Conference Paper

HfO2 and lanthanide-doped HfO2 MIM capacitors for RF/mixed IC applications

Dept. of Electr. & Comput. Eng., Nat. Univ. of Singapore, Singapore
Conference: VLSI Technology, 2003. Digest of Technical Papers. 2003 Symposium on
Source: IEEE Xplore


We demonstrate high quality HfO2-metal-insulator-metal (MIM) capacitors with a high capacitance of 4.7 fF/cm2 and a leakage current density of less than 10-8 A/cm2, meeting ITRS requirement for analog precision capacitor applications. In addition, we demonstrate that doping HfO2 with Lanthanide (Tb) at an optimum concentration improves both voltage linearity and leakage current density of HfO2 MIM capacitor, allowing further reduction of insulator thickness and achieving a capacitance density of 13.3 fF/μm2 with leakage current meeting requirements for RF bypass capacitors applications. These values are superior to that reported in the literature, suggesting the potential use of these dielectrics for future RF/mixed signal IC applications.

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    • "shows the dependence of α as a function of CET or the inverse capacitance density (1/C). An exponential decrease of α with increasing CET or 1/C was observed for the Ta 2 O 5 [12], HfO 2 [10], Tb-doped HfO 2 [8], TiTaO [18], and STO MIM capacitors. This is due to the trap-related leakage current Fig. 9 "
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    ABSTRACT: For the first time, we successfully fabricated and demonstrated high performance metal-insulator-metal (MIM) capacitors with HfO/sub 2/-Al/sub 2/O/sub 3/ laminate dielectric using atomic layer deposition (ALD) technique. Our data indicates that the laminate MIM capacitor can provide high capacitance density of 12.8 fF//spl mu/m/sup 2/ from 10 kHz up to 20 GHz, very low leakage current of 3.2 /spl times/ 10/sup -8/ A/cm/sup 2/ at 3.3 V, small linear voltage coefficient of capacitance of 240 ppm/V together with quadratic one of 1830 ppm/V/sup 2/, temperature coefficient of capacitance of 182 ppm//spl deg/C, and high breakdown field of /spl sim/6 MV/cm as well as promising reliability. As a result, the HfO/sub 2/-Al/sub 2/O/sub 3/ laminate is a very promising candidate for next generation MIM capacitor for radio frequency and mixed signal integrated circuit applications.
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    ABSTRACT: High-k MIM capacitors like HfO<sub>2</sub> are of great interest for Si analog and RF applications recently. This work is intended to explain the dependences of VCC on dielectric thickness and frequency as well as the temperature dependence of capacitance of HfO<sub>2</sub> MIM capacitors. Based on a free carrier injection model, a unified understanding is achieved for the first time: (1) the thickness (t) dependence of VCC (α), which exhibits a relation of α∝t<sup>-n</sup>, is an intrinsic property due to E-field polarization; (2) the frequency dependence of VCC, the stress induced VCC, and temperature dependences of capacitance are all due to change of relaxation time with different carrier mobility in the insulator. This model is also applied to predict the VCC for future applications.
    No preview · Conference Paper · Jan 2004
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