Trench manufacturing method

Abstract

The invention discloses a trench manufacturing method, which comprises the following steps of: depositing a silicon nitride layer on a doped silicon substrate, depositing an oxide layer, and etching the oxide layer, the silicon nitride layer and the doped silicon substrate in turn by adopting a photoetching process and an etching process so as to form an upper half part of a trench; depositing a nonmetallic silicon nitride layer on the upper half part of the trench and the surface of the oxide layer; taking the patterned oxide layer as a mask, etching the nonmetallic silicon nitride layer at the bottom of the upper half part of the trench, and continuously etching the doped silicon substrate to obtain a trench, and forming a side wall of the nonmetallic silicon nitride layer on the upper half part of the trench; taking the side wall of the nonmetallic silicon nitride layer on the upper half part of the trench as a mask, etching the trench by adopting a wet method, and widening the lower half part of the trench so as to form a trench; and removing the nonmetallic silicon nitride layer. In the method, the trench of an access unit of a storage is manufactured on the basis of not polluting a semiconductor device, the manufacturing process is simple, and the characteristics of the manufactured trench can be improved.

Description

technical field [0001] The invention relates to a manufacturing technology of a semiconductor device, in particular to a method for manufacturing a trench. Background technique [0002] With the development of the manufacturing process of semiconductor devices, the feature size (CD) of semiconductor devices is getting smaller and smaller, and the requirements for the manufacturing process are also getting higher and higher. For memory, such as dynamic random access memory (DRAM), as the feature size decreases, how to accurately fabricate the structure of the access unit, so that the capacitance value of the access unit of the DRAM with the feature size of 100 nanometers and below It is around 30 femtofarads (fF) and has become a key to the production process. [0003] The access unit of DRAM adopts stacked structure or trench structure usually, because the present invention only relates to the structure improvement of the access unit in the DRAM of trench structure, so here...

AI Technical Summary

Problems solved by technology

[0017] Although the trench of the DRAM access unit can be made by adopting the above-mentioned process, when the wet etching barrier layer 50 is made in step 202, due to the existence of metal ions in the chemical reaction process, the semiconductor device will be polluted, and it is necessary to wet etch the barrier layer 50. The etch stop layer 50 is accurately deposited on the surface of the silicon nitride layer 20 and the upper half of the channel 40, but cannot be deposited on the lower half of the channel 40, so a special reaction chamber and precise process are required, which is difficult to control

Therefore, the groove characteristics of the manufactured DRAM access structure are not high, resulting in poor access performance of the final DRAM access unit.

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