JPH06140307A - Optical exposure method - Google Patents

Abstract

PURPOSE:To enable projection exposure in a modified illumination system most suitable for each device pattern by obliquely irradiating a photomask having a periodic pattern at a specific angle to the optical axis. CONSTITUTION:A line-and-space pattern 23, composed of translucent and shielding stripes 21 and 22, respectively, is formed on a photomask 5. Two linear slits are formed in an iris point-symmetrically with respect to the optical axis of the optical aligner and parallel with each other. Light is projected to the photomask 5 through a condenser lens 3 at an incidence angle theta to the optical axis of the optical aligner, as expressed by the formula. In the formula NA is the number of slits in the projection optical system, R the reduction ratio thereof, P the pitch of the line and space on the projection plane, and lambdathe wavelength of projected light. This makes it possible to make effective use of the merits of oblique incidence.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to photolithography in microfabrication in the manufacture of semiconductor devices, and more particularly to an optical exposure method in photolithography.
The progress of high integration and fine processing in semiconductor devices such as VLSI depends greatly on the improvement of lithography technology. Among them, optical lithography using light is suitable for mass production and is also adopted for economic reasons. , And research and development for further improvement are being conducted.

[0002]

2. Description of the Related Art FIG. 1 is a schematic view of a light exposure apparatus (stepper), which is a modified illumination system 4 including a light source 1 of a mercury lamp (excimer laser), a diaphragm 2 having a through hole, and a condenser lens 3. It is composed of a photomask (reticle) 5 having a predetermined pattern, a projection lens 6 and a resist film (projection surface) 7 applied on the substrate. In this case, due to the modified illumination, the position of the through hole of the diaphragm 2 is displaced from the optical axis of the device, and the incident light on the photomask is oblique. It coincides with the optical axis of the device, and the incident light on the photomask is vertical. Further, a compound eye condensing lens (fly's eye lens) may be arranged between the light source and the diaphragm as in the conventional light exposure apparatus.

In the case of FIG. 1, the shape of the light source is defined by the shape of the through hole of the diaphragm, but by using a fly-eye lens,
The individual monoculars may be arranged in a desired light source shape (through hole shape). When changing the shape of the light source according to the intended use, if a diaphragm is used, it may be replaced with a diaphragm having a different through-hole shape. Alternatively, an opening / closing function may be added to each of the monoculars 11a to 11f of the fly-eye lens 11 (FIG. 2). For example, the liquid crystal plate 12 is arranged at the exit or entrance of the monocular of the fly-eye lens, and a voltage is applied to the electrode 13 at a place corresponding to the monocular to transmit or block light.

In the ordinary light exposure technique, as shown in FIG. 3, light is incident on the back surface of the photomask 5 perpendicularly to the mask 5 and the diffracted light emitted therefrom is projected as shown in FIG. A system (projection lens) 6 collects the light and a pattern is imaged on a projection surface (corresponding to a resist film) 7. Note that, in FIG. 3, for simplicity, 0th-order, −1st-order, and −2nd-order diffracted lights are shown, and 1st-order and 2nd-order diffracted lights are omitted.
Then, as shown in FIG. 4, for a diffraction angle φ ₁ of a certain diffracted light (for example, first-order diffracted light) and an angle φ _{2 at} which it is condensed by the projection optical system, Rφ ₁ = φ ₂ There is a relation of R: reduction ratio of the projection optical system, but since the reduction ratio is not essential in the present invention, R = 1 (1 × projection) will be described in all cases.

In order to increase the resolution in the optical exposure technique, it is important to increase the numerical aperture (NA) of the lens and shorten the wavelength of the light source. On the other hand, the depth of focus will decrease with increasing NA. Therefore, the modified illumination method (illumination method of oblique incidence) that improves the limit resolution and the depth of focus has recently received attention (see, for example, Nikkei Microdevice, No. 82, April 1992, pp.28-37). .

As a hole shape in a diaphragm (aperture) in the modified illumination method, a ring-shaped hole and a point-symmetrical four hole are known. In the conventional illumination method, the illumination light from the circular hole that coincides with the optical axis of the exposure apparatus is vertically incident on the photomask (reticle). Basically, as shown in FIG. 4, the 0th order light emitted from the photomask is used. , + 1st order light and −
Although an image is formed with three primary light beams, in the modified illumination method,
The position of the hole of the diaphragm is shifted from the optical axis, and as shown in FIG. 5, the illumination light from the hole obliquely enters the photomask, and the 0th order light and the + 1st order light ( Alternatively, the image is formed with two light fluxes (or −1st order light). The conventional illumination method has a higher contrast at the focus position, but the modified illumination method has a higher contrast at the defocus position, and thus the depth of focus and the resolution are comprehensively improved.

[0007]

In the conventional modified illumination method, only the pattern of the simple line and (&) space is used, and the pattern of the photomask is used as the resist with the above-described almighty type aperture hole shape. Projection exposure. Therefore, the illumination system has not yet been adapted to the individual pattern shape, and the effect of oblique incidence in the modified illumination method is not maximized.

An object of the present invention is to provide a method of projection exposure with a modified illumination system that is most suitable for a device pattern (photomask pattern), particularly a line & space where the line width and the space width are not equal.

[0009]

The above-mentioned object is to provide a light source,
Using a modified illumination system consisting of a diaphragm and a condenser lens, an exposure device consisting of a photomask and a projection lens,
In the method of projecting and exposing a pattern of the photomask onto a resist on a substrate, when the pattern of the photomask is a periodic pattern, the photomask is obliquely irradiated at an angle θ with respect to the optical axis, and sin ⁻¹ NA ≧ Rθ ≥ sin ^-1 (2λ / P) − sin ^-1 NA where NA: Numerical aperture of the projection optical system R: Reduction ratio of the projection optical system P: Line-and-space pitch on the projection surface λ: Projection light This is achieved by an optical exposure method characterized by having a wavelength relationship.

The illumination form corresponding to the shape of the light source is set as one linear light illumination parallel to the pattern of the photomask at a position away from the optical axis of the exposure device, and the exposure is performed on the optical axis of the photomask. On the other hand, it is preferable to perform the oblique incidence illumination with the angle θ described above. Further, it is more preferable that the same linear light illumination is added in parallel and at a position line-symmetrical with respect to the optical axis of the exposure device to obtain two linear light illuminations.

It is also possible to illuminate one circular light at a position away from the optical axis of the exposure apparatus and set the angle of light incident on the photomask from the center of the illuminating light to the above-specified angle θ. Further, the same circular light illumination can be added at positions symmetrical with respect to the exposure optical axis to form two circular light illumination. Furthermore, in the photomask,
If the periodic pattern of the X-axis direction pitch Px and the periodic pattern of the Y-axis direction pitch Py are mixed or there is the pattern of the X-axis direction pitch Px and the Y-axis direction pitch Py, the optical axis of the exposure apparatus On the other hand, four circular light illuminations on concentric circles and at equal intervals are performed, and from the center of each of the illumination light, the angle of light incident on the photomask is orthogonal to the X direction and the Y direction. Angle θ
There is a relation of sin ^-1 NA ≥ R θx ≥ sin ^-1 (2λ / Px) − sin ^-1 NA sin ^-1 NA ≧ R θy ≧ sin ^-1 (2λ / Py) − sin ^-1 NA at x and angle θy Light exposure methods are preferred.

Then, one ring-shaped light illuminating at a position on a concentric circle with respect to the optical axis of the exposure apparatus is performed, and the angle of the light incident on the photomask from the center of the ring width of the ring-shaped illumination light is set to It is also possible to set the prescribed angle θ.

[0013]

In the light exposure method of the present invention, as shown in FIG.
In order to form an image with three light fluxes of diffracted light of 0th order, 1st order and 2nd order, the oblique incident angle θ at which higher order diffracted light can be used is defined as “sin ⁻¹ NA ≧ R θ ≧ sin ⁻¹ ( 2θ / P) − sin ⁻¹ NA ”is set in the range of θ, so both resolution and depth of focus are increased by incorporating high-order light. In this case, θ = β−sin ⁻¹ NA β = sin ⁻¹ (2λ / P) Therefore, θ = sin ⁻¹ (2λ / P) −sin ⁻¹ NA is obtained.

The NA of the projection optical lens is sin of the light entering the outermost circumference of the lens, and the upper limit of the incident angle θ is sin ^-1 NA ≥ when the 0th order light enters the outermost circumference of the projection optical system lens. θ
(R = 1). The lower limit of the incident angle θ is when the secondary light is incident on the outermost circumference of the projection optical system lens. This is effective when the line / space ratio of the photomask pattern is not 1: 1 (for example, when the ratio is different such as 0.2: 0.8). The line and space pattern is a pattern in which a plurality of relatively linear light-shielding (or transmitting) stripes are repeated on a photomask and arranged in parallel at a constant pitch P (the total of lines and spaces). Equivalent to.

The wavelength λ of the exposure light source (light) is the g-line (434n).
m), i-line (365 nm) or excimer laser (Kr
It becomes constant at 254 nm of the F excimer laser), and the range of the incident angle θ is determined according to the pattern pitch P.

[0016]

EXAMPLES The present invention will be described in detail below with reference to the accompanying drawings by way of example embodiments and comparative examples of the present invention. The optical exposure apparatus (stepper) used has the structure shown in FIG. 1, and in the present invention, the shape of the through hole in the diaphragm 2 is different from the conventional one, which is a structural difference. As shown in FIG. 2, a compound eye condensing lens (fly's eye lens) with an opening / closing function for each monocular can be used to form a predetermined light source shape (corresponding to a through hole shape).

Example 1 A photomask 5 is provided with a transparent stripe 2 as shown in FIG.
A line-and-space pattern 23 composed of 1 and a light-shielding stripe 22 is formed by a known method. For example, a photomask 5 is formed by forming a chromium light-shielding film of this pattern on quartz glass. In this case, the ratio of the line width A to the space width B is made different, for example, 0.2: 0.8, and the repetitive pattern 23 with a constant pitch p is formed.
And In order to obtain the light illumination according to the present invention, FIG.
As shown in FIG. 3, two linear through holes 32 are provided in the diaphragm 31 in point symmetry with respect to the optical axis of the light exposure apparatus and in parallel with each other.
Therefore, two slits are formed in the light-shielding diaphragm, and the light from the light source 1 passes through these slits and enters the condenser lens 3. The diaphragm 31 is arranged so that these linear through holes 32 are parallel to the line and space pattern 23 of the photomask. It should be noted that two linear through holes 34 shown in FIG.
A diaphragm 33 having the following is set.

Then, the condenser lens 3 illuminates the photomask 5 at an incident angle θ, and the incident angle θ is an angle with the optical axis of the photoexposure device in the photomask.
In the present invention, this incident angle θ is defined as sin ⁻¹ NA ≧ R θ ≧ sin ⁻¹ (2λ / P) − sin ⁻¹ NA, where NA: numerical aperture R of the projection optical system R: reduction ratio P of the projection optical system : Line-and-space pitch on the projection surface λ: Range specified by the wavelength of projection light. Next, the 0th, 1st, and 2nd order diffracted lights from the photomask 5 hit the projection lens 6, and these diffracted lights are condensed by the lens to form a pattern on the resist film 7 on the projection surface. Become. The pattern 23 of the photomask 5 is projected and exposed on the resist film 7 on the substrate such as a semiconductor wafer and developed to obtain a resist pattern.

A light exposure simulation was performed under the following conditions, and the projection surface of the resist film was set as a line &
Fig. 9 (a) shows the light intensity in the direction perpendicular to the space pattern.
~ (D). Light source wavelength (λ) i-line (0.36
5 μm) Lens aperture (NA) …… 0.5 Coherence factor (σ) …… 0.5 Line and space setting pitch (p) …… 1.0 μm Line width …… 0.2 μm Space width …… 0.8 μm Incident angle (θ) …… 16 degrees (on wafer) (An angle larger than that calculated from 2 × 1.0 × sin θ = 0.365.) Figure 9 (a) shows the focus position ( In Fig. 9 (b), the defocus is 0.
The light intensity at 5 μm is shown, and in FIG.
The light intensity at 1.0 μm is shown, and in FIG. 9D, the light intensity at a defocus of 1.5 μm is shown. These FIG. 9 (a)
As can be seen from (d), the light intensity profiles are similar and the depth of focus is large.

As Comparative Example 1, as a diaphragm 41 having a transparent hole 42 for simulation shown in FIG. 10, a conventional round hole diaphragm (σ = 0.5) was used with the same photoexposure device and the same photomask. When light exposure is performed, the light intensity on the projection surface of the resist film at the focus position and the defocus position is shown in FIG.
1 (a) to (d). In FIG. 11A, the light intensity at the focus position (without defocus) is shown in FIG.
1 (b) shows the light intensity when the defocus is 0.5 μm,
11C shows the light intensity when the defocus is 1.0 μm, and FIG. 11D shows the light intensity when the defocus is 1.5 μm. As can be seen from these FIGS. 11A to 11D, the contrast is large when there is no defocus, but the profile of the light intensity becomes larger as the defocus increases.
The level of light intensity (contrast) becomes small, and the resolution decreases. Naturally, the depth of focus is smaller than in the present invention.

As Comparative Example 2, as shown in FIG. 12, the same light exposure is performed by using a diaphragm 51 having two linear light transmitting holes 52 similar to the diaphragm of FIG. 8B in the present invention. When light exposure simulation is performed by the apparatus, the light intensity on the projection surface of the resist film is shown in FIG.
To (d). In addition, in this diaphragm 51,
The incident angle θ is set to θ = sin ⁻¹ (λ / 2p), and basically two diffracted lights of 0th order and + ^1st order are used.

FIG. 13A shows the light intensity at the focal position (without defocus), and FIG. 13B shows the defocus.
13 shows the light intensity at 0.5 μm, FIG. 13 (c) shows the light intensity at a defocus of 1.0 μm, and FIG. 13 (d) shows the light intensity at a defocus of 1.5 μm. . These Figure 1
As can be seen from 3 (a) to 3 (d), even if the defocus of the light intensity profile is large, the deterioration of the high / low (contrast) of the light intensity is small as compared with the above-described Example 1 and Comparative Example 1. The depth of focus is large as in the case of the present invention.
However, in a line and space like 2: 8,
As will be described later, there are only two Fourier spectra that can be taken into the lens (Fig. 15 at the diaphragm 63 in Fig. 14C).
Since (c)), an image represented by only one sine curve is projected. This light intensity is not suitable for forming a 2: 8 line & space pattern (note that it is suitable for the case of 1: 1).

Example 2 In the light exposure apparatus using the photomask 5 in Example 1, lines and spaces were projected according to the number (one or two) of linear through holes in the diaphragm and their positions. In this case, we simulate how the spectral intensity on the pupil (projection lens) will be. First, as shown in FIG. 14, in the diaphragms 61 to 66, one linear through hole 71 to 76 is provided from the center position to the outer position.
14A to 14C are comparative examples, and FIGS. 14D to 14F show the case according to the present invention. Particularly, the diaphragm 63 of FIG.
In, the linear through hole 73 is provided at a position where the incident angle θ is θ = sin ⁻¹ (λ / 2p).

FIGS. 15A to 15C and FIG. 16A.
The Fourier spectra shown in ~ (c) are shown in Fig. 1.
It corresponds to the diaphragms 61 to 66 of 4 (a) to (f). As can be seen from the Fourier spectra in FIGS. 15A to 15C in the case of the present invention, there are two small peaks on the right side of one high peak. On the other hand, FIG.
In FIG. 15C, there is one small peak on the right side of the high peak, and FIGS. 15A and 15B of the diaphragms 61 and 62 are shown.
, There are two small peaks on both sides of the high peak. If there are only two Fourier spectra, the light intensity distribution has a sine curve as shown in FIG. This is 1: 1
It is not suitable for forming patterns other than the line and space pattern of. In the case of three Fourier spectra of the 1st, 0th and -1st order, the light intensity distribution is as shown in FIG.
The depth of focus is low. In the case of three Fourier spectra of 0th order, 1st order and 2nd order, a wide depth of focus can be obtained as shown in FIG.

In order to use three Fourier spectra of the 0th order, the 1st order and the 2nd order for imaging, NA is larger than λ / P and θ is the above expression sin ⁻¹ NA ≧ Rθ ≧ sin ⁻ It must be in the range of ¹ (2λ / P) − sin ⁻¹ NA. Next, from FIG.
As shown in (e), in the diaphragms 81 to 85, two linear through holes 91 to 95 are symmetrically arranged from the central position to the outer position, and FIGS. 17 (a) and 17 (b) show a comparative example. ,
17C to 17E show the case according to the present invention. Practically, the aperture of two linear through holes is preferable because the amount of light is small in one linear through hole and the two linear through holes are symmetrical with respect to the optical axis and balanced. . In the diaphragm 82 of FIG. 17B, the incident angle θ is θ = sin
Two linear through holes 92 are provided at a position of ^-1 (λ / 2p).

18 (a) and (b) and FIG. 19
The light intensity spectra shown in (a) to (c) correspond to the diaphragms 81 to 85 in FIGS. 17 (a) to (e), respectively.
These spectra are obtained by superimposing the symmetric spectra in the spectra (FIGS. 17 (a) to (c) and 16 (a) to (c)) in the case of one linear through hole. Note that the diaphragms 81 to 85 (FIGS. 14A to 14E are respectively shown in FIG.
It corresponds to the diaphragms 62 to 66 of (b) to (f).

In the present invention, as shown in FIG. 6, an image is formed by diffracted light of 0th order, 1st order and 2nd order. In addition, FIG.
As shown in (c), the 0th-order diffracted light and the 1st-order and 2nd-order diffracted lights have greatly different intensities. Therefore, FIG. 14 (d)
In the light source using the diaphragm of (f), the light intensity distribution may be asymmetrical. This is particularly likely to occur when there is defocus. This problem is solved by making the linear through holes (light source shape) symmetrical as shown in FIG. An example is shown in Example 3 below.

Example 3 In the optical exposure apparatus using the photomask 5 in Example 1, the shape of the diaphragm is shown in FIGS. 14 (a) to (f) and FIG.
As (a) to (e), light exposure simulation was performed under the conditions of Example 1, and the projection surface of the resist film was focused at the focal position of the projection lens and at a position defocused by 1.0 μm (focal position). 20 (a) to 20 (c) and 21 (a) to 21 (a) to 21 (a) to 21 (c).
(C), FIG. 22 (a) and (b) and FIG. 23 (a)
~ (C). 21A to 21C show the light source shown in FIG.
When (d) to (f) are used, it is shown that the light intensity distribution becomes asymmetrical due to the defocus of 1 μm.
The position of the pattern (the point where the light intensity is the minimum) when a positive resist is used has also moved due to defocus. 23 (a) to 23 (c) show that the light sources of FIGS. 20 (c) to 20 (e) are used and the light intensity distribution is bilaterally symmetrical even if there is defocus. However, in the light source of FIG. 17E, the contrast is remarkably lowered due to the defocus of 1 μm.

Example 4 On the photomask 5, a line-and-space repeating pattern composed of a light-shielding line pattern 101 and a through hole (space) pattern 102, which are periodically arranged at regular intervals as shown in FIG. A pattern 103 corresponding to a word line is formed by a known method. In order to obtain the optical illumination according to the present invention, a light exposure simulation is performed under the following conditions with the light exposure apparatus according to the first embodiment using the diaphragm 33 (two linear through holes) in FIG. 8B. 25, 26 and 27 show the three-dimensional light intensity distribution along the isointensity line, with the projection surface of the resist film as the focal position of the projection lens and the position displaced (defocused) from it.

Wavelength of light source (λ) ... i-line (0.36)
5 μm) Lens aperture (NA) …… 0.57 Coherence factor (σ) …… 0.5 Line and space setting pitch (p) …… 0.90 μm
(Cycle 1.8 μm) Line width …… 0.3 μm Minimum space width …… 0.5 μm Incident angle (θ) …… 18 degrees (Calculated from 2 × 0.9 × sin θ = 0.365, In Fig. 25, the focus position (no defocus)
26 shows the light intensity distribution, and in Fig. 26, the defocus is 0.4μ.
27 shows the light intensity distribution at m and in FIG.
The light intensity distribution at 0.8 μm is shown. As can be seen from these, the shape of the light intensity distribution is almost the same, and the depth of focus is large.

As a comparative example, when the same light exposure apparatus is used to perform light exposure using a conventional round-hole diaphragm (σ = 0.5), the light intensity distribution on the projection surface of the resist film shows the focal position and defocus. The position is as shown in FIGS. 28, 29 and 30. 28 shows the light intensity distribution at the focal position (without defocus), FIG. 29 shows the light intensity distribution at the defocus of 0.5 μm, and FIG. 30 shows the light intensity at the defocus of 1.0 μm. The distribution is shown. As can be seen from these FIG. 25 to FIG. 30, the light intensity distribution becomes gentler as the defocus increases, but in the case of the comparative example, the light intensity distribution spreads to the non-exposed portion, and the light intensity distribution is high or low (contrast). Lowers the resolution. In the case of the present invention, both the pattern shape and the depth of focus are improved.

Embodiment 5 A diaphragm 113 having a circular through hole 112 as shown in FIG.
A photomask similar to that used in Example 1 using a light source with a bias of 1.0 μm (line pitch 0.2 μm, space width 0.8)
μm). The incident angle of light from the center of the light source was tilted at 16 degrees from the optical axis. According to the simulation, the depth of focus was improved compared to the normal light source.

EXAMPLE 6 Two circular through holes 122A and 12 as shown in FIG.
Using a two-divided light source of the diaphragm 123 having 2B, a photomask similar to that of the first embodiment (line pitch of 1.0 μm and line width of 0.
2 μm, space width 0.8 μm).
The incident angle of light from the center of each through hole (each light source divided into two) was tilted by 16 degrees from the optical axis. According to the simulation, the depth of focus is improved as compared with the normal light source, and the pattern position does not move due to the focus deviation.

Embodiment 7 Four circular through holes 132A to 132D as shown in FIG.
Using the light source of the diaphragm 143 having the photomask 13 having the rectangular repeating translucent pattern 134 shown in FIG.
Patterned with 5. The light from the through hole of the diaphragm 133 is defined as sin ⁻¹ NA ≧ Rθx ≧ sin ⁻¹ (2λ / Px) −sin ⁻¹ NA sin ⁻¹ NA ≧ Rθy ≧ sin ^{− with the} X-direction pitch Px and the Y-direction pitch Py. The incident angles are θx and θy defined by ¹ (2λ / Py) − sin ⁻¹ NA.

Example 8 A photomask similar to that in Example 1 was patterned using the ring-shaped light source of the aperture 143 having the ring through hole 142 shown in FIG. Light incident from the center of the ring width was tilted 16 degrees from the optical axis. According to the simulation, it was found that the depth of focus was improved.

[0036]

As described above, according to the light exposure method of the present invention, the optimum modified illumination system (light source shape) according to the pattern to be obtained is employed, and the advantage of oblique incidence (focus (Improvement of depth and resolution) can be effectively utilized, which contributes to further miniaturization of lithography technology.

[Brief description of drawings]

FIG. 1 is a schematic view of an optical exposure apparatus.

FIG. 2 is a schematic cross-sectional view of a fly-eye lens and a liquid crystal plate diaphragm.

FIG. 3 is a schematic diagram showing diffracted light by vertical light irradiation on a photomask.

FIG. 4 is a partial schematic view of an optical exposure apparatus by vertically irradiating a photomask with light.

FIG. 5 is a partial schematic view of a conventional photoexposure device by obliquely irradiating a photomask.

FIG. 6 is a partial schematic view of a light exposure apparatus by oblique light irradiation according to the present invention.

FIG. 7 is a partial plan view of a line & space pattern.

8A is a plan view of a diaphragm having two linear through holes, and FIG. 8B is a schematic view of the diaphragm.

9 is a graph showing the light intensity in the right angle direction corresponding to the pattern of FIG. 7 on the projection surface when the diaphragm of FIG. 8 (b) is used, and FIG. 9 (a) is the light intensity without defocusing. Is a graph showing the light intensity when the defocus is 0.5 μm, (c) is a graph showing the light intensity when the defocus is 1.0 μm, and (d) Is a graph showing the light intensity when the defocus is 1.5 μm.

FIG. 10 is a plan view of an aperture stop having a round hole through hole.

11 is a graph showing a light intensity distribution in a perpendicular direction according to the pattern of FIG. 7 on the projection surface when the round-hole through-hole diaphragm of FIG. 10 is used, and FIG. It is a graph showing the intensity distribution, (b) is a graph showing the light intensity distribution when the defocus is 0.5μm, (c) is a graph showing the light intensity distribution when the defocus is 1.0μm, And (d) are graphs showing the light intensity distribution when the defocus is 1.5 μm.

FIG. 12 is a plan view of an aperture stop having two linear through holes in parallel and symmetrical positions as a comparative example.

13 is a graph showing a light intensity distribution in a right angle direction corresponding to the pattern of FIG. 7 on a projection surface when the diaphragm of FIG. 12 is used, and FIG. 13A shows a light intensity distribution at a focal position. 3 is a graph, (b) is a graph showing a light intensity distribution when defocus is 0.5 μm, and (c) is defocus 1.0 μ.
It is a graph which shows the light intensity distribution in the case of m, and (d) is a graph which shows the light intensity distribution in the case of defocus of 1.5 μm.

FIG. 14 is a schematic view of an aperture stop provided with one linear through hole, and is a schematic view of each aperture stop having different positions of the linear through holes in (a) to (f).

15A and 15B are graphs of spectral intensities on the pupil according to the pattern of FIG. 7 by a diaphragm in a comparative example, FIG. 15A is a graph by the diaphragm of FIG. 14A, and FIG. 1
4 (b) is a graph with the diaphragm, and (c) is a graph with the diaphragm of FIG. 14 (c).

16 is a graph of spectral intensities on the pupil according to the pattern of FIG. 7 by the diaphragm according to the present invention, FIG.
14C is a graph with the diaphragm of FIG. 14D, FIG. 14B is a graph with the diaphragm of FIG. 14E, and FIG. 14C is a graph with the diaphragm of FIG. 14F.

FIG. 17 is a schematic view of an aperture stop having two linear through holes, and is a schematic diagram of each aperture stop having different positions of the linear through holes in (a) to (e).

FIG. 18 is a graph of the intensity of the spectrum on the pupil according to the pattern of FIG. 7 by the diaphragm in the comparative example, FIG. 18A is a graph by the diaphragm of FIG. 17A, and FIG.
Is a graph by the diaphragm of FIG.

19 is a graph of the spectrum intensity on the pupil according to the pattern of FIG. 7 by the diaphragm according to the present invention, FIG.
17C is a graph of the diaphragm of FIG. 17C, FIG. 17B is a graph of the diaphragm of FIG. 17D, and FIG. 17C is a graph of the diaphragm of FIG.

20 is a graph showing the light intensity in the perpendicular direction according to the pattern of FIG. 7 on the projection surface (focal position and defocus position of 1.0 μm) when the diaphragm of the conventional example in FIG. 14 is used. , (A) is a graph in the case of the diaphragm of FIG. 14 (a), (b) is a graph in the case of the diaphragm of FIG. 14 (b),
14 (c) is a graph in the case of the diaphragm of FIG. 14 (c).

21 is a graph showing the light intensity in the perpendicular direction according to the pattern of FIG. 3 on the projection plane (focal position and defocus position of 1.0 μm) when the diaphragm according to the present invention in FIG. 14 is used. Yes, (a) is a graph in the case of FIG. 14 (d) diaphragm, (b) is a graph in the case of FIG. 14 (e) diaphragm, and (c) is a graph in the case of FIG. 14 (f) diaphragm. It is a graph.

22 is a graph showing the light intensity in the perpendicular direction according to the pattern of FIG. 7 on the projection surface (focal position and defocus position of 1.0 μm) when the diaphragm of the conventional example in FIG. 17 is used. , (A) is a graph in the case of the diaphragm of FIG. 17 (a), and (b) is a graph in the case of the diaphragm of FIG. 17 (b).

23 is a graph showing the light intensity in the perpendicular direction according to the pattern of FIG. 7 on the projection plane (focal position and defocus position of 1.0 μm) when the diaphragm according to the present invention in FIG. 17 is used. 17A is a graph in the case of the diaphragm of FIG. 17C, FIG. 17B is a graph in the case of the diaphragm of FIG. 17D, and FIG. It is a graph.

FIG. 24 is a partial plan view of a line & space pattern having different line widths and space widths.

25 is a graph showing a three-dimensional light intensity distribution (in the case of a focus position) according to the pattern of FIG. 24 on the projection surface when the diaphragm of FIG. 8 (b) is used.

FIG. 26 is a graph showing a light intensity distribution of a three-dimensional light intensity distribution (when defocus is 0.4 μm) according to the pattern of FIG. 24 on the projection surface when the diaphragm of FIG. 8B is used. is there.

27 is a graph showing a light intensity distribution of a three-dimensional light intensity distribution (when defocus is 0.8 μm) according to the pattern of FIG. 24 on the projection surface when the diaphragm of FIG. 8 (b) is used. is there.

28 is a graph showing a light intensity distribution of a three-dimensional light intensity distribution (in the case of a focus position) corresponding to the pattern of FIG. 24 on the projection surface when the round hole through-hole aperture stop of the comparative example is used.

FIG. 29 is a graph showing a light intensity distribution of a three-dimensional light intensity distribution (when defocus is 0.5 μm) according to the pattern of FIG. 24 on the projection surface when the round hole through-hole aperture stop of the comparative example is used. Is.

FIG. 30 is a graph showing a light intensity distribution of a three-dimensional light intensity distribution (in the case of defocus of 1.0 μm) according to the pattern of FIG. Is.

FIG. 31 is a schematic plan view of a diaphragm having one circular through hole.

FIG. 32 is a schematic plan view of a diaphragm having two circular through holes.

FIG. 33 is a schematic plan view of a diaphragm having four circular through holes.

FIG. 34 is a schematic plan view of a photomask having a rectangular repeating pattern.

FIG. 35 is a schematic plan view of a diaphragm having a ring-shaped through hole.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Light source 2 ... Aperture 3 ... Condenser lens 4 ... Deformed illumination system 4 5 ... Photomask (reticle) 5 6 ... Projection lens 6 7 ... Resist film (projection surface) θ ... Incident angle 11 ... Fly's eye lens 12 ... Liquid crystal Plate 21 ... Through hole stripe 22 ... Shading stripe 23 ... Line & space pattern 31, 33 ... Aperture 32, 34 ... Linear through hole 41 ... Aperture 42 ... Round hole 51 ... Aperture 52 ... Linear through hole 61-66 ... Aperture 71-76 ... Linear through hole 81-85 ... Aperture 91-95 ... Linear through hole 101 ... Line (through hole) pattern 102 ... Space (light-shielding) pattern 103 ... Line & space pattern 132A-132D ... Circular through hole 133 ... Aperture 134 ... Rectangular repeating pattern

Claims (7)

[Claims] 1. A method for projecting and exposing a pattern on a photomask onto a resist on a substrate using an exposure device including a modified illumination system including a light source, a diaphragm, and a condenser lens, a photomask, and a projection lens. When the pattern of the photomask is a periodic pattern, the photomask is obliquely illuminated with respect to the optical axis at an angle θ, and sin ⁻¹ NA ≧ Rθ ≧ sin ⁻¹ (2λ / P) − sin ⁻¹ NA In the formula, NA: numerical aperture of projection optical system R: reduction ratio of projection optical system P: line-and-space pitch on projection plane λ: wavelength of projection light 2. A method for projecting and exposing a pattern on a photomask onto a resist on a substrate using an exposure apparatus including a modified illumination system including a light source, a diaphragm, and a condenser lens, a photomask and a projection lens, When the pattern of the photomask is a periodic pattern, one linear light illumination parallel to the pattern at a position apart from the optical axis of the exposure device is used, and the exposure is performed on the optical axis of the photomask. On the other hand, it is an oblique incidence illumination with an angle θ, and sin ^-1 NA ≥ R θ ≥ sin ^-1 (2λ / P) − sin ^-1 NA where NA is the numerical aperture of the projection optical system R is the reduction ratio of the projection optical system P: Line-and-space pitch on the projection surface λ: The light exposure method characterized by the wavelength of the projection light. 3. A method of projecting and exposing a pattern on a photomask onto a resist on a substrate using an exposure apparatus including a modified illumination system including a light source, a diaphragm, and a condenser lens, a photomask and a projection lens, When the pattern of the photomask is a periodic pattern, two linear light illuminations parallel to the pattern at a position apart from the optical axis of the exposure device are used, and the exposure is performed on the optical axis of the photomask. On the other hand, it is an oblique incidence illumination with an angle θ, and sin ^-1 NA ≥ R θ ≥ sin ^-1 (2λ / P) − sin ^-1 NA where NA is the numerical aperture of the projection optical system R is the reduction ratio of the projection optical system P: Line-and-space pitch on the projection surface λ: The light exposure method characterized by the wavelength of the projection light. 4. One circular light illumination is performed at a position away from the optical axis of the exposure apparatus, and an angle of light incident on the photomask from the center of the illumination light is the angle θ. The light exposure method according to claim 1, wherein 5. Illuminating two circular lights at a position distant from and symmetric to the optical axis of the exposure device, the angle of light incident on the photomask from the center of each of the illuminating lights. Is the angle θ. 6. The photomask contains a mixture of a periodic pattern having an X-axis direction pitch Px and a periodic pattern having a Y-axis direction pitch Py, or an X-axis direction pitch Px.
And a pattern having a Y-axis direction pitch Py, four circular light illuminations are performed on the concentric circles and at equal intervals with respect to the optical axis of the exposure apparatus, and the respective circular illuminations are performed from the respective centers of the illumination light. , The angle of light incident on the photomask is an angle θx and an angle θy with respect to the orthogonal X and Y directions, and sin ⁻¹ NA ≧ R θx ≧ sin ⁻¹ (2λ / Px) −sin ⁻¹ NA sin ⁻ An optical exposure method characterized by the following relationship: ¹ NA ≧ R θy ≧ sin ⁻¹ (2λ / Py) −sin ⁻¹ NA. 7. The angle of light incident on the photomask from the center of the ring width of the ring-shaped illumination light is performed by illuminating one ring-shaped light located concentrically with respect to the optical axis of the exposure apparatus. The optical exposure method according to claim 1, wherein is the angle θ.