JP2006173309A - Projection aligner, position measuring method, and projection exposure method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of stably and accurately measuring the position of an object under exposure to its uppermost without subjecting to the change of the surface film thickness and film quality condition. <P>SOLUTION: The aligner comprises a first and a second liquid storing tanks 26, 28, position measuring mechanisms 31, 32 for measuring the surface height of an object under exposure 10, by reflecting a detection light incident on the object surface through a first liquid 4 stored in the first tank from the object surface after covering the object surface with the first liquid 4; and an exposure mechanism for irradiating the object with an exposing light through a second liquid 39 stored in the second tank 28 after covering the object surface with the second liquid 39. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a projection exposure apparatus, a position measurement method, and a projection exposure method, and more particularly, to a projection exposure apparatus, a position measurement method, and a projection exposure method suitable for use in a fine pattern forming process such as a semiconductor integrated circuit device.

  In the manufacture of a semiconductor integrated circuit device or the like, photolithography is performed when a circuit pattern is formed on the surface of a substrate (hereinafter also referred to as “wafer”). This is done by applying a photoresist (photosensitive agent) to the wafer surface, exposing the photoresist (hereinafter also simply referred to as “resist”) by irradiating the light emitted from the light source through a reticle, and developing the photoresist. Forming a mask.

  Examples of the exposure method in photolithography include “contact exposure method”, “reduction projection exposure method”, and “reflection projection exposure method”. Of these, the reduction projection exposure method is widely used.

In recent years, semiconductors have been highly integrated, circuit pattern dimensions have become increasingly finer, and semiconductor structures have become three-dimensional and the manufacturing process has become increasingly complex. For this reason, in lithography (particularly, the reduction projection exposure method and the reflection projection exposure method), it is indispensable to increase the pattern resolution. In order to increase the pattern resolving power, it is necessary to shorten the wavelength of the exposure light and increase the NA (numerical aperture) of the lens according to the following equation (3).

Pattern resolving power≈K ₁ × (exposure light wavelength λ / NA) K ₁ : constant (3)

Since a lens with a high NA is used to form a fine pattern, and the NA of the lens increases, the depth of focus (DOF) decreases rapidly (equation (4) below). In order to form the shape stably, the distance between the lens and the substrate surface must be kept accurately. For this purpose, it is necessary to accurately measure the distance between the lens and the substrate surface.

DOF≈K ₂ × (exposure light wavelength λ / NA ² ) K ₂ : constant (4)

As a method for measuring the distance between the lens and the substrate surface, for example, P-polarized light is used as incident light, and the incident light is applied onto a substrate such as Si (silicon) so that the incident angle becomes a Brewster angle. It is disclosed that the characteristic of a thin film such as a resist is measured by detecting a change in the amount of light incident on and reflected from the resist (see, for example, Patent Document 1).

  FIG. 6 is a schematic diagram showing a position measuring method studied by the inventor in the course of reaching the present invention. That is, FIG. 6 is a schematic cross-sectional view showing a method for measuring the position of the surface of the object to be exposed in the projection exposure apparatus studied in the course of reaching the present invention. As a method for measuring the distance between the lens and the surface of the substrate, as shown in FIG. 6A, the detection light L for position measurement is applied to the surface of the exposure object 1000 in which a resist 300 or the like is applied on the substrate 100. Are made incident at an incident angle θ. Here, the surface of the object 1000 is exposed to the atmosphere. By measuring the light intensity distribution of the reflected light of the detection light L, the return point A of the detection light L is determined. From the position of the return point A, the position (height) of the exposure object 1000 is calculated. And according to the obtained measured value, the position of the to-be-exposed object 1000 is changed, and the to-be-exposed object 1000 is installed in the optimal distance with respect to a lens.

In normal lithography, as shown in FIG. 6, a resist 300 is often applied to the surface of the substrate 100. In such a case, it is necessary to accurately measure the position of the surface of the resist 300.
The method disclosed in Patent Document 1 described above is a technique for measuring the characteristics of a thin film by causing P-polarized light to enter the thin film without reflecting it on the surface of the thin film such as a resist. The premise is different from that of the present invention aiming at total reflection of light.
JP-A-6-84743

  However, the refractive index of the resist 300 is about 1.6, which is close to the refractive index (about 1) of the air 200, so that the total reflection of the detection light L hardly occurs at the interface between the resist 300 and the air 200. . That is, as shown in FIG. 6A, part or all of the detection light L is transmitted through the resist 300, and the detection light L is reduced to point B. As a result, it becomes impossible to know the exact position (height) of the object 1000 to be exposed.

  Further, as illustrated in FIG. 6B, the detection light L transmitted through the resist 300 may be reflected multiple times within the resist 300, and the detection light L may be reduced to a point C or a point D. When the detection light L undergoes multiple reflections, the return points C and D vary depending on the film quality and film thickness of the resist 300. Further, the light intensity of the reflected light of the detection light L at the return points C and D also varies.

FIG. 7 is a schematic view illustrating an exposure apparatus studied by the inventor in the course of reaching the present invention. As shown in the figure, the exposure apparatus 2000 examined by the inventor in the course of reaching the present invention includes a stage 210 on which an object to be exposed 1000 is placed, a height detection unit provided on the stage 210, and a stage 210. And an exposure optical system unit provided at the second location.
The height detection unit includes a light emitting unit 310 provided at a predetermined distance on the stage 210 and a light receiving unit 320 provided at a predetermined distance on the stage 210.

  The exposure optical system unit includes a light source 360 that emits exposure light 350, a mask 370, and a reduction projection lens 380.

  First, the position of the exposure object 1000 is accurately measured by the height detection unit. That is, the object to be exposed 1000 is placed on the stage 210, the detection light L is irradiated from the light emitting unit 310 onto the surface of the object to be exposed 1000, and the detection light L totally reflected by the surface of the object to be exposed 1000 is received by the light receiving unit 340. By detecting, the position (height) of the surface of the exposure object 1000 is accurately measured.

  Next, a predetermined mask pattern is projected and exposed on the object 1000 by the exposure optical system unit. That is, the position of the stage 210 is moved up and down to the optimum height based on the measurement value obtained by the height detection unit 0. At this time, the position of the exposure optical system unit is fixed, and the stage 210 is adjusted by moving up and down so that the imaging surface comes to the surface of the object to be exposed 10. Next, the exposure light 350 is irradiated through the mask 370 and the reduction lens 380 onto the surface of the object 1000 to be exposed.

However, in the exposure apparatus examined by the inventor in the course of reaching the present invention, when the wavelength of the detection light L is about 800 nm, the measured value of the position of the object to be exposed 1000 for the reason described with reference to FIG. There is also an experimental result that fluctuates by about 50 nm.
Thus, when position measurement is performed in a state where the surface of the exposure object 1000 is exposed to the air 200, the detection light L is transmitted through the resist 300, or multiple reflection is caused in the resist 300.
There has been a problem that the exact position (height) of the object to be exposed 1000 cannot be known.
As a result, the distance between the lens and the substrate surface cannot be accurately maintained in the exposure apparatus, and the substrate surface cannot be stably held on the imaging surface. Exposure characteristics will deteriorate.
Under such circumstances, in a method in which light is applied obliquely on the substrate and the position where the reflected light returns from the surface is measured and the distance is measured by the change, the light is applied to a film such as a resist coated on the surface of the substrate. It is necessary to develop a technique for accurately measuring the distance between the lens and the surface of the object to be exposed by totally reflecting light at the outermost surface without entering.

  The present invention has been made on the basis of recognition of such problems, and the object thereof is not affected by changes in the film thickness and film quality of the surface film of an object to be exposed in a photolithography exposure process of a semiconductor device. Provides a position measurement method that can stably and accurately measure the distance to the outermost surface, and by using this method, exposure is performed while holding the substrate accurately at the imaging position. It is an object of the present invention to provide a projection exposure apparatus, a position measuring method, and a projection exposure method capable of accurate pattern transfer.

In order to achieve the above object, according to one aspect of the present invention,
A first liquid storage tank;
A second liquid storage tank;
The surface of the object to be exposed is covered with a first liquid stored in the first liquid storage tank, and detection light is incident on the surface of the object to be exposed through the first liquid, and the object to be exposed A position measurement mechanism that measures the height of the surface of the object to be exposed by reflecting the detection light on the surface of
An exposure mechanism that covers the surface of the object to be exposed with a second liquid stored in the second liquid storage tank, and exposes the object to be exposed by irradiating exposure light through the second liquid; ,
A projection exposure apparatus is provided.

  Here, the position of the surface of the object to be exposed is measured by the position measuring mechanism in a state where the object to be exposed is placed on the stage of the exposure apparatus, and the optical condition is adjusted based on the result to adjust the optical condition. Thus, the exposure can be performed.

  Further, the height measurement by the position measurement mechanism and the exposure by the exposure mechanism may be performed at different locations of the object to be exposed.

  Alternatively, the apparatus may further include a substrate stage on which the object to be exposed is placed, and the substrate stage is movable between the position measurement mechanism and the exposure mechanism. .

  On the other hand, according to another aspect of the present invention, the surface of the object to be measured is covered with a substance having a refractive index higher than the refractive index for the measurement light of the uppermost layer of the object to be measured, and the incident angle larger than the critical angle. The measurement light for distance measurement is incident on the surface of the measured object through the substance, and the measurement light is totally reflected on the surface of the measured object to measure the position of the surface of the measured object. A position measuring method is provided.

  According to yet another aspect of the present invention, the surface of the object to be measured is covered with a substance, and measurement light for distance measurement is incident on the surface of the object to be measured through the substance at an incident angle θ. A measurement method for measuring the position of the surface of the measurement object by detecting the measurement light reflected on the surface of the measurement object, the incident angle θ of the measurement light, and the measurement light of the substance The relationship defined by the following equations (1) and (2) is established between the refractive index na at the wavelength of n and the refractive index nr at the wavelength of the measurement light of the uppermost layer of the object to be measured. A position measuring method is provided.

sinθ> nr / na (1)
nr <na (2)
Here, the substance may be diiodomethane (CH ₂ I ₂ ), 1-bromonaphthalene (1-Bromo Napthalene: C ₁₀ H ₇ Br), or a mixture thereof.
Further, the uppermost layer of the object to be measured can include a photoresist.
According to still another aspect of the present invention, the position of the surface of the measurement object is measured by any one of the above-described position measurement methods in a state where the measurement object is placed on the stage of the exposure apparatus. The projection exposure method is characterized in that the exposure is performed by adjusting the optical conditions based on the result.

Here, the exposure may be performed with the surface of the object to be measured covered with the substance.
Further, the exposure may be performed in a state where the substance is removed from the surface of the object to be measured.

  According to the present invention, the surface of the object to be exposed is covered with a substance having a refractive index higher than that of the uppermost layer film of the object to be exposed, and the detection light for position measurement is irradiated at an incident angle larger than the critical angle. Therefore, the detection light causes total reflection on the surface of the object to be exposed, and light does not enter the lower layer, so that intra-film multiple interference does not occur. Therefore, stable reflection of detection light is obtained without being affected by changes in the film thickness and film quality of the surface of the object to be exposed, and the accuracy of measurement values is improved.

  In addition, according to the present invention, the surface position of the object to be exposed can be stably moved to the imaging plane by measuring the substrate distance by the above-described position measuring method and performing exposure at the same place, and as a result, Variations in the size and shape of the projection pattern are reduced. When the surface of the object to be exposed is covered with a substance having a high refractive index, it is effective when the NA of the exposure optical system is not relatively high and the reflection of exposure light on the substrate surface does not affect the projection image. It is possible to expose with high dimensional accuracy without causing deterioration of contrast.

  Further, according to the present invention, exposure is performed in a state where a material having a high refractive index is removed, the NA of the exposure optical system is extremely high, and the contrast of the projected image is greatly deteriorated due to reflection of the exposure light on the substrate surface. It is effective in the case. By providing a distance detection light optical system at a different location from the exposure optical system and acquiring the substrate distance data in advance, there is no substance A having a high refractive index at the time of exposure. The exposure can be performed without any influence.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to these drawings.
FIG. 1 is a schematic cross-sectional view illustrating the main part of a projection exposure apparatus according to an embodiment of the present invention.

  That is, FIG. 1 is a schematic cross-sectional view showing a method for measuring the position of the surface of an object to be exposed in the projection exposure apparatus according to the present embodiment.

As shown in FIG. 1A, the surface of the object to be exposed 10 on which the resist 3 or the like is applied on the substrate 1 is filled with the high refractive index material 4. Then, the detection light L for position measurement is incident on the object to be exposed 10 at an incident angle θ.
Here, as the high refractive index material 4, a material having a refractive index such that the detection light L causes total reflection on the surface of the object to be exposed 10 is used. Further, the incident angle θ of the detection light L is set larger than the critical angle.

  That is, in order to totally reflect the detection light L on the surface of the object to be exposed 10, the incident angle θ of the detection light L, the refractive index na at the wavelength of the detection light L of the high refractive index substance 4, and the object to be exposed 10. The relationship defined by the following formulas (1) and (2) may be established between the refractive index nr at the detection light wavelength of the uppermost layer of the film.

sinθ> nr / na (1)
nr <na (2)
In the case of nr ≧ na (nr / na ≧ 1), that is, when the refractive index for the measurement light of the high refractive index material 4 is lower than the refractive index for the measurement light of the uppermost layer film of the object to be exposed 10, the equation (1) is Since it is not satisfied, total reflection does not occur. Further, when sin θ ≦ nr / na, that is, when the incident angle θ is smaller than the critical angle, total reflection does not occur.

As the high refractive index substance 4, any substance such as gas or liquid can be used as long as its refractive index na is larger than the refractive index nr of the uppermost film of the object 10 to be exposed. For example, when the uppermost layer 3 of the object to be exposed 10 is made of a resist, the high refractive index material 4 may be diiodomethane (CH ₂ I ₂ , na = 1.741), 1-bromonaphthalene (1-Bromo Napthalene). : C ₁₀ H ₇ Br, na = 1.66), or a mixture thereof. These are convenient in that they have a refractive index higher than that of the resist 3 (about 1.6) and are easy to handle. The high refractive index substance 4 may be any substance such as gas or liquid.

  According to this embodiment, the detection light L is not transmitted through the inside of the object to be exposed 10 but is totally reflected by the surface of the object to be exposed 10. Then, the return point A of the detection light L is determined by measuring the light intensity distribution of the reflected light of the detection light L. From the position of the return point A, the position (height) of the object to be exposed 10 is calculated. And according to the obtained measured value, the position of the to-be-exposed body 10 is changed in the vertical direction, and the lens and the to-be-exposed body 10 are installed at an optimum distance.

  FIG. 1B is a graph showing the light intensity distribution in the vicinity of the return point A of the reflected light of the detection light L. From this figure, the position of the return point A of the reflected light of the detection light L can be known.

  As described above, in this embodiment, the surface of the object to be exposed 10 is filled with the high refractive index substance 4 so that the detection light L is not transmitted through the inside of the object to be exposed 10, and the entire surface of the object to be exposed 10 is exposed. Can be reflected. Therefore, transmission of the detection light L to the lower layer and in-film multiple interference can be prevented. As a result, the return point A of the reflected light of the detection light L can be determined without being affected by changes in the film quality and film thickness of the lower layer, and the position of the object to be exposed 10 can be accurately measured.

  Therefore, the distance between the lens and the surface of the object to be exposed can be accurately maintained, and the surface of the object to be exposed can be stably held on the imaging surface, so that the dimension and shape of the projection pattern are stabilized. As a result, a high-performance projection exposure method can be provided.

  Here, the object to be exposed 10 is not limited to the structure described above. For example, the object to be exposed 10 may have a structure in which TARC (Top Anti Reflective Coating) is further added on the resist 3 and a structure in which BARC (Bottom Anti Reflective Coating) is further added in the lower layer.

FIG. 2 is a schematic view illustrating the projection exposure apparatus according to the embodiment of the invention.
In other words, the projection exposure apparatus 20 of the present embodiment includes a stage 21 on which the object to be exposed 10 is placed, a height detection unit provided on the stage 21, and an exposure optical system unit.

  The height detection unit includes a light emitting unit 31 provided at a predetermined distance on the stage 21 and a light receiving unit 32 provided at a predetermined distance on the stage 21.

The exposure optical system unit includes a light source 36 that emits exposure light 35 and a reduction projection lens 38. The light emitted from the light source 36 is applied to the object to be exposed 10 provided on the stage 21 through the mask 37 and the reduction projection lens 38.
In addition, a nozzle 33 that supplies liquid to the surface of the exposure target 10 provided on the stage 21 and a nozzle 34 that collects the supplied liquid are provided.
The supply nozzle 33 is connected to the liquid storage tanks 26 and 28, and can selectively supply the liquid stored in these liquid storage tanks 26 and 28 to the surface of the object 10 to be exposed. The liquid storage tank 26 stores the high refractive index substance 4, and the liquid storage tank 28 stores the exposure liquid 39.

The operation of this projection exposure apparatus will be described as follows.
First, the position of the object to be exposed 10 is accurately measured by the height detection unit. That is, the object to be exposed 10 is placed on the stage 21, and then the high refractive index substance 4 stored in the liquid storage tank 26 is supplied from the supply nozzle 33 to the surface of the object to be exposed 10. Subsequently, the detection light L is irradiated from the light emitting unit 31 to the surface of the object to be exposed 10 through the high refractive index substance, and the detection light L totally reflected by the surface of the object to be exposed 10 is detected by the light receiving unit 34. Thus, the position (height) of the surface of the object to be exposed 10 is accurately measured. After the measurement, the high refractive index material 4 is recovered from the recovery nozzle 34.

  Next, a predetermined mask pattern is projected and exposed onto the object to be exposed 10 by the exposure optical system unit. That is, based on the measurement value obtained by the height detection unit, the position of the stage 21 is moved up and down to the optimum height. At this time, the position of the exposure optical system unit is fixed, and the stage 21 is adjusted by moving up and down so that the imaging surface comes to the surface of the object 10 to be exposed. Then, the exposure liquid 39 stored in the liquid storage tank 28 is supplied from the supply nozzle 40 to the surface of the exposure target 10 provided on the stage 21.

  Then, the surface of the object to be exposed 10 is irradiated with exposure light 35 through a mask 37 and a reduction lens 38. The exposure method is not limited to the reduced projection exposure method, and various methods such as a reflection projection exposure method can be employed. After the exposure, the exposure liquid 39 is recovered from the recovery nozzle 41.

  That is, in the projection exposure apparatus according to the present embodiment, the height detection unit 22 and the exposure optical system unit 23 are provided on the stage 20 that can move only in the vertical direction. Then, position measurement and projection exposure are performed at different locations in the object 10 to be exposed.

  In the projection exposure apparatus of the present embodiment, the position measuring method described above with reference to FIG. 1 is adopted, so that the distance between the lens and the substrate can be accurately measured, and a circuit pattern or the like can be formed based on the measured value. The position of the substrate surface can be accurately and stably moved to the imaging plane. As a result, variations in the size and shape of the projection pattern can be reduced and the performance as an exposure apparatus can be improved.

Next, a projection exposure apparatus according to a modification of the present invention will be described.
First, as a first modification, a projection exposure apparatus that performs position measurement and projection exposure at different locations on an object to be exposed will be described.

FIG. 3 is a schematic view illustrating the projection exposure apparatus according to the first modification of the present invention.
As shown in the figure, the projection exposure apparatus 20 according to this variation includes a stage 21 on which the object 10 is placed, a height detection unit 22 provided at a first location on the stage 21, and a stage 21. And an exposure optical system unit 23 provided at the second location above.
FIG. 4 is a schematic cross-sectional view illustrating an enlarged main part of the projection exposure apparatus according to this modification. That is, the drawing shows a cross-sectional structure of the main parts of the height detection unit 22 and the exposure optical system unit 23.

  The height detection unit 22 includes a light emitting unit 31 provided at a predetermined distance on the stage 21 and a light receiving unit 32 provided at a predetermined distance on the stage 21. Moreover, the nozzle 33 which supplies the high refractive index substance 4 on the to-be-exposed body 10 provided on the stage 21 and the nozzle 34 which collect | recovers the high refractive index substance 4 are provided.

  The exposure optical system unit 23 includes a light source 36 (FIG. 3) that emits exposure light 35, a mask 37 (FIG. 4), and a reduction projection lens 38. Furthermore, it has the nozzle 40 which supplies the exposure liquid 39 supplied to the surface of the to-be-exposed body 10 provided on the stage 21, and the nozzle 41 which collect | recovers the exposure liquid 39.

The operation of the projection exposure apparatus of this modification will be described as follows.
First, the position of the object to be exposed 10 is accurately measured by the height detection unit 22. That is, the object to be exposed 10 is placed on the stage 21, and then the high refractive index substance 4 is supplied from the supply nozzle 33 to the surface of the object to be exposed 10. The high refractive index substance 4 is supplied to the first place where the height detection unit 22 is provided in the exposure object 10. At this time, if the arrangement relationship among the light emitting unit 31, the light receiving unit 32, the nozzle 33, and the nozzle 34 is appropriately adjusted, the high refractive index substance 4 is exposed to the member while being in contact with these members by the surface tension as illustrated in FIG. The body 10 is held at a predetermined position. In this state, the detection light L is irradiated from the light emitting unit 31 to the surface of the object to be exposed 10 through the high refractive index substance 4, and the detection light L totally reflected by the surface of the object to be exposed 10 is detected by the light receiving unit 34. By doing so, the position (height) of the surface of the object to be exposed 10 is accurately measured. After the measurement, the high refractive index material 4 is recovered from the recovery nozzle 34.

  Next, the exposure optical system unit 23 projects and exposes a predetermined mask pattern on the object 10 to be exposed. That is, the position of the stage 21 is moved up and down to an optimum height based on the measurement value obtained by the height detection unit 22. At this time, the position of the exposure optical system unit 23 is fixed, and the stage 21 is adjusted by moving up and down so that the imaging surface comes to the surface of the object to be exposed 10. Then, the exposure liquid 39 is supplied from the supply nozzle 40 to the surface of the exposure target 10 provided on the stage 21. Here, the place for supplying the exposure liquid 39 (second place) is different from the height detection place (first place) on the surface of the exposure target 10 provided on the stage 21. Is a place. Next, the surface of the object to be exposed 10 is irradiated with exposure light 35 through a mask 37 and a reduction lens 38. The exposure method is not limited to the reduced projection exposure method shown in FIG. 3, and various methods such as a reflection projection exposure method can be employed. After the exposure, the exposure liquid 39 is recovered from the recovery nozzle 41.

  That is, in the projection exposure apparatus according to this modification, the height detection unit 22 and the exposure optical system unit 23 are provided at different locations on the stage 20 that can move only in the vertical direction. Then, position measurement and projection exposure are performed at different locations in the object 10 to be exposed. As described above, in the projection exposure method provided in a place where the position measuring device and the exposure optical system are different, the NA of the exposure optical system is extremely high, and the contrast of the projected image is greatly deteriorated due to reflection of the exposure light on the substrate surface. It is effective in such cases. A distance detection light optical system is provided at a location different from the exposure optical system, substrate distance data is acquired in advance, and exposure is performed by irradiating the exposure light 35 with the high refractive index substance 4 removed. The exposure can be performed without affecting the contrast of the projected image.

In addition, since position measurement and projection exposure are performed at different locations within the object to be exposed 10, depending on the type of the object to be exposed 10 and the high refractive index substance 4, the high refractive index substance 4 may be removed after the position measurement. Alternatively, the surface of the object to be exposed 10 may be left filled.
When the high refractive index substance 4 is removed for exposure, it is advantageous in that exposure can be performed without being affected by optical influences such as refraction and absorption of exposure light by the high refractive index substance 4.
On the other hand, when the high refractive index substance 4 is exposed while the surface of the object to be exposed 10 is filled, the heat dissipation effect can be enhanced by the high refractive index substance 4. That is, the temperature rise when the exposure light 35 is irradiated to the object to be exposed 10 can be suppressed according to the thermal conductivity of the high refractive index substance 4. As a result, distortion due to thermal expansion, thermal damage / deterioration, and the like can be suppressed.

  Also in the projection exposure apparatus according to this modification, since the position measuring method described above with reference to FIG. 1 is employed, the distance between the lens and the substrate can be measured, and a circuit pattern can be formed based on the measured value. The position of the substrate surface can be stably moved to the image plane, and as a result, variations in the size and shape of the projection pattern can be reduced and the performance as an exposure apparatus can be improved.

Next, a projection exposure apparatus according to a second modification of the present invention will be described.
That is, in the second modification, the position measurement and the projection exposure described above are performed by moving together with the stage 45 on which the object to be exposed 10 is placed.

  FIG. 5 is a schematic view illustrating a projection exposure apparatus according to a second modification of the present invention. As shown in the figure, the projection exposure apparatus 20 according to this modification has a stage 45 on which the object to be exposed 10 is placed. The stage 45 is movable in the horizontal direction. That is, the stage 45 can move to the first place and the second place located at the same height as the first place. The projection exposure apparatus 20 further includes a height detection unit 22 on the stage 45 provided at the first location, and an exposure optical system unit 23 on the stage 45 provided at the second location. Have.

  The height detection unit 22 has the same structure as that of the first embodiment described above. That is, the light emitting unit 31 provided on the stage 45 with a predetermined distance and the light receiving unit 32 provided on the stage 21 with a predetermined distance are provided. Furthermore, a nozzle 33 (not shown) for supplying the high refractive index substance 4 onto the exposure target 10 provided on the stage 21, and a nozzle 34 (not shown) for collecting the high refractive index substance 4. Have.

  The exposure optical system unit 23 also has a structure similar to that of the first modification described above. That is, a light source 36 that emits exposure light 35, a mask 37, and a reduction projection lens 38 are included. Furthermore, a nozzle 40 (not shown) for supplying the exposure liquid 39 supplied to the surface of the object 10 provided on the stage 45, and a nozzle 41 (not shown) for collecting the exposure liquid 39. And having.

  In the projection exposure apparatus according to this modification, first, the stage 45 is installed in a first place where the height detection unit 22 is provided. And the to-be-exposed body 10 is mounted on the stage 45, and the high refractive index substance 4 is supplied to the surface of the to-be-exposed body 10 from the supply nozzle 33 after that. Then, the position of the object to be exposed 10 is accurately measured by the height detection unit 22. The measurement procedure is the same as that of the first modified example described above.

  Next, the stage 45 is moved to the second place where the exposure optical system unit 23 is provided with the object 10 to be exposed placed thereon. Based on the measurement value obtained by the height detection unit 22, the position of the stage 45 is moved up and down to the optimum height. At this time, the position of the exposure optical system unit 23 is fixed, and the stage 45 is adjusted by moving up and down so that the imaging surface comes to the surface of the object 10 to be exposed. Then, the exposure optical system unit 23 projects and exposes a predetermined mask pattern onto the object 10 to be exposed.

  That is, in this modification, position measurement and projection exposure are performed by moving the stage 45 on which the object to be exposed 10 is placed. If it does in this way, position measurement and projection exposure can be performed in the same place in object 10 to be exposed. Therefore, even when the height varies depending on each region in the object to be exposed 10, accurate exposure can be performed without being affected by the difference.

  Further, the projection exposure method in which the position measuring device and the exposure optical system are provided at the same place is effective when the NA of the exposure optical system is relatively high and the reflection of the exposure light on the substrate surface does not affect the projection image. Therefore, exposure can be performed with high dimensional accuracy without causing deterioration of contrast.

  Also in this modified example, since the surface of the object to be exposed 10 is filled with the high refractive index substance 4 and measured at the time of position measurement, accurate position measurement can be performed as described above. As a result, the lens and the object to be exposed 10 can be kept at an optimum distance, and accurate exposure can be performed.

  Next, a projection exposure apparatus according to a third modification of the present invention will be described. That is, in the third modification, position measurement and projection exposure are performed by immersing the object to be exposed 10 in a liquid.

  FIG. 6 is a schematic view illustrating a projection exposure apparatus according to a third modification of the present invention. As shown in the figure, the projection exposure apparatus 20 according to this modification includes a stage 51 provided with a buildup fence 52 on which the object to be exposed 10 is placed. The stage 51 is movable in the horizontal direction. That is, the stage 51 can move to the first place and the second place located at the same height as the first place. Furthermore, a liquid buildup fence 52 is provided on the outer periphery of the upper surface of the stage 51. The projection exposure apparatus 20 further includes a height detection unit 22 on the stage 51 provided at the first location, and an exposure optical system unit 23 on the stage 51 provided at the second location. Have.

  The height detection unit 22 has the same structure as that of the first modification described above. That is, the light emitting unit 31 provided on the stage 51 at a predetermined distance and the light receiving unit 32 provided on the stage 51 at a predetermined distance are provided. Furthermore, a nozzle 33 (not shown) for supplying the high refractive index substance 4 onto the exposure target 10 provided on the stage 51, and a nozzle 34 (not shown) for collecting the high refractive index substance 4. Have.

  The exposure optical system unit 23 also has the same structure as that of the first modification described above. That is, a light source 36 that emits exposure light 35, a mask 37, and a reduction projection lens 38 are included. Further, a nozzle 40 (not shown) for supplying the exposure liquid 39 supplied to the surface of the exposure target 10 provided on the stage 51, and a nozzle 41 (not shown) for collecting the exposure liquid 39. Have.

  In the projection exposure apparatus according to this modification, first, the stage 51 is installed at a first place where the height detection unit 22 is provided. Then, the stage 51 is filled with the high refractive index substance 4 in advance, and the object to be exposed 10 is immersed therein. Then, the position of the object to be exposed 10 is accurately measured by the height detection unit 22. The measurement procedure is the same as that of the first modified example described above.

  Next, the stage 51 is moved to a second location where the exposure optical system unit 23 is provided. Then, the stage 51 is filled with the exposure liquid 39 in advance, and the object to be exposed 10 is immersed therein. The stage 51 on which the object to be exposed 10 is placed is filled with the exposure liquid 39 and moved to a second location where the exposure optical system unit 23 is provided. Based on the measurement value obtained by the height detection unit 22, the position of the stage 51 is moved up and down to the optimum height. At this time, the position of the exposure optical system unit 23 is fixed, and the stage 51 is adjusted by moving up and down so that the imaging surface comes to the surface of the object to be exposed 10. Then, the exposure optical system unit 23 projects and exposes a predetermined mask pattern onto the object 10 to be exposed.

  That is, in this modification, position measurement and projection exposure are performed by moving the stage 51 on which the object to be exposed 10 is placed. Furthermore, the high refractive index substance 4 and the exposure liquid 39 are filled in the stage 51 provided with the flooding fence 52, and the object to be exposed 10 is immersed therein. Then, the height detection unit 22 and the exposure optical system unit 23 are placed therein, thereby performing position measurement and projection exposure.

  Also in this modified example, since the surface of the object to be exposed 10 is filled with the high refractive index substance 4 and measured at the time of position measurement, accurate position measurement can be performed as described above. As a result, the lens and the object to be exposed 10 can be kept at an optimum distance, and accurate exposure can be performed.

The embodiments of the present invention have been described above with reference to specific examples.
However, the present invention is not limited to these specific examples. For example, specific configurations, structures, processes, and the like of the projection exposure apparatus and exposure method used in the present invention are also included in the scope of the present invention as appropriately selected by those skilled in the art.

It is a cross-sectional schematic diagram which illustrates the principal part of the projection exposure apparatus concerning embodiment of this invention. It is a cross-sectional schematic diagram which illustrates the projection exposure apparatus concerning embodiment of this invention. It is a schematic diagram which illustrates the projection exposure apparatus concerning the 1st modification of this invention. It is a schematic diagram which expands and illustrates the principal part of the projection exposure apparatus concerning the 1st modification of this invention. It is a schematic diagram which illustrates the projection exposure apparatus concerning the 2nd modification of this invention. It is a schematic diagram which illustrates the projection exposure apparatus concerning the 3rd modification of this invention. It is a schematic diagram showing the principal part of the exposure apparatus which this inventor examined in the process leading to this invention. It is a schematic diagram showing the exposure apparatus which this inventor examined in the process leading to this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 3 Resist 4 High refractive index substance 10 Object to be exposed 20 Projection exposure apparatus 21 Stage 22 Detection unit 23 Exposure optical system unit 31 Light emission part 32 Light reception part 33 Supply nozzle 34 Recovery nozzle 35 Exposure light 36 Light source 37 Mask 38 Reduction projection Lens 39 Liquid for exposure 40 Supply nozzle 41 Recovery nozzle 45 Stage 52 Flooding fence

Claims (11)

A first liquid storage tank;
A second liquid storage tank;
The surface of the object to be exposed is covered with a first liquid stored in the first liquid storage tank, and detection light is incident on the surface of the object to be exposed through the first liquid, and the object to be exposed A position measuring mechanism that reflects the detection light on the surface of the object and measures the height of the surface of the object to be exposed;
An exposure mechanism that covers the surface of the object to be exposed with a second liquid stored in the second liquid storage tank, and exposes the object to be exposed by irradiating exposure light through the second liquid; ,
A projection exposure apparatus comprising:   With the object to be exposed mounted on the stage of the exposure apparatus, the position measurement mechanism measures the position of the surface of the object to be exposed, and adjusts the optical conditions based on the result, and the exposure mechanism performs the exposure. The projection exposure apparatus according to claim 1, wherein:   The projection exposure apparatus according to claim 1, wherein the height measurement by the position measurement mechanism and the exposure by the exposure mechanism are performed at different locations of the object to be exposed. A substrate stage on which the object to be exposed is placed;
The projection exposure apparatus according to claim 1, wherein the substrate stage is movable between the position measurement mechanism and the exposure mechanism.   The surface of the object to be measured is covered with a substance having a refractive index higher than the refractive index for the measurement light of the uppermost layer of the object to be measured, and the measurement light for distance measurement at an incident angle larger than the critical angle is passed through the substance. A position measuring method, wherein the position is made incident on the surface of the measured object, and the position of the surface of the measured object is measured by totally reflecting the measurement light on the surface of the measured object. Covering the surface of the object to be measured with a substance, causing measurement light for distance measurement to enter the surface of the object to be measured through the substance at an incident angle θ, and reflecting the measurement light reflected on the surface of the object to be measured A measurement method for measuring the position of the surface of the object to be measured by detecting the incident angle θ of the measurement light, the refractive index na of the substance at the wavelength of the measurement light, and the measurement object A position measuring method characterized in that a relationship defined by the following equations (1) and (2) is established between the refractive index nr at the wavelength of the measurement light of the uppermost layer.
sinθ> nr / na (1)
nr <na (2) The substance, diiodomethane _{(Diiodomethane: CH 2 I 2)} , 1- bromo-naphthalene _{(1-Bromo Napthalene: C 10} H 7 Br) or according to claim 5 or 6, characterized in that a mixture of these Position measurement method.   The position measuring method according to claim 5, wherein the uppermost layer of the object to be measured includes a photoresist.   The position of the surface of the measurement object is measured by the position measurement method according to any one of claims 5 to 8 in a state where the measurement object is placed on the stage of the exposure apparatus, and based on the result. A projection exposure method, wherein exposure is performed by adjusting optical conditions.   The projection exposure method according to claim 9, wherein the exposure is performed with the surface of the object to be measured covered with the substance. The projection exposure method according to claim 9, wherein the exposure is performed in a state where the substance is removed from a surface of the object to be measured.

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