JPH06275492A - Manufacture of semiconductor device - Google Patents

Abstract

(57) [Summary] [Purpose] The same effect as that of the grazing incidence illumination exposure method for continuous patterns can be exhibited for isolated patterns as well.
It is an object of the present invention to provide a method for manufacturing a semiconductor device which forms an isolated pattern with a resolution almost equal to that of a continuous pattern. [Structure] Auxiliary pattern 1 on both sides of isolated pattern 14
6a and 16b are arranged and the pitch of the blank pattern consisting of the isolated pattern 14 and the auxiliary patterns 16a and 16b is set to L.
& S pattern 12a, 12b, ...
Then, the mask 10 on which the L & S patterns 12a, 12b, ..., The isolated pattern 14 and the auxiliary patterns 16a, 16b are drawn is used to perform exposure by oblique incidence illumination from a four-divided light source. Further, the mask 18 on which the inverted patterns 20a and 20b of the auxiliary patterns 16a and 16b are formed is overlapped and exposed to light, and the transfer pattern by the auxiliary patterns 16a and 16b is erased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device which performs reduction projection exposure by oblique incidence irradiation on a mask on which a fine pattern near the limit resolution of an exposure apparatus is drawn.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of semiconductor devices,
Since it has become difficult to deal with resolution in conventional exposure using circular illumination using a circular light source, the oblique incidence irradiation exposure method in which the shape of the light source of the illumination system is arranged at a pitch that corresponds to the periodicity of the pattern drawn on the mask Is proposed.

As shown in FIG. 3, the radius σ obtained by dividing the light source shape into four by a so-called σ diaphragm is used.
When the light-shielding pattern 32 drawn on the mask 30 is obliquely illuminated using the four-division light source, the incident light passing through both sides of the light-shielding pattern 32 has a phase difference close to π. Since the same effect as the case where the phase shifter is provided on one side is obtained, it is possible to improve the depth of focus and therefore the resolution.

[0004]

However, the effect of the conventional grazing incidence illumination exposure method described above depends on the pitch of the pattern drawn on the mask and the positions of the divided light sources.
It is mainly used for patterns having a certain periodicity. Therefore, a continuous pattern in which patterns of the same shape are repeatedly arranged at a predetermined interval on the same mask and an isolated pattern which is arranged at a predetermined interval or more from adjacent surrounding patterns are mixed. In the case of the mask, even when the oblique incidence illumination exposure method is used, the degree of the effect varies depending on the type of pattern. That is, the depth of focus is improved by the effect of the grazing incidence illumination exposure method for a continuous pattern, but the effect of the grazing incidence illumination exposure method for an isolated pattern is difficult to obtain, and even if the depth of focus is improved, it stops only slightly. .

Therefore, in a mask in which various patterns are mixed, a pattern whose focal depth is improved by the oblique incident illumination exposure method and a pattern in which the focal depth hardly changes are generated, and the focal depth is improved as a whole mask. Therefore, there is a problem that the resolution cannot be improved. There is also a method of separating the continuous pattern and the isolated pattern and using only the isolated pattern as a mask in another layer. However, this method also does not solve the problem that the depth of focus of the isolated pattern is not improved. Therefore, improvement in the resolution as a whole cannot be realized.

Therefore, the present invention allows the isolated pattern to exhibit the same effect as that of the oblique incident illumination exposure method for the continuous pattern, and to form the isolated pattern with a resolution almost equal to that of the continuous pattern. An object is to provide a method for manufacturing a device.

[0007]

SUMMARY OF THE INVENTION The above problem is that a pattern of the same shape is repeatedly arranged on a mask at a predetermined interval and a continuous pattern or an adjacent pattern is arranged at a predetermined interval or more. The isolated pattern is drawn, and auxiliary patterns that are arranged on both sides of the isolated pattern and that form a continuous pattern by combination with the isolated pattern are drawn, and the continuous pattern, the isolated pattern, and the auxiliary pattern are drawn. This is achieved by a method for manufacturing a semiconductor device, which uses the drawn mask to perform reduction projection exposure by oblique incidence illumination from an optimum light source having an optimum light source shape corresponding to the periodicity of the continuous pattern. .

Further, in the above method for manufacturing a semiconductor device, the continuous pattern, the isolated pattern and the auxiliary pattern drawn on the mask are light-shielding patterns, and the portion shielded by the auxiliary pattern is mask-inverted. Reduction projection exposure is performed by forming an inversion mask, and using the mask in which the continuous pattern, the isolated pattern, and the auxiliary pattern are drawn, and the inversion mask by oblique incidence illumination from the optimum light source, respectively. This is achieved by a method of manufacturing a semiconductor device.

Further, the above problem is that a continuous pattern in which patterns of the same shape are repeatedly arranged at a predetermined interval is drawn on the first mask, and the predetermined pattern is drawn from the adjacent pattern on the second mask. While drawing an isolated pattern that is arranged at an interval that is equal to or larger than the interval, and drawing an auxiliary pattern that is arranged on both sides of the isolated pattern and that forms a continuous pattern by combination with the isolated pattern. Oblique incident from an optimum light source having an optimum light source shape corresponding to the periodicity of the continuous pattern, using the first mask in which the continuous pattern is drawn and the second mask in which the isolated pattern and the auxiliary pattern are drawn. This is achieved by a method for manufacturing a semiconductor device, which is characterized in that reduction projection exposure is performed by illumination.

In the method of manufacturing a semiconductor device described above, the isolated pattern and the auxiliary pattern drawn on the second mask are light-shielding patterns, and the portion shielded by the auxiliary pattern is mask-inverted. The first mask is formed and the continuous pattern is drawn.
Manufacturing the semiconductor device, wherein reduced projection exposure is performed by grazing incidence illumination from the optimum light source using the mask, the second mask on which the isolated pattern and the auxiliary pattern are drawn, and the reversal mask, respectively. Achieved by the method.

Further, in the above method of manufacturing a semiconductor device, the pitch of a continuous pattern formed by a combination of the isolated pattern and the auxiliary patterns arranged on both sides of the isolated pattern is substantially equal to the pitch of the continuous pattern. This is achieved by a method of manufacturing a semiconductor device characterized by the above. Further, in the above-described method of manufacturing a semiconductor device, the size of the auxiliary pattern is substantially equal to the size of the isolated pattern.

[0012]

According to the present invention, when a pattern in which a continuous pattern and an isolated pattern are mixed is exposed and transferred, auxiliary patterns are arranged on both sides of the isolated pattern, and a mask in which the continuous pattern, the isolated pattern and the auxiliary pattern are drawn is used. hand,
Since the exposure is performed by the oblique incident illumination from the optimum light source for the continuous pattern, the effect of the oblique incident illumination exposure is exhibited not only for the continuous pattern but also for the isolated pattern and the auxiliary pattern.

Moreover, since the pattern pitch consisting of the isolated pattern and the auxiliary patterns on both sides thereof is substantially equal to the pitch of the continuous pattern, the difference in the effect of oblique incident illumination exposure depending on the pattern type is reduced, and the pattern of the entire mask is reduced. The depth of focus of can be improved to almost the same extent.
Note that it is also possible to separate the first mask on which the continuous pattern is drawn and the second mask on which the isolated pattern and the auxiliary pattern are drawn into masks in different layers and perform exposure to each.

When the isolated pattern, the auxiliary pattern, etc. are light-shielding patterns, the transfer pattern of the auxiliary pattern is formed by overlapping and exposing using a reversing mask in which the portion shielded by the auxiliary pattern is reversed. Since it can be eliminated, there is no need to make any design changes to other mask patterns.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on illustrated embodiments. 1A is a pattern plan view showing a continuous pattern according to one embodiment of the present invention, and FIG.
3A is a pattern plan view showing an isolated pattern and an auxiliary pattern drawn on the same mask as FIG. 3A, FIG. 2 is a pattern plan view showing an inverted pattern of the auxiliary pattern of FIG.
FIG. 3 is a schematic view showing a four-divided light source for oblique incidence illumination used in one embodiment of the present invention.

As shown in FIG. 1A, the mask 10
On the top, the pattern width W1 = 0.3 μm and the pitch P1 =
L & S (line and space) patterns 12a, 12b, ... Remaining 0.6 μm of Cr (chrome) are drawn. On the same mask 10, as shown in FIG. 1B, an isolated pattern 14 having a pattern width W2 = 0.35 μm and remaining Cr is drawn. Then, on both sides of this isolated pattern 14, auxiliary patterns 16a and 16b having a pattern width W3 = 0.35 .mu.m, which is equal to the pattern width W2 of the isolated pattern 14, and having Cr remaining are arranged, and combined with the isolated pattern 14 to form a continuous pattern. The present embodiment is characterized in that

By the way, the L & S patterns 12a, 12
The optimum light source having the optimum light source shape corresponding to the periodicity of b, ... Is a four-divided light source as shown in FIG. That is,
The light source position Pσ (σ
Value) is expressed as Pσ = λ / (2P) where λ is the wavelength of the exposure light P is the pitch of the blank pattern. Therefore, when KrF excimer laser light is used as the exposure light, Pσ = 0.21.

Since the optimum pattern pitch for the four-divided light source is the pitch P = 0.6 μm of the blank pattern, the isolated pattern 14 and the auxiliary patterns 16a and 16a are formed.
By setting the distance d with respect to b from d = 0.25 μm, the pitch of the blank pattern composed of the isolated pattern 14 and the auxiliary patterns 16a and 16b is L & S.
.. equal to the pitch of the patterns 12a, 12b, ...
Match the optimum pattern pitch for the split light source.

In this way, the L & S pattern 12a,
12b, ... And the isolated pattern 14 and the auxiliary patterns 16a and 16b on both sides thereof are punched out with a pitch P = 0.6.
It is formed on the same mask 10 with a thickness of μm. Next, as shown in FIG. 2, a mask 18 in a layer different from the mask 10 is prepared, and auxiliary patterns 16 a and 16 are formed on the mask 18.
Inversion patterns 20a and 20b without Cr in which b is inverted
To form.

Next, using the mask 10, reduction projection exposure is performed by oblique incidence illumination from a four-divided light source, and the L & S patterns 12a, 12b, ..., The isolated patterns 14 and the auxiliary patterns 16a, 16b are used as positive resists on the wafer. Transcribe. Subsequently, reduction projection exposure is similarly performed using the mask 18. Thereby, the auxiliary patterns 16a and 16b
The transfer pattern of is erased. Incidentally, the auxiliary pattern 16
Since the a and 16b and the inverted patterns 20a and 20b have the same size, when the mask 18 is used for exposure, the exposure amount is adjusted so that the transfer patterns of the auxiliary patterns 16a and 16b disappear completely. Please note. Further, instead of adjusting the exposure amount at the time of exposure using the mask 18,
The size of the inverted patterns 20a and 20b is set to the auxiliary pattern 16
It may be slightly larger than a and 16b.

Thereafter, the wafer is developed to form L & S patterns 12a, 12b, ... And isolated patterns 14 made of a positive type resist. As described above, according to this embodiment, the auxiliary patterns 16 are provided on both sides of the isolated pattern 14.
a and 16b are arranged, and the pitch of the blank pattern including the isolated pattern 14 and the auxiliary patterns 16a and 16b is set to L &
By using the mask 10 on which the L & S patterns 12a, 12b, ... When exposed and transferred by oblique incidence illumination from a four-division light source, not only L & S patterns 12a, 12b, ..., But also isolated pattern 14 and auxiliary patterns 16a, 1
Since 6b also exhibits the effect of the oblique incident illumination exposure, the difference in the effect of the oblique incident illumination exposure depending on the type of the pattern can be reduced, and the depth of focus of the pattern of the entire mask 10 can be improved to substantially the same level.

Moreover, the auxiliary pattern 16 on the mask 10
The transfer patterns of a and 16b are auxiliary patterns 16
Since it can be erased by exposing and transferring using the mask 18 on which the inverted patterns 20a and 20b of a and 16b are formed, the L & S patterns 12a,
Only the transfer patterns of 12b, ... And the isolated pattern 14 are formed. Therefore, there is no need to make any design changes to other mask patterns.

Thus, the depths of focus of the L & S patterns 12a, 12b, ... And the isolated patterns 14 mixed on the same mask 10 can be improved to substantially the same level without affecting other mask patterns. Therefore, it is possible to improve the resolution of the pattern of the entire mask 10 to be substantially equal and to improve the stability in pattern formation.

In the above-described embodiment, after exposure is performed using the mask 10 on which the L & S patterns 12a, 12b, ..., The isolated pattern 14 and the auxiliary patterns 16a, 16b are formed, the auxiliary patterns 16a, 16b are reversed. Although the mask 18 of another layer on which the layers 20a and 20b are formed is used to perform the exposure, the exposure may be performed in any order.

Further, it is not necessary to erase the transfer patterns of the auxiliary patterns 16a and 16b arranged on both sides of the isolated pattern 14, and there is no influence on the formation of the semiconductor element even if they are left as they are like an ordinary dummy pattern. In this case, the exposure using the mask 18 can be omitted. When the exposure using the mask 18 can be omitted, it is not necessary to form the L & S patterns 12a, 12b, ..., The isolated pattern 14 and the auxiliary patterns 16a, 16b on the mask 10 by the light-shielding pattern with Cr remaining. , Cr may be used to form the transmission pattern. That is, this case can be applied to the case where either a positive type resist or a negative type resist is used.

Although the L & S patterns 12a, 12b, ..., The isolated pattern 14 and the auxiliary patterns 16a, 16b are formed on the same mask 10 in the above embodiment, the L & S patterns 12a, 12b ,. Mask 10 to isolated pattern 14 and auxiliary pattern 16
You may separate a and 16b. That is, the mask in which the L & S patterns 12a, 12b, ... Shown in FIG. 1A and the mask in which the isolated pattern 14 and the auxiliary patterns 16a, 16b shown in FIG. Even when the exposure and transfer are performed by oblique incidence illumination from the four-divided light source shown in FIG. 2, the same effect as in the case of the above embodiment can be obtained.

In this method, the L & S patterns 12a, 12
b, ... And the auxiliary pattern 1 on both sides of the isolated pattern 14 on the mask 10 on which the isolated pattern 14 is formed.
There is a real benefit when there is not enough space for arranging 6a and 16b. Further, in the above embodiment, the four-divided light source shown in FIG. 2 was used as the light source for performing the grazing incidence illumination exposure, but the present invention is not limited to this four-divided light source, and the L & S pattern 12a, A two-divided light source, an annular light source, or the like may be used depending on the pattern width, pitch, shape, etc. of 12b, ....

[0028]

As described above, according to the present invention, when a pattern in which a continuous pattern and an isolated pattern are mixed is exposed and transferred, auxiliary patterns are arranged on both sides of the isolated pattern, and the continuous pattern, the isolated pattern and the By using a mask on which an auxiliary pattern is drawn and performing exposure with oblique incident illumination from an optimum light source for continuous patterns, the effect of oblique incident illumination exposure is exhibited not only for continuous patterns but also for isolated patterns and auxiliary patterns. It is possible to reduce the difference in the effect of grazing incidence illumination exposure depending on the type, and to improve the depth of focus of the pattern of the entire mask to substantially the same extent.

As a result, the resolution of the pattern of the entire mask can be improved to almost the same level, and the stability in pattern formation can be improved.

[Brief description of drawings]

FIG. 1 is a pattern plan view showing an L & S pattern, an isolated pattern, and an auxiliary pattern, respectively, according to an embodiment of the present invention.

FIG. 2 is a pattern plan view showing an inverted pattern of the auxiliary pattern of FIG.

FIG. 3 is a schematic view showing a four-divided light source for oblique incidence illumination used in an embodiment of the present invention.

FIG. 4 is a schematic diagram for explaining an exposure method by oblique incidence illumination from a conventional four-division light source.

[Explanation of symbols]

 10: Mask 12a, 12b, ...: L & S pattern 14: Isolated pattern 16a, 16b: Auxiliary pattern 18: Mask 20a, 20b: Inversion pattern 30: Mask 32: Light-shielding pattern W1, W2, W3: Pattern width P1, P2: Pitch d: interval between patterns O: lens center Pσ: light source position from lens center O (σ value)

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 7352-4M H01L 21/30 301 C

Claims (6)

[Claims] 1. A continuous pattern in which patterns of the same shape are repeatedly arranged at a predetermined interval and an isolated pattern arranged at an interval of the predetermined interval or more from adjacent patterns are drawn on a mask. , Drawing an auxiliary pattern that is arranged on both sides of the isolated pattern and that forms a continuous pattern by combination with the isolated pattern, using the mask that draws the continuous pattern, the isolated pattern, and the auxiliary pattern, A method of manufacturing a semiconductor device, wherein reduced projection exposure is performed by oblique incidence illumination from an optimum light source having an optimum light source shape corresponding to the periodicity of the continuous pattern. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the continuous pattern, the isolated pattern, and the auxiliary pattern drawn on the mask are light-shielding patterns, and a portion shielded by the auxiliary pattern is masked. Forming an inverted reversal mask and performing reduction projection exposure by oblique incidence illumination from the optimum light source using the continuous pattern, the isolated pattern, the mask on which the auxiliary pattern is drawn, and the reversal mask. A method for manufacturing a characteristic semiconductor device. 3. A continuous pattern, in which patterns of the same shape are repeatedly arranged at a predetermined interval, is drawn on a first mask, and an adjacent pattern is formed on the second mask at a distance equal to or more than the predetermined interval from an adjacent pattern. Drawing an isolated pattern arranged at intervals, drawing an auxiliary pattern arranged on both sides of the isolated pattern and forming a continuous pattern by a combination with the isolated pattern, and drawing the continuous pattern Reduced projection by oblique incidence illumination from an optimal light source having an optimal light source shape corresponding to the periodicity of the continuous pattern, using the first mask and the second mask on which the isolated pattern and the auxiliary pattern are drawn. A method for manufacturing a semiconductor device, which comprises exposing. 4. The method of manufacturing a semiconductor device according to claim 3, wherein the isolated pattern and the auxiliary pattern drawn on the second mask are light-shielding patterns, and a portion shielded by the auxiliary pattern is mask-inverted. And the inversion mask is formed, and the first mask on which the continuous pattern is drawn, the second mask on which the isolated pattern and the auxiliary pattern are drawn, and the inversion mask are respectively used to incline from the optimum light source. A method of manufacturing a semiconductor device, wherein reduced projection exposure is performed by incident illumination. 5. The method for manufacturing a semiconductor device according to claim 1, wherein a pitch of a continuous pattern is a combination of the isolated pattern and the auxiliary patterns arranged on both sides of the isolated pattern. A method for manufacturing a semiconductor device, wherein the pitch is substantially equal to the pitch of the continuous pattern. 6. The method of manufacturing a semiconductor device according to claim 1, wherein a size of the auxiliary pattern is substantially equal to a size of the isolated pattern.