JPH09288347A - Reticle with dummy pattern and semiconductor device produced by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve resolution and depth of focus, to prevent the increase in pattern areas and to improve the scale of integration of line-and-space patterns by specifying the relations between the distances between the line-and- space patterns and dummy lines, line width, space width and dummy line width. SOLUTION: The line-and-space patterns of the line width L and space width S which are mounted at a reduction stepper, are irradiated with diagonal incident illumination and are repeated with a shape long in one direction and the dummy lines having the line width below the resolution threshold of the reduction stepper on the outer side of the line-and-space patterns are arranged. Sd is <=(L+S-Ld)/2 when the distances between the line-and-space patterns and the dummy lines are defied as Sd and the line width of the dummy lines is defined as Ld. Sd is preferably 0.25xnμm to (L+S-Ld)/2 when the projection magnification of the reduction stepper is defined as 1/n times and the exposure wavelength as an (i) ray (365nm).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reticle for producing a semiconductor device and a semiconductor device employing a fine wiring formed by using the reticle.

[0002]

2. Description of the Related Art When the design rule of semiconductor is reduced to the sub-half micron rule, it has been used conventionally.
Exposure using a line (wavelength 365 nm) is approaching its limit.

Generally, the resolution R and the depth of focus are described by the Rayleigh equation for DOF. R = k1 (λ / NA) (1) DOF = k2 (λ / NA ² ) (2) where λ: wavelength, NA: numerical aperture, k1, k2: constants. As is clear from Rayleigh's equation, it is found that shortening the exposure wavelength λ is effective in producing fine wiring.

A KrF laser may be used to shorten the wavelength of light, but the chemically amplified resist used in the KrF laser has a problem of acid deactivation due to a base, a problem of dependence on a base, and a large standing wave effect, so that antireflection is prevented. There is a problem such as an increase in cost due to the necessity of a film.

Further, in the projection exposure apparatus of the KrF laser, the reliability of the narrowing of the wavelength band of the KrF laser for suppressing the chromatic aberration is insufficient, and since it is impossible to use the TTL for the alignment, it becomes off-axis. Inevitably, there are problems such as poor overlay accuracy,
Practical application is delayed. It is also possible to increase the numerical aperture NA, but now the NA is already around 0.63,
It is said that further enlargement of the lens diameter is not practical.

Therefore, as a life extension method, an exposure method utilizing two-beam imaging has been developed, which is different from normal illumination utilizing three-beam imaging. Two-beam imaging includes Levenson-type phase shift masks and oblique incidence illumination.

The Levenson-type phase shift mask reduces the diffraction angle of the ± first-order light to a value smaller than that of the three-beam image formation by inverting the phase by 180 degrees by a shifter on the reticle, and guides it to the projection lens (in this case, the zero-order light is It disappears). The Levenson type phase shift mask theoretically halves the critical resolution because the diffraction angle is halved compared to three-beam imaging. Further, since the diffraction angle becomes small, the depth of focus increases greatly. However, since the Levenson-type phase shift mask is likely to have a contradiction in shifter arrangement, it is still difficult to perform automatic placement by CAD, and it is necessary to manually correct the inconsistent portion after the shifter placement by CAD. In addition, there is a problem that a technique for producing a defect-free shifter or an inspection method therefor has not been established yet, and it is currently not used in the production line.

On the other hand, the grazing incidence illumination is to illuminate the reticle using only light in an oblique direction by blocking the central portion of the light source, and one of the ± 1st order lights of the diffracted light is outside the pupil plane of the projection lens. This is a method of forming an image with one of the 0th order light and the ± 1st order light by going out. Since one of the 0th order light and the ± 1st order light is used, the angle between the 0th order light and the ± 1st order light is made even for a fine line-and-space pattern in which the ± 1st order light protrudes from the projection lens in three-beam imaging. Can be imaged on the wafer if it can be taken into the projection lens. Therefore, the limit resolution is improved. Moreover, since the angle of incidence on the wafer is smaller than the three-beam imaging, the depth of focus is also increased.
Furthermore, since oblique incidence illumination does not require a special reticle,
The existing reduction projection exposure apparatus can be easily realized only by providing an aperture that shields the central portion of the light source. Practical use has already begun for some of the devices of the sub-half micron rule.

The oblique incidence illumination includes an annular illumination that makes the illumination annular (JP-A-61-91662) and a fourth illumination that makes a quadrant (JP-A-4-180612). This can be realized by inserting the apertures (annular illumination, fourth illumination aperture) shown in FIG. 2 in one of the front and rear and shielding the central portion of the light source.

These oblique incidences are based on the fact that the illumination light is diffracted by the reticle. The pattern with the minimum line width on the reticle is usually formed by a line-and-space pattern that is repeated in a shape that is long in one direction. Therefore, the pattern can be regarded as a diffraction grating.
The light flux can be imaged, and the resolution and the depth of focus are improved.

However, in the line and space line, the inside line can be regarded as a diffraction grating outside the pattern, but the line at the outermost side of the pattern does not form a diffraction grating outside the pattern. Cannot be specified uniquely. Therefore, it is reported that the two-beam imaging cannot be realized and the resolution and the depth of focus are deteriorated only outside the pattern.

Line width L = 0.35 μm and space width S = 0.35 μm by annular illumination using a reduction projection exposure apparatus (projection magnification 1/5) having a numerical aperture NA = 0.54 for i-line.
(L = 1.75 μm S = 1.75 μ for 5 × reticle
The result of examining the depth of focus of m) is shown in FIG. It was confirmed that the depth of focus was lower than that of the inner line.

In order to uniquely define the diffraction angle of the outermost line, it is conceivable to provide a dummy line outside the line and space pattern as shown in JP-A-6-242594 (see FIG. 4). .

In Japanese Patent Laid-Open No. 6-242594, the distance between the line and space pattern and the dummy line is s.
1, the minimum pitch of the line and space pattern is P,
If the width of the dummy line is sw1, then P / 2 ≦ s1 ≦ (P−sw1).

When a dummy line (the line width of the dummy line is αP) is provided in the line and space pattern under this condition, the pattern on the reticle is (1/2 +
α) It becomes larger by P. Therefore, considering adjacent line-and-space patterns, the distance d3 requires a distance of (1 + α) P ≦ d3 <(1.5 + 2α) P 2, and another pattern cannot be provided in this region.

On the other hand, if no dummy line is provided, d
If 3 is P / 2 or more, it can be arbitrarily set. (In the case of P / 2, it can be regarded as one line and space pattern). Therefore, when arranging a plurality of line-and-space patterns on the same reticle, Japanese Patent Laid-Open No. 6-24
In 2594, it is necessary to set the distance d3 between the line and space to (1 + α) P ≦ d3 <(1.5 + 2α) P, and the integration degree of the line and space pattern becomes worse than in the case where no dummy line is provided.

Further, in the layout work of the gate array or the like, since the pattern arrangement using the grid is performed, the grid defined by the line and space pattern (the integral multiple of 1 / 2P) is overlapped with the grid of the line and space intervals. There is a need. Therefore, the line-and-space interval becomes 1.5P, and the integration degree of the line-and-space pattern becomes worse. On the contrary, in order to increase the integration degree of the line and space pattern, it is necessary to separate the line and space pattern and the grid of the line and space intervals, which complicates the layout work.

[0018]

As described above, the pattern area becomes large in the conventional method.

An object of the present invention is to improve the resolution and the depth of focus by forming a two-beam image on the line outside the line-and-space pattern by providing a dummy line below the resolution limit of the reduction projection exposure apparatus. is there.

Further, by providing the dummy lines to prevent the pattern area from increasing, it is possible to improve the integration degree of the line and space patterns when a plurality of line and space patterns are arranged on the same reticle. is there.

Further, in the design rule of the minimum space, a smaller common grid can be adopted within the line and space pattern and at the line and space intervals, and the integration degree of the line and space pattern can be improved while the efficiency of the layout work is improved. It is to improve.

[0022]

In order to achieve the above object, the present invention is a reticle which is mounted on a reduction projection exposure apparatus and which is illuminated by oblique incidence illumination to project a pattern on a wafer. A line and space pattern consisting of a line pattern having a line width L and a space pattern having a space width S, and a dummy line having a line width below the resolution limit of the reduction projection exposure apparatus outside the line and space pattern. In the reticle in which is arranged, if the distance between the line and space pattern and the dummy line is Sd and the line width of the dummy line is Ld, then Sd is (L + S-Ld)
It is characterized in that it is / 2 or less.

Further, in a reticle mounted on a reduction projection exposure apparatus, which is illuminated by oblique incidence illumination and projects a pattern on a wafer, a line pattern having a line width L and a space having a space width S repeated in a shape elongated in one direction. In a reticle in which a line and space pattern consisting of a pattern and a dummy line having a line width equal to or less than the resolution limit of the reduction projection exposure apparatus are arranged outside the line and space pattern, the line and space pattern and the dummy line Is Sd and the line width of the dummy line is Ld, Sd becomes (L + S
-Ld) / 2.

Here, when the projection magnification of the reduction projection exposure apparatus is 1 / n and the exposure light is an i-line having a wavelength of 365 nm,
It is characterized in that Sd is in the range of 0.25 nm- (L + S-Ld) / 2.

When the projection magnification of the reduction projection exposure apparatus is 1 / n and the exposure light is a KrF laser having a wavelength of 248 nm, Sd is in the range of 0.15 nμm to (L + S-Ld) / 2. Is characterized by.

Further, when the projection magnification of the reduction projection exposure apparatus is 1 / n and the exposure light is an i-line having a wavelength of 365 nm, the line width Ld of the dummy line is 0.2 nμm or less. .

When the projection magnification of the reduction projection exposure apparatus is 1 / n and the exposure light is a KrF laser having a wavelength of 248 nm, the line width Ld of the dummy line is 0.15 nμ.
It is characterized by making it m or less.

Further, the length of the dummy line is made equal to that of the line and space pattern.

Further, a semiconductor device is manufactured by using fine wiring on a wafer formed by using a resist pattern formed from an image projected by oblique incidence illumination by a reduction projection exposure apparatus using the above reticle as an etching mask. To do.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION A reticle with a dummy pattern according to the present invention will be described in detail below with reference to the accompanying drawings. The reticle of the present invention is mounted on a reduction projection exposure apparatus and illuminated by oblique incidence illumination. A line and space pattern having a line width L and a space width S repeated in a shape elongated in one direction and the outside of the line and space pattern. In a reticle in which dummy lines having a line width less than or equal to the resolution limit of the reduction projection exposure apparatus are arranged, if the distance between the line and space pattern and the dummy line is Sd and the line width of the dummy line is Ld, then Sd becomes (L + S
-Ld) / 2 or less, which is a reticle.

In this reticle, the distance between the line and space pattern and the dummy line is Sd, the line width of the dummy line is Ld, the projection magnification of the reduction projection exposure apparatus is 1 / n times, and the exposure wavelength is i-line (365 nm). ), Sd is 0.25 × n μm to (L + S−Ld) / 2, which is a reticle.

In this reticle, the distance between the line and space pattern and the dummy line is Sd, the line width of the dummy line is Ld, the projection magnification of the reduction projection exposure apparatus is 1 / n times, and the exposure wavelength is KrF laser (248n).
m), Sd is 0.15 × n μm to (L + S−L
The reticle is characterized in that d) / 2.

In this reticle, the projection magnification of the reduction projection exposure apparatus is 1 / n and the exposure wavelength is i-line (365).
nm), the width Ld of the dummy line is 0.2 × nμ
It is a reticle characterized by being m or less.

In this reticle, if the projection magnification of the reduction projection exposure apparatus is 1 / n and the exposure wavelength is KrF laser (248 nm), the width Ld of the dummy line is 0.
The reticle has a size of 15 × n μm or less.

Further, in this reticle, the length of the dummy line is the same as that of the line and space pattern.

Further, in addition to the reticle described above, the reticle of the present invention is used to form a fine wiring on a substrate using a resist pattern formed from an image projected by oblique incidence illumination as an etching mask.

FIGS. 1A and 1B show an example of the reticle of the present invention. FIG. 1A shows a case where there is one set of line and space patterns, and FIG. 1B shows a case where there are a plurality of line and space patterns.

In FIG. 1A, a line and space pattern having a line width L and a space width S repeated in a shape elongated in one direction and a line width outside the resolution limit of the reduction projection exposure apparatus are provided outside the line and space pattern. Dummy lines (line width Ld, line length Wd) are arranged. When the distance between the line and space pattern and the dummy line is Sd, Sd is (L + S-Ld) / 2.
It is as follows.

In FIG. 1B, a line and space pattern having the same line width and the same space width is provided adjacent to the line and space pattern of interest. Consider the distance between the outermost lines of two line and space patterns as the line and space interval,
It is shown by PL.

By taking such a structure of the present invention and considering a region in which the pattern area is expanded by providing the dummy line as compared with the case of only the line-and-space pattern, L + S = 1P, so in the present invention, one side is used. The maximum is 1 / 2P + Ld.

Therefore, when a plurality of line and space patterns are arranged on the same reticle, the line and space pattern interval PL can be set to 1P or less. As a result, they have found that it is possible to improve the degree of integration of line and space patterns as compared with JP-A-6-242594.

Further, if Sd is (L + S-Ld) / 2 or less, Sd> 1 / as defined by JP-A-6-242594.
Even if it is not in the range of 2P or more, the integration degree of the line-and-space pattern is improved, and it is disclosed in JP-A-6-2425.
It was found that the same effect as 94 can be expressed.

That is, since the diffraction grating is provided on the outer side of the pattern with respect to the outermost line of the pattern, the diffraction angle becomes almost the same as the inner line, and as a result, the two-beam imaging is performed similarly to the inner line. It can be realized, the resolution of the outermost line of the pattern, the reduction of the depth of focus can be improved, and the dummy line provided outside the pattern is below the resolution limit of the reduction projection exposure apparatus, so the pattern on the reticle Does not remain as a resist pattern after development on a film on a substrate (for example, a silicon wafer, a quartz substrate, etc.) coated with a resist for projecting.

As a result, no excess pattern of the film to be etched remains on the substrate even after the film is etched. It has been found that when the film to be etched is polysilicon, it is possible to prevent the formation of an extra gate electrode, and when the film to be etched is an electrode material, it is possible to prevent the formation of an extra wiring that leads to an increase in wiring capacitance.

Especially when Sd and Ld are combined and Sd is equal to (L + S-Ld) / 2, that is, Sd + 1 /
When 2Ld = (L + S) / 2 = 1 / 2P, the line-and-space pattern interval PL can be reduced to 1P.

Therefore, when the pattern is arranged using the grid, the grid defined by the line-and-space pattern (an integer multiple of 1 / 2P) has the line-and-space interval PL overlapped by every 1.0 grid. This allows
It was found that the line and space pattern and the line and space interval can be expressed by a common grid, and the integration degree of the line and space pattern can be improved without reducing the efficiency of the layout work.

Next, the effect of the present invention will be theoretically explained from the simulation result. First, the relationship between Sd and the exposure wavelength will be described. Numerical aperture NA using i-line (wavelength 365 nm)
FIG. 5 shows the result of simulating the light intensity when the fourth illumination, which is one of the oblique incidence illuminations, is performed with the focus offset of 0 μm in the reduction projection exposure apparatus with a projection rate of 1/5 at 0.54.

The line and space pattern has a line width L = 1.75 μm and a space width S = 1.7 on the reticle.
5 sets of 5 μm (each 0.35 μm on the substrate), the dummy line Ld = 0.50 μm (0.10 μm on the substrate) on the reticle, and the distance Sd from the outside of the line and space pattern to the dummy line. (Sd on the substrate
Simulation was performed using / 5) as a parameter.

A pattern diagram is shown in FIG. 5 (a), and a simulation result is shown in FIG. 5 (b). If Sd is too small (Sd = 0.75 μm in the figure), the light intensity of the outermost space will be slightly higher, but the light intensity of the outermost line and the dummy line will not be separated, and The width of the light intensity of the line widens.

Therefore, the depth of focus of the outermost line is increased, but the line width is remarkably increased and deviates from the standard size, and cannot be adopted as a dummy line. But Sd
Is 1.25 μm or more, the light intensities of the dummy line and the outermost line are separated, so that the line width of the outermost line falls within the standard dimension.

Further, since the light intensity of the outermost space is larger than that in the case where there is no dummy line, the outermost line contrast is improved and the same degree of contrast as the inner line is obtained.

Further, since the light intensity of the dummy line is much smaller than the contrast required for resolution in the single layer resist process (usually considered to be about 0.6), it is not resolved at all. That is, it has been found that if Sd is 1.0 μm or more, it can be used as a dummy pattern.

However, when Sd is 1.75 μm or more, that is, when Sd> (L + S-Ld) / 2, the line-and-space pattern interval PL must be larger than 1P, and the grid is used to arrange the pattern. If you do, the grid (1
Since the line-and-space pattern interval PL does not overlap with the grid for every 1.0P, the common grid cannot be adopted. Therefore, it is necessary to separate the line and space pattern and the grid of the line and space intervals, which complicates the layout work and reduces the layout work efficiency. Therefore, Sd is 1.25 to
It can be seen that 1.5 μm (0.25 to 0.30 μm on the substrate) is preferable.

From the above simulation results, Sd
Is less than or equal to (L + S-Ld) / 2, then JP-A-6-24
It was found that the same effect as that of JP-A-6-242594 can be exhibited while the degree of integration of the line-and-space pattern is improved even if the range of Sd> 1 / 2P defined by 2594 is not exceeded. Especially, the projection magnification of the reduction projection exposure apparatus is set to 1
/ N times and the exposure wavelength is i-line (365 mm), Sd
Was found to be 0.25 × n μm to (L + S−Ld) / 2. Also, it has been found that only one dummy line has a sufficient effect.

Next, the case where a KrF laser (wavelength 248 nm) is used will be described. KrF laser (wavelength 248
nm), the projection magnification of NA = 0.50 is 1 /
FIG. 6 shows a result of simulating the light intensity when the fourth illumination is performed in the reduction projection exposure apparatus of No. 5 with a focus offset of 0 μm.

The line and space pattern has a line width L = 1.25 μm and a space width L = 1.2 on the reticle.
5 lines of 5 μm (0.25 μm each on the substrate), the dummy line is 0.50 μm on the reticle (0.1 μm on the substrate).
0 μm), and the distance Sd from the outside of the line and space pattern to the line below the resolution limit (Sd on the substrate
Simulation was performed using / 5) as a parameter.

When Sd = 0.5 μm, the light intensity of the outermost space is slightly increased, but the light intensity of the outermost line and the dummy line is not separated and the light intensity of the outermost line is It cannot be used as a dummy line because the width becomes wider and the line width becomes significantly larger than the standard size.

However, when Sd is 0.75 μm or more, the light intensity of the dummy line and the outermost line are separated, so that the line width of the outermost line falls within the standard dimension and there is no dummy line. Since the light intensity of the outermost space is higher than that of, the contrast of the outermost line is improved. Further, the light intensity of the dummy line is much smaller than the contrast required for resolution in the single-layer resist process, so that it is not resolved at all.

Therefore, it was found that if Sd is 0.75 μm or more, it can be adopted as a dummy pattern. But S
d is 1.25 μm or more, that is, Sd> (L + S−Ld)
In case of / 2, line and space pattern interval PL
Must be larger than 1P, and when pattern arrangement is performed using a grid, a common grid cannot be adopted, which complicates layout work. Therefore, Sd is 0.75 to 1.0 μm (0.15 to 0.2 μm on the substrate).
It turns out that m) is good.

From the above simulation results, if Sd is (L + S-Ld) / 2 or less, then Japanese Patent Laid-Open No. 6-242
It was found that even if the range of Sd> 1 / 2P defined by 594 is not satisfied, the same effect as in JP-A-6-242594 can be exhibited while the integration degree of the line and space pattern is improved. Especially, the projection magnification of the reduction projection exposure apparatus is set to 1
It was found that Sd is preferably 0.15 × n μm to (L + S−Ld) / 2 when the exposure wavelength is a KrF laser (248 nm). Also, it has been found that only one dummy line has a sufficient effect.

Next, the line width Ld of the dummy line arranged outside the line and space pattern will be described. When the exposure wavelength is i-line (365 nm), k1 described by Rayleigh's equation is 0.6 in normal illumination in a single-layer resist process using a normal novolac resist, and 0.4 to 0 in oblique illumination. It is already known to be 0.5. It is said that the NA of the reduction projection exposure apparatus has a numerical aperture NA of about 0.63 due to the large diameter of the lens and the cost of the apparatus. Therefore, the resolution limit can be estimated from Rayleigh's equation as follows. R = 0.4 to 0.6 × (0.365 × 0.63) = 0.23 to 0.29 μm

In the Rayleigh equation, the projection magnification has no relation to the resolution, and when the actual pattern layout is performed by CAD, it is usually done in the unit of 0.05 μm. Therefore, when the i-line (wavelength 365 nm) is used, If the projection magnification of the reduction projection exposure apparatus is 1 / n, the line width Ld of the dummy line arranged outside the line and space pattern is preferably 0.2 nμm or less.

Even when the exposure wavelength is a KrF laser (248 nm), k1 described by Rayleigh's equation is used in a normal single-layer resist process using a chemically amplified resist.
Is 0.4 to 0.5 when oblique incidence illumination is performed. Further, the numerical aperture NA of the reduction projection exposure apparatus is currently 0.5 to 0.55.
It is expected to be expanded to about 0.6, just like the i-line. Therefore, the resolution limit is estimated as follows. R = 0.4 to 0.6 × (0.248 × 0.6) = 0.16 to 0.21 μm

The actual pattern layout is usually 0.05
Considering that it is performed in μm units, when the KrF laser (wavelength 248 nm) is used and the projection magnification of the reduction projection exposure apparatus is 1 / n times, the line width Ld of the dummy line arranged outside the line and space pattern is Is 0.1
It is preferable that the thickness is 5 nm or less.

Next, the length Wd of the dummy line arranged outside the line and space pattern will be described. FIG. 7 shows another example of the present invention. FIG. 7A shows a case where dummy lines are provided over the entire length of the line and space pattern, and FIG. 7B shows a case where dummy lines are provided at a part of the line and space pattern.

In FIG. 7A, since the dummy lines are provided over the entire length of the line and space pattern, the contrast of the outermost line is improved over the entire length. on the other hand,
In FIG. 7B, there is a part of the outermost line that is adjacent to the outermost line, so that the contrast of the outermost line is not improved in that part. Therefore, in order to improve the contrast of the outermost line over the entire length of the line and space pattern, the length Wd of the dummy line needs to be the same as the line and pace pattern.

However, in an actual pattern layout, there are cases where dummy lines cannot be arranged adjacent to the line and space pattern due to the density of the periphery of the line and space pattern. In that case, divide the dummy line in the length direction and place it as close to the line and space pattern as possible, or increase the width of the outermost line of the line and space where the dummy line cannot be provided. Good to do.

When oblique illumination such as annular illumination or fourth illumination is performed using the reticle of the present invention, the resolution and depth of focus of the projected image are improved. Therefore, when a projected image is formed on the resist applied to the film on the substrate and developed with a developing solution, a finer resist pattern can be formed. Therefore, when using the resist pattern as an etching mask to etch the above-mentioned film and create wiring from the film to be etched, it is possible to make it smaller than the wiring made from the pattern on the reticle that does not have lines below the resolution limit. It is possible.

For example, when the present invention is used in the exposure process of the gate electrode and the metal wiring of the semiconductor device, the gate electrode and the metal wiring can be miniaturized, and high speed, low power consumption and integration of the semiconductor can be expected. Although the description of the present invention is centered on the fourth illumination, the same effect can be expected in the case of oblique incidence illumination, so that even annular illumination, cross-shaped illumination, or single-character illumination is used. I do not care.

[0070]

Next, the present invention will be described in more detail with reference to examples. Example 1 In a 5 × reticle made of quartz of 5009 (5 inch square, thickness 0.9 mm), a line width L = 1.75 μm,
Dummy lines with a line width Ld = 0.50 μm were provided outside the line-and-space pattern of five sets with a space width S = 1.75 μm at intervals of Sd = 0 to 1.50 μm. This reticle was mounted on a reduction exposure projection apparatus with NA = 0.54 for i-line (wavelength 365 nm) having a projection magnification of ⅕, and the fourth illumination was performed. As a substrate, a silicon substrate coated with an i-ray resist of 1.05 μm was used, and exposure was performed while changing the focus position. PEB at 110 ° C. for 60 seconds
Then, after developing for 1 minute with a 2.38% solution of TMAH, S
The depths of focus on the outside and inside of the line of five groups were measured by observing the cross section with EM.

The resolution of the line-and-space pattern was conditioned on the condition that the resist size is ± 10% of the design size and there is no resist film reduction. Further, even if a part of the dummy line has a resist pattern, it was resolved. The results are shown in Fig. 8.

When Sd is 0.25 to 1.00 μm, the outer line is separated from the adjacent line in the focal range of about 1.5 to 2 μm, but since the resist size exceeds + 10% of the design size, the depth of focus is reduced. No improvement was obtained. However, when the distance between the line and space pattern and the dummy line is 1.25 to 1.50 μm, the resist size of the line outside the set of 5 line and space patterns comes to be within ± 10% of the design size. The depth of focus is improved. When Sd = 1.25 to 1.50 μm, the adjacent line and space pattern intervals PL are set to 3.0.
And 3.5 μm (that is, 1 P or less).

Example 2 In a 5 × reticle made of quartz of 5009 (5 inch square, thickness 0.9 mm), a line width L = 1.75 μm,
Dummy lines having a line width Ld = 0 to 1.50 μm were provided outside the five-line and space pattern having a space width S = 1.75 μm at intervals of Sd = 1.25 μm. This reticle was attached to a reduction projection exposure apparatus with an NA of 0.55 for i-line (wavelength 365 nm) having a projection magnification of 1/5, and annular illumination with an annular zone ratio of 1/2 was performed. A silicon substrate coated with an i-ray resist of 1.05 μm was used as a substrate, and exposure was performed while changing the focal position.
After PEB for 2 seconds, after developing with a TMAH 2.38% solution for 1 minute, the depths of focus on the outside and inside of the line of 5 groups were measured by cross-sectional observation by SEM. The results are shown in Fig. 9.

When the width of the dummy line was 1.00 μm or less, the dummy line could not be resolved on the silicon substrate, and the reduction in the depth of focus of the line outside the line and space pattern of 5 groups could be improved.

Example 3 In a 5 × reticle made of 5009 (5 inch square, 0.9 mm thick) reticle, the line width L = 1.25 μm,
Sd = 0.00 to 1.00 μm on the outside of the line-and-space pattern of 5 pieces with space width S = 1.25 μm
Dummy lines having a line width Ld = 0.50 μm were provided at intervals of. The projection magnification of this reticle is 1/5.
It was mounted on a reduction projection exposure apparatus of NA = 0.50 of an F laser (wavelength 248 nm), and the fourth illumination was performed. As the substrate, a silicon substrate coated with a chemically amplified resist for KrF of 0.85 μm was used, exposed while changing the focus position, PEB at 110 ° C. for 60 seconds, and then developed with a 2.38% solution of TMAH for 1 minute, and then SEM. 5 from cross-section observation
The depth of focus outside and inside the line of this set was measured. The results are shown in FIG.

When Sd is 0.25 to 0.50 μm, the outer line is separated from the adjacent line in the focal range of 1.6 μm or more, but the resist size exceeds + 10% of the design size, so that the depth of focus is improved. I couldn't get it. However, the distance between the line and space pattern and the dummy line is 0.7.
In the case of 5 to 1.00 μm, the resist size of the line outside the line and space pattern of 5 sets comes to be within ± 10% of the design size, and thus the depth of focus is improved.
When Sd = 0.75 to 1.00 μm, adjacent line and space pattern intervals PL are set to 2.0 and 2.5, respectively.
It can be made to be μm (that is, 1 P or less).

Example 4 In a 5 × reticle made of quartz of 5009 (5 inch square, thickness 0.9 mm), the line width L = 1.25 μm,
Dummy lines with a line width Ld = 0 to 1.25 μm were provided outside the five-line and space pattern with a space width S = 1.25 μm at intervals of Sd = 0.75 μm. This reticle was mounted on a reduction projection exposure apparatus of NA = 0.50 of a KrF laser (wavelength 248 nm) having a projection magnification of ⅕, and the fourth illumination was performed. As the substrate, a silicon substrate coated with a chemically amplified resist for KrF of 0.85 μm is used, and exposure is performed while changing the focal position.
After PEB at 110 ° C. for 60 seconds, development with a TMAH 2.38% solution for 1 minute was performed, and then the depths of focus on the outside and inside of the set of 5 lines were measured by cross-sectional observation by SEM. The results are shown in Fig. 11.

When the width of the dummy line was 0.75 μm or less, the dummy line was not resolved on the silicon substrate, and the decrease in the depth of focus of the line outside the line and space pattern of 5 groups could be improved.

Example 5 Al of the first layer of a gate array having a gate length of 0.35 μm
In the exposure of the wiring, the reduction projection exposure apparatus (i line, NA =
At 0.55), annular illumination with an annular ratio of 2/3 was performed. Al
1.8 μm of i-line resist was applied on the film, and after exposure 11
PEB was performed at 0 ° C. for 60 seconds, development was performed with a TMAH 2.38% solution for 1 minute, and then post-baking was performed at 120 ° C. for 60 seconds.

The pattern on the reticle has a line width L = 2.
The line and space pattern of 00 μm and space width S = 2.00 μm is used to form a dummy line (L
d: the width of the dummy line, Sd: the distance between the dummy line and the line and space pattern) B and C, and A not provided. A plurality of line and space patterns are formed with the line and space pattern intervals PL shown in FIG.

The reticle of the present invention is C. After forming the resist pattern, the resist is thermally cured by irradiating it with UV light while heating it to 200 ° C., and then using a magnetic field magnetron reactive ion etching apparatus, BCl ₃ ,
Al etching was performed with Cl ₂ and CHF ₃ gases to form Al wiring. After that, an interlayer insulating film (N
SG 0.8 μm) and a second layer of Al wiring were formed and covered with a passivation film (Si ₃ N ₄ 0.5 μm) to evaluate the yield.

The main cause of the yield reduction in reticle A is the open / short defect of the first layer Al wiring due to the insufficient depth of focus of the line outside the line and space pattern. Therefore, by using the reticles B and C provided with the dummy patterns, the miniaturization of the first layer Al wiring can be realized with a high yield. Furthermore, by using the reticle C of the present invention, the chip area is 5
% Reduction has been achieved.

[0083]

The effects of the present invention described above will be described below. Effect of the Invention of Claim 1: When oblique incidence illumination is performed using the reticle of claim 1, when a plurality of line and space patterns are arranged on the same reticle, the line and space pattern interval PL is set to 1P or less. It is possible to improve the integration degree of the line and space pattern. Further, even if the range of Sd> 1 / 2P defined by JP-A-6-242594 is not exceeded, the same effect as that of JP-A-6-242594 can be exhibited while the degree of integration of the line and space pattern is improved. That is, since the diffraction grating is provided on the outer side of the pattern with respect to the outermost line of the pattern, the diffraction angle becomes almost the same as the inner line, and as a result, two-beam imaging can be realized similarly to the inner line. The resolution of the outermost line and the decrease in the depth of focus can be improved, and because the dummy line provided outside the pattern is below the resolution limit of the reduction projection exposure apparatus, the resist that projects the pattern on the reticle After the development, the resist pattern does not remain on the film on the substrate coated with (eg, silicon wafer, quartz substrate, etc.). as a result,
Even after the film is etched, an excess pattern of the film to be etched does not remain on the substrate. When the film to be etched is polysilicon, it is possible to prevent the formation of extra gate electrodes, and when the film to be etched is an electrode material, it is possible to prevent the formation of extra wiring that increases the wiring capacitance.

Effect of the invention of claim 2 When oblique illumination is performed using the reticle of claim 2, Sd becomes (L +
Since it is equal to S-Ld) / 2, the line-and-space pattern interval can be reduced to 1P. Therefore, when pattern arrangement is performed using a grid, the line and space pattern interval is 1.0 P in the grid (integer multiple of 1 / 2P) defined by the line and space pattern.
Since each grid overlaps, it becomes possible to set the line-and-space pattern interval to 1.0P, and as a result, the integration degree of the line-and-space pattern can be improved without reducing the efficiency of the layout work.

Effect of the third aspect of the invention: When oblique incidence illumination is performed by the i-line reduction projection exposure apparatus using the reticle of the third aspect, the light intensities of the dummy line and the outermost line are separated. Therefore, the line width of the outermost line comes to be within the standard dimension, and the light intensity of the outermost space becomes larger than that when there is no dummy line.
The contrast of the outermost line is improved, and the focus depth is improved.

The effect of the invention of claim 4: When oblique incidence illumination is performed by the reduction projection exposure apparatus of the KrF laser using the reticle of claim 4, the light intensity of the dummy line and the outermost line are separated. Therefore, the line width of the outermost line comes to be within the standard dimension, and the light intensity of the outermost space becomes larger than that when there is no dummy line, so the contrast of the outermost line is increased. Is improved,
The depth of focus is improved.

The effect of the invention of claim 5: When the reticle of claim 5 is used to perform oblique incidence illumination by a reduction projection exposure apparatus for i-line, the contrast of the outermost line of the line and space pattern is lowered. As a result, the resolution and depth of focus of the outermost line of the line and space are improved. On the other hand, the dummy lines arranged outside the line and space pattern are not resolved because they are below the resolution limit of the i-line reduction projection exposure apparatus.

Effect of the invention of claim 6: When oblique incidence illumination is performed by a reduction projection exposure apparatus of a KrF laser using the reticle of claim 6, the contrast of the outermost line of the line and space pattern is lowered. Since this can be improved, the resolution and the depth of focus of the outermost line of the line and space pattern are improved. On the other hand, the dummy line arranged outside the line and space pattern is Kr.
It is not resolved because it is below the resolution limit of the F laser reduction projection exposure apparatus.

Effect of the invention of claim 7 of the present invention: claim 7
When oblique incidence illumination is performed using the reticle described in, the decrease in contrast of the outermost line of the line and space pattern can be improved over the entire length of the line and space pattern. The line resolution and depth of focus are improved over the entire length of the line and space pattern.

Effect of the invention of claim 8 of the present invention: Further, the fine wiring described in claim 8 can be made finer than a wiring made from a pattern on a reticle not provided with lines below the resolution limit. is there. Therefore, for example, when the present invention is used in the exposure process of the gate electrode and the metal wiring of the semiconductor device, the gate electrode and the metal wiring can be miniaturized, and high speed, low power consumption and integration of the semiconductor device can be expected.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a reticle of the present invention.

FIG. 2 is an explanatory diagram showing an example of an aperture of a conventional annular illumination and a fourth illumination.

FIG. 3 is a diagram showing a depth of focus of a conventional fourth oblique illumination.

FIG. 4 is an explanatory diagram showing an example of a conventional dummy pattern.

FIG. 5 is an explanatory view showing a pattern of a reticle with a dummy pattern according to an embodiment of the present invention and a simulation result of light intensity at the i-line by the reticle.

6 is an explanatory diagram showing a simulation result of light intensity in a KrF laser using the reticle of FIG.

FIG. 7 is an explanatory view showing a pattern of a reticle with a dummy pattern according to another embodiment of the present invention.

FIG. 8 is a chart showing the measurement results of one example of the present invention.

FIG. 9 is a chart showing measurement results of another example of the present invention.

FIG. 10 is a chart showing measurement results of still another example of the present invention.

FIG. 11 is a chart showing measurement results of still another example of the present invention.

FIG. 12 is a chart showing the determination results of the yields of a plurality of reticles according to the present invention.

[Explanation of symbols]

1 line 2 space 3 dummy line L line width Ld dummy line width P line and space width S space width Sd distance between line and space pattern and dummy line Wd line length

Claims (8)

[Claims] 1. A reticle mounted on a reduction projection exposure apparatus, which is illuminated by oblique incidence illumination and projects a pattern on a wafer, wherein a line pattern having a line width L and a space having a space width S repeated in a shape elongated in one direction. A line and space pattern consisting of a pattern, and a reticle having a dummy line having a line width equal to or less than the resolution limit of the reduction projection exposure apparatus outside the line and space pattern, wherein the line and space pattern and the dummy line The reticle is characterized in that Sd is (L + S-Ld) / 2 or less, where Sd is the distance from the line and Ld is the line width of the dummy line. 2. A reticle mounted on a reduction projection exposure apparatus, which is illuminated by oblique incidence illumination and projects a pattern on a wafer, wherein a line pattern having a line width L and a space having a space width S repeated in a shape elongated in one direction. A line and space pattern consisting of a pattern, and a reticle in which a dummy line having a line width equal to or less than the resolution limit of the reduction projection exposure apparatus is arranged outside the line and space pattern, wherein the line and space pattern and the dummy line Is Sd and the line width of the dummy line is Ld, Sd becomes (L
Reticle equal to + S-Ld) / 2. 3. The projection magnification of the reduction projection exposure apparatus is 1 /
The reticle according to claim 1 or 2, wherein Sd is in a range of 0.25 nµm to (L + S-Ld) / 2 when the exposure light is an i-line having a wavelength of 365 nm and n times. 4. The projection magnification of the reduction projection exposure apparatus is 1 /
The reticle according to claim 1 or 2, wherein Sd is within a range of 0.15 nμm to (L + S-Ld) / 2 when a KrF laser having a wavelength of 248 nm is used as the exposure light of n times. 5. The projection magnification of the reduction projection exposure apparatus is 1 /
The line width Ld of the dummy line is set to 0.2 nμm or less when the exposure light is an i-line having a wavelength of 365 nm and n times as large as the exposure light.
Reticle described. 6. The projection magnification of the reduction projection exposure apparatus is 1 /
When a KrF laser with a wavelength of 248 nm is used as n times the exposure light, the line width Ld of the dummy line is 0.15 nμm.
The reticle according to claim 1 or claim 2 or claim 4, wherein: 7. The reticle according to claim 1, wherein the dummy line has a length equal to that of the line and space pattern. 8. Fine wiring on a wafer formed using a resist pattern formed from an image projected by oblique incidence illumination by a reduction projection exposure apparatus using the reticle according to claim 1 as an etching mask. A semiconductor device characterized by using.