JPH0823078A - Manufacture of programmable element - Google Patents

Abstract

PURPOSE:To manufacture a programmable element which deteriorates scarcely in electrical properties by a method wherein a programmable insulating film is prevented from lessening in thickness when etching is carried out in a window region where a programmable element forming region is formed. CONSTITUTION:A silicon oxide film 16 and an amorphous silicon layer 14 located on a programming insulating film 13 inside a window region 18 where a programmable element is manufactured are etched halfway through a dry etching method and then etched to the end through a wet etching method, whereby the ground programming insulating film 13 is prevented from lessening in thickness due to etching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an electrically programmable programmable element incorporated in a semiconductor integrated circuit device.

[0002]

2. Description of the Related Art Among semiconductor integrated circuit devices, a so-called PROM (Programmable ROM) in which contents can be electrically written after a user purchases is an RO with desired contents.
M (Read Only Memory) is widely used because it can be obtained immediately.

Also in the field of logic circuits, the so-called PLD (Programmable Logic Device), in which the content can be electrically written after the user purchases it, is also possible.
Are used for similar purposes. In order to configure a PROM or PLD, it is necessary to use a programmable element in which the stored contents can be electrically written from the outside and the stored contents are retained even when the power is turned off.

Conventionally, the method of manufacturing such a programmable element has been, for example, as follows. Figure 2
(A)-(d) is a figure which shows the manufacturing method of the programmable element of a prior art example, and demonstrates it with reference to this.

First, as shown in FIG. 2A, an insulating film 3 for programming is formed on the wiring layer 2 located on the silicon oxide film 1 by the existing low pressure vapor deposition method, and then a photoresist layer is formed. 4 and the insulating film 3 for programming is formed by using the existing lithography technology and dry etching technology.
And the wiring layer 2 is patterned.

Subsequently, as shown in FIG. 2B, the photoresist layer 4 is removed, an interlayer insulating film 5 is formed by using the existing vapor phase growth technique, and then a photoresist layer 6 is formed. Similarly, the existing lithography technique and dry etching technique are used to perform the window etching of the window region 7 for manufacturing the programmable element.

Then, as shown in FIG. 2C, the photoresist layer 6 is removed, the wiring layer 8 is formed by using the existing sputtering technique, and then the photoresist layer 9 is formed. The wiring layer 8 is patterned by using the technique and the dry etching technique.

Finally, as shown in FIG. 2D, the photoresist layer 9 is removed to produce a programmable element having the wiring layer 2 as a lower electrode and the wiring layer 8 as an upper electrode.

Programming is performed by applying a voltage of 15 to 20 V between the lower electrode and the upper electrode to break the insulation of the programming insulating film 3.

[0010]

However, in the conventional method for manufacturing a programmable element as described above, since the etching of the window region 7 for manufacturing the programmable element is performed only by the dry etching method, the interlayer insulating film is formed. The program insulating film 3 located immediately below 5 has a drawback that it is thinned by being etched in the latter half of the dry etching and its electrical characteristics are deteriorated.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a programmable element of higher quality which prevents deterioration of the electrical characteristics of the programming insulating film.

[0012]

A method of manufacturing a programmable element according to the present invention for solving the above-mentioned problems, comprises:
In a method of manufacturing a programmable element in which a programming insulating film formed on a semiconductor substrate or a wiring is electrically broken down to perform writing, insulation located in a window region for manufacturing the programmable element and on the programming insulating film There is a step of removing the film by using two kinds of etching techniques, a dry etching method and a wet etching method.

The method also includes the step of forming an amorphous silicon layer in contact with the upper surface of the program insulating film.

[0014]

According to the above-described structure of the present invention, the insulating film located in the window region for forming the programmable element and on the program insulating film is formed by using two kinds of etching techniques, that is, the dry etching method and the wet etching method. Since the wet etching method has a larger selection ratio of the program insulating film than the dry etching method due to the removal step, the dry etching of the underlying program insulating film can be performed while suppressing the expansion of the diameter of the bottom of the window region. It is possible to prevent thinning, and it is possible to suppress deterioration of electrical characteristics such as reduction of withstand voltage of the programming insulating film.

[0015]

An embodiment of the present invention will be described below with reference to the drawings.

1 (a) to 1 (f) show a method of manufacturing a programmable element in an embodiment of the present invention.

As the insulating film, a silicon oxide film or amorphous silicon is used here. First, as shown in FIG. 1A, for example, an aluminum layer and a titanium nitride layer are laminated on the first silicon oxide film 11 of about 600 nm formed by the existing vapor phase growth method. Thickness about 7
The wiring layer 12 having a thickness of 00 nm is formed. A program insulating film 13 having a thickness of about 90 nm and having a structure in which a silicon nitride film, an amorphous silicon film, and a silicon nitride film are sequentially stacked is formed thereon by an existing vapor deposition method. Further, another amorphous silicon layer 14 of about 10 n is also formed on the program insulating film 13 by the existing vapor phase growth method.
m. Then, the first photoresist layer 15 is formed on the amorphous silicon layer 14, and the amorphous silicon layer 14, the programming insulating film 13, and the wiring layer 1 are formed by using the existing lithography technique and dry etching technique.
Pattern 2.

Next, as shown in FIG. 1B, after removing the photoresist layer 15, a second silicon oxide film 16 is grown to a thickness of about 650 nm by, for example, a plasma vapor deposition method, and further. A second photoresist layer 17 is formed on the second silicon oxide film 16, and a window region 18 for forming a programmable element is patterned by using the existing lithography technique.

Subsequently, as shown in FIG. 1C, the amorphous silicon layer 14 which is an insulating film located in the window region 18 for manufacturing the programmable element and on the programming insulating film 13 and the second The second silicon oxide film 16 of the silicon oxide film 16 is etched by a dry etching method. In this embodiment, at this time, the amorphous silicon layer 14 acts as an etching stop layer during dry etching.

Then, as shown in FIG. 1 (d), the remaining amorphous silicon layer 14 which is an insulating film is etched by using a wet etching method to etch the window region 18 for forming a programmable element. Complete. In this embodiment, at this time, the selection ratio between the amorphous silicon layer 14 and the programming insulating film 13 with respect to the wet etching solution is sufficiently large, so that the programming insulating film 13 is hardly etched.

Then, as shown in FIG. 1 (e), the second photoresist layer 17 is removed, and an aluminum layer is laminated on the titanium nitride layer, for example, using an existing sputtering technique to have a thickness of about 600 nm. After forming the second wiring layer 19, the third photoresist layer 20 is formed, and the second wiring layer 19 is patterned by using the existing lithography technique and dry etching technique.

Finally, as shown in FIG. 1 (f), the third photoresist layer 20 is removed to form a programmable element having the wiring layer 12 as a lower electrode and the second wiring layer 19 as an upper electrode. Create.

In the programmable element manufactured by the above method, the program insulating film 13 is not directly etched by the dry etching at the time of window etching as described above. Thin film can be prevented, resulting in 10-15V
It becomes possible to manufacture a programmable element having a stable breakdown voltage.

The silicon oxide film 11, the wiring layer 12 of the programmable element, the program insulating film 13, the amorphous silicon layer 14, the second silicon oxide film 16, and the second wiring used in the above embodiments. The specific film thickness or forming method of the layer 19, the wiring layer 12, and the material of the second wiring layer 19 do not necessarily have to follow the configuration of the embodiment. Also,
The amorphous silicon layer 14 does not necessarily have to be formed as in the embodiment, and may not be formed. Furthermore, the programming insulating film 13 does not necessarily have to be formed on the wiring layer 12 as in the configuration of the embodiment, but may be formed on the diffusion layer formed on the semiconductor substrate.

[0025]

According to the present invention, the insulating film located in the window region for forming the programmable element and on the insulating film for programming is first etched halfway by the dry etching method and the rest is etched by the wet etching method. As a result, it is possible to provide a method of manufacturing a programmable element of higher quality, which prevents the underlying insulating film for programming from being thinned by dry etching and prevents deterioration of the electrical characteristics of the insulating film for programming.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a method of manufacturing a programmable element according to the present invention.

FIG. 2 is a cross-sectional view showing a method of manufacturing a conventional programmable element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicon oxide film 2 Wiring layer 3 Insulating film for programming 4 Photoresist layer 5 Interlayer insulating film 6 Photoresist layer 7 Window region 8 Wiring layer 9 Photoresist layer 11 Silicon oxide film 12 Wiring layer 13 Insulating film for programming 14 Amorphous Silicon layer 15 Photoresist layer 16 Silicon oxide film 17 Photoresist layer 18 Window region 19 Wiring layer 20 Photoresist layer

Claims (2)

[Claims] 1. A method of manufacturing a programmable element, in which a programming insulating film formed on a semiconductor substrate or a wiring is electrically destroyed to perform writing, in a window region for manufacturing the programmable element and in the window region. A method of manufacturing a programmable element, which comprises a step of removing an insulating film located on a program insulating film by using two kinds of etching techniques, a dry etching method and a wet etching method. 2. The method of manufacturing a programmable element according to claim 1, further comprising the step of forming an amorphous silicon layer in contact with an upper surface portion of the programming insulating film.