60-90 shore A or 30-90 shore D.
3. The porous pad of claim 1 , further comprising a sub-layer to which the porous pad is joined.
4. The porous pad of claim 1 , wherein the functionalizing compound comprises a hydrolyzing agent comprising one or more of poly(diallyldimethylammonium chloride), poly(dimethylamine-co-epichlorohydrin-co-ethylenediamine), poly(allylamine), and poly(ethylene imine).
5. The porous pad of claim 1 , wherein the one or more of the first polymer layer and the second polymer layer comprises one or more of a polyurethane, polycarbonate, polyacrylate, polysulfone, polyester, polyethersulfone, polyvinylidene fluoride, and polyacrylonitrile.
6. The porous pad of claim 1 , wherein the first and second polymer layers are configured to allow an abrasive-free chemical planarization solution to flow through and thereby be distributed throughout the porous pad.
7. The porous pad of claim 1 , wherein the functionalizing compound comprises one or more of a copper complexing agent, a cobalt complexing agent, a tantalum complexing agent, and a titanium complexing agent.
8. The porous pad of claim 1 , wherein the functionalizing compound comprises a chelating agent.
9. The porous pad of claim 1 , wherein the functionalizing compound is adsorbed onto one or more of the first polymer layer or the second polymer layer.
10. The porous pad of claim 1 , wherein the functionalizing compound is bonded via a crosslinked co-polymer precipitated onto one or more of the first polymer layer or the second polymer layer.
11. The porous pad of claim 1 , wherein the functionalizing compound is covalently bonded to one or more of the first polymer layer or the second polymer layer.
12. The porous pad of claim 8 , wherein the chelating agent comprises one or more of poly(acrylic acid), ethylenediaminetetraacetic acid (EDTA), sulfosalicylic acid, napthol (PAN), dithizone, a organophosphorus acid ester, polyethylene glycol, an amine, and thioxin.
13. The porous pad of claim 1 , wherein the second, greater thickness is within a range of 5 microns to 3 mm.