KR20090118507A - Laser repair system - Google Patents

Abstract

PURPOSE: A laser repair system is provided to reduce a focusing error due to a height change of an object to be repaired by controlling a focus correcting lens. CONSTITUTION: A laser repair system(1) includes an optical part, a focus driving part, and a control part. The optical part(21) includes a laser oscillator, an objective lens, and a focus correcting lens. The laser oscillator emits a laser beam. The objective lens focuses the laser beam emitted from the laser oscillator. The focus correcting lens is positioned between the laser oscillator and the objective lens. The focus correcting lens has a refractive force smaller than a refractive force of the objective lens. The focus correcting lens is movably installed in order to control a focus of the objective lens. A focus driving part(24) moves the focus correcting lens according to an optical axis of the laser beam. The control part(25) controls the focus driving part in order to focus the laser beam irradiated from the optical part to a desired position of user.

Description

Laser repair system

The present invention relates to a laser repair system, and more particularly, to a laser repair system capable of focusing adjustment of a laser beam.

The laser repair system is a device that performs a repair using a laser beam for defects among semiconductor and LCD panels that have been determined to operate normally in a test process such as semiconductor and LCD panels.

In the case of a memory semiconductor wafer, the laser repair system repairs a defective die by using a fuse formed in the wafer and information about its address, and then repairs the fuse of the defective die through a laser and connects it with a redundancy circuit. This can reduce the defect rate of the die generated in the manufacturing process to increase the production yield, it is possible to reduce the manufacturing cost.

As shown in FIG. 1, the conventional laser repair system includes an optical unit 13 for repairing a chuck 12 loaded on a defective semiconductor wafer 11 and a wafer 11 loaded on the chuck 12. , The chuck transfer unit 14 for precisely conveying the chuck 12 on which the wafer 11 is placed and aligned with the optical unit 13, the deflection mirror adjusting unit 15 for adjusting the deflection mirror in the optical unit 13, and the overall It includes a control unit 15 for controlling the operation.

Specifically, the optical unit 13 is equipped with a laser oscillator, the laser beam emitted from the laser oscillator reaches the wafer 11 by the optical configuration inside the optical unit 13 to cut the defective fuse and The wafer 11 is repaired by connecting the associated address with another normal address.

By the way, in order to cut the defective fuse, the laser beam irradiated from the optical unit 13 must be precisely controlled to focus the correct point of the fuse. However, an error occurs in focusing of the irradiated laser due to the minute height difference generated when the chuck transfer part 14 moves and the surface height difference generated during the wafer manufacturing process. It can cause problems.

In order to solve this problem, by adding an objective lens adjusting unit 16 for moving the objective lens that performs the focusing function up and down in the optical unit 13, the focusing error of the laser beam caused by the aforementioned height difference is corrected. It was.

However, there is also a problem in moving the objective lens for such correction. That is, since the refractive power of the objective lens is very large, a high resolution motor is required to control it, and because the size of the objective lens is large, there is an alignment error in the internal configuration of the optical unit 13 due to disturbance such as vibration caused by the movement of the objective lens. Cause.

An object of the present invention for solving the above problems, can effectively reduce the focusing error caused by the height change of the object to be repaired, the difference in the fine height generated during the movement of the chuck transfer unit and the surface height generated during the wafer manufacturing process To provide a laser repair system that can reduce the focusing error caused by the difference, and can reduce the focusing error without moving the objective lens.

A feature of the present invention for achieving the above technical problem relates to a laser repair system for repairing defects such as a panel having a microstructure such as a wafer or an LCD, the laser repair system, and a laser oscillator for emitting a laser beam And an objective lens for focusing the laser beam emitted from the laser oscillator, and a focus compensation interposed between the laser oscillator and the objective lens and having a refractive power smaller than that of the objective lens and movably installed to adjust the focus of the objective lens. An optical unit including a lens; A focus driver for moving the focus correcting lens along the optical axis of the laser beam; And a control unit controlling the focus driver so that the laser beam irradiated from the optical unit is focused at a desired position of the user.

The laser repair system may further include a chuck transfer unit configured to transfer the chuck loaded with the wafer to a laser beam irradiation position of the optical unit; And a sensing unit which senses a height difference between the surface of the wafer and the objective lens transferred by the chuck transfer unit, and wherein the control unit stores position information for irradiating the laser beam and stores the wafer. Controls the chuck transfer unit to transfer the wafer according to the position information when the chuck is loaded into the chuck, and irradiates from the optical unit using the height difference sensed by the sensing unit when the wafer is transferred to the corresponding position. The focus driver is controlled to focus the laser beam on the corresponding position.

The optical unit may further include a deflection mirror between the laser oscillator and the objective lens, wherein the deflection mirror reflects the laser beam emitted from the laser oscillator and deflects the deflection mirror to the objective lens. It may be located between the laser oscillator and the deflection mirror, or may be located between the deflection mirror and the objective lens.

The detection unit includes a vision module fixed to the optical unit and provided with a focus sensor, wherein the vision module captures an image of the wafer to detect a movement position of the wafer, and detects the focus sensor. The height difference between the surface of the wafer and the objective lens is measured.

The above-described control unit stores cutting position information on a cutting point on the wafer to be cut by the laser beam to repair the defect of the wafer, and uses the cutting position information when the wafer is loaded in the chuck. The chuck feeder is controlled so that the cutting point is transferred to the laser beam irradiation position of the optical unit, and when the cutting point is transferred to the laser beam irradiation position of the optical unit, the optical unit uses the height difference detected from the sensing unit. The focus driver is controlled so that the laser beam irradiated from the part is focused at the cutting point.

Here, the control unit, when the wafer is loaded on the chuck and the initial alignment is completed and the laser beam irradiated from the optical portion is focused on a specific point on the wafer loaded on the chuck between the specific point and the objective lens Controlling the sensing unit to detect an initial height difference, and controlling the sensing unit to sense a moving height difference between the cutting point and the objective lens when the cutting point is transferred to a laser beam irradiation position of the optical unit, and detecting An error value for the initial height difference and the moving height difference detected from the unit is calculated, and the focus driver is controlled to focus the laser beam irradiated from the optical unit on the cutting point using the calculated error value.

The controller generates and stores mapping data corresponding to the location information of the specific point and the location information of the cutting point using the initial height difference and the moving height difference, and the cutting point is a laser beam of the optical unit. When the data is transferred to the irradiation position, data corresponding to the cutting point is extracted from the stored mapping data to calculate the error value, and the laser beam irradiated from the optical unit is focused on the cutting point using the calculated error value. The focus driver is controlled so as to.

In addition, the wafer may be a semiconductor memory wafer, and the cutting point may be provided as a fuse formed in the semiconductor memory wafer.

As described above, the laser repair system according to the present invention can reduce the focusing error caused by the height change of the object to be repaired by adjusting the focus compensation lens.

In particular, when the object to be repaired is a semiconductor wafer, the focusing error due to the height difference formed on the wafer surface during manufacturing and the height difference due to the transfer of the chuck transfer unit can be corrected, and the movement of the objective lens applied in the conventional laser repair system The focusing error can be corrected without the burden of vibration and ultra precision control.

Hereinafter, with reference to the accompanying drawings will be described the configuration and operation of the laser repair system according to an embodiment of the present invention.

2 is a schematic diagram of a laser repair system according to an embodiment of the present invention.

As shown in FIG. 2, the laser repair system 1 according to the present exemplary embodiment includes an optical unit 21, a chuck transfer unit 22, a detection unit 23, a focus driver 24, and a controller 25. It is composed.

In brief description of the present embodiment, the laser repair system 1 according to the present embodiment is an apparatus for repairing the wafer 27, and uses the wafer position by using cutting position information on the cutting point to be cut by the laser beam. When the cutting point of 27 is transferred to the laser beam irradiation point of the optical unit 21 and the cutting point is transferred to the laser beam irradiation point of the optical unit 21, the height difference detected from the sensing unit 23 is used. To adjust the focus of the laser beam.

Hereinafter, each structure of the laser repair system 1 which concerns on a present Example is demonstrated.

First, the optical unit 21 will be described with reference to FIG. 3. As shown in FIG. 3, the optical unit 21 includes a laser oscillator 21a, an objective lens 21b, a focus correction lens 21c, and a deflection mirror 21d.

Here, the laser oscillator 21a serves to emit a laser beam. The laser oscillator 21a emits a laser beam in a wavelength band capable of cutting metal material.

The objective lens 21b serves to focus the laser beam emitted from the laser oscillator 21a. The objective lens 21b is a lens having high refractive power and is an expensive optical mechanism. The focusing of the laser beam made by the objective lens 21b should be corrected according to the height difference between the objective lens 21b and the cutting point. That is, when the height difference between the objective lens 21b and the cutting point is changed according to the minute height difference according to the movement of the chuck transfer part 22 and the surface height generated during the manufacturing process of the wafer 27, the focusing of the laser beam is focused. Should also be corrected.

While some of the conventional invention has moved the objective lens 21b to correct the focusing, the objective lens 21b is fixedly arranged in this embodiment.

The focus correcting lens 21c is located between the laser oscillator 21a and the objective lens 21b to correct a change in focusing caused by the height difference between the objective lens 21b and the cutting point. This focusing change is possible by moving the focus correcting lens 21c along the optical axis of the laser beam. That is, the focusing correction can be performed by refraction of the laser beam emitted from the laser oscillator 21a using the focus correction lens 21c to change the direction and width of the incident beam incident on the objective lens 21b. That is, the focusing of the objective lens 21b is adjusted by the change of the laser beam refracted by the focus correction lens 21c incident on the objective lens 21b.

In FIG. 3, the deflection mirror 21d is interposed between the focus correcting lens 21c and the objective lens 21b. However, the deflection mirror 21d reflects the laser beam emitted from the laser oscillator 21a and the objective lens 21b. ) And does not affect the above-described focusing correction.

Although the focus correction lens 21c is located between the laser oscillator 21a and the deflection mirror 21d, the focus correction lens 21c may be disposed between the deflection mirror 21d and the objective lens 21b. There is no change in the principle of focusing correction described above.

Adjusting the focusing through the focus correction lens 21c in this manner does not require high precision control as adjusting the focusing through the objective lens 21b.

Since the refractive power of the focus correction lens 21c is about 1/100 smaller than the refractive power of the objective lens 21b, the tolerance according to the movement control of the focus correction lens 21c for the focusing correction is the objective lens 21b. This is because it is about 100 times larger than the tolerance according to the movement control of. In addition, since the ultra-corrective lens 21c is relatively inexpensive and compact compared to the objective lens 21b, there is little burden on the increase in manufacturing cost.

The chuck transfer unit 22 will be described with reference to FIG. 2. As shown in FIG. 2, the chuck transfer unit 22 performs a function of moving the chuck along the X axis and the Y axis, and moves the chuck 26 loaded with the wafer 27 to the laser beam of the optical unit 21. Transfer to the irradiation position. By this transfer, the height difference between the objective lens 21b and the surface of the wafer 27 may vary.

The sensing unit 23 will be described with reference to FIG. 2. The sensing unit 23 operates integrally with the optical unit 21 and includes a visual sensor capable of capturing and detecting the X and Y axis moving positions of the wafer 27 as an image, and the sensing unit 23 includes: A focus sensor for measuring the height difference between the surface of the wafer 27 and the objective lens 21b is provided.

Here, the sensing unit 23 may be provided as a vision module such as a CCD camera having a focus sensor unit.

May be provided as a vision module. The sensing unit 23 detects the height difference between the cutting point of the wafer 27 transferred by the chuck transfer unit 22 and the objective lens 21b.

The sensing unit 23 monitors whether a predetermined cutting point of the wafer 27 is accurately moved to the irradiation position of the optical unit 21. Usually, the sensing unit 23 may be provided as a CCD camera having a focus sensor unit.

The focus driver 24 shown in FIG. 2 uses the height difference sensed by the detector 23 to laser the focus correction lens 21c so that the laser beam irradiated from the optical unit 21 is focused at the cutting point. Move along the optical axis direction of the beam.

Finally, the control part 25 is demonstrated with reference to FIG. The control unit 25 stores cutting position information Xb, Yb, and Zb for the cutting point B. FIG. Cutting position information may be obtained through a wafer 27 inspection step in advance.

The control unit 25 uses the stored cutting position information Xb, Yb, and Zb to move the chuck transfer unit 22 such that the cutting point B of the wafer 27 is transferred to the laser beam irradiation position of the optical unit 21. To control. That is, the chuck transfer part 22 is a wafer 27 from the position (Xa, Ya) of the time point when the wafer 27 is loaded on the chuck 26 and the initial alignment is completed, the position (Xb, Yb) of the cutting point B. ).

In addition, when the cutting point B is transferred to the laser beam irradiation position of the optical unit 21 by the chuck transfer unit 22, the controller 25 adjusts the height difference Zb detected by the detection unit 23. The focus driver 24 is controlled so that the laser beam irradiated from the optical unit 21 is focused at the cutting point B.

Specifically, referring to FIG. 4, the controller 25 may determine that a specific point A on the wafer 27 loaded on the chuck 26 is completed by the wafer 27 being loaded on the chuck 26 and the initial alignment is completed. When the laser beam irradiated from the optical unit 21 is focused on Ya, the height difference Za between the specific point A of the wafer 27 and the objective lens 21b is detected through the sensing unit 23. Detect. At this time, the position information on the specific point (A) corresponds to {Xa, Ya, Za}.

In addition, the control unit 25 controls the chuck transfer unit 22 by using the stored cutting position information B: Xb and Yb to move the wafer 27 from the specific point A to the cutting point B. In the case of the movement, the height difference Zb between the cutting point B and the objective lens 21b is detected using the detector 23. At this time, the position information on the cutting point (B) corresponds to {Xb, Yb, Zb}.

In addition, the controller 25 calculates error values for the height differences Za and Zb detected at the specific point A and the cutting point B described above. This error value can be obtained by (Za-Zb).

The control unit 25 adjusts the focus correction lens 21c so that the laser beam irradiated from the optical unit 21 is focused on the cutting point B using the calculated error value. That is, a control signal corresponding to the calculated error value is applied to the focus driver 24 to move the focus compensation lens 21c.

In the above, the control unit 25 generates a control signal using the error value calculated in real time.

On the other hand, when there are a plurality of cutting points on the wafer 27, the control unit 25 moves the chuck transfer unit 22 corresponding to each of the cutting points, and cuts each using the detection unit 23. Detects the height difference corresponding to the point and generates and stores mapping data corresponding to each cut point. When the cutting point is transferred to the irradiation position of the laser beam of the optical unit 21, the corresponding data is extracted from the stored mapping data to calculate an error value, and the laser irradiated from the optical unit 21 using the error value. The focus driver 24 is controlled so that the beam is focused at the cut point.

Specifically, referring to FIG. 5, as illustrated in FIG. 5, a plurality of cutting points may be random points' B (Xb, Yb) ',' C (Xc, Yc) ',' Assuming that D (Xd, Yd) 'and the height difference corresponding to each cut point B, C, D is detected as' Zb', 'Zc', 'Zd', respectively, each cut point B, C And mapping data for D) are formed as 'B (Xb, Yb, Zb)', 'C (Xc, Yc, Zc)', and 'D (Xd, Yd, Zd)', respectively. The error values corresponding to the cutting points B, C, and D may be 'Za-Zb', 'Za-Zc', or 'Za-Zd'. 'Za' is the same as described above with reference to FIG. 4.

 The control unit 25 generates a control signal by extracting data corresponding to the cutting point from the stored mapping data to cut the arbitrary cutting points 'B', 'C', and 'D' as described above. The focus driver 24 is controlled by the generated control signals. By the control of the focus driver 24, the focus correction lens 21c is driven to focus the laser beams irradiated from the optical unit 21 on the cutting points 'B', 'C' and 'D'.

As described above, in the laser repair system 1 according to the exemplary embodiment, the height difference and the chuck transfer part 22 formed on the surface of the wafer 27 are manufactured by automatically adjusting the focus correction lens 21c described above. Focusing error due to the height difference according to the transfer of the can be corrected, focusing error can be corrected without the burden of vibration and ultra-precision control according to the movement of the objective lens 21b as in the conventional laser repair system (1).

The embodiment presented here is limited to the repair system of the semiconductor wafer, but may be applied to a panel having a microstructure such as an LCD.

The laser repair system according to the present invention can be widely used as a semiconductor device for repairing using a laser beam generated in a panel having a microstructure such as a semiconductor wafer.

1 is a schematic diagram of a laser repair system according to the related art.

2 is a schematic diagram of a laser repair system according to an embodiment of the present invention.

3 is a schematic diagram illustrating an operation of a controller according to an embodiment of the present invention.

4 is a view for explaining the operation of the controller according to an embodiment of the present invention.

5 is a diagram for describing mapping data according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

21, 51: optical portion 21a: laser oscillator

21b: objective lens 21c: focusing lens

22: chuck transfer unit 23: detection unit

24, 54: focus driver 25: control unit

Claims (8)

In the laser repair system for repairing defects such as a panel having a microstructure such as a wafer or an LCD, A laser oscillator for emitting a laser beam, an objective lens for focusing the laser beam emitted from the laser oscillator, and positioned between the laser oscillator and the objective lens and having a refractive power smaller than the refractive power of the objective lens and focusing the objective lens. An optical unit including a focus correction lens movably installed to adjust; A focus driver for moving the focus correcting lens along the optical axis of the laser beam; And A controller configured to control the focus driver to focus the laser beam radiated from the optical part at a desired position of the user; Laser repair system characterized in that it comprises. The method of claim 1, The laser repair system, A chuck transfer unit for transferring the chuck loaded with the wafer to a laser beam irradiation position of the optical unit; And a sensing unit configured to sense a height difference between the surface of the wafer and the objective lens transferred by the chuck transfer unit. The control unit stores position information for irradiating the laser beam, controls the chuck transfer unit to transfer the wafer according to the position information when the wafer is loaded in the chuck, and transfers the wafer to a corresponding position. And focus the control unit so that the laser beam irradiated from the optical unit is focused at the corresponding position by using the height difference sensed by the sensing unit. The method of claim 1, The optical unit further comprises a deflection mirror between the laser oscillator and the objective lens, the deflection mirror reflects the laser beam emitted from the laser oscillator and deflects the objective lens, The focus correcting lens is positioned between the laser oscillator and the deflection mirror, or between the deflection mirror and the objective lens. The method of claim 2, The detection unit, It is fixed to the optical unit is made of a vision module having a focus sensor, The vision module captures an image of the wafer, detects a moving position of the wafer, and measures a height difference between the surface of the wafer and the objective lens using the focus sensor. The method of claim 2, The control unit, To store the cutting position information for the cutting point on the wafer to be cut by the laser beam to repair the defect of the wafer, and when the wafer is loaded into the chuck, the cutting point information is used by using the cutting position information. The chuck transfer unit is controlled to be transferred to the laser beam irradiation position of the optical unit, and when the cutting point is transferred to the laser beam irradiation position of the optical unit, the laser is irradiated from the optical unit using the height difference sensed by the sensing unit. And the focus driver to control a beam to be focused at the cutting point. The method of claim 5, The controller is configured to initialize an initial height between the specific point and the objective lens when the wafer is loaded on the chuck and the initial alignment is completed and the laser beam irradiated from the optical unit is focused on a specific point on the wafer loaded on the chuck. Controlling the sensing unit to detect a difference, and controlling the sensing unit to sense a difference in moving height between the cutting point and the objective lens when the cutting point is transferred to the laser beam irradiation position of the optical unit, and from the sensing unit Calculating an error value for the detected initial height difference and the moving height difference, and controlling the focus driver to focus the laser beam irradiated from the optical part on the cutting point by using the calculated error value. Laser repair system. The method of claim 6, The controller generates and stores mapping data corresponding to the location information of the specific point and the location information of the cutting point using the initial height difference and the moving height difference, and the cutting point is a laser beam of the optical unit. When the data is transferred to the irradiation position, data corresponding to the cutting point is extracted from the stored mapping data to calculate the error value, and the laser beam irradiated from the optical unit is focused on the cutting point using the calculated error value. Laser repair system, characterized in that for controlling the focus drive unit. The method of claim 5, The wafer is a semiconductor memory wafer, and the cut point is a fuse formed in the semiconductor memory wafer.

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