DRAM (Dynamic Random Access Memory) structure with expansion groove and manufacturing method thereof

Abstract

The invention discloses a DRAM (Dynamic Random Access Memory) structure with an expansion groove and a manufacturing method thereof. The structure comprises an NMOS (N-channel Metal Oxide Semiconductor) transistor and a groove capacitor connected with a source electrode thereof, wherein the groove capacitor comprises a semiconductor substrate, an N-type SiGe layer and an N-type Si layer which are alternately arranged, a groove, a dielectric layer and a polysilicon layer, wherein the groove is located in the N-type SiGe layer and the N-type Si layer which are alternately arranged and extends into the semiconductor substrate, and the section of a side wall of the groove is in a comb tooth shape; the N-type SiGe layer and the N-type Si layer which are alternately arranged are utilized as a lower pole plate; the dielectric layer is located at the surface of the inner wall of the groove; the polysilicon layer is filled in the groove and utilized as an upper pole plate of the groove capacitor; a P-type Si layer is also prepared on the N-type SiGe layer and the N-type Si layer which are alternately arranged; and the NMOS transistor is manufactured on the P-type Si layer. Through the method, the N-type SiGe layer and the N-type Si layer are alternately grown by utilizing a doping and epitaxial technique and the side wall in the comb tooth shape is manufactured by utilizing selective etching; and the method improves the structure of a deep groove capacitor in the DRAM and simplifies the manufacturing process.

Description

technical field [0001] The invention relates to a dynamic random access memory (DRAM, Dynamic Random Access Memory) unit structure and a manufacturing process thereof, in particular to a DRAM unit structure with extended grooves and a manufacturing process thereof, belonging to the technical field of semiconductor manufacturing. Background technique [0002] Currently, the industry generally adopts a 1T1C (one transistor with one capacitor) structure as a DRAM unit. This combination of 1T1C components makes the storage bit of DRAM the electronic component with the highest density and the lowest unit manufacturing cost, and has an irreplaceable position in computer access devices. With the rapid development of semiconductor technology, DRAM components are rapidly developing towards high density and high capacity. How to design a capacitor with equivalent capacitance while the area of ​​the unit element is continuously reduced is one of the most important challenges in DRAM t...

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Problems solved by technology

[0004] However, the deep trench capacitors in this kind of DRAM still face many difficulties in the process: (1) In order to meet the capacitance requirements, the groove depth is required to be very deep, that is, there is a high aspect ratio etching requirement, and there will be The etch rate decline effect (lag effect), so the requirements for the etching process are very high; (2) The lower plate of the capacitor adopts the buried substrate (BP, Buried Plate) process, which is complex and difficult; (3) In order to meet the capacitance requirements, the dielectric layer is required to be very thin, which has the risk of increased leakage and affects the yield

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