Method for Simultaneously Filling and Planarizing Deep Trenches of Different Sizes

Abstract

The invention discloses a method for simultaneously filling and flattening deep trenches with different sizes, which comprises the following steps: (1)depositing a layer or a plurality layers of combination bodies of oxide film or nitride film on a silicon substrate as a barrier layer, (2)depositing light-sensitive lacquer, after development, etching the combination bodies of oxide film or nitride film and revealing a silicon base which needs to etch the deep trenches in follow-up processes,(3) removing the light-sensitive lacquer and producing images of the deep trenches with different depth-to-width ratios through etching with utilization of the combination bodies of oxide film or nitride film as a barrier layer, (4)depositing a layer of oxidation film which is good in steps covering power on a silicon slice, (5)removing the oxidation film above the barrier layer through the manner of chemical mechanical polish, and therefore, depth-to-width ratios of the deep trenches are reduced, (6) filling all the deep trenches with different sizes with a plurality of continuous rounds of oxide film deposition and chemical mechanical polish. Filling difficulty of the deep trenches which have large height-to-width ratios is reduced and at the same time fillers in the large opening deep trenches are not removed. Process is simple and effect is obvious.

Description

technical field [0001] The invention relates to a semiconductor process method in a semiconductor integrated circuit. Background technique [0002] In today's semiconductor applications, more and more devices that need to use deep trench structures to realize functions have appeared. For some special devices, such as optical splitters, there will be some openings with different opening sizes on the silicon wafer. A deep trench with an opening size from 0.8 microns to 100 microns and a depth from 2 microns to 10 microns. The aspect ratio varies widely, from 0.02 to 12.5. The deep trenches of different sizes in this type of device not only need to be filled completely without leaving any voids, but also because the filling film is thicker than the traditional process, ranging from 2 microns to 5 microns, chemical mechanical polishing will be used to ensure the opening In-plane filling uniformity of deep trenches with unequal orifice sizes. Therefore, there will be great cha...

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Problems solved by technology

[0003] The traditional method is to fill the trench with chemical vapor deposition (CVD). If the aspect ratio is large, etchback will be used to enlarge the opening at the top of the trench, and then continue to fill. However, for large openings Deep trenches cause the bottom to be etched at the same time, thus preventing filling of large open trenches

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