Method for Improving Coupling Coefficient of Control Gate to Floating Gate in Split Gate Flash Memory

Abstract

The invention provides a method for improving the coupling coefficient of the control gate to the floating gate in the split-gate flash memory. A flash memory cell array composed of a flash memory split gate structure is formed on the substrate, and the outermost side of each row of the flash memory cell array is formed with a connection contact hole unit arranged in a shallow trench isolation region; each row of flash memory split gate The corresponding control gates of the gate structure of the unit structure are connected together; the gate structure of the connection contact hole unit is formed with control polysilicon connected to the control gate of the flash memory split gate unit structure in the row; the connection contact hole The oxide layer on the substrate surface of the unit is etched to expose the control polysilicon, and the oxide layer on the substrate surface of the flash memory split-gate unit structure is retained; the gate structure of the flash memory split-gate unit structure and the gate connected to the contact hole unit Interconnected connection sidewalls are formed on both sides of the pole structure, and the connection sidewalls are arranged on the surface of the exposed control polysilicon of the connection contact hole unit, and are arranged on the oxide layer on the substrate surface of the flash memory split-gate unit structure.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, and more specifically, the invention relates to a method for improving the coupling coefficient of a control gate to a floating gate in a split-gate flash memory. Background technique [0002] Flash memory has become a research hotspot in non-volatile memory due to its convenience, high storage density, and good reliability. Since the first flash memory product came out in the 1980s, with the development of technology and the storage needs of various electronic products, flash memory has been widely used in mobile and communication devices such as mobile phones, notebooks, handheld computers and U disks. . Generally speaking, flash memory has a split gate structure or a stacked gate structure or a combination of the two structures. Due to its special structure, split-gate flash memory shows its unique performance advantages in programming and erasing compared with stacked-gate flash m...

AI Technical Summary

Problems solved by technology

[0005] However, the control gate is shorter than the floating gate in the split-gate cell structure of the flash memory according to the prior art, such as figure 1 As shown, thereby reducing the coupling coefficient between the control gate and the floating gate, that is, the coupling coefficient between the first floating gate 520 and the first control gate 510 and the coupling between the second floating gate 620 and the second control gate 610 coefficient

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