Method for manufacturing flash memory floating gate

Abstract

The invention discloses a method for manufacturing a flash floating gate, a bowl-shaped groove of the floating gate is formed by isotropic dry etching with the help of a photoresist mask; then silicon dioxide is deposited in the bowl-shaped groove, the silicon dioxide which is positioned at the outside of the bowl-shaped groove is removed by using the chemical polishing method, thereby forming the floating gate; and then polycrystalline silicon which is positioned out of a flash unit is removed by the self-alignment mode with the help of the dry etching to form the acute periphery of the floating gate, thereby ensuring the floating gate structure not to be affected by other operations during the manufacturing process of the flash, further improving the production efficiency and leading the process to be easy in the optimization of the tip of the floating gate and have smaller fluctuations. The method can reduce the erase failure and reduce the erase voltage in the implementation of the erase action of the flash, thereby leading the flash unit to be easier to control.

Description

technical field [0001] The invention relates to the field of flash memory manufacturing, in particular to a method for manufacturing a flash memory floating gate. Background technique [0002] A flash memory with a floating gate structure usually uses polysilicon with a tip as a floating gate, and the tip of the floating gate is covered by a control gate. When erasing the flash memory, by connecting the source and drain to a low voltage and the control gate to a high voltage, the electrons in the floating gate will tunnel through the gap between the floating gate and the control gate due to the high electric field near the tip of the floating gate. The oxide layer flows to the control gate. In the manufacturing process of the existing floating gate structure flash memory, the tip of the floating gate is usually formed by the local field oxidation method. This method has many subsequent steps that affect the shape of the tip, so it will lead to low production efficiency and ...

AI Technical Summary

Problems solved by technology

In the manufacturing process of the existing floating gate structure flash memory, the tip of the floating gate is usually formed by the local field oxidation method. This method has many subsequent steps that affect the shape of the tip, so it will lead to low production efficiency and is not easy to damage the tip. Optimized, and when the flash memory is erased, the efficiency is easily affected and the erase is incomplete

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