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Aluminum oxide ͑Al 2 O 3 ͒ thin films have been prepared by the atomic layer deposition ͑ALD͒ using trimethylaluminum ͑TMA͒ and ozone ͑O 3 ͒ as precursors. The process pressure was varied from 200 mTorr to 1000 mTorr at 320°C, and its effect on the film properties was compared to that of the deposition temperature change from 320°C to 460°C. The film growth rate and film properties of thickness uniformity, impurity incorporation, and the step coverage in high aspect ratio features were characterized. It was found that the deposition temperature decrease led to film property deterioration and film growth rate increase. Increasing process pressure at lower temperature could not only help to retrieve the film properties, but also further increase the film growth rate. These improvements can be attributed to the change of surface saturation level, the enhancement of precursor diffusion condition, as well as the higher probability for surface reactions to occur at the active sites. The electrical and reliability performances on the dynamic random access memory capacitor confirmed the robustness of the high-pressure films. This study suggests that increasing process pressure may reduce the necessary cycle time/number to obtain the qualified film properties and the desired film thickness, which brings advantages of throughput for ALD semiconductor applications.Aluminum oxide ͑Al 2 O 3 ͒ is one of the most extensively studied materials due to its relatively high dielectric constant, high thermal stability, and good adhesion to many surfaces. 1,2 These properties make Al 2 O 3 attractive in the silicon microelectronics and thin-film device industry as a high-k material. Al 2 O 3 has been used as a capacitor dielectric material for dynamic random access memories ͑DRAMs͒ 1 and considered to replace SiO 2 as the gate dielectric material for metal oxide semiconductor field effect transistors ͑MOSFETs͒. 3,4 Among numerous deposition technologies in depositing Al 2 O 3 dielectric films, atomic layer deposition ͑ALD͒ has recently gained acceptance as a thin-film deposition technique in semiconductor device manufacturing due to its excellent film property performance. 5-8 The ALD process relies on a self-limiting film growth process based on sequential saturative surface reactions that are accomplished by pulsing the gaseous precursors on the substrate alternately and purging the reactor with inert gases between the reactant pulses. In this way, the self-limiting reaction are forced to be entirely on the surface, which can ensure excellent conformality along with large area uniformity and digital thickness control by selecting the number of deposition cycles repeated.Saturation behavior of an ALD reactant depends on many factors, such as dosage, purge time, purge gas flow rate, deposition temperature, etc. The effect of changing ALD process parameters on the resulting film properties has been studied. 9,10 It was known that ALD processes are thermally activated; lowering deposition temperature degrades film uniformity and conform...

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Employment of a tetragonal ZrO 2 film as the chargetrapping layer for nonvolatile memory was investigated and the NH 3 nitridation effect of the ZrO 2 film on memory performance was also explored in this letter. The permittivity of the tetragonal ZrO 2 film is slightly reduced from 38.7 to 36.9 after nitridation; nevertheless, nitridation introduces more trapping sites and passivates the grain boundary channel which results in a high operation speed in terms of 2.6-V flatband voltage shift by programming at +10 V for 10 ms and a good retention characteristic with 20.2% charge loss after ten-year operation at 125 • C, both are superior to that without NH 3 nitridation. Most importantly, the process is fully compatible with existent ULSI technology and paves the way to adopt a high-permittivity crystalline dielectric as the charge-trapping layer for future high-performance nonvolatile memory.

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