JPH051113B2 - - 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 schematic 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, which has been measured and determined in advance by an IC test system, etc., is mounted on the wafer stage 5, and the fuse to be blown between the wafer and the wafer is imaged by the stage driver 6 under the control of the controller 7 according to the processing information obtained. It is positioned at the focal position of the lens 4. A laser beam outputted 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 the opening 1 is formed by adjusting the amount of overlap between the two slit plates 9a and 9b.
The structure is such that the size of 0 can be changed arbitrarily within a predetermined range. Opening 1 of slit 3
The laser beam that has passed through 0 is focused by the imaging lens 4 on the fuse to be blown of the wafer 8 to be processed as an image of the opening 10 of the slit 3, and blows the fuse. In another type of laser trimming apparatus as shown in FIG. Some move and position over the fuse to be blown. The present invention can be commonly applied to various laser trimming devices regardless of the means for positioning the laser beam onto the fuse to be blown on the wafer, so the following explanation will be given to the conventional laser trimming device shown in FIG. I will only write about it.

[Problem that the invention seeks to solve]

Generally, fuses on semiconductor wafers are shown in Figure 5A.
It has a rectangular shape with a width of 1 to 3 microns and a length of more than ten microns. In addition, further miniaturization and higher density are inevitable in future highly integrated memory ICs, and in order for the image of the opening 10 of the slit 3 shown in FIG. 6 is 1
Positioning accuracy on the order of microns or less 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.
The shape is set to a rectangle of Kx×Ky, and the position is determined as shown in Figure B. According to this, the required Y
The positioning accuracy in the direction is reduced by the Y-direction length Ky of the image formation. 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. Furthermore, if the length Kx of the image formation in the X direction is increased, the required positioning accuracy can be relaxed, but the area irradiated with laser energy becomes larger, which is not preferable in view of the influence of heat on the IC chip. It is also possible to change the shape of the opening 10 of the slit 3 to a rectangle with a longer Y-direction side that matches the fuse, but if there are many X-direction fuses and Y-direction fuses, the time required to change the shape is only one. Since the time required to blow the fuse is longer than the time required to blow the fuse, the processing capacity of the laser trimming device is reduced.

In contrast to the conventional laser trimming device described above, the laser trimming device according to the present invention is capable of quickly switching the optimal shape of the image for each of the fuses in the X and Y directions. It is unique in that it does not reduce processing performance or reliability even when mixed memory ICs are used.

[Means for solving problems]

The laser trimming device of the present invention includes a laser oscillator, an optical axis switcher that switches a single laser optical axis output from the laser oscillator to two laser optical axes, and a laser trimming device located on the switched two laser optical axes, A slit whose aperture shape can be changed independently, and a slit that passes through the optical axis switch and the slit.
It has an integrator that integrates two laser optical axes into one laser optical axis, and an attenuator that is located on the laser optical axis and can arbitrarily attenuate the energy of the laser beam.

〔Example〕

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

FIG. 1 is a block diagram showing a first embodiment of the present invention. The laser beam 12 output from the laser oscillator 1 is arbitrarily switched into two-axis laser beams (optical axis A 15a, optical axis B 15b) by an electric signal from a controller 14 at an optical axis switch 13. Attenuators 16a are provided on the two optical axes, respectively.
16b, and the power of each of the two axes of laser light can be adjusted to an arbitrary value by an electric signal from the controller 14. The aperture shape of the laser beam that has passed through each attenuator 16a, 16b can be changed, and the beam cross-sectional shape is limited to the respective slit aperture shape by slits 17a, 17b having the same aperture area. The biaxial laser beams that have passed through the slits 17a and 17b are combined into coaxial beams by an integrator 19 that combines a total reflection mirror 18a and a half 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 14 using a recording medium such as a floppy disk or a means such as a local area network, and the controller determines the fuse to be blown on the wafer 8 to be processed based on the data. The fuses to be blown are fused with laser light 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 and 17b have slits 17 as shown in Figure 6 A and B.
a has an opening in the X direction (A in the same figure), and a slit 17
An opening in the Y direction (B in the figure) is provided in b.
Based on the processing information, the controller 14 sequentially positions the fuses to be blown on the wafer 8 to be blown at the imaging positions of the imaging lens 4, and also controls the optical axis switch 13 based on the direction information of the fuses so that the fuses to be blown are in the X direction. If so, control is performed to switch to optical axis A, and if the fuse to be blown is in the Y direction, to switch to optical axis B. 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.

If an acousto-optic element, which is generally used as a light modulation element, is used as the optical axis switch 13, it is possible to switch the optical axis at extremely high speed, and the decrease in processing performance due to optical axis 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 integrator 19 does not necessarily use the half mirror or total reflection mirror shown in this embodiment, as long as it can integrate two-axis laser light and one-axis laser light. Optical axis switcher 1 allows you to set the energy of the two axes of laser light individually.
3. There is no problem even if there is an energy difference between the two axes of laser light in 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 aperture areas of the slits 17a and 17b may be set to optimal aperture areas and shapes, but the difference in aperture area causes a difference in the energy of the laser beam after passing through the slits. In this embodiment, an attenuator 1 is provided for each of the two laser optical axes.
Since 6a and 16b are installed, slit 17
Even if the aperture area and shape of a and 17b are different, the energy of the laser light after passing through attenuators 16a and 16b can be made equal, and two images with optimal energy for processing can be obtained.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

In this embodiment, the attenuators 16a and 16b in the first embodiment are installed as an attenuator 16 in the laser optical axis before the two-axis division, and other than that, the attenuators 16a and 16b in the first embodiment are the same as in the first embodiment. It has the same effect as the first embodiment. In this embodiment, since the energies of the two axes of laser light cannot be set individually, there is a possibility that an energy difference will occur between the two axes of laser light in the optical axis switcher 13 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 opening areas of the slits 17a and 17b may be set to the optimum opening area and shape, but the difference in opening area causes a difference in the energy of the laser light after passing through the slits 17a and 17b. Therefore, in this embodiment, when switching between two laser optical axes using the optical axis switcher 13, the attenuation rate of the attenuator 16 is switched at high speed by the controller 14 so that the energy is optimal for each optical axis. It has a possible structure. If the attenuator 16 used for this purpose is an acousto-optic element that is generally used as a light modulation element, the attenuation rate can be changed extremely quickly.

〔Effect of the invention〕

As explained above, the present invention includes a laser oscillator, an optical axis switcher that switches one type of laser optical axis output from the laser oscillator to two axes, and two optical axis switches.
a slit that is located on the laser optical axis of the book and whose aperture shape can be changed independently; an integrator that integrates two laser optical axes transmitted through the slit into one laser optical axis; and a laser optical axis. By having an attenuator located above that can arbitrarily attenuate the energy of the laser beam, it is possible to perform fusing while selecting two types of image formation at high speed according to the installation direction of the fuse, resulting in highly integrated memory. Because of the degree of freedom in circuit design in ICs, stable processing results can be obtained without affecting the positioning accuracy of the laser trimming device even when fuses installed in different directions are mixed, which is highly effective.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention,
Fig. 2 is a block diagram showing a second embodiment of the present invention, Fig. 3A is a schematic diagram of a conventional laser trimming device, Fig. 3B is a schematic structural diagram of a slit, and Fig. 4 is a schematic diagram of a conventional laser trimming device. A schematic diagram of the laser trimming device, Figures 5A, B, C, and D are schematic diagrams of the positional relationship between the fuse direction and image formation on a semiconductor wafer, and Figures 6A, B.
7 is a schematic diagram of the opening of the slit, and FIGS. 7A and 7B are schematic diagrams of the slit. 1 is a laser oscillator, 2a and 2b are conventional attenuators, 3 is a slit, 4 is an imaging lens, 5 is a wafer stage, 6 is a stage driver, 7 is a conventional controller, 8 is a wafer to be processed, 9a, 9
b is a slit plate, 10 is an opening, 11 is a positioning device, 12 is a laser beam, 13a is an optical axis switch, 14 is a controller of the present invention, 15a is an optical axis A, 15b is an optical axis B, 16a and 16b are attenuator,
17a and 17b are slits, 18a and 18c are total reflection mirrors, 18b is a half mirror, 19 is an integrator, 20 is a metal plate, and 21a and 21b are metal plates.

Claims (1)

[Claims] 1 In a laser trimming device that uses a laser to blow out the address switching fuse of an IC memory using a redundancy method,
a laser oscillator, an optical axis switcher that switches from one laser optical axis outputted from the laser oscillator to two laser optical axes, and is located on the two switched laser optical axes and independently changes the aperture shape. an integrator that integrates the two laser optical axes that have passed through the respective slits into one laser optical axis, and a consolidator that is located on the laser optical axis and can arbitrarily attenuate the energy of the laser beam. A laser trimming device characterized by having an attenuator.