KR100278917B1 - Method for manufacturing contact mask of semiconductor device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a contact mask of a semiconductor device, and utilizes a property that a pattern size in which a line / space exposure mask is decomposable is smaller than that of a contact hole exposure mask. Two exposure masks are used for exposure two times, each exposure energy being less than the energy Ei at which the photoresist film is fully developed, the sum of which is greater than Ei, and the photoresist film is removed by overlapping exposure. Since the photoresist pattern is formed to expose the predetermined part of the hole, the resolution of the contact mask can be improved to form a smaller contact hole safely, which is advantageous for the high integration of the device, and the margin of the contact hole forming process is increased. Process yield is improved.

Description

Method for manufacturing contact mask of semiconductor device

1 is a plan view of an exposure mask for a contact mask of a conventional semiconductor device.

2 is a graph of residual thickness and exposure energy after development of the photosensitive film.

3A and 3B are plan views of exposure masks for a contact mask of a semiconductor device according to an embodiment of the present invention.

4 is a plan view of a semiconductor device exposed using the exposure masks of FIGS. 3A and 3B.

5 is a plan view of a state in which exposure masks for contact masks of a semiconductor device according to another embodiment of the present invention are overlapped.

6 is a plan view of a state in which exposure masks for contact masks of a semiconductor device according to still another embodiment of the present invention are overlapped.

<Description of the symbols for the main parts of the drawings>

1, 1A, 1B: quartz substrate 2, 2A, 2B: light blocking film pattern

3, 3A, 3B: phase inversion film pattern 4, 4A, 4B: exposure area

5A, 5B: Secondary exposure area 6: Semiconductor substrate

7: photosensitive film 10, 10A, 10B: exposure mask

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a contact mask of a semiconductor device. In particular, a line is exposed twice by a predetermined energy using two exposure masks formed so as to overlap a line / space pattern intersecting a portion intended for a contact hole. The present invention relates to a method of manufacturing a contact mask of a semiconductor device capable of forming contact holes having a size / space pattern, which is advantageous for high integration of a device, and increases process margins to improve process yield.

Recently, the trend of high integration of semiconductor devices is greatly influenced by the development of fine pattern formation technology. In particular, the photoresist pattern is widely used as a mask for etching or ion implantation in the semiconductor device manufacturing process.

Therefore, miniaturization of the photoresist pattern is essential for high integration of semiconductor devices, and for this purpose, it is necessary to improve the photo resolution of a stepper, which is a reduced exposure equipment.

In order to improve the optical resolution of the reduced exposure apparatus, the wavelength of the light source is reduced. For example, the G-line and i-line reduced exposure apparatus having wavelengths of 436 and 365 nm have a process resolution of about 0.7 and 0.5 µm, respectively. It is the limit.

Therefore, in order to form a fine pattern of 0.5 μm or less, a reduction exposure apparatus using a deep ultraviolet light, for example, a KrF laser having a wavelength of 248 nm or an ArF laser having a wavelength of 193 nm, may be used as a light source. In the case of a pattern, about 0.30 micrometers of pattern decomposition is also possible.

In addition, the use of a phase shift mask that uses the phase inversion effect of light improves the resolution by about 5 to 10%. Therefore, when the KrF laser reduction exposure device is used, the pattern resolution of about 0.25 μm is used for the line / space pattern. Is possible.

In addition, the contact hole connecting the upper and lower conductive wiring is reduced in size and the distance between the peripheral wiring and the aspect ratio, which is the ratio of the diameter and the depth of the contact hole, is increased. Therefore, in a highly integrated semiconductor device having multiple conductive wirings, accurate and tight alignment between masks in a manufacturing process is required to form a contact, thereby reducing process margin.

The contact hole has misalignment tolerance during mask alignment, lens distortion during exposure process, critical dimention variation during mask fabrication and photolithography process, and between masks to maintain gaps. The mask is formed by considering factors such as registration.

Therefore, in the case of the contact hole, since the resolution is 5 to 10% lower than the line / space pattern, various reduction factors such as the above should be considered. When using a reduction exposure apparatus using a KrF laser and a phase inversion mask, the pattern may be up to about 0.30 μm. Decomposition is possible.

In addition, contact holes with a size less than 0.30㎛ cannot be formed using a reduction exposure device and a phase inversion mask using a KrF laser. For this purpose, contact holes having a size of about 0.25 μm must be formed using an E-beam or X-ray lithography technique. This is possible.

However, such a technique is difficult to apply to the mass production stage because the production amount is significantly smaller than the optical exposure apparatus.

1 is a plan view of an exposure mask for a contact mask of a conventional semiconductor device, and is an example of a phase inversion mask for forming a rectangular contact hole.

First, in the exposure mask 10 for a contact mask, a light blocking film pattern 2 made of a Cr pattern exposing a rectangular exposure area 4 corresponding to a contact hole at a predetermined interval is formed on a quartz substrate 1. In addition, a phase inversion film pattern 3 is formed on four sides of the contact hole exposure area 4 in the longitudinal direction to prevent image contrast reduction due to diffraction of the contact hole exposure area 4.

The conventional method for manufacturing a contact mask of a semiconductor device as described above uses a phase inversion mask in which a phase inversion film pattern is formed around an exposure mask corresponding to a contact hole. It is possible to manufacture contact holes up to a degree, and it is difficult to form patterns below that, so that there is a problem that high integration of the device is difficult to some extent.

The present invention has been made to solve the above problems, and an object of the present invention is to perform two exposures using two phase reversal masks in which lines / spaces are formed to cross each other, which is smaller than that of a contact hole exposure mask. The present invention provides a method for manufacturing a contact mask of a semiconductor device, which is advantageous in increasing integration of a device by reducing the size of a contact hole rather than using a contact mask.

A feature of the method for manufacturing a contact mask of a semiconductor device according to the present invention for achieving the above object and object is a process of forming a photoresist film on a semiconductor substrate, the line / spacer pattern is formed in the photoresist film is a contact hole A first exposure process of exposing only a portion of the photosensitive energy of the photosensitive film using a first phase inversion mask having a portion located in a space, and a line / space pattern intersecting with the line / space pattern of the first phase inversion mask is formed A second exposure process using a second phase inversion mask that exposes portions intended to be contact holes overlapping with the remaining energy necessary for the photosensitive film to be exposed; and developing the exposed photoresist film to remove portions intended to be contact holes. It is provided with the process of forming the photosensitive film pattern.

Hereinafter, a method of manufacturing a contact mask of a semiconductor device according to the present invention will be described in detail with reference to the accompanying drawings.

3A and 3B are plan views of exposure masks for contact masks of a semiconductor device according to an embodiment of the present invention, in which contact holes are arranged in a matrix shape.

4 is a plan view of a semiconductor device exposed using the exposure masks of FIGS. 3A and 3B, and will be described in relation to each other.

First, a positive photosensitive film 7 having a non-exposed area as a pattern is coated on the semiconductor substrate 6, and then exposed to a predetermined exposure energy using the first exposure mask 10A to expose the first exposure area 4A. To form. At this time, the first exposure mask 10A has a light blocking film pattern 2A having a line / space in the vertical direction formed on the quartz substrate 1A, and the size of the X-hole of the contact hole to be formed is This is a Levenson type phase inversion mask in which the phase inversion film pattern 3A is formed on every other space.

In addition, as shown in FIG. 2, the primary exposure energy starts to develop from a threshold energy (hereinafter referred to as Eth) during development, and is completely removed above an arbitrary energy (hereinafter referred to as Ei). It exposes by energy below Ei using the property to become.

The photoresist film 7 is then subjected to secondary exposure with a predetermined energy using a second exposure mask 10B to form a second exposure area 4B that overlaps the first exposure area 4A.

At this time, the second exposure mask 10B has a light blocking film pattern 2B having a line / space in a horizontal direction on the quartz substrate 1B, and the size of the Y-axis of the contact hole to be formed is This is a Levenson type phase inversion mask in which phase inversion film patterns 3B are formed on every other space.

In addition, the secondary exposure energy is exposed so that the sum of the primary exposure energy is equal to or greater than Ei.

Thus, as shown in FIG. 4, the first and second exposure areas 4A arranged once in a matrix shape, where the photoresist film 7 is not sufficiently removed or not removed at all in the once exposed or non-exposed areas. ) And (4B), the photosensitive film 7 is completely removed to become a contact hole mask.

The portion where the first and second exposure areas 4A and 4B overlap is 1 in the first and second exposure masks 10A and 10B, respectively. Open area of the light shielding pattern 2A-Open area of the light shielding pattern 2B, 2). Open area of light-blocking film pattern (2A) -Open area of phase inversion film pattern (3B), 3). The open area of the phase inversion film pattern 3A-the open area of the phase inversion film pattern 3B.

5 is a plan view of a state in which exposure masks for contact masks of a semiconductor device according to another exemplary embodiment of the present invention are overlapped.

In particular, the first and second exposure masks 10A and 10B having short horizontal and vertical lines / spaces may be sequentially exposed twice in order to increase the resolution improvement due to the phase inversion effect. The sum of the exposure energies is equal to or greater than Ei.

In this case, the first and second exposure masks 10A and 10B are light blocking film patterns 2A having short lengths of horizontal and vertical lines / spaces on two quartz substrates 1A and 1B, respectively. And (2B) are formed, and the light blocking film patterns 2A and 2B cross each other at right angles.

In addition, the first and second exposure masks 10A and 10B are formed in each of the light blocking layer patterns 2A and 2B, which are repeatedly formed in respective spaces, and the open area and the phase inversion pattern 3A and 3B. Are formed to overlap each other, and separate auxiliary exposure regions 5A and 5B are formed at one side of each space to increase the phase inversion effect.

Therefore, overlapping portions of the light blocking film patterns 2A and 2B open areas of the first and second exposure masks 10A and 10B overlap the open areas of the phase shift film patterns 3A and 3B. It becomes a contact hole by.

FIG. 6 is a plan view of a state in which exposure masks for contact masks of a semiconductor device overlap with each other according to another exemplary embodiment of the present invention, and an example in which contact holes are irregularly arranged like a LOSIC device.

Two exposures are sequentially performed using the first and second exposure masks 10A and 10B having short lengths and irregularly arranged horizontal and vertical lines / spaces, and the sum of the respective exposure energies is equal to or greater than Ei. To be.

In this case, the first and second exposure masks 10A and 10B are formed on the quartz substrates 1A and 1B, respectively, in the horizontal and vertical lines / spaces that cross each other in cross shape at short and irregular positions. Light blocking film patterns 2A and 2B are formed, and a phase inversion film pattern 3A is formed in the open region of the light blocking film pattern 2A of the first exposure mask 10A.

In the first and second exposure masks 10A and 10B, the phase inversion film pattern 3A and the light blocking film pattern 2B open area overlap each other, and the periphery of the open area of the light blocking film pattern 2B is overlapped. Auxiliary exposure areas 5B for the phase inversion effect are formed on the substrate.

Therefore, a portion where the phase inversion film pattern 3A of the first and second exposure masks 10A and 10B overlap the open area of the light blocking film pattern 2B becomes a contact hole by overlapping exposure.

As described above, the method of manufacturing a contact mask of a semiconductor device according to the present invention utilizes a property that the pattern size of the line / space exposure mask is smaller than that of the contact hole exposure mask, so that the lines intersect at the contact hole positions. Two exposure masks are used using two exposure masks having a / space pattern, and each of the two exposure energies is less than the energy Ei at which the photoresist film is fully developed, and the sum is greater than Ei to expose the overlapped portion of the photoresist film. Since the photoresist pattern is formed by exposing the predetermined portion to the contact hole, the resolution of the contact mask is improved to form a smaller contact hole safely, which is advantageous for the high integration of the device and allows for the formation of the contact hole. The degree is increased, there is an advantage that the process yield is improved.

Claims (5)

Forming a photoresist film on a semiconductor substrate, and exposing the photoresist film with only a part of the photosensitive energy of the photoresist film by using a first exposure mask having a line / space pattern formed thereon and having a space located in a portion intended as a contact hole. A first exposure process and a line / space pattern that intersects the line / space pattern of the first exposure mask are formed, and a second exposure mask that overlaps a portion of the photosensitive film, which is intended to be a contact hole, is used. A method of manufacturing a contact mask for a semiconductor device, comprising: a second exposure step of exposing with remaining energy necessary for photosensitivity; and a step of developing the exposed photoresist to form a photoresist pattern in which portions intended to be contact holes are removed. The method of claim 1, wherein the portions of the photosensitive film pattern to be removed are arranged in a shape of a mat-lips. The method of claim 1, wherein portions of the photosensitive film pattern to be removed are irregularly arranged. 2. The method of claim 1, wherein the first and second exposure masks are phase inversion masks. The contact of the semiconductor device according to claim 4, wherein a separate auxiliary exposure area in which the light blocking film pattern is removed to a predetermined width is formed on one side of the space of the first and second exposure masks to increase the phase inversion effect. Mask manufacturing method.