gan epitaxial structure based on si substrate and its preparation method

Abstract

The invention belongs to the field of semiconductor technology, and in particular discloses a GaN epitaxial structure based on a Si substrate, which includes a first AlN buffer layer, a layered slip layer, and a second AlN buffer layer sequentially stacked on a Si substrate 、Al x Ga 1‑x N buffer layer and GaN epitaxial layer; Al x Ga 1‑x The value range of the content x of Al in the N buffer layer is 0<x<1. The invention also discloses a preparation method of the GaN epitaxial structure. According to the GaN epitaxial structure of the present invention, a layered slip layer is prepared between the Si substrate and the GaN epitaxial layer, and the internal layered structure of the layered slip layer is utilized. Slip occurs between them, so that the tensile stress borne by the subsequent GaN epitaxial layer is greatly reduced, and the generation of cracks on the surface of the GaN epitaxial layer is suppressed.

Description

technical field [0001] The invention belongs to the technical field of semiconductors, and in particular relates to a GaN epitaxial structure based on a Si substrate and a preparation method thereof. Background technique [0002] Sapphire, Si and SiC are the mainstream substrates currently used for the epitaxy of gallium nitride-based devices; among them, the preparation technology of Si substrate is the most mature, which can be prepared into large-sized, high-quality wafers at low prices. From the device point of view, the Si substrate is beneficial to the heat dissipation of the device, so the high electron mobility transistor (HEMT) device on the Si substrate is the focus and focus of GaN power device research. [0003] The key to epitaxial high-quality GaN on Si substrates is to solve the problem of tensile stress. The source of tensile stress is the difference in lattice constant and thermal expansion coefficient between Si and GaN. If epitaxial directly on the Si su...

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Problems solved by technology

against Al x Ga 1-x N buffer layer technology, its epitaxial Al x Ga 1-x The process of the N buffer layer makes the tray also covered with a thick layer of Al x Ga 1-x N material, Al with high Al composition x Ga 1-x The N material is not easy to remove, and the covered Al x Ga 1-x The N material will affect the temperature uniformity of the tray, resulting in the drift of the process conditions; and in order to completely remove the Al x Ga 1-x N material, the tray needs to be put into the furnace for cleaning, which increases the maintenance cost and time of the tray

For the insertion layer stress clipping method, the commonly used insertion layers include AlN / GaN superlattice, SiN insertion layer and low-temperature AlN insertion layer, but the AlN / GaN superlattice insertion layer has high requirements for equipment, and the epitaxy process is complicated. In the process, the valve needs to be switched frequently, which will damage the equipment; while the SiN insertion layer and the low-temperature AlN insertion layer have high requirements on the epitaxial process, too thick an insertion layer will reduce the crystal quality of the upper layer GaN, and too thin can not prevent the propagation of tensile stress

For the selected area epitaxy method, it needs to add an epitaxy process and lithography, etching and other processes; at the same time, in the process of lithography and other processes, it is inevitable to contaminate the surface, resulting in leakage channels inside the material after the second epitaxy. will degrade the performance of HEMT devices

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