Split gate type flash memory and forming method thereof

Abstract

The invention discloses a split gate type flash memory which comprises a semiconductor substrate, a word line, two discrete storage bit units and oxidation layers, wherein the word line is located at the bottom surface of the semiconductor substrate; the two storage bit units are located at two sides of the word line; the oxidation layers are arranged between the two storage bit units and the word line; each storage bit unit comprises a first insulation layer which is located on the bottom surface of the semiconductor substrate, a floating gate which is located on the surface of the first insulation layer, a second insulation layer which is located on the surface of the floating gate, a control gate which is located on the surface of the second insulation layer and a side wall structure which covers the floating gate and the control gate; each floating gate comprises a first floating gate and a second floating gate; and the distance between each first floating gate and the word line is greater than the distance between each second floating gate and the word line. The distance between the first floating gates and the word line is greater than the distance in the prior art, so that the coupling capacitance between the floating gates and the word line is smaller than the capacitance in the prior art, the coupling capacitance between the word line and the floating gates is as small as possible and then the erasing efficiency and the read-write efficiency of the flash memory are improved.

Description

technical field [0001] The invention relates to semiconductor technology, in particular to a split-gate flash memory and a forming method thereof. Background technique [0002] In the existing technology, flash memory (Flash) memory has become the mainstream of non-volatile semiconductor storage technology. Among various flash memory devices, there are basically two types: stacked gate flash memory and split gate flash memory. Since stacked-gate flash memory has over-erasing problems, a control gate of split-gate flash memory is also used as a select transistor (Select transistor), which effectively avoids over-erasing effects, and the circuit design is relatively simple. Moreover, compared with stacked-gate flash memory, split-gate flash memory uses source hot electron injection for programming, which has higher programming efficiency, so it is widely used in various electronic devices such as smart cards, SIM cards, microcontrollers, and mobile phones. product. [0003] ...

AI Technical Summary

Problems solved by technology

[0004] However, the existing split-gate flash memory does not work well

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