Preparation method of three-dimensional memory and etching method of groove bottom

Abstract

A method for preparing a three-dimensional memory, comprising: stacking layers; forming storage strings; forming grooves; removing the first insulating layer in the stacking layers; Barrier layer; fill the vacancies with conductive material to form a conductive layer; form a spacer layer conformally in the trench; perform a first etch process to remove the barrier and spacer layers at the bottom of the trench; perform a second etch process , so that the etch rate of the barrier layer and the spacer layer are the same. The preparation method of the three-dimensional memory provided by the present invention has the second etching process and the etching rate of the barrier layer and the silicon oxide layer are the same in the second etching process, so it can better suppress the formation of the step at the opening of the trench. Generated, and then can obtain a common source contact with good performance.

Description

technical field [0001] The invention mainly relates to the field of memory technology, in particular to a method for preparing a three-dimensional memory and a method for etching the bottom of a trench. Background technique [0002] With the continued emphasis on highly integrated electronic devices, there is a continuing need for semiconductor memory devices that operate at higher speeds and lower power and have increased device densities. To this end, devices with smaller dimensions and multilayer devices with transistor cells arranged in horizontal and vertical arrays have been developed. 3D NAND is an emerging type of flash memory developed by the industry. It solves the limitations of 2D or planar NAND flash memory by vertically stacking multi-layer data storage units. It has excellent precision and supports higher capacity in a smaller space. The storage capacity can create a storage device with a storage capacity several times higher than that of similar NAND technol...

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Problems solved by technology

However, due to the difference in etching rate, after the above etching process is completed, a raised structure similar to a step (hereinafter referred to as a step) is easily formed at the opening of the trench, which will affect the filling effect of the subsequent tungsten wall.

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