JPH05335213A - Light exposure method - Google Patents

Abstract

PURPOSE:To provide a method wherein a device pattern (a photomask pattern) is projected and exposed by using a deformed illumination system which is optimum for the pattern regarding a light exposure method in a photolithographic operation for a fine working operation in the manufacture of a semiconductor 4evice. CONSTITUTION:In a method, a pattern on a photomask is projected and exposed on a resist on a substrate by using an aligner which is composed of a deformed illumination system, a photomask and a projection lens. When a line-and-space pattern is used for the pattern on the photomask, the method is constituted so as to use one linear light illumination which is parallel to the pattern in a position at a distance from the optical axis of the aligner (or two linear light illuminations which are symmetric with respect to the center of the optical axis and which are parallel to said pattern). The deformed illumination system is composed of a diaphragm and a condenser lens, and slits 16 are made in the diaphragm 15.

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 largely 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 In order to increase the resolution of light exposure technology,
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), and basically, the 0th order light, the + 1st order light, and the −third order light emitted from the photomask. However, in the modified illumination method, the position of the aperture of the diaphragm is displaced from the optical axis, and the illumination light from the aperture enters the photomask at an angle and exits from the photomask. 0th light and +
An image is formed with two primary light beams. 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 the depth of focus and the resolution are improved overall.

[0004]

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).

[0006]

The above-mentioned object is to provide a light source,
In a method of projecting and exposing a pattern on a photomask onto a resist on a substrate using an exposure apparatus including a diaphragm, a modified illumination system including a condenser lens, a photomask, and a projection lens, the pattern of the photomask is line-and-space. 1 linear light illumination parallel to the pattern at a position distant from the optical axis of the exposure apparatus (or 2 linear light parallel to the pattern that is centrally symmetric about the optical axis). Illumination) is used.

When the pattern of the photomask is a pattern in which the first pattern portion of line and space and the second pattern portion of similar line and space are orthogonal to each other, the photomask is separated from the optical axis of the exposure apparatus. First in position
1st linear light illumination parallel to the pattern part (or
(Two first linear light illuminators parallel to the first pattern portion which are centrosymmetric about the optical axis) and one second linear light illuminator parallel to the second pattern portion at a position apart from the optical axis of the exposure apparatus (Alternatively, two second linear light illuminations parallel to the second pattern portion which are centrally symmetric with respect to the optical axis) are used.

Further, the first linear light and the second linear light become oblique incidence illumination having an angle φ with respect to the optical axis of the photomask, and 2psinφ = λ (where p is a line on the projection plane). It is preferable that the pitch is the set pitch of the AND space pattern, and λ is the wavelength of light. An object of the present invention is to provide a method of projecting and exposing a pattern on a photomask onto a resist on a substrate by using an exposure apparatus including a light source, a diaphragm, a modified illumination system including a condenser lens, a photomask and a projection lens, When the pattern of the photomask is a triangular wave line-and-space pattern with a base angle θ, the first block light illumination in a position parallel to the bottom surface of the triangular wave at a position distant from the optical axis of the exposure apparatus ( Alternatively, two first block light illuminators that are symmetrical about the optical axis and have a positional relationship parallel to the bottom surface of the triangular wave) and a second block light illumination that have a positional relationship perpendicular to the bottom surface of the triangular wave (or center with respect to the optical axis). This is achieved by a light exposure method characterized by using two second block light illuminations which are symmetrical and have a positional relationship perpendicular to the bottom surface of the triangular wave.

Then, the first block light becomes oblique incidence illumination having an angle φ _X with respect to the optical axis of the photomask, and becomes 2p.
sin φ _X = λ sin θ (where p is the set pitch of the line-and-space pattern on the projection surface, and λ is the wavelength of the light), and the second block light is in the photomask. Oblique incidence illumination with an angle φ _Y with respect to the optical axis, and there is a relationship of 2psin φ _Y = λ cos θ.
The ratio of the illumination area of the first block light and the second block light is
sin θ: cos θ is desirable.

[0010]

In the photoexposure method of the present invention, the shape of the illumination light and the oblique incident angle φ corresponding to each photomask pattern are set to the optimum ones, so that both the resolution and the depth of focus are improved in each pattern. The present invention is particularly effective when the line & space pitch of the photomask pattern is close to 1: 1. The line & space pattern is a pattern in which a plurality of linear light-shielding (or transmitting) stripes are arranged in a photomask and a plurality of linear resist stripes are arranged in parallel in a developed resist pattern at regular intervals. Equivalent to.

In the above formula: 2psin φ = λ, the wavelength λ of light is g-line (434 nm), i-line (365 nm) or excimer laser (254 nm of KrF excimer laser).
Is constant, and the incident angle φ is determined according to the pattern pitch width p.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings by way of embodiments and comparative examples of the present invention. FIG. 1 is a schematic view of a light exposure device (stepper), which includes a light source 1 of a mercury lamp (excimer laser) and a diaphragm 2 having a through hole.
And a modified illumination system 4 including a condenser lens 3, a photomask (reticle) 5 having a predetermined pattern, a projection lens 6, and a resist film (projection surface) applied on a substrate.
It is composed of 7. This structure is the same as that of the conventional light exposure apparatus, 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. 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 this case, 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, each single eye is arranged in the desired light source shape (through hole shape). May be. 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, the fly-eye lens 51 (see FIG.
An opening / closing function may be added to each single eye 51a to 51f in 2). For example, the liquid crystal plate 52 is arranged at the exit or entrance of the monocular of the fly-eye lens, and a voltage is applied to the electrode 53 at a place corresponding to the monocular to transmit or block light.

Example 1 A photomask 5 is provided with a light-shielding stripe 1 as shown in FIG.
A line & space pattern 13 composed of 1 and a light-transmissive stripe 12 is formed by a known method. A photomask 5 is obtained by forming a chromium light-shielding film of this pattern on quartz glass. The line & space pitch A is a value corresponding to the set line & space pitch p of the resist pattern to be obtained. In order to obtain the optical illumination according to the present invention, as shown in FIG. 3, two linear through-holes (or light-transmitting) 16 are provided in the diaphragm 15 so as to be point-symmetric with respect to the optical axis of the light exposure apparatus. Parallel to 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 15 is arranged such that these linear through holes 16 are parallel to the line and space pattern 13 of the photomask. Then, the condenser lens 3 illuminates the photomask 5 at an incident angle φ, and the incident angle is an angle with the optical axis of the photoexposure device in the photomask. Next, the 0th-order and + 1st-order diffracted light from the photomask 5 strikes 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. The pattern 13 of the photomask 5 is projected and exposed on the resist film 7 on a substrate such as a semiconductor wafer and developed to obtain a resist pattern.

Light exposure is performed under the following conditions, and the light intensity in a direction perpendicular to the line & space pattern is shown with the projection surface of the resist film as a focal position of the projection lens and a position displaced from it (defocus). 4 (a)-(d). Wavelength of light source (λ) i-line (0.36)
5 μm) Lens aperture (NA) …… 0.5 Coherence factor (σ) …… 0.5 Line and space setting pitch (p) …… 0.35 μm Incident angle (φ) …… 31.4 degrees (Calculated from 2 × 0.35 × sin φ = 0.365) In FIG. 4 (a), the light intensity at the focus position (without defocus) is shown, and in FIG. 4 (b), the defocus is 0.5 μm. 4C shows the light intensity when the defocus is 1.0 μm, and in FIG. 4D, the defocus is 1.5 μm.
The light intensity in m is shown. As can be seen from these FIGS. 4A to 4D, the profiles of light intensity are 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 on the projection surface of the resist film becomes the focus position and defocus position. Then, as shown in FIGS. 5 (a) to 5 (d). Figure 5 (a)
Shows the light intensity at the focus position (no defocus), and in FIG. 5 (b) shows the light intensity when the defocus is 0.5 μm.
FIG. 5C shows the light intensity when the defocus is 1.0 μm, and FIG. 5D shows the light intensity when the defocus is 1.5 μm. As can be seen from FIGS. 5 (a) to 5 (d), the profile of the light intensity increases as the defocus increases.
The level of light intensity (contrast) is reduced, and the resolution is reduced. Naturally, the depth of focus is smaller than in the present invention.

Embodiment 2 Using the photo-exposure device and the photomask 5 of Embodiment 1, the diaphragm is replaced with a diaphragm 17 having a linear through hole 16 shown in FIG. The diaphragm 17 is arranged so that the linear through holes 16 are parallel to the line and space pattern 13 of the photomask.
In this case, the light from the light source 1 passes through the linear through hole 16, enters the condenser lens 3, and the photomask 5 is illuminated with the incident angle φ. Then, the 0th and + 1st order diffracted lights from the photomask 5 hit the projection lens 6, and these diffracted lights are condensed by the lens to form an image of a pattern on the resist film 7 on the projection surface. The pattern 13 of the photomask 5 is projected onto and exposed to light and developed to obtain a resist pattern. In the case of the first embodiment, the photomask 5 is illuminated from both the left and right with respect to the optical axis, whereas in the second embodiment, the photomask 5 is illuminated from one side. Therefore, in comparison with the results of Example 1,
Deterioration of the pattern shape due to defocusing increases. Nevertheless, the depth of focus and the resolution can be increased as compared with the comparative example described above.

Example 3 On the photomask 5, a pattern 23 comprising square light-shielding regions 21 periodically arranged at equal intervals as shown in FIG. 7 and through-hole regions 22 surrounding them is formed by a known method. ..
This pattern 23 is a combination of the line & space pattern of FIG. 2 and the same line & space pattern in the direction perpendicular to this. The line-and-space pitch (the width of the light-shielding region 21 and the mutual distance) A is a value corresponding to the set line-and-space pitch p of the resist pattern to be obtained. In order to provide the optical illumination according to the present invention,
As shown in FIG. 8, two linear through-holes (or light-transmitting) 25 are provided in the diaphragm 24 in the same manner as in Example 1 in point symmetry with respect to the optical axis of the light exposure apparatus and parallel to each other. Further, two linear through holes (or light transmissive) 26 are provided so as to be orthogonal to these linear through holes 25 and are point-symmetric about the optical axis and parallel to each other. The two linear through-holes 25 form the first linear light, and the other pair of linear through-holes 26 form the second linear light, which overlap when rotated 90 degrees about the optical axis. It is a thing. Therefore, four 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. It should be noted that the aperture 24 is formed so that the linear through holes 25 and 26 are in a positional relationship parallel to the photomask line & space pattern 23.
To place. Then, the condenser lens 3 illuminates the photomask 5 at an incident angle φ, and the incident angle is an angle with the optical axis of the photoexposure device in the photomask. Next, the 0th and + 1st order diffracted light from the photomask 5 strikes 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. The pattern 23 of the photomask 5 is projected and exposed on the resist film 7 on a substrate such as a semiconductor wafer and developed to obtain a resist pattern.

In the light exposure apparatus of the first embodiment, light exposure simulation was performed under the following conditions, and the projection surface of the resist film was set to the focal position of the projection lens and the position shifted (defocused) from the projection lens to obtain equal intensity. The three-dimensional light intensity distributions of the lines are shown in FIGS. Wavelength of light source (λ) i-line (0.36)
5 μm) Lens aperture (NA) …… 0.5 Coherence factor (σ) …… 0.5 Line and space setting pitch (p) …… 0.35 μm Incident angle (φ) …… 31.4 degrees (Calculated from 2 × 0.35 × sin φ = 0.365) FIG. 9A shows the light intensity distribution at the focal position (no defocus), and in FIG. 9B, the defocus is 0. The light intensity distribution at 2 μm is shown. In FIG. 9C, the defocus is 0.4 μm.
The light intensity distribution at m is shown, and in FIG.
FIG. 9E shows a light intensity distribution at 0.6 μm, FIG. 9E shows a light intensity distribution at a defocus of 0.8 μm, and FIG.
(F) shows the light intensity distribution when the defocus is 1.0 μm. As can be seen from FIGS. 9A to 9F, the shapes of the light intensity distributions are 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 a focus position and defocus. The position is as shown in FIGS. Figure 1
0 (a) shows the light intensity distribution at the focus position (no defocus), FIG. 10 (b) shows the light intensity distribution at the defocus of 0.2 μm, and FIG. 10 (c) shows the focus. Deviation is 0.4
FIG. 10 (d) shows the light intensity distribution at a defocus of 0.6 μm, and FIG. 10 (e) shows the light intensity distribution at a defocus of 0.8 μm. , And FIG. 10 (f) show the light intensity distribution when the defocus is 1.0 μm. As can be seen from these FIGS. 10A to 10F, as the defocus of the light intensity distribution becomes larger, the intensity difference becomes gentler and spreads to the non-exposed portion, and the height (contrast) of the light intensity distribution becomes smaller. , The resolution drops. Naturally, the depth of focus is smaller than in the present invention.

Embodiment 4 Using the light exposure apparatus and the photomask 5 in Embodiment 3, the diaphragm is replaced by two diaphragms 27 with one linear through hole 25 and 26 shown in FIG. Orthogonal linear through holes 25,
The diaphragm 27 is arranged so that 26 is in a positional relationship parallel to the pattern 23 of the square light-shielding regions 21 (two sets of lines and spaces) periodically arranged at regular intervals in the photomask. In this case, the light from the light source 1 is transmitted through the linear through holes 25, 2
After passing through 6, the light enters the condenser lens 3, and the incident angle φ
The photomask 5 is illuminated with light. Then, the 0th and + 1st order diffracted lights from the photomask 5 hit the projection lens 6, and these diffracted lights are condensed by the lens to form an image of a pattern on the resist film 7 on the projection surface. The pattern 13 of the photomask 5 is projected onto and exposed to light and developed to obtain a resist pattern. In the case of the third embodiment, the photomask 5 is illuminated from both the left and right with respect to the optical axis, whereas in the fourth embodiment, the photomask 5 is illuminated from one side. Therefore, as compared with the result of the third embodiment, the deterioration of the pattern shape due to the defocus is increased. Nevertheless, the depth of focus and the resolution can be increased as compared with the comparative example described above.

The linear light in Examples 1 to 4 is the light that has passed through the linear through hole whose width of the through hole (slit) in the diaphragm is selected from the range of 5 to 10 mm. (That is, σ) becomes smaller, the exposure time becomes longer, and if it is too thick, the component that becomes noise will pass through, and the effect will be weakened. It is preferably 5 to 10 mm. Example 5 On the photomask 5, a line & space pattern 33 consisting of a triangular wave-shaped light-shielding stripe 31 having a bottom angle θ and a through-hole stripe 32 as shown in FIG. 12 is formed by a known method. The line & space pitch A is a value corresponding to the set line & space pitch p of the resist pattern to be obtained. In order to obtain the optical illumination according to the present invention, as shown in FIG. 13, a first block through hole 35 of the same shape is formed in the diaphragm 34 at a position distant from the optical axis of the light exposure apparatus and is point-symmetric about the optical axis. Two pieces are provided in parallel with the longitudinal direction of the stripe, and two second block through holes 36 of the same shape are provided in positions distant from the optical axis of the light exposure device, and are point-symmetric about the optical axis and perpendicular to the longitudinal direction of the stripe. Provide (provide a total of 4 through holes). The two block through holes 35 form the first block light, and the other set of block through holes 36 form the second block light. The areas of these through holes are the first block light and the second block light. And the illumination area ratio is sin θ: co
It is set to be s θ. The shape of each block through hole is any one of a rectangle, a circle, an ellipse, a rhombus, a triangle, and the like, which is a block shape that secures a through hole area. Therefore, four through holes are formed in the light blocking diaphragm, and the light from the light source 1 passes through these through holes and enters the condenser lens 3. Then, light illumination from the condenser lens 3 to the photomask 5 is performed by the block through hole
Light is incident at an incident angle φ _X and light in the block through hole 36 is incident at an incident angle φ _Y , and these incident angles are angles with the optical axis of the light exposure device in the photomask. The incident angle φ _X has a relation of 2 psin φ _X = λsin θ (where p is the set pitch of the line-and-space pattern, λ is the wavelength of light), and the incident angle φ _Y is 2
Set to the relationship of psin φ _Y = λ cos θ. Next, the 0th and + 1st order diffracted light from the photomask 5 strikes 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. The pattern 33 of the photomask 5 is projected and exposed on the resist film 7 on a substrate such as a semiconductor wafer and developed to obtain a resist pattern.

Therefore, a triangular wave stripe pattern 38 used in the active region of the DRAM as shown in FIG.
In this case, as the block through holes 39 and 40 of the photomask as shown in FIG. 15, the light exposure simulation is performed under the following conditions, and the projection surface is at the focal position of the projection lens and the position (shifted position) deviated from the focal position. As shown in FIGS. 16A to 16C and 17A to 17D, three-dimensional light intensity distributions are obtained with isointensity lines.

Setting pitch of line & space of triangular wave stripe pattern 38 (p) 0.35 μm Base angle of triangular wave stripe (θ) 30 degrees Wavelength of light source (λ) i line (0.36)
5 μm) Lens aperture (NA) …… 0.5 Coherence factor (σ) …… 0.5 Incident angle of block through-hole 39 (φ _X ) …… 74.8 degrees Incident angle of block through-hole 40 ( φ _Y ) …… 26.8 degrees Area ratio of block through hole 39 and block through hole 39 ……
0.5: 0.866 FIG. 16A shows the light intensity distribution at the focus position (no defocus), and in FIG. 16B, the defocus is 0.2 μm.
16C shows the light intensity distribution, and in FIG.
17A shows the light intensity distribution at 0.4 μm, and FIG. 17A shows the light intensity distribution at a defocus of 0.6 μm.
Shows the light intensity distribution when the defocus is 0.8 μm.
7C shows the light intensity distribution when the defocus is 1.0 μm, and FIG. 17D shows the light intensity distribution when the defocus is 1.2 μm. As can be seen from FIGS. 16 and 17, the shape of the light intensity distribution is almost the same up to the defocus of 1.0 μm, and the depth of focus is large.

As a comparative example, under the same light exposure apparatus conditions, when light exposure is performed using a diaphragm having a conventional round hole 41 shown in FIG. 18 (σ = 0.5), the light intensity distribution on the projection surface is shown. Are as shown in FIGS. 19 (a) to (c) and FIGS. 20 (a) to (d) at the focus position and the defocus position. FIG. 19
19A shows the light intensity distribution at the focus position (without defocus), FIG. 19B shows the light intensity distribution when the defocus is 0.2 μm, and FIG. 19C shows the defocus. Is 0.4μ
20A shows a light intensity distribution at m, FIG. 20A shows a light intensity distribution at a defocus of 0.6 μm, and FIG.
FIG. 20 shows the light intensity distribution when the defocus is 0.8 μm.
20C shows the light intensity distribution when the defocus is 1.0 μm, and FIG. 20D shows the light intensity distribution when the defocus is 1.2 μm. As can be seen from FIGS. 19 and 20, as the defocus of the light intensity distribution becomes larger, the intensity difference becomes gentler and spreads to the non-exposed portion, and the height (contrast) of the light intensity distribution becomes smaller and the resolution is lowered. To do. Naturally, the depth of focus is smaller than in the present invention.

Sixth Embodiment Using the light exposure apparatus and the photomask 5 in the fifth embodiment, the diaphragm is replaced with the diaphragm 45 shown in FIG. The diaphragm 45 is arranged so that the block through hole 35 is in a positional relationship parallel to the bottom surface of the triangular wave of the triangular wave stripe and the block through hole 36 is in a positional relationship perpendicular to the bottom surface. In this case, the light from the light source 1 passes through the block through holes 35 and 36 and enters the condenser lens 3, and the photomask 5 is illuminated with the incident angle φ _X and the incident angle φ _Y. Then, the 0th and + 1st order diffracted lights from the photomask 5 hit the projection lens 6, and these diffracted lights are condensed by the lens to form an image of a pattern on the resist film 7 on the projection surface.
The pattern 33 of the photomask 5 is projected and exposed, and developed to obtain a resist pattern. In the case of the fifth embodiment, the photomask 5 is illuminated from both the left and right sides with respect to the optical axis, whereas in the sixth embodiment, the illumination is from one side. Therefore, as compared with the result of the fifth embodiment, the deterioration of the pattern shape due to the defocus is increased.
Nevertheless, the depth of focus and the resolution can be increased as compared with the comparative example described above.

[0027]

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 adopted, 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 for modified illumination (oblique incidence illumination).

FIG. 2 is a partial plan view of a line & space pattern.

FIG. 3 is a plan view of an aperture stop having two linear through holes.

4 is a graph showing the light intensity in the right angle direction corresponding to the pattern of FIG. 2 on the projection surface when the diaphragm of FIG. 3 is used, and FIG. 4A is a graph showing the light intensity without defocusing. (B) 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 the defocus. 1.5
It is a graph which shows the light intensity in the case of μm.

5 is a graph showing a light intensity in a right angle direction corresponding to the pattern of FIG. 2 on a projection surface when a conventional round hole diaphragm is used, and (a) shows a light intensity without defocusing. 3 is a graph, (b) 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 the focus Gap
It is a graph which shows the light intensity in case of 1.5 micrometers.

FIG. 6 is a plan view of an aperture stop having one linear through hole.

FIG. 7 is a partial plan view of a combination pattern of a set of line and space patterns having an orthogonal relationship.

FIG. 8 is a plan view of a diaphragm provided with two sets of parallel linear through holes arranged orthogonally.

9 is a graph showing a three-dimensional light intensity distribution according to the pattern of FIG. 7 on the projection surface when the diaphragm of FIG. 8 is used, and FIG. 9A shows the light intensity distribution at the focus position. 3B is a graph, (b) is a graph showing a light intensity distribution when the defocus is 0.2 μm, (c) is a graph showing a light intensity distribution when the defocus is 0.4 μm, and (d) is Defocus
6 is a graph showing a light intensity distribution in the case of 0.6 μm,
(E) is a graph showing the light intensity distribution when the defocus is 0.8 μm, and (f) is a graph showing the light intensity distribution when the defocus is 1.0 μm.

FIG. 10 is a graph showing a three-dimensional light intensity distribution corresponding to the pattern of FIG. 7 on a projection surface when a conventional round hole diaphragm is used, and (a) shows a light intensity distribution at a focus position. FIG. 4B is a graph showing the light intensity distribution when the defocus is 0.2 μm, and FIG.
It is a graph showing the light intensity distribution in the case of m, (d) is a graph showing the light intensity distribution in the case of defocus of 0.6μm, (e) is the light intensity distribution in the case of defocus of 0.8μm 6A and 6B are graphs showing the light intensity distribution in the case where the defocus is 1.0 μm.

FIG. 11 is a plan view of an aperture stop provided with orthogonal linear through holes.

FIG. 12 is a partial plan view of a triangular wave-shaped line & space pattern.

FIG. 13 is a plan view of an aperture stop including two pairs of block through holes separated from the optical axis.

FIG. 14 is a partial plan view of a triangular wave-shaped line & space pattern used in an active region of a DRAM.

FIG. 15 is a plan view of a diaphragm having two pairs of rectangular through holes separated from the optical axis.

16 is a graph showing a three-dimensional light intensity distribution according to the pattern of FIG. 14 on the projection surface when the diaphragm of FIG. 15 is used, and FIG. 16 (a) shows the light intensity distribution at the focus position. 3 is a graph, (b) is a graph showing the light intensity distribution when the defocus is 0.2 μm, and (c) is the defocus.
7 is a graph showing a light intensity distribution in the case of 0.4 μm.

17 is a graph showing a three-dimensional light intensity distribution according to the pattern of FIG. 14 on the projection surface when the diaphragm of FIG. 15 is used, and FIG. 17 (a) is a light intensity when defocus is 0.6 μm. 3 is a graph showing a distribution, (b) is a graph showing a light intensity distribution when a defocus is 0.8 μm, (c) is a graph showing a light intensity distribution when a defocus is 1.0 μm, and (D) is a graph showing the light intensity distribution when the defocus is 1.2 μm.

FIG. 18 is a plan view of a diaphragm having a through hole corresponding to a conventional round hole.

19 is a graph showing a three-dimensional light intensity distribution corresponding to the pattern of FIG. 14 on the projection surface when the conventional diaphragm of FIG. 19 is used, and FIG. 19 (a) is a light intensity distribution in the case of a focus position. 2B is a graph showing the light intensity distribution when the defocus is 0.2 μm, and FIG. 7C is a graph showing the light intensity distribution when the defocus is 0.4 μm.

20 is a graph showing a three-dimensional light intensity distribution according to the pattern of FIG. 14 on the projection surface when the conventional diaphragm of FIG. 19 is used, and FIG. 20 (a) shows a case of defocus of 0.6 μm. It is a graph showing the light intensity distribution, and (b) is a defocus of 0.8.
FIG. 3 is a graph showing a light intensity distribution in the case of μm, (c) is a graph showing a light intensity distribution in the case of defocus of 1.0 μm, and (d) is a light intensity distribution in the case of defocus of 1.2 μm. It is a graph which shows.

FIG. 21 is a plan view of an aperture stop having two sets of block through holes separated from the optical axis.

FIG. 22 is a schematic cross-sectional view of a fly-eye lens and a liquid crystal plate diaphragm.

[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) φ ... Incident angle 11 ... Shading stripe 12 ... Through-hole stripe 13 ... Line & space pattern 15, 17 ... Aperture 16 ... Linear through hole 21 ... Light blocking area 22 ... Through hole area 23 ... Pattern 24, 27 ... Aperture 25, 26 ... Linear through hole 32 ... Triangular wave light blocking stripe 32 ... Triangular wave through hole stripe 33 ... Line & space pattern 34, 45 ... Aperture 35, 36 ... Block through hole 38 ... Triangular wave stripe pattern in DRAM 51 ... Fly's eye lens 52 ... Liquid crystal plate

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // G02B 26/00 9226-2K

Claims (10)

[Claims] 1. 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 line-and-space pattern, one linear light illumination parallel to the pattern at a position apart from the optical axis of the exposure device is used. .. 2. 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 line-and-space pattern, two linear light illuminators parallel to the pattern symmetrical about the center at a position apart from the optical axis of the exposure apparatus are used. Exposure method. 3. The light is oblique incidence illumination having an angle φ with respect to the optical axis of the photomask, and 2psin φ = λ
3. The method according to claim 1 or 2, wherein p is a set pitch of a line-and-space pattern on a projection surface and λ is a wavelength of light. 4. 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, The photomask pattern has a similar line and space second pattern portion to a line and space second pattern portion.
When the pattern part is orthogonal to the pattern,
One first linear light illumination parallel to the first pattern portion at a position away from the optical axis of the exposure device, and one parallel linear light illumination at a position away from the optical axis of the exposure device to the second pattern portion. 2. A light exposure method characterized by using the second linear light illumination of. 5. 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, The photomask pattern has a similar line and space second pattern portion to a line and space second pattern portion.
When the pattern part is orthogonal to the pattern,
Two first linear light illuminators parallel to the first pattern portion that are centrally symmetric at a position away from the optical axis of the exposure apparatus, and the second linearly symmetric second at a position away from the optical axis of the exposure apparatus.
An optical exposure method characterized by using two second linear light illuminations parallel to a pattern portion. 6. The oblique incidence illumination in which the first linear light and the second linear light form an angle φ with respect to the optical axis of the photomask is 2 psin φ = λ (where p is a projection plane). Is a set pitch of the line-and-space pattern, and λ is a wavelength of light).
Alternatively, the method according to claim 5. 7. 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 triangular wave line-and-space pattern having a base angle θ, the first block light having a positional relationship parallel to the bottom surface of the triangular wave at a position away from the optical axis of the exposure apparatus. An optical exposure method characterized by using illumination and second block light illumination in a positional relationship perpendicular to the bottom surface of the triangular wave. 8. 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 triangular wave line-and-space pattern having a base angle θ, a positional relationship of a center symmetry at a position apart from the optical axis of the exposure apparatus and parallel to the bottom surface of the triangular wave is provided. A first block light illumination and two second block light illuminations which are centrally symmetric with respect to the optical axis and have a positional relationship perpendicular to the bottom surface of the triangular wave. 9. The method according to claim 7, wherein the modified illumination system comprises a light source, a diaphragm, and a condenser lens. 10. The oblique incidence illumination in which the first block light forms an angle φ _X with respect to the optical axis of the photomask,
2psin φ _X = λsin θ (where p is the set pitch of the line-and-space pattern in the resist, and λ is the wavelength of light), and the second block light is the photomask. Is an oblique incidence illumination with an angle φ _Y with respect to the optical axis of 2 psin φ _Y = λ cos θ, and the ratio of the illumination area of the first block light to the second block light is sin θ: 9. The method of claim 7 or claim 8 wherein cos θ.