JPH10135118A - Projection aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid varying the image-forming characteristics of a projection optical system, even for a long operation by controlling the relative amplitude trasmittivities of one region and other regions of a binary optics element; the zero-order light of an optical source forming an image on the one region. SOLUTION: A cycle optical source 6 emits light obliquely, illuminating a pattern 7A to form a reduced image of the pattern 7A on a wafer 11, using a projection optical system 10 having a pupil (aperture) of a radius r(mm), through which this optical source 6 provides an image on a region 4 of a binary optics element 20 having a relative amplitude transmitivity of 0.652. Hence the zero-order diffraction light 8 from an object passes through the region 4, having relative amplitude transmittivity of 0.652 of the binary optics element 20 located on the pupil plane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus, and is particularly suitable for manufacturing a highly integrated LSI or the like.

[0002]

2. Description of the Related Art Recently, a projection exposure apparatus is required to have a high resolution in order to form finer patterns when manufacturing LSIs and the like. Various methods have been proposed to achieve this, one of which is the oblique incidence illumination method. This uses an annular light source (hereafter referred to as an annular light source) or independent light sources at four corners (hereinafter called a quadrupole light source) when illuminating an object, and holds the object at an angle to the optical axis. This is a method of illuminating with a group of rays.

In the case of a circular light source including the optical axis of a commonly used illumination optical system, the 0th-order diffracted light of the object is incident near the center of the pupil of the projection optical system, and the ± 1st-order diffracted light is incident on the periphery of the pupil. However, in the case of the grazing incidence illumination method, the light source is usually located away from the optical axis of the illumination optical system, and the 0th-order diffracted light passes through the periphery of the pupil. Either of the ± 1st-order diffracted lights enters the pupil and reaches the image plane even for a thin (high spatial frequency) line width. As a result, the resolving power of the oblique incidence illumination method is improved as compared with the ordinary illumination method.

[0004] However, the above oblique incidence illumination method has a problem. That is, at a line width close to the resolution limit, only one of the ± 1st-order diffracted lights (hereinafter, referred to as “1st-order diffracted light”) is incident.
Are smaller than one. For example, when the light transmitting part and the shielding part are objects having a one-to-one periodic pattern, the amplitude of the 0th-order diffracted light: the amplitude of the first-order diffracted light = 1: 2 / π = 1: 0.636. For this reason, the problem that the contrast of an image is reduced occurs. The technology to avoid this is disclosed in
-41345. FIG. 13 is a schematic diagram of an optical system of the projection exposure apparatus described in this publication. In the figure, 121 is a mask, 124 is a first lens system, 125 is a second lens system, 126
Is an aperture stop, 127 is a wafer, and 128 is an entrance pupil. First
Lens system 124, aperture stop 126, second lens system 125
Constitute an element of the projection lens (projection optical system). FIG. 14A is a diagram of the light source 111 for illuminating the mask 121 of the optical system. Since the light source forms an image on the aperture stop 126, the light source is represented by pupil coordinates. In this case, an annular portion of R = 0.8 to 1.0 expressed in pupil coordinates is a light source, and is located away from the optical axis of the projection optical system and thus the illumination optical system. FIG. 14B is a diagram of the annular filter 113 installed in the aperture stop 126, which is also represented by pupil coordinates. The amplitude transmittance of the annular filter 113 is set such that the amplitude transmittance of the central portion 114 of the opening 114 is 1, the amplitude transmittance of the opening 115 of R = 0.8 to 1.0 is 0.2 to 0.6, and the amplitude transmittance of the outer peripheral portion 116 is 0. doing.

The operation of the conventional example will be described. The light source 111 illuminates the circuit pattern on the mask 121 by oblique incidence illumination via an illumination optical system (not shown), and the projection lens forms an image of the circuit pattern on the wafer 127 and exposes it. At this time, the light source 111 forms an image at the position of the aperture stop 126. Light source
The image due to the zero-order light is an annular image shown in FIG. 14 (A) .Since the annular filter 113 is installed at the position of the aperture stop 126, the zero-order light passes through the aperture 115 and the amplitude The transmittance is 0.
It falls from 2 to 0.6. On the other hand, high-order diffracted light passing through the central portion 114 of the opening is transmitted as it is.

[0006] By the above action, the ratio of the amplitude of the 0th-order diffracted light to the amplitude of the 1st-order diffracted light becomes close to 1, and the problem of the oblique incidence illumination method is solved to achieve a high-resolution and high-contrast projection exposure apparatus. .

As another method for giving a high resolution to a projection exposure apparatus, there is a method of shortening the wavelength of exposure light. The mainstream of the 64MDRAM generation is the i-line of mercury lamp (wavelength λ = 365nm),
The DRAM generation has begun to use a KrF excimer laser (λ = 248 nm), and the 1GDRAM generation is considering the use of an ArF excimer laser (λ = 193 nm).

However, in these lasers, it is difficult to narrow the wavelength band, so that good achromatization of the lens is required. However, glass materials that transmit light in the ultraviolet region are limited, and concave and convex lenses are used. It is difficult to achromatize a lens using.

At the same time, since the transmittance is low in this wavelength range, it is necessary to keep the total glass material thickness of the lens small, which is also a hindrance to lens design.

A technique for solving the above two problems by using a diffractive optical element is disclosed in Japanese Patent Application Laid-Open No. 6-324262. In this publication, it is noted that a diffractive optical element has a wavelength dispersion opposite to that of a refractive optical element (ordinary lens), effectively acts on the achromatism of the lens, and can reduce the thickness thereof. It addresses the challenges of both achromatizing projection lenses and reducing total glass thickness.

As a diffractive optical element used for such a purpose, there is a binary optics element in which a phase distribution function is approximated stepwise.

[0012]

When the image contrast is improved by using an annular filter for adjusting the amplitude transmittance disclosed in JP-A-5-41345, a light absorption type filter is used as the annular filter. If used, the disadvantage of the oblique incidence illumination method is improved, but the absorption of light causes thermal expansion of the filter itself, and the amplitude transmittance of the 0th-order diffracted light changes, making it difficult to adjust the amplitude. The wavefront aberration increases due to the deformation of the filter and the change in the refractive index, causing a problem that the imaging characteristics themselves deteriorate.

According to the present invention, when solving the problem of the oblique incidence illumination method, the amplitude transmittances of the zero-order light and the high-order diffracted light from the object are adjusted independently of the light absorption, and the operation is performed for a long time. It is another object of the present invention to provide a projection exposure apparatus which does not change the imaging characteristics of a projection optical system, and which is stable, has high resolution and high contrast, and particularly exhibits high performance when an excimer laser is used as a light source.

[0014]

According to the present invention, there is provided a projection exposure apparatus comprising: (1-1) converting a light from a light source into a predetermined illumination light beam through an illumination optical system to illuminate a first object; (1) In a projection exposure apparatus that projects and exposes an object onto a second object by a projection optical system, a predetermined phase distribution function is approximated to the position of an aperture stop of the projection optical system by an N-stage (N ≧ 2) step structure. A binary optics element, the light source is imaged on the binary optics element, and the amplitude transmittance of the image area of the light source on the binary optics element by the zero-order light and the amplitude transmittance of other areas Is controlled by changing the number of steps of the step in the region, or by shifting the shape of the step from the predetermined phase distribution function.

In particular, (1-1-1) an image area of the binary optics element due to the zero-order light of the light source is located away from the optical axis of the projection optical system. (1-1-2) The amplitude transmittance of the image region of the light source on the binary optics element due to the zero-order light is lower than the amplitude transmittance of the other regions. (1-1-3) The light source is located apart from the optical axis of the illumination optical system. It is characterized by

Further, a method of manufacturing a device according to the present invention includes the steps of: (1-2) manufacturing a device using the projection exposure apparatus according to any one of (1-1) to (1-1-3); And the like.

Further, according to the present invention, there is provided a binary optics element comprising: (1-3) a binary optics element which forms a predetermined phase distribution function by approximating an N-stage (N ≧ 2) staircase structure; The shape of the staircase is shifted from the predetermined phase distribution function depending on the region, and the amplitude transmittance of a light beam passing through the region is changed.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a diffractive optical element according to the present invention will be described. Figure 1 is a diagram of a phase distribution function P ₁ of the virtual lens (elements). The horizontal axis in FIG. 1 is a radial position R with respect to the optical axis O of the element as an origin, and the vertical axis is a phase change φ received when light having a wavelength λ incident on the position R passes through the element. It is. In other words, FIG. 1 shows that the phase of the light of wavelength λ incident on the position R of the optical element is added (changed) by φ.
It shows the relationship of R-φ indicating emission.

An element which causes the same phase change as the phase distribution function P ₁ can perform the same function as the virtual lens. However, since the phase term is a periodic function having a period of 2π in light propagation, the phase distribution function 2 for any value of
A function that adds (or subtracts) an integer multiple of π can perform the same function.

[0020] P ₂ in Figure 2 the optical axis of the phase distribution functions P ₁ in FIG. 1
The phase change at O is 2π, and a phase change of 2π is discontinuously applied at the position r ₁ where the phase distribution function becomes 0, and discontinuous at the position r ₂ where the next phase distribution function becomes 0. Gives the phase change amount of 2π again. .. Is a diagram of a phase distribution function configured so that the phase distribution function falls within 0 to 2π. The function P ₂ has become the basis of the phase distribution plus an integral multiple of 2π the function P ₁ (or subtracting a) function can perform the same action as the element of the phase distribution functions P _1.

Using this property, the phase distribution function shown in FIG.
To prepare a device having a P ₂ may be substituted for the virtual lens of Figure 1, in practice it is difficult to produce a device which gives the phase distribution function P ₂ accurately.

Therefore, in practice, the phase distribution function shown in FIG.
Often by the phase distribution function P ₃ approximating the P ₂ stepwise to prepare an element. An element in which the phase distribution function is approximated stepwise is called a binary optics element, and it is known that it can be easily manufactured by a lithography method or the like.

In this binary optics element, since the original phase distribution function is approximated in a stepwise manner, the difference between the original phase distribution function and the lens having the original phase distribution function is defined as the total amount of light in the direction in which the incident light is deflected by the original lens. Is not deflected, and a part of the light amount is deflected in different directions.

The ratio of (the amount of light deflected in the desired direction: the total amount of incident light) is called the diffraction efficiency. The diffraction efficiency K of the binary optics element is related to the number N of steps at the time of approximating the phase distribution function,

[0025]

(Equation 1) It is represented by

From equation (1), for example, when N = 2, K = 0.40
5, K = 0.684 for N = 3, K = 0.811 for N = 4, N = 8
In the case of, it can be seen that K = 0.950. However, these values are the efficiency of the intensity, and the efficiency S as the amplitude is the square root of the diffraction efficiency K. Therefore, when N = 2, S = (0.405)
^1/2 = 0.636, if N = 3, S = (0.684) ^1/2 = 0.827, N = 4
For S = (0.811) ^1/2 = 0.901, For N = 8 S = (0.95
0) ^1/2 = 0.975. These values represent the amplitude of the first-order diffracted light when the amplitude of the light beam incident on the binary optics element is set to 1.

Therefore, even if the phase distribution function is originally the same, if the number N of steps at the time of approximation is different, the amplitude of the deflected light beam will be different even if the amplitude of the incident light beam is equal. Furthermore, if the number N of the steps is changed depending on the region within the element, it can be seen that the amplitude of the light flux deflected for each region on one element is different, that is, the element can have different amplitude transmittance. At this time, the remaining amplitude becomes the amplitude of the light beam deflected in another direction, and almost no absorption occurs.

FIG. 3 is a sectional view of Embodiment 1 of the binary optics element of the present invention. This embodiment has a diameter of 2r (mm)
Is manufactured as a binary optics element. The binary optics element 20 has a radius
Region 4 of 0.8r to 1.0r (mm) and region of radius 0.0r to 0.8r (mm)
5 and the number of steps N in the area 4 is 2
The number of steps N in the step and the area 5 is eight.

In this case, the transmittance S of the amplitude in the region 4 is equal to 0.
Since S = 0.975 in region 5 and S = 0.975 in region 5, the relative amplitude transmittance in region 4 is 0.636 / 0.975 = 0.652. Therefore, this binary optics element 20 can be considered as an element in which only region 4 has an amplitude transmittance of 0.652.

According to the above configuration, the diffraction efficiency is low in the region where the approximation accuracy of the phase distribution function is low, and the diffraction efficiency is high in the region where the approximation accuracy is high. As a result, a binary optics element having regions with different transmittances can be obtained.

FIG. 4 shows a first embodiment of a projection exposure apparatus according to the present invention.
FIG. This embodiment is a projection exposure apparatus in which an annular light source is used as a light source, and a binary optics element 20 shown in FIG. 3 is inserted into a pupil plane of a projection optical system.

In the drawing, reference numeral 6 denotes a ring-shaped annular light source. 7
Denotes a mask on which a pattern (first object) 7A to be reduced and projected onto the wafer by a projection optical system is formed. 10A is a first lens group, and 10B is a second lens group. Reference numeral 20 denotes the binary optics element (diffractive optical element) in FIG. The first lens group 10A, the binary optics element 20, the second lens group 10B, and the like constitute one element of the projection optical system 10. The binary optics element
Numeral 20 is arranged near the aperture stop of the projection optical system 10. Reference numeral 11 denotes a wafer (a second object).

FIG. 5 is a plan view of the annular light source 6. The annular zone light source 6 has a maximum radius of 1
Emits light only in the annular zone having a radius of 0.8 to 1.0. Therefore, the annular light source 6 is located away from the optical axis of the illumination optical system (not shown).

The operation of this embodiment will be described. Annular light source 6
The light emitted from is patterned by an illumination optical system (not shown)
The pattern 7A is illuminated obliquely with a predetermined angle, and the pattern 7A is illuminated obliquely. The light beam emitted from the pattern 7A forms an image on the wafer 11 via the projection optical system 10 to form a reduced image of the pattern 7A on the wafer 11.

At this time, when the radius of the pupil (aperture of the aperture stop) of the projection optical system 10 is r (mm), the relative amplitude transmittance of the annular light source 6 on the binary optics element 20 is 0.652. An image is formed on the area 4. Therefore, 0 from the object
The second-order diffracted light 8 passes through the region 4 where the relative amplitude transmittance is 0.652 when passing through the binary optics element 20 on the pupil plane, and is involved in the subsequent image formation.

The pattern 7A is a periodic pattern in which the widths of the light transmitting portion and the light shielding portion are equal, and the binary optics device 20
If there is no, the amplitude of the 0th-order diffracted light 8: the amplitude of the 1st-order diffracted light 9 = 1: 2 / π = 1: 0.
In the present embodiment, the ratio is (1 × 0.652) :( 2 / π) = 0.652: 0.636 = 1 because the amplitude of the zero-order diffracted light 8 is reduced by the region 4 of the binary optics element 20 in the present embodiment. : 0.976, which is close to 1. As a result, the contrast of the image formed on the wafer 11 is improved.

In the above-mentioned Japanese Patent Application Laid-Open No. 5-41345, an image is formed with good contrast up to a narrow line width by setting the transmittance of an area where the light source forms an image on the pupil plane to 0.2 to 0.6. It is stated that when the transmittance is in the range of 0.3 to 0.5, the contrast of the image is significantly improved.

In this embodiment, the relative amplitude transmittance in the region where the light source forms an image is 0.652, which is slightly larger than the appropriate transmittance 0.2 to 0.6 shown in the above-mentioned publication. The transmittance is further reduced from 0.652 to 0.2 to 0.6.
May be further reduced by lowering the approximation accuracy of the phase distribution function.

In the above-described binary optics element 20, the amplitude transmittance of each area is controlled by controlling the number of steps in each area. However, by shifting the shape of the step of the binary optics element from an ideal one (approximation). The amplitude transmittance can be controlled (by reducing the precision of the amplitude). This will be described.

FIG. 6 is an explanatory diagram of a phase distribution function deviated from an ideal step shape with two stages. In the case where the number of stages is 2, there are a stage having a phase of 0 and a stage having a phase of π during one cycle, but the ideal step shape here means that the width of the stage of phase 0 and the width of the phase of phase π are T / 2 means the same shape. That is, one cycle
T, and the width of the phase 0 phase is (1 + a) T / 2, which is the case of a = 0, and is indicated by a broken line in FIG. On the other hand, the case of deviation from the ideal staircase shape refers to a shape in which the width of the stage of phase 0 and the stage of phase π are different during one cycle, and a is 0.
It corresponds to cases other than. In FIG. 6, the solid line shows the shape when a> 0.

The diffraction efficiency K in the equation (1) is obtained when the steps are ideally shaped. When the number of steps is N = 2,

[0042]

(Equation 2) Becomes

On the other hand, the diffraction efficiency K when the stairs deviate from the ideal shape is calculated by K = cos ² (πa / 2) × (4 / π ² ). This equation is (4 / π ² ) when a = 0, so the diffraction efficiency K = (4 / π ² ) of the ideal step shape according to the deviation a includes the case of the ideal step shape. To cos ² (πa / 2)
Is considered to be a factor.

Here, the transmittance of the amplitude can be considered again as the square root of the diffraction efficiency, so that the transmittance of the amplitude is p (a) = | co
s (πa / 2) | The range of p (a) is
Since there is [0,1], the value of a is appropriately determined between 0 and 1 so that {0 to the amplitude transmittance (0.65
2)}, a desired transmittance can be obtained.

For example, in the above example, if a = 1/2 in the region 4 formed with the number of steps N = 2, p (1/2) = 0.707, and the relative transmittance of the region 4 is 0.652 × 0.707. = 0.461
Becomes This is in the range of transmittance showing a remarkable effect for improving the contrast.

FIG. 7 shows a second embodiment of the projection exposure apparatus of the present invention.
FIG. In the present embodiment, a quadrupole light source is used as a light source, and a high-resolution and high-contrast projection exposure apparatus is formed by an oblique incidence illumination method using an appropriate binary optics element.

This embodiment differs from the first embodiment of the projection exposure apparatus only in the light source and the binary optics element, and the other parts are the same.

FIG. 8 is a plan view of the quadrupole light source 12 used in this embodiment. This light source also forms an image near the pupil (aperture stop) of the projection optical system 10, and the figure is represented by pupil coordinates.
This light source has light-emitting portions at four positions away from the optical axis of an illumination optical system (not shown).

FIG. 9 is a perspective view of a binary optics element (diffractive optical element) 21 used in this embodiment. The radius of the binary optics element 21 is equal to the radius of the pupil (the aperture of the aperture stop) of the projection optical system 10, and is on the pupil plane, that is, the area where the image of the quadrupole light source 12 is formed by the zero-order light on the binary optics element 21. Only 14 are manufactured with the number of steps N = 2. The other region 13 is manufactured with the number of steps N = 8.

Assuming that these staircase shapes are ideal, in a region 14 where the number of steps is N = 2, the diffraction efficiency K = 0.
405, the transmittance S of the amplitude is (0.405) ^1/2 = 0.636, and similarly, the transmittance S of the amplitude of the region 13 having the number of stages N = 8 is (0.95).
50) ^1/2 = 0.975, so that the amplitude transmittance when the 0th-order diffracted light 8 of the object passes through the binary optics element 21 is 0.
636, the amplitude transmittance when the first-order diffracted light 9 is transmitted is 0.9
75.

When the pattern 7A is a periodic pattern in which the widths of the light transmitting portion and the light shielding portion are equal, the ratio of the amplitudes of the 0th-order diffracted light 8 and the 1st-order diffracted light 9 before entering the binary optics element 21 is 1: 2 / π = 1: 0.636, but passing through the binary optics element 21, the 0th-order diffracted light 8 and the 1st-order diffracted light
The ratio of the amplitude to 9 is improved to (1 × 0.636) :( 2 / π × 0.975) = 1: 0.976, and the image contrast can be improved compared to the case where the binary optics element 21 is not used. .

In each of the above embodiments of the projection exposure apparatus, an image of the zero-order light of the light source is formed in the area around the aperture of the aperture stop of the projection optical system, and an image of the light source with the first-order diffracted light is formed in other areas. When forming and increasing the resolving power of the projection optical system, a binary optics element is provided at the position of the aperture stop, and the number of steps of the stairs is changed according to the image region of the 0th-order light and the 1st-order diffracted light of the light source in the binary optics element. Alternatively, the accuracy of the approximation of the phase distribution function is changed by shifting the shape of the stairs from the predetermined phase distribution function, thereby adjusting the amplitude transmittance of the light beam passing through each region, thereby achieving the original purpose of the binary optics element. In addition to the light deflection, the contrast of the image of the projection optical system is improved.

The binary optics element of the present invention can also play an important role in constituting a projection optical system having a high resolution. This will be described.

As another method of giving a high resolution to a projection exposure apparatus, there is a method of shortening the wavelength of exposure light. The mainstream of the 64MDRAM generation is the i-line of a mercury lamp (wavelength λ = 365nm), but the resolution of the lens is proportional to the wavelength.
It is effective to shorten the wavelength of the m, ArF excimer laser to λ = 193 nm. Comparing the optical system with the same aperture ratio and the same projection magnification, the resolution line width of the optical system of the KrF excimer laser is i
This is because it is 0.68 of that of the line optical system, and the resolution line width of the ArF excimer laser optical system is 0.53 that of the i-line optical system.

However, since it is difficult to narrow the wavelength band of these lasers, it is necessary to achromatize the projection optical system satisfactorily. However, glass materials that transmit light in the ultraviolet region are limited. Therefore, it is difficult to achromatize a lens using a concave lens and a convex lens.

At the same time, since the transmittance is low in this wavelength range, it is necessary to keep the total thickness of the glass material of the lens small, which also impedes the lens design.

The above two problems can be solved by using a diffractive optical element as described above. That is, the diffractive optical element has a wavelength dispersion opposite to that of the refractive optical element (normal lens),
In addition to effectively acting on the achromatism of the lens, the thickness can be reduced, so that both the achromatism of the projection optical system and the reduction of the total glass material thickness can be solved.

When the binary optics element of the present invention is applied to a projection exposure apparatus for forming a fine pattern, it can play two roles of a light deflecting element and a transmittance adjusting element. The effect of achromatizing the optical system can be provided, and a reduction in the total glass material thickness and an effect of achromatizing can also be expected.

FIG. 10 is a schematic view of a main part of a semiconductor device manufacturing system using the first embodiment of the projection exposure apparatus. This system is a system for manufacturing a semiconductor device by printing a circuit pattern provided on an original plate such as a reticle or a photomask on a wafer. The system roughly includes a projection exposure apparatus, a mask storage apparatus, a mask inspection apparatus, and a controller, which are arranged in a clean room.

Referring to FIG. 9, reference numeral 920 denotes the first embodiment of the projection exposure apparatus.

Reference numeral 914 denotes a storage device for the original plate (mask),
Multiple original plates are stored inside. An inspection device 913 detects the presence or absence of foreign matter on the mask. This inspection device 913
Performs a foreign substance inspection on the mask 7 before the selected mask 7 is pulled out of the storage device 914 and set at the exposure position of the projection exposure apparatus.

Reference numeral 918 denotes a controller which controls the sequence of the entire system.
An operation command of 913 and each part of the projection exposure apparatus 920 are controlled to control a sequence of basic operations such as alignment, exposure, and step feed of a wafer.

Reference numeral 900 denotes an alignment system which detects a deviation in the relative position between the mask 7 and the wafer 11 prior to the exposure operation and matches the relative position via the stage 911. The alignment system 900 has at least one microscope system for observing a mask. 902 is a unitized lighting system,
The mask 7 is illuminated by changing the light from the annular light source 12 into a predetermined obliquely incident illumination light beam.

Hereinafter, a manufacturing process of a semiconductor device using the present system will be described.

FIG. 11 is a flowchart showing the steps of manufacturing semiconductor devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, and CCDs). This will be described. Step 1 (Circuit design): Design circuits for semiconductor devices. Step 2 (mask production): A mask 7 having a designed circuit pattern is produced. Step 3 (wafer manufacturing): A wafer is manufactured using a material such as silicon. Step 4 (wafer process): This step is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask (reticle) 7 and wafer 11. Step 5 (assembly): This step is called a post-process, and is a step of forming chips using the wafer created by step 4, and includes steps such as an assembly step (dicing and bonding) and a packaging step (chip enclosing). including. Step 6 (inspection): An inspection such as an operation confirmation test and a durability test of the semiconductor device created in Step 5 is performed. Step 7 (shipment): The semiconductor device is completed and shipped.

FIG. 12 is a detailed flowchart of the above wafer process. This will be described. Step 11 (oxidation): The surface of the wafer is oxidized. Step 12 (CVD): An insulating film is formed on the surface of the wafer. Step 13 (electrode formation): An electrode is formed on the wafer by vapor deposition. Step 14 (ion implantation): Ions are implanted into the wafer. Step 15 (resist processing): resist on wafer (sensitive material)
To form a photosensitive substrate. Step 16 (exposure): mask 7 using projection exposure apparatus 920
The reduced image of the circuit pattern is exposed on the wafer 11. Step 17 (development): The exposed wafer 11 is developed. Step 18 (etching): Strip off the area other than the developed resist. Step 19 (resist removal): Remove unnecessary resist after etching.

As shown in the figure, a circuit pattern is formed on the wafer by repeating these steps.

The exposure step of step # 16 will be described in more detail. In the projection exposure apparatus of FIG.
The mask 7 to be used is taken out from 4 and set in the inspection device 913.

Next, a foreign substance on the mask 7 is inspected by the inspection apparatus 913. If the inspection shows that there are no foreign objects,
This mask is set at the exposure position of the projection exposure apparatus 920.

Next, the wafer 11 as an object to be exposed is set on the stage 911. The stage 911 is stepped by the step & repeat method, and the alignment system 90
With 0, the mask (reticle) 7 and the wafer 11 are aligned (aligned), and the pattern of the mask is reduced, projected and exposed. This operation is repeated.

When the entire surface of one wafer 11 has been exposed,
A new wafer is supplied while accommodating this, and the exposure of the pattern of the mask 7 is repeated in the same manner by the step & repeat method.

The exposure process is completed as described above, and the exposed wafer 11 having been exposed is sent to the next development process.

According to the present system using the projection exposure apparatus of the present invention, the performance of the optical system is not degraded and a high resolution is exhibited. Therefore, a highly integrated circuit having a very fine circuit pattern which has been difficult to manufacture conventionally. Semiconductor devices can be manufactured.

[0074]

According to the present invention, the amplitude transmittances of the zero-order light and the high-order diffracted light from the object are adjusted independently of light absorption when solving the problem of the oblique incidence illumination method. To achieve a projection exposure apparatus that does not change the imaging characteristics of the projection optical system even when operated for a long time, and is stable, has high resolution and high contrast, and exhibits high performance especially when an excimer laser is used as a light source. .

Further, by using the projection exposure apparatus of the present invention, there is provided a device manufacturing method capable of obtaining a high resolution without deteriorating the performance of an optical system and capable of manufacturing a highly integrated semiconductor device which has conventionally been difficult to manufacture. To achieve.

Further, according to the present invention, it is possible to achieve a binary optics device in which the amplitude transmittance differs depending on the region and the light absorption is extremely small.

[Brief description of the drawings]

FIG. 1 is a diagram of a phase distribution function P ₁ of a virtual lens.

Figure 2 shows a phase distribution function P ₃ approximate to the range of the phase distribution functions [0,2] and the phase distribution function P ₂ and stepped

FIG. 3 is a sectional view of an embodiment of the diffractive optical element of the present invention.

FIG. 4 is a schematic view of a main part of a projection exposure apparatus according to a first embodiment of the present invention.

FIG. 5 is a plan view of the annular light source according to the first embodiment of the projection exposure apparatus.

FIG. 6 is an explanatory diagram of a binary optics element having two stages

FIG. 7 is a schematic view of a main part of a projection exposure apparatus according to a second embodiment of the present invention.

FIG. 8 is a plan view of a quadrupole light source according to a second embodiment of the projection exposure apparatus.

FIG. 9 is a perspective view of a diffractive optical element according to a second embodiment of the projection exposure apparatus.

FIG. 10 is a schematic diagram of a main part of a semiconductor device manufacturing system using the projection exposure apparatus according to the first embodiment of the present invention.

FIG. 11 is a flowchart of a semiconductor device manufacturing process.

FIG. 12 is a detailed flowchart of a wafer process.

FIG. 13 is a schematic view of an optical system of a conventional projection exposure apparatus.

FIG. 14 is an explanatory view of a light source and an annular filter of a conventional projection exposure apparatus.

[Explanation of symbols]

P ₁ : Phase distribution function P ₂ : Phase distribution function convolved with [0,2π] P ₃ : Phase distribution function approximated stepwise 4: Area 5: Area 6: annular light source 7: Mask 7A: Pattern ( 8) Zero-order diffracted light from the object 9: 1st-order diffracted light from the object 10: Projection optical system 10A: First lens group 10B: Second lens group 11: Wafer 12: Quadrupole light source 13: Area 14 : Region 20,21: Binary optics element (diffractive optical element)

Claims (6)

[Claims] An illumination optical system converts light from a light source into a predetermined illumination light beam to illuminate a first object, and projects and exposes the first object onto a second object by a projection optical system. In a projection exposure apparatus, a predetermined phase distribution function is provided at a position of an aperture stop of the projection optical system.
A binary optics element approximated by an N-stage (N ≧ 2) staircase structure is arranged, the light source is imaged on the binary optics element, and a region of an image of the light source on the binary optics element with zero-order light is arranged. The amplitude transmittance of the other region and the amplitude transmittance of the other region are controlled by changing the number of steps of the step or by shifting the shape of the step from the predetermined phase distribution function. Exposure equipment. 2. The projection exposure apparatus according to claim 1, wherein an area of an image formed by the zero-order light of the light source on the binary optics element is located away from an optical axis of the projection optical system. . 3. An amplitude transmittance of an area of an image due to zero-order light of the light source on the binary optics element is lower than an amplitude transmittance of the other areas. Projection exposure equipment. 4. The projection exposure apparatus according to claim 1, wherein the light source is located apart from an optical axis of the illumination optical system. 5. A device manufacturing method, comprising manufacturing a device using the projection exposure apparatus according to claim 1. Description: 6. A binary optics element that forms a predetermined phase distribution function by approximating an N-step (N ≧ 2) staircase structure, wherein the shape of the staircase is determined by an area in the binary optics element. A binary optics element that varies the amplitude transmittance of a light ray passing through the region, deviating from a function.