JP2815762B2 - Method of aligning film and reticle in film exposure apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for aligning a film and a reticle in an exposure apparatus for sequentially exposing a wiring pattern to each frame of a long film coated with a photosensitive resist. .

[0002]

2. Description of the Related Art Conventionally, in a camera or a calculator, a packaged IC or a resistor is soldered on a plate-shaped printed circuit board. With this method, the size of the camera and calculator itself becomes large, and it is not possible to respond to the demand for performance improvement,
Recently, it has been bonded to a film-like printed circuit board.
In this case, it is necessary to apply a wiring pattern on a film-shaped printed circuit board. Usually, a long film coated with a photosensitive resist is conveyed, and one frame at a time,
The wiring pattern drawn on the reticle is projected and exposed.

However, when the wiring pattern is not exposed at an accurate position, if an element such as an IC is bonded, mounting errors will occur. For this reason, the transported film 1
It is necessary to make the exposure position of the frame and the projected image of the wiring pattern accurate. This accuracy is said to be within ± 10 μm.

Japanese Patent Application Laid-Open No. Hei 1-298362 discloses such a technique. In this publication, a reference mark for alignment is provided on the reticle, and a hole for reference alignment is provided for each frame of the film (in this case, one of the perforations is also used).
Is provided. Then, the position of the center of gravity of the projected image of the alignment mark and the position of the center of gravity of the alignment hole are obtained by an image pickup device composed of a CCD, and the position of the film is moved so that these coincide.

[0005]

However, when a CCD area sensor having a large number of pixels is used as an image pickup device, there is a problem that the position of the center of gravity is detected very slowly. Also, CC
The image detection by D recognizes an image based on the amount of received light in each pixel. That is, although depending on the size of one pixel, the position of the image cannot be detected with an accuracy smaller than the light receiving area of the pixel. Therefore, a problem to be solved by the present invention is to quickly detect the positional relationship between a conveyed film and a reticle. Next, the position control of the film and the reticle is to be detected with an accuracy smaller than the light receiving area of one pixel constituting the CCD.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a method of aligning a film and a reticle in a film exposure apparatus according to the present invention uses a method in which a plurality of frames arranged on a belt-like film are sequentially moved to an exposure position. In a method of aligning a film and a reticle in a film exposure apparatus in which a wiring pattern on a reticle is exposed through a projection lens to a wiring pattern on a reticle by light from an irradiation unit, a band-shaped film has one frame each. At least 2
One or more film-side alignment marks are formed, and a reticle-side alignment mark is formed on the reticle corresponding to each of the film-side alignment marks, along with the wiring pattern projected and transferred to the film, and the film is transported to the exposure position Then, the projected images of the film side alignment mark and the reticle side alignment mark are projected on the CCD line sensor, and the light amount detected by each pixel constituting the CCD line sensor is compared with a preset reference value. The position of the projected image of the film-side alignment mark and the reticle-side alignment mark is determined for each pixel, the data is input to the system controller, and the reference value is changed. Repeat, then the system controller The signals, and wherein the moving the reticle in the correct position.

[0007]

Since the CCD line sensor is used as the means for detecting the projected image of the alignment mark, the detection speed is faster than when an area sensor is used. In addition, when detecting the projection image at each pixel, the reference value to be compared with the amount of light received at each pixel is changed, so that positioning can be performed with an accuracy smaller than the detectable area of the pixel.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is an explanatory view of a film exposure apparatus according to the present invention. In this apparatus, a wiring pattern of a reticle R is sequentially exposed on a long film F along its length direction. (In the figure, the wiring pattern is denoted by A for convenience.) The irradiation unit 10 has a built-in lamp 11 such as an ultra-high pressure mercury lamp, which efficiently emits light whose resist has sensitivity. And the lamp 11
In addition, an elliptical converging mirror, a reflecting mirror, or a lamp 11
It has shutters and various types of lenses that block light emitted from the camera.

The irradiating unit 10 emits light having an alignment wavelength when aligning a film and a reticle by means of switching between light having an exposure wavelength at which the resist has sensitivity and light having an alignment wavelength at which the resist has no sensitivity. Then, when exposing the wiring pattern, light having an exposure wavelength can be irradiated. As the switching means, for example, a sharp cut filter can be used. Further, the light from the lamp 11 may be extracted by a glass fiber or the like, and the alignment mark and the vicinity thereof may be illuminated so as to avoid a region to be exposed.

The reticle R is disposed at a position where light from the irradiation unit 10 is irradiated. The reticle R has a wiring pattern RP to be projected onto the film F as shown in FIG. 2 and an alignment on the reticle side corresponding to each of film-side alignment marks FM (hereinafter referred to as film-side marks) FM to be described later. A mark (hereinafter, referred to as a reticle-side mark) RM is formed. The reticle-side mark RM is formed as a circular opaque portion in a rectangular transparent area.

As shown in FIG. 3, a long film F
Two film side marks FM are formed for each frame F10 of the film F. In this example, the film-side mark FM is formed by a square hole, and a projection image RM 'of the reticle-side mark is projected within this range. The film-side mark FM is not limited to a hole, and may be a light-transmitting portion.

Reference numeral R10 denotes a reticle position adjusting mechanism, which comprises a reticle holder R11 and a servo motor R12. When the servo motor R12 is driven by a signal from a system controller described later, the reticle holder R11 moves, and the reticle R also moves. The reticle holder R11 can adjust the position of the reticle R in two directions (X direction and Y direction) perpendicular to each other in a plane perpendicular to the optical axis.
Adjustment to rotate the reticle R about the optical axis (Θ
Adjustment). Therefore, reticle holder R1
Actually, three servo motors R12 for driving the motor 1 are provided so that each of the servomotors R, X, and Y can be driven.

The projection lens 20 is provided with the illuminated reticle R
Is projected. The projection lens 20 has a resolution of, for example, an exposure line width of about 5 μm.
The stage 30 is provided with a vacuum suction mechanism (not shown) that blows air when the film F is fed stepwise and vacuum sucks the film during exposure.
The stage 30 has a detection unit 40. This detector 40
Has an objective lens 42 in a lens case 41 as shown in FIG. The objective lens 42 is provided in two sets of two each for taking chromatic aberration and spherical aberration. Also,
Filters can also solve the problem of chromatic aberration. The light emitted from the lens case 41 is transmitted to the half mirror 4
3, the CCD partially passes through the neutral density filter 44
It is input to the monochrome camera 45. This CCD monochrome camera 4
Although not shown, the signal input to 5 is monitored. That is, the projection state of the projection image RM ′ of the reticle side mark on the film side mark FM can be visually confirmed. On the other hand, the light that is not refracted by the half mirror 43 passes through the H-line G-line cut filter 46 and the neutral density
Similarly reaches the half mirror 48. The half mirror 48 partially controls the line sensor 4 in the feed direction.
9a, and a part is input to the line sensor 49b in the width direction. Hereinafter, the line sensor 49 is referred to as the line sensor 49 together with the line sensor 49b. An output signal from the line sensor 49 is transmitted to the system controller 5.
Sent to 0.

When the motor 52 is driven by a signal from the system controller 50, the feed roller 51 rotates. Thereby, the film F is transported. Reference numeral 53 denotes a press roller for pressing the film between the feed roller 51 and the feed roller 51. Reference numeral 54 denotes a driven roller. Reference numeral 55 denotes a reel for winding up the film F, and reference numeral 56 denotes a reel for unwinding. Further, reference numeral 57 denotes a spacer reel which winds and unwinds the spacer film. Reference numeral 58 denotes a sensor for detecting the amount of film slack. By the operation of the plurality of rollers, one frame F10 of the film F can be favorably stepped to the position where the image is projected by the projection lens 20.

When a drive start signal is sent from the system controller 50 to the motor 52,
Rotates to transport the film F. When the film side mark FM is conveyed to within the detection range of the detector 40, the motor 52 stops. This stop is performed by the feed roller 5
One rotation can be measured by an encoder. In this state, it is roughly aligned. And
From here, accurate positioning within ± 10 μm is performed.
The rough alignment method is not limited to this method. For example, first, the film F is transported at a relatively high speed, and then the film F is switched to a slowed down speed while irradiating the alignment wavelength light. , Detector 4
There is also a method of stopping conveyance when 0 detects the film side mark FM.

Next, an accurate positioning method will be described. FIG. 5A shows a projected image RM ′ of the reticle-side mark projected on the film-side mark FM and the position of the line sensor 49 for convenience. FIG. 5B is a diagram showing the line sensor 49 corresponding to FIG. FIG. 5C is a diagram illustrating a state in which each pixel forming the line sensor 49 receives light having an alignment wavelength. Here, the line sensor 49 is, for example,
There are 1024 pixels having a size of 14 × 200 μ.
In the figure, the number of pixels is reduced for explanation. And
On the film side mark FM, since the size is enlarged by the objective lens 42, the size becomes, for example, 2.5 times. The light of the alignment wavelength does not pass through the round opaque portion of the reticle-side mark RM, but passes through other portions. Then, the transmitted light enters the detection unit 40,
The light is received by the line sensor 49 via the optical system described above. Since the line sensor 49 is composed of a large number of pixels, the position of the image RM ′ of the reticle-side mark on the film-side mark FM can be known by detecting at which pixel the light is received. Hereinafter, this will be described.

FIG. 5B shows that the pixel group a and the pixel group c of the line sensor 49 receive light of the alignment wavelength, and the pixel group b does not receive light. The pixels d at both ends are provided outside the area of the film-side mark FM, and this portion does not receive light. FIG. 5 (c)
In the graph, the vertical axis indicates whether or not each pixel is receiving light of the alignment wavelength by H / L, and the horizontal axis indicates the position of the pixel. In the determination of H / L, the amount of received light in each pixel is compared with a reference value, and if the amount is larger than the reference value, the light receiving state is set to H. On the other hand, when the amount of received light is smaller than the reference value, the pixel is set to L because light is not received at that pixel. Then, the result of each pixel is transmitted to the system controller 50. For this reason, when there is a portion that receives the light of the alignment wavelength and a portion that does not receive the light of the alignment wavelength within the range of one pixel (that is, the transparency of the projected image RM ′ of the reticle side mark in one pixel) If there is a boundary between the part and the opaque part), it is determined which of H / L by comparing with a reference value and transmitted.

The system controller 50 detects an intermediate position e1 from one end a1 of the pixel group a determined to be receiving light and one end c2 of the pixel group c also determined to be receiving light. Is recognized as the center position of the film side mark FM. On the other hand, an intermediate position is obtained from the other end a2 of the pixel group a determined to be receiving light and the other end c1 of the pixel group c also determined to be receiving light, so that the image RM ′ of the reticle side mark is obtained. The intermediate position e2 can be recognized. In this manner, by determining the center positions of the center of the film side mark FM and the image RM 'of the reticle side mark, the shift amount can be grasped. As described above, the positional information of the film in the feed direction and the width direction can be obtained. Since there are two film side marks FM in the width direction of the film F, two pieces of information are recognized by the system controller. For example, when the film F is meandering and conveyed, different information is transmitted in two directions.

Next, the reference value will be described. FIG.
(A) is an enlarged view of one pixel. In the figure, the hatched portion indicates the region receiving the light of the alignment wavelength in the pixel region, and the portion without the hatched portion indicates the non-receiving region, that is, the opaque portion of the image RM ′ of the reticle side mark. . M indicates the short width of one pixel, for example, 14 μm. FIG. 6C shows the amount of light received by the pixel shown in FIG. P indicates a reference value. In this case, the amount of light received at the alignment wavelength is
Since the value exceeds the reference value P, this pixel determines that light of the alignment wavelength has been detected. FIG.
(B) shows an enlarged view of another pixel, and (d) shows the amount of light received by this pixel. The definition of the oblique line is the same as that in FIG. 9A, and in this case, since it is lower than the reference value, it is determined that the light of the alignment wavelength is not detected. As described above, in one pixel, the detection reference differs depending on how the reference light amount is set. That is, in one pixel, the position information cannot be detected with an accuracy smaller than the short width M. Therefore, in the present invention, the value of the reference value P is changed stepwise as shown by P1 to P4 as shown in FIG. This will be specifically described. Assume that the initial reference value is P
Set to 1. Then, since the light reception amount of the detected light of the alignment wavelength at this time is larger than the reference value P1, it is determined that the light of the alignment wavelength is detected. Next, the reference value is changed from P1 to P2. In this state as well, the received light amounts of the light having the alignment wavelength are similarly compared, and it is determined that the light having the alignment wavelength has been detected. next,
Next, the reference value is changed from P2 to P3, and the same processing is performed. Next, the reference value is changed from P3 to P4. At this time, since the amount of light received at the alignment wavelength is smaller than the reference value P4, it is determined that no light is detected. Then, the system controller 50 can detect the ratio of the area of the light-transmitting region and the area of the non-light-transmitting region in this pixel due to the change in the signal from the pixel accompanying the change in the reference values P3 to P4. In the CCD line sensor, the same processing is performed for all pixels. Therefore, judging from the detection results of adjacent pixels, the boundary line between the light-transmitting region and the light-impermeable region in the short width M is determined. You can determine if there is. As described above, by changing the reference value to be compared with the amount of received light in one pixel in several steps, position information can be detected with an accuracy smaller than the size of one pixel constituting the linear sensor. Specifically, the reference value can be changed in about 20 steps, but is not limited to this number.

In this manner, the position information of the projection image RM 'of the film side mark FM and the reticle side mark is detected, and the system controller determines the feed direction (X direction),
It is calculated how much the reticle R should be moved in the width direction (Y direction) and further in the rotation direction (θ direction) to perform positioning. Then, a signal is sent to the reticle position adjustment mechanism R10, and the servo motor 12 is driven to perform the alignment. When the alignment is completed, the light irradiated on the reticle R is switched from the light of the alignment wavelength to the light of the exposure wavelength, or the main illumination light is emitted in addition to the illumination of only the alignment portion, and the wiring pattern RP is Projection exposure is performed on one frame F10. When the projection exposure of one frame F10 is completed, the next one frame is transported to the exposure position, and the same operation is repeated.

In this embodiment, the explanation has been made by using the exclusive film side mark. However, the present invention is not limited to this, and perforation can be used. Although the film-side mark has been described in the form of a square, the present invention is not limited to this. The hole may be a hole symmetrical with the center, such as a round hole. Further, the alignment mark is not limited to a round shape but may be a square shape.

[0022]

As described above, according to the method of aligning a film and a reticle in the film exposure apparatus of the present invention, since a CDD line sensor is used as a means for detecting a projected image of an alignment mark, an area senna is used. The detection speed is faster than. Further, when detecting the projection image at each pixel, the reference value to be compared with the amount of light received at each pixel is changed, so that the alignment can be performed with an accuracy smaller than the detectable area of the pixel.

[Brief description of the drawings]

FIG. 1 is a schematic view of a film exposure apparatus of the present invention.

FIG. 2 shows a reticle in the film exposure apparatus of the present invention.

FIG. 3 shows one frame of a film in the film exposure apparatus of the present invention.

FIG. 4 is a diagram showing a detection unit in the film exposure apparatus of the present invention.

FIG. 5 is an explanatory diagram relating to detection by a CCD line sensor according to the present invention.

FIG. 6 is a diagram for explaining a reference value related to detection according to the present invention.

[Explanation of symbols]

 10: Irradiation unit 20: Projection lens 30: Stage 40: Detection unit 49: CCD line sensor 50: System controller R: Reticle F: Film RM: Reticle side mark RM ': Projected image of reticle side mark FM: Film side mark

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-191741 (JP, A) JP-A-4-147147 (JP, A) JP-A-1-295261 (JP, A) JP-A-2- 93305 (JP, A) JP-A-61-131441 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03F 7/20-9/02 H05K 3/00

Claims (1)

(57) [Claims] 1. A film exposure apparatus in which a plurality of frames arranged on a belt-like film are sequentially conveyed to an exposure position, and a wiring pattern on a reticle is exposed to the film by a light from an irradiation unit via a projection lens. In the method for aligning a film and a reticle, at least two or more film-side alignment marks are formed on each frame of a strip-shaped film, and a wiring pattern projected and transferred to the film is formed on the reticle along with a film-side alignment mark. A reticle-side alignment mark is formed corresponding to each of the alignment marks, and when the film is conveyed to the exposure position, the projected images of the film-side alignment mark and the reticle-side alignment mark are projected on a CCD line sensor, and the CCD line The amount of light detected by each pixel constituting the sensor Is compared with a preset reference value, in each pixel, the position of the projected image of the film-side alignment mark and the reticle-side alignment mark is determined, and those data are input to a system controller. A method of aligning a film and a reticle in a film exposure apparatus, wherein the same operation is repeated a plurality of times while changing a reference value, and thereafter, the reticle is moved to a correct position by a signal from a system controller.