JP2880317B2 - Film exposure method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to, for example, TAB (Tape A).
The present invention relates to a film exposure method suitable for manufacturing a film circuit board used for mounting electronic components of a utomated bonding type.

[0002]

2. Description of the Related Art Photolithography is known as a technique for performing fine processing on the surface of an object. This technology has been applied not only to semiconductor integrated circuits but also recently to the manufacture of film circuit boards used for mounting TAB-type electronic components.

However, if a circuit pattern to be transferred is misaligned, a mounting error occurs in the case of a circuit board, so that an image of a photomask pattern is formed in a reference exposure area, which is a correct position of a film to be conveyed. Alignment is required to be exposed. The accuracy of the alignment is required to be, for example, within ± 10 μm.

Conventionally, as this alignment method, first, before exposure processing, an exposure sample is arranged on a stage, and the position of the photomask is adjusted so that the exposure sample and an image of the pattern of the photomask are formed. Then, the exposure sample is removed, and the reference exposure area of one frame of the film is correctly positioned at the position where the exposure sample was located.

As means for correctly positioning the reference exposure area at the position where the exposure sample was placed, the film transport distance by the feed roller is set in advance by an encoder or the like, and a sprocket roller is placed in front of the exposure surface to transport in the transport direction. Means to improve the precision of the film, and further, for one frame of the film transported and stopped at a preset distance, raise the stage having the positioning pin, and move the positioning pin to the lower side of the perforation of one frame of the film. There is a known means for performing alignment in a plane perpendicular to the optical axis by fitting from one another, and holding down one frame of the film pushed up by the stage with a holding plate to perform alignment in the optical axis direction. ing.

As described above, in the conventional alignment, only one frame of the film to be exposed is arranged at a position which is determined to be correct with respect to the photomask. That is, no feedback control is performed on the film during the exposure.

[0007]

However, there is a limit in accuracy in setting the transport distance and mechanical positioning using a sprocket roller, positioning pins, etc., and it is necessary to perform positioning within ± 10 μm as required. Can not. That is, the belt-like film may be slightly meandering instead of being perfectly straight, and even if the film is forcibly transported straight by the sprocket roller, the film may be displaced and transported on the stage. Also,
If the sheet is conveyed with a deviation exceeding the allowable limit, the perforations are damaged and spread when the positioning pins are fitted, and the accuracy is further reduced. In particular, for example, thickness 30μ
For a thin film of m or less, a method using positioning pins cannot be adopted.

On the other hand, there has been disclosed means for exposing a pattern image to one frame of a film by displacing the stage after fixing the film on the stage (see Japanese Patent Application Laid-Open No. 1-298362). By this method, the accuracy of the position adjustment is improved to some extent. However, in such a method, since the weight of the stage is large, a large driving force is required to displace the stage. In addition, the time required for alignment is long, and the accuracy of position adjustment is not sufficient. When the film is displaced in the width direction to correct the meandering of the film, an unnecessary tensile force may be applied to the band-shaped film.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to project an image at a correct position without inserting a positioning pin into a perforation, and to form a pattern. It is an object of the present invention to provide a film exposure method in which the accuracy of the exposure transfer position is higher.

[0010]

Film exposure method of the present invention, in order to solve the problem] is a film exposure method in the length direction of the belt-shaped film sequentially exposing the circuitry pattern, and the irradiation unit,
A photomask on which a circuit pattern is formed, which is arranged at a position irradiated with light from the irradiation unit, a photomask position adjusting mechanism for adjusting the position of the photomask in the same plane, and an irradiated photomask A projection lens for projecting the image of
Using an exposure apparatus comprising and a full Irumu transport mechanism you step feed by frame, wherein the strip of film, perforation meshing sprockets roller of the film transport mechanism is formed as a column lined on both sides, each column Of the perforations, a perforation having a specific positional relationship with respect to a reference exposure area where a circuit pattern is to be exposed is defined as a reference perforation, and the photomask has a circuit pattern to be projected and transferred onto a film, and an alignment mask. A mark is formed, and the positional relationship between the alignment mark and the circuit pattern on the photomask corresponds to the positional relationship between the reference perforation and the reference exposure area, and the film transport mechanism steps one frame of the film forward. and, after the step feed, Arai Alignment that has been irradiated in cement for the mark
Light through the reference perforation
Then, based on the detection signal, the position of the photomask is controlled by driving the position adjustment mechanism of the photomask so that the image of the alignment mark is projected at the position of the reference perforation for the stopped one frame, Thereafter, exposure of the circuit pattern is performed.

[0011]

[Action] positional relationship of the circuit patterns on the photo mark for alignment formed in the photomask mask, since the correspondence of the positional relationship between the reference perforations and the reference exposure area, irradiating the alignment marks Arai
Ment light through reference perforation
Thus, based on the detection signal, the position control mechanism of the photomask is driven by driving the position adjustment mechanism of the photomask so that the image of the alignment mark is projected at the position of the reference perforation for one frame of the stopped film. Is performed, the image of the circuit pattern on the photomask is exposed to the reference exposure area with high accuracy. Therefore, the exposure processing with high projection position accuracy can be performed. Further, even when the film is conveyed with a misalignment, the position of the photomask is changed accordingly, so that the position accuracy of the projected image is increased. In addition, since the position of the relatively lightweight photomask is adjusted, the position can be adjusted with a small driving force, and unnecessary stretching force is not applied to the belt-like film.

[0012]

FIG. 1 is an explanatory view of a film exposure apparatus used in an embodiment of the present invention. This apparatus sequentially exposes the circuit pattern of the photomask M along the length direction of the belt-shaped film F.

Reference numeral 10 denotes an irradiating unit, such as an ultra-high pressure mercury lamp, which efficiently emits light whose resist has sensitivity.
11 built-in.

M is a photomask, which is arranged at a position where light from the irradiation unit 10 is irradiated. As shown in FIG. 2, on the photomask M, an alignment mark MM is formed corresponding to each of the below-described reference perforations BP, together with a circuit pattern MP to be projected and transferred onto the film F. The alignment mark MM is configured by providing a cross-shaped transparent portion on a rectangular opaque portion. The irradiation light for alignment guided by the optical fiber 15 from the irradiation unit 10 (dotted line in FIG. 4)
After the optical performance is adjusted in the alignment illumination unit 16, the alignment mark MM is irradiated via the mirror 17. On the other hand, during exposure, irradiation light indicated by a solid line in FIG. 4 is applied to the circuit pattern MP.

As shown in FIG. 3, a rectangular perforation P in which a feed roller 61 and a sprocket roller 64 of a film transport mechanism 60 to be described later mesh with each other is formed as a row on both sides of the belt-like film F, as shown in FIG. Here, the size of the perforations P is, for example, 2 mm square, and the pitch is, for example, 4.75 mm. BA indicated by a virtual line (two-dot chain line)
Is a reference exposure area where the circuit pattern is to be exposed. BP is a reference perforation having a specific positional relationship with respect to the reference exposure area BA among the perforations P in each row. In one frame F10, the film F
Are provided in the width direction. The positional relationship between the reference perforation BP and the reference exposure area BA corresponds to the positional relationship between the alignment mark MM of the photomask M and the circuit pattern MP on the photomask M. MM 'is an image of an alignment mark, and the image MM' of the alignment mark is a film including a reference perforation BP, that is, a film projection position of an image by a projection lens, by a movement operation of a photomask M described later. F
Are scanned on the virtual surface FK of the perforation P and the upper surface of the perforation P. In this embodiment, the reference perforation BP and the alignment marks MM are
Are provided in the width direction of the film. However, the present invention is not limited to this.

M10 is a photomask position adjusting mechanism, which includes a photomask holder M11 and a servomotor M12. When the servo motor M12 is driven by a signal from a system controller 50 described later, the photomask holder M11 moves and the photomask M is controlled to follow. The photomask holder M11 is capable of adjusting the position of the photomask M in two directions (X direction and Y direction) perpendicular to each other in a plane perpendicular to the optical axis, and is capable of adjusting the position of the photomask about the optical axis. Adjustment for rotating the mask M (adjustment of θ) is possible. Therefore, the servo motor M12 for driving the photomask holder M11 is X, Y,
Actually, three are provided so that each of θ can be driven.

Reference numeral 20 denotes a projection lens for projecting the illuminated image of the photomask M. This projection lens 20
Has a resolution of, for example, an exposure line width of about 5 μm.

Reference numeral 30 denotes a stage. As shown in FIG. 4, the upper surface is a reference surface, and is provided with a vacuum suction hole 31 for blowing air when the film F is fed stepwise and for vacuum suctioning the film during exposure. . 32 is a vacuum pump, 34
Is a valve. In this example, the vacuum suction hole 31 also serves as a reverse air hole for floating the film F with air when the film F is step-fed, 33 is a compressor, and 35 is a valve. Numerals 36 and 37 cause the front and rear portions of the film F to float during the step feeding of the film F. The valves 34 and 35 are controlled by a signal from a system controller 50 described later.

Reference numeral 40 denotes a detection unit.
As shown in (1), it is a unit type having an objective lens 41, a condenser lens 42, and a detector 43. In this example, the detection unit 40 is embedded in the stage 30 and the objective lens
Reference numeral 41 denotes a position facing the perforation P of the film F. The detector 43 is a converter made of a high-sensitivity photoelectric conversion element, for example, a phototube or a photodiode. Further, an image sensor can be used as the detector 43. 44 is an amplifier.

Reference numeral 50 denotes a system controller including a CPU.

Reference numeral 60 denotes a film transport mechanism for step-feeding one frame F10 of the film F to a position where an image is projected by the projection lens 20. The feed roller 61 is a sprocket roller driven by a motor 62. Motor 62
Is driven by a signal from the system controller 50, is decelerated by a signal from the system controller 50 as described later, and then stops by a signal from the system controller 50 that has received a signal from the detection unit 40. 63 is a press roller, 64 is a sprocket roller, 65 is a press roller,
66 and 67 are auxiliary rollers, 68 is a take-out reel, and 69 is a take-up reel .

Next, an embodiment of the film exposure method of the present invention using the film exposure apparatus of FIG. 1 will be described. When one frame F10 of the film F is step-advanced by the film transport mechanism 60, the reference perforation BP relating to this one frame F10 becomes an image MM 'of the alignment mark.
The detection unit 40 detects whether the position has been reached.

First, the system controller 50 sends the motor
When a drive start signal is sent to the motor 62 and the motor 62 rotates at the constant speed v ₁ in FIG. 5 and feeds the film F, and when the time reaches t ₁ in FIG. speed is reduced to v ₂ in Fig. The t ₁ of time is previously set according to the length or the like of one frame F10 of the film. While being decelerated in the v _2, it receives a stop signal from the system controller 50 which processes the signal from detector 40, the motor 62 stops rotating. This time is shown in FIG.
T ₂ .

The generation of the stop signal by the system controller 50 is performed as follows. As shown in FIG.
When one frame F10 of the film is sent and the reference perforation BP corresponding to one frame F10 reaches the projection position of the image MM ′ of the alignment mark, the light of the alignment wavelength transmitted through the reference perforation BP as a hole ( The detection unit 40 generates a signal according to the dotted line in FIG. 4). FIG. 6 shows the change over time of the signal intensity. As shown in FIG. 4, two detectors 40 are provided corresponding to each column of the perforations P, so that two signals in the form shown in FIG. 6 are sent to the system controller 50. However, since the feed direction of the film F is not normally a perfect right angle to the width direction, the signals from the two detectors 40 are sent with a slight shift in time. Therefore, in this embodiment, the system controller 50 performs signal processing so as to generate a stop signal at the time of falling of the signal from the detection unit 40 (T _{3 in} FIG. 6) which is input with a delay. 62 is completely stopped (t _{2 in} FIG. 6). Note that the time at which the motor 62 is completely stopped by the stop signal from the system controller 50 is not limited to the falling time (T _{3 in} FIG. 6) of the signal from the detection unit 40 input late. By setting the correction value in advance, any of the slow rising, the fast falling, and the fast rising may be used. If the speed is reduced in this way and then stopped by a signal from the detection unit 40, the accuracy of the stop position becomes very high.

When one frame F10 of the film is stopped by a stop signal from the system controller 50, a signal is sent from the system controller 50 to the valves 34 and 35 to close the compressor 33 and open the vacuum pump 32.
Thus, the frame F10 is vacuum-adsorbed to the stage 30.

In this state, the position of the photomask M is controlled. That is, the photomask position adjusting mechanism M10 is driven so that the corresponding alignment mark image MM 'is projected onto each position of the reference perforation BP of one frame F10, and the position of the photomask M is shifted in the X direction and in the X direction. The position of the photomask M is adjusted by performing tracking control while moving in the Y direction and rotating about the optical axis.
More specifically, when the position of the photomask M is scanned in the X direction along the feed direction, as shown in FIG. 6, the electric signal generated in the detection unit 40 is such that the image MM ′ of the alignment mark is the reference perforation BP. a rising portion T ₁ start overlap, a flat portion T ₂ overlapping area therebetween is substantially constant, the image M of the mark for alignment
M ′ has a pulse-like waveform including a falling portion T _{3 at} which the M ′ starts to deviate from the reference perforation BP. Therefore, the position to stop the photomask M final in the X direction, it is preferable overlapping area of the mark is set to the position at time t ₃ when corresponds to, for example, the center of the flat portion T ₂ is the maximum. Accordingly, the system controller 50 stores information on the position of the photomask M when scanning and the value of the signal from the detection unit 40 at that time, and processes these to determine the optimum position of the photomask M in the X direction. Then, a drive signal is sent to the servo motor M12.

In the same manner as described above, the photomask M is also scanned in the Y direction to generate a signal at the detection unit 40. The signal processing of the system controller 50 determines the optimum position of the photomask M in the Y direction. A drive signal is sent to the servo motor M12 in the direction. The position adjustment in the X direction and the Y direction is performed using one of the detection units 40. After the position adjustment in the X direction and the Y direction is completed, scanning is performed by rotating the photomask M about the optical axis while receiving a signal from the other detection unit 40. At this time, the signal from the other detection unit 40 also has the same shape as that in FIG. 6. Therefore, the rotation direction (θ direction) is determined by the information on the rotation angle of the photomask M and the value of the signal from the detection unit 40 at that time. The optimal position of the photomask M is determined, and a drive signal is sent to the servo motor M12 in the θ direction. Thus, the X, Y, θ of the photomask M
Is adjusted. After the positioning of the photomask M is completed as described above, the sharp cut filter described above is retracted so that the light of the exposure wavelength is emitted from the irradiation unit 10, and the frame F10 held at the projection position is removed. Then, the circuit pattern MP of the photomask M is exposed.

According to the exposure method of the present embodiment, the positional relationship between the alignment mark MM formed on the photomask M and the circuit pattern MP is determined by the reference perforation BP.
Since then it corresponds to the positional relationship between the reference exposure area BA and, A
Alignment light applied to alignment mark MM
Is detected through the reference perforation BP
Based on the detection signal, the photomask position adjusting mechanism M10 is driven so that the alignment mark image MM 'is projected at the position of the reference perforation BP corresponding to one frame F10 of the stopped film F. If the position of the photomask M is controlled, the exposure image of the circuit pattern MP is exposed to the reference exposure area BA with high accuracy. Further, even when the film F is displaced and conveyed, the position of the photomask M is changed accordingly.
The positional accuracy of the projected image is increased, and adjustment is possible with an accuracy of, for example, about 10 μm. In addition, since the position of the relatively lightweight photomask M is adjusted, the position can be adjusted with a small driving force, and the belt-shaped film F is not affected.

[0029]

According to the film exposure method of the present invention, A
The alignment light applied to the alignment mark
Simple to detect via reference perforation
By using such means, the image of the circuit pattern on the photomask is exposed to the reference exposure area with high accuracy, and an exposure process with high projection position accuracy can be performed. Further, even when the film is conveyed with a misalignment, the position of the photomask is changed accordingly, so that the position accuracy of the projected image is increased. In addition, since the position of the relatively light photomask is adjusted, highly accurate position adjustment can be performed with a small driving force, and the belt-shaped film is not affected.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a film exposure apparatus used in an embodiment of the present invention.

FIG. 2 is an explanatory front view of a photomask.

FIG. 3 is an explanatory front view of a film.

FIG. 4 is an explanatory view of a main part of the apparatus shown in FIG. 1 as viewed from a film feeding direction.

FIG. 5 is a speed curve diagram of a motor.

FIG. 6 is a waveform diagram of a detection signal.

[Explanation of symbols]

 10 Irradiation unit 11 Lamp 15 Optical fiber 16 Alignment illumination unit 17 Mirror 20 Projection lens 30 Stage 31 Vacuum suction hole 32 Vacuum pump 33 Compressor 34 Valve 35 Valve 36 Lift roller 37 Lift roller 40 Detector 41 Objective lens 42 Condenser lens 43 Detector 44 Amplifier 50 System controller 60 Film transport mechanism 61 Feed roller 62 Motor 63 Press roller 64 Sprocket roller 65 Press roller 66 Auxiliary roller 67 Auxiliary roller 68 Unwind reel 69 Take-up reel M Photomask M10 Photomask position adjustment mechanism M11 Photomask Holder M12 Servo motor MP Circuit pattern MM Alignment mark MM 'Image of alignment mark F Film P Perforation BP Reference perforation BA Reference exposure area

Continuation of front page (56) References JP-A-1-298362 (JP, A) JP-A-54-96374 (JP, A) JP-A-2-100036 (JP, A) JP-A-51-115825 (JP, A) JP-A-51-140488 (JP, A) JP-A-57-91245 (JP, U)

Claims (1)

(57) [Claims] 1. A strip of successively exposing the circuitry pattern lengthwise film exposure method of the film, the irradiation portion, disposed at a position where light is irradiated from the irradiation portion, the circuit A photomask on which a pattern is formed, a photomask position adjustment mechanism for adjusting the position of the photomask in the same plane, a projection lens for projecting an image of the irradiated photomask, and a projection position of the image by the projection lens film using an exposure apparatus comprising and a full Irumu transport mechanism you step feed frame by frame to, wherein the strip of the film, forming a row aligned perforations meshing sprocket roller of the film transport mechanism on each side Of the perforations in each row, the perforations having a specific positional relationship with respect to the reference exposure area where the circuit pattern is to be exposed. An alignment mark is formed on the photomask together with a circuit pattern to be projected and transferred onto a film. The positional relationship between the alignment mark and the circuit pattern on the photomask is determined by the reference perforation. Corresponds to the positional relationship between the reference exposure area and the reference exposure area, and the film transport mechanism step-feeds one frame of the film .
Alignment light is passed through the reference perforation
The position of the photomask is controlled based on the detection signal by driving the position adjustment mechanism of the photomask so that the image of the alignment mark is projected at the position of the reference perforation for one stopped frame. And then exposing the circuit pattern.