The MIM capacitors with HiO_2 and HfAlO_x are investigated for Si RF and analog applications. The results show that both the capacitance density and voltage coefficients of capacitance (VCCs) increase with decreasing the HfO_2 thickness. A high capacitance density of 13 fF/μm~2 with a low leakage current and a VCC of 607 ppm/V is obtained for 10 nm HfAlO_2 MIM capacitor, which can meet the requirement of the ITRS roadmap by 2007 for silicon RF application. On the other hand, it was found that both the capacitance density and voltage coefficients of capacitance (VCC) values of the HfAlO, MIM capacitors decrease with increasing Al_2O_3 concentration. The results show that HfAlO_x MIM capacitor with an Al_2O_3 mole fraction of 0.14 is optimized. It provides a high capacitance density of 3.5 fF/μm~2 and a low VCC of ～140 ppm/V~2. Also, small frequency dependence, low leakage current, and low loss tangent are obtained. Thus, the HfAlO_x, MIM capacitor with an Al_2O_3 mole ratio of 0.14 is very suitable for use in silicon analog applications.
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