Grating coupler and manufacturing method thereof

Abstract

The invention provides a grating coupler and a manufacturing method thereof. The manufacturing method comprises the following steps of: providing an SOI (Silicon On Insulator) substrate and etching top-layer silicon of the SOI substrate to form a coupling grating with the period of 500-800 nm; meanwhile, separating a CMOS (Complementary Metal-Oxide-Semiconductor Transistor) active region in the top-layer silicon; manufacturing a grating oxidizing layer covering the coupling grating and the CMOS active region on the coupling grating; forming a conductive layer on the surface of the grating oxidizing layer and etching the conductive layer to form a coating structure which has the same period as the coupling grating; meanwhile, forming a gate structure of a CMOS; and finally, forming a protection layer to finish the preparation. The preparations of the coupling grating, the grating oxidizing layer, the coating structure and the CMOS can be simultaneously finished and a mask can be shared, so that the manufacturing cost is reduced; the coupling efficiency is improved by an upper conductive coating covering the grating oxidizing layer; the coupling efficiency of the grating coupler is obviously improved by optimized structure parameters; and the dependency of the coupling efficiency on the thickness of an SOI buried oxide layer is greatly reduced by a novel grating coupler structure, so that the specification requirements on the SOI substrate are reduced.

Description

technical field [0001] The invention belongs to the field of semiconductors and optoelectronic integration, and in particular relates to a grating coupler and a manufacturing method thereof. Background technique [0002] Integrated silicon-based optical systems, due to their small device size and good compatibility with traditional integrated circuit CMOS processes, have become a hot research topic at present. Many micro-nano devices have been integrated on silicon, such as lasers, modulators, filters, couplers, buffers, etc. The grating is used to realize the function of the coupler, which has the advantages of small coupling area and high coupling efficiency, so it is widely used in planar optical systems. [0003] Si and SiO 2 The high refractive difference (about 2.0) provides the possibility to realize nano-optical waveguides and ultra-small-scale integrated optical waveguide devices, and has great application prospects in the fields of optical communication, optical ...

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Problems solved by technology

[0005] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a grating coupler and its manufacturing method, which are used to solve the problem that the coupling efficiency of the grating coupler in the prior art is difficult to improve, and the general grating coupler is not conducive to integration. Due to the CMOS process and strict requirements on the thickness of the buried oxide layer of SOI, the problem of high production cost

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