JPH01224189A - Laser beam control method for laser beam machine - Google Patents

Abstract

PURPOSE:To perform machining at plural machining points with a high throughput by moving relatively irradiation predetermined points of a laser beam as machining objects with respect to optional machining points at a high speed to position these and subsequently, carrying out control so as to emit the laser beam for the machining points. CONSTITUTION:The title laser beam machine 1 receives the inputted inferior data BAD by a cutting order controller 31 constituted of a computer. When the distance between cutting points to continue in order is shorter than a prescribed value, the processing order of the cutting points is changed and the cutting data CUT to be the slow speed mode to send an X scanner 101 or a Y scanner 102 at the slow speed are sent in a data processor 11. When the distance between the cutting points specified in order by the inferior data BAD is longer than a prescribed changeover critical value, the inferior data BAD are inputted to the data processor 11 as the cutting data CUT as they are, by which the scanner is controlled by the ordinary positioning mode.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a laser beam control method for a laser processing apparatus, and is a control method particularly suitable for use in processing semiconductor wafers.

[Conventional technology]

Conventionally, laser processing equipment is used to cut circuit patterns or perform processing to change resistance values by irradiating laser beams onto semiconductor integrated circuit patterns formed on semiconductor wafers. There is.

For example, in semiconductor memory (RAM, ROM, etc.), 256 (K
Semiconductors designed to form memory chips with a storage capacity of 1 (M bit), 1 (M bit), etc. were mass-produced.
Furthermore, mass production of 4 (M-bin) memory chips is progressing.

In such highly integrated memory chips, redundancy (repair) is used to improve manufacturing yields.
dundancy) processing method is applied. In this redundancy process, in addition to cells with the required memory capacity, a memory circuit consisting of redundant spare cells (this is called a redundancy circuit or redundant circuit) is prepared in advance on the memory chip, for example, in a wafer blower. When a defective cell is found as a result of inspecting each cell of the memory chip, the memory chip is repaired to an acceptable product by replacing the memory circuit to which the defective cell is connected with a redundancy circuit.

FIG. 3 is a schematic diagram showing the outline of a fuse section of a redundant circuit that has recently come to be used in semiconductor memory ICs. Third
In the figure, machining points P to P13 are machined in order.

In order to realize this method, a memory chip is configured as shown in FIG. 4, for example. That is, memory chip 1
is the column direction (vertical or Y direction in Figure 4)
There are 8 memory areas MARI to MAR8, each having 512 memory cells arranged in one direction and 256 memory cells arranged in one direction (left and right, that is, the X direction in FIG. 4).
4 are arranged in each of the left and right halves.

(MARI formed on the left half of memory chip 1)
, MAR2, MAR3 and MAR4 and memory chip 1
MAR5, MAR6, MAR7 formed on the right half of
and MAR8, row decoders RO'W1 and MAR2 address the memory cells of MARI and MAR5.
A row decoder ROW2 that addresses the memory cells of MAR6, a row decoder ROW3 that addresses the memory cells of MAR3 and MAR7, and a row decoder ROW4 that addresses the memory cells of MAR4 and MAR8 are arranged.

Also, MARl and M formed in the upper half of the memory chip l
AR2, MAR5 and MAR6, and MAR3, MAR4, MAR7 and M formed in the lower half of the memory chip 1.
Column decoders CoL1, MAR3 and M which address the memory cells of MARI and MAR2 are connected to AR8.
Column decoder CoL2, which addresses the node recell of AR4, column decoder C0L3, MAR7, and MAR8, which addresses the memory cells of MAR5 and MAR6.
Column decoders C0L4 are arranged to address the memory cells of .

With this configuration, regarding redundancy processing, 512 fuse groups FVI (FIG. 5(A)) corresponding to each column line are arranged in the column decoders C0LI, C0L2, C0L3, and C0L4 at predetermined intervals in the lateral direction (that is, the X direction). (for example, 9 [μm]), and in ROW1 to ROW4, 256 fuse groups FV2 (Fig. 5(B)) corresponding to each row line are arranged in the vertical direction (i.e., (Y direction) at predetermined intervals (for example C3.
5 (μm)) and are arranged sequentially.

In this way, the fuse groups FVI and FV2 corresponding to defective memory cells in the eight memory areas MAR1 to MAR8 can be separated by laser beams.

Furthermore, fixed position acolumn decoders 5DCI and 5DC3 and spare row decoders 5DRI and 5DR2 are provided between the row decoders ROWI and ROW2, and a fixed position acolumn decoder 5 is provided between the row decoders ROW3 and ROW4.
DC2 and 5DC4 and spare row decoders 5DR3 and 5DR4 are provided.

These spare column decoders 5DCI to 5DC4 are
As shown in FIG. 6(A), the spare column line address designating fuses FV3 are sequentially arranged in the Y direction so as to maintain a predetermined interval (for example, 5 (μm)) of 10 fuses per column by two columns. . Furthermore, spare low decoder SDR1~
5DR4 has spare row line address designating fuses FV4 arranged in one row 10 in the X direction, as shown in FIG. 6(B).
The books are sequentially arranged so as to maintain a predetermined interval (for example, 5 μm) by two rows each.

These spare column line addressing fuses F
V3 and spare low line address designation fuse FV
4, by combining the 10 fuses in each column into 10 pairs of 2 fuses arranged in the X or Y direction and cutting one of the fuses in each pair, the lO bit is set to logic "1" or It was made possible to set rQJ data,
In this way, the memory cells of the column line redundancy circuits RDC1 to RDC4 corresponding to 5DCI-3DC4 are reduced to 1.
It is possible to specify by 0-bit code data, and similarly, the memory cells of the low line redundancy circuits RDRI-RDR4 corresponding to 5DRI-3DR4 can be specified by 10-bit code data.

In this way, according to the memory chip 1, the memory areas MARI, MAR2, MAR5 and MAR6 are connected to the memory blocks MBI, MAR3, MAR4, MAR7 and MA.
When R8 is set as memory block MB2, if there are two or less defective cells in each, the defective cells can be separated by cutting fuses FVI and FV2 corresponding to the address of the defective cell with a laser beam. Instead, by cutting the 10-bit spare column line address designation fuse FV3 and spare row line address designation fuse FV4 corresponding to the address of the defective cell using a laser beam, the column line redundancy circuits RDC1 to RD
C4 and low line redundancy circuits RDR1 to RD
R4 can be connected to the address location of the defective cell.

Thus, memory blocks MBI and MB2 each have 2
When there are three or fewer defective memory cells, the manufacturing yield of the memory chip 1 can be improved by repairing the defective memory cells and making the memory chip an acceptable product.

When laser processing a fuse with such a configuration, it is necessary to irradiate it with a laser beam! A fairly high accuracy (for example, about 0.3 [μm]) is required. Conventionally, a laser processing system with the configuration shown in Fig. 7 was used to realize processing that satisfies this requirement! was used.

In FIG. 7, the laser processing apparatus 1 has an A laser beam LB generated from a laser beam generation source 6 is irradiated onto the semiconductor wafer 5 via a mirror 7.

The X stage 3 and the Y stage 2 are positioned and controlled by a positioning device 10 having the configuration described below, thereby sequentially positioning the fuse to be cut at the irradiation position of the laser beam LB.

In the positioning device 10, a data processing device 11 having a computer configuration receives defective data BAD obtained in advance from a wafer prober that uses an Ic tester to inspect whether chips of a manufactured semiconductor wafer are good or defective. Data processing device 1
1 stores a reference table consisting of various data representing the configuration of the semiconductor wafer 5 to be repaired, and generates coordinate data of the fuse to be cut on the semiconductor wafer 5 by analyzing defective data while referring to the reference table. do.

This cutting fuse coordinate data DATA is set in the X position setting register 12 and the Y position setting register 13, whereas the current positions of the X stage 3 and Y stage 2 are detected by the position detectors 14 and 15 and It is taken into the position register 16 and the Y position register 17, and is also read into the X position setting register 12 in the comparators 18 and 19.
and the setting data of the Y position setting register 13.

As a result, the match detection signals C are sent to comparators 18 and 19, respectively.
When OMX and COMY are obtained, it is known that the X stage 3 and Y stage 2 are positioned at the coordinate position of the cutting fuse coordinate data DATA, and at this time, a trigger is sent to the laser beam source 6 via the AND circuit 20. A laser beam LB is generated by sending the signal TRI, and the fuse on the semiconductor wafer 5 is irradiated with the laser beam LB to cut it.

At the same time, the trigger signal TRI is input to the data processing device 11, and the process moves to the step of sending out cut fuse coordinate data DATA for the next fuse.

In addition to the above configuration, the data processing device 11 operates at a speed shown in FIG. 8 based on the difference between the coordinate position based on the cutting fuse coordinate data DATA and the current irradiation position of the laser beam LB. Command pattern 5P
Speed command data corresponding to TN is sent to digital/analog converters 21 and 22. At this time, digital/
Analog converters 21 and 22 supply speed command voltages □ and vsy corresponding to the speed command pattern to an X stage drive motor 25 and a Y stage drive motor 26 via servo amplifiers 23 and 24. Thus, when the distance between the target coordinate data and the current position is larger than the fine movement range (for example, 0.02 (■)), the X stage 3 and the X stage 2 first move as shown in period Tl in FIG. , after driving the X stage 3 and the X stage 2 in the high speed mode based on the trapezoidal speed pattern, when entering the fine movement range, the X stage 3 and the X stage 2 are driven in the fine movement mode based on the triangular speed pattern as shown in period T2. Drive the X stage 2.

In the case of Figure 8, the high-speed movement mode is from a stopped state with a speed of 0 to a maximum constant speed of 10 with an acceleration of 1000 (kaku/sec).
After rising to 0 (謹/see) and moving at this maximum constant speed, it falls to a stopped state with a speed of O with an acceleration of -1000 C/sec. In a triangular speed pattern where there is no time for fast movement, the speed pattern allows movement by approximately 10 degrees, and is designed to push the object into the micro-movement range.

In the subsequent fine movement mode, the data processing device 1
1 immediately changes the maximum speed from the state of speed O to 0°4 (sm/
After starting up to a speed of 0 (see), the speed pattern data is sent such that the speed falls from the maximum speed to a stopped state of a speed of O at an acceleration of -4 [r/sec"]. In this way, the X stage 3 and the X stage 2 This means that the robot can move by a movement path of 90.02 [11 minutes] corresponding to the area indicated by the symbol S2 during the fine movement movement mode.

In this way, the target position of X stage 3 and X stage 2 will be within the fine movement range, that is, 0.02
(■) If it is farther away, the current position is driven into the fine movement range by first moving at high speed in the high speed movement mode, and then it is stopped at the target position with high precision in the fine movement mode.

[Problem to be solved by the invention]

When using a conventional laser processing device with such a configuration,
The distance between each of the fuse groups FVI to FV4 to be cut is within the fine movement range of 0.02 (m) (-20 [μm)
) (for example, in the case of 10 (μm)),
When cutting successive fuses, the eighth
After moving and stopping the X and X stages 3 and 2 in the fine movement mode shown in the figure, the work of cutting the fuses is repeated, so the time required to cut all the fuses FVI to FV4 is long. As a result, there is a problem that the throughput of the laser processing apparatus 1 cannot be sufficiently improved.

For example, fuse FV2 of the row decoder section ROWI and fuse FV4 (FV
4A, FV4B) are set in the relationship shown in FIG.
When the cutting fuse is sequentially and intermittently cut by specifying 13 discretely scattered cutting points P, , P, ...pus according to the cutting fuse coordinate data DATA, the cutting point Pt'=
The fine movement range is 0.02 (
m), the data processing device 11 moves the X stage 3 and/or the X stage 2 to the cutting point P, using both the high speed movement mode and the fine movement mode in FIG.
, P, , Pl, and P4, and processing is performed using the laser beam LB in the stopped state.

Also, cutting positions P4 to P5, P, for fuse FV4,
~Pt, Pv~Pa, Pa~Pw, P++~pH is larger than the microtremor range of 0.02 (rising), so in this case also the 8th
The X stage 3 and the X stage 2 are stopped moving using both the high speed movement mode and the fine movement mode shown in the figure.

On the other hand, the cutting point Ps””Pi, P*~P1゜, Pl
. ~P8, the distance of p+x~pus is the fine movement distance 0.02 (
Since the distance is only 0.01 (■) smaller than [Ugly], the data processing device 11 moves the X stage 3 and Y stage 2 in the fine movement mode shown in FIG.

In this way, according to the conventional configuration, the movement of the X stage 3 and the Y stage 2 is controlled in a mode that always involves the fine movement mode, so all the cutting points P, ~P13
There is a problem in that the time required to perform the cutting process becomes long, and as a result, the throughput of the laser processing apparatus 1 cannot be practically improved.

The present invention has been made in consideration of the above points, and utilizes the fact that the X stage and Y stage can move with high precision to cut adjacent cutting points without stopping the X stage and/or Y stage. The purpose of this paper is to propose a laser processing device that can shorten the time required to cut all cutting points.

[Means to solve problems]

In order to solve the above-mentioned problems, the present invention detects a group of machining points arranged in a straight line or creates them by changing the order, and calculates the distance between two adjacent points. When the distance between two points is smaller than a predetermined amount, instead of stopping the relative movement of the beam and the workpiece at each processing point for positioning,
Each axis (or only the l-axis) is controlled to be sequentially machined (on-the-fly machining) while driving each axis continuously at a very low speed.

[For production]

In the present invention, when processing points are arranged adjacent to each other in a straight line at a fixed interval or less, a laser beam (actually, a laser beam is not emitted, so it is a virtual beam) is emitted by a laser beam scanning mechanism. A laser beam (referred to as a laser beam for simplicity) is scanned over the processing point at a very low speed, and instead of positioning the laser beam one point at a time, processing is performed while scanning the beam continuously (on-the-fly processing). Machining can be performed with a high throughput by moving between processing points at high speed and controlling the machine by emitting a laser after positioning.

〔Example〕

FIG. 1 shows a first embodiment of the present invention. In FIG. 1, a laser processing device 1 receives input defective data BAD to a cutting order control device 31 constituted by a computer, and then cuts between successive cutting points. When the distance is smaller than a predetermined value, the processing order of the cutting points is changed and the X scanner 1 is moved at a slow speed.
01 or Y scanner 102 is sent to the data processing device 11.

On the other hand, if the distance between the cutting points sequentially specified by the defective data BAD is longer than the predetermined switching limit value, the defective data BAD is directly input to the data processing device 11 as the cutting point data CUT. The scanner will be controlled by the positioning mode.

Cutting order control bag here! 31 selects the slow speed mode, the cutting order control device 31 selects one of the X-axis and Y-axis designation data, that is, the 7-wheel (or With the data fixed, the other side, that is, the X axis (
The X scanner 101 (or the Y scanner 1o2) is driven at a very slow speed by sequentially changing the coordinate data of the X scanner 101 (or the Y scanner 1o2). Coordinate data from the data processing device 11 is input to the X position setting register 12 and Y position setting register 13, and the contents of the X position register 16 and Y position register are determined from the position signal from the scanner indicating the current laser beam position. and the comparators 18 and 19, and when the two match, a trigger signal TRI is output from the AND circuit 20, which triggers the laser beam generation source 6 to generate the laser beam LB.
is guided to a predetermined position on the wafer 5 and processed.
If one axis in the scanning direction is fixed (for example, Y axis)
, the coincidence detection signal COMY remains output, and a trigger signal is sent to the laser at the moment COMX is output from the comparator in the X direction.

FIG. 2 shows how it is actually processed. FIG. 2 is a schematic diagram of a fuse section of a redundant circuit that has come to be used in semiconductor memory ICs in recent years. Partial defects due to dust etc. on semiconductor memory reduce yield, but redundant circuit technology involves preparing a spare circuit with a capacity other than the desired capacity in advance, and if there is a defective part on the main circuit side, it can be isolated. It has already been explained that defective chips can be made good by reconnecting them to the spare circuit side.When reconnecting the 0 circuit, the fuse provided in the decoder section is cut by a laser beam based on the defective data. In FIG. 2, machining points P and -P13 are machined.

In the machining of P, , P, , and Ps, the intervals between the machining points are large, and positioning at each point finishes faster than machining in the slow mode, so the normal positioning mode is used. P4, Pl, P9, Pl. , pH are arranged in a straight line and the distance between the processing points is short, so the slow speed mode is used. The laser beam is scanned at a low speed in the X-axis direction while keeping the Y coordinate constant, and on-the-fly processing is performed. That is, Pn, Pl,
When each point Pn, Plo, and P is reached, a trigger signal is sent out and processing is performed. From pH PIm is moved using normal positioning mode and again in slow mode Pl3
,prx,P,,P,,P,are processed.

The defective data is not necessarily arranged in the same order as the above-mentioned machining order.The cutting order control device 31 groups data that are lined up in a straight line from the coordinates of the machining point, and determines the machining order by finding the optimal path. Then, it is determined whether to use the normal positioning mode or the slow mode based on the distance between the processing points in each group.

The movement range of the laser beam changes depending on the optical system, but
Generally, considering aberrations and the like, only a narrow portion of the entire wafer can be processed, so the XY stage 4 performs a step-and-repeat operation.

Although the processing method using a beam scanning device using a scanner has been described in FIG. 1, a similar processing method can also be performed using a near-motor-driven XY table type, in which near-motor drive is performed in the X-wheel and Y-axis directions, respectively.

Also, if the machining points are lined up in a straight line in any direction,
By simultaneously slightly moving the scanning mechanism in the direction and the scanning mechanism in the Y direction at a certain speed, the slow mode of linear movement in any direction can be realized.

[Effects of the Invention] As described above, according to the present invention, among the discretely scattered processing points, the laser beam is directed to the processing points that are lined up in a straight line and are spaced at a constant interval or less, on the straight line where the processing points are lined up. While controlling the laser beam at very low speed, the laser beam is intermittently turned on and off without stopping, and other processing points are moved at high speed and the laser beam is turned on and off after positioning. This enables machining of multiple machining points with high throughput and high positional accuracy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a laser processing apparatus according to the present invention, and FIG. 2 is a route diagram showing the structure of fuses formed on the semiconductor chip of FIG. 1 and the processing order and control method according to the present invention. , FIG. 3 is a route diagram showing the configuration and processing order of fuses used in the conventional configuration shown in FIG. 7, FIG. 4 is a plan view showing the configuration of the memory chip 1, and FIGS. 5 and 6 are FIG. 7 is a block diagram showing a conventional laser processing apparatus, and FIG. 8 is a curve diagram showing its acceleration command pattern. (Explanation of symbols of main parts) 1... Laser processing device, 4... XY stage, 5...
...Semiconductor wafer, 6...Laser beam generation source, 11
...data processing device, 31...cutting order control device,
101...X scanner, 102...Y scanner. Applicant Nippon Kogaku Kogyo Co., Ltd.

Claims (1)

[Claims] In a laser processing device that irradiates a laser beam to an arbitrary processing point of the processing object by relatively moving the processing object and the laser beam, Control is performed so that the laser beam is emitted at the processing point after positioning by moving relative to the scheduled irradiation point at high speed, and when multiple processing points are lined up on a straight line with a fixed interval or less, the scheduled irradiation point of the laser beam is After relatively moving at high speed on an extension of the straight line, the laser beam is moved relatively at low speed on the straight line, and when the scheduled laser beam irradiation point reaches the processing point, the laser beam is emitted without stopping the relative movement at low speed. A method for controlling a laser beam of a laser processing device, characterized in that the laser beam is controlled so as to