High density metal-insulator-metal capacitor based on ZrO2∕Al2O3∕ZrO2 laminate dielectric

Abstract

The metal-insulator-metal (MIM) capacitor for analog and rf applications has been developed with ZrO2∕Al2O3∕ZrO2 laminate as the dielectric. The high capacitance density of 21.54fF∕μm2 can be achieved due to the tetragonal ZrO2 which makes the higher dielectric constant of 38.7. This MIM capacitor also demonstrates the quadratic voltage coefficient of 2443ppm∕V2 and the good leakage current of 2.11×10−6A∕cm2 at 2V which is ascribed to the inserted Al2O3. Since the Schottky emission is suggested as the major dielectric conduction mechanism, a further reduced quadratic voltage coefficient and leakage characteristic can be realized by using a high work-function electrode. The combination of the promising electrical properties and the desirable process integration renders this structure highly suitable for advanced MIM capacitors.

Toward Low-Power Flash Memory: Prospect of Adopting Crystalline Oxide as Charge Trapping Layer

“…Note that tetragonal and cubic ZrO2 can be stabilized above 1127 • C and 2297 • C, respectively. Besides stabilizing at the high temperature, these desirable phases can also be obtained at a lower temperature by reducing the crystallite size [15][16] or incorporating impurities such as N, Ge, Sn, Ce, Ti, and Si [17] into the lattice followed by a thermal annealing. Thanks to the unique dielectric properties of crystalline ZrO2, it presents the great perspectiveness as the CTL for flash memory devices and it is the major reason of reviewing the promising material.…”

Nitrided Tetragonal $\hbox{ZrO}_{2}$ as the Charge-Trapping Layer for Nonvolatile Memory Application

“…Then, the chargetrapping layer and the blocking dielectric were, respectively, formed by ZrO 2 of 12 nm and Al 2 O 3 of 21 nm, both by atomic layer deposition (ALD) at 350 • C. The ZrO 2 film was deposited by Zr[N(CH 3 )C 2 H 5 ] 4 (TEMAZ)-ozone (O 3 ) with tetragonal phase while the Al 2 O 3 film was of amorphous phase formed by Al(CH 3 ) 3 (TMA)-ozone (O 3 ) [10]. Since a nonvolatile memory device with HfON as the charge-trapping layer has exhibited excellent performance due to a smaller conduction band offset respective to Si substrate along with the higher trap density and/or deeper trap energy as compared with HfO 2 [4], [5], NH 3 plasma nitridation of the tetragonal ZrO 2 film was performed at 480 • C for 200 s on some samples to investigate the impact of nitrogen incorporation on memory performance.…”

“…Finally, postdeposition annealing was performed on all samples at 950 • C for 30 s followed by aluminum deposition as the electrode. Note that to eliminate the possible nitridation effect on the tunnel dielectric that would introduce noise in the permittivity extraction of the nitrided ZrO 2 , MIM capacitors [10] with only the nitrided tetragonal ZrO 2 as the insulator were also fabricated to focus on the nitridation effect on the dielectric properties. High-resolution cross-sectional transmission electron microscopy was used to characterize the thickness of each layer while X-ray diffraction (XRD) was employed to confirm the crystalline structure of the ZrO 2 film.…”

“…Recently, crystalline ZrO 2 has drawn intensive attention because of the higher permittivity as compared to its amorphous phase. Among the crystalline phases of ZrO 2 , tetragonal phase enjoys the highest permittivity which is theoretically predicted to be 46.6 [7] and finds its applications to high-k gate dielectrics [8], [9] and high-density metal-insulator-metal (MIM) capacitors [10]. In this letter, a tetragonal ZrO 2 film was introduced as the charge-trapping layer for nonvolatile memory and the impact of NH 3 nitridation of the tetragonal ZrO 2 film on memory performance was also explored.…”

Abnormally enhanced dielectric constant in ZrO2/Ta2O5 multi-laminate structures by metallic Ta formation

“…In particular, the high dielectric constant ($ 40) of tetragonal ZrO 2 crystals and the relatively wide band gap (5.7 eV) of this material have attracted much interest [6,7]. While the dielectric constant of hexagonal Ta 2 O 5 ($ 50) is even higher, its lower band gad energy (4.5 eV) means that leakage currents are more intense in Ta 2 O 5 than in ZrO 2 [8].…”