Method for increasing contact window in stair region by ion implantation

Abstract

The invention relates to a method for increasing a contact window in a stair region by ion implantation. The method comprises the following steps: forming a stair stack; carrying out stair etching onthe stair stack to form a stair region; carrying out ion implantation on the stair region and forming implanted oxide layers and implanted nitride layers that are distributed in a stair manner in thestair region; and carrying out filling and replacement on the stair region after ion implantation. According to the invention, the rate of wet etching at the step is increased by ion implantation, thesize after silicon nitride removing is increased and thus the thickness of the tungsten layer at the step is increased; the process window is enlarged; the number of times of masking is reduced; andthe production cost is lowered. With the method provided by the invention, the metal thickness of the word line at the stair stack area is increased; the process window is increased by using a simplemethod; and the production cost is reduced.

Description

technical field [0001] The invention relates to a method for enlarging a contact window in a stepped region by using ion implantation, and relates to the technical field of 3D NAND memory manufacturing. Background technique [0002] Since the contact structure of 3D NAND needs to penetrate multi-layer films and stop at different interfaces, due to the uniformity of word lines in the actual etching process, contacts of different depths need to be disassembled for processing (such as figure 2 shown). like figure 1 As shown, the thickness of the word line in the 3D NAND step area is uniform, so using the same mask as a contact and etching to different heights will easily lead to wear and tear (the circled part on the upper right). In view of the situation that the thickness of the word line is required to be smaller and smaller in the future development, it is expected to be more difficult to use a mask to achieve the definition of multi-layer contacts. Contents of the inv...

AI Technical Summary

Problems solved by technology

like figure 1 As shown, the thickness of the word line in the 3D NAND step area is uniform, so using the same mask as a contact and etching to different heights will easily lead to wear and tear (the circled part on the upper right)

In view of the fact that the word line thickness is getting smaller and smaller in future development, it is expected to be more difficult to use a mask to achieve the definition of multi-layer contacts

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