JP3132847B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an element isolation layer of a semiconductor device.

[0002]

2. Description of the Related Art As shown in FIG. 2, a conventional element isolation layer includes an element isolation layer 23, an inversion prevention layer 22, and an
Reference numeral 4 is formed in a plane on the semiconductor surface 21 and has a certain distance and area as an element isolation region.

[0003]

As described above, the conventional device isolation layer has a certain distance and area as a device isolation region on the plane of the semiconductor, so that the size of the semiconductor device can be reduced.
This hindered high integration.

[0004]

A step is formed on the surface of a semiconductor substrate, and an element isolation region is formed on the step.

[0005]

Since the step is used as the element isolation region, the element isolation region can be reduced in plan (on the mask). Further, the element isolation region is formed in a self-aligned manner, and the element isolation region can be reduced to the thickness of the element isolation layer.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the method for manufacturing a nonvolatile semiconductor memory according to the present invention will be described below in detail with reference to the drawings. First, as shown in FIG. 1A, a semiconductor substrate 1 is patterned with a photoresist 2 or the like. The semiconductor substrate 1 refers to a single semiconductor substrate such as silicon or germanium, a compound semiconductor substrate such as gallium arsenide (GaAs), indium phosphide, or a general semiconductor substrate.

Next, as shown in FIG. 1B, the semiconductor substrate 1 in a region 3 patterned with a photoresist 2 or the like is etched. The depth of the semiconductor substrate 1 is the element isolation width in the present invention. As a method of etching the semiconductor substrate 1, there are a dry etching method and a wet etching method. As described above, the etching amount of the semiconductor substrate 1 is determined from the element isolation width.

Next, after removing the photoresist and the like, an insulating film 4 is formed thin as shown in FIG. 1C, and a silicon nitride film 5 is laminated. The insulating film 4 is an insulating film such as a silicon oxide film or a silicon oxynitride film. Desirably, the thickness of the insulating film 4 is between 100 and 1000 degrees. The silicon nitride film 5 serves as an oxidation resistant mask. Therefore, the material may not be a silicon nitride film as long as it is an oxidation resistant material. It is sufficient that the silicon nitride film 5 has no pinholes and has oxidation resistance.
〜１０10000Å. As a method for forming the silicon nitride film 5, there is a chemical vapor deposition method (CVD method) or a physical vapor deposition method (PVD method).

In the silicon nitride film 5 formed by the CVD method or the PVD method, the film laminated on the stepped portion is weaker than the film laminated on the flat portion. Is quickly removed, and the region 6 without the silicon nitride film 5 is formed at the step. As an etching method, isotropic etching is more effective than anisotropic etching. In other words, by performing wet etching or isotropic dry etching,
The silicon nitride film in the flat portion is left, and only the silicon nitride film in the step portion can be etched. In particular, when the silicon nitride film 5 is formed by plasma CVD or sputtering,
Since the film quality of the step portion is particularly weak, the above method works effectively.

Next, as shown in FIG. 1E, an impurity for preventing field inversion is introduced into the region where the silicon nitride film 5 at the step is removed to form an inversion prevention layer 7. As a method for introducing the impurity element, there are an ion implantation method and a diffusion method. Next, as shown in FIG. 1F, the semiconductor substrate 1 is oxidized to form an insulating film 8 for element isolation in the step region 6 where no silicon nitride film 5 exists. When the substrate is silicon, the insulating film 8 for element isolation becomes a silicon oxide film.

Next, the silicon nitride film 5 and the insulating film 4 are removed to obtain FIG. Here, the region not covered with the element isolation insulating film 8 is an active region. Various impurity diffusion layers, transistors and the like are formed in this active region. For example, after forming a thin insulating film 9 as shown in FIG. 2, an impurity diffusion layer 10 is formed by a method such as ion implantation.
Thereafter, a transistor, a wiring, and a protective film are formed to complete a semiconductor device.

[0012]

As described above, according to the method of manufacturing a semiconductor device of the present invention, an element isolation region can be formed at a step formed on the surface of a semiconductor substrate, so that the width and area of an element isolation layer can be reduced. . In particular, in plan view, the width of the element isolation layer can be reduced to the thickness of the element isolation layer. Further, an element isolation region can be formed in a step portion in a self-aligned manner. Therefore,
The greatest effect is achieved for miniaturization and high integration of semiconductor devices.

[Brief description of the drawings]

FIGS. 1A to 1G are cross-sectional views illustrating a semiconductor device according to an embodiment of the present invention in the order of steps; FIGS.

FIG. 2 is a completed diagram of the semiconductor device of the present invention.

FIG. 3 is a sectional view showing element isolation of a conventional semiconductor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Photoresist 4 Insulating film 5 Silicon nitride film 7 Inversion prevention layer 8 Element isolation insulating film 10 Impurity diffusion layer

Claims (1)

(57) [Claims] 1. A photoresist is coated on the surface of a semiconductor substrate.
And turning the surface of the semiconductor substrate to a stepped portion.
And etching into a desired shape having, after removing the photoresist, forming an insulating film on a surface of the semiconductor substrate, forming a silicon nitride film on the insulating film, the silicon Isotropic etch of nitride film
A step of selectively self etched away only the silicon nitride film formed on the stepped portion by ring, before
A step of locally oxidizing the step portion to form an insulating film for element isolation, and a step of removing the silicon nitride film.
A method for manufacturing a semiconductor device, comprising: