Influences Study on MIM capacitors' reliability

Reliability assessment tests are used to evaluate the quality of different process schemes of MIM capacitors. Typically, VRAMP tests can be used to check for extrinsics; which are common and popular method used for evaluating yield issues and early life failures (in which the product failures in ppm level); while TDDB tests are used to determine the intrinsic quality of the capacitor dielectrics; thus the lifetime will be extrapolated accordingly from its dependency from accelerated tests at different higher stress conditions down to the corresponding use condition. In this paper, we will summarize the different approaches of making high capacitance density MIM capacitors in two dimensions - thickness or area: that is to say to achieve with thinner dielectrics or by using stack layers (i.e. single, double, or even triple stacked up in parallel). Comparisons are made in terms of breakdown voltages, leakages, linearity, RF Q-factors and mainly the reliability impact: extrinsics level and intrinsic lifetime even with the same capacitance density. Further Study on various process variants with reliability assessment has also been done, and will be discussed here as well.