TWI897171B - Drawing apparatus and drawing method - Google Patents

Abstract

The present invention's drawing device and method involve moving a stage with a substrate mounted on its upper surface, alternating between main scanning movements in a main scanning direction and secondary scanning movements in a secondary scanning direction, while irradiating light from a drawing portion toward the substrate to perform drawing. The main scanning direction and the secondary scanning direction intersect with each other. A linear scale integral with the stage and having graduations formed along the main scanning direction is read by a reading head to detect the relative position of the drawing portion and the stage in the main scanning direction. When the stage moves in the secondary scanning direction, the reading head is moved by an amount corresponding to the stage's movement. The present invention does not increase the size or cost of the device, and can perform stage position measurement based on the principle of a linear encoder.

Description

Drawing device and drawing method

The present invention relates to a technique for drawing patterns on substrates such as semiconductor substrates, semiconductor package substrates, printed circuit wiring substrates, and glass substrates.

Technologies for forming patterns, such as wiring patterns, on various substrates, such as semiconductor substrates, semiconductor package substrates, printed circuit boards, and glass substrates, involve irradiating a substrate with a photosensitive layer formed on its surface with light corresponding to the pattern to be formed, thereby exposing the photosensitive layer. For example, Patent Document 1 describes a drawing device that irradiates a substrate with a light beam modulated according to the pattern to be drawn, thereby drawing a predetermined pattern on the substrate. Furthermore, Patent Document 2 describes a drawing device that irradiates a substrate with exposure illumination light through a reticle corresponding to the pattern shape, thereby drawing a pattern.

In these imaging devices, local exposures are performed multiple times while varying the incident position of light to image the entire substrate. Specifically, exposures are performed by alternating between a main scan motion (moving the stage supporting the substrate in the main scan direction) and a secondary scan motion (stepping and feeding the stage in an intersecting secondary scan direction). This scanning motion is sometimes referred to as a step-and-repeat or step-and-scan method.

In order to accurately trace the substrate at the appropriate location, it is necessary to accurately measure the stage position during scanning. To this end, the technology described in Japanese Patent Publication No. 2012-169549 (Patent Document 1) employs a position measurement unit using a laser interferometer. Meanwhile, the technology described in Japanese Patent Publication No. 5035247 (Patent Document 2) measures the stage position using a linear encoder that optically reads a two-dimensional scale formed on the measuring stage.

(Invent the problem you want to solve)

Among these position measurement technologies, laser interferometry has been the predominant method to date due to its superior measurement accuracy, resolution, and long-term stability. However, as measurement accuracy is further improved, short-term fluctuations in measured values caused by ambient temperature fluctuations along the laser beam's optical path become a major source of significant error.

Meanwhile, in recent years, the performance of linear encoders has continued to improve, particularly in terms of resolution, with technologies comparable to or exceeding those of laser interferometers now becoming practical. However, linear encoder position measurement technology requires the placement of a linear scale with graduations and a readhead for reading the graduations facing each other. Therefore, in order to combine this with a step-and-repeat or step-and-scan stage movement in both the main and sub-scanning directions, as described in Patent Document 2, multiple readheads are required to cover the entire range of the stage's movement.

In particular, with increasingly finer patterns and larger substrates, multiple steps in the sub-scan direction are required for each substrate. To accommodate this range of motion, multiple read heads are required. This leads to increased device size and cost, a problem that persists in existing technologies. (Technical Solution)

The present invention has been completed in view of the above-mentioned problems. Its purpose is to enable stage position measurement based on the principle of a linear encoder in a technology that performs optical drawing while moving a stage on which a substrate is mounted, without causing an increase in the size and cost of the device.

One aspect of the present invention is a drawing device comprising: a stage capable of placing a substrate on an upper surface; a drawing unit for irradiating light onto the substrate placed on the stage to perform drawing; a first moving mechanism for moving the stage relative to the drawing unit to perform a main scanning movement in a main scanning direction and a sub-scanning movement in a sub-scanning direction intersecting the main scanning direction, wherein the main scanning direction and the sub-scanning direction are parallel to the upper surface and intersect with each other; and a position detection unit for detecting the relative position of the drawing unit and the stage in the main scanning direction. In the drawing device, the position detection unit includes: a linear scale, which is integrally provided with the carrier and has graduations formed along the main scanning direction; a reading head, which reads the graduations; and a second moving mechanism, which moves the reading head relative to the drawing unit along the sub-scanning direction; when the carrier moves in the sub-scanning direction by the first moving mechanism, the second moving mechanism moves the reading head by an amount corresponding to the amount of movement of the carrier.

In the present invention thus constructed, the position of the stage in the main scanning direction is detected by a readhead reading the graduations (dimensions) of a linear scale extending in the main scanning direction and moving integrally with the stage. Specifically, the position detection unit measures the main scanning direction position of the stage based on the measurement principle of a linear encoder system. Meanwhile, when the stage moves in the secondary scanning direction, the readhead moves in the secondary scanning direction by an amount corresponding to the stage's movement.

Therefore, when the linear scale, which moves integrally with the stage, moves in the secondary scanning direction, the readhead also moves in that direction. Therefore, by using the readhead after movement to read the scale, it can continue to detect the stage position. Thus, according to the present invention, even if the number of stage movements in the secondary scanning direction increases, there is no need to increase the number of readheads required, and a smaller number of readheads can be used to detect the stage position.

In addition, another aspect of the present invention is a drawing method, which moves a stage with a substrate carried on its upper surface, while alternately performing main scanning movements toward a main scanning direction and sub-scanning movements toward a sub-scanning direction intersecting the above-mentioned main scanning direction, and irradiates light from a drawing portion toward the above-mentioned substrate to perform drawing, wherein the above-mentioned main scanning direction and the above-mentioned sub-scanning direction are parallel to the above-mentioned upper surface and intersect with each other; wherein, a linear scale that is integrally provided with the above-mentioned stage and has a scale formed along the above-mentioned main scanning direction is read by a reading head to detect the relative position of the above-mentioned drawing portion and the above-mentioned stage in the above-mentioned main scanning direction, and when the above-mentioned stage moves toward the above-mentioned sub-scanning direction, the above-mentioned reading head is moved by an amount of movement corresponding to the amount of movement of the above-mentioned stage.

In this configuration, the present invention, based on the same principles as the aforementioned imaging device invention, can detect the position of the stage using a small number of read heads, even when the number of movements of the stage in the secondary scanning direction increases. (Compared to the effectiveness of the prior art)

As described above, according to the present invention, when a linear encoder consisting of a pair of linear scales and a read head is used to detect the position of the carrier, the read head also moves in the sub-scanning direction in response to the sub-scanning movement of the carrier. Therefore, even if the carrier moves frequently in the sub-scanning direction, position detection can be performed with a small number of read heads, thereby reducing the size and cost of the device.

The above-mentioned structure and other purposes and novel features of the present invention can be more clearly understood by referring to the accompanying drawings and reading the following detailed description. However, the drawings are for illustrative purposes only and are not intended to limit the scope of the present invention.

<First Embodiment> Figure 1 is a front view schematically illustrating the general configuration of an exposure apparatus, which is a first embodiment of the drawing apparatus of the present invention. Figure 2 is a block diagram illustrating an example of the electrical configuration of the exposure apparatus of Figure 1 . In Figure 1 and the following figures, the horizontal X direction, the horizontal Y direction orthogonal to the X direction, the vertical Z direction, and the rotational direction θ about a rotation axis parallel to the Z direction are appropriately indicated.

Exposure device 1 irradiates a substrate S (substrate to be exposed) with a layer of photosensitive material such as a resist with laser light in a predetermined pattern, thereby creating a pattern on the photosensitive material. Substrate S can be used for various substrates, such as semiconductor substrates, semiconductor package substrates, printed circuit boards, and glass substrates used in various display devices. Furthermore, its shape is not particularly limited; for example, a circular substrate, a rectangular substrate, or a substrate processed into a specific shape can be used as substrate S.

The exposure apparatus 1 includes a main body 11, which is composed of a main body frame 111 and a cover (not shown) attached to the main body frame 111. Various components of the exposure apparatus 1 are arranged inside and outside the main body 11.

The interior of the main body 11 of the exposure device 1 is divided into a processing area 112 and a handover area 113. In the processing area 112, there are mainly arranged a stage 2, a stage drive mechanism 3, an exposure unit 4, an alignment unit 5 and a position detection mechanism 8. These components are arranged on the base 100, or mounted on a gantry-shaped support frame 101, and the gantry-shaped support frame 101 is arranged on the base 100 in a manner that spans the base. In addition, an illumination unit 6 that supplies illumination light to the alignment unit 5 is arranged on the outside of the main body 11. In the handover area 113, a conveying device 7 such as a conveying robot that carries the substrate S in and out of the processing area 112 is arranged. In addition, a control unit 9 is arranged inside the main body 11. The control unit 9 is electrically connected to each component of the exposure device 1 to control the operation of each component.

The transport device 7, located in the transfer area 113 within the main body 11, receives unprocessed substrates S from an external transport device or substrate storage device (not shown) and loads them into the processing area 112. It also unloads (unloads) processed substrates S from the processing area 112 and discharges them to the outside. The loading of unprocessed substrates S and the unloading of processed substrates S are performed by the transport device 7 based on instructions from the control unit 9.

The carrier 2 has a flat plate-like shape and holds the substrate S placed on its upper surface in a horizontal position. A plurality of suction holes (not shown) are formed on the upper surface of the carrier 2. By applying negative pressure (suction pressure) to these suction holes, the substrate S placed on the carrier 2 is fixed to the upper surface of the carrier 2. The carrier 2 is driven by a carrier drive mechanism 3.

The stage drive mechanism 3 is an X-Y-Z-θ drive mechanism that moves the stage 2 in the Y direction (main scanning direction), X direction (sub-scanning direction), Z direction, and rotational direction θ (yaw direction). The stage drive mechanism 3 includes a Y-axis robot 31, a Y-moving stage 32, an X-axis robot 33, an X-moving stage 34, a θ-axis robot 35, and a Z-axis robot 37. The Y-axis robot 31 is a single-axis robot extending in the Y direction. The Y-moving stage 32 is driven in the Y direction by the Y-axis robot 31. The X-axis robot 33 is a single-axis robot extending in the X direction on the upper surface of the Y-moving stage 32. The X-moving stage 34 is driven in the X direction by the X-axis robot 33. The θ-axis robot 35 is driven along the rotation direction θ relative to the X-moving stage 34 , thereby driving the stage 2 supported on the upper surface of the X-moving stage 34 .

Therefore, the stage drive mechanism 3 can drive the stage 2 in the Y direction via the Y-axis servo motor of the Y-axis robot 31, in the X direction via the X-axis servo motor of the X-axis robot 33, and in the rotational direction θ via the θ-axis servo motor of the θ-axis robot 35. These servo motors are not shown in the figure. Furthermore, the stage drive mechanism 3 can drive the stage 2 in the Z direction via the Z-axis robot 37. The stage drive mechanism 3 moves the substrate S placed on the stage 2 by operating the Y-axis robot 31, X-axis robot 33, θ-axis robot 35, and Z-axis robot 37 in accordance with commands from the control unit 9.

To detect the position of the moving stage 2, a position detection mechanism 8 is provided. Specifically, the position detection mechanism 8 comprises a linear scale 81 extending along the Y direction on the upper surface of the stage 2, and a read head 82 mounted on the support frame 101 to read the scale (dimension) engraved on the linear scale 81. These constitute a linear encoder. The output of the read head 82 is input to the control unit 9.

The exposure unit 4 includes an exposure head 41 and a light irradiation unit 40. The exposure head 41 is positioned above the substrate S on the stage 2. The light irradiation unit 40, which includes a light source driver 42, a laser output unit 43, and an illumination optical system 44, irradiates the exposure head 41 with laser light. Multiple exposure units 4 can be provided at different positions in the X direction.

Laser light emitted from the laser emitting section 43 by the operation of the light source driver 42 is directed toward the exposure head 41 via the illumination optical system 44. The exposure head 41 modulates the laser light emitted from the light irradiation section 40 using a spatial light modulator 400 (hereinafter referred to as the "light modulator") and directs the light onto the substrate S positioned directly beneath it. In this manner, the laser beam exposes the substrate S, creating a pattern on the substrate S (exposure operation).

The alignment unit 5 includes an alignment camera 51 positioned above the substrate S on the stage 2. This camera 51 comprises a barrel, an objective lens, and a CCD image sensor, and captures images of alignment marks on the upper surface of the substrate S as it moves directly beneath it. The CCD image sensor in the alignment camera 51 is, for example, an area image sensor (two-dimensional image sensor).

The illumination unit 6 is connected to the lens barrel of the alignment camera 51 via an optical fiber 61 and supplies illumination light to the alignment camera 51. The illumination light, guided by the optical fiber 61 extending from the illumination unit 6, is directed through the lens barrel of the alignment camera 51 onto the upper surface of the substrate S. Light reflected from the substrate S passes through the objective lens and is incident on the CCD image sensor. This captures an image of the upper surface of the substrate S, producing an image. The alignment camera 51 is electrically connected to the control unit 9 and captures images based on instructions from the control unit 9, transmitting these images to the control unit 9.

The control unit 9 performs various processing operations by controlling the operations of the aforementioned units. To this end, the control unit 9 includes a CPU (Central Processing Unit) 91, memory (RAM) 92, storage 93, input unit 94, display unit 95, and interface unit 96. The CPU 91 reads and executes a control program 931 pre-stored in memory 93 to perform the various operations described below. Memory 92 is used for CPU 91's computational processing and for short-term storage of data generated as a result of computational processing. Memory 93 provides long-term storage for various data and the control program. Specifically, the memory 93 is a non-volatile memory device such as a flash memory device or a hard drive device. In addition to the control program 931 executed by the CPU 91, it also stores design data representing the content of the pattern to be drawn, such as CAD (Computer Aided Design) data 932.

The input unit 94 receives user input and, for this purpose, includes an appropriate input device such as a keyboard, mouse, or touch panel (not shown). The display unit 95 displays and outputs various information to inform the user and, for this purpose, includes an appropriate display device, such as a liquid crystal display panel. The interface unit 96 is responsible for communication with external devices. For example, the interface unit 96 functions when the exposure apparatus 1 receives control programs 931 and CAD data 932 from an external source. For this purpose, the interface unit 96 may also include a structure (such as a hard drive) and functionality for reading data from external storage media.

The CPU 91 executes a control program 931 to implement functional blocks such as the exposure data generator 911, exposure control unit 912, focus control unit 913, stage control unit 914, and position calculation unit 915 in software. Furthermore, at least a portion of each of these functional blocks may be implemented using dedicated hardware.

The exposure data generator 911 generates exposure data for modulating the light beam according to the pattern based on the CAD data 932 read from the memory 93. If the substrate S exhibits deformation, such as warping, the exposure data generator 911 corrects the exposure data based on the amount of warping, enabling drawing consistent with the shape of the substrate S. The exposure data is transmitted to the exposure head 41, which modulates the laser light emitted by the light irradiation unit 40 based on the exposure data. This modulated light beam, modulated according to the pattern, is then irradiated onto the substrate S, exposing a portion of the substrate S surface and drawing the pattern.

The exposure control unit 912 controls the light irradiation unit 40 to emit a laser beam having a predetermined power and spot size. The focus control unit 913 controls the projection optical system provided in the exposure head 41 to focus the laser beam on the surface of the substrate S.

The stage control unit 914 controls the stage drive mechanism 3 to achieve movement of the stage 2 for alignment adjustment and for scanning during exposure. During alignment adjustment, the position of the stage 2 is adjusted in the X, Y, Z, and θ directions so that the relative positional relationship between the substrate S placed on the stage 2 and the exposure head 41 at the start of exposure is a predetermined relationship. Meanwhile, during scanning during exposure, a main scanning motion is combined with a step feed in the X direction at a constant pitch (sub-scanning motion). The main scanning motion moves the stage 2 in the Y direction at a constant speed, allowing the substrate S to pass under the exposure head 41. The position calculation unit 915 calculates the position of the carrier 2 based on the signal output by the reading head 82 of the position detection mechanism 8 when reading the linear scale 81.

Figures 3A through 3C illustrate the main components of the exposure apparatus as viewed along the Y direction, and Figure 4 is a perspective view schematically showing the structure of the stage drive mechanism. Furthermore, Figures 3A through 3C correspond to side views of the exposure apparatus 1 as viewed along the (+Y) direction. However, to clearly illustrate the structure of the stage drive mechanism 3, the light irradiation unit 40, alignment unit 5, and control unit 9 have been omitted. Furthermore, in these and the following figures, dashed and dotted arrows shown near various components of the apparatus indicate the direction of movement of that component.

As shown in Figure 3A, a bracket-like support frame 101 is mounted on the base 100, spanning the stage drive mechanism 3 and the stage 2 supported by it in the X-direction. Mounted on this support frame 101 is the exposure head 41 of the exposure unit 4. While only one exposure head 41 is shown here as a representative example, the number of exposure heads 41 is not limited to this and can be any number. When multiple exposure heads 41 with identical structures are provided, they are spaced evenly in the X-direction. This allows for integrated relative movement of the substrate S during scanning.

The relative movement between the exposure head 41 and the substrate S is achieved by the stage drive mechanism 3 moving the stage 2. Specifically, the stage drive mechanism 3 alternately performs a main scanning motion and a sub-scanning motion. The main scanning motion continuously moves the stage 2 in the Y direction, while the sub-scanning motion advances the stage 2 a predetermined distance in the X direction. This allows the incident position of the exposure beam emitted from the exposure head 41 onto the substrate S to be varied, ultimately achieving exposure of the entire substrate S.

The position detection mechanism 8 is responsible for detecting the position of the stage 2 during these operations. Specifically, as shown in Figure 4, a linear scale 81 extending in the Y direction is mounted near the (+X) end of the upper surface of the stage 2. Linear scale 81 is formed, for example, from a glass plate and, as described later, is a two-dimensional linear scale with graduations (dimensions) printed at predetermined intervals in both the X and Y directions.

In the following description, the term "X-direction scale" refers to a scale with markings spaced at regular intervals along the X direction and used to detect position in the X direction. Similarly, the term "Y-direction scale" refers to a scale with markings spaced at regular intervals along the Y direction and used to detect position in the Y direction.

A reading head 82 is provided above the linear scale 81. The reading head 82 optically reads the scale of the linear scale 81 and outputs a signal corresponding to the reading result. As described later, the reading head 82 is a two-dimensional reading head that can separately read the X-direction scale and the Y-direction scale of the two-dimensional linear scale 81. The output signal from the reading head 82 is input to the position calculation unit 915 of the control unit 9. The position calculation unit 915 counts the signals output from the reading head 82 and calculates the position of the carrier 2. In addition, based on the change in the position, the movement speed and movement amount can be calculated.

The reading head 82 is mounted on the support frame 101 via a linear motion mechanism 83, which is movable in the X direction. The linear motion mechanism 83 moves the reading head 82 in the X direction within a predetermined range of motion based on control commands from the control unit 9. Examples of the linear motion mechanism include a linear motor, a ball screw mechanism, or a pinion and gear mechanism.

The reading head 82 is positioned in the X direction corresponding to the linear scale 81. The Y direction position of the reading head 82 remains fixed. Therefore, when the stage 2 moves in the Y direction (main scanning movement), the linear scale 81 passes directly below the reading head 82, and the reading head 82 sequentially reads the scale marks on the linear scale 81.

On the other hand, in response to the movement of the stage 2 in the X direction (sub-scanning movement), the linear motion mechanism 83 moves the reading head 82 in the X direction in conjunction with this movement. In this way, it can maintain the state in which the reading head 82 and the linear scale 81 face each other before and after the sub-scanning movement.

The following describes the setting of the movable range of the read head 82 with reference to Figures 3B and 3C. Figure 3B shows the position of the stage 2 when the laser light L emitted from the exposure head 41 is incident on the substrate S (+X) side end. Furthermore, Figure 3C shows the position of the stage 2 when the laser light L emitted from the exposure head 41 is incident on the substrate S (-X) side end.

Thus, the range of movement of stage 2 during sub-scanning is set so that exposure beam L illuminates the entire area encompassing both ends of substrate S in the X direction. Consequently, the movable range of read head 82 is also set so that it is aligned opposite linear scale 81 within the entire range of movement of stage 2. Specifically, the movable range is defined to encompass both the position directly above linear scale 81 when stage 2 is at its closest position in the (-X) direction within its range of movement, as shown in FIG3B ; and the position directly above linear scale 81 when stage 2 is at its closest position in the (+X) direction within its range of movement, as shown in FIG3C .

As shown in this example, in a configuration where only one exposure head 41 is provided, the travel distance of the stage 2 and the read head 82 is substantially equal to the length of the substrate S in the X direction. On the other hand, as will be described below, in a configuration where multiple exposure heads 41 are arranged in the X direction, each exposure head 41 only needs to expose a portion of the substrate S, so the required travel distance of the stage 2 and the read head 82 is reduced.

Figures 5A through 5C illustrate an example configuration using two exposure heads. As shown in Figure 5A , if the spacing P between the two exposure heads 41 is set to half the X-direction length Wx of the substrate S, each exposure head 41 only needs to expose half of the entire surface of the substrate S in the X-direction. Therefore, as shown in Figures 5B and 5C , the movement of the stage 2 and the read head 82 can be reduced compared to the example shown in Figures 3B and 3C . The greater the number of exposure heads 41, the smaller the movement of the stage 2 and the read head 82.

Furthermore, in recent years, as substrates S have become increasingly larger and patterns increasingly finer, the area that can be exposed in a single main scanning motion is a very small portion of the substrate S surface. Therefore, even if multiple exposure heads are provided, multiple sub-scanning motions, for example, dozens of steps, are required. The prior art described in Patent Document 2 requires multiple read heads to cover the entire motion range. In contrast, this embodiment, with a linear motion mechanism 83 that moves the read head 82 in the sub-scanning direction, eliminates the need for multiple read heads 82.

Figures 6A and 6B illustrate the position detection principle of the position detection mechanism. As described above, the position detection mechanism 8 of this embodiment detects the position of the stage 2 using a combination of a two-dimensional linear scale 81 and a read head 82 for reading the scale. Specifically, as shown in Figure 6A, the read head 82 includes three optical sensors 821, 822, and 823, each of which optically detects the scale. Meanwhile, the linear scale 81 includes X-direction scales Sx formed at regular intervals along the X direction, and Y-direction scales Sy formed at regular intervals along the Y direction.

Furthermore, for the purpose of illustrating the principle, a two-dimensional linear scale with this simple scale pattern is used as an example. However, various scale patterns other than this have been put to practical use as two-dimensional linear scales, and the embodiments of the present invention can also be appropriately selected from these. Furthermore, as for the resolution of the scale, a higher resolution is used than the accuracy required for stage position control in this device. For example, linear scales with nanometer-level resolution have been commercialized and can be appropriately applied to this embodiment.

One of the three optical sensors, optical sensor 823, is configured to read the Y-direction scale Sy. Meanwhile, the other two optical sensors, 821 and 822, are configured to read the X-direction scale Sx, and their positions are different in the Y-direction. In the following description, the optical sensor capable of reading the X-direction scale (e.g., optical sensors 821 and 822 in this example) is sometimes referred to as the "X-direction sensor," and the optical sensor capable of reading the Y-direction scale (e.g., optical sensor 823 in this example) is sometimes referred to as the "Y-direction sensor."

Furthermore, in the case where a single optical sensor can read two types of mutually orthogonal scales, such as a two-dimensional image sensor, the single optical sensor can also function as both an "X-direction sensor" and a "Y-direction sensor."

By combining the read head 82 and the two-dimensional linear scale 81 thus configured, the position detection mechanism 8 can detect the position of the stage 2 in the X and Y directions, as well as the rotation (deflection) of the stage 2 about the θ-axis, which is parallel to the Z axis. Specifically, the position of the stage 2 in the X direction can be detected based on the reading results of at least one of the optical sensors 821 and 822. Furthermore, the position of the stage 2 in the Y direction can be detected based on the reading results of the optical sensor 823. Furthermore, as described below, the deflection of the stage 2 can be determined by comparing the reading results of the optical sensors 821 and 822. These calculations are performed by the position calculation unit 915 of the control unit 9.

As shown in Figure 6B , consider a state where the X-direction scale Sx is tilted at an angle θ relative to the Y-direction, the direction in which the two X-direction sensors 821 and 822 are arranged. The X-direction position of stage 2 calculated based on the outputs of the two optical sensors 821 and 822 from the X-direction scale Sx differs from each other due to this tilt. Here, the symbols X1 and X2 represent the X-direction position of stage 2 calculated based on the outputs of optical sensors 821 and 822, respectively. Furthermore, the symbol d represents the Y-direction distance between the two optical sensors 821 and 822.

Thus, based on the relationship shown in Figure 6B, the following formula: θ = arctan{(X1 - X2) / d}… (Equation 1) The tilt θ, or deflection, can be calculated. Since the tilt θ is actually very small, the following approximate formula can be used: θ ≒ (X1 - X2) / d… (Equation 2)

Furthermore, if the stage 2, the object for position detection, and the reading head 82, the main body for detection, move simultaneously in the X direction, it is impossible to properly detect the movement of the stage 2 relative to the exposure head 41. To solve this problem, the exposure operation in this embodiment is configured as follows.

Figure 7 is a flow chart showing the processing details of the exposure operation in this embodiment. This processing is implemented by the CPU 91 of the control unit 9 executing the control program 931 stored in the memory 93. Furthermore, this processing begins with the substrate S, to be imaged, already placed on the stage 2 and having undergone predetermined alignment adjustments. However, since alignment adjustment techniques are well known, their description will be omitted here.

The stage 2, with the substrate S properly positioned, is positioned at a predetermined initial position by the stage drive mechanism 3 (step S101). Position detection then begins by the position detection mechanism 8 (step S102), and the stage drive mechanism 3 moves the stage 2 in the Y direction, beginning the main scan (step S103). While the stage 2 is moving, the position detection mechanism 8 constantly detects the stage's position, and the results are used to control the operations of the stage drive mechanism 3 and the exposure head 41.

When the stage 2 moves to the exposure start position, i.e., the position where the light beam L emitted from the exposure head 41 contacts one end of the substrate S (step S104), exposure of the substrate S by the exposure head 41 begins (step S105). At this point, based on the stage position detection results, the stage position is calibrated (in the X and θ directions) and the exposure head 41 (spatial light modulator 400) is controlled (in the Y direction) as needed.

When stage 2 moves in the Y direction and reaches the exposure end position (step S106), where exposure of one stripe is complete, it is determined whether exposure of the entire substrate S is complete (step S107). If exposure of the entire surface of substrate S is complete (YES in step S107), the process ends.

On the other hand, if unexposed areas remain on the substrate S (NO in step S107), exposure continues. Specifically, the stage 2 is moved in steps in the sub-scanning direction at a predetermined pitch (step S108). This causes the incident position of the exposure beam from the exposure head 41 to shift in the X direction. When the movement of the stage 2 in the sub-scanning direction is complete, the linear motion mechanism 83 then moves the read head 82 in the X direction based on the amount of stage 2 movement (step S109). The reason for this two-stage movement of the stage 2 and read head 82 at different times is as follows.

Figure 8 illustrates the movement of the stage 2 and the read head 82. Furthermore, in Figure 8 , to clarify the positional relationship between the sub-diagrams for easier understanding, one of the X-direction scales Sx is highlighted. However, this distinction is not necessarily made in an actual machine. In step S108, as indicated by arrow A in Figure 8 , while the read head 82 (more precisely, the X-direction sensors 821 and 822) is fixed, the stage 2 moves only in the X-direction, for example, the (+X) direction. During this period, the X-direction sensors 821 and 822 operate, detecting the amount of movement of the stage 2 in the X-direction. The detected movement M1 represents the movement of the stage 2 relative to the exposure head 41 fixed to the support frame 101 and serves as information used to control the exposure operation.

Meanwhile, in step S109, while stage 2 is stopped, only the reading head 82 moves in the (+X) direction. However, for ease of explanation, in FIG8 , as indicated by arrow B, stage 2 moves in the (-X) direction relative to the reading head 82. During this period, the movement of the reading head 82 is also used to determine the movement amount M2 of the reading head 82 relative to the stage 2.

In a configuration where multiple read heads are pre-positioned to correspond to the sub-scanning movement of the stage, since the position of each read head is fixed at the same movement pitch, there is no need to consider positional offset relative to the stage. In contrast, in this embodiment, the movement of the read head 82 itself is utilized, resulting in a more complex situation through relative movement with the stage 2. Specifically, for example, positional offset may occur between the stage 2 and the read head 82. As described above, by moving the two at different times and pre-detecting the amount of movement between them, the amount of movement between the stage 2 and the exposure head 41, and the amount of movement between the stage 2 and the read head 82, can be independently detected.

This eliminates the aforementioned positional offset problem. Specifically, the difference between the movement amount M1 of the stage 2 detected when the read head 82 is fixed and the movement amount M2 of the read head 82 detected when the stage 2 is fixed represents the relative movement amount of the read head 82 relative to the stage 2, or the aforementioned "positional offset," ΔM. The stage position detected after the Nth (N is a natural number) subscan movement (e.g., arrow A in Figure 8 ) includes the aforementioned positional offset caused by the movement of the read head 82. For example, the movement amount M3 of the carrier 2 calculated based on the detection result of the reading head 82 in the (N+1)th sub-scanning movement (for example, arrow C in Figure 8) includes the above-mentioned position offset generated when the reading head 82 moves between the Nth carrier movement and the (N+1)th carrier movement.

Therefore, the original movement amount M4 of stage 2 during the (N+1)th sub-scanning movement can be accurately calculated by adding or subtracting the offset ΔM corresponding to the magnitude of the positional offset from the movement amount M3 determined based on the detection results of the reading head 82. The positional offset relative to stage 2 is accumulated each time the reading head 82 moves. Thus, when calculating the stage position based on the initial position, for example, the stage position can be accurately calculated by accumulating the positional offset for each movement and correcting the stage movement amount from the initial position based on this accumulated value.

The hardware configuration required to enable this process is to be able to read the linear scale 81 without moving the read head 82 before and after a single sub-scan of the stage 2. This requirement can be met by appropriately setting the read range (field of view) of the read head 82, the X-direction dimension of the linear scale 81, and the position of the read head 82 relative to the linear scale 81.

When the reading head 82 moves in the X direction, its position in the Y direction may also shift slightly. To address this issue, when the reading head 82 moves, not only the X-direction positional offset is detected, but also the Y-direction positional offset is detected using the reading results from the Y-direction scale Sy. This information can be used to make appropriate corrections. Furthermore, by determining positional offsets in both the X and Y directions, offsets along the θ axis, or in the tilt direction, can also be determined. Using these results, the tilt (deflection) of the stage 2 can be similarly corrected.

As described above, in the exposure apparatus 1 of this embodiment, the position of the stage 2 during the main and sub-scanning movements is detected by the position detection mechanism 8. This position detection mechanism 8 utilizes the measurement principle of a linear encoder composed of a linear scale 81 and a reading head 82. The linear scale 81 extends in the main scanning direction, i.e., the Y direction, and can continuously detect the position of the stage 2 during the main scanning movement.

On the other hand, in the secondary scanning direction, or the X direction, the reading head 82 is moved in accordance with the stepping movement of the stage 2 (linear scale 81), and the reading head 82 can read the scale at various positions in the secondary scanning direction. This eliminates the need for multiple reading heads in the secondary scanning direction, thus reducing the resulting increase in device size and cost.

The linear scale 81 is a two-dimensional scale. To read the scale in the X and Y directions, the readout head 82 is equipped with a plurality of optical sensors 821-823. Based on these readings, the position detection mechanism 8 detects the position of the stage 2 in the X and Y directions, as well as its posture in the θ direction (yaw direction).

The movement of the reading head 82 is performed exclusively at different times from the movement of the stage 2, meaning that their movements do not overlap in time. Specifically, the stage 2 moves while the reading head 82 is stationary, and the reading head 82 detects its movement relative to the stage 2. The reading head 82 then moves while the stage 2 is stationary, during which time the reading head 82 detects its movement relative to the stage 2. Furthermore, although the stage 2 is first moved in the secondary scanning mode, followed by the movement of the reading head 82, this order can also be reversed.

This prevents the following problems: the adverse effects caused by the movement of the read head 82, namely, a decrease in measurement accuracy due to the change in the position of the read head 82, the main measurement object, between the exposure head 41 and the stage 2. From another perspective, even if the linear motion mechanism 83's positioning accuracy for the read head 82 is not very high, any resulting positional deviation can be detected and corrected, thus not affecting the measurement accuracy of the stage 2's position relative to the exposure head 41. Because a high-precision linear motion mechanism 83 is not required, the resulting cost increase can be minimized.

<Second Embodiment> Figures 9A to 9C and 10 schematically illustrate the main configuration of an exposure apparatus 1A, a second embodiment of the drawing apparatus of the present invention. More specifically, Figures 9A to 9C show the main components of the exposure apparatus 1A of the second embodiment as viewed along the Y direction, and Figure 10 is a perspective view schematically illustrating the stage drive mechanism 3 and surrounding components. While the position detection mechanism of the exposure apparatus of this embodiment differs from that of the first embodiment, the remaining configuration and basic operation are the same as those of the first embodiment. Therefore, components identical to those of the first embodiment are designated by the same reference numerals, and detailed descriptions are omitted.

As shown in Figures 9A and 10 , the position detection mechanism 8A of the exposure apparatus 1A of this embodiment includes two linear scales 851 and 852 mounted on the stage 2; two reading heads 861 and 862; a movable member 87 integrally supporting the reading heads; and a linear motion mechanism 88 that moves the movable member 87 in the X direction. One linear scale 851 is located near the end of the stage 2 on the (-X) side, and the other linear scale 852 is located near the end of the stage 2 on the (+X) side. Both linear scales extend in the Y direction.

The two reading heads 861 and 862 are positioned at different positions in the X direction and are mounted below a movable member 87 extending in the X direction, at a pitch equal to or substantially equal to the pitch of the linear scales 851 and 852 on the stage 2. A linear motion mechanism 88 moves the movable member 87 in the X direction in response to control commands from the control unit 9. This allows the two reading heads 861 and 862 to move integrally in the X direction.

Furthermore, as with the read heads 82 of the first embodiment, two read heads, each supported by an independent linear motion mechanism, may be provided. Furthermore, in this embodiment, the number of exposure heads 41 can be any number. By deploying multiple exposure heads 41, the range of motion of the sub-scanning movement of the stage 2 can be reduced. In this case, the position detection mechanism 8A is also independent of the number of exposure heads 41 deployed; it is sufficient to provide two sets of linear scales and read heads corresponding to the opposite ends of the stage 2. By reducing the range of motion of the stage 2, the range of motion of each read head can also be reduced, similar to the above-mentioned embodiment.

The reading head 861 reads the scale of the linear scale 851. On the other hand, the reading head 862 reads the scale of the linear scale 852. That is, in this embodiment, linear encoders are provided at both ends of the stage 2 in the X direction.

With this configuration, linear encoders are used to detect the position of stage 2 at both ends in the X direction. The exposure operation, including the position detection principle and processing, is fundamentally the same as that of the first embodiment. That is, in this embodiment, exposure can also be achieved by executing the processing shown in Figure 7.

In this case, if the Y-direction position of stage 2 obtained from the readings at both ends differs from each other, it is considered that stage 2 is tilted in the θ direction. In other words, when the Y-direction position is detected at both ends of the stage, the θ-direction tilt of stage 2 can be detected even without using the X-direction position detection results.

Compared to the first embodiment shown in FIG6B , the second embodiment allows for a larger distance between the two optical sensors used for comparison to detect the tilt of the stage 2 in the θ direction. Therefore, the second embodiment achieves superior tilt detection accuracy compared to the first embodiment.

Therefore, if read heads 861 and 862 can each read the Y-direction scale, the Y-direction position and tilt around the θ-axis of stage 2 can be detected. In this sense, at least one of read heads 861 and 862 need not be capable of reading the X-direction scale. Furthermore, the corresponding linear scales 851 and 852 do not necessarily need to be two-dimensional; a Y-direction scale is sufficient.

On the other hand, a two-dimensional linear scale is still useful for detecting the X-direction position of stage 2. Therefore, for example, one of linear scales 851 and 852 can be configured as a one-dimensional scale, and the other as a two-dimensional scale. In this case, for the linear scale corresponding to one of read heads 861 and 862, a read head configured only to read the Y-direction position can be used.

Furthermore, in the first embodiment, the read head 82 is equipped with two optical sensors 821 and 822 for reading the X-direction scale, in order to detect not only the X-direction position but also the attitude of the stage 2 about the θ-axis. However, in this embodiment, since the attitude of the stage 2 can be determined by comparing the Y-direction position detection results at the two ends of the stage 2, only one optical sensor is required for reading the X-direction scale.

Therefore, as the configuration of the position detection mechanism 8A, both of the following are true: (1) Both linear scales 851 and 852 are two-dimensional scales; (2) One of the linear scales 851 and 852 is a two-dimensional scale, and the other is a one-dimensional (Y direction) scale.

Furthermore, for the two reading heads 861 and 862 whose linear scales are opposed to each other and are two-dimensional, both of the following are true: (A) A configuration with two X-direction sensors and one Y-direction sensor, as shown in Figure 6A; (B) A configuration with one X-direction sensor and one Y-direction sensor. Furthermore, for the reading heads whose linear scales are opposed to each other and are one-dimensional, at least one Y-direction sensor is sufficient.

As a practical problem, various structures formed by appropriately combining the above structures can be considered. Even by using any one of the structures, the X-direction and Y-direction positions of the stage 2 relative to the exposure head 41 (or a fixed position reference that replaces it) and the tilt around the θ-axis can be detected at any time and with high precision during the execution of the main scanning movement and the sub-scanning movement.

Furthermore, if, for example, a high-precision linear motion mechanism 88 is used, the positioning accuracy of the read heads 861 and 862 during movement in the X direction is sufficiently high and reproducible, then positional deviation caused by the movement of the read heads 861 and 862 will not be a problem. In this case, the two linear scales 851 and 852 can each be configured as a one-dimensional (Y-direction) scale, with the read heads 861 and 862 also having only Y-direction sensors. In this configuration, at least the Y-direction position and the θ-direction tilt of the stage 2 can be detected with the same accuracy as in the above-described embodiment.

<Other> As described above, in each of the above embodiments, exposure apparatuses 1 and 1A correspond to one aspect of the "drawing apparatus" of the present invention. Furthermore, substrate S corresponds to the "substrate" of the present invention, and stage 2 corresponds to the "stage" of the present invention. Furthermore, exposure unit 4, particularly exposure head 41, functions as the "drawing section" of the present invention. Furthermore, stage drive mechanism 3 functions as the "first moving mechanism" of the present invention.

In addition, the linear scales 81, 851, and 852 are equivalent to the "linear scales" of the present invention, the reading heads 82, 861, and 862 are equivalent to the "reading heads" of the present invention, and the linear motion mechanisms 83 and 88 are equivalent to the "second moving mechanism" of the present invention. The position detection mechanism 8, 8A and the position calculation unit 915 having these mechanisms are integrated and function as the "position detection unit" of the present invention.

Furthermore, the present invention is not limited to the above-described embodiment and various modifications other than those described above are possible without departing from the scope of the present invention. For example, in the above-described embodiment, a linear scale may be mounted on one or both ends of the flat upper surface of the carrier 2 in the X direction. However, the linear scale only needs to be configured to move integrally with the carrier. More preferably, the linear scale only needs to be configured so that their relative positional relationship remains unchanged, and does not need to be directly mounted on the carrier. For example, a configuration in which the carrier and the linear scale are separately mounted relative to a common base member is also possible.

Furthermore, for example, in the position detection mechanisms 8 and 8A of the above-described embodiments, the reading heads 82, 861, and 862 are mounted on a bracket-like support frame 101 that spans the stage 2. Consequently, the distance between the reading heads and the linear scales 81, 851, and 852 is relatively large. However, the arrangement of the reading heads is not limited to this; as long as the reading heads are supported independently of the movement of the stage 2 and do not interfere with such movement at a position where they can read the linear scale, they will suffice.

Furthermore, any form of utilization of the information regarding the position and posture of the stage 2 detected by the position detection mechanisms 8 and 8A is possible. While the above embodiments describe the use of information for controlling the exposure head 41 or the stage drive mechanism 3, other uses, for example, can be made for abnormality detection based on position detection results.

Furthermore, in the second embodiment, the linear scales are disposed at both ends in the X direction of the stage 2. However, the two linear scales only need to be disposed at different positions in the X direction, and may be disposed at two locations on one side of the stage, for example.

Furthermore, in the above-described embodiment, the position of stage 2 in the X and Y directions is detected by reading a linear scale provided at the X-direction end of stage 2. However, in the present invention, it is sufficient that the linear scale can at least "detect the position of the stage in the main scanning direction using the principle of a linear encoder." Therefore, other means can be used for position detection in the X direction. For example, a linear scale extending in the X direction (sub-scanning direction) can be provided on the stage, and position detection in the X direction can be performed by reading this linear scale.

Furthermore, as a specific example of the "drawing device" of the present invention, the exposure devices 1 and 1A of the above-described embodiments use a light beam modulated according to drawing data to expose the surface of a substrate having a photosensitive layer formed thereon, thereby drawing a pattern. However, the drawing method is not limited to this method and can be any method, such as drawing by exposing through a photomask or a mask, or by directly processing the substrate surface with laser light.

Furthermore, the exposure apparatuses 1 and 1A of the above-described embodiments are configured with a step-and-scan stage drive mechanism that alternately performs continuous stage movement in the main scanning direction and step movement in the sub-scanning direction. However, the present invention is also applicable to other types of imaging apparatuses, for example, that sequentially scan each predetermined two-dimensional region while changing position, i.e., a step-and-repeat type of movement, in which the stage drive mechanism employs a stage drive mechanism that alternately performs continuous stage movement in the main scanning direction and step movement in the sub-scanning direction.

While specific embodiments have been described above, the linear scale in the position detection unit of the imager of the present invention may also be a two-dimensional linear scale with graduations in both the main and sub-scanning directions. This configuration allows the position of the stage to be detected independently in both the main and sub-scanning directions. Furthermore, with this configuration, the position detection unit can detect the deflection of the stage based on the reading results of the read head, in addition to detecting the position of the stage in both the main and sub-scanning directions.

Alternatively, for example, the position detection unit may include multiple linear scales positioned at different locations in the secondary scanning direction, and multiple read heads corresponding to each of the multiple linear scales. With this configuration, the tilt of the stage can be detected based on the positional offsets calculated from the reading results of each of the multiple read heads. In other words, this configuration allows the position detection unit to detect the extent of the stage's deflection in addition to detecting the position of the stage in the primary scanning direction.

In this case, at least one of the multiple linear scales can be a two-dimensional linear scale with graduations in both the main and sub-scanning directions. This configuration allows independent detection of the stage position in both the main and sub-scanning directions. This allows detection of the stage position and the extent of stage deflection in both the main and sub-scanning directions.

Furthermore, the drawing device and drawing method of the present invention can be configured so that the period during which the stage moves in the secondary scanning direction does not overlap with the period during which the read head moves, that is, the two movements occur exclusively at different times. With this configuration, the stage moves while the read head is stationary, and only the amount of stage movement can be determined based on the linear scale reading results at that time. On the other hand, the amount of movement of the read head relative to the stage can be determined based on the linear scale reading results when the stage is stationary. Using this information, it is possible to proactively prevent a potential decrease in detection accuracy caused by read head movement, which should serve as the measurement benchmark.

The present invention has been described above based on specific embodiments, but this description is not intended to be construed in a limiting sense. Anyone skilled in the art will readily understand various modifications of the disclosed embodiments by referring to this description, as well as other embodiments of the present invention. Therefore, the accompanying patent claims are intended to include such modifications or embodiments as long as they do not depart from the actual scope of the present invention. (Industrial Applicability)

The present invention is applicable to the field of technology for forming patterns on substrates such as semiconductor substrates, semiconductor package substrates, printed circuit wiring substrates, or glass substrates to draw patterns on the substrates.

1.1A: Exposure device (tracing device) 2: Stage 3: Stage drive mechanism (first moving mechanism) 4: Exposure unit 5: Alignment unit 6: Illumination unit 7: Transport device 8,8A: Position detection mechanism (position detection unit) 9: Control unit 11: Main unit 31: Y-axis robot 32: Y-transfer stage 33: X-axis robot 34: X-transfer stage 35: θ-axis robot 37: Z-axis robot 40: Light irradiation unit 41: Exposure head (tracing unit) 42: Light source drive unit 43: Laser output unit 44: Illumination optical system 51: Alignment camera 61: Optical fiber 81, 851, 852: Linear scale 82, 861, 862: Reading head 83, 88: Linear motion mechanism (second moving mechanism) 91: CPU 92: Memory 93: Storage 94: Input unit 95: Display unit 96: Interface unit 100: Base unit 101: Support frame 111: Main body frame 112: Processing area 113: Interface area 400: Spatial light modulator 821, 822: X-direction sensor (optical sensor) 823: Y-direction sensor (optical sensor) 911: Exposure data generation unit 912: Exposure control unit 913: Focus control unit 914: Stage control unit 915: Position calculation unit (position detection unit) 931: Control program 932: CAD data L: Exposure beam (laser beam, light beam) S: Substrate Sx: X-axis scale Sy: Y-axis scale X: Sub-scanning direction Y: Main scanning direction Z: Vertical axis θ: Rotational direction

Figure 1 is a front view schematically showing a first embodiment of the drawing device of the present invention. Figure 2 is a block diagram showing an example of the electrical configuration of the exposure device of Figure 1. Figure 3A is a diagram showing the main components of the exposure device as viewed along the Y direction. Figure 3B is a diagram showing the main components of the exposure device as viewed along the Y direction. Figure 3C is a diagram showing the main components of the exposure device as viewed along the Y direction. Figure 4 is a perspective view schematically showing the configuration of the stage drive mechanism. Figure 5A is a diagram showing an example configuration with two exposure heads. Figure 5B is a diagram showing an example configuration with two exposure heads. Figure 5C is a diagram showing an example configuration with two exposure heads. Figure 6A is a diagram illustrating the position detection principle of the position detection mechanism. Figure 6B is a diagram illustrating the position detection principle of the position detection mechanism. Figure 7 is a flowchart showing the exposure process in this embodiment. Figure 8 is a diagram showing the movement of the stage and read head. Figure 9A is a diagram showing the main components of the exposure apparatus of the second embodiment as viewed along the Y direction. Figure 9B is a diagram showing the main components of the exposure apparatus of the second embodiment as viewed along the Y direction. Figure 9C is a diagram showing the main components of the exposure apparatus of the second embodiment as viewed along the Y direction. Figure 10 is a perspective view schematically showing the stage drive mechanism and surrounding components.

2: Carrier

3: Carrier drive mechanism (first moving mechanism)

8: Position detection mechanism (position detection unit)

31: Y-axis robot

32:Y mobile station

33: X-axis robot

34:X moving platform

35: θ-axis robot

37: Z-axis robot

41: Exposure head (drawing unit)

81: Linear ruler

82: Read Header

83: Direct action mechanism (second moving mechanism)

100: Base

101: Support Frame

L: Exposure beam (laser light, light beam)

S:Substrate

X: Secondary scanning direction

Y: Main scanning direction

Z: Vertical direction

Claims (8)

A drawing device comprises: a stage capable of placing a substrate on an upper surface; a drawing unit configured to draw the substrate placed on the stage by irradiating light; a first moving mechanism configured to move the stage relative to the drawing unit, performing a main scanning movement in a main scanning direction and a secondary scanning movement in a secondary scanning direction intersecting the main scanning direction, wherein the main scanning direction and the secondary scanning direction are parallel to the upper surface and intersect with each other; a position detecting unit configured to detect the relative position of the drawing unit and the stage in the main scanning direction; the position detecting unit comprising: a linear scale integrally provided with the stage and having graduations formed along the main scanning direction; a reading head configured to read the graduations; and A second movement mechanism moves the reading head relative to the drawing unit in the secondary scanning direction. When the stage moves in the secondary scanning direction by the first movement mechanism, the second movement mechanism moves the reading head by an amount corresponding to the movement of the stage. The period during which the stage moves in the secondary scanning direction by the first movement mechanism and the period during which the reading head moves by the second movement mechanism do not overlap. The drawing device of claim 1, wherein: The linear scale is a two-dimensional linear scale having graduations in the main scanning direction and the secondary scanning direction. The drawing device of claim 2, wherein: The position detection unit detects the position of the stage in the main scanning direction and the sub-scanning direction, and the deflection of the stage, based on the reading result of the reading head. The imaging device of claim 1, wherein: the position detection unit includes a plurality of linear scales disposed at different positions in the secondary scanning direction, and a plurality of reading heads disposed corresponding to each of the plurality of linear scales. The drawing device of claim 4, wherein the position detection unit detects the position of the stage in the main scanning direction and the deflection of the stage based on the reading results of each of the plurality of reading heads. The drawing device of claim 4, wherein: At least one of the plurality of linear scales is a two-dimensional linear scale having graduations in the main scanning direction and the secondary scanning direction. The drawing device of claim 6, wherein the position detection unit detects the position of the stage in the main scanning direction and the sub-scanning direction, and the deflection of the stage, based on the reading results of the plurality of reading heads. A drawing method is provided, wherein a stage having a substrate mounted on its upper surface is moved, alternating between a main scanning direction and a secondary scanning direction intersecting the main scanning direction, while irradiating light from a drawing portion toward the substrate to perform drawing. The main scanning direction and the secondary scanning direction are parallel to and intersecting the upper surface. The method comprises: detecting the relative position of the drawing portion and the stage in the main scanning direction by reading a linear scale integrally provided with the stage and having graduations formed along the main scanning direction with a reading head. When the stage moves in the secondary scanning direction, the reading head is moved by an amount corresponding to the amount of movement of the stage. The period during which the stage moves in the secondary scanning direction and the period during which the reading head moves do not overlap.