Redistribution layer with microstrips
View Patent ↗A semiconductor device includes a completed semiconductor chip and a dielectric layer overlying the completed semiconductor chip. A redistribution layer overlies the completed semiconductor chip and is embedded in the dielectric layer. The redistribution layer includes a plurality of microstrip conductors. Each microstrip conductor has a height and a width selected such that the height is at least twice the width. In addition, each microstrip conductor is separated from an adjacent microstrip conductor by a spacing distance that is at least twice the width.
1. A method of making a semiconductor device, the method comprising:
fabricating a semiconductor integrated circuit that includes an uppermost metallization level;
forming a dielectric layer over the semiconductor integrated circuit and over the uppermost metallization;
forming a plurality of trenches in the dielectric layer, each of the trenches having a width and a depth that is greater than the width, a bottom surface of the trench being electrically isolated from the uppermost metallization; and
filling the trenches with a conductor, the conductor serving as a redistribution layer that reroutes contact areas in the uppermost metallization.
2. The method of claim 1 , wherein filling the trenches comprises:
depositing a seed layer within the trenches; and
electrodepositing the conductor over the seed layer.
3. The method of claim 2 , wherein depositing a seed layer within the trenches further deposits a seed layer over an upper surface of the dielectric layer outside the trenches, the method further comprising forming a masking layer over the upper surface of the dielectric layer to prevent the conductor from being electrodeposited on the upper surface.
4. The method of claim 2 , wherein the conductor comprises copper.
5. The method of claim 1 , wherein forming a plurality of trenches comprises forming substantially rectangular shaped trenches, wherein the ratio of the depth to the width of each trench is at least 4:1.
6. The method of claim 1 , wherein forming a plurality of trenches comprises forming trenches that have sloping sidewalls.
7. The method of claim 6 , wherein forming a plurality of trenches comprises forming a plurality of v-shaped trenches.
8. The method of claim 1 , wherein forming a dielectric layer comprises forming a polymer layer.
9. The method of claim 8 , wherein forming a dielectric layer comprises forming a photoresist layer.
10. The method of claim 1 , wherein the ratio of the depth of the trench to the width of the trench is between about 2:1 and 10:1 and wherein each trench is separated from a closest adjacent trench by at least a minimum spacing distance, wherein the ratio of the minimum spacing distance to the width of the trench is at least 5:1.