1. Field of the Invention
The present invention relates to a cylindrical capacitor and a method of fabricating the same. More particularly, the present invention relates to a high mechanical strength cylindrical capacitor and a method of fabricating the same.
2. Description of the Related Art
A semiconductor memory mainly comprises a transistor and a capacitor. As the process of fabricating the semiconductor memory needs to fabricate patterns with a high aspect ratio, the area available for accommodating the capacitor of each device is substantially reduced. However, as the memory space needed to operate a computer software program grows rapidly, the number of required capacitors also correspondingly increases. To satisfy this growing demand for capacitors, some basic modification is required to made to the existing techniques of manufacturing semiconductor device.
At present, the minimum capacitance of each capacitor unit in a dynamic random access memory (DRAM) is greater than 25 fF. With the reduction in design dimension, a number of methods for increasing the capacitance of each capacitor unit have been suggested. The two major methods include: 1) using high dielectric constant (high k) material to produce the capacitor dielectric layer; and, 2) increasing the surface area of the capacitor by forming a cylindrical structure, forming a rod structure, forming a wing structure or forming a complicated structure by performing multiple processes. The most common means of increasing the surface area of a capacitor unit is still the cylindrical structure. However, even for the cylindrical capacitor, the height of the capacitor cylinder has to be increased as the allowed dimension is reduced. Yet, raising the height of the capacitor cylinder will destabilize the entire capacitor cylinder so that the capacitor cylinder is easily toppled. As a result, there will be a substantial drop in the production yield of the capacitor.