Three-dimensional memory and its manufacturing method

Abstract

The invention discloses a three-dimensional memory and a manufacturing method thereof, including forming a hard mask layer on a substrate and patterning it; using the hard mask pattern to form a semiconductor boss on the substrate; forming a doping region on the top of the semiconductor boss ; forming a dielectric layer stack on the hard mask pattern and the semiconductor protrusion; etching the dielectric layer stack to form a vertical channel hole exposing the semiconductor protrusion. According to the three-dimensional memory manufacturing method of the present invention, the channel hole in the dielectric layer stack is formed after the doped boss is first formed on the substrate by using the hard mask pattern, and the film-forming quality, height and height of the boss at the bottom of the channel hole are improved. The uniformity of doping concentration reduces the growth defects of the vertical channel region and improves the reliability of the device.

Description

technical field [0001] The invention relates to a three-dimensional memory and a manufacturing method thereof, in particular to a three-dimensional NAND memory unit transistor and a manufacturing method thereof. Background technique [0002] In order to improve the density of memory devices, the industry has made extensive efforts to develop methods of reducing the size of two-dimensionally arranged memory cells. As the size of memory cells in two-dimensional (2D) memory devices continues to shrink, signal collisions and interference can increase significantly, making it difficult to perform multi-level cell (MLC) operations. In order to overcome the limitations of 2D memory devices, the industry has developed memory devices with a three-dimensional (3D) structure to increase integration density by three-dimensionally arranging memory cells on a substrate. [0003] A typical 3D NAND manufacturing process such as Figure 1a As shown, a stacked structure 2 (for example, a str...

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Problems solved by technology

[0005] However, in the actual manufacturing process, since the aspect ratio of the channel hole 2H is too large (for example, greater than or equal to 10, 20), it is very difficult to remove the defects at the bottom, and the film formation quality of the epitaxial growth boss 1E is not good, such as Figure 1b The mesas shown have inconsistent heights, voids at the bottom, or excessively large vertical channel layer growth defects caused by defects at the top of mesas 1E

In addition, during the ion implantation doping process, because the aspect ratio of the channel hole 2H is too large, the ion implantation range is relatively long. If the verticality of the implantation process is not well controlled, a considerable part of the ions will be incident on the stacked structure 2 On the sidewall, thus affecting the etching selectivity between the sub-layers of the stacked structure 2, so that the active region of the bottom selection transistor deviates from the designed layout, or cannot reach the boss at the bottom of the channel hole 2H due to insufficient implantation energy 1E

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