JPH03211733A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To effectively form a micro opening by comparing with the formation of an opening immediately like prior art by allowing a pattern film to remain on a part to be opened in a flattened layer. CONSTITUTION:After an Al layer 11 is formed on an SiO2 film 10 as a lower layer insulating film on an Si substrate 9, a PSG film 12 is formed as an interlayer insulating film, and coated with liquid novolac resin to form a resin layer (flattened layer) 13. After the layer 13 is cured, it is coated with liquid novolac positive photoresist to form a photoresist film (pattern film) 14, and thermally cured. Then, a part to be formed with an opening of the layer 13 is removed, and a positive photoresist film 14 is selectively exposed. Then, when the film 14 of the part emitted with a light is removed, the film 14 remains on the part to be opened in the layer 13.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for manufacturing a semiconductor device, more specifically, a semiconductor device including a step of forming an etching mask for forming an opening such as a contact hole in an insulating film between the eyebrows or the like. The purpose of the present invention is to provide a method for manufacturing a semiconductor device that can form finer openings, and includes a step of forming a pattern film on a planarization layer formed on a substrate, and a step of forming a pattern film on a planarization layer formed on a substrate. a step of buttering the patterned film to leave the patterned film where openings in the planarization layer are to be formed, and applying an etching-resistant material on the entire surface to a thickness thinner than the patterned film on the planarization layer. a step of forming an etching-resistant film with a certain thickness; a step of selectively removing the remaining pattern film using the etching-resistant film as a mask to form an opening; and a step of forming an etching-resistant film with a certain thickness; selectively removing the planarization layer at the bottom of the opening to form an opening in the planarization layer.

[Industrial application field]

The present invention relates to a method of manufacturing a semiconductor device, and more specifically, to a method of manufacturing a semiconductor device including a step of forming an etching mask for forming an opening such as a contact hole in an insulating film between the eyebrows or the like.

[Conventional technology]

Conventionally, when forming an etching mask using a resist film to form an opening such as a contact hole in an insulating film between the eyebrows on an SI substrate, exposure light is It was difficult to form minute openings because the resist film was not irradiated with reflected light of negative intensity.

In order to solve this problem, a method as shown in FIG. 2 is used.

That is, first, as shown in the same figure (a), A1 wiring 3 and this! After forming a light-absorbing resin layer 5 on the uneven surface of the Si substrate 1 on which PSG@4 or the like is formed as a glabellar insulating film covering the wiring 3 and flattening the surface, an intermediate layer is formed on the surface of the Si substrate 1. SOG film 6 and photoresist! ! ! 7 are sequentially formed. Note that 5OGl 16 is used as a mask for etching the underlying resin layer 5 and PSG film 4, and when forming the resist film 7, the resin layer 5 is added to the resist solvent.
It is used to prevent elution of

Next, this resist film 7 was selectively exposed (FIG. (b)
)) After that, the exposed portion of the resist 1117 is removed to form the opening 7a (FIG. 3(C)).

Next, using the resist film 7 as a mask, the openings 7 are selectively formed.
After removing the SOG film 6 at the bottom of a (FIG. c)), the remaining resist film 7 is removed.

Next, using the SOG film 6 as a mask, the underlying resin layer 5 is selectively removed to create an etching mask for forming a contact hole in the PSG film 4 (see Fig.
)).

Thereafter, using this as a mask, the underlying PSG film 4 is removed to complete the contact hole 4a (FIG. 4(f)).

In addition, in FIGS. 2(a) to (f), 2 represents the Si substrate 1.
An SiO□ film is used as an upper lower layer insulating film, and an AI wiring 3 is formed on this SiO□ film 2. Also, the same figure (b
) is a mask on which a mask pattern 8a for selectively exposing the resist film 7 is formed.

(Problems to be Solved by the Invention) Incidentally, in order to further increase the density of semiconductor devices, it is necessary to further miniaturize openings such as contact holes 4a.

However, in order to form an opening with a width of submicron or half micron, as shown in FIG. 2(b), when the opening is formed in the resist film 7 by an exposure method, the exposure due to the diffraction phenomenon of light occurs. Forming fine apertures with high precision is necessary because the contrast in light intensity between areas that should be exposed and areas that should not be exposed may be reduced, or the width of the exposed area may be wider than the desired predetermined width. In addition, if the width of the mask pattern 8a is designed to be small in order to compensate for this spread, the contrast of the light intensity will further decrease during exposure, causing openings in the resist film 7. There is a problem that it becomes difficult to form a part.

SUMMARY OF THE INVENTION The present invention has been made in view of these conventional problems, and it is an object of the present invention to provide a method for manufacturing a semiconductor device that can form finer openings.

[Means to solve the problem]

As shown in FIGS. 1(a) to 1(f), the above problem is solved in the process of forming a patterned film 14 having a first thickness on a planarization layer I3 formed on a substrate 17 (see FIGS. 1(a) to 1(f)). a)), the step of patterning the pattern film 14 to leave the pattern film 14 in the place where the opening of the planarization 1113 is to be formed (FIGS. 11B and 1C), and An etching-resistant material 11A16 is applied on the planarization 1113 to a thickness thinner than that of the pattern film 14.
((d) in the same figure), and a step ((e) in the same figure) of selectively removing the remaining pattern film 14 using the etching-resistant film 16 as a mask to form an opening 16a ((e) in the same figure).
)) and a step of selectively removing the planarization layer 13 at the bottom of the opening 16a using the etching-resistant film 16 as a mask to form an opening 16b in the planarization layer 13 (see FIG.
) is achieved by a method for manufacturing a semiconductor device.

(Function) In the method for manufacturing a semiconductor device of the present invention, the planarization layer 1
The pattern film 14 remains where the openings No. 3 are to be formed. For example, when a positive photoresist film is used as the pattern film 14, when exposing the positive photoresist film, the light is not irradiated to the part where the opening of the resin layer 13 is to be formed, but is irradiated to other parts. The positive photoresist film can remain.

Therefore, in the conventional case, it was necessary to narrow the width of the mask pattern in order to form an opening with a predetermined target width, but in the manufacturing method of the present invention, the opening Since the width of the region to be formed that is not irradiated with light becomes narrower due to the diffraction phenomenon of light, by making the width of the mask pattern slightly wider, the width of the opening can be formed to the target value. Therefore, formation of the opening becomes easy.

In addition, compared to conventional methods in which predetermined openings are punched out and formed as is, the openings are formed where the positive photoresist film remains, so even if the contrast of light intensity is reduced, Even if the positive photoresist film remains,
The formation of the opening becomes more reliable. Furthermore, since the opening is always smaller than the designed width of the opening, it is suitable for miniaturization.

This makes it easier to form finer openings than in the conventional case.

Furthermore, since the remaining pattern film 14 can be used to form an etching mask in a self-aligned manner,
The photo process only needs to be done once, so there is no increase in the number of steps compared to conventional methods, and there is no need for labor.

〔Example〕

Embodiments of the present invention will be specifically described below with reference to the drawings.

FIGS. 1(a) to 1(g) show an example in which the method for manufacturing a semiconductor device including the method for forming an etching mask according to the embodiment of the present invention is applied to the case where an opening for a contact is formed in an interlayer insulating film. FIG.

First, as shown in FIG. 5A, after forming the second AI wiring 11 on the SiO2 film 1o as the lower layer insulating film on the Si substrate 9, a PSG film as an interlayer insulating film with a film thickness of approximately 5 mm is formed.
A film 12 is formed.

Subsequently, a liquid novolak resin is applied by a spin coating method to cover the PSG film 12 and the AI wiring 11 to form a resin layer (flattening layer) 13 having a thickness of 1 to 2 μm. This resin layer 13 is formed to flatten the surface of the Si substrate 9, which has irregularities due to the formation of the A1 wiring 11, and to absorb light for exposure. As a result, when exposing the positive photoresist film to be formed later, the intensity of the exposure light irradiated to the positive photoresist film is kept uniform by absorbing the light reflected at the step between the unevenness on the Si substrate 9.
It becomes possible to perform exposure with high precision.

Next, in order to prevent the resin layer 13 from eluting into the solvent of the positive photoresist formed on the resin N13, the resin layer 13 is cured by heating at 250 to 270"C, and then a liquid novolak-based A positive photoresist l!!I (patterned film) 14 having a film thickness of 1 μm is formed by applying a positive photoresist of 1 μm onto the resin layer 13 by a spin coating method.

Then, it is heat cured at 90°C.

Next, using a mask 5, a resin layer 1 with a width of about 0.5 μm is formed.
The positive photoresist film 14 is selectively exposed except where the opening 13a of No. 3 is to be formed (FIG. 3(b)).
), at this time, the width of the area that should not be exposed becomes narrower than the predetermined width due to the light diffraction phenomenon, but mask pattern 1
By designing the width of 5a to be a little wider, it becomes possible to leave the positive resist film 14 having the target width.

Next, when the positive photoresist film 14 in the irradiated portions is removed by immersion in a developer consisting of an aqueous solution containing 2.38% TMAH (tetramethylammonium hydroxide) for about 60 seconds, the openings in the resin layer 13 are removed. The positive photoresist film 14 remains where the film 13a should be formed (FIG. 3(C)).

Subsequently, the base resin layer 13 is covered with liquid silanol-based SO which serves as a mask for forming openings in the PSG film 12.
G (Spin On Glass) is applied by a spin coating method, and then heated and cured at 200 to 250°C to form an SOG film (etching resistant film) 15 with a thickness of about 0.2 μm (see the same figure). (d)).

Next, when the remaining positive photoresist film 14 is removed using a xylene-based solvent, an opening 16a of the SOG film 16 is formed at the removal site (FIG. 4(e)).

Next, RIE is performed using the remaining SoG film 16 as a mask.
Anisotropic etching is performed using a (reactive ion etching) method to etch and remove the resin layer 13 at the bottom of the opening 16a. As a result, the PSG film 12 is exposed ((f) in the same figure).

Next, 0□ gas is introduced into the decompression chamber, and the pressure is 10o.
Same aperture 1 under +mTorr, power 300W conditions
．． The contact hole 12a is completed by selectively etching and removing the PSG film 12 through the contact hole 6a by the RrE method (FIG. 6(g)).

As described above, in the embodiment of the present invention, FIG.
), when exposing the positive photoresist film 14, the light is not irradiated to the area where the opening 13b of the resin layer 13 shown in FIG. I have to. Therefore, in contrast to the conventional case where it was necessary to narrow the width of the mask pattern 15a in order to form an opening in the resin layer with a predetermined width, in the embodiment, the width of the mask pattern 15a was slightly narrowed. By making it wide, the width of the opening 16a can be formed to a target value. Therefore, unlike the conventional case, the light intensity does not decrease at the opening, and therefore the opening 1 of the resin layer 13
3a can be formed easily and accurately.

Also, compared to the conventional case of forming an opening,
In the embodiment of the present invention, as shown in FIGS. 1(d) to (f), the openings 13a of the resin layer 13 are formed where the positive photoresist film 14 remains, so even if the light intensity is Even if the contrast of
It is sufficient that the positive photoresist film 14 remains, and the formation of the opening 13b in the resin layer 13 becomes more reliable. Further, since the opening 13a is always smaller than the designed width of the mask pattern 15a, it is suitable for miniaturization.

This allows for a finer opening 1 compared to the conventional case.
3a becomes easier to form.

Furthermore, as shown in FIGS. 1(c) to (e), the remaining positive photoresist film 14 can be used to form a mask for etching the resin layer 13 and the PSG film 12 in a self-aligned manner. Therefore, the photo process only needs to be done once.
Compared to the conventional method, there is no increase in the number of steps and it takes less time and effort.

In the embodiment, the positive photoresist film 14 is used as the pattern film 14, but a film made of other materials may be used.

〔Effect of the invention〕

As described above, according to the method of manufacturing a semiconductor device of the present invention, the pattern film is left where the opening is to be formed on the planarizing layer, so that the opening can be directly formed as in the conventional method. Compared to the case where a pattern film is formed, it is only necessary that the pattern film remains, and fine openings can be formed more reliably.

Furthermore, when a positive photoresist film is used as the pattern film, in order to leave the positive photoresist film in a region where an opening is to be formed, exposure light must be irradiated to a region other than this region. Therefore, due to the light diffraction phenomenon, the width of the area that is not irradiated with light is always narrowed. Therefore, the width of the opening that is actually formed is always smaller than the designed width of the opening, which is suitable for miniaturization.

This makes it easier to form finer openings than in the conventional case.

Furthermore, the remaining patterned film can be used to form a mask for etching the flattening layer and glabellar insulating film in a self-aligned manner, so only one photo process is required, reducing the number of steps compared to conventional methods. No increase and no hassle.

[Brief explanation of drawings]

FIG. 1 is a sectional view illustrating a method of manufacturing a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a sectional view illustrating a method of manufacturing a conventional semiconductor device. (Explanation of symbols) 1.9...Si substrate, 2.10...5iOz thickness, 3.11...AI wiring, 4...PSG film, 5...resin layer, 6... 5OGII!. 7... Resist film, 7a, 13a, 16a... Opening, 815... Mask, 8a15a... Mask pattern, 12... PSG film (interlayer insulating film), 4a12a... Contact hole, 13...Resin 1! (planarization 1ii), 14...Positive photoresist film (pattern film) 16...SOG
Film (etching-resistant film), 17...Substrate.

Claims (1)

[Claims] A step of forming a pattern film (14) on a planarization layer (13) formed on a substrate (17), and a step of forming a pattern film (14) on a planarization layer (13) formed on a substrate (17);
14) to leave a patterned film (14) where openings in the planarizing layer (13) are to be formed; and applying an etching-resistant material to the entire surface of the planarizing layer (13). forming an etching-resistant film (16) thinner than the pattern film (14) thereon; and selectively removing the remaining pattern film (14) using the etching-resistant film (16) as a mask. Remove and open the opening (1
6a), and selectively removing the planarization layer (13) at the bottom of the opening (16a) using the etching-resistant film (16) as a mask to form an opening (6a) in the planarization layer (13). 16b). 16b).