PEALD of Zirconium Oxide Using Tetrakis(ethylmethylamino)zirconium and Oxygen

Abstract

Highly uniform ZrO 2 films were deposited by plasma enhanced atomic layer deposition ͑PEALD͒ using tetrakis͑ethylmethylami-no͒zirconium ͑TEMAZ͒ and O 2 as precursors. The deposition rates were 0.14 and 0.11 nm/cycle at temperatures of 110 and 250°C, respectively. ZrO 2 films deposited at 150°C contained ϳ3% nitrogen, incorporated from the Zr-precursor, which contains four amino-groups. In the absence of a plasma, a ZrO 2 film was not deposited with TEMAZ and O 2 at 150°C. The electrical characteristics including breakdown strength and permitivity were also evaluated. The permitivities for 110°C-and 200°C-ZrO 2 films were 16.1 and 26.9, respectively. Dielectric materials with high permitivity ͑͒ as a substitute for SiO 2 have been extensively examined, as SiO 2 layers thinner than 1.5 nm cannot be used as a gate dielectric in sub-0.1 micrometer metal oxide semiconductor technology due to its high tunneling current which exceeds 1 A/cm 2 at 1 V. 1 The possibility of using highdielectrics, such as ZrO 2 and HfO 2 , etc., has recently been widely investigated due to dielectric constants that are much higher than that of SiO 2 and lower leakage currents far below that of an equivalent SiO 2 layer. The high-material as a gate dielectric or a capacitor is also an emerging issue in the fabrication of high current and high mobility thin film transistors for display applications.Among the available thin film deposition techniques, thin highdielectric films can be uniformly deposited using chemical vapor deposition ͑CVD͒ and atomic layer deposition ͑ALD͒ techniques. The ALD technique is based on the alternating exposure of a surface to two or more gas phase precursors and self-limiting surface reactions between the sequentially adsorbing precursors. Thus, ALD is known to be superior to CVD because of its extraordinarily good conformality and precise thickness control. Conventional ALD typically involves the use of metal chloride precursors such as HfCl 4 and ZrCl 4 , etc. and several oxygen precursors including H 2 O, ozone, and alkoxides for depositing oxide films in combination with the metal chlorides. It also requires a relatively high deposition temperature. 2-5 However, low-temperature deposition is becoming important in applications to flexible and light plastic electronic devices. For low-temperature applications, plasma-enhanced ALD ͑PEALD͒ is a promising deposition technique. 6-8 The use of an O 2 plasma in ALD enhances the deposition rate and electrical properties as well as film density compared to those of conventional ALD.In this paper, the deposition and characteristics of high-ZrO 2 films are reported for low-temperature applications including thin film transistor on a plastic substrate. The deposition of ZrO 2 films was carried out for the first time by PEALD using tetrakis͑ethylm-ethylamino͒zirconium ͓Zr͕N(C 2 H 5 )(CH 3 )͖ 4 , TEMAZ͔ as a Zrprecursor and an O 2 plasma as the oxidant. The effect of deposition temperature was first investigated on the material characteristics of ZrO 2 at temperatures rangin...

Room-temperature atomic layer deposition of ZrO2 using tetrakis(ethylmethylamino)zirconium and plasma-excited humidified argon

“…In the present ALD experiment, we obtained a higher growth rate (0.17 nm/cycles) compared with that in the conventional plasma ALD, for which a ZrO 2 growth per cycle of 0.14 nm/cycle was reported by Yun et al [15]. We assumed that present ZrO 2 is not so dense compared with the ZrO 2 film made with the conventional ALD process, because the present film is amorphous due to its low growth temperature.…”

“…For ZrO 2 , Yun et al [15] To decrease the deposition temperature, the plasma-excited water vapor and Ar (humidified Ar) is used in this work. Previously we reported RT-ALD of SiO 2 with tris(dimethylamino)silane (TDMAS) and the same oxidizing agent with remote plasma system.…”

Atmospheric Pressure Plasma Enhanced Spatial ALD of ZrO2for Low-Temperature, Large-Area Applications

“…The resistivity of the layers was calculated from the measured current at a bias of 4 V and the average over 6 capacitors is summarized in Table II. As previously reported, 8,9,28 the resistivity decreases slightly with increasing deposition temperature and is of the order of 10 11 m for all layers, in agreement with literature value. 51,52 The corresponding leakage current density is less than 5 × 10 −8 A/cm 2 .…”

“…Upon increasing the temperature, the refractive index for the thermal ALD process approaches the literature value of 2.19; 45 however, the GPC is still very low compared to the plasma process, as already reported for vacuum depositions. 8 Table I shows that at 150…”

The Atomic Layer Deposition of HfO2 and ZrO2 using Advanced Metallocene Precursors and H2O as the Oxygen Source

“…Although some precursors offer such conditions to varying extents, improvement in one or more of these areas for the growth of HfO 2 and ZrO 2 would be a notable advance. To date, a variety of ligand types have been used for the ALD of HfO 2 and ZrO 2 , including some traditional examples such as halides, [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] alkylamides, [20][21][22][23][24][25][26][27][28] and alkoxides, [29][30][31][32][33][34][35][36][37][38][39][40] as well as others. [41][42][43] Recent studies, however, have demonstrated the ALD growth of these materials using hafnocene-and zirconocene-based precursors, and the potential viability of the resulting films in device applications.…”