DRAM and forming method thereof

Abstract

The invention discloses a DRAM and a forming method thereof. The forming method of the DRAM comprises the steps of: providing a semiconductor substrate, and forming a plurality of discrete active regions on the semiconductor substrate; etching the active region, and forming a word line trench in the active region; forming a silicon nitride layer on the side wall and the bottom surface of the word line trench through a deposition process; completely oxidizing the silicon nitride layer, and forming a silicon oxide layer on the side wall and the bottom surface of the word line trench; and forming a word line on the silicon oxide layer. The formed word line silicon oxide layer is obtained by completely oxidizing the silicon nitride layer, so that silicon in the source region and the drain region on the two sides of the word line trench is not consumed, the thickness of the formed silicon oxide layer is determined by the thickness of the silicon nitride layer, the stability of the thickness of the silicon oxide layer is ensured, and therefore, the turn-on current of the trench-type transistor under the same turn-on voltage is not reduced.

Description

technical field [0001] The invention relates to the field of memory, in particular to a DRAM and a forming method thereof. Background technique [0002] Dynamic Random Access Memory (Dynamic Random Access Memory, DRAM) is a semiconductor storage device commonly used in computers, and is composed of many repeated storage units. Each memory cell usually includes a capacitor and a transistor. The gate of the transistor is connected to the word line, the drain is connected to the bit line, and the source is connected to the capacitor. The voltage signal on the word line can control the opening or closing of the transistor, and then through the bit line Read the data information stored in the capacitor, or write the data information into the capacitor through the bit line for storage. [0003] In order to improve the integration of the storage structure, the transistors in the dynamic random access memory (DRAM) usually adopt a trench-type transistor structure. The gate of the t...

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Problems solved by technology

[0004] The existing trench transistors of dynamic random access memory (DRAM) will consume the substrate in the process of forming the gate dielectric layer, and the quality of the gate dielectric layer is poor, and there is a problem that the turn-on current drops

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