Deposition method capable of enhancing preferred orientation growth of AlN film

Abstract

The invention relates to a deposition method capable of enhancing the preferred orientation growth of an AlN film. The deposition method comprises the following steps: adopting an ion beam-assisted deposition technique to prepare an AlN homogeneous transition layer: when using an Ar + ion beam of 2.0-2.5keV / 20-50mA for depositing an Al film in a sputtering way on a substrate, using a moderate-energy N+ ion beam of 20-35keV / 2-8mA for bombarding the Al film in an assisting way; and then depositing the AlN film by adopting magnetron sputtering, wherein base pressure is less than or equal to 5x10<-4>Pa, working air pressure is 0.5-10Pa and substrate temperature is 200 DEG C-500 DEG C. Through pre-depositing the homogeneous transition layer, the invention has the advantages that the internal stress between the film and the substrate can be effectively reduced, the full (002) orientation AlN film is formed, the surface roughness of the film is reduced, the bonding strength between the film and the substrate is increased and the film product can satisfy the requirements on the application in surface acoustic wave devices, acoustic bulk wave devices and other microelectronic devices and power devices.

Description

technical field [0001] The invention relates to an AlN thin film preparation process, and further refers to a deposition method for enhancing the preferred orientation growth of the AlN thin film. Background technique [0002] AlN (aluminum nitride) film has many excellent properties such as band gap, high thermal conductivity, high resistivity, high breakdown electric field strength, small dielectric coefficient, good chemical stability and strong corrosion resistance, and has a wide range of applications. , where AlN film is an ideal piezoelectric material due to its high acoustic wave propagation velocity and large piezoelectric coupling coefficient, especially suitable for making surface acoustic wave (SAW) devices and bulk wave (BAW) devices in the GHz band. Since the surface acoustic wave velocity of the c-axis (002) orientation of the AlN film is 11354m / s, which is greater than the surface acoustic wave velocity of the a-axis orientation (100) 5500m / s, and the piezoel...

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Problems solved by technology

Domestic Wang Lianwei et al. used pulsed laser deposition of ZnO as a transition layer, and then deposited AlN film, which can significantly improve the preferred orientation degree of the (002) crystal plane of the film and reduce the surface roughness of the film, but the bonding strength of the film is not ideal (ZL 99125749.9 )

Although these transition layers can reduce the internal stress to a certain extent and improve the quality of the film, due to the use of heterogeneous transition layers, the AlN film is heteroepitaxially grown, and there are still internal stress, lattice mismatch and mutual interaction between the transition layer and the AlN film. Diffusion etc.

Among these heterogeneous transition layers, the preparation process of transition layers such as 3C-SiC and TiN is different from that of AlN thin films, and the cost is high. If they are deposited in the same vacuum chamber, elements such as Si and Ti may contaminate AlN thin films.

ZnO and Al 2 o 3 Although the oxide transition layer can significantly improve the preferred orientation of the AlN film, the presence of oxygen should be avoided when depositing the AlN film. Therefore, it is difficult to deposit the oxide transition layer and the AlN film in the same vacuum chamber. The process becomes complicated and the cost of the process increases; there are also studies using a homogeneous transition layer, such as Liu Chang et al., who used AlN buffer layers and AlN thin films to grow alternately to prepare high-quality thin films with smooth surfaces, but the substrate temperature was higher than 500 ° C ~ 780°C, and the process is more complicated (ZL200810048681.3)

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