Etching method of polycrystalline silicon on quartz substrate and manufacture method of planar optical waveguide

Abstract

The invention discloses an etching method of polycrystalline silicon on a quartz substrate and a manufacture method of planar optical waveguide. The etching method comprises the steps: a photoresist mask layer is formed on the surface of a polycrystalline silicon layer; C4F8 and SF6 are used for dry etching of the polycrystalline silicon layer, and grooves with a set depth and a set height are formed, wherein the flow quantity of the C4F8 is 1.5-2.5 times that of the SF6, and the flow quantity of the SF6 is 40 sccm-50 sccm. With adopting of the etching method, excessive side face etching caused because a passive film is too thin can be prevented, and insufficient side face etching caused because the passive film is too thick can be prevented, so as to ensure the etched groove side surface has better verticality and better smoothness.

Description

technical field [0001] The invention relates to the technical field of semiconductor device manufacturing technology, and more specifically, relates to a method for etching polysilicon on a quartz substrate and a method for manufacturing a planar optical waveguide. Background technique [0002] When making a planar optical waveguide, it is necessary to form a groove with a set depth and width ratio on the surface of the silicon dioxide layer on the quartz substrate to form an optical path. When making a planar optical waveguide (such as an optical splitter), it is necessary to form a polysilicon layer on the surface of the silicon dioxide layer, then etch the polysilicon layer to form a groove of a set size, and then use the etched polysilicon layer as a mask The silicon dioxide layer is etched to form trenches of defined dimensions. [0003] Existing etching methods for polysilicon are all based on the design of silicon substrates. If they are directly used in the manufact...

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Problems solved by technology

[0003] The existing polysilicon etching methods are all based on the design of the silicon substrate. If they are used directly in the production of planar optical waveguides, the verticality and smoothness of the side walls of the trenches on the polysilicon surface will be poor.

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