CO/CU selective wet etchant

Abstract

The disclosed and claimed subject matter relates to wet etchants that exhibit high copper and cobalt etch rates, wherein the etch rate ratio between two metals can vary. The wet etchant has a composition comprising a formulation consisting of: at least one alkanolamine having at least two carbon atoms, at least one amino substituent and at least one hydroxyl substituent, wherein the amino and hydroxyl substituents are attached to two different carbon atoms; at least one pH adjusting agent for adjusting the pH of the formulation to between about 9 and about 12; at least one chelating agent; and water.

Description

[0001] background technical field [0002] The disclosed and claimed subject matter relates to wet etchants. In particular, the disclosed and claimed subject matter relates to wet etchants that exhibit high copper and cobalt etch rates, wherein the etch rate ratio between the two metals can be varied. Background technique [0003] Co / Cu composite interconnect systems are widely used in BEOL of advanced IC devices due to their good EM and TDDB (time-dependent dielectric breakdown) reliability. For the next advanced technology devices, Cu and Co recesses become more important for fully self-aligned via designs. However, conventional high-rate copper wet etchants cannot simultaneously achieve high cobalt etch rates due to (i) differences in the chemical properties of copper and cobalt and (ii) galvanic corrosion effects between the two metals. [0004] For example, it has been described (see Journal of applied electrochemistry, 33:403-10 (2003)) that monoethanolamine-based fo...

AI Technical Summary

Problems solved by technology

Although conventional copper wet etchants provide high etch rates at high pH, ​​due to the formation of inert Co(OH) 2 layer, the cobalt etch rate is very low at high pH

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