An Oxide Filling Method for Cutting Lines of Top Select Gate

Abstract

The present invention provides a kind of oxide filling method of top select gate tangent line, by adopting high-density plasma chemical vapor deposition method (HDP-CVD) to fill the oxide material in the top select gate tangent channel, the filled oxide obtained can Effectively resist the harmful etching caused by the removal of fluorine-containing gas during the subsequent tungsten gate formation process, thereby avoiding the formation of etching channels and being filled by tungsten deposition, thus avoiding unnecessary tungsten residues and improving the reliability of the 3D NAND flash memory structure Product performance.

Description

technical field [0001] The present invention relates to the field of semiconductor manufacturing, in particular to a method for manufacturing a 3D NAND flash memory structure, specifically an oxide filling method for a tangential line of a top selection gate that avoids tungsten residues during the formation of subsequent gate lines and tungsten common sources. 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 pursue 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....

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Problems solved by technology

[0013] However, in the above step S6, although atomic layer deposition (ALD) is used for oxide filling, a good filling effect of the top select gate cut trench (Top Select Gate Cut Trench) can be obtained, that is, there is no obvious seam or Void, but the oxide formed by filling in this way has a faster hydrofluoric acid (HF ) Wet etching (Wet Etch) corrosion rate and fluorine-containing gas corrosion rate, so in the subsequent annealing process steps and tungsten gate (W-Gate) formation steps, it is easy to be caused by hydrofluoric acid (HF ) wet etching (Wet Etch) and / or the removal of fluorine-containing gas (Fluorin Outgas), causing the ALD filling oxide 70' to be etched, resulting in butterfly (Disshing) defects in the top area (Top Area), and even Form trench 90 (see Figure 2b ), and the trench 90 is filled with deposited tungsten fill 80 in the subsequent formation step of the tungsten common source (W-ACS) (see Figure 2c ), and in the subsequent tungsten common source (W-ACS) chemical mechanical polishing (CMP), it will also be difficult to remove and become tungsten residue 80’ (W Residue) (see Figure 2d and image 3 ), which directly affects the performance of three-dimensional (3D) flash memory

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