Method for producing semiconductor device

Abstract

A method of manufacturing a semiconductor device, comprising exposing a lower electrode (19) made of polycrystalline silicon and having a roughened surface to oxygen plasma (61), forming a silicon oxide film (19a) on the surface of the lower electrode (19), By exposing the lower electrode (19) on which the silicon oxide film (19a) is formed to nitrogen plasma (62), the surface of the silicon oxide film (19a) and its vicinity are modified into a silicon nitride film (19b). Next, a capacitive insulating film (20) made of tantalum oxide is formed on the lower electrode (19) on which the silicon nitride film (19b) is formed, and then the capacitive insulating film (20) is exposed to oxygen plasma (63) , oxygen is supplied to the capacitive insulating film (20). Next, the capacitive insulating film (20) is heat-treated in an oxidative atmosphere to crystallize it, and then an upper electrode (21) is formed on the crystallized capacitive insulating film (20).

Description

technical field [0001] The present invention relates to a metal-insulator-semiconductor (MIS) structure in which a metal is used for the upper electrode and a semiconductor for the lower electrode, or a metal-insulator-metal (MIM) structure in which metal is used for both the upper electrode and the lower electrode. A method of manufacturing a semiconductor device that constitutes a capacitor element, particularly a capacitor element of a memory cell, such as a DRAM (Dynamic Random Access Memory) device. Background technique [0002] In a DRAM device, along with an increase in memory capacity, miniaturization of memory cells and peripheral circuits is required. Therefore, the dedicated area of ​​the capacitive elements constituting the memory cells is reduced, and as a result, how to secure the electrostatic capacitance for storing charges in each capacitive element becomes a problem. [0003] Therefore, in order to increase the surface area of ​​the electrode constituting ...

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Problems solved by technology

This local non-uniformity of film thickness causes increase or decrease of leakage current in capacitive element, shift of electrostatic capacitance and deterioration of reliability

[0018] Second, although the film thickness of the thermal silicon nitride film 108a based on the thermal nitridation of RTN is an important parameter governing the leakage current flowing through the capacitor element and the reliability of the capacitor element, there is a problem that the film thickness can only be formed in the range of 1nm to 1nm. Problems around 1.5nm

[0019] Thirdly, in the process of removing organic carbon after film formation of the capacitive insulating film 109 made of tantalum oxide and supplying oxygen with a near-stoichiometric composition, from the viewpoint of the crystallization of tantalum oxide, it takes about 60 seconds at 725°C. The heat treatment is sufficient, but from the point of view of oxygen supply, higher temperature is required

Accordingly, adding the silicon oxide film 108b having a dielectric constant smaller than tantalum oxide in series on the film thickness of the capacitive insulating film 109 has a problem that the capacitance of the capacitive element is greatly reduced.

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