JPH104055A - Automatic focusing device and manufacture of device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an automatic focusing device which is capable of very accurately detecting the surface position of a plate-like work by a method wherein a light projecting means which irradiates the platelike work placed on a stage movable in a direction vertical to the light axis of a projection optical system with light spots, a photodetecting means which detects a reflected light flux from the platelike work, and a computing device which computes signals outputted from the photodetecting means are properly set in configuration. SOLUTION: Light rays projected from a light source 4 are turned to a collimated light flux through a lighting lens 5 to irradiate an aperture mask 6 where pinholes are provided. The images of the pinholes provided to the mask 6 are formed on a wafer 2 by an image forming lens 7 and a deflecting mirror 8. Light fluxes reflected at measurement points on a wafer 2 are changed in the direction of travel by the deflecting mirror 9 and made to impinge on a position detecting detector 11 where photodetectors are two-dimensionally arranged through the intermediary of a detection lens 10. Signals outputted from the position detecting device 11 are formed into the surface position data of the measurement points by a surface position detecting means 14, the surface position data of the measurement points are inputted into a control means 13, the command signals outputted from the control means 13 are inputted into a stage drive means 12, and a wafer stage 3 is driven by the stage drive means 12 of servo mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focusing apparatus and a projection exposure apparatus using the same, and more particularly, to a miniature projection exposure apparatus (stepper) for manufacturing semiconductor devices, the semiconductor mounted on a wafer stage. This is suitable when each exposure area of the wafer is focused on the focal plane of the reduction projection lens system (projection optical system).

[0002]

2. Description of the Related Art At present, circuit patterns have been miniaturized in accordance with the high integration of VLSIs, and accordingly, the reduction projection lens system of a stepper has been made higher in NA, and this has been accompanied. The permissible depth of focus of the lens system in the circuit pattern transfer process has become narrower. In addition, the size of the exposed area to be exposed by the reduction projection lens system tends to be increased.

In order to make it possible to transfer a good circuit pattern over the entire area to be exposed which has been enlarged, it is necessary to ensure that the exposure of the wafer is within the allowable depth of focus of the reduction projection lens system. It is necessary to position the entire area (shot).

In order to achieve this, the position and inclination of the wafer surface relative to the focal plane of the reduction projection lens system, that is, the plane on which the circuit pattern image of the reticle is focused, are detected with high accuracy, and the position and inclination of the wafer surface are determined. It is important to make adjustments.

[0005] As a method of detecting the surface position of the wafer surface in the stepper, a method of detecting the surface position of a plurality of positions on the wafer surface using an air microsensor and obtaining the position of the wafer surface based on the detection result, or A light projection type detection optical system (oblique incidence optical system) is used to detect the position shift of the reflection point of the reflected light from the wafer surface as the position shift of the reflected light on the sensor by causing the light beam to enter the surface obliquely. Thus, a method of detecting the surface position of the wafer surface is known.

[0006]

When detecting surface position information at a plurality of measurement points on a wafer surface using a conventional oblique incidence optical system, for example, a TEG (Test) in which the measurement points are test patterns on the wafer surface is used. If it is located on a scribe on the wafer surface or an element group, the light intensity distribution of the reflected light from the scribe will be deformed and a detection error will occur.

FIG. 7 shows that a light spot L passing through a pinhole (opening) M provided in a mask 6 is a chip C on the wafer surface 2.
FIG. 4 is an explanatory diagram of an optical path when light enters a scribe area SC between H1 and CH2, is reflected from the surface, and enters a light receiving surface (position detection element) D.

As shown in FIG. 1, the intensity of the spot light of the light flux L which passes through the opening M of the mask 6 and is obliquely incident on the wafer 2 becomes light and dark light indicated by a wavelength SI. When multi-chip exposure for printing a plurality of chip patterns in one exposure is performed, and the reflection position (detection point) of the spot light on the wafer is located on a scribe which is a margin between chips, a reflection surface as on the chip If is flat, light is light LT
However, the light reflected on the scribe becomes light LS because the reflection surface is inclined, and the image formation position is shifted at the position of the position detection element D.

[0009] Due to the shift of the imaging position between the light LT and the light LS,
When the light received by the position detection element D on the light receiving surface D is photoelectrically converted, the output signal waveform is distorted like the waveform SO, and the data at the detection position includes an error. This error has a problem that the measurement error at each exposure chip position largely fluctuates because the scribe shape at each exposure chip position on the wafer surface is not formed stably, and cannot be corrected as a constant offset value. .

If the detection position of the surface position detecting means overlaps the scribe, the signal from the scribe area is distorted and cannot be separated, so that the accurate surface position cannot be measured, and the wafer cannot be measured. There is a problem that the surface cannot be set at the best image forming plane position of the projection optical system, and good transfer of the reticle pattern cannot be performed. This is the same when the measurement point is located at the TEG on the wafer surface.

According to the present invention, there is provided a light projecting means for projecting a plurality of appropriately set light spots onto a flat object placed on a stage movable along a direction orthogonal to the optical axis of a projection optical system. By appropriately setting the configuration of the light receiving means for receiving the reflected light beam from the flat object, and the arithmetic means for arithmetically processing the output signal from the light receiving means, the scribe generated in the multi-chip configuration in the exposure area can be obtained. An automatic focusing device which can detect a surface position with high accuracy and set a flat object at a predetermined position even if there is an area where the detection signal is deformed and the surface position detection accuracy is reduced as described above. And a projection exposure apparatus using the same.

In addition, according to the present invention, in a projection exposure apparatus for projecting a pattern on a reticle surface onto a wafer surface by a projection optical system, a detection error caused by projection of a scribe line on the wafer surface is removed, and surface position information on the wafer surface is removed. Is detected with high accuracy,
It is an object of the present invention to provide an automatic focusing apparatus capable of accurately positioning a wafer on a focal plane of a projection optical system and a projection exposure apparatus using the same.

[0013]

According to the present invention, there is provided an automatic focusing apparatus comprising: (1-1) a device which projects a pattern on a reticle surface onto a wafer surface along a direction substantially orthogonal to an optical axis of a projection optical system; Place the wafer on a stage that can move in the three-dimensional direction,
A predetermined surface of the wafer is set as an image plane of the projection optical system, the predetermined surface is irradiated with a plurality of spot lights from a light projecting unit, and reflected light based on the plurality of spot lights from the predetermined surface is converted into a photoelectric conversion unit. And selecting a predetermined signal from a plurality of signals obtained by the photoelectric conversion means from a chip layout on a wafer based on a chip configuration on the reticle and a positional relationship between the plurality of spot lights. The surface position information of the predetermined surface is detected by the calculating means using the predetermined signal, and the predetermined surface is set as the focal plane of the projection optical system based on the signal from the calculating means.

In particular, (1-1-1) the wafer is placed on a stage movable two-dimensionally along a direction substantially orthogonal to the optical axis of a projection optical system for projecting a pattern on the reticle surface onto the wafer surface. And setting a predetermined surface of the wafer as an image plane of the projection optical system, irradiating the predetermined surface with a plurality of spot lights from a light projecting unit, and reflecting light based on the plurality of spot lights from the predetermined surface. A predetermined signal is detected from the plurality of signals detected by the photoelectric conversion unit and selected from a plurality of signals obtained by the photoelectric conversion unit based on a test pattern layout on a wafer based on a test pattern on the reticle and a positional relationship between the plurality of spot lights. Detecting surface position information of the predetermined surface by using the selected predetermined signal by a computing unit, and setting the predetermined surface as a focal plane of the projection optical system based on a signal from the computing unit; (1-1-2) One of the plurality of spot lights One is composed of a multi-spot consisting of a plurality of spots repeating light and dark, and the calculating means performs weighting calculation on a plurality of signals respectively obtained by the photoelectric conversion means based on the multi-spot; (1- 1-3) The measurement position formed from the plurality of spots on the predetermined surface is distance information from a center point of a predetermined image height of the projection optical system, and the distance information is used when selecting the predetermined signal. It is characterized by that.

In the projection exposure apparatus of the present invention, (2-1) the reticle and the wafer are aligned in the optical axis direction of the projection optical system by using the automatic focusing apparatus of the constitutional requirement (1-1). The pattern on the reticle surface is projected and exposed on the wafer surface via the projection optical system.

The device manufacturing method of the present invention is characterized in that the device is manufactured using the projection exposure apparatus of the constitutional requirement (2-1).

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view showing a main part of a part of a reduction type projection exposure apparatus (stepper) provided with an automatic focusing apparatus according to the present invention.

In FIG. 1, reference numeral 1 denotes a reduction projection lens system (projection optical system), the optical axis of which is indicated by AX in the figure.
The reduction projection lens system 1 projects the circuit pattern of the reticle R by reducing it, for example, by a factor of 5 to form a circuit pattern image on its focal plane. The optical axis AX is in a relationship parallel to the z-axis direction in the figure. Reference numeral 2 denotes a wafer having a surface coated with a resist, on which a plurality of exposure regions (shots) in which the same pattern is formed in the previous exposure step are arranged.

Reference numeral 3 denotes a wafer stage on which a wafer is placed. The wafer 2 is attracted and fixed to the wafer stage 3. The wafer stage 3 includes an X stage that moves in the x-axis direction,
Y stage moving in y axis direction, z axis direction and x, y, z
It is composed of a θ-Z stage that rotates around an axis parallel to the axial direction. The x, y, and z axes are set so as to be orthogonal to each other. Therefore, by driving the wafer stage 3, the position of the surface of the wafer 2 is reduced to the size of the projection lens system 1.
In the direction of the optical axis AX and in a direction along a plane orthogonal to the optical axis AX, and also adjusts the focal plane, that is, the inclination with respect to the circuit pattern image.

Reference numerals 4 to 11 in FIG. 1 denote surface position detecting means including an oblique incidence optical system provided for detecting the surface position and inclination of the wafer 2. Reference numeral 4 denotes a light emitting diode as illumination optics, which is a high-luminance light source such as a semiconductor laser. Reference numeral 5 denotes an illumination lens.

The light emitted from the light source 4 is converted into a parallel light beam by the illumination lens 5, and an aperture mask (hereinafter referred to as a "mask") having a plurality (five) of pinholes (6a to 6e) formed therein.
I also say. ) Illuminate 6. In the figure, only two pinholes 6a and 6b are shown. The plurality of spot lights that have passed through each pinhole of the mask 6 enter the bending mirror 8 via the imaging lens 7, change the direction by the bending mirror 8, and then enter the surface of the wafer 2. .

FIG. 2 shows a central portion (projection optical system 1) of an exposed area 100 of the wafer 2 with five spot lights passing through the mask 6.
FIG. 5 is an explanatory view when irradiating five locations 41 to 45 including the optical axis (on the optical axis). FIG. 6 shows a plurality of exposure areas 10 on the wafer 2 surface.
0, 100a and 100b are shown.

As shown in FIG. 2, the exposure area 100 of the wafer
Five pinholes of the mask 6 are formed in five places (41 to 45).

Here, the imaging lens 7 and the bending mirror 8 form images of a plurality of pinholes of the mask 6 on the wafer 2. The light beam that has passed through the plurality of pinholes illuminates five places (41 to 45) including the central part of the exposed area 100 of the wafer 2 as shown in FIG. 2, and is reflected at each place. That is, in the present embodiment, five pinholes are formed in the mask 6, and the position information of five measurement points (41 to 45) including the central portion thereof is measured in the exposed region 100 as described later. I have.

The luminous flux reflected at each of the measurement points (41 to 45) on the wafer 2 is changed in direction by a bending mirror 9, and then, via a detection lens 10, on a position detecting element 11 in which light receiving elements are two-dimensionally arranged. Incident on. Here, the detection lens 10 forms an image of a pinhole of the mask 6 on the position detection element 11 in cooperation with the imaging lens 7, the bending mirror 8, the wafer 2, and the bending mirror 9. That is, the mask 6, the wafer 2, and the position detecting element 11 are optically conjugate with each other. FIG.
However, when optical arrangement is difficult, a plurality of position detecting elements 11 may be separately arranged corresponding to the respective pinholes.

The position detecting element 11 comprises a two-dimensional CCD or a line sensor, and independently detects the incident positions of a plurality of light beams through a plurality of pinholes on the light receiving surface of the position detecting element 11. Is possible. Since the change in the position of the wafer 2 in the direction of the optical axis AX of the reduction projection lens system 1 can be detected as a deviation of the incident positions of a plurality of light beams on the position detecting element 11, the five positions in the exposure area 100 on the wafer 2 can be detected. The position of the wafer surface at the measurement points 41 to 45 in the optical axis AX direction can be detected based on the output signal from the position detection element 11. The output signal from the position detecting element 11 is input to the control means 13 by forming the surface position data Zi (i = 1 to 5) of each measuring point by the surface position detecting means 14.

The displacement of the wafer stage 3 in the x-axis and y-axis directions is measured by a known method using a reference mirror 15 and a laser interferometer 17 provided on the wafer stage 3, and a signal indicating the amount of displacement of the wafer stage 3 is obtained. From the laser interferometer 17 to the control means 13 via a signal line. The movement of the wafer stage 3 is controlled by a stage driving unit 12, which receives a command signal from a control unit 13 via a signal line and servo-drives the wafer stage 3 in response to this signal. I have.

In this embodiment, for example, as shown in FIG.
The wafer stage 3 is moved so that the first exposure area 100a on the wafer 2 is directly below the reduction projection lens system 1, and the first exposure area 100a is aligned with the reticle pattern. After the alignment is completed, the surface position detecting means (4 to
11), the surface positions of the five measurement points (41 to 45) of the first exposed area 100a are detected, and the position detecting element 1
The surface position detecting means 14 forms the surface position data Zi (i = 1 to 5) of each measurement point based on the output signal from 1 and sends the information to the control means 13.

The control means 13 selects predetermined surface position data from the five surface position data (position information) Zi (i = 1 to 5) by a method described later, and based on the selected surface position data, The least square plane of (the position of) one exposure area 100a is obtained, and the distance between the least square plane of the wafer 2 and the reticle pattern image in the optical axis AX direction and the direction and amount of tilt of the wafer 2 are calculated.

The position z of the least square plane is

[0031]

(Equation 1) It satisfies.

The control means 13 inputs a command signal corresponding to the calculation result to the stage driving means 12, and the stage driving means 12 controls the optical axis AX of the wafer 2 on the wafer stage 3.
The position and inclination of the direction are adjusted (corrected).

As a result, the surface of the wafer 2, that is, the first exposure area 100a is positioned on the best image forming plane (focal plane) of the reduction projection lens system 1. After the adjustment of the surface position, the first exposed area 100a is exposed to transfer a circuit pattern image.

After the exposure of the first exposed area 100a is completed, the wafer stage 3 is driven so that the second exposed area 100b on the wafer 2 is located immediately below the reduction projection lens system 1.

Next, in the present embodiment, when calculating the position of the wafer surface from the signal of the reflected light from the wafer 2, the position of the scribe in the exposure area is calculated from the layout information of the chip, and the influence of the calculation is obtained. A method will be described in which the influence of scribe is removed by selecting and calculating a signal that does not exist, and an accurate wafer surface position and a least square plane are detected.

The present embodiment is characterized in that an output signal having distortion, such as the output signal SO in FIG. 7, that is, a measurement point on a scribe is determined from shot layout information, and calculation is performed without using the signal. .

Next, a method of positioning the wafer 2 on the best imaging plane (focal plane) of the reduction projection lens system 1 in this embodiment will be described with reference to the flowchart of FIG.

In step S001, chip size and scribe position information are used as chip layout information by the control means 13.
To enter. In step S002, areas such as chips, scribes, and test patterns (TEG) are calculated from the chip layout information, and the positional relationship with measurement points is obtained. A measurement point overlapping a region that adversely affects a signal such as scribe or TEG is not used as an invalid signal. In step S003, the wafer 2 is loaded onto the wafer stage 3 and is suction-fixed to the wafer chuck.

In step S004, the wafer stage 3 is driven such that the center of the shot to be exposed is located at the center of the optical axis AX of the projection lens 1. Reticle R after driving in step S005
And the exposure shot are aligned.

In step S006, position information Z1 to Z5 on the wafer surface at the measurement points (41 to 45) is measured. In step S007, a least-square plane is calculated by excluding the invalid signal obtained in step S002 among the positional information Z1 to Z5 on the wafer surface. In step S008, the inclination and height of the wafer stage 3 are driven so that the least square plane and the image plane of the projection lens 1 match. After the difference between the focal planes of the wafer 2 and the projection lens 1 has been corrected in step S009, post-exposure is performed.

In step S010, it is determined whether or not exposure of all shots has been completed. If not, the process proceeds to step S004 and steps S004 to S009 are repeated.

In step S011, the wafer 2 is detached from the wafer chuck and carried out.

Next, the processing method in steps S002 and S007 will be described with reference to FIG.

FIG. 4A is a diagram showing the relationship between the exposure area and the spot positions of chips, scribes, and signals when detecting the surface position of a multi-chip configuration having two chip patterns in the exposure area 100. For example, the output signal from the area 42 located in the normal chip is as shown in S42, but the output signal from the area 41 located on the scribe SC is distorted as in S41. Therefore, in step S002, a scribe area excluding the chip area obtained by the chip layout from the exposure area is obtained, and a signal overlapping the scribe area SC like the measurement area 41 is specified so as not to be used as an invalid signal.

FIG. 4B is an explanatory diagram when a test pattern (TEG) is adjacent to one chip pattern in the exposure area 100 and the measurement spots 42 and 43 are located in that area. . Also in FIG. 4B, distortion occurs in the output signal S42 (S43) from the measurement spots 42 and 43. Also at this time, the TEG area is obtained from the chip layout, and the signals S42 and S43 overlapping this area are not used. In the following, a case where the signal S41 overlapping the scribe area is not used will be described as an example.

Next, in step S007, the least squares surface is calculated. As a result of not using the measurement value Z1 from the invalid signal S41 among the measurement values Zi (i = 1 to 5), the measurement value Zi (i = 2 to 2) is obtained.
5) Surface calculation is performed at the four points. Thus, by specifying the spot affected by the scribe and selecting the processing signal, the least squares surface is calculated with high accuracy, and the surface position information and the height information of the wafer W are measured without error.

Next, a second embodiment of the present invention will be described. The present embodiment is characterized in that one measurement point in the exposure area 100 is irradiated with a plurality (five) of spots (multi-spots).

As shown in FIG. 3, the mask 6 is incident on the five regions 71 to 75 of the region to be exposed 100 in a multi-spot with a set of five pinholes.

FIG. 5 shows the state of the light spot in the exposed area 100 when the measurement spot is replaced with a multi-spot. The state of the area 71 at this time is shown in FIG. 8 corresponding to FIG.

Now, five light signals P1 to P5 obtained from the measurement area 71 will be described. Although the optical signal P3 is a distorted signal due to the resist surface shape on the scribe SC, the optical signals P1, P2, P4, and P5 are distorted because they are not affected by the resist surface shape on the scribe SC. Not a signal.

In this embodiment, in this case, the optical signals P1,
Surface position information is detected using only P2, P4, and P5. Thus, by specifying the spot affected by the scribe SC and selecting a processing signal, the least square plane can be calculated without reducing the number of measurement points, and the surface height of the wafer W is measured without error. As described above, in the present embodiment, it is possible to effectively prevent the surface calculation accuracy from being lowered due to the influence of the scribe.

Next, a third embodiment of the present invention will be described. In the present embodiment, the light spot to be incident on each measurement position in the exposure area is a multi-spot where light and dark are repeated, and a weighting operation is performed based on each peak value to obtain measurement position detection data.

The present embodiment has a processing method for preventing calculation accuracy from being reduced due to the effect of scribing without inputting shot layout information. Next, referring to FIGS. 5 and 8,
This processing method will be described. As shown in FIG. 5, the light signal P3 incident on the scribe SC scatters light because the resist on the reflection surface has an irregular surface shape, and the peak value decreases. Utilizing this, when the measurement value P ₀ of the measurement point is obtained, the measurement value Pi of each optical signal of the signal is obtained.
(I = 1 to 5) is weighted by each peak value Mi (i = 1 to 5).

[0054]

(Equation 2) By having such a processing method, it is possible to prevent the accuracy of surface calculation from lowering due to the effect of scribing.

Next, a fourth embodiment of the present invention will be described. In the present embodiment, when the position coordinates of the measurement position are actually measured and held as a reference position, for example, a distance (deviation amount) from the center point of the image height of the projection lens, this distance information is selected and calculated for each measurement position. Used for

In the surface position detecting device, an actual measurement point may have a deviation (offset) of about 1 mm from the center of the exposure position with respect to the design value due to an error in the mounting position of the position detecting element (sensor) 11 or the like. Since the width of the scribe is at most about 0.2 mm, accurate determination may not be performed unless this offset is taken into account. Thus, the present embodiment is characterized in that the offset amount of the measurement point position is measured and held in advance, and the accurate position is specified, thereby determining the overlap between the measurement position and the scribe position with high accuracy.

An embodiment of the offset measurement will be described below.
First, a test pattern having a step at a predetermined position in the exposure area is created, and the pattern is brought to the lens image plane.
When the test pattern is measured by the surface position detecting device while moving stepwise in the xy plane, the step shape can be measured. The measured step shape is shifted by the offset of the surface position detecting device. Since the position of the step in the test pattern is known as a position from the center of the projection lens by performing alignment, the offset amount of the surface position detecting device is measured by comparing with the measured step shape. By holding the measured offset amount, an accurate measurement point position is specified, and highly accurate determination is possible.

Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described. FIG. 10 shows a flow of manufacturing a semiconductor device (a semiconductor chip such as an IC or an LSI, or a liquid crystal panel or a CCD).

In step 1 (circuit design), a circuit of a semiconductor device is designed. Step 2 is a process for making a mask on the basis of the circuit pattern design. On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is referred to as a preprocess, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer.

The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in step 4, and includes an assembly process (dicing and bonding) and a packaging process (chip encapsulation). And the like. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 11 shows a detailed flow of the wafer process.

In step 11 (oxidation), the surface of the wafer is oxidized. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. In step 15 (resist processing), a photosensitive agent is applied to the wafer.
Step 16 (exposure) uses the above-described exposure apparatus to print and expose the circuit pattern of the mask onto the wafer.

In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist are removed. In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of the present embodiment, it is possible to easily manufacture a highly integrated semiconductor device which has been conventionally difficult to manufacture.

[0065]

As described above, according to the present invention, a plurality of appropriately set light spots are applied to a flat object placed on a stage movable along a direction orthogonal to the optical axis of the projection optical system. By appropriately setting the configuration of the light emitting means for irradiating, the light receiving means for receiving the reflected light beam from the flat object, and the arithmetic means for arithmetically processing the output signal from the light receiving means, the exposure area can be adjusted. Even if there is a region that deforms the detection signal and lowers the surface position detection accuracy like a scribe that occurs in a multi-chip configuration, the surface position is detected with high accuracy, and the flat object is set at a predetermined position. And a projection exposure apparatus using the same.

In addition, according to the present invention, in a projection exposure apparatus for projecting a pattern on a reticle surface onto a wafer surface by a projection optical system, a detection error caused by projection of a scribe line on the wafer surface is removed. It is possible to achieve an automatic focusing apparatus capable of detecting position information with high accuracy and accurately aligning a wafer with a focal plane of a projection optical system, and a projection exposure apparatus using the same.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a main part of a first embodiment when an automatic focusing apparatus of the present invention is applied to a reduction projection exposure apparatus.

FIG. 2 is an explanatory diagram showing an arrangement of each measurement point set in a region to be exposed;

FIG. 3 is an explanatory diagram showing an arrangement of measurement points (multi-spots) set in a region to be exposed;

FIG. 4 is an explanatory diagram illustrating a measurement signal when an exposure region has a multi-chip configuration.

FIG. 5 is a view for explaining a measurement signal (multi-spot) when the exposure region has a multi-chip configuration.

FIG. 6 is an explanatory diagram showing an arrangement of a region to be exposed (shot) on a wafer;

FIG. 7 is an explanatory view for explaining that a light beam is bent and a processing signal is distorted when a detection light projection position on a wafer of a detection optical system is positioned in a margin (scribe) between chips.

FIG. 8 is an explanatory diagram for explaining a processing signal distortion and a processing method due to the influence of scribing when the multi-spot detection optical system implemented in the present invention is adapted to a shot having a multi-chip configuration.

FIG. 9 is a flowchart illustrating an example of a surface position adjustment operation using the surface position detection method according to the present invention.

FIG. 10 is a flowchart of a device manufacturing method of the present invention.

FIG. 11 is a flowchart of a device manufacturing method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Projection optical system 2 Wafer 3 Wafer stage 4 Light source 5 Illumination lens 6 Mask 7 Imaging lens 8, 9 Mirror 10 Detection lens 11 Position detection element 12 Stage driving means 13 Control means 14 Surface position detection means 100 Exposure area

Claims (6)

[Claims] 1. A projection optical system for projecting a pattern on a reticle surface onto a wafer surface along a direction substantially orthogonal to an optical axis of a projection optical system.
A wafer is placed on a stage movable in a three-dimensional direction, a predetermined surface of the wafer is set as an image plane of the projection optical system, and the predetermined surface is irradiated with a plurality of spot lights from a light projecting unit. The reflected light based on the plurality of spot lights from the plurality of spots is detected by the photoelectric conversion unit, and the chip layout on the wafer based on the chip configuration on the reticle and the plurality of spots are selected from the plurality of signals obtained by the photoelectric conversion unit. A predetermined signal is selected based on the positional relationship of the light, surface position information of the predetermined surface is detected by the arithmetic unit using the selected predetermined signal, and the predetermined surface is projected based on the signal from the arithmetic unit. An automatic focusing device wherein the focal point of the optical system is set. 2. A projection optical system for projecting a pattern on a reticle surface onto a wafer surface along a direction substantially orthogonal to an optical axis of the projection optical system.
A wafer is placed on a stage movable in a three-dimensional direction, a predetermined surface of the wafer is set as an image plane of the projection optical system, and the predetermined surface is irradiated with a plurality of spot lights from a light projecting unit. A reflected light based on a plurality of spot lights from the plurality of spots is detected by a photoelectric conversion unit, and a test pattern layout on a wafer based on a test pattern on the reticle is selected from a plurality of signals obtained by the photoelectric conversion unit. A predetermined signal is selected from the positional relationship of the spot light, and surface position information of the predetermined surface is detected by arithmetic means using the selected predetermined signal,
An automatic focusing device, wherein the predetermined surface is set to a focal plane of the projection optical system based on a signal from the calculating means. 3. Each of the plurality of spot lights is constituted by a multi-spot consisting of a plurality of spots which repeat light and dark, and the arithmetic means is based on the multi-spot and a plurality of spots respectively obtained by the photoelectric conversion means. 3. The automatic focusing apparatus according to claim 2, wherein a weighting operation is performed on the signal. 4. A measurement position formed from a plurality of spots on the predetermined surface is set as distance information from a center point of a predetermined image height of the projection optical system, and the distance information is used when selecting the predetermined signal. 3. The automatic focusing device according to claim 2, wherein: 5. A pattern on the reticle surface by aligning a reticle and a wafer in an optical axis direction of the projection optical system using the automatic focusing device according to claim 1. Projection exposure on a wafer surface via the projection optical system. 6. A device manufacturing method, wherein a device is manufactured using the projection exposure apparatus according to claim 5.