JPH10233356A - Aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the manufacture of a defective LSI by coating part of heat sources which generate heat in an aligner which transfers a pattern on a mask onto a substrate by exposure with heat insulating paint. SOLUTION: The position of a wafer stage 8 which is moved by means of a wafer stage actuator 8a to a projection optical system 6 in the direction of the optical axis of the system 6 is measured at the time of exposure by means of auto-focus sensors 16a and 16b synchronously to a reticle stage 3 which is moved by means of a reticle actuator 3a. On the other hand, the deflection of the exposed surface of a wafer W from a surface perpendicular to the optical axis is measured by means of leveling sensors 17a and 17b. The position of the stage 8 and deflection of the wafer W are respectively corrected by means of their driving devices. Since the reticle R and wafer W which absorb heat, actuators 3a and 8a, light sources 5, 10, 16b, and 17b, and detectors 15, 16a, and 17a become heat generating heat sources, they are coated with heat insulating paint except optical paths.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mask pattern formed on a photosensitive substrate in a photolithography process in a manufacturing process of, for example, a semiconductor device, an image pickup device (such as a CCD), a liquid crystal display device, or a thin film magnetic head. The present invention relates to an exposure apparatus that performs exposure.

[0002]

2. Description of the Related Art For example, in a photolithography process (a process of forming a resist image of a mask pattern on a substrate) for manufacturing a semiconductor device or the like, a reticle pattern as a mask is exposed to a photoresist through a projection optical system. A projection exposure apparatus (stepper or the like) that exposes light onto a substrate (or a wafer or the like) coated with is used.

In a general projection exposure apparatus, a pattern drawn on a reticle is 1/5 to 1 by a projection optical system.
, And is exposed and transferred onto a substrate. that time,
The stage on which the reticle and the substrate are mounted is precisely positioned by a laser interferometer in a direction perpendicular to the optical axis, and the height is also determined in the direction of the optical axis using an AF sensor.

Further, the amount of deviation from the surface perpendicular to the optical axis on the surface of the substrate is detected by a leveling sensor to correct the inclination of the substrate. Further, the relative position between the substrate and the reticle is precisely positioned by the alignment sensor.

The reason why the position and orientation of the reticle and the substrate are accurately measured by using various sensors in the projection exposure apparatus is that the drawing pattern of the reticle to be exposed and transferred to the substrate is extremely fine. That is, in recent years, the integration degree of ULSI has been further increased, and it is required to form a pattern having a line width of, for example, 0.35 μm or less on a wafer.

Therefore, in order to perform the positioning of the reticle and the substrate with extremely high precision, the requirements for the positioning accuracy of the substrate stage and the reticle stage have become extremely strict.
Further, in order to obtain a high resolution, the numerical aperture of the projection optical system increases, the depth of focus becomes shallow, and the demands on the accuracy of AF and leveling are becoming more severe. Similarly, the allowable range of the alignment error with respect to the relative position between the reticle and the wafer is extremely limited.

On the other hand, there are obstacles described below when precisely positioning the reticle and the substrate. The exposure apparatus is generally hermetically sealed in a chamber in order to strictly control the temperature. However, there are many heat sources in the chamber, such as a stage driving unit, a reticle or wafer absorbing the exposure light, and a wall of the chamber that exchanges heat with the outside.

[0008] Due to such a heat source, the air in the chamber does not become spatially uniform and fluctuates over time. This causes a temporal fluctuation of the refractive index of air and a spatial gradient.

Here, not only the laser interferometer described above, but also an AF sensor, a leveling sensor, and an alignment sensor usually use a sensor using light.
When such measurement light passes through a space in which the refractive index of air fluctuates, the position measurement accuracy of a reticle or a wafer decreases. Further, when the exposure light passes through the space, there is a possibility that the image formation state may be adversely affected.

Further, the heat received from the above-mentioned heat source may cause thermal expansion of the mirror of the position measuring device and the reference index used for positioning, thereby causing thermal deformation. Even if such thermal deformation is extremely small, the measured values of the AF and leveling sensors change irrespective of the imaging state of the lens, and the relative relationship between the value of the laser interferometer of the stage and the actual stage position. Or the alignment measurement result may change irrespective of the relative position between the reticle and the substrate.

On the other hand, in the exposure operation and the alignment operation, the wafer stage moves in the case of the batch exposure type exposure apparatus, and in the case of the scanning (scanning) type exposure apparatus,
Since the wafer stage and reticle stage move,
The spatial gradient of the refractive index of air causes errors in the laser interferometer, the AF sensor, the leveling sensor, and the alignment sensor. Due to such poor positioning and deterioration of the imaging state, there is a possibility that a defective LSI will be produced.

In addition, a projection optical system for projecting a fine pattern on a reticle onto a wafer is extremely sensitive to temperature changes, and even a slight temperature difference affects optical characteristics such as focal length and aberration. The lower the allowable amount of temperature change. Therefore, the projection optical system is usually liquid-cooled by a separate device, and temperature control is strictly performed. However, when heat from the above-described heat source reaches the liquid-cooled projection optical system, the controlled temperature balance is lost, and the optical characteristics of the projection optical system change, which may cause a defective LSI.

Further, in a reduction projection exposure apparatus currently in practical use, an i-line or a KrF excimer laser is mainly used.
It is contemplated that an F excimer laser will be used. In setting a projection optical system using this light source, glass materials that can be used at present are limited, and i-line, Kr
There is a concern that only those having a larger thermal expansion coefficient than the glass material used for the F excimer light can be used. Therefore, in the conventional temperature adjustment method, there is a great possibility that the imaging state variation accompanying the temperature variation of the projection optical system exceeds the allowable amount in ULSI manufacturing.

In the manufacture of ULSIs with higher densities, if exposure is performed with the above-described reduction in positioning accuracy due to temperature fluctuations and instability of the projection optical system, there is a strong possibility that defective LSIs will be manufactured.

On the other hand, in order to reduce the temperature unevenness in the chamber as much as possible, an air conditioner is usually provided in the exposure apparatus in order to keep the temperature in the chamber constant. Such an air conditioner is, for example,
Clean air that is precisely maintained is introduced into the inside from the side of the chamber. The introduced air is exhausted to the outside via an exhaust duct provided at a lower portion (below the wafer stage) on the opposite side of the chamber.

However, such an air conditioner does not provide a fundamental solution as a measure against the heat source inside the chamber.

The present invention has been made to solve these problems, and has a contact portion with the outside of the chamber or
Apply thermal insulation coating to areas that are particularly sensitive to temperature changes, such as projection lenses, to isolate them from other heat sources, or, conversely, to isolate heat sources inside the chamber, It is an object of the present invention to provide an exposure apparatus that can prevent defective LSIs from being produced by applying heat insulating coating to a heat source so as not to exchange heat with other parts.

[0018]

In order to achieve the above object,
An exposure apparatus according to the present invention for exposing and transferring a pattern on a mask (R) onto a substrate (W) is provided by a heat source (3a, 8a, 5, 10, 16) for generating heat inside the exposure apparatus.
a, 16b, 17a, 17b, W, R) and the components (4a,
4b, 9a, 9b, 13, 15), and the heat sources (3a, 8a, 5, 10, 16a, 16b, 17a, 1)
7b, W, R) is characterized in that at least a part thereof is coated with a heat insulating paint.

According to the present invention, the heat sources (3a, 8)
a, 5, 10, 16a, 16b, 17a, 17b, W,
R) because at least a part of the heat source (3) is covered with the heat insulating paint, the heat source (3a, 8a, 5, 10, 16a, 16)
b, 17a, 17b, W, R) is used for components (4a, 4b, 9a, 9) for which the temperature stability of the exposure apparatus is required.
b, 13, 15) to prevent such portions from being heated and thermally deformed. In addition, such heat sources (3a, 8a, 5, 10, 16a, 16b, 17)
a, 17b, W, R), it is possible to prevent air fluctuations from occurring, and to prevent the optical paths (18, 19, 20, 21, 22) of the various sensors and the optical paths of the exposure light. Can be suppressed, and air fluctuations in the measured values can be prevented.

In order to achieve the above object, according to the present invention,
An exposure apparatus that exposes and transfers a pattern on a mask (R) onto a substrate (W) includes a heat source (3a, 8a, 5, 10, 16, 16a, 16b, 17a, 1a) that generates heat inside the exposure apparatus.
7b, W, R) and the components (4a, 4b, 9a, 9b, 1b,
3, 15), and the components (4a, 4b, 9)
a, 9b, 13, 15) are characterized in that at least a part thereof is covered with a heat insulating paint.

According to the present invention, since at least a part of the component is covered with the heat insulating paint, the heat source (3a, 8a, 5, 10, 16a, 16b, 17a, 17a, 1
7b, W, R).
a, 4b, 9a, 9b, 13, 15) can be prevented from being transmitted to the components, thereby preventing the components from being thermally deformed.

In order to achieve the above object, according to the present invention,
An exposure apparatus that exposes and transfers a pattern on a mask onto a substrate includes a chamber (100) that seals the exposure apparatus body from an external environment, and a heat exchange section (100a) that performs heat exchange between the inside and the outside of the chamber. , 11a), the chamber (100) and the heat exchanging section (100a, 11a).
a) at least a part of the film is coated with a heat insulating paint.

According to the present invention, the chamber (10
0) and at least a part of the heat exchange section (100a, 11a) is covered with a heat insulating paint, so that the inflow and outflow of heat from the chamber (100) and the heat exchange section (100a, 11a) are prevented. Accordingly, temperature fluctuations in the chamber can be suppressed, and thermal deformation of each element of the exposure apparatus and air fluctuations in the optical path of various sensors and exposure light can be prevented.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. The projection exposure apparatus shown in FIG. 1 is an example of a scanning projection exposure apparatus that exposes a reticle R and a photosensitive substrate W while scanning them synchronously with respect to an illumination area on the reticle R. As shown in FIG. 1, the projection exposure apparatus is generally installed in a constant temperature chamber 100. In the constant temperature chamber 100, temperature control with higher accuracy than in a normal clean room is performed. For example, while the temperature control in the clean room is controlled at about ± 1 ° C., the temperature control in the constant temperature chamber is ± 0.
It is kept within 1 ° C.

In the illustrated projection exposure apparatus, an intake duct 11 and an exhaust duct 12 are installed in a chamber 100 for temperature control. A temperature-controlled airflow moves across the element. Foreign matter (dust) floating in the clean room is placed in the chamber 100, especially in the exposure apparatus main body including the projection optical system 6.
A HEPA (or ULPA) filter and a chemical filter are arranged near the air intake port (not shown) of the chamber 100 or the intake duct 11 to prevent the inflow of sulfate ions, ammonium ions, and the like. The intake duct 11 is connected to an external air supply device (not shown) via the intake pipe 11.

The scanning projection exposure apparatus shown in FIG. 1 includes a light source (not shown) and an illumination optical system 1, a reticle stage 3 for moving a reticle R in a scanning direction, a projection optical system 6, a wafer stage 8 for moving a wafer W, It mainly comprises an alignment system (15; 16a, 16b; 17a, 17b) for wafer alignment. As a light source, an emission line (g line, i line) in the ultraviolet region of a mercury lamp, excimer laser light such as KrF, ArF, or the like is generally used. Also, the illumination optical system 1
Consists of fly-eye lens, condenser lens, etc.
Finally, the reticle R is illuminated via a condenser lens (not shown). The illumination optical system 1 is a reticle R which is a mask on which a circuit pattern or the like is drawn with illumination light from a light source.
Is illuminated with a substantially uniform illuminance and a predetermined solid angle. A light source (not shown) is generally disposed outside the chamber 100 and is led to the illumination optical system 1 using a mirror (not shown).

The reticle stage 3 is set on the optical axis AX of the projection optical system 6 and between the projection optical system 6 and the illumination optical system 1, and is controlled by a reticle actuator 3a in a predetermined direction in the scanning direction (Y direction). It can be moved at a scanning speed. The reticle stage 3 is moved by a stroke such that the entire pattern area of the reticle R crosses at least the optical axis AX of the projection optical system. A reticle stage 3 has a movable mirror 4 that reflects a laser beam from an interferometer 5 at an end in the X and Y directions.
Is fixed, and the XY position of the reticle stage 3 is measured by the interferometer 5, for example, in units of 0.6 nm. The measurement result by the interferometer 5 is sent to a stage control system (not shown), and the reticle stage 3 is always positioned with high accuracy.

On reticle stage 3, a reticle holder (not shown) is installed, and reticle R is installed on the reticle holder. The reticle R is similarly held by suction on a reticle holder by a vacuum chuck (not shown).
Above the reticle stage 3, a reticle alignment microscope 2 facing the optical axis AX is mounted. By observing the relative positions of the reference marks (not shown) formed on the reticle R and the reference marks 13 on the wafer stage 8 by using the two sets of microscopes 2, the relationship between the reticle R and the wafer stage is determined. It is accurately measured and positioned.

The reticle R is placed on the reticle stage 3
Illumination is performed in a rectangular (slit-shaped) illumination area whose length is in a direction (X direction) perpendicular to the scanning direction (Y direction) of the reticle R. This illumination area is defined by a field stop (not shown) disposed above the reticle stage and at or near a plane conjugate with the reticle R.

The illumination light that has passed through the reticle R enters the projection optical system 6, and a circuit pattern image of the reticle R is formed on the wafer W by the projection optical system 6. The projection optical system 6 includes
A plurality of lens elements (not shown) are accommodated such that the optical axis AX is a common optical axis.

The projection magnification of the pattern image of the reticle R projected on the wafer W is determined by the magnification and arrangement of the lens elements. A reticle pattern in a slit-shaped illumination area (center substantially coincides with optical axis AX) on reticle R is projected onto wafer W via projection optical system 6. Since the wafer W has an inverted image relationship with the reticle R via the projection optical system 6, the reticle R is exposed in the −Y direction (or +
When the wafer W is scanned in the Y direction) at the speed Vr, the wafer W is moved at the speed Vr.
Scanning is performed at the speed Vw in synchronization with the reticle R in the + Y direction (or -Y direction) opposite to the direction of r, and the entire surface of the shot area on the wafer W is sequentially exposed with the pattern of the reticle R. The scanning speed ratio (Vr / Vw) is determined by the reduction magnification of the projection optical system 6.

The wafer W is vacuum-sucked on a wafer holder (not shown) held on the wafer stage 8. The wafer stage 8 is moved not only in the scanning direction (Y direction) but also in a direction perpendicular to the scanning direction (X direction) so that a plurality of shot areas on the wafer W can be scanned and exposed.
The operation of scanning each shot area on the wafer W and the operation of moving to the exposure start position of the next shot area are repeated.

The wafer stage 8 is driven by a wafer stage actuator 8a such as a motor. The moving speed of the wafer stage 8 is adjusted according to the ratio Vr / Vw, and moves in synchronization with the reticle stage 3. A movable mirror 9a is fixed to an end of the wafer stage 8, while a movable mirror 9b is fixed to a fixed portion (for example, the projection optical system 6) of the exposure apparatus, and a laser beam from the interferometer 10 is transmitted to the movable mirror 9a.
The coordinate position of the wafer stage 8 in the XY plane is constantly monitored by detecting the phase difference with the interferometer 10. Light reflected from the movable mirrors 9a and 9b is detected by the interferometer 10 with a resolution of, for example, about 0.6 nm. The reticle actuator 3a
The wafer actuator 8a is constituted by a normal motor.

The projection exposure apparatus has a function of accurately exposing a new pattern to a pattern already formed on the wafer W by exposure. In order to perform this function, the projection exposure apparatus has a function (wafer alignment system) for detecting the position of the alignment mark on the wafer W and determining the position for performing the overlay exposure. In this example, the projection optical system 6 is used as the wafer alignment system.
An optical alignment system (15) is provided separately from the optical alignment system. A laser, a halogen lamp, or the like is used as a light source of the wafer alignment system. Note that a reference index 13 serving as a reference for the alignment sensor is arranged on the wafer stage 8, and the reference index 13 is detected by the alignment sensor 15.

At the time of exposure, the wafer stage 8
The position in the optical axis direction with respect to the projection optical system 6 is measured by AF (auto focus) sensors 16a and 16b. On the other hand, the deviation of the exposure surface of the wafer W from the plane perpendicular to the optical axis is determined by the leveling sensor 17a and the leveling sensor 17a. 17b, and each is corrected by a driving device (not shown).
Various sensors can be used for AF and leveling.

Exposure is performed after or after the completion of the positioning. In the case of a scan type exposure apparatus, the reticle R and the wafer W
Are moved synchronously while maintaining the imaging relationship.

Here, the reticle R and the wafer W that have absorbed the exposure light, the actuators 3a and 8a, the light sources 5, 10, and 1
6b, 17b and the detectors 15, 16a, 17a can be heat sources that generate heat. Therefore, in the present embodiment, such a heat source is subjected to heat-insulating coating except for the optical path, so that heat radiation can be prevented as much as possible. Fluctuation can be prevented.

On the other hand, in the present embodiment, the mirrors 4, 9a, 9b, the reference index 13 or the alignment sensor 15, which are required to have temperature stability, which cause errors in optical measurement values due to thermal deformation, A heat insulating coating is applied to portions that support them other than the reflection surface or the index surface (the alignment sensor 15 is the entire unit), thereby preventing thermal deformation as much as possible. If thermal deformation of the mirrors 4, 9a, 9b, the reference index 13, and the alignment sensor 15 is prevented, optical measurement values obtained via such mirrors and the like are stabilized, and thereby accurate alignment is achieved.

Further, a liquid cooling device (not shown) is provided in the projection optical system 6, and the temperature is controlled separately.
When heat is transmitted from a heat source other than the projection optical system 6, the managed temperature changes, and optical characteristics such as aberration and focal length may fluctuate. Therefore, in the present embodiment, heat insulation coating is applied to the outer periphery of the projection optical system 6 to prevent transmission of radiant heat and stabilize optical characteristics.

As the heat insulating coating material, for example, a styrofoam-containing paint (or a foamable paint) can be used.

On the other hand, in the present embodiment, the entire surface of the outer wall 100a of the chamber 100 and the entire circumference of the intake pipe 11a that can be a heat exchange part are also coated with heat insulation, so that the heat exchange part becomes a heat source. This prevents the occurrence of thermal deformation and air turbulence in each part where temperature stability is required.

That is, according to the present embodiment, by applying heat insulation coating to a heat source, an element requiring temperature stability or a heat exchange part, generation of air fluctuation is prevented, and thermal deformation of the element is prevented. This makes it possible to achieve more precise alignment and exposure, thereby enabling exposure transfer of a finer pattern to a wafer.

Note that, in addition to those shown in the present embodiment, a portion where temperature stability is required more than in the chamber,
Alternatively, it is effective in ULSI manufacturing to apply heat-insulating coating to a portion near the heat generating portion to eliminate the influence of heat as much as possible. Applying heat insulating coating to a heat source and a heat exchange unit other than those described above is also effective in ULSI production. Furthermore, although the present embodiment has been described with respect to a scanning type exposure apparatus, it is needless to say that the present invention can be applied to other exposure apparatuses such as a batch exposure type.

FIG. 2 is a schematic view of an exposure apparatus according to a second embodiment of the present invention. FIG. 1 shows a second embodiment.
Is different from the first embodiment in that the reticle actuator 3a and the wafer actuator 8a are constituted by linear motors instead of ordinary motors. Since other embodiments are the same in both embodiments, detailed description thereof will be omitted.

[0045]

As described above, according to the exposure apparatus of the present invention, since at least a part of the heat source is covered with the heat insulating paint, the radiation of heat from the heat source is prevented, and the heat is exposed. The heat is transmitted to the components requiring temperature stability of the device, and it is possible to prevent such portions from being heated and thermally deformed. Further, by preventing the radiation of heat from such a heat source, it is possible to prevent the fluctuation of air from occurring.

Further, according to the exposure apparatus of the present invention, since at least a part of the component requiring temperature stability is covered with the heat insulating paint, the heat radiated from the heat source is applied to the component. It can be prevented from being transmitted, thereby preventing the components from being thermally deformed.

According to the exposure apparatus of the present invention, since at least a part of the chamber and the heat exchange section are covered with the heat insulating paint, the radiation of heat from the chamber and the heat exchange section can be prevented. It is transmitted to each element of the exposure apparatus, and it is possible to prevent the element from being heated and causing air fluctuation or thermal deformation.

[Brief description of the drawings]

FIG. 1 is a schematic view of an exposure apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic view of an exposure apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 illumination system 2 reticle alignment microscope 3 reticle stage 3a reticle stage actuator (motor) 4a reticle stage moving mirror 4b reticle stage fixing mirror 8 wafer stage 8a wafer stage actuator (motor) 9a wafer stage moving mirror 9b wafer stage fixing mirror 11 Intake duct 12 Exhaust duct 13 Reference index 15 Wafer alignment optical system 16a, 16b AF (autofocus) sensor 17a, 17b Leveling sensor 18 Wafer stage interferometer optical path 19 Reticle stage interferometer optical path 20 AF sensor optical path 21 Leveling sensor optical path 22 Alignment sensor Optical path R Reticle W Wafer

Claims (3)

[Claims] 1. An exposure apparatus for exposing and transferring a pattern on a mask onto a substrate, comprising: a heat source that generates heat inside the exposure apparatus; and a component that requires temperature stability inside the exposure apparatus. An exposure apparatus, wherein at least a part of the heat source is covered with a heat insulating paint. 2. An exposure apparatus for exposing and transferring a pattern on a mask onto a substrate, comprising: a heat source that generates heat inside the exposure apparatus; and a component that requires temperature stability inside the exposure apparatus. An exposure apparatus, wherein at least a part of the constituent elements is covered with a heat insulating paint. 3. An exposure apparatus for exposing and transferring a pattern on a mask onto a substrate, comprising: a chamber for sealing an exposure apparatus main body from an external environment; and a heat exchange section for exchanging heat between the inside and the outside of the chamber. An exposure apparatus, wherein at least a part of the chamber and the heat exchange unit are covered with a heat insulating paint.