JP2848425B2 - Light exposure method - Google Patents

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 the like, and more particularly, to a light exposure method in photolithography.
Advances in high integration and microfabrication of semiconductor devices such as VLSIs are heavily dependent on lithography technology improvements. Among them, optical lithography using light is suitable for mass production and is also used for economic reasons. R & D for further improvement is 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 aperture (NA) of the lens and shorten the wavelength of the light source. On the other hand, the depth of focus decreases as the NA increases. Accordingly, a deformed illumination method (oblique incidence illumination method) for improving the limit resolution and the depth of focus has recently attracted attention (see, for example, Nikkei Microdevices, No. 82, April 1992, pp. 28-37). .

[0003] As a hole shape in a stop (aperture) in the modified illumination method, a hole shape having an annular zone or a hole shape having four point-symmetric holes is known. In the conventional illumination method, illumination light to a photomask (reticle) is vertically incident from a circular hole coinciding with the optical axis of an exposure apparatus, and is basically a 0th-order light, a + 1st-order light and a −th-order light emitted from the photomask. However, in the modified illumination method, the position of the hole of the aperture is shifted from the optical axis, and the illumination light from the hole is obliquely incident on the photomask and exits from the photomask. 0th order light and +
An image is formed by two light beams of primary light. At the focal position, the conventional illumination method has higher contrast, but at the defocus position, the modified illumination method has higher contrast, and the depth of focus and the resolution are improved overall.

[0004]

In the conventional modified illumination method, the pattern of the photomask is applied to the resist with the above-described almighty type aperture hole only for a simple line and (&) space pattern. Projection exposure. Therefore, the illumination system is not adapted to the individual pattern shapes, 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 projecting and exposing a device pattern (photomask pattern) using a modified illumination system most suitable for the device pattern (photomask pattern).

[0006]

SUMMARY OF THE INVENTION The above object is achieved by a light source,
A method of projecting and exposing a pattern of the photomask onto a resist on a substrate using an aperture, a modified illumination system such as a condenser lens, an exposure apparatus including a photomask and a projection lens, wherein the pattern of the photomask is line and space. , One linear light illumination parallel to the pattern at a position distant from the optical axis of the exposure apparatus (or two linear lights parallel to the pattern symmetrical with respect to the optical axis) (Lighting).

When the pattern of the photomask is a pattern in which a first line-and-space pattern portion and a similar second line-and-space pattern portion are orthogonal to each other, the photomask is separated from the optical axis of the exposure apparatus. First in position
One first linear light illumination parallel to the pattern portion (or
Two first linear light illuminations parallel to the first pattern portion symmetrical with respect to the optical axis) and one second linear light illumination parallel to the second pattern portion at a position distant from the optical axis of the exposure apparatus. (Alternatively, two second linear light illuminations parallel to the second pattern portion symmetrical about the optical axis) are achieved by a light exposure method.

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 2psin φ = λ (where p is a line on the projection surface) Is a set pitch of an AND space pattern, and λ is a wavelength of light). An object of the present invention is to provide a method for projecting and exposing a pattern on a photomask to a resist on a substrate by using a light source, an aperture, a modified illumination system such as a condenser lens, and an exposure apparatus including 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 away from the optical axis of the exposure apparatus. Alternatively, two first block light illuminations that are symmetrical about the optical axis and have a positional relationship parallel to the bottom surface with a triangular wave) and a second block light illumination that has a positional relationship perpendicular to the bottom surface with a triangular wave (or a center with respect to the optical axis). This is achieved by a light exposure method characterized by using two symmetrical, 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 2p
sin φ _x = λ sin θ (where p is the set pitch of the line and space pattern on the projection plane, and λ is the wavelength of light), and the second block light is It becomes oblique incidence illumination with an angle φ _Y with respect to the optical axis, and has a relationship of 2 psin φ _Y = λ cos θ.
The ratio of the illumination area between the first block light and the second block light is
sin θ: cos θ is desirable.

[0010]

According to the light exposure method of the present invention, the illumination light shape and the oblique incident angle φ corresponding to the individual photomask patterns are set to be optimum, so that the resolution and the depth of focus can be improved for each pattern. The present invention is particularly effective when the line and 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 transmission) stripes are arranged in a photomask, and a plurality of linear resist stripes are arranged in parallel at regular intervals in a developed resist pattern. Is equivalent to

In the above equation: 2p sin φ = λ, the light wavelength λ is g-line (434 nm), i-line (365 nm) or excimer laser (254 nm of KrF excimer laser).
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 below in detail with reference to the accompanying drawings with reference to embodiments and comparative examples of the present invention. FIG. 1 is a schematic view of a light exposure apparatus (stepper). A light source 1 of a mercury lamp (excimer laser) and an aperture 2 having a through hole are shown.
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 the substrate
7. This configuration is the same as that of the conventional light exposure apparatus, and in the present invention, the through hole shape of the diaphragm 2 is different from the conventional one, which is a structural difference. Note that, similarly to the conventional light exposure apparatus, a compound-eye condensing lens (fly-eye lens) may be arranged between the light source and the stop.

In this case, the shape of the light source is defined by the shape of the aperture of the stop, but each single eye is arranged in the shape of the target light source (the shape of the aperture) using a fly-eye lens. You may. When the shape of the light source is changed in accordance with the intended use, when a stop is used, the stop may be replaced with a stop having a different through-hole shape. Alternatively, the fly-eye lens 51 (FIG. 2)
The opening / closing function may be added to each of the monoculars 51a to 51f in 2). For example, a 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 corresponding to the monocular to transmit or block light.

Embodiment 1 A light-shielding stripe 1 as shown in FIG.
A line-and-space pattern 13 composed of 1 and a light-transmitting stripe 12 is formed by a known method. A photomask 5 is formed by forming a chrome light-shielding film having this pattern on quartz glass. The line & space pitch A is a value corresponding to the line & space setting pitch p of the resist pattern to be obtained. In order to obtain the light illumination according to the present invention, as shown in FIG. 3, two linear through-holes (or light-transmitting holes) 16 are provided in the stop 15 point-symmetrically with respect to the optical axis of the light exposure apparatus. It is provided in parallel with. Therefore, two slits are formed in the light-blocking diaphragm, and light from the light source 1 passes through these slits and enters the condenser lens 3. The aperture 15 is arranged so that these linear through holes 16 are parallel to the line & space pattern 13 of the photomask. Then, light illumination is performed from the condenser lens 3 to the photomask 5 at an incident angle φ, and the incident angle is an angle of the photomask with the optical axis of the light exposure apparatus. Next, the 0th-order and + 1st-order diffracted lights from the photomask 5 strike 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 and exposed on the resist film 7 on a substrate such as a semiconductor wafer or the like, and can be 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 plotted assuming that the projection surface of the resist film is the focal position of the projection lens and a position shifted (defocused) therefrom. 4 (a) to (d). Light source wavelength (λ) i-line (0.36
5 μm) Lens aperture (NA) 0.5 Coherence factor (σ) 0.5 Set pitch of line and space (p) 0.35 μm Incident angle (φ) 31.4 degrees (Calculated from 2 × 0.35 × sin φ = 0.365) FIG. 4A shows the light intensity at the focal position (without defocus), and FIG. 4B shows that the defocus is 0.5 μm. 4 (c) shows the light intensity when the defocus is 1.0 μm, and FIG. 4 (d) shows the light intensity when the defocus is 1.5 μm.
The light intensity at m is shown. As can be seen from FIGS. 4A to 4D, the profiles of the light intensity are almost the same, and the depth of focus is large.

As a comparative example, when light exposure is performed using a conventional round hole stop (σ = 0.5) using the same light exposure apparatus, the light intensity on the projection surface of the resist film becomes the focal position and the defocus position. 5 (a) to 5 (d). FIG. 5 (a)
Shows the light intensity at the focal position (no defocus), and FIG. 5B 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. 5A to 5D, the light intensity profile increases as the defocus increases.
The level of light intensity (contrast) decreases, and the resolution decreases. Naturally, the depth of focus is smaller than in the case of the present invention.

Embodiment 2 Using the light exposure apparatus and the photomask 5 in Embodiment 1, the aperture is replaced by a single aperture 17 with a linear through hole 16 shown in FIG. The aperture 17 is arranged so that the linear through hole 16 is parallel to the line & space pattern 13 of the photomask.
In this case, light from the light source 1 passes through the linear through-hole 16 and is incident on the condenser lens 3, and light illumination is performed on the photomask 5 at an incident angle φ. Then, the 0th-order and + 1st-order diffracted lights from the photomask 5 impinge on 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 and exposed 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 illumination is performed from one side. Therefore, compared with the result of Example 1,
Deterioration of the pattern shape due to defocus increases. Nevertheless, compared to the above-described comparative example, the depth of focus and the resolution can be increased.

Embodiment 3 As shown in FIG. 7, a pattern 23 consisting of square light-shielding areas 21 periodically arranged at regular intervals and a through-hole area 22 surrounding these areas is formed on the photomask 5 by a known method. .
The pattern 23 is a combination of the line & space pattern of FIG. 2 and the same line & space pattern in the direction perpendicular to the line & space pattern. The pitch A of the line and space (the width of the light-shielding area 21 and the interval between them) A is a value corresponding to the set pitch p of the line and space of the resist pattern to be obtained. In order to make the light illumination according to the present invention,
As shown in FIG. 8, two linear through-holes (or light-transmitting holes) 25 are provided in the stop 24 in a point-symmetric manner with respect to the optical axis of the light exposure apparatus and parallel to each other, as in the first embodiment. Further, orthogonal to the linear through holes 25, two linear through holes (or translucent holes) 26 are provided point-symmetrically with respect to the optical axis and parallel to each other. Two linear through-holes 25 constitute a first linear light, and another set of linear through-holes 26 constitute a second linear light, which overlaps when rotated by 90 degrees about the optical axis. Things. Therefore, four slits are formed in the light-blocking aperture, and light from the light source 1 passes through these slits and enters the condenser lens 3. The apertures 24 are arranged so that the linear through holes 25 and 26 have a positional relationship parallel to the line & space pattern 23 of the photomask.
Place. Then, light illumination is performed from the condenser lens 3 to the photomask 5 at an incident angle φ, and the incident angle is an angle of the photomask with the optical axis of the light exposure apparatus. Next, the 0th-order and + 1st-order diffracted lights from the photomask 5 strike 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 23 of the photomask 5 is projected and exposed on the resist film 7 on a substrate such as a semiconductor wafer or the like, and can be 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 defined as the focal position of the projection lens and a position shifted (out of focus) from the projection lens. 9A to 9F show three-dimensional light intensity distributions by lines. Light source wavelength (λ) i-line (0.36
5 μm) Lens aperture (NA) 0.5 Coherence factor (σ) 0.5 Set pitch of line and space (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 FIG. FIG. 9C shows the light intensity distribution at 2 μm, and FIG.
FIG. 9D shows the light intensity distribution at m.
FIG. 9E shows the light intensity distribution at 0.6 μm, and FIG. 9E shows the light intensity distribution at a defocus of 0.8 μm.
(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 light exposure is performed using a conventional round hole stop (σ = 0.5) with the same light exposure apparatus, the light intensity distribution on the projection surface of the resist film becomes a focal position and a defocus. The positions are as shown in FIGS. FIG.
0 (a) shows the light intensity distribution at the focal position (no defocus), FIG. 10 (b) shows the light intensity distribution when the defocus is 0.2 μm, and FIG. The gap is 0.4
FIG. 10D shows the light intensity distribution when the defocus is 0.6 μm, and FIG. 10E shows the light intensity distribution when the defocus is 0.8 μm. , And FIG. 10 (f) shows the light intensity distribution when the defocus is 1.0 μm. As can be seen from FIGS. 10A to 10F, as the defocus increases, the difference in intensity of the light intensity distribution becomes gentler and spreads to the non-exposed portion, and the level (contrast) of the light intensity distribution decreases. , The resolution is reduced. Naturally, the depth of focus is smaller than in the case of the present invention.

Embodiment 4 Using the light exposure apparatus and the photomask 5 of Embodiment 3, the apertures are replaced by two apertures 27 each having one linear through hole 25 and 26 shown in FIG. Orthogonal linear through holes 25,
The stop 27 is arranged so that the pattern 26 is in parallel with the pattern 23 of the square light-blocking areas 21 (two sets of lines and spaces) periodically arranged at regular intervals on the photomask. In this case, the light from the light source 1 is
6 and enters the condenser lens 3 at an incident angle φ
Then, light illumination is performed on the photomask 5. Then, the 0th-order and + 1st-order diffracted lights from the photomask 5 impinge on 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 and exposed 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 illumination is performed from one side. Therefore, as compared with the result of the third embodiment, the deterioration of the pattern shape due to the defocus increases. Nevertheless, compared to the above-described comparative example, the depth of focus and the resolution can be increased.

The linear light in Examples 1 to 4 is light that has passed through a linear through hole whose slit has a width selected from a range of 5 to 10 mm at the diaphragm. (That is, σ) becomes small, and the exposure time becomes long. If the thickness is too large, a component that becomes noise passes through, and the effect is weakened. Preferably it is 5 to 10 mm. Example 5 A line & space pattern 33 composed of a triangular wave-shaped light-shielding stripe 31 and a through-hole stripe 32 having a base angle θ as shown in FIG. 12 is formed on the photomask 5 by a known method. The line & space pitch A is a value corresponding to the line & space setting pitch p of the resist pattern to be obtained. As shown in FIG. 13, a first block through-hole 35 having the same shape as the stop 34 is provided at a position distant from the optical axis of the light exposure apparatus and point-symmetrically with respect to the optical axis, as shown in FIG. Two pieces of second block through holes 36 having the same shape are provided in parallel with the longitudinal direction of the stripe, and two pieces of the second block through holes 36 are point-symmetric about the optical axis and perpendicular to the longitudinal direction of the stripe at a position away from the optical axis of the light exposure apparatus. (Total of four through holes are provided). The two block through-holes 35 constitute a first block light, and the other set of block through-holes 36 constitute a second block light. The areas of these through-holes are the first block light and the second block light. And the ratio of the illumination area is sin θ: co
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 in which a through hole area is secured. Therefore, four through-holes are formed in the light-blocking aperture, and 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 applied to the block through hole 35.
At the incident angle φ _X and the light at the block through hole 36 at the incident angle φ _Y , which are the angles of the photomask with the optical axis of the light exposure apparatus. The incident angle φ _X has a relationship of 2 p sin φ _X = λ sin θ (where p is the set pitch of the line and space pattern and λ is the wavelength of light), and the incident angle φ _Y is 2
psin φ _Y = λ cos θ is set. Next, the 0th-order and + 1st-order diffracted lights from the photomask 5 strike 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 on the resist film 7 on a substrate such as a semiconductor wafer or the like, and can be developed to obtain a resist pattern.

Therefore, a triangular-wave stripe pattern 38 used for the active region of the DRAM as shown in FIG.
In the case of (1), the light exposure simulation was performed under the following conditions as the block through holes 39 and 40 of the photomask as shown in FIG. 15 to shift the projection plane to the focal position of the projection lens and the position shifted (defocused) therefrom. 16 (a) to 16 (c) and FIGS. 17 (a) to 17 (d) show three-dimensional light intensity distributions with isointensity lines.

Set pitch of line and space of triangular wave stripe pattern 38 (p) 0.35 μm Base angle of triangular wave stripe (θ) 30 degrees Light source wavelength (λ) i-line (0.36)
5 μm) Lens aperture (NA) 0.5 Coherence factor (σ) 0.5 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 between block through-hole 39 and block through-hole 39.
0.5: 0.866 FIG. 16A shows the light intensity distribution at the focal position (no defocus), and FIG. 16B shows that the defocus is 0.2 μm.
FIG. 16C shows the light intensity distribution, and in FIG.
FIG. 17A shows a light intensity distribution at 0.4 μm, and FIG. 17A shows a light intensity distribution at a defocus of 0.6 μm.
FIG. 1 shows the light intensity distribution when the defocus is 0.8 μm.
7 (c) shows the light intensity distribution when the focus shift is 1.0 μm, and FIG. 17 (d) shows the light intensity distribution when the focus shift is 1.2 μm. As can be seen from FIGS. 16 and 17, the shape of the light intensity distribution is almost the same and the depth of focus is large up to a defocus of 1.0 μm.

As a comparative example, when light exposure is performed using the conventional stop (σ = 0.5) having a round hole 41 shown in FIG. 18 under the same light exposure apparatus conditions, the light intensity distribution on the projection surface is obtained. 19 (a) to 19 (c) and FIGS. 20 (a) to 20 (d) at the focus position and the defocus position. FIG.
19A shows the light intensity distribution at the focal position (no defocus), FIG. 19B shows the light intensity distribution when the defocus is 0.2 μm, and FIG. Is 0.4μ
20 (a) shows the light intensity distribution when the defocus is 0.6 μm, and FIG. 20 (b)
FIG. 20 shows the light intensity distribution when the defocus is 0.8 μm.
FIG. 20C shows the light intensity distribution when the focus shift is 1.0 μm, and FIG. 20D shows the light intensity distribution when the focus shift is 1.2 μm. As can be seen from FIGS. 19 and 20, as the defocus increases, the difference in intensity of the light intensity becomes gentler and spreads to the non-exposed portion, and the level of the light intensity distribution (contrast) decreases, and the resolution decreases. I do. Naturally, the depth of focus is smaller than in the case of the present invention.

Embodiment 6 Using the light exposure apparatus and the photomask 5 of Embodiment 5, the apertures are replaced with apertures 45 each having one block through hole 35 and 36 shown in FIG. The aperture 45 is arranged such 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 is passed through the block Toruana 35, enters the condenser lens 3, the light illumination to the photo mask 5 is performed at an incident angle phi _X a and the incidence angle phi _Y. Then, the 0th-order and + 1st-order diffracted lights from the photomask 5 impinge on 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 with respect to the optical axis, whereas in the sixth embodiment, the illumination is performed from one side. Therefore, as compared with the result of the fifth embodiment, the deterioration of the pattern shape due to the defocus increases.
Nevertheless, compared to the above-described comparative example, the depth of focus and the resolution can be increased.

[0027]

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

[Brief description of the drawings]

FIG. 1 is a schematic view of a light exposure device for modified illumination (oblique incidence illumination).

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

FIG. 3 is a plan view of an aperture provided with two linear through holes.

4 is a graph showing light intensity in a direction perpendicular to the pattern shown in FIG. 2 on the projection plane when the stop shown in FIG. 3 is used, and FIG. 4 (a) is a graph showing light intensity when there is no defocus; (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 a defocus. 1.5
It is a graph which shows the light intensity in case of μm.

5A and 5B are graphs showing light intensity in a direction perpendicular to the pattern of FIG. 2 on a projection surface when a conventional round hole stop is used, and FIG. 5A shows light intensity without defocus. (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 a graph showing the light intensity. Gap
It is a graph which shows the light intensity in the case of 1.5 micrometers.

FIG. 6 is a plan view of an aperture provided with one linear through hole.

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

FIG. 8 is a plan view of an aperture 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 shown in FIG. 7 on the projection plane when the stop shown in FIG. 8 is used, and FIG. 9A shows the light intensity distribution in the case of a focal position. (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 a graph. Defocus
It is a graph which shows the light intensity distribution in the case of 0.6 micrometer,
(E) is a graph showing a light intensity distribution when the focus shift is 0.8 μm, and (f) is a graph showing a light intensity distribution when the focus shift is 1.0 μm.

10A and 10B are graphs showing a three-dimensional light intensity distribution according to the pattern of FIG. 7 on a projection plane when a conventional round hole stop is used, and FIG. (B) is a graph showing a light intensity distribution in the case of a defocus of 0.2 μm, and (c) is a defocus of 0.4 μm.
7D is a graph showing a light intensity distribution in the case of m, (d) is a graph showing a light intensity distribution in the case of a defocus of 0.6 μm, and (e) is a graph showing a light intensity distribution in the case of a 0.8 μm defocus. (F) is a graph showing a light intensity distribution in a case where the defocus is 1.0 μm.

FIG. 11 is a plan view of a diaphragm having orthogonal linear through holes.

FIG. 12 is a partial plan view of a line and space pattern having a triangular wave shape.

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

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

FIG. 15 is a plan view of an aperture stop provided with two sets of two rectangular through holes distant from the optical axis.

16 is a graph showing a three-dimensional light intensity distribution corresponding to the pattern of FIG. 14 on the projection plane when the stop of FIG. 15 is used, and FIG. 16 (a) shows the light intensity distribution at the focus position. It is a graph, (b) is a graph which shows the light intensity distribution at the time of 0.2 micrometer of defocus, and (c) is defocus.
It is a graph which shows the light intensity distribution at the time of 0.4 micrometer.

17 is a graph showing a three-dimensional light intensity distribution according to the pattern of FIG. 14 on the projection plane when the stop of FIG. 15 is used, and FIG. 17 (a) shows the light intensity when the defocus is 0.6 μm; (B) is a graph showing a light intensity distribution when the defocus is 0.8 μm, (c) is a graph showing a light intensity distribution when the defocus is 1.0 μm, and (D) is a graph showing a light intensity distribution in the case of a defocus of 1.2 μm.

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

19 is a graph showing a three-dimensional light intensity distribution corresponding to the pattern of FIG. 14 on the projection plane when the conventional stop of FIG. 19 is used, and FIG. (B) is a graph showing a light intensity distribution when the defocus is 0.2 μm, and (c) is a graph showing a 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 plane when the conventional stop of FIG. 19 is used, and FIG. 20 (a) shows a case where the defocus is 0.6 μm; It is a graph which shows a light intensity distribution, (b) is defocus 0.8.
7 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 a 1.0 μm defocus, and (d) is a light intensity distribution in a case of a 1.2 μm defocus. FIG.

FIG. 21 is a plan view of an aperture provided with two sets of one block through hole away from the optical axis.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Light source 2 ... Aperture 3 ... Condenser lens 4 ... Deformation illumination system 4 5 ... Photomask (reticle) 5 6 ... Projection lens 6 7 ... Resist film (projection surface) φ ... Incident angle 11 ... Light-shielding 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 Shield Stripe 32 ... Triangular wave transparent hole stripe 33 ... Line & space pattern 34, 45 ... Aperture 35, 36 ... Block transparent hole 38 ... Triangular wave stripe pattern in DRAM 51 ... Fly-eye lens 52 ... Liquid crystal plate

Continuation of front page (56) References JP-A-4-225358 (JP, A) JP-A-5-55110 (JP, A) JP-A-5-217839 (JP, A) JP-A-5-326365 (JP) , A) (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/027 G03F 7/20 521

Claims (10)

(57) [Claims] 1. A method of projecting and exposing a pattern on a photomask to a resist on a substrate using a modified illumination system including a light source, an aperture, and a condenser lens, and an exposure apparatus including a photomask and a projection lens. A light exposure method, wherein when the pattern of the photomask is a line-and-space pattern, one linear light illumination parallel to the pattern is used at a position away from the optical axis of the exposure apparatus. . 2. A method of projecting and exposing a pattern on a photomask to a resist on a substrate using a modified illumination system including a light source, an aperture, and a condenser lens, and an exposure apparatus including a photomask and a projection lens. When the pattern of the photomask is a line-and-space pattern, two linear light illuminations parallel to the centrally symmetric pattern at a position away from the optical axis of the exposure apparatus are used. Exposure method. 3. The light becomes oblique incidence illumination having an angle φ with respect to an optical axis of the photomask, and 2psin φ = λ.
3. The method according to claim 1, wherein p is a set pitch of a line-and-space pattern on a projection plane, and λ is a wavelength of light. 4. A method of projecting and exposing a pattern on a photomask to a resist on a substrate using a modified illumination system including a light source, an aperture, and a condenser lens, and an exposure apparatus including a photomask and a projection lens. The pattern of the photomask has a first line and space pattern portion and a similar line and space second pattern portion.
When the pattern 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 apparatus, and a single linear light illumination parallel to the second pattern portion at a position away from the optical axis of the exposure device A light exposure method, wherein the second linear light illumination is used. 5. A method of projecting and exposing a pattern on a photomask to a resist on a substrate using a modified illumination system including a light source, an aperture, and a condenser lens, and an exposure apparatus including a photomask and a projection lens. The pattern of the photomask has a first line and space pattern portion and a similar line and space second pattern portion.
When the pattern is orthogonal to the pattern,
Two first linear light illuminations parallel to the first pattern portion, which are centrally symmetric at a position away from the optical axis of the exposure apparatus, and the second linear light illumination, which is centrally symmetric at a position away from the optical axis of the exposure apparatus;
A light exposure method, comprising using two second linear light illuminations parallel to a pattern portion. 6. The first linear light and the second linear light serve as oblique incidence illumination having an angle φ with respect to the optical axis of the photomask, where 2psin φ = λ (where p is a projection surface. Is a set pitch of the line and space pattern, and λ is the wavelength of light).
Or the method of claim 5. 7. A method of projecting and exposing a pattern on a photomask to a resist on a substrate using a modified illumination system including a light source, an aperture, and a condenser lens, and an exposure apparatus including a photomask and a projection lens. When the pattern of the photomask is a line-and-space pattern of a triangular wave 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. A light exposure method, comprising using illumination and a second block light illumination having a positional relationship perpendicular to the bottom surface of the triangular wave. 8. A method of projecting and exposing a pattern on a photomask to a resist on a substrate using a modified illumination system including a light source, an aperture, and a condenser lens, and an exposure apparatus including a photomask and a projection lens. When the pattern of the photomask is a line-and-space pattern in the form of a triangular wave having a base angle of θ, the center of the photomask is symmetrical at a position distant from the optical axis of the exposure apparatus, and the positional relationship between the triangular wave and the bottom is 2 A light exposure method, comprising using two first block light illuminations 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, an aperture, and a condenser lens. 10. The oblique incidence illumination in which the first block light has an angle φ _X with respect to an optical axis of the photomask,
2p sin φ _x = λ sin 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 Oblique incidence illumination having an angle φ _Y with respect to the optical axis of the optical axis of the first block light and the second block light have a relationship of 2 p sin φ _Y = λ cos θ, and the ratio of the illumination area of the first block light and the second block light is sin θ: 9. A method according to claim 7, wherein cos θ.