JPH051112B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a processing device using a laser,
In particular, it relates to a laser trimming device used in redundancy technology that converts defective addresses in highly integrated IC memories fabricated on semiconductor wafers to spare addresses by blowing out address switching fuses.

[Conventional technology]

FIG. 3A is a block diagram of a conventional laser trimming device. Conventionally, this type of laser trimming device consists of a laser oscillator 1, an attenuator 2, and a slit 3.
It has an imaging lens 4, a wafer stage 5, a stage driver 6, and a controller 7,
The wafer 8 to be processed is mounted on the wafer stage 5 under the control of the controller 7 under the control of the controller 7 and the fuse to be blown is positioned at the focal position of the imaging lens 4 by the stage driver 6 based on the processing information that has been determined in advance by an IC test system or the like. be done. A laser beam output from a laser oscillator 1 is attenuated by an attenuator 2 to the optimum energy for processing, and then irradiated onto a slit 3.

The slit 3 has the structure shown in FIG. 3B, and is configured such that the size of the opening 10 can be arbitrarily changed within a predetermined range by adjusting the amount of overlap between the two slit plates 9a and 9b. The laser beam that has passed through the opening 10 of the slit 3 forms an image of the opening 10 of the slit 3 on the fuse to be blown of the wafer 8 to be processed by the imaging lens 4, and blows the fuse.

In addition, in other types of laser trimming apparatuses as shown in FIG.
A positioning device 11 is fixed on the top and positions a part of the optical system from the laser oscillator 1 to the imaging lens 4.
There is also one that moves and positions itself over the fuse to be fused.

[Problem that the invention seeks to solve]

Generally, a fuse has a shape as shown in FIG. 5A, and has a width of 1 to 3 microns and a length of more than ten microns. Also, future highly integrated memory ICs
Further miniaturization and higher density are inevitable, and in order for the image of the opening 10 of the slit 3 shown in FIG. Precision is required. However, when blowing the fuse shown in FIG. 5A, positioning accuracy in the X direction is sufficient if the fuse length Lx is sufficient, but in the Y direction it is necessary to keep the fuse width Ly within.
In the conventional laser trimming device, the shape of the image is exactly the shape of the opening 10 of the slit 3 in FIG. 3, and for the fuse shown in FIG. 5A, the shape of the opening 10 of the slit 3 is Kx It is set in a rectangular shape and positioned as shown in Figure B. According to this, the required positioning accuracy in the Y direction is
It has the effect of being relaxed due to the direction length Ky. However, it is fully expected that the direction of the fuse will be not only in the X direction as shown in FIG. 5A, but also in the Y direction in order to gain more freedom in chip design in future highly integrated memory ICs. When blowing the fuse of such an IC memory that has fuses in both the X and Y directions, conventional laser trimming equipment blows the fuses in the X direction as described above, but the The image will be positioned as shown in Figure 5C. In this case, it is obvious that the required positioning accuracy in the X direction becomes stricter. In addition, if the length Kx of the image formation in the X direction is increased, the required positioning accuracy will be eased, but the area irradiated with laser energy will become larger.
This is not desirable considering the effect of heat on the IC chip. In addition, the shape of the opening 10 of the slit 3 is
It is possible to change the shape to a rectangle with a longer Y-direction side that matches the fuse, as shown in Figure D, but if there are many X-direction fuses and Y-direction fuses, the time required to change the shape is equal to the time required to blow one fuse. Since the amount is relatively large, the processing capacity of the laser trimming device will be reduced.

[Means for solving problems]

The laser trimming device of the present invention includes a laser oscillator, a splitter that divides one laser optical axis output from the laser oscillator into two, and a splitter that is located on the two divided laser optical axes, A shutter for independently shielding/transmitting laser light, and a shutter located on the two bisected laser optical axes,
A slit whose aperture shape can be changed independently, an integrator that integrates the two laser beam axes transmitted through the shutter and the slit into one laser beam axis, and a consolidator located on the laser beam axis to adjust the energy of the laser beam. It has an attenuator that can arbitrarily attenuate.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of a first embodiment of the present invention. A laser beam 12 outputted from a laser oscillator 1 is adjusted by an attenuator 2 to optimal energy for fuse blowing. Furthermore, half mirror 13a
and a total reflection mirror 13b.
The laser beam is split into two axes of equal energy. Shutters 16a and 16b are inserted on each of the two divided optical axes, which can block/transmit laser light at high speed in response to an electric signal from the controller 15. The aperture shape of the laser light passing through each shutter 16a, 16b can be changed, and the beam cross-sectional shape is limited to the aperture shape of each slit by the slits 17a, 17b having the same aperture area. slit 17
The biaxial laser beams that have passed through a and 17b are combined into a coaxial beam by an integrator 19 that combines a half mirror 18a and a total reflection mirror 18b. The coaxially integrated laser beams are imaged by the imaging lens 4 onto the wafer 8 to be processed as images of the slits 17a and 17b.

Generally, in laser trimming equipment, the IC is
The processing information measured and determined by a test system or the like is input to the controller 15 using a recording medium such as a floppy disk or a means such as a local area network. The fuses to be fused are blown by a laser beam while being sequentially positioned at the imaging position of the imaging lens 4. In the laser trimming apparatus of the present invention, fuse direction information is added to the processing information using a software programming method. slit 17
a, 17b have slits 17 as shown in Figure 6 A, B.
a has an opening in the X direction, and a slit 17b has an opening in the Y direction.
Provide an opening in the direction. The controller 15 sequentially positions the fuses to be blown on the wafer 8 to be processed at the imaging positions of the imaging lens 4 based on the processing information, and also controls the shutters 16a and 16b based on the direction information of the fuses, regardless of whether the fuses to be blown are in the X direction. If the fuse to be blown is in the Y direction, the shutter 16a is controlled to be shielded and the shutter 16b is controlled to be transparent. Therefore, if the fuse to be blown is in the X direction, a laser beam having a shape as shown in FIG. 5B is irradiated, and if it is in the Y direction, a laser beam having a shape as shown in FIG. 5D is irradiated.

A shielding plate or the like may be mechanically inserted into the shutters 16a and 16b on the optical axis if necessary.
If an acousto-optic element, which is generally used as a light modulation element or the like, is used, it is possible to switch between transmission and shielding at extremely high speed, and the reduction in processing performance due to shutter switching is minimal.

Furthermore, the slits 17a and 17b may be replaced by a metal plate 20 with various openings 10 as shown in FIG. 7A, or a metal plate 21a having a shape as shown in FIG. 7B. , 21b can be changed to arbitrarily change the shape of the opening 10.

In addition, the splitter 14 is one that can split a single-axis laser beam into two-axis laser beams, and the integrator 19 is one that can integrate two-axis laser beams into one-axis laser beam, as shown in this embodiment. The mirror is not limited to a half mirror or a total reflection mirror, and for example, a polygon mirror (rotating polygon mirror) can also be used.

FIG. 2 is a block diagram of a second embodiment of the present invention. In this embodiment, the attenuator 2 in the first embodiment is installed as attenuators 2a and 2b in the laser optical axis after being divided into two axes, and other than that, the attenuator 2 in the first embodiment is the same as the first embodiment. , has the same effect as the first embodiment. In this embodiment, since the energies of the two axes of laser light can be set individually, there is no problem even if there is an energy difference between the two axes of laser light in the splitter 14 and the integrator 19. Further, depending on the installation environment such as the distance between the fuse and the adjacent circuit, there may be a mixture of fuses that are preferably blown when a larger image is formed and fuses that are preferably blown when a smaller image is formed. In this case, the shutter 16a, 1
The aperture area of each of the apertures 6b may be set to the optimum aperture area and shape, but the difference in aperture area causes a difference in the energy of the laser beam after passing through the shutter. In this embodiment, since attenuators 2a and 2b are installed on each of the two laser optical axes, the energy of the laser light after passing through the shutters 16a and 16b is equalized even if the opening areas and shapes of the shutters 16a and 16b are different. It is possible to obtain two images with the optimum energy for processing.

〔Effect of the invention〕

As explained above, the present invention enables fusing while selecting two types of image formation at high speed depending on the direction in which the fuse is installed. Even when there are fuses in different directions, stable processing results can be obtained without affecting the positioning accuracy of the laser trimming device.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a block diagram of another embodiment of the present invention, Figs. 3A and 4 are block diagrams of a conventional example, and Fig. 3B is a block diagram of a conventional example. 3A is a plan view showing the slit in A, FIG. 5 is a plan view showing a general fuse and the imaging position of the laser beam, and FIG.
FIGS. 7A and 7B are a plan view showing the slit in FIG. 1, and FIGS. 7A and 7B are a perspective view and a plan view showing the slit in FIG. 1... Laser oscillator, 2, 2a, 2b... Attenuator, 3... Slit, 4... Imaging lens, 5...
... Wafer stage, 6 ... Stage driver, 7 ... Controller, 8 ... Wafer to be processed, 9a, 9b ... Slit plate, 10 ... Opening, 11 ... Positioning device, 12 ... Laser light, 13a ... ...half mirror, 13b...total reflection mirror, 14...divider, 15...controller, 16a, 16b...shutter, 17a, 1
7b...slit, 18a...half mirror, 1
8b... Total reflection mirror, 19... Integrator, 20...
...Metal plate, 21a, 21b...Metal plate.

Claims (1)

[Claims] 1. A laser oscillator, a splitter that divides the single laser optical axis output from the laser oscillator into two, and a splitter that is located on the two divided laser optical axes and independently shields/shields each laser beam. A shutter for transmitting the laser beam, a slit that is located on the two bisected laser optical axes and whose aperture shape can be changed independently, and a slit that connects the two laser optical axes that passed through the shutter and the slit to one axis. A laser trimming device characterized by having an integrator integrated into a laser optical axis and an attenuator located on the laser optical axis and capable of arbitrarily attenuating the energy of the laser beam.