Semiconductor device with reduced interconnect capacitance
View Patent ↗A semiconductor device has interconnecting lines disposed side by side in a dielectric film. Mutually adjacent pairs of interconnecting lines are separated by a substantially constant distance from top to bottom, but the width of each interconnecting line varies from top to bottom. For example, the interconnecting lines may have T-shaped or trapezoidal cross sections, interconnecting lines having wide tops alternating with interconnecting lines having wide bottoms. These cross-sectional shapes can be formed by simple fabrication processes. Since the facing sides of mutually adjacent interconnecting lines do not form mutually parallel vertical planes and therefore do not function as parallel plate electrodes, the interconnect capacitance is reduced.
1. A semiconductor device, comprising:
a lower dielectric film;
an upper dielectric film formed in contact with the lower dielectric film;
a first interconnecting line having a first lower part formed in the lower dielectric film and a first upper part formed in the upper dielectric film, the first upper part making contact with the first lower part;
a second interconnecting line having a second lower part formed in the lower dielectric film and a second upper part formed in the upper dielectric film, the second upper part making contact with the second lower part;
wherein the first lower part and the second upper part have a first constant width;
the second lower part and the first upper part have a second constant width greater than the first constant width; and
the first interconnecting line and the second interconnecting line have a first height and the first upper part, the second upper part, the first lower part, and the second lower part have a second height equal to half the first height.
2. The semiconductor device of claim 1 , wherein the first interconnecting line and the second interconnecting line are mutually adjacent.
3. The semiconductor device of claim 1 , wherein the first upper part, the second upper part, the first lower part, and the second lower part are rectangular.
4. The semiconductor device of claim 3 , wherein the first interconnecting line and the second interconnecting line have a cross-sectional T shape.
5. A semiconductor device, comprising:
a lower dielectric film;
an upper dielectric film formed in contact with the lower dielectric film;
a first interconnecting line having a T-shape formed by a first vertical leg formed only in the lower dielectric film and a first horizontal leg formed only in the upper dielectric film, the first horizontal leg making contact with the first vertical leg;
a second interconnecting line having an inverted T-shape formed by a second horizontal leg formed only in the lower dielectric film and a second vertical leg formed only in the upper dielectric film, the second vertical leg making contact with the second horizontal leg;
wherein the first vertical leg and the second vertical leg have a same width, which is constant over an entire length of the respective vertical legs;
the second horizontal leg and the first horizontal leg have a same width, which is constant along the respective horizontal legs, the width of the horizontal legs being greater than the width of the vertical legs; and
the first interconnecting line and the second interconnecting line have a first height, and the first vertical leg, the second vertical leg, the first horizontal leg, and the second horizontal leg each have a second height equal to half the first height, the heights being measured in a vertical direction, the widths being measured in a horizontal direction.