JP2010245144A - Aligner and method of manufacturing device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aligner that minimizes an error depending upon the shape of a scale when a substrate stage is positioned using a position measuring device such as an encoder. <P>SOLUTION: The aligner 50 includes the substrate stage 6 for holding a substrate 5, an optical measurement unit 7 which measures the position of the substrate stage 6, and the scale 8 as a target of reflection for measurement light from the optical measurement unit 7, and further includes a supply system which supplies temperature control air for controlling the temperature in the space where the substrate stage 6 is installed and an exhaust system which exhausts it, and the supply system includes a first supply system 11 which supplies the temperature control air to a periphery of a scanning part of the substrate stage, an exhaust system 14, a second supply system 13 which supplies the temperature control air to a periphery of an installation part of the scale 8, and an exhaust system 15. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exposure apparatus and a device manufacturing method using the same.

  In a lithography process, which is a manufacturing process for semiconductor elements, liquid crystal display elements, and the like, an exposure apparatus applies a pattern of an original (reticle) to a substrate to be processed (for example, a resist layer on the surface via a projection optical system). A wafer or a glass plate). As this exposure apparatus, a step-and-repeat projection exposure apparatus (stepper) and a step-and-scan projection exposure apparatus (scan) are frequently used.

  In recent years, along with the miniaturization of a pattern to be transferred to a wafer, an exposure apparatus is required to further improve the alignment accuracy in addition to improving the positioning accuracy of the wafer or reticle. On the other hand, one of the factors that affect the alignment optical system is a portion that houses the optical system, a portion that holds the optical system, or a temperature change in the optical path of the optical system. As a countermeasure for suppressing the influence due to the temperature change, for example, Patent Document 1 discloses an exposure apparatus in which the exposure apparatus is accommodated in a temperature-controlled chamber and the optical performance is stably maintained without increasing the size of the air conditioning system. ing.

  In such an exposure apparatus, a positioning accuracy of 1 nm or less is also required for a reticle stage for placing a reticle and a substrate stage for placing a wafer and scanning the projection optical system. Therefore, an interferometer system employing a laser interferometer, an encoder, or the like is used for the position measurement. For example, Patent Document 2 discloses a lithographic projection apparatus that performs stage position measurement with an encoder that can always measure at a short distance. As for the configuration of the interferometer system, there is one that can measure a two-degree-of-freedom planar direction of a measurement target with one sensor head. Further, for example, Patent Document 3 discloses an interferometer capable of measuring two degrees of freedom in a direction parallel to and perpendicular to the scale, and Patent Document 4 discloses a detection apparatus capable of measuring at least three degrees of freedom. ing.

JP 2000-277416 A JP 2002-151405 A JP 2007-171206 A JP 2006-10645 A

  However, when the interferometer system is used in the atmosphere, an error occurs in the interferometer optical path due to air fluctuations. In particular, for encoders, the existence of a scale to be measured is indispensable, but with encoders and other optical measurement means that can measure the direction perpendicular to the scale, shape errors such as thermal deformation of the scale are measured. There is a problem that it leads to an error. On the other hand, Patent Documents 1 to 4 do not disclose a method for dealing with this problem.

  The present invention has been made in view of such a situation, and an exposure apparatus that minimizes an error depending on the shape of a scale when positioning a substrate stage using a position measurement device such as an encoder is provided. provide.

  In order to solve the above problems, an exposure apparatus comprising a substrate stage that holds a substrate, an optical measurement unit that measures the position of the substrate stage, and a scale that is a reflection target of measurement light from the optical measurement unit. And a supply system that supplies temperature-controlled air for adjusting the temperature in the space in which the substrate stage is installed. The supply system supplies the temperature-controlled air around the scanning unit of the substrate stage. And a second supply system for supplying temperature-controlled air around the scale installation section.

  According to the present invention, the temperature control air supply system for controlling the temperature in the space in which the substrate stage is installed is made of two types of systems, so that the thermal deformation of the scale is minimized during the exposure process and maintenance. The positioning accuracy of the substrate stage can be improved.

1 is a schematic diagram showing a configuration of an exposure apparatus according to a first embodiment of the present invention. It is the schematic which shows the structure of the exposure apparatus which concerns on the 2nd Embodiment of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic view showing the arrangement of an exposure apparatus according to the first embodiment of the present invention. The exposure apparatus 50 includes an illumination optical system 1, a reticle stage 3 that holds a reticle (original) 2, a projection optical system 4, and a substrate stage 6 that holds a wafer (substrate) 5. The exposure apparatus 50 in this embodiment is a scanning projection exposure apparatus that employs a step-and-repeat method or a step-and-scan method and exposes a circuit pattern formed on the reticle 2 onto the wafer 5. . In the following figure, the Z axis is taken in parallel to the optical axis of the projection optical system, the Y axis is taken in the scanning direction of the reticle and wafer during scanning exposure in a plane perpendicular to the Z axis, The description will be made by taking the X axis in the orthogonal non-scanning direction.

  The illumination optical system 1 includes a light source unit (not shown) and illuminates a reticle 2 on which a transfer circuit pattern is formed. In the light source unit, for example, a laser is used as the light source. Usable lasers include an ArF excimer laser having a wavelength of about 193 nm, a KrF excimer laser having a wavelength of about 248 nm, and an F2 excimer laser having a wavelength of about 157 nm. The type of laser is not limited to the excimer laser, and for example, a YAG laser may be used, and the number of lasers is not limited. When a laser is used for the light source unit, it is preferable to use a light beam shaping optical system that shapes a parallel light beam from the laser light source into a desired beam shape and an incoherent optical system that makes a coherent laser incoherent. Furthermore, the light source that can be used for the light source unit is not limited to the laser, and one or a plurality of lamps such as a mercury lamp and a xenon lamp can be used.

  The illumination optical system 1 includes a lens, a mirror, a light integrator, a diaphragm, and the like. In general, an optical system is arranged in the order of a condenser lens, a fly-eye lens, an aperture stop, a condenser lens, a slit, and an imaging optical system. The illumination optical system 1 can be used regardless of on-axis light or off-axis light. The light integrator includes an integrator configured by stacking a fly-eye lens and two sets of cylindrical lens array plates. The light integrator may be replaced with an optical rod or a diffraction element. The aperture stop is configured as a circular stop, an annular illumination stop for modified illumination, a quadrupole illumination stop, or the like.

  The reticle 2 is, for example, a quartz glass original plate on which a circuit pattern to be transferred is formed. The reticle stage 3 is a stage that can move in a fixed direction (XY direction), and is a device that mounts and holds the reticle 2.

  The projection optical system 4 projects and exposes the pattern on the reticle 2 illuminated with the exposure light from the illumination optical system 1 onto the wafer 5 at a predetermined magnification (for example, 1/4 or 1/5). As the projection optical system 4, an optical system composed only of a plurality of optical elements or an optical system composed of a plurality of optical elements and at least one concave mirror (catadioptric optical system) can be employed. Alternatively, as the projection optical system 4, an optical system composed of a plurality of optical elements and at least one diffractive optical element such as a kinoform, an all-mirror optical system, or the like can be employed.

  The wafer 5 is an object to be processed made of silicon having a resist (photosensitive agent) applied on the surface thereof. The substrate stage 6 is a stage that can move in a certain direction (XYZ direction), and is a device for mounting and holding the wafer 5.

  In the exposure apparatus 50 of this embodiment, the diffracted light emitted from the reticle 2 passes through the projection optical system 4 and is projected onto the wafer 5. The reticle 2 and the wafer 5 are in a conjugate relationship. In the case of a scanning projection exposure apparatus, the pattern of the reticle 2 is transferred onto the wafer 5 by scanning the reticle 2 and the wafer 5. In the case of a stepper (step-and-repeat type exposure apparatus), exposure is performed with the reticle 2 and the wafer 5 being stationary.

  Next, the peripheral configuration of the substrate stage 6 that is a feature of the present invention will be described. First, the exposure apparatus 50 has a position measurement device for positioning the wafer 5 so as to always be in a predetermined position before the exposure process is performed around the substrate stage 6. The position measurement device is an optical measurement unit 7 installed at a plurality of positions (for example, three locations) on the upper side surface of the substrate stage 6 and is a reflection target of measurement light projected from the optical measurement unit 7. And a scale 8 suspended in the XY plane.

  The optical measurement unit 7 projects the measurement light onto the scale 8 installed on the surface plate 9 within the XY plane orthogonal to the optical axis of the projection optical system 4, and subsequently the measurement light reflected from the scale 8. Light is received and a measurement signal is output to a position detection circuit (not shown). The position detection circuit detects the relative position of the wafer 5 based on the measurement signal, and transmits the detection result to a control system (not shown) of the substrate stage 6. The control system controls the positioning of the substrate stage 6 based on the detection result. The optical measurement unit 7 has a configuration capable of measuring in three directions of XYZ.

  The scale 8 has a liquid cooling pipe 8a penetrating inside or attached to a side surface. The liquid circulating in the liquid cooling pipe 8a is maintained at a constant temperature by a temperature adjusting unit (not shown) and a temperature control unit, or the temperature is controlled so that the temperature of the scale 8 is constant, Minimizes thermal deformation.

  Although not shown, the exposure apparatus 50 includes a temperature-controlled chamber that accommodates the main components. In general, the temperature in the chamber is controlled with higher accuracy than in a clean room in which the exposure apparatus 50 is installed. For example, the temperature of the clean room is controlled in a range of ± 2 to 3 ° C., while the temperature in the chamber is maintained in a range of ± 0.1 ° C. In particular, in the substrate stage space where the optical measurement unit 7 that requires precise measurement is installed, the temperature of the substrate stage space is supplied by supplying temperature-controlled air adjusted to a desired temperature from an air supply unit (not shown). Is ideally maintained at 23 ± 0.01 ° C.

  In contrast, according to the present invention, temperature-controlled air supplied to the substrate stage space in order to adjust the internal temperature is supplied from two types of supply systems, the first supply system and the second supply system. It is characterized by that. The first supply system includes a supply pipe 10 extending from the air supply unit, and a blow-out unit 11 for efficiently injecting the temperature-controlled air supplied from the supply pipe 10. The first supply system emits temperature-controlled air toward the entire substrate stage 6, and is a supply system mainly responsible for temperature adjustment around the scanning unit of the substrate stage 6. In this case, the wind speed of the temperature control air from the blowing part 11 shall be about 0.5 m / s. On the other hand, the second supply system includes a supply pipe 12 extending from the air supply section, and a blowout section 13 for efficiently injecting the temperature-controlled air supplied from the supply pipe 12. The second supply system is a supply system that injects temperature-controlled air toward the entire position measuring device, and is mainly responsible for temperature adjustment around the installation portion of the scale 8. In this case, the wind speed of the temperature-controlled air from the blowing part 13 is about 3 m / s.

  Further, exhaust portions 14 and 15 corresponding to the respective blowout portions are installed on the side surface of the chamber facing the blowout portion 11 and the blowout portion 13. The exhaust units 14 and 15 collect the temperature-controlled air after supply, create an efficient air flow, and prevent air stagnation from occurring in the substrate stage space. The exhaust parts 14 and 15 are connected to exhaust pipes 16 and 17 of different systems, respectively.

  Next, operations and effects of the two types of air supply systems will be described. In the present invention, first, temperature-controlled air is supplied from the first supply system and the second supply system, so that the temperature of the entire substrate stage space is controlled to be substantially the same as the temperature of the temperature-controlled air. Thereby, the measurement error by the temperature fluctuation (refractive index fluctuation | variation) of the air on the optical path of the measurement light irradiated from the optical measurement part 7 resulting from a temperature gradient can be suppressed. In particular, near the position measuring device, temperature-controlled air having a speed higher than that of the temperature-controlled air supplied from the first supply system is supplied from the second supply system. It is possible to cool, and the temperature fluctuation of the air can be further suppressed.

  Further, when work is performed in the substrate stage space such as maintenance of the substrate stage 6, only the second supply system is supplied / exhausted, the first supply system is stopped, and the blowing unit 11 and the exhaust unit 14 are moved. Thus, the work can be performed while maintaining the temperature control of the scale 8. As a result, the temperature deformation of the scale 8 can be minimized, and the recovery time to a predetermined exposure accuracy after the work can be shortened.

  Further, in addition to the above-described piping configuration, the supply pipe 10 connected to the blowing part 11 and the exhaust pipe 16 connected to the exhaust part 14 are connected by a bypass pipe 18. Further, the supply pipe 10 and the exhaust pipe 16 are each provided with an adjustment valve 19, and the bypass pipe 18 is provided with an adjustment valve 20. The bypass pipe 18 mainly plays a role of releasing excess temperature-controlled air from the air supply unit in order to appropriately secure the flow rate of temperature-controlled air supplied from the first supply system. Further, as described above, when the work is performed in the substrate stage space, the supply and exhaust of the first supply system can be stopped by closing the adjustment valve 19 and opening the adjustment valve 20.

  In general, in the substrate stage space, air is circulated, and chemical substances are removed by a chemical filter (not shown) or minute substances are removed by a ULPA filter (not shown). At this time, if the position of the exhaust unit 14 is moved, the exhaust unit 14 sucks air in the clean room, and the lifetimes of the chemical filter and the ULPA filter are shortened. On the other hand, in the present invention, the temperature control air can be bypassed from the supply pipe 10 to the exhaust pipe 16 via the bypass pipe 18 so that the operation can be performed while circulating the temperature control air. , And the lifetime of the ULPA filter can be extended.

  As described above, in the present invention, the temperature-controlled air supplied to the substrate stage space is supplied from the two types of supply systems, the first supply system and the second supply system. As a result, the temperature around the position measuring device can be efficiently adjusted, and measurement errors caused by shape errors such as thermal deformation of the scale 8 can be minimized. For example, according to the present invention, the positioning accuracy of the substrate stage 6 can be 1 nm or less. Furthermore, since the maintenance work of the substrate stage space can be performed efficiently, it is possible to shorten the recovery time to a predetermined exposure accuracy after the maintenance work is completed.

(Second Embodiment)
Next, an exposure apparatus according to the second embodiment of the present invention will be described. FIG. 2 is a schematic view showing the arrangement of an exposure apparatus according to the second embodiment of the present invention. In FIG. 2, the same components as those in FIG. The exposure apparatus 60 of the present embodiment is characterized in that a partition member 21 that divides the substrate stage space is provided between the first supply system and the second supply system.

  The partition member 21 is a plate material or a film used when work such as maintenance of the substrate stage 6 is performed. The partition member 21 divides the substrate stage space into a first circulating space 22 for temperature-controlled air around the scanning unit of the substrate stage 6 and a second circulating space 23 for temperature-controlled air around the scale 8. , Arranged in the XY plane. The partition member 21 may have a removable structure so as to be installed only during work. Or the partition member 21 is good also as a structure equipped so that it can accommodate between the blowing part 11 and the blowing part 13 at the time of an exposure process as a slide structure or the structure wound up in vinyl or resin sheet shape.

  Thereby, when working in the first circulation space 22, the temperature of the second circulation space 23 can be kept constant by the second supply system, so that the temperature deformation of the scale 8 is suppressed to a minimum. It is possible to shorten the recovery time to a predetermined exposure accuracy after the work is completed. Further, when working in the first circulation space 22, it is possible to prevent the scale 8 from being damaged by contact with the scale 8.

(Device manufacturing method)
Next, an embodiment of a device manufacturing method using the exposure apparatus will be described. A device such as a semiconductor element, a liquid crystal display element, an image pickup element (CCD, etc.), a thin film magnetic head, and the like, a step of exposing a resist-coated substrate using the exposure apparatus, and a step of developing the exposed substrate And other known processes. The known processes include at least one process such as oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, and packaging.

  The present invention is not limited to the above-described embodiment, and each configuration may be alternatively substituted as long as the object of the present invention is achieved. For example, in the above embodiment, the temperature control mechanism of the substrate stage space is described as being used alone. However, the temperature control mechanism that is normally used and the temperature control mechanism of the present invention may be used in combination. Good.

5 Substrate 6 Substrate Stage 7 Optical Measurement Unit 8 Scale 11 Blowout Unit 13 Blowout Unit 14 Exhaust Unit 15 Exhaust Unit 18 Bypass Pipe 21 Partition Member

Claims (9)

An exposure apparatus comprising a substrate stage that holds a substrate, an optical measurement unit that measures the position of the substrate stage, and a scale that is a reflection target of measurement light from the optical measurement unit,
A supply system for supplying temperature-controlled air for adjusting the temperature in the space in which the substrate stage is installed;
The supply system includes a first supply system that supplies the temperature-controlled air around the scanning unit of the substrate stage, and a second supply system that supplies the temperature-controlled air around the installation unit of the scale. An exposure apparatus characterized by the above.   Each of the first supply system and the second supply system includes a blow-out unit that injects the temperature-controlled air, and an exhaust unit that exhausts the temperature-controlled air supplied from the blow-out unit. The exposure apparatus according to claim 1.   3. The exposure apparatus according to claim 1, wherein wind speeds of the temperature-controlled air supplied from the first supply system and the second supply system are different from each other.   4. The exposure apparatus according to claim 3, wherein a wind speed of the temperature-controlled air supplied from the second supply system is faster than a wind speed of the temperature-controlled air supplied from the first supply system.   The partition member which divides | segments the inside of the space in which the said substrate stage was installed into the space of a said 1st supply system and a said 2nd supply system is provided. The exposure apparatus described in 1.   The exposure apparatus according to claim 5, wherein the partition member is removable.   The exposure apparatus according to claim 5, wherein the partition member is retractable. The first supply system has a bypass pipe connected to the blowing part and the exhaust part,
When working in the space where the substrate stage is installed, the first supply system bypasses the temperature control air from the bypass pipe, and the second supply system controls the temperature of the scale. The exposure apparatus according to claim 1, wherein the exposure apparatus is performed. A step of exposing the substrate using the exposure apparatus according to claim 1;
Developing the substrate;
A device manufacturing method characterized by comprising:

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