JPH0771756B2 - Laser trimming device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser trimming device for processing thin films and trimming fine wiring.

2. Description of the Related Art In recent years, a method has been used in which an active matrix array / IC memory or the like used in a liquid crystal display device has a redundant configuration and a defective portion is cut or processed to improve a manufacturing yield. If the active matrix array has more than 1 million picture elements and the IC memory has more than 4 Mbytes, the manufacturing department can hardly be expected unless a redundant configuration is taken. It is effective to use laser light for processing or cutting the above-mentioned redundant portion, and therefore, a laser trimming device capable of fine and excellent processing is required.

Hereinafter, a conventional laser trimming device will be described with reference to the drawings. FIG. 6 is a block diagram of an embodiment of a conventional laser trimming device. In FIG. 6, 601 is an object to be processed (hereinafter referred to as a processed substrate) such as an active matrix array substrate / IC memory semiconductor substrate, 602 is a positioning means such as an XY stage, and 603 is a YAG.
YAG laser light generating means for generating a laser, 604 is the YA
The laser beam 608 generated by the G laser generation means 603 is processed substrate 6
01 is a laser optical system having a condensing optical system for condensing and irradiating, 605 is a control means for controlling irradiation / light irradiation of laser light of the YAG laser light generating means 603, and 606 is a processing substrate 601. A monitor means such as a television camera for monitoring the trimming state.

Next, the operation of the conventional laser trimming device will be described. First, the processed substrate 601 is loaded on the positioning means 602. Next, while observing the surface of the processed substrate 601 with the monitor means 606, the positioning means 602 is used to perform positioning so that the processed portion comes to the laser light irradiation position. When the positioning is completed, the switch provided in the control means 605 is pushed. Then, the YAG laser light generation means 603 operates the Q switch and the like provided inside by the switch to generate pulsed laser light having a large leading value power. The laser light is condensed by the laser optical system 604, has a high power density, and is applied to the irradiation position of the processed substrate 601.

Problems to be Solved by the Invention Hereinafter, in order to clarify problems of a conventional laser trimming device, description will be given with reference to the drawings. One of the uses of the laser trimming device is cutting of defective portions of an IC memory active matrix array. When the cut portion has a single-layered structure of a metal thin film, the range of laser irradiation conditions is relatively wide and processing is easy. 2. Description of the Related Art In recent years, semiconductor substrates and the like have a multi-layer structure for high density and high integration. Therefore, there is a demand for cutting the wiring formed in the lower layer inside (hereinafter referred to as internal wiring). However, the internal wiring is made of an insulating material or another component around the internal wiring. The laser irradiation conditions for cutting the internal wiring without damaging the peripheral portion are very narrow, and good cutting is difficult. Here, an active matrix array formed on a glass substrate will be described as an example. FIG. 7A is a front view of the internal wiring portion of the active matrix array formed on the glass substrate 204. FIG. 7 (b) is a sectional view taken along the line AA 'in FIG. 7 (a). FIG. 7 (a) (b)
In 201, 201 is an internal wiring processed by laser light, 204 is a transparent substrate such as glass, and 205 is an insulating film such as SiNx or SiO ₂ . 7 (a) and 7 (b), the structure is drawn very simply to facilitate drawing, and the film thickness direction is drawn greatly exaggerated. For example, the glass substrate has a thickness of 1 mm, and the internal wiring / insulator film has a thickness of 1 to 2 μm.

The above also applies to the following drawings. Also,
Items with the same numbers and symbols have the same contents, or
It has the same configuration.

FIGS. 8A and 8B are explanatory views for explaining a method of cutting the internal wiring 201 by the conventional trimming device. In FIGS. 8A and 8B, 801 is an optical image and 802 is a locus of laser light. The laser light is condensed by the laser optical system 604, passes through the insulating film 205, and heats the internal wiring 201. In order to improve the cutting property, the conventional laser trimming device is designed to use a Q switch to maximize the head value power of the laser pulse and to shorten the irradiation time of the laser light to 50 nsec or less. Therefore, the internal wiring 201 heated by the laser light expands and evaporates rapidly. Fig. 9 (a)
(B) is a plan view or a sectional view of the internal wiring 201 after processing. FIG. 9A shows an example in which only the both ends of the internal wiring 201 are processed and the central part is not processed because the laser power is small. This occurs because the thermal conductivity differs between the central portion and both end portions of the internal wiring. FIG. 9B shows an example in which the upper insulating film 205 is destroyed.
This is because the internal wiring 201 was vaporized in a large amount because the laser power was too large, and the upper insulating film 205 was destroyed. In this case, if another structure is formed on the insulator film 205, the product becomes a defective product, and even if it is not formed, the internal wiring comes into contact with the atmosphere and the reliability is significantly deteriorated. By changing the laser power from a small state to a large state, the state shown in FIG. 9 (a) is changed to the state shown in FIG. 9 (b). However, the variable range of the laser power with respect to the change from FIG. 9 (a) to FIG. 9 (b) is very small. This is because the conventional laser trimming device performs processing with the magnitude of the head value power of the laser pulse.
It is difficult to control the leading value power because the variation is large. The conventional laser optical system 604 is a condensing optical system. Therefore, the power density in the optical image 801 is large in the central part and small in the peripheral part and is not uniform. Therefore, the processing state greatly changes due to the positional deviation of the optical image 801.

From the above, the laser irradiation condition range is very narrow,
Further, the thickness is further narrowed due to variations in the film thickness of the insulator film 205. Therefore, it was difficult to perform trimming almost satisfactorily.

In order to solve the conventional problems, the trimming device of the present invention has a Q switch, and a laser beam generating unit that generates a laser beam by turning on and off the Q switch; and the laser beam. First and second slit means for transmitting a predetermined region of the laser light generated by the generating means, and first and second optical images of the laser light transmitted through the first and second slits are processed. It is provided with an image forming optical system for forming an image so that at least a part of the first and second optical images overlaps with the processing position of the object. An image is formed on the object to be processed. Therefore, it is possible to superimpose two optical images having a uniform power density on the processing positions. Also, the size position of the optical image and the power density can be adjusted individually.

Embodiment A laser trimming apparatus according to a first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a laser trimming device according to the first embodiment of the present invention. In FIG. 1, 102a and 102b are first and second laser light generating means. The laser light generating means is internally provided with a Q switch, and by turning the Q switch on and off, pulsed laser light is generated. The laser wavelength is 1.06 of YAG laser.
.mu.m or the second high frequency of 0.53 .mu.m is used, preferably 1.06 .mu.m. This is because the light absorptivity of the object to be processed decreases due to a long wavelength and apparently the application control of the laser power becomes easy. Further, the half width of the laser pulse is used a few nm ~ 1000 nm, preferably
Set to 20nm-300nm. Reference numeral 101 is a control means for controlling the first and second laser light generating means, which controls synchronous control of the start of laser light irradiation, the number of irradiation laser pulses, and the like. Reference numerals 103a and 103b denote transmitting means, which are provided with slits for preventing irradiation of the laser light to a portion unnecessary for processing, and can form the laser light into a rectangular optical image. 104
a and 104b are image forming means, which are provided with an image forming optical image,
An optical image transmitted through the slit can be formed on the processed substrate. Reference numeral 105 denotes a monitor unit that can observe the state of the surface of the processed substrate 107.

Reference numeral 106 denotes a stacking unit for the processed substrate 107. The loading means can hold a switching element forming surface such as a processed substrate such as an active matrix array substrate downward and hold the switching element forming surface at a peripheral portion of the substrate so that an object does not contact the element forming surface. When the image forming means does not have a means for positioning the laser beam at the processing position, a positioning means for positioning the processing position manually or by a program is provided. An XY stage or the like is used as the positioning means. Preferably loading means
It is preferable that 106 is automatically controlled by a control means (not shown) capable of exchanging data with the control means 101, and is controlled so that the machining points can be positioned one after another. 108 is a mirror, 109 is a half mirror, 110
・ 111 and 112 are laser beams. Note that the positional relationship between the mirror 108, the half mirror 109, etc. is shown for ease of explanation, and is not limited to this.

The operation of the laser trimming device according to the first embodiment of the present invention will be described below. First, the stacking means 106 and the monitor means 105 are used to perform initial positioning using a positioning mark (not shown) formed on the processed substrate 107, hereinafter referred to as an alignment mark), and then the stacking means 106 is operated. Then, the positioning is performed so that the laser beam is irradiated to the first processing position. When the positioning is completed, the control means 101 sends a command to the first and second laser light generation means, controls the Q switch, and irradiates the laser light in synchronization. As the irradiation timing of the laser light,
The difference between the irradiation times of the first and second laser beams is controlled to 10 msec or less, preferably 1 msec or less. Further, the irradiation times of the two laser beams can be separated as needed. The laser light is collimated and guided to the first and second transmitting means. The laser light is converted into a rectangular optical image at the irradiation position of the processed substrate by the slit or the like included in the transmitting means. Next, the laser light passing through the transmitting means is imaged on the processed substrate by the first and second imaging means. A plurality of pulses of the laser light are applied to the same position on the processed substrate, and the internal wiring at the processed position is gradually trimmed with weak laser power. When the processing of one location is completed by the above procedure, the next processing location is positioned and the processing is performed one after another.

Hereinafter, trimming of internal wiring by the laser trimming device of the present invention will be described. 2 (a) and 2 (b) are explanatory views of the trimming method by the trimming device of the present invention. In FIG. 2A, 201 is an internal wiring, 202 is an optical image (hereinafter referred to as a first optical image) by the laser light emitted by the first laser light generating means 102a, and 203 is a second laser light generating means 102b. Is an optical image (hereinafter, referred to as a second optical image) by the laser light emitted by the laser. Further, FIG. 2 (b) shows the second
It is a sectional view taken along line BB ′ of FIG. In FIG. 2B, reference numeral 204 is a transparent substrate such as glass, 206 is a locus of laser light emitted by the first laser light generation means 102a (hereinafter referred to as a first laser light locus), and 207 is a second laser light. Generating means 102b
The locus of the laser beam emitted by the laser beam (hereinafter referred to as the second laser beam locus). As is apparent from FIG. 2 (a), the second optical image 20
The first optical image 202 is projected so as to overlap 3. For example, the power densities in the two optical images are made the same. Therefore, twice the electric power is applied to the portion where the two optical images overlap. The power density of each irradiation laser beam is substantially uniform because the imaging optical system is used as the optical system.

Further, as shown in FIG. 2B, the laser light is transmitted through the substrate 204 to heat the internal wiring 201. FIG. 3A is a plan view when the processing of the internal wiring of the processed substrate is completed. FIG. 3 (b) is a sectional view taken along the line CC 'of FIG. 3 (a).
The internal wiring at the processed portion is well removed. The removed constituents are condensed at the interface with the insulator film 205 or the like to become bulk and solidify. According to the laser trimming device of the present invention, as shown in FIG. 9 (a), the second optical image 203 can be irradiated to the central portion of the internal wiring which is difficult to cut. Therefore, it can be cut well. Also, 2
Since it is possible to irradiate a required portion with a required laser power by using one optical image, the upper insulating film 205 is not destroyed as shown in FIG. 9B.

A laser trimming device according to a second embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a block diagram of a laser trimming device according to the second embodiment of the present invention. In FIG. 4, 401a and 401b are first and second dimming means. The dimming unit dims the laser power and can adjust to a predetermined laser power for each laser pulse to be emitted. For example, laser light generation means
When oscillating at 1 kHz and irradiating laser pulses at 1 kHz intervals, the laser power can be reduced to a predetermined value within 1 msec. Examples of the dimming means include what is called an AO attenuator that electrically changes the amount of transmission. As described above, adjusting the laser power for each laser pulse is because the processing surface at the first pulse processing point is a mirror surface and the absorption of laser light is not good, but at the next laser pulse the first laser pulse is used. The part is processed,
Since the absorption rate of laser light is improved, it is possible to process with a weak laser power. Therefore, by reducing the laser power from the second pulse onward, the same laser power is applied to the processed portion on average,
Good cutting is possible. The control means 101 controls the first and second dimming means for each laser pulse to control the laser power. The other parts are the same as those of the laser trimming device of the first aspect of the present invention.

The operation of the laser trimming device according to the second embodiment of the present invention will be described below. First, using the stacking means 106 and the monitor means 105, initial positioning is performed by an alignment mark (not shown) formed on the processed substrate 107. Next, the stacking means 10 is operated to perform positioning so that the laser beam is emitted to the first processing position. When the positioning is completed, the control means 101 sends a laser light irradiation command to the first and second laser light generation means 102a and 102b. The laser light generation means 102a and 102b irradiate the laser light based on the command.

The laser light is dimming means 401a, 402 for each laser pulse.
It is dimmed to a predetermined value by b. Normally, the dimming means 401a and 401b are controlled to gradually reduce the laser power of the laser pulse applied to one location, but if there is no problem in the cutting property of the processing location, they are controlled to a constant dimming value. In some cases.
When the processing at one location is completed, the next processing location data is read from the storage means (not shown) with the next processing position data, and the next processing location is processed in the same manner.

As described above, in the laser trimming apparatus according to the second embodiment of the invention, the laser power for each laser pulse can be controlled, so that the laser absorptance at the processed portion can be made substantially constant for each laser pulse. Due to the above, good processing or cutting is possible.

Although the laser trimming device of the present invention is provided with the first and second image forming means, the present invention is not limited to this, and the image forming means 50 as shown in FIG.
1 may be placed.

Further, as shown in FIG. 5 (b), the laser light generated by one laser light generating means is divided into laser light 110 and 111 without providing the first and second laser light generating means,
It is obvious that each laser beam may be incident on the first and second dimming means.

Further, the positional relationship between the image forming means and the mirror does not limit the apparatus of the present invention. Further, in the second embodiment of the present invention, the positional relationship among the dimming means, the transmitting means, and the image forming means is not limited to this. For example,
The dimming unit may be inserted after the transmitting unit or after the image forming unit.

Further, as shown in FIG. 5 (b), it is obvious that the laser light generated by one laser light generating means may be divided into two and the two optical images may be overlapped. As described above, the present invention does not specify the number of laser light generators, but is configured to superimpose a plurality of laser light optical images of the laser light generating means.

EFFECTS OF THE INVENTION In the laser trimming device of the present invention, two optical images can be superposed on the processing position. Therefore, by overlapping the two optical images at the cutting position where the cutting residue is likely to occur, the power density applied to the above-mentioned location becomes large, and the cutting residue does not occur. Moreover, since the image forming optical system is used, the power density in the optical image can be made uniform. Therefore, the internal wiring can be satisfactorily cut without destroying the periphery and the upper layer film.

Further, in the second embodiment, a dimming means is provided and the laser power can be controlled for each laser pulse. Therefore, it is possible to perform processing in consideration of the processing position configuration state and the absorption rate of the laser power for each laser pulse irradiation.
Therefore, it is possible to perform more optimal processing / cutting as compared with the first embodiment.

[Brief description of drawings]

FIG. 1 is a block diagram of a laser trimming device according to a first embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are explanatory diagrams for explaining a trimming method by the laser trimming device of the present invention, and FIG. (A) (b), FIG. 9 (a) (b)
Is a plan view and a cross-sectional view of an object to be trimmed, FIG. 4 is a block diagram of a laser trimming device according to a second embodiment of the present invention, and FIGS. 5A and 5B are laser trimming of the present invention. FIG. 6 is a block diagram of another embodiment of the device, FIG. 6 is a block diagram of a conventional laser trimming device, and FIG.
FIGS. 8A and 8B are a plan view and a cross-sectional view of an object to be processed,
(A) and (b) are explanatory views for explaining a trimming method by a conventional trimming device. 101,605 ... Control means, 102a, 102b ... Laser light generating means, 103a, 103b ... Transmission means, 105,606 ... Monitoring means,
106 …… Loading means, 107,607 …… Processing object, 108 …… Mirror, 109,607 …… Half mirror, 110,111,112,608 ……
Laser light, 201 ... Wiring, 202 ... First optical image, 203 ...
Second optical image, 204 ... Substrate, 205 ... Insulator film, 206 ...
First laser beam locus, 207 ... Second laser beam locus, 401a, 40
1b ... dimming means, 501 ... imaging means, 502 ... laser light generation means, 602 ... positioning means, 603 ... YAG laser light generation means, 604 ... laser optical system, 801 ... optical image, 802 ...
… Laser light trajectory.

Claims (2)

[Claims] 1. A laser beam generator having a Q switch and generating a laser beam by turning the Q switch on and off, and a first region for transmitting a predetermined region of the laser beam generated by the laser beam generator. And the second slit means and the first and second optical images of the laser light transmitted through the first and second slits, and at least one of the first and second optical images at the processing position of the processing object. A laser trimming device comprising an image forming means for forming an image so that the parts overlap each other. 2. The laser trimming device according to claim 1, further comprising a dimming unit capable of varying at least one of the laser powers of the first and second optical images for each laser pulse.