JPH04315432A - Manufacture of electronic device - Google Patents

Abstract

PURPOSE:To improve device reliability by forming an insulating film having a sloped edge to improve step coverage. CONSTITUTION:An insulating film 12 is formed on a semiconductor substrate, and a resist pattern 14 is formed. The resist pattern is given a sloped edge by baking above 100 deg.C. With this resist pattern used as a mask, the insulating film 12 is etched selectively. The flow rates of etching gases are selected to obtain a selection ratio of 0.8 or 0.4 so that the insulating film can have a sloped edge extending from that of the resist pattern. Since this improves step coverage, metallized interconnections on the insulating film have uniform thickness, thus increasing reliability.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device manufacturing method, and more particularly to an improvement in the electronic device manufacturing method that improves the reliability of metal wiring formed using selective etching.

0002

2. Description of the Related Art Electronic devices have heretofore been manufactured by various methods, and a major problem in each manufacturing method is how to improve the yield.

FIG. 5 shows a method using selective etching, which is a typical conventional electronic device manufacturing method. An insulating film 12 is formed on a semiconductor substrate 10 (FIG. 5(a)).
), a resist is further laminated on the insulating film 12, and etched by photolithography to form a resist pattern 14 (FIG. 5(b)).

Then, the insulating film 12 is etched using the resist pattern 14 as a mask (FIG. 5(c)). Dry etching, which has excellent in-plane uniformity and excellent anisotropic etching, is mainly used for this etching. The etching conditions are set to have an excellent selectivity, that is, to make the etching rate of the insulating film several times higher than the etching rate of the resist.

Finally, the resist is removed and a metal 16 serving as a wiring is formed on the etched insulating film 12 by vapor deposition or the like to manufacture an electronic device (FIG. 5(d)).

[0006]

[Problems to be Solved by the Invention] However, in the conventional electronic device manufacturing method, the insulating film is etched with a high selectivity, resulting in steep edges.
The thickness of the metal in the insulating film gap area indicated by A in Figure 5(d) is very thin compared to other parts, so when current is passed, the current density is increased at this thinner area. There was a problem in that the amount of wire was excessive and there was a risk of wire breakage.

The present invention was made in view of the above-mentioned problems of the prior art, and its purpose is to improve the step coverage at the end of the insulating film of the metal wiring and to prevent the metal wiring from becoming thinner at the end of the insulating film. An object of the present invention is to provide an electronic device manufacturing method that can prevent wire breakage and the like and improve the reliability of the electronic device.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a lamination process in which an insulating film and a resist are sequentially formed on a substrate, and an etching process in which the insulating film is selectively etched using the resist as a mask. a wiring forming process of forming a wiring metal on an etched insulating film; and a sloped part forming process of forming a substantial sloped part at the end of the resist that becomes the mask after the lamination process. is established,
Further, the selective etching selectivity in the etching process is set to a low value of 1.0 or less to form a sloped portion at the end portion of the insulating film.

[0009]

[Operation] In the electronic device manufacturing method of the present invention, a substantial slope is formed at the end of the resist, and in order to reflect this slope in the insulating film, the selection ratio is set low, contrary to the conventional method. Selective etching is performed to form a sloped portion at the end of the insulating film.

When the sloped portion is formed at the end of the insulating film in this manner, the step coverage of the wiring metal formed thereon at the end of the insulating film is improved, and it is possible to obtain a metal having a substantially uniform thickness. becomes possible.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the electronic device manufacturing method according to the present invention will be described below with reference to the drawings.

FIG. 1 shows the manufacturing method of this embodiment. First, as in the conventional manufacturing method, an insulating film 12 such as SiN is formed on a semiconductor substrate 10, and then a photoresist is applied. Then, a resist pattern 14 is formed using photolithography technology.

Next, in this embodiment, baking was performed at 120° C. in order to form a sloped portion 14a at the end of the resist. As is well known, the shape of the edge of a photoresist depends on the baking temperature after development, and when baking is performed at a temperature of 100°C or higher, it begins to melt, and the shape of the edge of the photoresist begins to melt as shown in FIG. 1(b) due to the effect of surface tension. 14a is formed.

In this way, the inclined portion 1 is formed at the end of the resist.
After forming 4a, a selective etching process for the insulating film is performed. In this example, a dry etching method was used because wet etching has problems with side etching and uniformity.

In dry etching, the etching rate is changed by changing the flow rate of the gas used. FIG. 2 shows an experimental example using O2 and CHF3 as reaction gases. In the figure, the horizontal axis represents the flow rate ratio of the reactant gas, the left vertical axis represents the etching rate, and the right vertical axis represents the selectivity (etching rate ratio between the resist and the insulating film). Note that the resist was post-baked at 120°C. As can be seen from the figure, as the ratio of O2 to CHF3 increases, the etching rate of SiN to resist, that is, the selectivity, decreases monotonically, and when the O2 concentration ratio is 10%, the selectivity is about 2.3. When the O2 concentration ratio is 40%, the selection ratio is 0.8, and when the O2 concentration ratio is 60%, the selection ratio is 0.5.

As mentioned above, in conventional selective etching, etching accuracy is improved, that is, precision is achieved by increasing the selectivity ratio, but in this embodiment, the etching accuracy is improved, that is, precision is achieved by increasing the selectivity ratio. By setting this, the slope formed at the end of the resist is reflected in the etched cross section of the insulating film.

Therefore, in this embodiment, the insulating film S
iN 200nm, resist 1μm, baking temperature 1
At 20°C, the selectivity of dry etching is 0.8 and 0.
4, the inclination angles of the inclined portions at the ends of the insulating film could be set to 45 degrees and 20 degrees, respectively.

After forming the sloped portion in the insulating film in this manner, metal for wiring is formed by vapor deposition, as shown in FIG. 1(d).
), it is possible to form a metal wiring having a substantially uniform thickness.

In the above embodiments, the sloped portions were formed at the ends of the resist by baking, but it is also possible to form the sloped portions using other methods.

An example of such a method is shown in FIG. 3, in which an insulating film 12 is formed on a semiconductor substrate 10. When forming a resist pattern, the resist is stacked in a multi-layered manner as shown in FIG. 3 to form a multi-layered structure, and a substantial slope is formed at the end of the resist. Then, by using this multilayer resist 15 and setting the selectivity of the insulating film 12 to a low value in the same manner as in the previous embodiment, a sloped portion can be formed at the end of the insulating film. Further, FIG. 4 shows a manufacturing method of still another embodiment. In this embodiment, after forming the insulating film 12 having a steep edge as in the conventional case,
The resist 18 is applied again. At this time, resist 18
The resist 18 is formed so as to have a difference between the resist 18 and the already etched insulating film 12. Furthermore, this resist 18
A resist 20 is formed thereon, and selective etching is performed.

The resist 20 is inclined at the difference between the insulating film 12 and the resist 18, and therefore the left side in the figure is etched more, so that an inclined part is formed in the insulating film 12.

[0022]

[Effects of the Invention] As explained above, according to the electronic device manufacturing method according to the present invention, it is possible to form a sloped portion at the end of an insulating film, to make metal wiring uniform, and to improve the reliability of an electronic device. It becomes possible to improve the performance.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a graph diagram showing the relationship between the flow rate ratio and selection ratio of reaction gases in the same example.

FIG. 3 is an explanatory diagram of a manufacturing method according to another embodiment of the present invention.

FIG. 4 is an explanatory diagram of a manufacturing method according to another embodiment of the present invention.

FIG. 5 is an explanatory diagram of a conventional manufacturing method.

[Explanation of symbols]

10 Semiconductor substrate 12 Insulating film 14 Resist 15 Multilayer resist 16 Metal 18, 20 Resist

Claims (1)

[Claims] 1. A lamination process in which an insulating film and a resist are sequentially formed on a substrate, an etching process in which the insulating film is selectively etched using the resist as a mask, and a wiring in which a wiring metal is formed on the etched insulating film. In the electronic device manufacturing method including a forming process, a slope forming process is provided for forming a substantial slope at an end of the resist that becomes the mask after the lamination process,
A method for manufacturing an electronic device, characterized in that a selection ratio of selective etching in the etching process is set to a low value of 1.0 or less to form a sloped portion at an end portion of the insulating film.