JP2003173956A - Method and device for exposure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for exposure, which enables exposure of good resolution mask patterns which are intermixture of L and S patterns, and isolated and complicated patterns, with fine line breadth (of not more than 0.15 μm, for instance), without changing mask. <P>SOLUTION: A phase shift mask having a phase value of three or more is formed with a desired pattern and a dummy pattern of periodicity which is superposed on the desired pattern. The phase shift mask is lit up utilizing lighting that has a peak in the vicinity of optical axis and lighting that has a peak outside the optical axis. The light that has passed through the phase shift mask is projected to a surface to be exposed by way of a projection optical system, whereby the desired pattern is transferred to the surface to be exposed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to exposure, and in particular, semiconductor chips such as IC and L & SI, display elements such as liquid crystal panels, detection elements such as magnetic heads, C
The present invention relates to an exposure apparatus and method used for manufacturing various devices such as an image pickup device such as a CD, a wide range pattern used in micromechanics, a device manufacturing method, and a device manufactured from the object to be processed. Here, micromechanics refers to a technology for applying a semiconductor integrated circuit manufacturing technology to the manufacture of a fine structure to create a mechanical system having advanced functions in the micron unit.

[0002]

2. Description of the Related Art A photolithography process is a process of transferring a mask pattern onto a photosensitive substance (resist) applied to a silicon wafer, a glass plate or the like (hereinafter simply referred to as "wafer") by using an exposure device. , Resist coating, exposure, development, etching, and resist removal processes. Of these, in exposure, resolution, overlay accuracy,
Three parameters of throughput are important. The resolution is the minimum size that can be accurately transferred, the overlay accuracy is the accuracy when overlaying several patterns on the wafer, and the throughput is the number of sheets processed per unit time.

When manufacturing a device using photolithography, a pattern written on a mask or a reticle (which terms are used interchangeably in this application) is projected onto a wafer by a projection optical system to form a pattern. Conventionally, a projection exposure apparatus for transfer is used. The projection optical system causes the diffracted light from the pattern to interfere and form an image on the wafer, and the normal exposure causes the 0th and ± 1st order diffracted lights (that is, three light fluxes) from the pattern to interfere with each other.

The mask pattern includes a periodic line-and-space (L & S) pattern in which lines are close to each other, a periodic contact hole pattern in which holes are close to each other, and lines or holes are isolated from each other without being close to each other. Although including a pattern, in order to transfer the pattern with high resolution, it is necessary to select the optimum exposure condition (illumination condition, exposure amount, etc.) according to the type of the pattern.

The resolution R of the projection exposure apparatus is the wavelength λ of the light source.
And the numerical aperture (NA) of the projection optical system are given by the following Rayleigh equation.

[0006]

[Equation 1]

Here, k ₁ is a constant determined by the developing process and the like, and in the case of normal exposure, k ₁ is about 0.5.
~ 0.7.

In response to the recent high integration of devices, there is an increasing demand for finer patterns to be transferred, that is, higher resolution. To obtain high resolution, the numerical aperture N
Increasing A and decreasing the wavelength λ are effective, but these improvements have reached their limits at this stage, and a pattern of 0.15 μm or less is formed on the wafer in the case of normal exposure. It is difficult. Therefore, conventionally, a phase shift mask technique has been proposed in which the ± 1st order diffracted light from the mask pattern is caused to interfere and form an image. The phase shift mask provides a 180 degree phase shift for adjacent light transmitting portions of the mask.
By inversion, the 0th order diffracted light is canceled out and the two ±
The first-order diffracted light is caused to interfere with each other to form an image. According to this technique, k ₁ in the above equation can be substantially 0.25, so that the resolution R can be improved and a pattern of 0.15 μm or less can be formed on the wafer.

[0009]

However, the conventional phase shift mask technique is effective for a simple pattern such as a periodic L & S pattern, but the exposure performance of an isolated pattern or an arbitrary complicated pattern ( That is, it was difficult to expose with good resolution, overlay accuracy and throughput. In particular, the semiconductor industry in recent years is
Since production is shifting to system chips in which a wide variety of patterns are mixed, it is necessary to mix a plurality of types of patterns in a mask.

On the other hand, published patent No. 14 of 1999
As disclosed in Japanese Patent No. 3085, it is conceivable to use double exposure (or multiple exposure) in which different types of patterns are separately exposed. However, this double exposure requires two masks, and therefore costs are low. As a result, the throughput was lowered because the two masks were exchanged and the exposure was performed twice.

Therefore, it is an exemplary embodiment of the present invention to provide an exposure method and apparatus capable of exposing a mask pattern having a fine line width (for example, 0.15 μm or less) with good resolution without changing the mask. To aim.

[0012]

In order to achieve the above object, an exposure method according to one aspect of the present invention comprises a desired pattern, a dummy pattern having a periodicity superimposed on the pattern, and three or more. A phase shift mask having a number of phase values of, and using the illumination light having an intensity peak near the optical axis on the pupil plane and the illumination light having an intensity peak off-axis on the pupil plane The desired pattern is transferred to the exposed surface by illuminating a shift mask and projecting the light passing through the phase shift mask onto the exposed surface through a projection optical system. An exposure method as another aspect of the present invention is an exposure method including a step of projecting an image of a mask pattern on a surface to be exposed, wherein the pattern image includes a predetermined pattern image and a dummy pattern image. However, the image of the predetermined pattern is located at the peak position of the intensity distribution of the pattern image, and the dummy pattern image has an intensity in which a peripheral intensity and an intermediate value between the peripheral intensity and the intensity of the peak position are alternately repeated. It is characterized by having a distribution. An exposure apparatus as another aspect of the present invention is characterized by having an exposure mode corresponding to the above-mentioned exposure method and projecting a mask pattern by a projection optical system.
Further, the above-mentioned mask itself constitutes another aspect of the present invention.

Illumination light having a peak in the vicinity of the optical axis has, for example, an effective light source shape of circular or σ (coherency) of 0.3 or less, and causes interference between 0th-order diffracted light and ± 1st-order diffracted light. The illumination light having an off-axis peak has, for example, a position of the peak of 0.6 with the radius of the pupil being 1.
The above is the interference of the two light fluxes of the 0th-order diffracted light and the + 1st-order or -1st-order diffracted light. The effective light source shape may be a ring zone or a quadrupole, and the illumination lights of the quadrupole may have the same σ (coherency). These illuminations can be achieved by a diaphragm disposed at a position conjugate with the pupil plane of the projection optical system of the illumination device and having the effective light source shape as an aperture. Such an exposure method and apparatus are (1) the number of phases of the mask pattern is three or more, the number of intensity values of the light intensity distribution formed on the plate is increased, and (2) the illumination light having a peak near the optical axis. To finely expose the mask pattern by (3) coarsely expose the mask with illumination light having a peak outside the axis, and (4) by appropriately selecting the (resist) threshold value of the exposed surface to obtain a desired pattern. It is formed on the exposed surface.

According to still another aspect of the present invention, there is provided a device manufacturing method in which the object to be processed is projected and exposed by using the above-mentioned exposure apparatus, and a predetermined process is performed on the object to be processed which has been projected and exposed. And steps. The claims of the device manufacturing method having the same operation as the above-described operation of the exposure apparatus extend to the devices themselves which are intermediate and final products. Further, such a device is, for example, L
& SI and VL & SI semiconductor chips, CCD, LC
D, a magnetic sensor, a thin film magnetic head, and the like.

A mask manufacturing method according to another aspect of the present invention is to form a desired pattern on a mask, superimpose a dummy pattern having periodicity on the pattern, and form three or more phase value numbers. The mask is manufactured as a phase shift mask. The mask manufactured by this method has the above-mentioned effects.

Further objects or other features of the present invention are as follows:
It will be apparent from the preferred embodiments described below with reference to the accompanying drawings.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An exemplary exposure apparatus of the present invention will be described below with reference to the accompanying drawings. Here, FIG.
FIG. 3 is a schematic block diagram of the exposure apparatus 1 of the present invention. Figure 1
As shown in FIG. 1, the exposure apparatus 1 includes an illumination device 100, a mask 200, a projection optical system 300, a plate 400,
It has a stage 450 and an imaging position adjusting device 500.

The exposure apparatus 1 of this embodiment is a projection exposure apparatus that exposes the circuit pattern formed on the mask 200 on the plate 400 by the step-and-scan method.
The present invention can apply a step-and-repeat method and other exposure methods. Here, in the step-and-scan method, the wafer is continuously scanned with respect to the mask to expose the mask pattern on the wafer, and after the exposure of one shot is completed, the wafer is step-moved to the exposure area of the next shot. This is a moving exposure method. The step-and-repeat method is an exposure method in which the wafer is moved stepwise for each batch exposure of a shot of the wafer to move the next shot to the exposure area.

The illuminating device 100 illuminates the mask 200 on which a circuit pattern for transfer is formed, and has a light source section 110 and an illumination optical system 120.

The light source section 110 is a laser 1 as a light source.
12 and a beam shaping system 114.

The laser 112 has an A wavelength of about 193 nm.
Light from a pulsed laser such as an rF excimer laser, a KrF excimer laser with a wavelength of about 248 nm, an F ₂ excimer laser with a wavelength of about 157 nm can be used. The type of laser is not limited to excimer lasers,
For example, a YAG laser may be used and the number of lasers is not limited. For example, 2 operating independently
If one solid-state laser is used, there is no coherence between the solid-state lasers, and speckle due to the coherence is significantly reduced. Further, in order to further reduce speckle, the optical system may be swung linearly or rotationally. Also,
The light source that can be used for the light source unit 110 is not limited to the laser 112, and one or a plurality of lamps such as a mercury lamp and a xenon lamp can also be used.

As the beam shaping system 114, for example, a beam expander having a plurality of cylindrical lenses or the like can be used, and the aspect ratio of the dimension of the cross-sectional shape of the parallel light from the laser 112 is converted to a desired value ( For example,
The beam shape is formed into a desired shape by changing the cross-sectional shape from rectangular to square. Beam shaping system 114
Form a light beam having a size and a divergence angle necessary for illuminating the optical integrator 140 described later.

Although not shown in FIG. 1, the light source unit 110 preferably uses an incoherent optical system for making a coherent laser light beam incoherent. The incoherent optical system converts an incident light flux into at least two light fluxes (for example, p-polarized light and s-polarized light) on a light splitting surface as disclosed in FIG. 1 of Japanese Patent Laid-Open No. 1935930. After branching, one light flux is given to the other light flux through the optical member by an optical path length difference equal to or longer than the coherence length of the laser light, and then re-directed to the split surface to be superposed on the other light flux and emitted. It is possible to use an optical system including at least one folding system as described above.

The illumination optical system 120 is an optical system for illuminating the mask 200, and in this embodiment, the condensing optical system 130.
, Optical integrator 140, and aperture stop 1
50 and a condenser lens 160. The illumination optical system 120 can be used for both on-axis light and off-axis light. The illumination optical system 120 of this embodiment may include a masking blade or a scan blade for changing the size of the transfer area on the plate 400. The illumination optical system 120 of this embodiment has a plurality of lenses and necessary mirrors, and constitutes an afocal system that is telecentric on the incident side and the exit side.

First, the condensing optical system 130 includes necessary bending mirrors, lenses, and the like, and efficiently introduces the light flux that has passed therethrough into the optical integrator 140. For example, in the condensing optical system 130, the exit surface of the beam shaping system 114 and the entrance surface of an optical integrator 140 configured as a fly-eye lens described below are optically the object plane and the pupil plane (or the pupil plane and the image plane). ) (The relationship may be referred to as a Fourier transform relationship in the present application), and the principal ray of the light flux passing through the condenser lens is positioned at the center and the periphery of the optical integrator 140. It is also kept parallel to the lens element 142.

The condensing optical system 130 is capable of changing the exposure amount of the illumination light to the mask 200 for each illumination, and an exposure amount adjusting section 132.
Is further included. The exposure amount adjusting unit 132 can change the beam cross-sectional shape of the incident light beam by changing each magnification of the afocal system. Alternatively, the exposure amount adjusting unit 13
Reference numeral 2 may be a zoom lens or the like, and the lens may be moved in the optical axis direction to change the angular magnification. If necessary, the exposure amount adjusting unit 132 adjusts the output of the laser 112 and / or a part of the optical system based on the detection result obtained by dividing the incident light flux by the half mirror and detecting the light amount by the sensor. You can The exposure adjustment unit 132
The light amount ratio between the central portion and the peripheral portion of the aperture stop 150, which will be described later, is adjusted by replacing the optical element (for example, a light amount adjustment (ND) filter) and / or changing the image forming magnification with a zoom lens. You can also do it. As will be described later, the exposure amount adjusting unit 132 may include the desired pattern and / or the plate 400, as described later.
The exposure amount can be adjusted on the basis of the contrast required in the above. For example, if the pattern shape is important, the ratio of the exposure amount of the illumination light having the peak on the optical axis may be relatively increased, and if the contrast is important, the illumination light having the off-axis peak may be used. The exposure dose ratio may be relatively increased.

For example, the exposure adjusting unit 132 creates illumination light whose intensity is higher in the central portion than in the peripheral portion as shown in FIG.
It makes it possible to use a circular aperture stop 150F as shown in (F). Here, FIG. 2 is a light intensity distribution of the illumination light in which the central portion has a higher light intensity than the peripheral portion. FIG. 3F is a schematic plan view of the circular aperture stop 150F. In the present application, “illumination light obtained by combining illumination light having a peak near the optical axis and illumination light having an off-axis peak” includes the illumination light as shown in FIG. The aperture stop 150F is
It is composed of a circular light transmitting portion 155 having a transmittance of 1 and an annular light shielding portion 152F having a transmittance of 0.

The optical integrator 140 uniformizes the illumination light with which the mask 10 is illuminated. A secondary light source is formed on the light emitting surface of the optical integrator 140 or on the outside thereof. As will be described later, the optical integrator 140 that can be used in the present invention is not limited to the fly-eye lens.

The fly's-eye lens is formed by arranging a plurality of lenses (lens elements) on the other surface whose focal positions are different from each other, or the focal position of the surface on the light source side is outside the surface on the reticle side. It is an array of lenses.

In the present embodiment, the fly-eye lens is constructed by combining a large number of lens elements each having a square cross section according to the shape of the mask 200.
It does not exclude lens elements having a rectangular, hexagonal or other cross-sectional shape. Exit face 140 of fly-eye lens
b or multiple point light sources (effective light sources) formed in the vicinity thereof
The respective luminous fluxes from the above are superposed on the mask 200 by the condenser lens 160. As a result, the entire mask 200 is uniformly illuminated by a large number of point light sources (effective light sources).

The optical integrator 140 applicable in the present invention is not limited to a fly-eye lens, and for example,
It may be replaced with the optical integrator 140A shown in FIG. Here, FIG. 27 is an enlarged perspective view of the optical integrator 140A. The optical integrator 140A includes two sets of cylindrical lens array (or lenticular lens) plates 144 and 14.
It is constructed by stacking six. The first and fourth sets of cylindrical lens array plates 144a and 144
b has a focal length f1 respectively, and the second and third sets of cylindrical lens array plates 146a and 146b
Has a focal length f2 different from f1. The same set of cylindrical lens array plates is arranged at the focal position of the other party. Two sets of cylindrical lens array plates 144 and 1
46 are arranged at right angles, and F-numbers (that is,
Create light fluxes with different lens focal lengths / effective apertures. Needless to say, the number of sets of the optical integrator 140A is not limited to two.

The fly-eye lens 140 may be replaced with an optical rod. The optical rod has a rectangular cross section in which the illuminance distribution that was non-uniform on the entrance surface is made uniform on the exit surface, and the cross-sectional shape perpendicular to the rod axis has an aspect ratio substantially the same as that of the illumination region. If the optical rod has a power in a sectional shape perpendicular to the rod axis, the illuminance on the emission surface is not uniform, and therefore the sectional shape perpendicular to the rod axis is a polygon formed by only straight lines. In addition, the fly-eye lens 130
It may be replaced with a diffractive element having a diffusing action.

Immediately after the emission surface 140b of the optical integrator 140, an aperture stop 150 having a fixed shape and diameter is provided. Aperture stop 15 of this embodiment
0 is the mask 20 using illumination light having a peak near the optical axis and illumination light having an off-axis peak (that is, by projecting these sequentially or in a combined state).
It has an opening shape for illuminating 0. As described above, according to the present invention, an aperture stop that provides illumination light having a peak near the optical axis and an aperture stop that provides illumination light having an off-axis peak are prepared, and one of them is projected onto the mask 200 first. Then, thereafter, the case of projecting the other on the mask 200 is also included. One of the features of the present invention is to solve the problems associated with the replacement of the mask 200, since the replacement of the aperture stop 150 is not a problem unless the mask 200 is replaced. The aperture stop 150 is the pupil plane 32 of the projection optical system 300.
The aperture shape of the aperture stop 150, which is provided at a position conjugate with 0, corresponds to the effective light source shape of the pupil plane 320 of the projection optical system 300.

The illumination light having a peak in the vicinity of the optical axis has a coherency σ of 0.3 or less, which causes interference between the 0th-order diffracted light and the ± 1st-order diffracted light. The peak position of the illumination light having an off-axis peak is 0.6 or more when the radius of the pupil is 1, and causes the interference of two light fluxes of the 0th-order diffracted light and the + 1st-order or -1st-order diffracted light. Where coherency σ
Is the numerical aperture (NA) of the projection optical system 300 on the mask 200 side.
Is the NA of the illumination optical system 120 on the mask 200 side. Illumination having a peak in the vicinity of the optical axis may be referred to as low-coherency σ illumination, normal illumination, or the like. Illumination having a peak off-axis may be called illumination with large coherency σ, oblique incidence illumination, modified illumination, or the like.

Referring to FIGS. 3 to 6, the aperture stop 150.
A description will be given of an exemplary shape applicable to. 3 to 6 are schematic plan views of exemplary shapes of the aperture stop 150. FIG. 3A shows a circular opening 151 having a relatively small radius for providing illumination light having a peak near the optical axis.
It is a schematic plan view of an aperture stop 150A having a. The aperture stop 150A has a light transmitting portion having a transmittance of 1 and formed of a circle 151, and a light shielding portion 152A.

FIG. 3B shows an aperture stop 15 having a light transmitting portion having a transmittance of 1 formed of a quadrupole circle 153 and a light shielding portion 152B for providing illumination light having a peak off-axis.
It is a schematic plan view of OB. The circular aperture 153 provides illumination light with coherency σ = 1 or less, and ± 4 for each.
It is arranged at 5 degrees and ± 135 degrees. Preferably, the coherencies σ of the illumination lights provided by the circles 153 are equal to each other.

FIG. 3C shows a transmittance of 1 consisting of an annular aperture 154 for providing illumination light having an off-axis peak.
Aperture stop 150 having a light transmitting portion and a light shielding portion 152C
It is a schematic plan view of C.

FIG. 3D has a circular opening 151 shown in FIG. 3A and a circular opening 153 shown in FIG. 3B.
It is a schematic plan view of an aperture stop 150D configured as a stop for dipole illumination. Therefore, the aperture stop 150D provides illumination light in which illumination light having a peak near the optical axis and illumination light having an off-axis peak are combined. Aperture stop 150D
The circles 151 and 153 have the same size. The aperture stop 150D includes a light transmitting portion having a transmittance of 1 and formed of circles 151 and 153, and a light shielding portion 152D having a transmittance of 0.

FIG. 3E is a schematic plan view of an aperture stop 150E having a circular aperture 151 shown in FIG. 3A and an annular aperture 153 shown in FIG. 3C. Therefore, the aperture stop 150E also provides illumination light in which illumination light having a peak near the optical axis and illumination light having an off-axis peak are combined. The aperture stop 150E has a light transmitting portion having a transmittance of 1 and formed of circles 151 and 154, and a light shielding portion 152D having a transmittance of 0.

Further, the shapes of the openings 151 and 153 can be variously changed, such as a quadrangle or other polygon, or a part of a fan shape. Further, the coherency σ may exceed 1.
Such a modified example will be described with reference to FIGS. 4 and 5. Here, FIGS. 4A and 4B are aperture stops 150G and 150H which are modified examples of the aperture stop 150D shown in FIG. 3D.
2 is a schematic plan view of FIG. FIG. 4C is a schematic plan view of an aperture stop 150I which is a modification of the aperture stop 150E shown in FIG.

The aperture stop 150G has a coherency σ of 1 with a circular aperture 151A somewhat larger than the circular aperture 151.
And a light-shielding portion 152G having a transmittance of 0 and having a rectangular opening 153A partially exceeding the light transmittance. The present inventor has found that the pattern image formed on the plate 400 becomes clear when the illumination light whose coherency σ partially exceeds 1 is used. The aperture stop 150H has a light-transmitting portion having a transmittance of 1 and a light-shielding portion 152H having a transmittance of 0, which includes a circular opening 151 having a coherency σ of 1 or less and a fan-shaped opening 153B. Fan-shaped opening 1
The size of 53B can be adjusted arbitrarily. The aperture stop 150I has a circular aperture 151 and a light-transmitting portion having a transmittance of 1 formed of an annular zone (or a rectangular zone) 154A partially exceeding the coherency σ = 1, and a light-shielding portion 152I having a transmittance of 0. The functions of the aperture diaphragms 150G to I are the same as those of the above-mentioned aperture diaphragm 150D and the like, and therefore detailed description thereof is omitted here.

FIG. 5 shows a schematic plan view of an aperture stop 150J configured as a nine-pole illumination stop as another modification applicable to the aperture stop 150. Aperture stop 150J
Is a circular opening 151B that is slightly larger than the circular opening 151.
And a circular opening 153C having a coherency σ of 1 or less,
Circular aperture 151 with coherency σ partially exceeding 1
It has a light-transmitting portion having a transmittance of 1 and a light-shielding portion 152J having a transmittance of 0, which includes a circular opening 153D having the same size as B. The circular openings 153C are provided at positions of 0 degrees, 90 degrees, 180 degrees and 270 degrees, and the circular openings 153D are provided at positions of ± 45 degrees and ± 135 degrees. Aperture stop 150
Since the function of J is also the same as that of the aperture stop 150D and the like described above, detailed description thereof will be omitted here.

To select a desired aperture stop 150 from a plurality of types of aperture stops 150, the aperture stop 150A is used.
To 150J may be arranged in, for example, a disc-shaped turret (not shown) and the turret may be rotated when switching. Accordingly, the illumination device 120 can first illuminate the mask 200 with one of the illumination light having a peak on the optical axis and the illumination light having an off-axis peak, and then can illuminate the mask 200 with the other. . Further, in the illumination light in which the illumination light having the peak on the optical axis and the illumination light having the peak on the off-axis are combined, the above-mentioned exposure amount adjusting unit 1
32 can change the respective exposure dose ratios.

The condenser lens 160 collects as much light as possible from the fly-eye lens 140 as much as possible so that the principal rays are parallel, that is, telecentric.
0 is Koehler illumination. The mask 200 and the exit surface 140b of the fly-eye lens 140 are arranged in a Fourier transform relationship.

If necessary, the exposure apparatus 1 has a variable width slit for controlling illuminance unevenness, a masking blade (aperture or slit) for limiting an exposure area during scanning, and the like. When the masking blade is provided, the masking blade and the exit surface 140b of the fly-eye lens 140 are arranged in a Fourier transform relationship, and are provided at a position that is technically substantially conjugate with the mask 200 surface. The light flux transmitted through the opening of the masking blade is used as the illumination light of the mask 200. The masking blade is a diaphragm that can automatically change the opening width, and is used for the plate 400 (of the opening slit) described later.
The transfer area can be changed vertically. Further, the exposure apparatus may further include a scan blade having a structure similar to the above-mentioned masking blade, which makes it possible to change the lateral direction of the transfer area (as a one-shot scan exposure area) of the plate 400. The scan blade is also a diaphragm whose opening width can be automatically changed, and is provided at a position which is substantially conjugate with the surface of the mask 200. Thus, the exposure apparatus 1 can set the size of the transfer area according to the size of the shot to be exposed by using these two variable blades.

The mask 200 is made of, for example, quartz, on which a circuit pattern to be transferred is formed, and is supported and driven by a mask stage (not shown). Mask 20
The diffracted light emitted from 0 passes through the projection optical system 300 and is projected onto the plate 400. The plate 400 is an object to be processed and is coated with a resist. The mask 200 and the plate 400 are arranged in an optically conjugate relationship. Since the exposure apparatus 1 of this embodiment is a step-and-scan type exposure apparatus (that is, a scanner), the mask 20
0 and plate 400 to scan mask 200
Pattern is transferred onto the plate 400. In the case of a step-and-repeat type exposure apparatus (that is, a “stepper”), the exposure is performed with the mask 200 and the plate 400 kept stationary.

The mask stage supports the mask 200 and is connected to a moving mechanism (not shown). The mask stage and the projection optical system 300 are provided on, for example, a stage barrel surface plate supported by a base frame placed on a floor or the like via a damper or the like. The mask stage may have any configuration known in the art. The moving mechanism (not shown) is composed of a linear motor or the like, and the mask 200 can be moved by driving the mask stage in the XY directions. The exposure apparatus 1 scans the mask 200 and the plate 400 in a synchronized state by a control mechanism (not shown).

The mask 200 according to one aspect of the present invention is
A desired pattern and a dummy pattern with periodicity superimposed on the pattern are formed to form a phase shift mask having a phase value number of 3 or more. The mask is manufactured, for example, as a phase shift mask by forming a desired pattern, superimposing a dummy pattern having periodicity on the pattern, and setting the number of phase values to 3 or more. As will be described later, the reason why the number of phase values is three or more is to provide a difference in the exposure amount between the desired pattern and the dummy pattern.

In order to describe the pattern structure of the mask 200 of the present invention, first, an example of a desired pattern will be described. Here, the desired pattern is, for example, a gate pattern 20 as shown in FIG. Here, FIG. 6 is a schematic plan view of the gate pattern 20. As will be described later with reference to FIGS. 16 and 20, the desired pattern to which the present invention is applicable is not limited to the gate pattern 20.

The gate pattern 20 has a pair of pattern portions 21a and 21b which are aligned in parallel through the groove 26.
(Unless otherwise specified, the reference numeral 21 collectively refers to both.), And each pattern portion 21 is composed of a fine gate portion 22 passing through the B cross section and two contact portions 24 passing through the A cross section. It The gate pattern 20 is made of, for example, chrome. The contact portion is a portion in which upper and lower layers can be electrically joined to each other by forming a contact hole.

As shown in FIG. 6, both gate portions 22 are rectangles each having a fine line width L, and are aligned in parallel at a fine interval L. In other words, the gate portion 22 partially constitutes the L & S pattern. In the present embodiment, L is 0.12 μm in terms of the wafer side. The contact portions 24 are, for example, rectangles each having a line width of 3 L, and the two pairs of contact portions 24 are aligned in parallel with each other with a fine interval L. is doing. Further, in each pattern portion 21, two contact portions 24 are provided at both ends of the gate portion 22. According to the present invention, the gate portion 22 having such a fine line width and the same spacing as L and the fine spacing L (gate portion 22) are provided.
The objective is to simultaneously resolve the contact portions 24 in which a line width (that is, 3L) larger than the minimum line width L is arranged.

First, in order to resolve the two gate portions 22, a fine dummy line having the same pitch 2L as the gate portion 22 and a periodic dummy pattern with a fine interval are formed between the two gate portions 2.
A plurality of patterns are formed on both sides of 2 to form a pattern having a periodic structure. By adding a dummy pattern to form a periodic structure, the resolution performance can be improved and the line width can be controlled accurately. This periodic pattern obtains the ultimate resolution by the phase shift mask. in this case,
If the illumination light having a peak near the optical axis is used as the illumination light (such as the illumination light provided by the aperture stop 150A shown in FIG. 3A) and the transmittance of the dummy pattern is changed, the gate portion 22 It is possible to choose the threshold of the resist so as to distinguish from the dummy pattern.

Such an exposure method requires a dummy pattern to partially overlap the contact portion 24, and a fine pattern having a line width L is transferred to the plate 400. Therefore, although such an exposure method can resolve the gate portion 22, the dummy pattern superimposed on the contact portion 24 remains at the time of transfer. As a result, the contact portion 24 has a line width of 3L.
Pattern is not transferred to the plate 400 and the line width L
Will be transferred to the plate 400 as a periodic pattern. In other words, such an exposure method has a line width of 2
It is not possible to maintain the shape of a pattern thicker than twice during transfer.

Therefore, in the present embodiment, the exposure amount of the desired pattern 20 and the dummy pattern is made different by setting the number of phase values of the phase shift mask to three or more, and the desired pattern 20 is resolved on the plate 400. I was made to be imaged. The phase shift mask at this time is the mask 200 according to one aspect of the present invention. Hereinafter, the phase shift mask 200 of the present invention will be described with reference to FIG. 7. Here, FIG.
(A) is a schematic plan view showing a transmittance distribution of the phase shift mask 200A. FIG. 7B shows the phase shift mask 2
It is a schematic plan view showing the phase distribution of 00A. Characteristically,
As shown in FIG. 7B, the phase shift mask 200 of the present invention has three or more phase value numbers. As shown in FIG. 7, the phase shift mask 200 has a desired pattern 210.
And a mask pattern 260 including a dummy pattern 240.

The desired pattern 210 is the gate pattern 2
Although it corresponds to 0, the transmittance of the light transmitting portion 234 of the contact portion 210 is between 0% and 50% (25% in this embodiment).
Is set to. However, in this embodiment, the plate 400
The purpose is to transfer the gate pattern 20 onto the top. The desired pattern 210 is a groove (light transmitting portion) 21.
A pair of pattern portions 212a aligned in parallel with each other
And 212b (unless otherwise specified, the reference numeral 212 collectively refers to both), and each pattern portion 212
Is composed of a fine gate portion 220 passing through the B section and two contact portions 230 passing through the A section. The light transmitting portion 214 is set to have a phase of 0 degree and the transmittance is set to 100%. Both gate portions 220 are rectangles having a fine line width L, and are aligned in parallel at a fine interval L. In this embodiment, L is 0.12 μm. The gate portion 220 has a light transmittance of 0 and is formed of, for example, chrome.

On the other hand, each of the contact portions 230 is, for example, a rectangle having a line width of 3 L, and two pairs of contact portions are aligned in parallel with each other with a fine interval L. In each pattern portion 212, two contact portions 230 are provided at both ends of the gate portion 220. The present invention provides a contact in which a gate portion 220 having a fine line width and a spacing equal to L and a line width (that is, 3L) larger than the minimum line width L (of the gate portion 220) are arranged at a fine spacing L. The purpose is to simultaneously resolve the unit 230.

In order to resolve the two gate portions 220, a plurality of dummy patterns 240 are formed on both sides of the two gate portions 220 and have a periodic structure having a fine line width L and a fine interval L having the same pitch 2L. Have. Dummy pattern 2
By adding 40 to the desired pattern 210 to form a periodic structure, it is possible to improve the resolution performance and control the line width with high accuracy. This periodic pattern obtains the ultimate resolution by the phase shift mask.

The dummy pattern 240 has an edge (light transmitting portion).
241 and light transmission parts 242 and 244 which are parallel to each other. The light transmission part 241 is set to have a phase of 0 and a transmittance of 50%. In addition, as shown in FIG.
1 may be set to phase 0 and transmittance 100%. The light transmission part 241 having a transmittance of 50% is made of, for example, a MoSi-based semitransparent thin film. Here, FIG. 8 is a schematic plan view showing the transmittance distribution of a mask 200A as a modified example of the mask 200. The mask 200A has a mask pattern 260A composed of a desired pattern 210 and a dummy pattern 240A. The mask 200A has the same configuration and phase distribution as the mask 200 of FIG. 7 except for the transmittance of the light transmitting portion 241A, and thus detailed description thereof will be omitted.

Each Y of the light transmitting portions 242 and 244
The width in the direction is equal to L (0.12 μm in this embodiment). The light transmitting portions 242 and 244 are alternately arranged in the Y direction,
It has a transmittance of 100% and 50%, respectively. Transmittance 5
The 0% light transmitting portion 244 is composed of, for example, a MoSi-based semitransparent thin film.

The light transmission parts 242 and 244 are set to the phase shown in FIG. 7 (B). The phase of the light transmission part 242 becomes 0, 180, 0, 90, 0, 90 degrees from the side of the gate part 220 on the right side to 242d, c, b, a toward the right. The light transmitting portion 244 includes the phase boundary, and is located to the right of the gate portion 220 on the right side, and 244L is 180 degrees and 90 degrees.
It consists of both degrees and their boundaries. To the right of it, 244b
Is a boundary between 90 degrees and 0 degrees, and the right adjacent 244a is a boundary between 0 degrees and 90 degrees.

More specifically, the light transmitting portions 242 (ie, 242a) at both ends of FIG. 7 (A) and the light transmitting portions 244 (ie, 244a) adjacent to the light transmitting portions 242 (ie, 244a) have a phase of 90 degrees (π /
2), which is in contact with the inner side 242b of the light transmitting portion 244a, the light transmitting portion 242b, and 2 which are in contact with the 242b.
The phase of 44b is set to 0 degree. Light transmission part 244
The phase of the portion in contact with the light transmitting portion 242c on the inside of b and 242c is set to 90 degrees (or π / 2). Regarding the phase of the light transmitting portion 244c inside the light transmitting portion 242c, the outer half is set to 90 degrees (π / 2) and the inner half is set to 180 degrees (π). Innermost pair of light transmitting parts 2
The phase of 42d is set to 180 degrees (π).

The phase is set by, for example, setting the thickness and concentration of the MoSi-based semi-permeable film or changing the thickness of the substrate that constitutes the mask such as glass.
Since the phase difference is the same even if it changes by one cycle, the phase of this embodiment may be the one with the integer n × 360 degrees added.

Each contact portion 230 has light-shielding portions 232 and 236 and a light-transmitting portion 234 on which the light-transmitting portion 242 (242d) is superposed. Shading portions 232 and 236
Are formed of, for example, chrome. Area 23
Reference numeral 4 changes from the light-shielding portion to the light-transmitting portion due to the overlapping of the dummy patterns 240.

The number of dummy patterns is not particularly limited, but it is preferable that the number of cycles is long, but one cycle or more is sufficient. However, in a pattern having a symmetrical shape, the number of cycles of the periodic patterns arranged on the left and right of the pattern is the same in order to maintain the symmetry. The number of cycles of the dummy pattern may be any number that can be arranged between the desired pattern that is not the dummy pattern and the pattern arranged next to it. Between the gate pattern of the embodiment shown in FIG. 18 and the double-line L & S pattern, for example, as shown in FIG.
The dummy patterns having the maximum number of cycles that can be arranged are arranged as shown in FIG. In this case, since the patterns are not symmetrical, the numbers of periods of the dummy patterns on the left and right of the gate pattern are not particularly the same (they may be the same).

Next, illumination using illumination light having a peak near the optical axis (such as the illumination light provided by the aperture stop 150A shown in FIG. 3A) (for example, FIG. 3).
Multiple illumination light generated as a sum of illumination light having an off-axis peak (such as the illumination light provided by the aperture stop 150B shown in (B)) (for example, the aperture stop 150D shown in FIG. 3D).
The phase shift mask 200 was exposed using the illumination light. FIG. 9 shows the result of the light intensity distribution generated on the plate 400, which will be described later. The intensity distribution on the plate 400 can be interpreted as the exposure amount distribution of the resist on the plate 400.

The upper diagram of FIG. 9A shows the plate 4 when the mask 200 is illuminated with illumination light having a peak near the optical axis.
00 is a light intensity distribution on a cross section A formed on the surface A00. In the A cross section, a pair of contact portions 230 having a line width 3L larger than the minimum line width L of the gate portion 220 are arranged in the Y direction with a minute gap L therebetween. Also, a dummy pattern having an interval and a line width of L is formed.

The contact portion 230 includes portions P _{5 to} P ₇
However, since the light transmittances 232 and 236 have a transmittance of 0 and the light transmittance 234 has a transmittance of 25%, the pitch 2
It has a periodic pattern of L. The portion _{P 5} to _{P 7,} the intensity peak value (intensity I1) and intermediate strength (intensity I2)
Is formed. The light transmitting portion 214 corresponding to the portion P ₃ has the transmittance of 100% and the phase of 0 degree, and thus has the light intensity I3 in the portion P ₃ . Since the phases of the light transmitting portions 214 and 234 are inverted by 180 degrees, it is effective for enhancing the contrast.

The dummy pattern 240 has a contact portion 2
The pitch 2L has a periodic distribution having an intermediate intensity I2 and an intensity I3 close to the peripheral intensity on both sides of 30. That is, part P
_The light transmitting portion 232 corresponding to the portion P ₂ starting from the side next to ₇ toward the outside has the transmittance of 100%, and thus has the light intensity I3 similarly to the light transmitting portion 214. The phase difference between the adjacent light transmitting portion 244 corresponding to the next portion _{P 4} parts _{P 2} is 90 ° (π / 2) Since the light intensity in a portion _{P 4} I2
Have.

The middle diagram of FIG. 9A shows the plate 40 when the mask 200 is illuminated with illumination light having an off-axis peak.
It is the light intensity distribution of the A cross section formed on 0. When the mask 200 is illuminated with illumination light having an off-axis peak, a fine pattern is not resolved (that is, the pattern 24 shown in FIG.
4 is not resolved), the portions P ₂ and P ₄ corresponding to the dummy pattern 240 are imaged as the intensity I2 ′, and the two contact portions 230 are 3 L in length and are separated from each other by the distance L. The pitch is 4L, and the contrast is low, but the intensity peak value (intensity I1 ') and the intermediate intensity (intensity I2')
And resolve.

The lower part of FIG. 9 (A) is formed on the plate 400 when the mask 200 is illuminated by illumination light obtained by adding illumination light having a peak near the optical axis and illumination light having an off-axis peak. It is a light intensity distribution. That is, the lower diagram of FIG. 9A is the addition of the upper diagram and the middle diagram of FIG. In this way, the mask 20 is illuminated by two types of illumination light.
When 0 is illuminated, a five-valued light intensity distribution is formed on the plate 400. In order to resolve the contact portion 230, the intensity T1 = I2 + I1 ′ to the intensity T2 = I2 + I
It will be appreciated that intensity values between 2'may be set to the resist threshold.

On the other hand, the upper part of FIG. 9B shows the light intensity distribution on the B section, which is formed on the plate 400 when the mask 200 is illuminated with illumination light having a peak near the optical axis. In the B cross section, a pair of gate portions 220 are arranged in the Y direction with a minute gap L therebetween. Light transmission part 21
Since 4 and 242 have 100% transmission, they have a light intensity I3 for the B section. The light transmitting portion 244 has a phase difference of 90 degrees (π / 2) with the adjacent light transmitting portion 244, and the light intensity I
Have two. As a result, the dummy pattern 240 becomes a periodic pattern in which the intermediate intensity I2 and the peripheral intensity I3 are repeated at the same pitch 2L as the gate portion 220. Further, the gate portion 22 of the pattern portion 21 has a phase difference of 180 degrees (π) from the adjacent one.
And has a light intensity I1.

The middle part of FIG. 9B shows the plate 40 when the mask 200 is illuminated with illumination light having an off-axis peak.
It is a light intensity distribution of B section formed on 0. When the mask 200 is illuminated with illumination light having an off-axis peak, the fine phase shift pattern is not resolved (that is, the pattern 244 shown in FIG. 7 is not resolved), and a portion P ₂ corresponding to the dummy pattern 240 is obtained. And P ₄ are imaged as intensity I2 ′,
Since the two gate portions 220 have a length L and are separated from each other by an interval L, the pitch is 2L. However, the two gate portions 220 act as an isolated pattern and have a low contrast but an intensity peak value (intensity I).
1 ') and an intermediate intensity (intensity I2') to resolve.

The lower part of FIG. 9 (A) is formed on the plate 400 when the mask 200 is illuminated by illumination light obtained by adding illumination light having a peak near the optical axis and illumination light having an off-axis peak. It is a light intensity distribution. That is, the lower diagram of FIG. 9B is the addition of the upper diagram and the middle diagram of FIG. In this way, the mask 20 is illuminated by two types of illumination light.
When 0 is illuminated, a five-valued light intensity distribution is formed on the plate 400. In order to resolve the contact portion 230, the intensity T1 = I2 + I1 ′ to the intensity T2 = I2 + I
It will be appreciated that intensity values between 2'may be set to the resist threshold.

As a result, in order to resolve the desired pattern 210 on the plate 400 without exchanging the mask 200, the threshold value of the resist of the plate 400 may be set between T1 and T2.

If only the illumination light having a peak in the vicinity of the optical axis is used, the dummy pattern 240 can be obtained by setting the resist threshold value between I1 and I2 from the upper diagram of FIG. 9B.
It is possible to transfer only the gate portion 220 without transferring. On the other hand, from the upper diagram of FIG. 9A, if the threshold value of the resist is set between I2 and I3, only the contact portion 230 can be transferred without transferring the dummy pattern 240, but the threshold value is I1. If set between I2, the dummy pattern remains in the region 234 of the contact part 230, and the contact part 230 is not correctly transferred to the plate 400. The present embodiment solves this problem.

Since the mask 200 has a periodic structure with a pitch of 2 L and three phases, the light intensity distribution on the plate 400 has a ternary periodic structure due to the illumination light having a peak near the optical axis. That is, the light intensity has the intensity peak value I1 at the boundary where the phase difference is π, the intermediate intensity I2 at the boundary where the phase difference is π / 2, and the periodicity of the pitch 2L having the intensity three values that becomes the intensity I3 at other boundaries. It has a wide distribution.

In order to prevent the fine portion from being resolved and not having a pseudo periodic structure, this embodiment uses the mask 2.
00 is illuminated with illumination light having an off-axis peak. The illumination light having a peak off-axis forms a flat light intensity distribution without resolving the periodic phase shift pattern with a pitch of 2 L or less, which is equal to or less than the limit resolution, but has a ternary light intensity distribution due to the transmittance distribution. It is formed on the plate 400. The transmittance distribution is pitch 2
Form a periodic distribution equal to or less than the limit resolution of L so that the periodic pattern is not resolved for illumination light having an off-axis peak, and the periodic pattern for illumination light having a peak near the optical axis. To be resolved. That is, the transmittance is 0
% Of a portion covered by the chromium film or the like P ₅ is the intensity peak value I
However, since the line width L is not resolved, it is blurred and the interval L
The line is not separated from the adjacent line and has a line width of 3L as shown in the middle diagrams of FIGS. 9A and 9B.

The portion covered with the semi-permeable membrane having the transmittance of 50% has the intermediate intensity value I2 ', but the line width L is not resolved, so that the line is blurred and is not separated from the adjacent line and is flat. Intensity distribution, and a very gentle periodic distribution. The portion 234 covered with a semi-permeable film having a transmittance of 25% is made a semi-permeable film because the periodic structure at the time of vertical illumination is interrupted when the transmittance is 0%.
In this case as well, the line width L is not resolved, so that the line is blurred and is not separated from the line next to the line having the interval L, and a flat intensity distribution close to the intensity peak value I1 ′ at the transmittance of 0% on both sides is obtained.

From the above, the addition of the ternary intensity distribution having a periodic structure and the intensity distribution resolving only a large portion is performed by the mask 200 having the transmittance distribution and the phase distribution as shown in FIGS. And 200A are realized by multiple illumination including both illumination light having a peak near the optical axis and illumination light having an off-axis peak (sequentially or simultaneously).

The projection optical system 300 transmits the diffracted light that has passed through the mask pattern 260 formed on the mask 200 to the plate 4.
00 has an aperture stop 320 for forming an image. The projection optical system 300 includes an optical system including only a plurality of lens elements, an optical system including a plurality of lens elements and at least one concave mirror (catadioptric optical system), a plurality of lens elements and at least one kinoform. An optical system having a diffractive optical element such as, an all-mirror type optical system, or the like can be used. When correction of chromatic aberration is required, a plurality of lens elements made of glass materials having different dispersion values (Abbe values) may be used, or the diffractive optical element may be configured to generate dispersion in the direction opposite to the lens element. To do. As described above, the shape of the effective light source formed on the pupil plane 320 of the projection optical system 300 is the same as the shape shown in FIGS.

The plate 400, which is a wafer in this embodiment, includes a wide range of liquid crystal substrates and other objects to be processed. Photoresist is applied to the plate 400. The photoresist coating process includes a pretreatment, an adhesion improver coating treatment, a photoresist coating treatment, and a prebake treatment. Pretreatment includes washing, drying and the like. The adhesion improver coating process is surface modification to increase the adhesion between the photoresist and the base (that is, hydrophobicity by applying a surfactant).
HMDS (Hexamethyl-dis)
coating or steaming an organic film such as ilazane). Pre-baking is a baking (baking) process, but it is softer than that after development and removes the solvent.

The plate 400 is supported by the wafer stage 450. Since the stage 450 may have any configuration known in the art, detailed description of its structure and operation will be omitted here. For example, stage 45
0 is a plate 400 in the XY directions using a linear motor.
To move. The mask 200 and the plate 400 are, for example, synchronously scanned, and the positions of a mask stage and a wafer stage 450 (not shown) are monitored by, for example, a laser interferometer, and both are driven at a constant speed ratio. The stage 450 is provided, for example, on a stage surface plate supported on a floor or the like via a damper, and the mask stage and the projection optical system 300 are, for example, a base on which the lens barrel surface plate is placed on the floor or the like. It is provided on a lens barrel surface plate (not shown) supported on the frame via a damper or the like.

The image forming position adjusting device 500 includes the stage 45.
It is connected to 0 and moves the plate 400 together with the stage 450 in the Z direction shown in FIG. 1 within the range of the depth of focus to adjust the image forming position of the plate 400. If necessary, the exposure apparatus 1 can eliminate variations in the imaging performance within the depth of focus by performing the exposure multiple times on the plates 400 arranged at different positions in the Z direction. The image-position adjusting device 500 may use any technique known in the art, such as a rack (not shown) extending in the Z direction, a pinion (not shown) connected to the stage 450 and movable on the rack, and a means for rotating the pinion. Since it can be applied, detailed description is omitted here.

In exposure, the light beam emitted from the laser 112 is incident on the illumination optical system 120 after the beam shaping system 114 shapes the beam into a desired beam shape. The condensing optical system 130 efficiently introduces the light flux that has passed through it into the optical integrator 140.
At that time, the exposure amount adjusting unit 132 adjusts the exposure amount of the illumination light. The optical integrator 140 makes the illumination light uniform, and the aperture stop 150 forms illumination light in which illumination light having a peak near the optical axis and illumination light having an off-axis peak are combined. The illumination light is condensed by the condenser lens 16
The phase shift mask 200 is illuminated through 0 through the optimal illumination condition.

A desired pattern 210 is formed on the mask 200.
And a dummy pattern 240 superimposed on the pattern 210
And a mask pattern 260 having a phase value number of 3 or more is formed. The gate part 220 is overlapped with the dummy pattern 240 to form an L & S pattern together with the dummy pattern 240, and the resolution performance is enhanced by the phase shift mask.

The light flux passing through the mask 200 is reduced and projected on the plate 400 at a predetermined magnification by the image forming action of the projection optical system 300. In the case of the step-and-scan exposure apparatus 1, the light source unit 110 and the projection optical system 300 are fixed, and the mask 200 and the plate 400 are synchronously scanned to expose the entire shot. Further, the stage 450 of the plate 400 is stepped to move to the next shot, and a large number of shots are exposed and transferred onto the plate 400. If the exposure apparatus 1 is the step-and-repeat method, the exposure is performed with the mask 200 and the plate 400 stationary.

The illumination light having a peak near the optical axis illuminates the phase shift mask 200 to form a fine periodic pattern intensity distribution on the plate 400. Illumination light having an off-axis peak illuminates the mask 200 to roughly expose it. The three or more phase values assigned to the phase shift mask are such that the illumination light having a peak near the optical axis and the illumination light having an off-axis peak form a ternary light intensity distribution on the plate 400. And their combined illumination light makes it possible to form a five-valued light intensity distribution.
As a result, the desired pattern 210 is formed on the plate 4 by appropriately selecting the resist threshold value of the plate 400.
00 can be formed. As a result, the exposure apparatus 1 transfers the pattern to the resist with high accuracy to obtain a high quality device (semiconductor element, LCD element, image pickup element (CC
D) and thin film magnetic heads).

Next, with reference to FIGS. 28 and 29, an embodiment of a device manufacturing method using the above-described exposure apparatus 1 will be described. FIG. 28 is a flow chart for explaining the manufacture of devices (semiconductor chips such as IC and L & SI, LCDs, CCDs, etc.). Here, manufacturing of a semiconductor chip will be described as an example. In step 1 (circuit design), the device circuit is designed. In step 2 (mask manufacturing), a mask having the designed circuit pattern is manufactured. In step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and a mask and a wafer are used to form an actual circuit on the wafer by the lithography technique of the present invention. Step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer prepared in Step 4, and an assembly process (dicing,
Bonding), packaging process (chip encapsulation), etc. are included. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device created in step 5 are performed. Through these steps, the semiconductor device is completed and shipped (step 7).

FIG. 29 is a detailed flowchart of the wafer process in Step 4. In step 11 (oxidation), the surface of the wafer is oxidized. Step 12 (CVD)
Then, an insulating film is formed on the surface of the wafer. Step 13
In (electrode formation), electrodes are formed on the wafer by vapor deposition or the like. In step 14 (ion implantation), ions are implanted in the wafer. In step 15 (resist processing), a photosensitive agent is applied to the wafer. In step 16 (exposure), the exposure apparatus 1 exposes the circuit pattern of the mask onto the wafer. In step 17 (development), the exposed wafer is developed. In step 18 (etching), parts other than the developed resist image are removed. Step 19
In (resist stripping), the resist that has become unnecessary after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

[0090]

EXAMPLE 1 In Example 1, the phase shift mask 200 shown in FIG. 7, a KrF excimer laser (wavelength 248 nm) as the laser 112, and a projection optical system 30 with NA of 0.60 are used.
0 and 0 were used for the exposure apparatus 1.

The exposure apparatus 1 is provided with illumination light having a peak in the vicinity of the optical axis (such as the illumination light provided by the aperture stop 150A shown in FIG. 3A) (aperture stop 1 shown in FIG. 3B).
Quadrature illumination light having an off-axis peak (such as the illumination light provided by 50B) (coherency σ ₀ at the center position of each circular aperture in FIG. 3D is 0.5, and coherency σ of the size of each side σ _{1 is set} to 0.3), and illumination light having a peak near the optical axis and illumination light having an off-axis peak are combined (illumination light provided by the aperture stop 150D shown in FIG. 3D). Each of them was exposed with a quintuple illuminating light (coherency σ of the central portion was 0.3, and others were the same as the quadrupole illuminating light). Further, the exposure amount adjusting unit 132 sets the intensity ratio of the illumination light having a peak near the optical axis of the quintuple illumination light and the illumination light having an off-axis peak to 2: 1 (illumination condition 1).

The exposure result under the illumination condition 1 is shown in FIG. Referring to FIG. 10A, when the illumination light having a peak near the optical axis is used, only the minute periodic structure is exposed. Referring to FIG. 10B, when the quadrupole illumination light is used, only the large pattern portion is exposed and the fine periodic pattern is not resolved. FIG. 10 (C)
It is understood that, when the quintuple-pole illumination light obtained by multiplexing these is used, the entire desired gate pattern 210 is resolved.

The light intensity distribution on the plate 400 is A
The cross section is shown in FIG. 11, and the B cross section is shown in FIG.
It is understood that the marginal resolution has almost the same characteristics, although it is slightly different from the light intensity distribution shown in FIG. 9 because the proximity effect is strong. As a result of the multiple illumination, as shown in FIG. 10C, the resolution of a fine pattern is very good.
Pattern was formed. The line width R in Equation 1 is (λ
When / NA), divided by to be normalized by _{k 1, k 1} = 0.29
The pattern has been resolved.

Next, the same experiment was conducted by changing the illumination conditions. Here, the phase shift mask 200 shown in FIG.
And a KrF excimer laser as the laser 112, as shown in FIG.
The aperture stop 150E shown in (E) and the projection optical system 300 having an NA of 0.60 were used in the exposure apparatus 1. The coherency σ of the illumination light having a peak near the optical axis is 0.2, the outer coherency σ ₁ of the annular illumination light is 1.0, and the inner coherency σ ₀ is 0.7. In addition, the exposure adjustment unit 1
The intensity ratio between the illumination light having a peak near the optical axis of the quintuple illumination light and the illumination light having an off-axis peak was set to 4: 1 by 32 (illumination condition 2). Even under such lighting condition 2,
Good results were obtained as shown in FIG.

Next, the same experiment was conducted by changing the mask pattern. A mask 20 shown in FIG. 15 in which an L-shaped gate pattern as shown in FIG. 14 is used as a desired pattern.
0B was used. Here, FIG. 14 is a schematic plan view of a desired pattern. FIG. 15A is a schematic plan view showing the transmittance distribution of the mask 200B. FIG. 15B is a schematic plan view showing the phase distribution of the mask 200B. The exposure result for the above illumination condition 1 is shown in FIG. 16, and the exposure result for the above illumination condition 2 is shown in FIG. As shown in FIGS. 16 and 17, it can be seen that the desired pattern is well resolved on the plate 400.

Next, an example of simultaneously exposing the gate pattern and L & S will be described. The mask 200C shown in FIG. 19 having a desired pattern that is a mixture of the gate pattern and the L & S pattern as shown in FIG. 18 was used. here,
FIG. 18 is a schematic plan view of a desired pattern. FIG. 19
(A) is a schematic plan view showing a transmittance distribution of the mask 200C. FIG. 19B is a schematic plan view showing the phase distribution of the mask 200C. The phase distribution of the mask 200C has four values of 0, π / 2, π, and 3π / 2. In the phase distribution, the phase difference at the boundary of the part to be left as a pattern is π, and the phase difference at the part not to be left as a pattern is π / 2.
However, the arrangement is such that the phase difference at the boundary with the surroundings is π / 2. That is, the L & S double line is formed at the boundary between the phase components π / 2 and 3π / 2, and the double line of the gate pattern is formed at the boundary between 0 and π. A periodic pattern having an intermediate intensity other than this was formed at the boundary between 0 and π / 2, and two main lines on both sides of the gate pattern were formed at the boundary between π and π / 2.

The exposure result in this case is shown in FIG. As shown in the figure, in the exposure result, both patterns were well resolved, the gate pattern and the L & S main line had the same line width, and the reproducibility of the line width was also good.

Thus, the two main lines of the gate pattern are 0
The phase arrangement that is formed by the boundary between
Since there is a pattern at the boundary between the part of and the surrounding phase 0,
It was possible because there were no unnecessary lines. As shown in FIG. 21, a mask 200D in which two main lines of the gate pattern are formed at the boundaries of 3π / 2 and π / 2 may be used. here,
FIG. 21A is a schematic plan view showing the transmittance distribution of the mask 200C. FIG. 21B is a schematic plan view showing the phase distribution of the mask 200C.

The L & S pattern may be a single line. In this case, the mask 200E shown in FIG. 22 in which the gate pattern and the single-line L & S pattern are desired patterns may be used. Here, FIG. 22A is a schematic plan view showing the transmittance distribution of the mask 200E. FIG. 22B is a schematic plan view showing the phase distribution of the mask 200E. One line should be formed at the boundary between the phase distributions π / 2 and 3π / 2, and 3π / 2 should be left on the left of the one line so that no boundary remains.
The phase arrangement is 0.

The L & S pattern may be a single line. In this case, the mask 200E shown in FIG. 23 in which the gate pattern and the three-line L & S pattern are desired patterns may be used. Here, FIG. 23A is a schematic plan view showing the transmittance distribution of the mask 200F. FIG. 23B is a schematic plan view showing the phase distribution of the mask 200F. The 3 lines are formed at the boundary between the phase distributions π / 2 and 3π / 2, and 3π / 2, so that no boundary remains on the left side of the 3 lines,
The phase arrangement is 0.

At this time, it should be noted that the phase difference of the boundary of the part to be left as a pattern is π and the phase difference of the part not to be left as a pattern is π / 2, but the position of the boundary with the surroundings is If the phase arrangement is such that the phase difference is π (for example, the phase distribution shown in FIG.
A phase distribution such as), the part where the phase difference at the boundary with the surroundings is π (for example, the part circled in the figure of FIG. 24).
That is, an unnecessary pattern remains.

As shown in FIG. 25, L is arranged in the order of phase arrangement.
If & S is the boundary between the phases of 0 and π,
The phase arrangement is as follows. In FIG. 25, L & S is the phase π
In order to be formed at the boundary between / 2 and 3π / 2, L
The line to the right of & S is the boundary between the phases π / 2 and π / 2, but there is no problem because it does not remain as a pattern. Here, FIG. 25A shows a mask 200 having a gate pattern and an L & S pattern of three main lines as desired patterns.
It is a schematic plan view showing the transmittance distribution of G. FIG. 25 (B)
[FIG. 7] is a schematic plan view showing a phase distribution of a mask 200G.

Therefore, if such a contradiction occurs in the phase arrangement, the pitch will be partly disturbed, but since it is a portion that does not remain as a pattern, resolution does not pose a problem. Further, if such a phase disturbance is separated from the portion desired to be left as a pattern, there is no problem in the resolution performance such as line width controllability. It is also possible to use the pitch modulation in reverse for the line width control.

The isolated line as shown in FIG. 23 may have a narrow line width. In such a case, it is effective to increase the pitch on both sides. Although FIG. 26 shows an extreme case, the pitch of the phase distribution on both sides is doubled. In such a case, it is also possible to slightly change the line width of the periodic pattern around the pattern to be subjected to the line width correction and change the pitch to perform the line width correction.

In the present embodiment, the periodic intensity distribution consisting of intensity 3-values of the minimum pitch of the pattern as shown in FIG. 9 and the intensity multi-value intensity distribution distributed with a large line width are used for phase distribution 3 to 4 values, A mask having a four-valued transmittance distribution is realized by an exposure method of multiple illumination of vertical incidence and oblique incidence.
The exposure method is not limited to this, and any exposure method may be used as long as it can superimpose the intensity distributions as shown in FIG.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to these, and various modifications and changes can be made within the scope of the spirit thereof. For example, as described above, the ratio of the exposure amount of the illumination light having a peak in the vicinity of the optical axis and the exposure amount of the illumination light having an off-axis peak in Example 1 can be changed depending on the required pattern shape and contrast. For example,
If the pattern shape is important, the ratio of the exposure amount from the oblique incident component may be relatively increased, and if the contrast is important, the ratio of the exposure amount from the vertical incident component is relatively large. do it.

[0107]

According to the mask, exposure method and apparatus of the present invention, a mask pattern having a fine line width (for example, 0.15 μm or less) and a mixture of L & S patterns, isolated patterns and complex patterns can be obtained. It is suitable for high resolution exposure without changing the mask. Further, a device manufacturing method using such an exposure method and apparatus can manufacture a high quality device.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of an exposure apparatus of the present invention.

FIG. 2 is a light intensity distribution showing an example of illumination light that can be adjusted by an exposure amount adjusting unit of the exposure apparatus shown in FIG.

FIG. 3 is a schematic plan view of an exemplary shape of an aperture stop of the exposure apparatus shown in FIG.

4 is a schematic plan view of another exemplary shape of the aperture stop shown in FIG.

5 is a schematic plan view of yet another exemplary shape of the aperture stop shown in FIG. 1. FIG.

FIG. 6 is a schematic plan view of a desired pattern.

FIG. 7 is a schematic plan view of an example of the phase shift mask of the present invention.

8 is a schematic plan view of a modified example of the phase shift mask shown in FIG.

9 is a light intensity distribution appearing on the plate of the exposure apparatus shown in FIG. 1 when the mask shown in FIG. 7 is illuminated using illumination light having a peak near the optical axis and illumination light having a peak off-axis. Is.

10 is a plan view showing a pattern transferred to a plate when the mask shown in FIG. 7 is illuminated using illumination light having a peak near the optical axis and / or illumination light having a peak off-axis. .

FIG. 11 is a light intensity distribution regarding a cross section A which appears on the plate when the mask shown in FIG. 7 is illuminated by using illumination light having a peak near the optical axis and / or illumination light having a peak off-axis. .

FIG. 12 is a light intensity distribution regarding a B cross section that appears on the plate when the mask shown in FIG. 7 is illuminated using illumination light having a peak near the optical axis and / or illumination light having a peak off-axis. .

13 is a plan view showing a pattern transferred to a plate when the phase shift mask shown in FIG. 7 is illuminated under different illumination conditions.

FIG. 14 is a schematic plan view of another desired pattern.

15 is a schematic plan view of an example of a phase shift mask formed by superimposing a dummy pattern on the desired pattern shown in FIG.

16 is a result of an exposure pattern transferred to a plate when the phase shift mask shown in FIG. 15 is illuminated.

17 is a result of an exposure pattern transferred to a plate when the phase shift mask shown in FIG. 15 is illuminated under an illumination condition different from that in FIG.

FIG. 18 is a schematic plan view of still another desired pattern.

19 is a schematic plan view of an example of a phase shift mask formed by superimposing a dummy pattern on the desired pattern shown in FIG.

20 is a result of an exposure pattern transferred to a plate when the phase shift mask shown in FIG. 15 is illuminated.

21 is a schematic plan view of a modification of the phase shift mask shown in FIG.

FIG. 22 is a schematic plan view of an example of a phase shift mask formed by superimposing a dummy pattern on another desired pattern.

FIG. 23 is a schematic plan view of an example of a phase shift mask formed by superimposing a dummy pattern on another desired pattern.

FIG. 24 is a schematic plan view for explaining a phase distribution which is not preferable to be applied to the phase shift mask having the transmittance distribution shown in FIG. 23.

FIG. 25 is a schematic plan view of a modified example of the phase shift mask shown in FIG. 23.

FIG. 26 is a schematic plan view of a modified example of the phase shift mask shown in FIG.

27 is an enlarged perspective view of a modified example of the optical integrator of the exposure apparatus shown in FIG.

FIG. 28 is a flowchart for explaining a device manufacturing method having the exposure apparatus of the present invention.

29 is a detailed flowchart of step 4 shown in FIG. 28. FIG.

[Explanation of symbols]

1 Exposure device 100 lighting device 120 Illumination optical system 132 Exposure amount adjustment unit 150 aperture stop 200 mask 210 desired pattern 240 dummy pattern 260 mask pattern 300 Projection optical system 320 pupils 400 plates

Claims (18)

[Claims] 1. A phase shift mask having a desired pattern, a dummy pattern having periodicity superimposed on the pattern, and a phase value number of 3 or more is formed, and a phase shift mask is formed near the optical axis on the pupil plane. Illuminating the phase shift mask using illumination light having a peak and illumination light having an off-axis intensity peak at the pupil plane, and passing the light passing through the phase shift mask onto a surface to be exposed through a projection optical system. The desired pattern is transferred onto the surface to be exposed by projecting the image onto the surface to be exposed. 2. The exposure method according to claim 1, wherein the illumination light having a peak near the optical axis has a circular effective light source shape. 3. The exposure method according to claim 1, wherein the illumination light having a peak near the optical axis has a σ (coherency) of 0.3 or less. 4. The illumination light having the off-axis peak has a quadrupole effective light source shape.
The exposure method described. 5. The exposure method according to claim 1, wherein the illumination light having a peak off-axis has a peak position of 0.6 or more with the radius of the pupil being 1. 6. The exposure method according to claim 4, wherein the illumination lights of the respective poles of the quadrupole have the same σ (coherency). 7. The exposure method according to claim 1, wherein the illumination light having a peak off-axis has an annular effective light source shape. 8. Any one of claims 1 to 7, 17 and 18
An exposure apparatus, which has an exposure mode corresponding to the exposure method described in the item 1, and projects a mask pattern by a projection optical system. 9. The exposure apparatus according to claim 8, wherein the illumination apparatus includes a diaphragm having a quintuple-pole aperture at a position conjugate with the pupil plane of the projection optical system. 10. The illumination light having a peak off-axis is
9. The exposure apparatus according to claim 8, wherein the peak position is larger than 1 when the radius of the pupil is 1. 11. The illumination device includes an aperture having a quadrupole aperture at a position conjugate with a pupil plane of the projection optical system, in order to form illumination light having a peak off-axis. 9. The exposure apparatus according to claim 8, wherein the illumination lights of the double poles have the same coherency. 12. The illumination device includes a diaphragm having an aperture of a ring zone at a position conjugate with a pupil plane of the projection optical system and a circular aperture provided in a central portion inside the aperture of the ring zone. 9. The exposure apparatus according to claim 8, wherein: 13. The illumination device has a device that adjusts an exposure amount and / or a positional relationship between the illumination light having a peak near the optical axis and the illumination light having a peak off the axis. The exposure apparatus according to claim 8. 14. A step of projecting and exposing an object to be processed using the exposure apparatus according to claim 8, and a step of performing a predetermined process on the object to be projected and exposed. And a device manufacturing method having. 15. A device manufactured from the object to be processed, which has been projected and exposed by using the exposure apparatus according to claim 8. 16. A phase shift mask, wherein a desired pattern and a dummy pattern having periodicity superimposed on the pattern are formed and have a phase value number of 3 or more. 17. An exposure method including a step of projecting an image of a pattern of a mask onto a surface to be exposed, wherein the pattern image has a predetermined pattern image and a dummy pattern image, and the image of the predetermined pattern is the At the peak position of the intensity distribution of the pattern image, the dummy pattern image is a peripheral intensity,
The exposure method, wherein the peripheral intensity and the intermediate value of the intensity at the peak position have an intensity distribution which is repeated alternately. 18. The exposure method according to claim 17, wherein the exposure threshold of the resist on the exposed surface is between the intensity at the peak position and the intermediate value.