Semiconductor devices are used in many electronic and other applications. Semiconductor devices comprise integrated circuits that are formed on semiconductor wafers by depositing many types of thin films of material over the semiconductor wafers, and patterning the thin films of material to form the integrated circuits.
There is a trend in the semiconductor industry towards reducing the size of features and/or improving performance of the semiconductor devices. For example, features of devices are scaled to improve on current performance, performance of parasitic resistances are decreased etc. However, such technological progress requires overcoming many challenges. One challenge involves the contact formation in the front-end-of-line that includes silicidation of active area and forming contacts to it through an insulating layer. Scaling challenges these processes by decreasing the contact sizes as well as the contact to contact spacing. Increasingly silicidation introduces defects that significantly reduce process yields. Another challenge is the improvement in the performance of diodes used in semiconductor devices.
Schottky diodes, which are metal-semiconductor diodes, are conventionally formed by contacting silicide regions with semiconductor regions. This is because of the compatibility of silicide based diodes with conventional semiconductor processing. However, such diodes have a number of limitations. For example, they are susceptible to increased leakage currents at corners, for example, due to thinner silicidation as well as due to the existence of increased field regions.
FIG. 1, which includes FIGS. 1a and 1b, illustrates a conventional silicide based Schottky diode, wherein FIG. 1a illustrates a top view and FIG. 1b illustrates a cross-sectional view of the semiconductor device.
Referring to FIG. 1b, a Schottky contact is made between a silicide contact region 23 and a first doped region 20. The silicide contact region 23 is formed on the first doped region 20 and is formed between adjacent isolation regions 50. The contact to the semiconductor is made through silicide regions 22 formed over the second doped region 21, which is a heavily doped region for contacting the semiconductor portion of the diode.
The isolation regions 50 prevent the silicide contact region 23 from directly contacting the silicide regions 22. In some devices, the silicide contact region 23 is formed under the contact plugs 31, for example, in trenches under the contact plugs 31, so that a plurality of silicide contact regions 23 are formed under the contact plugs 31.