JPH09213609A - Method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expose a specific pattern shape faithfully to a resist film by a method wherein a designed pattern shape is divided into at least two reticles to be successively exposed using the divided respective reticles. SOLUTION: A substrate 1 is coated with a resist film 3 about 1μm thick (a). Next, a reticle 4 in striped X directional line pattern is held between the resist film 3 and a lamp 6 to be exposed by the lamp 6 in about half thickness from the surface of the resist film 3 (b). Next, the reticle 4 is substituted for another reticle 5 of the Y directional line pattern to be exposed in about half thickness from he surface of the resist film 3 (c). Next, when the regions exposed from both of the reticles 4 and 5 reaching the surface of an insulating film to imnerse the resist film 3 in a developer, a square contact hole pattern shaped resist film 3 is formed (d). Through these procedures, the scattering of exposed light flux caused in an angle pattern shape of the reticles can be avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic technique used when forming an integrated circuit of a semiconductor device, and more particularly to improving pattern formation of a resist film.

[0002]

2. Description of the Related Art Generally, when forming a wiring pattern of an integrated circuit of a semiconductor device, for example, after forming an element on a substrate such as a semiconductor substrate, an insulating layer is formed on the area of the element, and then the insulating layer is formed. A wiring layer made of a conductor such as aluminum is formed on or around the layer. Then, a resist film is applied onto the wiring layer by spin coating or the like, and is formed as a mask by a photo-forming technique. Using this mask, the wiring layer is etched to form a wiring pattern by using a lithography technique. There is.

When forming this wiring pattern, since the wiring layer is usually formed with the element region via an insulating layer, a contact hole is formed for connection with the element region.

[0004]

In the conventional lithographic technique described above, for example, as shown in FIG. 3A, a SiO ₂ film having a film thickness of 500 nm deposited on a semiconductor substrate 21 made of silicon. 22 is formed, where
Consider the case where a 0.5 μm × 0.5 μm contact hole is opened.

In the conventional photolithography technique, as shown in FIG.
A reticle in which a contact hole pattern 25 for forming the contact hole is drawn between a resist film 23 containing a photosensitizer and having a thickness of about 1 μm and a lamp 26 serving as a light source for exposure as shown in (b). Sandwich 24.

Next, the lamp 26 is turned on for a certain period of time, for example,
When the light is turned on for 600 msec, the light flux passes through the unshielded contact hole pattern 25 of the reticle 24 and exposes the resist film 23. Then, the sufficiently exposed resist film 23 is dipped in a developing solution to remove unnecessary portions, and a resist film 23 having a contact hole pattern 27 as shown in FIG. 3C is formed.

However, the contact hole pattern 27 formed as shown in FIG.
It is not a 5um x 0.5um square contact hole. This is because the light flux is scattered at the four corners of the contact hole pattern 25 during exposure, and the pattern shape drawn by the reticle 24 is not faithfully transferred to the resist film 23. Is rounded and the pattern collapses.

Therefore, even if a rectangular contact hole pattern is formed on the reticle, the resist film is exposed to a contact hole with rounded corners or a circular shape. The corners are only circular.

Not only the contact holes but also the intersections of the wirings are similarly exposed to have a rounded shape with rounded corners. In particular, the finer the pattern, the more the pattern shape collapses.

The inability to form a pattern as designed in this manner is a fatal problem from the viewpoint of manufacturing integrated circuits, and a drastic solution is required. Therefore, the present invention provides a method for manufacturing a semiconductor device in which exposure of a mask pattern onto a resist film is exposed by a plurality of reticles obtained by dividing one mask pattern to form a resist pattern having a desired design. To aim.

[0011]

In order to achieve the above object, the present invention uses a plurality of n reticles obtained by dividing a pattern shape of one resist mask into a plurality of patterns in a lithography technique used for manufacturing a semiconductor device. hand,
Using each reticle as a mask, each exposure is performed once to reach a depth of 1 / n in the depth direction of the resist film to be the resist mask, and the exposure is performed over the entire reticle to the bottom of the resist film. After that, a development method is provided to provide a method for manufacturing a semiconductor device in which the pattern shape of the resist mask is formed.

In the method of manufacturing a semiconductor device having the above-described structure, when the resist film is patterned by the lithography technique, the designed pattern shape is set to 2
The reticle is divided into one or more sheets, and the divided reticle is used to sequentially expose the reticle so that the desired pattern shape is faithfully exposed to the resist film.

[0013]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. 1 (a) to 1 (d)
A process example of the method of manufacturing the semiconductor device according to the first embodiment of the present invention will be described below. Here, in this embodiment, a positive type resist is used as the resist film.

In FIG. 1A, a silicon oxide (SiO ₂ ) film 2 having a thickness of 500 nm is deposited on a silicon semiconductor substrate 1 by using a CVD apparatus or the like, and further 0.5 μm ×
The case where a contact hole of 0.5 μm is opened is taken as an example.

In the photolithography technique, first, a resist film 3 containing a photosensitizer and having a thickness of about 1 μm is applied by spin coating or the like. Subsequently, as shown in FIG. 1B, a reticle 4 having a stripe-shaped X-direction line pattern is sandwiched between the resist film 3 and the lamp 6 serving as a light source. afterwards,
The lamp 6 is turned on to expose the resist film 3. In this case, as shown in FIG. 1B, the resist film 3 of 1 μm is exposed to a depth of 0.5 μm from the surface.
That is, the exposure amount of the lamp 6 is reduced to half the original exposure amount.

Subsequently, the reticle 4 having the X-direction line pattern is replaced with the reticle 5 having the Y-direction line pattern,
As shown in FIG. 1C, the resist film 3 is exposed to a depth of 0.5 μm from the surface. Then, the regions exposed by both the reticle 4 having the X-direction line pattern and the reticle 5 having the Y-direction line pattern are sufficiently exposed to reach the surface of the insulating film. This area is an area to be an opening of a mask for forming a contact hole.

Next, when the exposed resist film 3 is dipped in a developing solution, the exposed resist portion is removed.
The resist film 3 having the square contact hole pattern shape shown in (d) can be formed.

Next, a second embodiment in which a square resist mask as shown in FIGS. 2A to 2C is formed in a convex shape will be described. Here, in this embodiment, a positive type resist is used as the resist film.

Similar to the first embodiment described above, a 500 nm film is formed on the silicon semiconductor substrate 11 by a CVD device or the like.
The SiO ₂ film 12 is formed to a film thickness of. Further, a resist film 13 containing a photosensitizer and having a thickness of about 1 u is applied. Next, X is provided between the resist film 13 and the lamp 16 which serves as a light source.
The reticle 14 having the direction line pattern is sandwiched. Here, the reticle 14, 15 has a light-shielding portion inverted from that of the reticle 4, 5 used in the above-described first embodiment.

Then, the lamp 16 is turned on and the lamp shown in FIG.
As shown in (b), the resist film 13 is sufficiently exposed. Next, the reticle 14 is replaced with a reticle 15 having a Y-direction line pattern as shown in FIG. 2C, and similarly sufficiently exposed. Then, the exposed semiconductor substrate 11 is dipped in a developing solution to remove the exposed portion.
It is possible to form a resist mask 17 having a square convex pattern shape as shown in (d).

As described above, according to the method for manufacturing a semiconductor device of the present invention, a plurality of reticles are created by dividing a designed complicated pattern shape into simple pattern shapes having no corners. . The reticle is used to sequentially expose the resist film halfway, and the last reticle is used to expose the bottom of the resist film.
By such a manufacturing process, even if the mask pattern shape is complicatedly designed, it is divided into simple patterns that do not have corners, and a complicated pattern at the time of design is configured by exposing multiple times. As described above, it is possible to prevent collapse of the resist pattern due to light scattering at the corners of the reticle pattern.

In the first and second embodiments described above,
I used a positive type resist for the resist film,
The same effect can be obtained by using a negative type resist. However, the light blocking portion of the reticle is inverted.

Further, in the exposure by the lamps 6 and 16 described above, the adjustment of the thickness of the resist film exposed to the middle of one reticle may be performed by reducing the light amount of the lamp or by changing the irradiation time of the lamp. You may reduce and adjust. The amount of light and the irradiation time may be set empirically thereafter by previously obtaining data using a test pattern or the like. Further, these data may be stored in a memory or the like provided in the exposure apparatus, and the light amount and irradiation time may be automatically set by inputting the thickness of the resist film and the number of reticles.

Further, the thinnest part of the resist film that finally remains after exposure by a plurality of exposures must have a thickness that can withstand the etching process until a target part to be etched such as a contact hole is formed.

[0025]

As described above in detail, according to the method of manufacturing a semiconductor device of the present invention, a plurality of reticles having a simple pattern in which the pattern shape of one intricately designed resist mask does not have a rectangular shape (rectangle). By dividing into two and exposing each, it is possible to prevent the scattering of the light flux for exposure that occurs in the angular pattern shape of the reticle at the time of exposure, prevent the resist pattern from collapsing, and form the resist pattern shape as desired be able to.

Further, a method of manufacturing a semiconductor device according to the present invention
It is effective not only for contact holes but also for portions where wiring lines intersect or bend at corners, and is suitable for forming a fine pattern.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a step of a method for manufacturing a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a process example of a method of manufacturing a semiconductor device according to a second embodiment of the present invention.

FIG. 3 is a diagram for explaining a conventional method for manufacturing a semiconductor device by a lithography technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Silicon semiconductor substrate 2 ... Silicon oxide film (SiO ₂ ) 3 ... Resist film 4 ... X-direction light pattern reticle 5 ... Y-direction light pattern reticle 6 ... Lamp

Claims (10)

[Claims] 1. In a lithography technique used for manufacturing a semiconductor device, a plurality of n reticles obtained by dividing a pattern shape of one resist mask into a plurality of patterns are used, and each reticle is used as a mask to perform one exposure. Exposure is performed to reach a depth of 1 / n in the depth direction of the resist film to be the resist mask, and after exposure to the bottom of the resist film by exposure over the entire reticle, development processing is performed to form the pattern shape of the resist mask. A method of manufacturing a semiconductor device, comprising: 2. The method of manufacturing a semiconductor device according to claim 1, wherein a positive type resist is used for the resist film, and the exposed portion is removed by the developing process. 3. The method of manufacturing a semiconductor device according to claim 1, wherein a negative type resist is used for the resist film, and an unexposed portion is removed by the developing process. 4. The reticle divides the pattern shape of one resist mask into a plurality of n patterns, each of which does not include a prism, and when the reticle exposes a resist film, an exposure caused by the prism is formed. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the scattering of the use light beam is suppressed. 5. The pattern shape of the resist mask is
The method of manufacturing a semiconductor device according to claim 1, wherein the pattern is a pattern including a contact hole that connects layers. 6. The pattern shape of the resist mask is
2. The method of manufacturing a semiconductor device according to claim 1, wherein the wiring pattern is a wiring pattern including intersecting portions and portions that bend at corners. 7. The manufacturing of a semiconductor device according to claim 1, wherein the adjustment in the depth direction of the resist film serving as the resist mask by one exposure is based on the adjustment of the light amount of the light source for exposure. Method. 8. The semiconductor device according to claim 1, wherein the adjustment of the depth direction of the resist film serving as the resist mask in one exposure is based on adjustment of irradiation time of a light source for exposure. Production method. 9. The thinnest part of the resist film formed by exposing and developing to the bottom of the resist film by exposure over the entire reticle has a thickness that can withstand etching until a part to be etched is formed. The method for manufacturing a semiconductor device according to claim 1, wherein there is. 10. A lithographic technique used for manufacturing a semiconductor device, wherein a resist film formed on a substrate is formed by using a plurality of n reticles in which a pattern shape of one resist mask is divided into a plurality of patterns each not including a polygon. Exposing the resist film to the middle of the film thickness using the first reticle as a mask, and replacing the resist film up to the nth reticle, and exposing repeatedly the last reticle to expose the bottom of the resist film. And the step of developing the resist film of the exposed substrate to form the pattern shape of the mask, eliminating the square shape from the pattern drawn on each reticle, and exposing the square shape A method for manufacturing a semiconductor device, which suppresses scattering of a light flux.