JPH02208933A - Formation of contact hole - Google Patents

Abstract

PURPOSE:To restrain the occurrence of defect by a method wherein multiple resist films are provided; one resist film is made solution retardant; and then a stepped contact hole is made by transfer process. CONSTITUTION:The first positive resist film 13 is formed to be alkali-processed on a wiring layer 11 through the intermediary of an insulating film 12. Next, the resist film 13 is coated with the second resist film 14 and after heating process, an exposure part 15 is formed by photo lithographic transfer process, etc. Then, the exposure part 15 is developed to form a stepped developed pattern. At this time, the resist film 13 being alkali-processed, a part of a sensitizer is denatured becoming insoluble to delay the development of the resist film 13 layer than that of the resist film 14. Later, a contact hole 17 reaching the wiring layer 11 is made in the insulating part 12 by etching process. Through these procedures, the hole 17 can be easily made by the transfer process so as to restrain the occurrence of defect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming contact holes used in the manufacturing process of, for example, LSIs.

[Conventional technology]

Conventionally, the method for forming this type of contact hole is shown in Figure 3 (
This is carried out through the steps shown in a) to +e). This is shown in the same figure (
It will be explained below based on a) to (e).

First, as shown in FIG. 3A, a positive resist film 3 is formed on a first wiring layer 1 with an insulating film 2 interposed therebetween. next,
By exposing this resist film 3 to light, an exposed area 4 is formed as shown in FIG. form 5.

Then, an undercut 6 is formed in the insulating film 2 by wet etching as shown in the figure (d>), and then a stepped contact hole reaching the wiring layer 1 is formed by anisotropic etching as shown in the figure (el). 7 is formed on the insulating film 2.

In this way, the contact hole 6 can be formed in the insulating film 2.

Thereafter, in order to form a wiring pattern, the resist film 3 is removed as shown in FIG. This is done by forming a second wiring layer 8 connected to the .

By the way, in this type of method for forming contact holes, the contact holes 7 are formed in a step-like manner so that slits 9 as shown in FIG. 4 are not generated during the next step of forming a wiring pattern.

[Problem to be solved by the invention]

However, in the conventional contact hole forming method, a wet etching step is required to form the contact hole 7 in the insulating film 2, which increases the number of steps.
There is a problem in that forming contact holes becomes complicated. Furthermore, the increase in the number of process steps also poses a problem in that foreign matter tends to adhere to the object to be processed during contact hole formation, resulting in a higher rate of defects.

The present invention has been made in view of the above circumstances, and provides a method for forming a contact hole that can easily form a contact hole and can suppress the incidence of defects.

[Means for Solving the Problems] A method for forming a contact hole according to the present invention includes sequentially stacking two types of resist films on a wiring layer via an insulating film, and then exposing and developing these resist films. After forming a resist pattern by etching, a step-like contact hole is formed in the insulating film by etching, and before forming the contact hole, one of the resist films is subjected to a treatment to make it insoluble. It is something.

[For production]

In the present invention, a stepped contact hole can be formed in the insulating film by subjecting one of the upper and lower resist films to a treatment to make it insoluble, exposing it to light, and then etching it.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, the structure etc. of this invention will be explained in detail by the Example shown in the figure.

FIGS. 1(a) to 1(f) are cross-sectional views showing the steps of the pattern forming method according to the present invention. This is shown in Figures (a) to (d).
The following is an explanation based on the following.

First, as shown in FIG. Perform alkali treatment. In this case, the alkali treatment is performed on the insulating film 12.
This is carried out by immersing, for example, an alkaline solution on which the Lujist 13 is applied. Next, a positive type second resist film 14 is coated and heated on the second resist film 14 as shown in +8) C of the same figure, and then transferred using a transfer method such as light or lithography as shown in Figure 8). The exposed portion 15 is formed by the following steps.

Then, by developing the exposed portion 15, a stepped (one character) shaped developed pattern (resist pattern) 16 is formed as shown in FIG. In this case, the first lurgist film 13
is subjected to alkali treatment, and as a result, a part of the photosensitizer is denatured and becomes insolubilized, and the dissolution of the second resist film 13 is suppressed, so that the development of the second resist film 13 is prevented.
It is later than the development of 4. Thereafter, a contact hole 17 reaching the first wiring layer 11 is formed by etching, as shown at td1 in the same figure, after going through the steps shown in +d)A of the same figure.

In this way, contact holes can be formed.

That is, in this embodiment, the upper and lower resist films 13.
After performing alkali treatment on the lower resist film 13 of the resist film 14, it is exposed and etched to form the insulating film 1.
2, a stepped contact hole 17 can be obtained.

Here, the symbols 17a and 14a in FIG. 1+d) are part of the contact hole 17 and the corroded resist layer, and the symbol 12a in FIG. be.

In addition, in order to form the wiring pattern, please refer to FIG.
After removing the resist films 13 and 14 as shown in FIG.
This is done by forming the wiring 1i18 on the insulating film 12.

Now, FIG. 2 (on the left side of the target figure) shows the results of a simulation ANE using five samples, and from this it can be seen that a step has occurred in the final E developed pattern 16. In this case, the distance on the horizontal axis and the thickness on the vertical axis indicate the horizontal and vertical directions of the substrate, respectively. In addition, the symbols A-E are
Development time: 15 seconds, 30 seconds, 45 seconds, 60 seconds, 75 seconds respectively
The resist pattern 15 at the second time is shown.

Furthermore, in this example, an example was shown in which a positive resist is made insoluble by alkali treatment, but in addition to this, the present invention can also make a positive resist to be made insoluble by, for example, irradiation with ultraviolet rays. can.

Furthermore, in this embodiment, a positive type resist)13.
Although the case of using resist No. 14 has been shown, the present invention can also use a negative type resist. In this case, it is necessary to make the upper negative resist of the upper and lower negative resist films difficult to dissolve.

〔Effect of the invention〕

As explained above, according to the present invention, two types of resist films are sequentially laminated on a wiring layer via an insulating film, and then these resist films are exposed and developed to form a resist pattern, and then etched. In this method, a step-like contact hole is formed in an insulating film.Before forming this contact hole, one of the two resist films is subjected to a treatment to make it insoluble, so that a step-like contact hole is formed in the insulating film. Contact holes can be obtained.

Therefore, since the conventional wet etching process is no longer necessary, contact holes can be easily formed. Furthermore, the reduction in the number of steps for forming contact holes makes it possible to prevent foreign matter from adhering to the object to be processed during the formation of contact holes, thereby reducing the rate of defects.

[Brief explanation of the drawing]

1(a) to 1(f) are cross-sectional views for explaining the contact hole forming method according to the present invention, FIG. 2 is a diagram of a developed pattern obtained by sample simulation, and FIG. 3(a)
) to (g) are cross-sectional views for explaining the conventional method of forming contact holes, and FIG. 4 is a cross-sectional view showing an example of a defective wiring pattern. 11...First wiring layer, 12...Insulating film, 13
...Second resist film, 14...Second resist film, 15...Exposed portions 1, 16...Development pattern,
17...Contact hole. Agent Masuo Oiwa Figure 2 Figure 4 Figure 3

Claims (1)

[Claims] Two types of resist films are sequentially laminated on the wiring layer via an insulating film, and then these resist films are exposed and developed to form a resist pattern, and then a stepped contact hole is formed in the insulating film by etching. 1. A method for forming a contact hole, the method comprising: performing a treatment to make one of the resist films insoluble in water before forming the contact hole.