Ion doping method for memory cell in DRAM

Abstract

The invention relates to an ion doping method for a memory cell in a DRAM. The memory cell is provided with an active area produced in a silicon substrate and a plurality of doping structural word lines positioned on the surface of the active area in the silicon substrate. The method comprises the following steps: 1, oxidizing the surfaces and the side walls of the doping structural word lines and the surface of the silicon substrate among the doping structural word lines; 2, coating photoresists on the oxidized surfaces of the doping structural word lines and the oxidized surface of the silicon substrate; 3, removing the photoresists on the oxidized surface of the pre-doped silicon substrate among the doping structural word lines; and 4, filling pre-doping ions into the active area in the silicon substrate of which the photoresists are removed among the doping structural word lines. By oxidizing the surface of the memory cell directly before coating the photoresists, the ion doping method for the memory cell in the DRAM improves the adhesion of the memory cell with the photoresists and the uniformity of the photoresists, and solves the problems of poor adhesion of the photoresists and the surface of the memory cell and reduction of DRAM refreshing time caused by the poor adhesion in the conventional doping methods.

Description

technical field [0001] The invention relates to the field of manufacturing methods of dynamic random access memory (hereinafter referred to as DRAM), in particular to an ion doping method of memory cells in DRAM. Background technique [0002] With the development of the DRAM integrated manufacturing process, the critical dimension (Critical Dimension, CD) of each storage cell capacitor in the DRAM is also continuously reduced. The continuous shrinking of the size of the capacitor CD means that the capacitance value of the storage unit will continue to shrink. The development goal of DRAM market competition is to require the continuous increase of DRAM refresh time (Refresh Time) in order to reduce the refresh frequency of DRAM. However, the reduction of the capacitance value of DRAM storage unit runs counter to the development requirements of DRAM. Therefore, as the CD value of the storage unit capacitance in DRAM decreases, in order to meet the development requirements of ...

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is to provide an ion doping method for memory cells in DRAM to solve the problem of poor adhesion between photoresist and doped structure word line sidewalls and silicon substrate surface in the ion doping process of traditional memory cells

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