JP2998661B2 - Photomask and pattern forming method for semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask used in a manufacturing process of a semiconductor device, and more particularly to a method of forming a pattern of a semiconductor device. The present invention relates to an expandable photomask and a method for forming a pattern of a semiconductor device.

[0002]

2. Description of the Related Art Heretofore, photomasks having various pattern shapes have been used, and fine light-transmitting portions and light-shielding portions are repeatedly formed in a pattern to be continuously arranged on a plane. . In this photomask, if the shape of the light shielding portion is substantially the same in the vertical direction (Y-axis direction) and in the horizontal direction (X-axis direction), With respect to resolution or light intensity, there was almost no difference in directionality, and no practical problem occurred. However, as shown in FIG. 3, the length in the vertical direction (Y-axis direction) and the width in the horizontal direction (X
When a photomask having a light-shielding portion having a different length (axial direction) is used, there is a problem that defocus occurs and a pattern between adjacent electrodes is easily connected at the time of defocusing.

[0003]

That is, one example of a conventional photomask is shown in FIG. This pattern is used to form an electrode of a dynamic memory of a semiconductor device, and is configured such that the length in the vertical direction (Y-axis direction) is longer than the length in the horizontal direction (X-axis direction). This is a rectangular array pattern, and the light-shielding region 1 is an electrode portion, and the light-transmitting portion, that is, the light-transmitting region 3 is a portion between electrodes.

As an example of the dimensions of each pattern in such a photomask, the dimensions of the electrodes in the vertical direction (Y-axis direction) are as follows.
The dimension between the electrodes was 1.62 μm, the dimension between the electrodes was 0.252 μm, and the dimension of the electrodes in the lateral direction (X-axis direction) was 0.32 μm.
756 μm, and the dimension between the electrodes is 0.252 μm. Through the photomask, the photoresist on the semiconductor substrate is exposed using, for example, a 縮小 reduction projection type exposure apparatus.

The amount of exposure at this time is set so that the dimension between the electrodes in the horizontal direction is equal to the dimension between the electrodes in the horizontal direction of the photomask. Thereafter, an etching process is performed in an etching process using the resist pattern as a mask, and a predetermined pattern is formed. However, in a photomask composed of a light-shielding portion having such a shape, at the time of exposure,
When the resist is irradiated using the photomask, the resist is irradiated in the horizontal direction (X-axis direction), that is, AA ′ shown in FIG.
The light intensity distribution in the cross section and the light intensity distribution in the vertical direction (Y-axis direction), that is, the light intensity distribution in the BB ′ cross section shown in FIG. 9 may be different, and a desired accurate pattern may not be formed. It was found to happen.

This phenomenon occurs when a light beam passing between the light shielding portions of the photomask is diffracted in a lateral direction (X-axis direction).
It is considered that the diffraction conditions are different from each other in the vertical direction (Y-axis direction). In the photomask, the light intensity distribution on the wafer from 0 to 0.9 μm in defocus between the electrodes in the horizontal cross section AA ′ and the vertical cross section BB ′ of the electrode is shown. As shown in FIG.

The X and Y coordinates of this light intensity distribution are coordinates when the center between the electrodes is set to 0, and the value when the values of X and Y are doubled is the dimension between the electrodes. Generally, in the light intensity distribution of FIG. 9, there are places where the light intensity does not change when defocusing occurs. Such places are generally referred to as pivot points. In the cross section in the AA 'direction (lateral direction), the dimension of the pivot point is X =
It is 0.19 μm.

[0008] The dimensions of the pivot point are AA '.
X = 0.1 which is the patterning dimension of the portion between the electrodes in the direction
26 μm is significantly different. B-
In the inter-electrode portion in the B ′ direction (vertical direction), the dimension of the pivot point is Y = 0.13 μm, and X = the patterning dimension of the inter-electrode portion in the BB ′ direction (vertical direction).
It is almost equal to 0.126 μm.

This is because the vertical pitch of the electrodes is 1.87.
2 μmL / S, horizontal pitch is 1.008 μm
This is because L / S and the pitches in the vertical direction and the horizontal direction are largely different, so that the behavior of the light intensity distribution when defocused is different from each other. X = 0.126μ where the dimension between the electrodes in the horizontal direction is the same as the photomask dimension
FIG. 6 shows a distribution of the light intensity I at the time of m on a plane from 0 to 0.9 μm in defocus at I = 0.28.

As can be understood from FIG. 6, since the dimension of the pivot point and the patterning dimension are almost equal in the portion between the electrodes in the direction of BB ', the amount of dimensional change upon defocusing is small. Since the patterning dimension of the inter-electrode portion in the 'direction' and the pivot point are greatly different, the amount of dimensional change at the time of defocus increases, especially when the defocus reaches 0.9 μm, the connection between the electrodes in the AA 'direction is There was a problem that it became easier.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the conventional problems and to reduce the amount of change in size even when defocusing by increasing the patterning dimension and the dimension of the pivotal point, thereby increasing the focus margin. And a method for forming a pattern of a semiconductor device.

[0012]

The present invention basically employs the following technical configuration in order to achieve the above object. That is, as a first aspect of the present invention, a rectangular length different from the vertical length and the horizontal length is used.
The light-shielding part of the shape has a predetermined interval in the vertical and horizontal directions
Placed in a photo mask that is configured to be arranged with the
Te, the light-shielding portion, to separate the longitudinal direction of the light shielding portion
Thus, a photomask provided with a slit portion having a width not to be resolved on the resist , and a second aspect of the present invention is to apply a resist to a semiconductor substrate.
The application process differs from the vertical and horizontal lengths
Rectangular light-shielding parts are defined in the vertical and horizontal directions, respectively.
Patterns that are arranged with intervals
Exposing the resist through a photomask containing
And a step of performing development after the exposure processing.
In the method of forming a pattern of a conductor device, the photomac
So that the longitudinal direction of the light-shielding portion is separated
Slits with a fine width that does not allow resolution
Te, Ru Oh <br/> pattern formation method of a semiconductor device exposure.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The photomask and the method for forming a pattern of a semiconductor device according to the present invention employ the above-mentioned technical constitution, and particularly, photomasks having different lengths in the vertical and horizontal directions. By inserting a slit having a width that does not resolve the pattern on the wafer into the light-shielding part of the pattern constituting the reticle,
By moving the dimension of the pivot point to the vicinity of the patterning dimension, the amount of dimensional change at the time of defocus is reduced, and the focus margin is increased.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a photomask and a method for forming a pattern of a semiconductor device according to the present invention. FIG. 1 is a diagram showing an example of the configuration of a specific example of a photomask according to the present invention. In the figure, a photomask 4 in which light-transmitting portions 3 and light-shielding portions 1 are alternately arranged is shown. 1 shows a photomask 4 in which a light-shielding portion 1 is provided with a slit portion 2 crossing the light-shielding portion 1.

That is, the photomask 4 according to the first embodiment of the present invention shown in FIG. 1 has a large number of fine light transmitting portions 3 and light shielding portions 1 formed on a reticle in both the vertical and horizontal directions. The light-shielding portion 1 has a pattern shape formed in an array. In particular, as shown in FIG.
However, the present invention is particularly effective for those having shapes in which the lengths in two orthogonal directions are different from each other.

That is, as the pattern of the photomask 4 according to the present invention, it is desirable that the light shielding portion 1 is rectangular. Further, it is desirable that the slit portion 2 provided in the light shielding portion 1 according to the present invention is formed so as to cross the light shielding portion 1 as shown in the figure. Further, in the present invention,
For example, the width of the slit portion 2 needs to have a small slit width such that the slit portion is not resolved on the resist during exposure.

The slit portion 2 used in the present invention may be arranged only one in the horizontal direction in the one light shielding portion 1 as shown in FIG. As shown in FIG. 1, a plurality of slits 2 and 2 ′ may be arranged in one light-shielding portion 1 in a lateral direction and parallel to each other. Further, in the present invention, as shown in FIG. 1 or FIG. 2, one or a plurality of slits 2 may be formed not only in the horizontal direction but also in the vertical direction.

Further, in the present invention, it is possible to mix vertical and horizontal slits in one light shielding portion 1. According to a second aspect of the present invention, there is provided a pattern forming method for a semiconductor device, comprising: a step of applying a resist to a semiconductor substrate; a step of exposing the resist through a photomask; and a step of performing development after the exposure processing. In a pattern forming method of a semiconductor device in which a light-shielding portion for forming a repetitive pattern on the photomask is provided with a fine slit so as not to be resolved at the time of exposure and exposure processing is performed, particularly, the special photomask described above is used. It is characterized by using and performing exposure processing.

Next, a first specific example according to the present invention is shown in FIG.
This will be described in detail with reference to FIGS. That is, the photomask 4 according to the present invention shown in FIG. 1 has a reticle chrome having a rectangular shape as shown in FIG. Two 0.1 μm slit portions 2 are inserted in the pattern portion on the wafer in the horizontal direction.

In this specific example, the dimension of the vertical electrodes is 1.62 μm, the dimension between the electrodes is 0.252 μm, and the dimension of the horizontal electrodes is 0.756 μm, and the dimension between the electrodes is It was 0.252 μm. Using this photomask, exposure processing was performed on the photoresist on the semiconductor substrate by a 1/5 reduction projection type exposure apparatus, followed by development processing to form a resist pattern.

The optical conditions at this time are: λ = 365 nm,
NA = 0.57 and σ = 0.7, and the amount of exposure was such that the dimension between the electrodes in the horizontal direction was equal to the size of the photomask.
In the development process, paddle development was performed for 60 seconds with a 2.38% aqueous solution of TMAH as in the past. In the photomask obtained according to the first embodiment of the present invention, light having a defocus of 0 to 0.9 .mu.m between the electrodes in the horizontal section AA 'and the vertical section BB' is used. FIG. 7 shows the intensity distribution.

As described above, the coordinates of X and Y in the light intensity distribution are the coordinates when the center between the electrodes is set to 0, and the value when the values of X and Y are doubled is the value between the electrodes. The dimensions are as follows. Compared with the conventional photomask of FIG. 3 in which no slit is inserted, the dimension which becomes the pivot point in the AA ′ direction is X = 0.16 μm, and a slit pattern that is not resolved on the wafer of the present invention is inserted. Thereby, the patterning dimension X approaches 0.126 μm.

The distribution on a plane from defocus 0 to 1.2 μm at a light intensity I = 0.29 when X = 0.126 μm, where the dimension between the electrodes in the horizontal direction is equal to the photomask dimension. It is shown in FIG. FIG. 4 is compared with the distribution seen in a plane in the prior art shown in FIG. 6, and in the prior art, when the defocus is 0.9 μm, the patterns are connected in the AA ′ direction. On the other hand, in the reticle of this specific example according to the present invention, the drawback that the patterns are connected at the same defocus amount does not occur, and the defocus amount becomes 1.2 μm, and It can be seen that pattern connection has occurred.

From the above results, by using the photomask of the present invention, it is possible to obtain a relatively strong light intensity as compared with the conventional method even when defocusing, and at the same time, to reduce the size. It can be seen that the change amount is small and the focus margin is expanded. Further, a second specific example according to the present invention will be described in detail with reference to FIG. 2, FIG. 5, and FIG.

That is, the photomask 4 according to the present invention shown in FIG. 2 has a rectangular light shielding portion 1 as shown in FIG. 3, which is a conventional photomask pattern, and a chrome pattern portion of a reticle on the wafer. A single 1 μm slit portion 2 is inserted in the horizontal direction. Further, the dimension between the electrodes in the vertical and horizontal directions of the photomask 4 in this specific example is the same as that of the conventional example.

The subsequent steps were the same as in the first embodiment. In the photomask obtained according to the second embodiment of the present invention, the defocus between the electrodes in the cross-sectional direction AA ′ and the cross-sectional direction BB ′ in the horizontal direction is 0 to 0.75 μm.
FIG. 8 shows the light intensity distribution up to this point. As described above, the coordinates of X and Y of the light intensity distribution are coordinates when the center between the electrodes is set to 0, and the value when the values of X and Y are doubled is the dimension between the electrodes. Become.

Similar to the first specific example, when compared with the conventional photomask of FIG.
The dimension of the pivot point in the AA 'direction is X = 0.
By inserting a slit pattern that is not resolved on the wafer of the present invention, the patterning dimension X becomes closer to 0.126 μm. FIG. 5 shows the distribution on a plane up to X = 0.126 μm where the horizontal inter-electrode dimension is equal to the photomask dimension.

When FIG. 5 is compared with the distribution of the prior art shown in FIG. 6 in a plane view, in the prior art, patterns are connected in the AA 'direction at a defocus of 0.9 μm. On the other hand, in the reticle of this example according to the present invention, the drawback that the patterns are connected at the same defocus amount does not occur, and the defocus amount is 1.2 μm.
m, it can be seen that pattern connection in the AA ′ direction has occurred.

From these results, by using the photomask of the present invention, it is possible to obtain a relatively strong light intensity as compared with the conventional method even when defocusing, and at the same time, it is possible to reduce the size. It can be seen that the change amount is small and the focus margin is expanded.

[0030]

In the method for forming a pattern of a photomask and a semiconductor device according to the present invention, when a photomask pattern on a reticle having light-shielding portions having different lengths in a vertical direction and a horizontal direction is used. By inserting a fine slit portion that does not allow the pattern to be resolved on the wafer, the dimension of the resolution point when defocused is reduced by moving the dimension of the pivotal point to near the patterning dimension. It is possible to do
Further, the effect of increasing the focus margin can be obtained.

[Brief description of the drawings]

FIG. 1 is a reticle pattern diagram showing a configuration of a specific example of a photomask according to the present invention.

FIG. 2 is a reticle pattern diagram showing a configuration of another specific example of the photomask according to the present invention.

FIG. 3 is a reticle pattern diagram showing a configuration of an example of a conventional photomask.

FIG. 4 is a view illustrating defocuses 0 to 0 obtained by a fine pattern forming method according to a first embodiment of the present invention;
FIG. 4 is a light intensity distribution diagram of a plane up to 1.2 μm.

FIG. 5 is a view showing defocuses 0 to 0 obtained by a fine pattern forming method according to a second embodiment of the present invention;
FIG. 4 is a light intensity distribution diagram of a plane up to 1.2 μm.

FIG. 6 is a light intensity distribution diagram of a plane from defocus to 0 to 0.9 μm obtained by a conventional fine pattern forming method.

FIG. 7 is a light intensity distribution chart on a resist from 0 to 0.9 μm in defocus obtained by the first embodiment of the present invention.

FIG. 8 is a light intensity distribution chart on a resist from 0 to 0.9 μm in defocus obtained by the second embodiment of the present invention.

FIG. 9 is a light intensity distribution chart on a resist from 0 to 0.9 μm in defocus obtained by a conventional semiconductor device pattern formation method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Light shielding part 2: Slit part 3 ... Light shielding part 4: Photomask

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03F 1/08 H01L 21/027

Claims (6)

(57) [Claims] 1. A vertical length is different from a horizontal length.
A rectangular light-shielding part is provided between the vertical and horizontal directions
All the photo mask that is configured to be arranged with the interval
There are, on the light-shielding portion, to separate the longitudinal direction of the light shielding portion
A photomask provided with a slit portion having a width not to be resolved on a resist . 2. The method according to claim 1, wherein the slit portion is provided within the light shielding portion.
It is noted that one or a plurality of
The photomask according to claim 1, wherein 3. The vertical length and the horizontal length are different.
A rectangular light-shielding part is provided between the vertical and horizontal directions
Photomasks that are arranged with a gap
In the light-shielding portion, in the vertical and horizontal directions of the light-shielding portion
So that they are not separated on the resist
The feature is that a slit part with a width of degree is provided.
Photomask. 4. The slit section is provided in the light shielding section.
One in each of the vertical and horizontal directions, or
4. The device according to claim 3, wherein a plurality of the plurality of coils are arranged in parallel.
Photo mask 5. A step of applying a resist to a semiconductor substrate.
And a rectangular light-shielding portion having a different vertical length and a horizontal length.
Are arranged at predetermined intervals in the vertical and horizontal directions.
Photoma containing patterns that are arranged in rows
Exposing the resist through a mask , and performing a development after the exposure process, the method for forming a pattern of a semiconductor device,
Separate the longitudinal direction of the light-shielding part on the photo mask
A slit with a fine width that does not cause resolution during exposure.
Semiconductor device characterized by performing exposure processing by providing a
Pattern formation method. 6. A step of applying a resist to a semiconductor substrate.
And a rectangular light-shielding portion having a different vertical length and a horizontal length.
Are arranged at predetermined intervals in the vertical and horizontal directions.
Photoma containing patterns that are arranged in rows
Exposing the resist through a mask , and performing a development after the exposure treatment, the method for forming a pattern of a semiconductor device,
Vertically and horizontally on the photo mask
So that they do not separate during exposure.
It is characterized by providing a slit with a width and performing exposure processing.
Pattern forming method for a semiconductor device.