Conductive connection structure with stress reduction arrangement for a semiconductor device, and related fabrication method
A semiconductor device disclosed herein includes a conductive connection structure having a stepped profile that serves as a stress relief feature. The conductive connection structure includes a stress buffer arrangement for a contact pad. The stress buffer arrangement has a stepped via that terminates at the contact pad, and the stepped via has a plurality of inwardly sloped and concentric sections in a stacked orientation. The connection structure also includes underbump metallization overlying at least a portion of the contact pad and lining the stepped via, and a conductive connection element coupled to the underbump metallization. The conductive connection element fills the lined recess.
1. A method of fabricating a semiconductor device, the method comprising:
forming a semiconductor device structure comprising a contact pad;
forming a layer of passivation material overlying the semiconductor device structure and overlying the contact pad;
forming a layer of first stress buffering material overlying the layer of passivation material;
exposing a portion of the layer of first stress buffering material, resulting in exposed and undeveloped first stress buffering material;
forming a layer of second stress buffering material overlying the exposed and undeveloped first stress buffering material;
exposing a portion of the layer of second stress buffering material, resulting in exposed and undeveloped second stress buffering material;
concurrently developing the exposed and undeveloped second stress buffering material and the exposed and undeveloped first stress buffering material to remove some of the second stress buffering material and some of the first stress buffering material to expose a portion of the layer of passivation material, resulting in a recess having a stepped cross-sectional profile;
selectively etching the layer of passivation material using the first stress buffering material, the second stress buffering material, and the recess as an etch mask, to expose at least a portion of the contact pad; and
thereafter forming a conductive connection element overlying the recess.
2. The method of claim 1 , wherein forming a conductive connection element comprises:
lining the recess with underbump metallization, resulting in a lined recess; and
forming conductive material in the lined recess.
3. The method of claim 1 , wherein concurrently developing comprises:
removing some of the second stress buffering material to create an inwardly sloped recess sidewall in the layer of second stress buffering material; and
removing some of the first stress buffering material to create an inwardly sloped recess sidewall in the layer of first stress buffering material;
wherein the inwardly sloped recess sidewall in the layer of second stress buffering material and the inwardly sloped recess sidewall in the layer of first stress buffering material are discontinuous.
4. The method of claim 1 , wherein concurrently developing comprises:
removing some of the second stress buffering material to create a second recess sidewall in the layer of second stress buffering material, the second recess sidewall being orthogonal to a major surface of the contact pad; and
removing some of the first stress buffering material to create a first recess sidewall in the layer of first stress buffering material, the first recess sidewall being orthogonal to the major surface of the contact pad;
wherein the first recess sidewall and the second recess sidewall are discontinuous.