JP2663558B2 - Laser processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of manufacturing a wafer once formed and inspected.
The present invention relates to a laser processing apparatus for performing reprocessing for the purpose of relieving a defective chip.

[Prior Art] Conventionally, in order to improve chip yield in an integrated circuit manufacturing process, a redundant circuit is provided for each chip. This redundant circuit is formed so that the replacement connection is made by selectively cutting the fuse, and the fuse to be cut is specified from the inspection result of each chip in the wafer.

In addition, the cutting of the fuse for relieving a defective chip is performed by selectively irradiating a predetermined fuse with a laser beam by using a laser processing apparatus having a high-level alignment mechanism different from a defect inspection apparatus (hereinafter referred to as a tester). It is done by doing.

[Problems to be Solved by the Invention] However, in a conventional laser processing apparatus, for a rescue chip in a wafer, a fuse is cut from a fixed direction according to a preset order, or a chip is narrower than one chip. Cutting was performed by setting an appropriate cutting order and cutting direction for each range (independent of other chips). Therefore, when looking at the entire wafer, the alignment of the laser beam with each fuse on the wafer was considered. However, there is a problem that the relative movement operation is very wasteful.

Further, a method of determining the cutting order and direction in which the moving operation is not wasteful for each individual wafer from the arrangement position (coordinates) of the fuse to be cut can be considered for each individual wafer. It takes a great deal of calculation time, so it is not a good idea considering cost and effect.

[Means for Solving the Problems] In the present invention, a plurality of circuit units provided on a substrate (wafer) so as to have predetermined redundant circuits which can be replaced and connected by selectively cutting fuses, respectively. A specific fuse is cut by selectively irradiating a laser beam to each chip on which an integrated circuit is formed) based on fuse cut information obtained from a test result for each circuit unit, thereby cutting off a specific portion of the substrate. A laser processing apparatus that rescues a circuit configuration of a circuit unit by replacing the circuit unit with a redundant circuit, including an inspection result for each circuit unit, a measurement direction and a measurement order for each circuit unit in the substrate when the substrate is inspected. Input means for receiving measurement information and fuse arrangement information relating to the arrangement of fuse portions in each circuit unit; and test results received by the input means Measurement information, based on the fuse arrangement information, by which a determination means for determining the optimal cutting sequence the cutting direction of fuses to be cut in the substrate, has achieved the above-mentioned problems.

[Operation] In the laser processing apparatus according to the present invention, measurement information on the measurement direction and measurement order of each chip in the wafer when the wafer is inspected, fuse arrangement information on the arrangement of the fuse section in each chip, Inspection results of the tester are received, and the optimum cutting order and cutting direction of the fuse to be cut are determined based on the information.

That is, in the step immediately before the fuse cutting step,
Since all the chips in the wafer are sequentially inspected one by one (or several chips) by the tester, the use of the measurement information on the measurement direction and measurement order of each chip at this time reduces waste in the moving operation. The cutting order and the cutting direction can be easily determined in a short calculation time.

Embodiment FIG. 1 is a block diagram showing an embodiment of the present invention. The wafer 8 is vacuum-sucked on a wafer stage 9 that can move in two orthogonal directions. The laser beam LB emitted from the laser light source 6 is bent by the mirror 11, enters the irradiation optical system 7 through the aperture 12 having a predetermined opening, is condensed into a predetermined shape, and The part is illuminated.

In such a laser processing apparatus, first, the input means 1
, The information D ₁ about the test result of each chip in the tester, the measurement related to the measurement order and the measurement direction of each chip in the tester information D _2, arrangement information D ₃ of the fuse within each chip
Are input, and these pieces of information are sent to the determination means 2.

Then, the determining means 2 determines the cutting order and the cutting direction of the fuse to be cut of the rescueable chip based on the information D ₁ , D ₂ , D ₃ . The determination of the cutting order and the cutting direction may be performed for one entire wafer. However, if the number of fuses to be cut is large, the determination should be made in units of one to several chips in consideration of the calculation time. Is preferred.

The fuse cutting order and the cutting direction determined by the determining means 2 are sent to a system control system 3 for controlling the entire processing apparatus, and the system control system 3 moves the wafer stage 9 based on the cutting order and the cutting direction. And a signal relating to the movement amount to the drive control system 4. The drive control system 4 receives a signal from the system control system 3 and controls the motor 10 (there is also another motor in the axial direction, not shown) to move the wafer stage 9 to a predetermined position. . The trigger unit 5 receives a signal from the system control system 3 when the wafer stage 9 is positioned at a predetermined position, sends a trigger signal to the laser light source 5, and causes the laser light source 5 to emit light.

In this manner, by repeating the movement of the wafer stage 9 and the irradiation of the laser beam LB, the fuses to be cut are cut one after another in the previously determined order. In the above description, a case has been described in which only the wafer stage 9 on which the workpiece is placed moves, but it goes without saying that both the wafer stage 9 and the laser beam LB may relatively move.

Next, how the fuse on the wafer is blown will be described in more detail.

FIG. 2 (a) shows a cutting path in the embodiment of the present invention (an arrow indicates cutting in that direction, and a dotted line indicates movement).
FIG. 2 (b) is an explanatory view schematically showing a conventional cutting path, and FIG. 3 is a drawing showing a measurement path with a tester in the embodiment shown in FIG. FIG. In the figure, 36 (6 × 6) chips are shown in a matrix for the sake of explanation. Although the fuses are not shown, it is assumed in this embodiment that the fuses are arranged in the horizontal direction.

First, in the tester, as shown in FIG. 3, [(x = 1, y = 1), (x = 2, y =
1)... (X = 6, Y = 1), (x = 6, y = 2). Then, [(x = 5, y =
2), (x = 2, y = 2), (x = 3, y = 3), (x = 4, y
= 3), (x = 5, y = 4), (x = 2, y = 4)] are output in this order indicating that each chip can be rescued by cutting the fuse.

In the present invention, since the measurement information on the measurement direction and measurement order of each chip in the above-described tester and the arrangement information on the arrangement of the fuses on each chip are input in advance, the cutting order of the fuse to be cut based on this information is input. And the cutting direction are determined. Specifically,
Since the moving direction in the y = 3 row when each chip is inspected by the tester is leftward, based on this, (x = 3, y =
For chips 3) and (x = 4, y = 3), the direction of fuse cutting is reversed to y = 2 rows and turned to the left. Therefore, from the chip of (x = 3, y = 3), (x = 4, y = 3)
Chip and (x = 4, y = 3) chip (x =
There is no waste in the path to the chip of (5, y = 4).

On the other hand, in the conventional example shown in FIG. 2 (b), the fuse of each chip is blown in a fixed direction (to the right) regardless of the measurement direction of the tester.
After cutting the fuse of the chip of 3, y = 3) to the right,
A wasteful operation is performed in which the same line is moved backward to the left and moved to the left end of the chip (x = 4, y = 3). Further, the moving distance for moving from the fuse cut at the end of the chip (x = 4, y = 3) to the fuse blown at the beginning of the chip (x = 5, y = 4) is also shown in the embodiment (a). ) Is longer.

Subsequently, still another embodiment will be described with reference to FIGS. In each figure, (a) shows a cutting route according to the present invention, and (b) shows a cutting route in a conventional example. Point A in the figure indicates a start reference position in the tester, and any measurement in the tester proceeds to the next row (or column) when the measurement reaches the end of the row (or column) as in FIG. It is performed by a method of moving in a direction (meandering).

First, FIG. 4 shows a case where both the measurement direction of the tester and the fuse arrangement direction are horizontal. In the conventional example (b) in which the cutting direction is fixed to the right, as shown in the figure, a chip of (x = 5, y = 4), a chip of (x = 4, y = 4), and further, (x = 5, y = 4) (X = 3, y = 4)
In the embodiment (a) of the present invention, y = 2,4
By changing the cutting direction to the left in accordance with the measurement direction of the tester in the row, the reversing operation is avoided, and the cutting path is shortened as a whole.

FIG. 5 shows a case where both the measurement direction of the tester and the arrangement direction of the fuses are vertical. Also in this case, as in the case of FIG. 4, the embodiment (a) of the present invention has no useless operation of reversing the same row, and is compared with the conventional example (b) in which the cutting direction is fixed downward in the drawing. The cutting path is much shorter.

Next, FIG. 6 shows a case where the measurement direction of the tester is the vertical direction and the fuse arrangement direction is the horizontal direction. In this case, although the measurement direction of the tester and the fuse arrangement direction are orthogonal,
In the embodiment of the present invention, as shown in (a), the cutting direction is alternately changed to right, left, right... In the same row based on the measuring direction and the measuring order in the tester so as to take a lean cutting path. ing. On the other hand, in the conventional example (b), since all are cut rightward, the movement to the next chip is performed through the diagonal line as shown in the figure, and in the case of (a) according to the present invention. The cutting path is longer. Further, in the embodiment of the present invention, in order to move to the next chip in the same row, it is only necessary to fix the x direction and perform alignment only in the y direction, whereas in the conventional example (b) moving diagonally, x, y Positioning must be performed in both directions, and the time required for positioning becomes longer.

FIG. 7 shows a case where the measurement direction of the tester is the horizontal direction and the fuse arrangement direction is the vertical direction. In this case as well, the measurement direction of the tester and the arrangement direction of the fuses are orthogonal to each other as in the case of FIG. 6, but in the embodiment (a), the directions of alternately cutting in the same row are downward, upward, and downward. … So it cuts down consistently (moves diagonally)
The cutting path is shorter than in the conventional example (b). Further, since it is only necessary to fix the y direction and position only the x direction to move to the next chip in the same row, positioning can be performed in a short time.

In the above embodiment, the case where the fuses of each chip are arranged in only one direction (only vertical and horizontal) has been described. However, fuses arranged vertically and horizontally in one chip are mixed. Needless to say, the present invention can be applied to such cases. Also in such a case, the cutting order and the cutting direction of each fuse are determined based on the measurement order and the measurement direction in the tester so that the cutting path becomes shorter.

[Effects of the Invention] As described above, according to the present invention, the information on the measurement order and the measurement direction of each chip (circuit unit) in the tester is used, so that the entire wafer can be formed with a simple operation circuit and in a short operation time. More efficient fuse cutting order and cutting direction can be determined.

By using such a device, useless operation at the time of fuse cutting can be avoided by a simple arithmetic circuit, and in consideration of cost-effectiveness, high-speed rescue operation of a defective chip can be performed very efficiently at low cost. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a laser processing apparatus according to the present invention, FIG. 2 is an explanatory diagram comparing a cutting operation in an embodiment of the present invention with a conventional example, FIG. 3 is an explanatory diagram showing a measuring order in a tester, FIGS. 4, 5, 6, and 7 are explanatory views for explaining the cutting operation in another embodiment and a conventional example, respectively. [Description of Signs of Main Parts] 1... Input means 2... Determination means 3... System control system 4... Drive control system 5... Trigger unit 6... Laser light source 7. 9 Wafer stage

Claims (2)

(57) [Claims] An inspection result for each of a plurality of circuit units provided on a substrate so as to have predetermined redundant circuits that can be replaced and connected by selectively cutting fuses in a fuse unit. A laser processing apparatus that selectively irradiates a laser beam based on fuse cutting information obtained from the above to cut a specific fuse, thereby relieving a circuit configuration of a circuit unit in the substrate by replacing it with a redundant circuit. In the above, inspection results for each circuit unit, measurement information including a measurement direction and a measurement order for each circuit unit in the board when the board is inspected, and a fuse related to the arrangement of the fuse unit in each circuit unit Input means for receiving placement information; and based on the inspection result, measurement information, and fuse placement information received by the input means, Laser processing apparatus characterized by comprising a determination means for determining the optimal cutting sequence the cutting direction of fuses to be cut in serial on the substrate. 2. The laser processing apparatus according to claim 1, wherein the determination of the cutting order and the cutting direction is performed for each of a predetermined number of circuit units.