Abstract:
An exposure apparatus includes a light source, an illumination optical system for illuminating an original with light from the light source, and a projection optical system for projecting a pattern of the original, illuminated by the illumination optical system, onto a substrate. In addition, a radiation member is disposed opposite to a subject of temperature adjustment which corresponds to at least one of an optical element of the illumination optical system, an optical element of the projection optical system and the original, and a control system controls a temperature of the radiation member in accordance with a state or exposure of the subject of temperature adjustment.

Description:
FIELD OF THE INVENTION AND RELATED ART 
   This invention relates to an exposure apparatus and a device manufacturing method, usable in the manufacture of devices having a very fine pattern, such as LSIs, for example. 
   As a projection exposure apparatus for transferring a reticle pattern onto a silicon wafer in the manufacture of semiconductor devices, EUV exposure apparatuses using EUV light (extreme ultraviolet light) having a wavelength of about 13-14 nm as an exposure light source have been proposed, in which apparatus, a reticle pattern is projected and transferred by use of a mirror optical system and in a vacuum environment. 
   Referring now to  FIGS. 1 ,  11 A,  11 B,  12 A,  12 B,  13 A and  13 B, the structure of a conventional EUV exposure apparatus will be explained. In  FIG. 1 , denoted at  1  is an excitement laser in which laser light is projected toward a point where a light source material for producing a light emission point of a light source is gasified, liquefied or gasified by atomization, to cause plasma excitement of atoms of the light source material to thereby produce light emission. A YAG solid laser may be used, for example. 
   Denoted at  2  is a light source emission unit as an exposure light source, and it has a structure having a vacuum ambience maintained therein. Denoted at  2 A is a light emission point (hereinafter, “light source”) of the exposure light source. Denoted at  2 C is a light source mirror, which is provided as a semi-spherical surface mirror about the light source  2 A, for collectively reflecting total-spherical surface light rays from the light source  2 A while keeping them in the emission direction. Toward the point of the light source  2 A, as a light emission element, any one of liquefied Xe, atomized fog of liquefied Xe, or Xe gas is discharged through a nozzle (not shown). Also, light from the excitement laser  1  is projected thereto. 
   Denoted at  3  is a vacuum chamber for accommodating therein the whole structure of the exposure apparatus. The vacuum level inside the chamber can be maintained by means of a vacuum pump  4 . Denoted at  5  is an exposure light introducing unit for introducing exposure light from the light source light emission point  2  and also for shaping the same. It comprises mirrors  5 A- 5 D, and it functions to homogenize the exposure light and also to shape the same. 
   Denoted at  6  is a reticle stage, and an original  6 A, which is a reflective original of an exposure pattern, is mounted in a movable portion of the reticle stage. Denoted at  7  is a reduction projection mirror optical system for projecting, in a reduced scale, the exposure pattern reflected from the original  6 A. The exposure pattern reflected from the original  6 A is projected to and reflected by mirrors  7 A- 7 E sequentially, whereby it is reduced and projected on a wafer  8 A finally at a predetermined reduction magnification. Denoted at  8  is a wafer stage, which can be controllably positioned with respect to six axes of the X, Y and Z directions, tilt directions about the X and Y axes, a rotational direction about the Z axis, so as to position the wafer  8 A (Si substrate) to which the pattern reflectively projected from the original  6 A is to be transferred. 
   Denoted at  9  is a reticle stage support for supporting the reticle stage  6  with respect to the floor where the apparatus is mounted. Denoted at  10  is a projection system support for supporting the reduction projection mirror system  7  with respect to the floor. Denoted at  11  is a wafer stage support for supporting the wafer stage  8  with respect to the floor. Between the reticle stage  6  and the reduction projection mirror optical system  7  and between the reduction projection mirror system  7  and the wafer stage  8 , which are isolated and independently supported by means of the above-described reticle stage support  9 , the projection system support  10  and the wafer stage support  11 , there is provided means (not shown) having a function for measuring the relative position and for maintaining the components at a predetermined relative position. 
   The reticle stage support  9 , the projection system support  10  and the wafer stage support  11  are provided with a mount (not shown) for insulating them against vibration from the floor where the apparatus is mounted. 
   Denoted at  12  is a reticle stocker for temporarily storing therein reticles (originals  6 A) from the outside of the machine to the inside of the machine. A plurality of reticles, having different patterns and corresponding to different exposure conditions, are stored in a storing container. Denoted at  13  is a reticle changer for choosing a reticle to be used, out of the reticle stocker  12 , and for conveying the same. Denoted at  14  is a reticle alignment unit having a rotary hand, which is movable in X-, Y- and Z-axis directions and rotatable around the Z axis. The reticle alignment unit receives an original  6 A from the reticle changer  13 , and rotates it by 180 degrees. Then, the reticle alignment unit conveys the original  6 A toward a reticle alignment scope  15  portion, which is provided at an end portion of the reticle stage  6 , and then brings it into alignment with an alignment mark  15 A (see  FIG. 11 ) provided on a reference of the reduction projection mirror optical system  7 , by minutely moving the original  6 A in X-, Y- and Z-axis directions and in a rotational direction about the Z axis. After completion of the alignment, the original  6 A is chucked onto the reticle stage  6 . 
   Denoted at  16  is a wafer stocker for temporarily storing wafers  8 A from the outside of the machine to the inside of the machine. A plurality of wafers are stored in a storing container. Denoted at  17  is a wafer conveying robot that functions to choose a wafer  8 A to be processed, out of the wafer stocker  16 , and conveys the same to a wafer mechanical prealignment temperature adjuster  18 . The wafer mechanical prealignment temperature adjuster  18  has a function for performing feed coarse alignment of the wafer in the rotational direction and a function for simultaneously adjusting the wafer temperature in registration with an inside adjusted temperature of the exposure apparatus. Denoted at  19  is a wafer supply hand, and it functions to introduce and load the wafer  8 A, having been aligned and temperature adjusted at the wafer mechanical prealignment temperature adjuster  18 , onto the wafer stage  8 . 
   Denoted at  20  and  21  are gate valves, which function as a gate opening/closing mechanism, through which a reticle and a wafer can be inserted from outside the machine. Denoted at  22  is also a gate valve. Inside the apparatus, the exposure space and the space for the wafer stocker  16  and the wafer mechanical prealignment temperature adjuster  18  are isolated from each other by means of a partition wall, and the gate valve  22  is opened only when a wafer  8 A is loaded and unloaded. With this isolation using a partition, the volumetric capacity to be opened to the atmosphere as a wafer  8 A is loaded from and unloaded back to the outside of the machine can be minimized, so that a vacuum balanced state can be resumed quickly. 
   In  FIGS. 11A ,  11 B,  12 A and  12 B, denoted at  6 B is a reticle chuck slider, and denoted at  6 C is a reticle driving means. Denoted at  6 F is an electrostatic chuck electrode. Denoted at  14 A is a reticle alignment hand, and denoted at  14 B is a reticle alignment electrostatic chuck. Denoted at  37  is an original alignment control circuit. 
   In the exposure apparatus described above, the light source mirror  2 C for collecting exposure light from the light source light emitting unit  2  as the exposure operation starts from the non-exposure period, the mirrors  5 A- 5 D of the exposure light introducing unit for introducing and shaping the collected exposure light, and the mirrors  7 A- 7 E of the reduction projection mirror optical system for reducing and projecting an exposure pattern reflected from the original  6 A are all formed with a Mo—Si multilayered film, produced by vapor deposition or sputtering, so that the exposure light from the light source  2 A is assuredly reflected by the individual reflection surfaces. The reflectance per each surface is approximately 70%, and the remainder is absorbed by the mirror base material and is converted into heat. 
     FIG. 13A  shows an example of temperature changes at the projection system mirrors D and E (mirrors  7 D and  7 E in  FIG. 1 ). With reference to the projection system mirror temperature T 1  during the non-exposure period, the mirror temperatures gradually increase as the exposure starts, and they reach temperatures T 4  and T 3  and they are stabilized there. Here, in the exposure light reflecting area, the temperature rises and, as a result, even if a mirror material having a very small thermal expansion coefficient is used, at the mirror peripheral portion, the reflection surface will be shifted to such an extent that the precision of the projection system mirrors  7 A- 7 E, the illumination system mirrors  5 A- 5 D and the light source mirror  2 C, for which very strict mirror surface shape precision is required, cannot be compensated for any more. 
   If the mirror surface precision is degraded as described, for the projection system, the imaging performance on the wafer is degraded and the illuminance is lowered as well. For the illumination system, on the other hand, the target illuminance on the mask is degraded, and non-uniformness of illuminance becomes worse. For the light source mirror, the illuminance is degraded such as by defective light collection of the light source, for example. Generally, these degradations lead to deterioration of the basic performance such as exposure precision or throughput of the exposure apparatus, for example. 
   As regards the original, on the other hand, a similar problem will occur like the case of the reflection mirrors described above.  FIG. 13B  shows an example of temperature change of an original. With reference to an original&#39;s temperature T 1  during a non-exposure period, the temperature of the original surface gradually increases as the exposure starts, and it reaches a temperature T 2  and is stabilized thereat. Here, in the exposure light reflection area of the original pattern, the temperature rises and, as a result of it, even if an original mirror material having a very small thermal expansion coefficient is used, the original pattern reflection surface will be shifted. As a result of it, distortion of the original pattern, as well as pattern magnification error, will be produced, which will lead to degradation of the resolution precision. 
   SUMMARY OF THE INVENTION 
   It is accordingly an object of the present invention to provide an exposure apparatus by which at least one of the inconveniences described above can be removed or reduced. 
   In accordance with an aspect of the present invention, there is provided n exposure apparatus, comprising a light source, an illumination optical system for illuminating an original with light from the light source, a projection optical system for projecting a pattern of the original, illuminated by the illumination optical system, onto a substrate, a radiation member disposed to be opposed to a subject of temperature adjustment, which corresponds to at least one of an optical element of the illumination optical system, an optical element of the projection optical system and the original, and a control system for controlling a temperature of the projection optical system and the original, and a control system for controlling a temperature of the radiation number in accordance with a state of exposure of the subject of the temperature adjustment. 
   These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic view of a general structure of an exposure apparatus according to an embodiment of the present invention. 
       FIGS. 2A and 2B  illustrate the structure and function of projection system mirrors and temperature adjusting means for the same, according to the first embodiment of the present invention. 
       FIG. 3  illustrates the structure and function of projection system mirrors and temperature adjusting means for the same, according to a second embodiment of the present invention. 
       FIGS. 4A ,  4 B and  4 C are schematic views, respectively, showing a reticle conveying system, a reticle stage and reticle temperature adjusting means, according to a third embodiment of the present invention. 
       FIGS. 5A and 5B  are schematic views for explaining reticle alignment in the structure shown in  FIGS. 4A-4C . 
       FIGS. 6A and 6B  are a schematic view and a diagrammatic view, respectively, for explaining a reticle temperature adjustment in the structure of  FIGS. 4A-4C . 
       FIG. 7  is a graph for explaining temperature changes of a radiation temperature adjusting plate and of a reticle, in the structure of  FIGS. 4A-4C . 
       FIGS. 8A and 8B  are schematic views for explaining reticle temperature adjustment in a fourth embodiment of the present invention. 
       FIG. 9  is a flow chart for explaining the sequence of device manufacturing processes. 
       FIG. 10  is a flow chart for explaining details of a wafer process included in the procedure of  FIG. 9 . 
       FIGS. 11A and 11B  are schematic views for explaining the structure of a conventional reticle alignment mechanism. 
       FIGS. 12A and 12B  are schematic views for explaining the operation of the reticle alignment mechanism of  FIGS. 11A and 11B . 
       FIGS. 13A and 13B  are graphs, for explaining temperature changes of projection system mirrors, in the structures of  FIGS. 11A and 11B . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Preferred embodiments of the present invention will now be described with reference to the attached drawings. 
   Embodiment 1 
     FIG. 1  is a schematic view showing a general structure of an EUV exposure apparatus according to an embodiment of the present invention. As compared with the conventional structure described hereinbefore, the exposure apparatus of this embodiment comprises mirror temperature adjusting means  23  for performing radiation temperature-adjustment at a position spaced from a projection system mirror  7 C, as shown in  FIG. 2A , mirror temperature adjusting means for performing radiation temperature-adjustment at a position spaced from a projection system mirror  7 E, mirror temperature detecting means  25  for measuring the temperature of the mirror  7 C, mirror temperature detecting means  26  for measuring the temperature of the mirror  7 E, and temperature control means for determining a set temperature for the mirror temperature adjusting means  23  and  24  in accordance with temperature measured values from the mirror temperature detecting means  25  and  26 . The remaining portion of this embodiment has a similar structure as that of the conventional structure. What differs from the conventional structure will be described below, mainly. 
   Referring to  FIG. 2A , during a non-exposure period of the exposure apparatus, exposure heat quantities to be incident on the mirrors  7 C and  7 E, respectively, are predicted and, in accordance with the predicted temperature rise of the mirrors, the mirrors  7 C and  7 E are preheated by radiation temperature-adjustment from their reflection surface side, by use of the mirror temperature adjusting means  23  and  24 . Here, the temperature of the mirrors themselves are detected by using the mirror temperature detecting means  25  and  26 , respectively, and the temperatures of the mirror temperature adjusting means  23  and  24  are controlled by use of the temperature control means  27 . 
     FIG. 2B  illustrates details of the temperature control, wherein the axis of abscissa depicts the time elapsed as the process changes over from the non-exposure state to the exposure state, and wherein the axis of ordinate depicts temperatures at various positions. 
   From a predicted incidence light quantity in the exposure period, per unit time, on each mirror, a predicted temperature rise of each mirror is calculated. Then, during the non-exposure period, the set temperature for the mirror temperature adjusting means  23  and  24  are placed at temperatures T 7  and T 6 , respectively. Here, the temperatures of the mirrors are specified by the mirror temperature detecting means  25  and  26 , respectively, as T 5  and T 4 , respectively. If the temperatures of the mirrors  7 C and  7 E during the non-exposure period do not reach the temperatures T 5  and T 4  for the exposure period, the set temperatures of the temperature adjusting means  23  and  24  are negative-feedback controlled on the basis of the measured temperatures of the mirror temperature detecting means  25  and  26 . Alternatively, on the basis of the past exposure hysteresis and temperature hysteresis, the set temperatures T 7  and T 6  of the mirror temperature adjusting means  23  and  24  may be corrected. 
   During the exposure period, on the other hand, the exposure light from the light source  2 A is reflected by the mirrors  5 A- 5 D of the exposure light introducing unit and the mirrors  7 A- 7 E of the reduction projection mirror optical system, each mirror having a reflection surface formed with a Mo—Si multilayered film applied by vapor deposition or sputtering. The reflectance of each mirror is approximately 70%, and the remainder is absorbed by the mirror base material and is converted into heat. Thus, the temperature at the exposure light reflection area rises. In this embodiment, in consideration of this, the temperature difference between the non-exposure period and the exposure period is prevented. To this end, simultaneously with the start of exposure, the temperatures of the mirror temperature adjusting means  23  and  24  are gradually lowered from T 7  and T 6 , respectively, so that, in the steady state of the exposure period, the temperatures of the mirror temperature adjusting means  23  and  24  become lower than the mirror temperatures. By doing so, the mirror temperatures are balanced with the temperature rise due to the incidence light quantity of exposure light and, as a result of this, the mirror temperatures can be maintained constant. 
   In this embodiment, as described above, the temperature of each reflection mirror during the non-exposure period is made substantially at the same level as that during the exposure period and, by doing so, transitional temperature change of the reflection mirror at the start of exposure is avoided. Thus, distortion of the reflection mirror can be prevented, and degradation of aberration due to the mirror temperature change at the start of exposure can be avoided. Therefore, a high-precision exposure apparatus can be accomplished. The concept of this embodiment is applicable to any of reflection mirrors  2 C,  5 A- 5 D, and  7 A- 7 E from the light source  2 A to the wafer  8 A, and the reflection mirror distortion can be similarly prevented. Additionally, the invention is applicable not only to a reflection mirror, but also to an original (reticle)  6 A. On that occasion, transitional temperature change of the original at the start of exposure can be avoided, and distortion of the original can be prevented. Thus, pattern distortion of the original resulting from temperature change of the original at the start of exposure can be prevented, and a high precision exposure apparatus can be accomplished. 
   Embodiment 2 
     FIG. 3  shows a second embodiment, which is directed to an example wherein, for optical axis adjustment of a reduction projection mirror system  7  or aberration adjustment of reflection mirrors, to be performed on the main assembly of an exposure apparatus, temperature adjustment by radiation is carried out to the mirrors. 
   In  FIG. 3 , in relation to mirrors  7 A and  7 D, there is mirror temperature adjusting means  28  disposed spaced from these mirrors. In relation to a mirror  7 B, there is mirror temperature adjusting means  37 B disposed spaced from this mirror. In relation to a mirror  7 C, there is mirror temperature adjusting means  23  disposed spaced from this mirror. In relation to a mirror  7 E, there is mirror temperature adjusting means  24  disposed spaced from this mirror. 
   There are mirror temperature detecting means  29 A,  37 A,  25 ,  29 D and  26 , associated with the mirrors  7 A- 7 E, respectively. Temperature measured values from these mirror temperature detecting means are collected to temperature control means  27 . 
   For measurement of an optical axis and aberration of the reduction projection mirror optical system  7 , a wavefront measuring light supplying fiber  30  introduces measuring light from the back of the reticle stage. The measuring light then goes out from a wavefront measuring light exit port  31 . The light from the port  31  is incident on and reflected by the mirrors  7 A- 7 E sequentially, and finally, it is received and detected by an optical axis and wavefront measuring light sensor  32 . 
   Denoted at  33  is a wavefront measured value calculating circuit for calculating the optical axis and wavefront aberration, on the basis of a signal from the sensor  32 . Denoted at  34  is a mirror corrective drive table calculating circuit that calculates a mirror corrective drive amount on the basis of an optical axis deviation and aberration remainder as calculated by the wavefront measured value calculating circuit  33 . Denoted at  35  is a mirror corrective drive means for performing corrective drive to the mirror, on the basis of a corrective drive signal from the table calculating circuit  34 . The mirror corrective drive means  35  is operable to minutely move a mirror supporting actuator (not shown) in X, Y and Z directions, thereby to enable correction of the mirror surface in translational shift directions along its plane as well as correction of minute displacement and fall of the rotational axis. Denoted at  36  is mirror measuring means for detecting a mirror corrective drive amount. 
   In the structure described above, in order to adjust the optical axis and aberration of the reduction projection mirror optical system  7 , set temperatures of respective mirror temperature adjusting means for the respective mirrors are calculated on the basis of the measured values from the mirror temperature detecting means  29 A,  37 A,  25 ,  29 D and  26 , as collected to the temperature adjustment control means  27 , as well as the set temperatures of the mirrors during the exposure period. Based on this, the temperatures of the mirror temperature adjusting means  23 ,  24 ,  28  and  38  are controlled, whereby the temperatures of the respective mirrors can be controlled to those levels corresponding to the temperatures in the exposure period. The temperature control means  27  checks whether the mirror temperatures reach the levels corresponding to the temperatures during the exposure period, and, after it is discriminated, while the reticle chuck slider  6 B of the reticle stage  6  is held retracted, the wavefront measuring light supplying fiber  30  supplies measuring light as illustrated in the drawing. Then, the measuring light goes out of the wavefront measuring light exit port  30  (from which wavefront evaluating light is provided), and the measuring light is reflected by all the reflection surfaces of the projection system mirrors, sequentially. Finally, as shown in the drawing, it is received by the optical axis and wavefront measuring light receiving sensor  32  mounted on the movable portion of the wafer stage  8 , whereby the amount of optical axis deviation of the projection system through the whole reflection mirrors as well as the amount of optical wavefront aberration of the same are measured. The optical axis and wavefront measured value obtained at the sensor  32  is applied to the wavefront measured value calculating circuit  33 , by which the optical axis and wavefront aberration corrective amount is calculated. On the basis of the thus calculated optical axis and wavefront aberration corrective amount, the mirror corrective drive table calculating circuit  34  calculates the corrective drive directions and corrective drive amounts for the mirrors  7 A- 7 E, as well as force application amounts therefor. These calculated amounts are transmitted to the mirror corrective drive control means  35  as target values. Simultaneously therewith, information from the mirror position measuring means (not shown) for measuring the position of the mirrors  7 A- 7 E are collected to the mirror measuring means  36 , whereby the relative position of the mirrors is measured. 
   By using the mirror corrective drive means  35  and the mirror measuring means  36 , the mirrors are moved to their target positions, respectively. After this, the optical axis and wavefront aberration are measured and checked again. If the optical axis and the wavefront aberration satisfy a standard level, the correction is completed. If the standard level is not satisfied, on the other hand, residual wavefront aberration is calculated by the wavefront measurement calculating circuit and the above-described correction is repeated to get the target standard level. 
   As described above, by performing the optical axis and aberration adjustment while keeping the mirror temperatures at the level corresponding to the temperatures in the exposure period, stable optical axis and aberration can be satisfied in the state equivalent to the exposure period. Namely, in accordance with this embodiment, for optical axis adjustment of a projection optical system or for aberration adjustment of reflection mirrors, the reflection mirrors are preheated by use of a radiation temperature-adjusting heater, by which optical axis adjustment or aberration adjustment in the state corresponding to the exposure operation period are assured. Thus, an exposure apparatus having small aberration production and variation during the exposure process, can be accomplished. 
   Embodiment 3 
   Referring to  FIGS. 4A-7 , a third embodiment of the present invention will be explained. In the first and second embodiments described hereinbefore, the present invention is applied with respect to temperature adjustment during the non-exposure period of the projection system mirrors. However, the invention is applicable also to an original. Thus, in this embodiment, as shown in  FIG. 4A , a temperature adjusting radiation plate  38  is provided so as to be spaced from and opposed to a position, at a side of the reticle alignment scope  15 , to which the reticle stage  6  is to be retracted. 
   The sequence of reticle replacement is illustrated in  FIGS. 4A-4C ,  5 A and  5 B. 
   Referring to  FIG. 4A , for changing original (reticles)  6 A and  6 D, initially, the original  6 D is placed on and held by a reticle alignment hand  14 , while a reticle chuck slider  6 B, having the original  6 A mounted thereon, moves to the reticle changing position. 
   Then, the reticle alignment hand  14 A is moved by the reticle alignment unit  14  from the  FIG. 4A  position, upwardly as shown in  FIG. 4B . After this, the original  6 A is transferred to the reticle alignment hand, from the reticle chuck  6 E of the reticle chuck slider  6 B. Subsequently, the reticle alignment hand is retracted downwardly and then it is rotationally moved, whereby the reticle changing is completed as shown in  FIG. 4C . 
   Next, an alignment operation for an original (reticle) with respect to the reticle stage will be explained. As shown in  FIG. 5A , an alignment operation is made to an original (reticle)  6 D having been attracted to and conveyed by a reticle alignment electrostatic chuck (not shown), which is provided on the reticle alignment hand  14 A. Namely, a positional error of the original  6 A is measured and detected by means of a reticle alignment scope  15  and from a relative alignment error with respect to a reticle alignment mark  15 A. Then, an original alignment control circuit  37  controllably drives the reticle alignment unit  14  to perform alignment operation through the reticle alignment hand  14 A, with respect to the X and Y directions (directions along the plane) and the ωZ direction (rotational direction about the Z axis), whereby alignment of the original  6 D is accomplished. At the moment whereat the alignment of the original  6 D is completed, the bottom face (upper surface) of the original  6 D is attracted and clamped by means of a reticle chuck (electrostatic chuck)  6 E of the reticle chuck slider  6 B, on the basis of Coulomb&#39;s force or Johnson-Rahbek force. 
   The reticle chuck slider  6 B is provided with a reticle and a reticle chuck slider temperature detecting means  6 G (see  FIG. 6A ), which is arranged to detect the temperature of the original  6 D as the same is being clamped by attraction by the reticle chuck slider  6 B. 
   Referring to  FIGS. 6A ,  6 B and  7 , the preheating operation of the original (reticle)  6 D during the non-exposure period will be explained. As best seen in  FIG. 6A , the temperature adjusting radiation plate  38  is provide at a position to be opposed to the position upon the original  6 D that is retracted away from the incidence position of the exposure light  2 B. 
   Namely, the original  6 D is moved to the position to be opposed to the temperature adjusting radiation plate  38 , and the temperature of the original  6 D is measured by use of the reticle and reticle chuck slider temperature detecting means  6 G, which is provided on the reticle chuck slider  6 B. The measured value is transmitted to a reticle and reticle chuck slider temperature detecting circuit  39 , and a corrective temperature amount is calculated. At the same time, from the exposure amount information of light to be incident on an original (reticle), incidence heat quantity information concerning the heat quantity to be incident on the original is predicted. On the basis of the exposure amount information and the incidence heat quantity information, a reticle radiation temperature-adjustment control means  40  determines a temperature-adjusting set temperature for the reticle  6 D during the non-exposure period. Then, a reticle radiation temperature-adjusting means  42  controls the temperature of the temperature adjusting radiation plate  38 . 
   In order to assure that radiation temperature-adjustment from the temperature adjusting plate  38  to an effective pattern region (exposure light incidence region) of the original  6 D, the reticle chuck slider  6 B reciprocally moves relative to the temperature adjusting radiation plate  38 . 
   Through the temperature adjustment of the original (reticle) during the non-exposure period as described above, preheating is carried out while taking the temperature T 9  of the radiation temperature-adjusting plate  38  in the non-exposure period as a set temperature ( FIG. 7 ) and, as a result, the temperature of the original (reticle)  6 D is brought to the level T 8 . From this state, as the exposure starts, the set temperature of the radiation temperature-adjusting plate  38  is lowered in accordance with the temperature rise of the original (reticle) due to irradiation with exposure light. Namely, temperature control is done so that the sum of the heat quantity from the radiation temperature-adjusting plate  38  and the heat quantity by the exposure light is kept substantially constant. With this temperature control, even after a start of exposure, the temperature of the original  6 D can be maintained at a constant level T 8 . 
   With this procedure, transitional distortion or change in shape of the original (reticle), during a transitional period from the non-exposure state to the start of exposure, can be avoided effectively. Thus, a shift of magnification of the original (reticle) pattern, for example, can be prevented. 
   Embodiment 4 
   In the third embodiment described above, the original is relatively reciprocally moved relative to the temperature adjusting radiation plate  38  of a relatively small size, to assure uniform temperature adjustment. However, as shown in  FIG. 8A , a temperature adjusting radiation plate  43  of a relatively large size, corresponding to the effective area of the original (reticle) pattern, may be provided at a position to be opposed to and spaced from the original as the same is retracted. This enables temperature adjustment while the reticle  6 D is held stationary. 
   Embodiment 5 
   In the first to fourth embodiments described hereinbefore, radiation temperature-adjusting means is used as preheating means for the mirror temperature and the mask temperature. As an alternative for keeping the mirror temperature or mask temperature constant, exposure light may be irradiated without loading a substrate (wafer), during the non-exposure period, to thereby preheat the mirror temperature or the mask temperature to a level corresponding to the temperature during the exposure period. On that occasion, the original (reticle) stage as well may perform approximately the same operation as done in the exposure period, by which preheating temperature adjustment of the original (reticle) can be achieved. 
   Embodiment 6 
   Next, an embodiment of a device manufacturing method, which uses an exposure apparatus described above, will be explained. 
     FIG. 9  is a flow chart for explaining the procedure of manufacturing various microdevices such as semiconductor chips (e.g., ICs or LSIs), liquid crystal panels, CCDs, thin film magnetic heads or micro-machines, for example. Step  1  is a design process for designing a circuit of a semiconductor device. Step  2  is a process for making a mask on the basis of the circuit pattern design. Step  3  is a process for preparing a wafer by using a material such as silicon. Step  4  is a wafer process, which is called a pre-process, wherein, by using the thus prepared mask and wafer, a circuit is formed on the wafer in practice, in accordance with lithography. Step  5 , subsequent to this, is an assembling step, which is called a post-process, wherein the wafer having been process at step  4  is formed into semiconductor chips. This step includes an assembling (dicing and bonding) process and a packaging (chip sealing) process. Step  6  is an inspection step wherein an operation check, a durability check, and so on, for the semiconductor devices produced by step  5 , are carried out. With these processes, semiconductor devices are produced, and they are shipped (step  7 ). 
     FIG. 10  is a flow chart for explaining details of the wafer process. Step  11  is an oxidation process for oxidizing the surface of a wafer. Step  12  is a CVD process for forming an insulating film on the wafer surface. Step  13  is an electrode forming process for forming electrodes upon the wafer by vapor deposition. Step  14  is an ion implanting process for implanting ions to the wafer. Step  15  is a resist process for applying a resist (photosensitive material) to the wafer. Step  16  is an exposure process for printing, by exposure, the circuit pattern of the mask on the wafer through the exposure apparatus described above. Step  17  is a developing process for developing the exposed wafer. Step  18  is an etching process for removing portions other than the developed resist image. Step  19  is a resist separation process for separating the resist material remaining on the wafer after being subjected to the etching process. By repeating these processes, circuit patterns are superposedly formed on the wafer. With these processes, high density microdevices can be manufactured. 
   The present invention can be embodied in various forms, examples of which are as follows. 
   (1) An exposure apparatus wherein a pattern formed on an original is projected onto a substrate through a projection optical system while both of the original and the substrate or only the substrate is relatively moved relative to the projection optical system by use of a stage system, whereby the pattern of the original is repeatedly transferred to the substrate, characterized in that radiation temperature-adjusting means is provided at a position spaced with respect to a reflection mirror, which is provided in a projection optical system, in an illumination optical system for supplying exposure light to the projecting optical system, or in an exposure light source unit, and that the temperature of the radiation temperature-adjusting means is made variable approximately in synchronism with a temperature change of the reflection mirror between a non-exposure period and an exposure period. 
   (2) An exposure apparatus wherein a pattern formed on an original is projected onto a substrate through a projection optical system while both of the original and the substrate or only the substrate is relatively moved relative the projection optical system by use of a stage system, whereby the pattern of the original is repeatedly transferred to the substrate, characterized in that radiation temperature-adjusting means is provided at a position spaced from the surface of the original, and that the temperature of the radiation temperature-adjusting means is made variable approximately in synchronism with a temperature change of the reflection mirror between a non-exposure period and an exposure period. 
   (3) An exposure apparatus according to items (1) or (2), wherein a set temperature of the radiation temperature-adjusting means is made variable in accordance with an exposure amount, an exposure view angle, an exposure time or any other exposure condition variable that may change the temperature of the reflection mirror or of the original. 
   (4) An exposure apparatus according to item (2), wherein the radiation temperature-adjusting means is provided at a position spaced from the original, off an exposure light introducing position of an original stage, and wherein, during the non-exposure period, the original stage moves the original to a position opposed to the radiation means to perform the radiation temperature adjustment. 
   (5) An exposure apparatus according to item (4), wherein, when the original is moved to a position opposed to the radiation means during the non-exposure period, the original stage is moved along the plane of the original surface, relative to the radiation temperature-adjusting means. 
   (6) An exposure apparatus wherein a pattern formed on an original is projected onto a substrate through a projection optical system while both of the original and the substrate or only the substrate is relatively moved relative to the projection optical system by use of a stage system, whereby the pattern of the original is repeatedly transferred to the substrate, characterized in that radiation temperature-adjusting means is provided to be spaced with respect to a reflection mirror, which is provided in a projection optical system, in an illumination optical system for supplying exposure light to the projection optical system, or in an exposure light unit, that one of optical axis measuring means and wavefront aberration measuring means is provided in relation to a reflection mirror, which is provided in the projection optical system, in the illumination optical system for supplying exposure light to the projection optical system, or in the exposure light source unit, and that when the optical axis adjustment or the wavefront aberration adjustment is carried out during a non-exposure period, temperature adjustment is performed to the reflection mirror through the radiation temperature-adjusting means. 
   (7) An exposure apparatus according to time (6), wherein a corrective drive amount of reflection mirror position corrective drive means or reflection mirror shape correcting means is calculated and controlled on the basis of a measured value of the radiation temperature-adjusting means and the optical axis measuring means or the wavefront aberration measuring means. 
   In accordance with these aspects of the present invention, a reflection mirror or an original placed at a light path of exposure light from an exposure light source to a substrate to be exposed is preheated by use of a radiation temperature-adjusting heater, for example, during a period in which the exposure light is not projected to the reflection mirror or the original. This effectively suppresses the temperature change of the reflection mirror or of the original, at the start of exposure, such that distortion of the original pattern or of the reflection mirror can be suppressed, and that degradation of aberration and distortion of a pattern of the original due to the mirror temperature change at the start of exposure can be avoided effectively. 
   Furthermore, at the optical axis adjustment of the projection optical system or at the aberration adjustment of the reflection mirror, the reflection mirror may be preheated by use of a radiation temperature-adjusting heater, for example. This enables optical axis adjustment or aberration adjustment in a condition equivalent to that of the exposure operation. Thus, degradation of aberration and pattern distortion of the original, resulting from the mirror temperature change at the start of exposure, can be avoided. 
   In accordance with an aspect of the present invention, a high-precision exposure apparatus can be accomplished, by which translation temperature change of an optical element or of an original at the start of exposure can be avoided, by which distortion of the optical element or of the original pattern can be avoided, and by which degradation of aberration and pattern distortion of the original due to the temperature change of the optical element at the start of exposure can be prevented. Furthermore, at the optical axis adjustment of an illumination optical system or projection optical system or at the aberration adjustment of each optical element, the optical element may be temperature adjusted by preheating, using a radiation temperature-adjusting heater, for example. This enables optical axis adjustment or aberration adjustment in a condition equivalent to that of an exposure operation. Thus, an exposure apparatus, having small aberration and a small change in the period of exposure, can be accomplished. 
   While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims. 
   This application claims priority from Japanese Patent Application No. 2003-414579 filed Dec. 12, 2003, which is hereby incorporated by reference.