Dual layer dielectric stack for microelectronics having thick metal lines
Embodiments of the invention include apparatuses and methods relating to dual layer dielectric stacks for thick metal lines of microelectronic devices. In one embodiment, the dual layer dielectric stack includes a first dielectric layer that is planar and mechanically strong and the second dielectric layer can be patterned by photolithography to the required critical dimensions.
1. A method comprising:
forming a thick metal line on a surface of a substrate, wherein the substrate includes a device region and a metallization region and wherein the thick metal line is electrically connected to the metallization region;
forming a substantially planar first dielectric layer over the substrate surface and the thick metal line, wherein forming the substantially planar first dielectric layer comprises a cure step, and wherein the first dielectric layer shrinks by less than about 10% by volume during the cure step;
forming a second dielectric layer over the first dielectric layer;
patterning the second dielectric layer to form an opening in the second dielectric layer to expose a region of the first dielectric layer;
etching at least a portion of the first dielectric layer within the opening to expose a portion of the thick metal line; and
forming a conductive via that contacts the thick metal line.
2. The method of claim 1 , wherein the thick metal line has a thickness equal to or greater than about 5 microns.
3. The method of claim 1 , wherein the opening has a critical dimension of less than or equal to about 10 microns.
4. The method of claim 1 , wherein the first dielectric layer comprises bisbenzocyclobutene (BCB).
5. The method of claim 1 , wherein a ratio of a first height of the substantially planar first dielectric layer over the substrate over a second distance of the substantially planar first dielectric layer over the thick metal line is greater than about 0.8.
6. The method of claim 1 , wherein the second dielectric layer comprises a polyimide.
7. The method of claim 1 , wherein etching the first dielectric layer comprises an oxygen plasma etch.
8. The method of claim 1 , further comprising:
forming a nitride passivation layer over the thick metal line and the substrate surface before forming the first dielectric layer over the substrate surface.
9. The method of claim 1 , further comprising:
forming a bump over the conductive via.
10. A method comprising:
forming a thick metal line on a surface of a substrate, wherein the substrate includes a device region and a metallization region and wherein the thick metal line is electrically connected to the metallization region;
forming a substantially planar first dielectric layer including bisbenzocyclobutene (BCB) over the substrate surface and the thick metal line;
forming a second dielectric layer including polyimide over the first dielectric layer;
patterning the second dielectric layer to form an opening in the second dielectric layer to expose a region of the first dielectric layer;
etching at least a portion of the first dielectric layer within the opening to expose a portion of the thick metal line; and
forming a conductive via that contacts the thick metal line,
wherein:
a ratio of a first height of the substantially planar first dielectric layer over the substrate over a second distance of the substantially planar first dielectric layer over the thick metal line is greater than about 0.8.
11. The method of claim 10 , wherein the thick metal line has a thickness equal to or greater than about 5 microns.
12. The method of claim 10 , wherein the opening has a critical dimension of less than or equal to about 10 microns.
13. The method of claim 10 , further comprising:
forming a bump over the conductive via.