Technology of improving ion implantation and boron element diffusion in silicon epitaxial growth

Abstract

The invention provides technology of improving ion implantation and boron element diffusion in silicon epitaxial growth in 3D NAND flash memory structure. Through adopting air having F and / or CI, plasma processing is conducted on a silicon groove interface in silicon epitaxial growth, and thereby monocrystalline silicon in silicon epitaxial growth interface can be effectively damaged and then willbe converted into amorphous silicon. As the epitaxial growing speed of the amorphous silicon interface is lower than that of the monocrystalline silicon interface, the forming of a vacancy (Void) between a silicon epitaxial layer and a substrate can be facilitated. The formed vacancy (Void) becomes a barrier of boron element interface diffusion, which effectively blocks the boron element doped during ion implantation from diffusing to the silicon substrate from the silicon epitaxial layer. Accordingly, the characteristic of the threshold-voltage (vt) of the silicon epitaxial layer can be improved, and the integral performance of the 3D NAND flash memory can be finally enhanced.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a 3D NAND flash memory structure and a manufacturing method thereof, in particular to a process capable of improving the diffusion of ion-implanted boron elements in silicon epitaxy. Background technique [0002] With the development of planar flash memory, the production process of semiconductors has made great progress. However, in recent years, the development of planar flash memory has encountered various challenges: physical limits, existing development technology limits, and storage electron density limits. In this context, in order to solve the difficulties encountered in planar flash memory and to seek lower production costs per unit storage unit, various three-dimensional (3D) flash memory structures have emerged, such as 3D NOR (3D or not) flash memory and 3D NAND (3D NAND) flash memory. [0003] Wherein, in the 3D flash memory of the NOR structure, memory c...

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Problems solved by technology

[0009] After the above process, deposition and etching processes such as ONOP (oxide / nitride / oxide / polysilicon) may be required. These subsequent process steps will generate a lot of heat and form a high-temperature process, and due to the doped boron element The atomic number is the first and the molecular weight is small, so it is very easy to diffuse in these subsequent high-temperature processes, so that it can cross the interface between the silicon epitaxial layer and the substrate, and run from the silicon epitaxial layer to the silicon substrate (see Figure 2a -b, Figure 2a The white arrow in the middle and bottom is the direction of boron element diffusion), which affects the control of the threshold voltage (Vt), and finally affects the performance of 3D NAND flash memory

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