JPH0294661A - Capacity element of integrated circuit - Google Patents

Abstract

PURPOSE:To enhance utilization efficiency of a plane by a method wherein a protruding body composed of an insulator is formed on a semiconductor substrate and metal layers to be used as counter electrodes of a capacity element are formed so as to sandwich a dielectric substance. CONSTITUTION:A silicon substrate 1 is covered with a surface-insulating silicon oxide film 2; silicon nitride films 3 and silicon oxide films 4 are piled up alternately to be quadruple; a laminated body is formed; the laminated body on the silicon oxide film 2 is etched and removed; a protruding body having a quadruply laminated structure of the silicon nitride films 3 and the silicon oxide films 4 is formed. Then, the silicon nitride films 3 of this protruding body are side-etched selectively; the silicon nitride films 3 are shaved off from their side faces toward their inside; side faces of the protruding body are formed to be story-shaped protruding and recessed faces. In addition, an aluminum layer 5, a dielectric-layer silicon oxide film 6 and an aluminum layer 7 are formed on raw faces of the protruding body whose side faces have been made to be the protruding and recessed faces; the aluminum layers 5, 7 are used as counter electrodes. Thereby, it is possible to reduce an area occupied by a capacity element.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a capacitive element of a monolithic integrated circuit formed on a semiconductor substrate.

[Conventional technology]

Conventionally, as a capacitor element formed on a semiconductor substrate, there are a single-layer MOS capacitor for boat fishing, and a planar structure capacitor element whose dielectric is an insulator having a large ε (relative permittivity). In addition, a structure in which a trench is dug on a substrate using silicon trench technology and a conductor-insulator-conductor structure layer is provided on the surface of the trench has recently been reported as a capacitive element with increased capacitance per unit area of the substrate.

[Problem to be solved by the invention]

In the above-described capacitive element structure, a single-layer capacitive element does not have good planar utilization efficiency. Furthermore, even in a capacitive element using a dielectric material with a large ε, the variation in ε is large and stability is lacking. Further, in a trench-drilling type capacitor element, it is necessary to trench the trench vertically, but there is a limit to the depth at that time, and there is a drawback that there is a limit to the planar utilization efficiency.

[Means to solve the problem]

In order to solve the above problem, the present invention provides a semiconductor substrate with an insulating convex body with a layered uneven surface on its side surface, and a metal layer is formed on the surface of the convex body with a dielectric material in between. A capacitive element is formed with this metal layer as a counter electrode.

〔Example〕

Next, the present invention will be explained by examples.

FIG. 1 is a partial cross-sectional view of one embodiment of the present invention.

In FIG. 1, a silicon substrate 1 is covered with a surface insulating silicon oxide film 2, and a silicon oxide film 2 with a thickness of 800 mm, for example, is coated on top of the silicon oxide film 2.
0 silicon nitride films 3 and silicon oxide films 4 are alternately stacked in four layers to form a laminate, and then the required portions are masked and the laminate on the silicon oxide film 2 is removed by etching. A convex body having a quadruple laminated structure of silicon nitride film 3 and silicon oxide film 4 is formed. Next, by performing selective side etching on the silicon nitride film 3 of the convex body, the silicon nitride film 3 portion is scraped inward from the side surface, and the side surface of the convex body becomes a layered uneven surface. ,
A significant increase in surface area can be obtained compared to before side etching. Next, for example, an aluminum layer 5 with a thickness of 1000 mm, a dielectric layer silicon oxide film 6 with a thickness of <1000 mm, and an aluminum layer 7 with a thickness of <1000 mm are formed on the bare surface of the convex body with uneven side surfaces. However, it is a capacitive element with aluminum layers 5 and 7 as opposing electrodes.

[Effects of the Invention] As described above, the capacitive element according to the present invention makes it possible to reduce the area occupied by the capacitive element on a monolithic integrated circuit board to at least 1/2 to 1/3 compared to the conventional one. effective.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of one embodiment of the present invention. 1...Silicon substrate, 2...Silicon oxide film on the upper surface of the substrate, 3...Silicon nitride film of the stack, 4...Silicon oxide of the stack membrane, 5,7
...Aluminum layer for electrode, 6...Dielectric layer silicon oxide film. Agent Patent Attorney Susumu Uchihara

Claims (1)

[Claims] A convex body made of an insulator with a layered uneven surface is formed on a semiconductor substrate, and a metal layer that becomes a counter electrode of a capacitive element is coated with a dielectric material on the surface of the convex body. A capacitive element of a monolithic integrated circuit characterized in that it is formed by sandwiching the element between the elements.