JPS629724Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a laser marking device that uses a laser beam, and in particular, its purpose is to attach it to a prober device used for determining the acceptability of semiconductor integrated circuit chips and mark defective chips by laser processing. This invention relates to a laser marking device.

Normally, semiconductor integrated circuits are manufactured by forming a large number of elements or circuits on a single semiconductor wafer, which takes many steps and time. It is becoming expensive. In each chip (individual element or circuit), there are good products that achieve a predetermined performance and defective products that do not, and a process is required to inspect and separate them.

In this process, a probe (hereinafter referred to as a probe) is brought into contact with each electrode of the chip, and the electrical characteristics of the circuit are measured to determine pass/fail. Defective chips are marked on the surface, and defective chips are marked in the subsequent process. The chips are removed and only good chips are assembled and sent out as products. Therefore, it is necessary to avoid erroneously determining good and defective products or damaging the wafer in this process. Furthermore, the reproducibility (clarity,
size, location) are essential for automating the sorting process.

Traditionally, two methods have been used for this marking: ink and mechanical scratching.
There are problems such as erroneous determination of good and defective products due to ink scattering, inability to measure due to adhesion to the probe, mark errors due to ink clogging, and mark disappearance during the cleaning process. In the case of mechanical marks, wafers with hard surfaces are difficult to scratch and the marks are unclear, making it easy to make mistakes in sorting decisions in post-processing. Also, since mechanical pressure is applied to the wafers, there is a risk of damage. There are problems in that maintenance work is frequently required due to the short lifespan of the scribing needle.

As mentioned above, conventional marking methods had many inconveniences, but the laser beam marking method can mark without contacting the wafer, eliminating cracks on the wafer and easily marking the wafer regardless of the surface condition of the wafer. It has great effects on the manufacturing process, such as making a mark and making it easy to automate since a clear mark that never disappears can be made at a fixed position. Conventionally, this type of laser marking device consists of a prober device that is linked to an existing tester, a laser power supply section, a cooling section, a laser beam oscillation section, and a laser beam from this laser beam oscillation section that is applied to the semiconductor wafer chip that is the workpiece. It consists of a condensing optical system for condensing light. In such equipment, a wafer, which is a workpiece on which a large number of chips have been formed, is vacuum-adsorbed onto the table of a prober equipment, moved to a measurement point, and then the probe comes into contact with each electrode within the chip to measure the electrical circuit. Measure properties. If the measurement result is good, move on to the next chip and measure it. However, if the measurement result is determined to be defective, the prober device sends an electrical signal to the external signal input terminal of the laser power supply section and the laser beam is emitted. oscillates and irradiates a laser beam at a predetermined position on the chip using a condensing optical system to perform melting and mark the chip. However, the laser marking device with the above configuration requires the same number of laser power supply units, cooling units, laser beam oscillation units, and focusing optical systems for multiple prober devices, which occupies a considerable amount of floor space. I will do it.

Generally, work in semiconductor integrated circuit manufacturing factories is carried out in a place called a clean room, where the internal environment (temperature, humidity, dust, etc.) is maintained, but maintaining this environment requires equipment and maintenance costs. It's getting expensive. Therefore, compared to general work sites, it is more expensive per unit area, so it is desirable that the occupied floor space be kept to the minimum necessary. Furthermore, when multiple prober devices are linked to one tester, the tester does not send judgment results to each prober device at the same time, and the prober device itself cannot move unless it is linked to the tester. It is wasteful to have the same number of laser power supply units as prober devices that are always waiting for input of determination results. Semiconductor manufacturing equipment is generally expensive, and efficiency is increased by increasing operating time as much as possible, so equipment with long downtime (stopping and waiting time) ends up being expensive even if the price is low. .

Therefore, the purpose of this invention is to create an efficient low-speed laser that can effectively utilize the limited floor space without degrading the performance of conventional laser marking, and that shortens the input time of the laser power supply section. Our goal is to provide an affordable laser marking device.

In order to achieve this purpose, the laser marking device of the present invention includes a plurality of laser devices and an optical system that focuses the output light of each of these laser devices onto the surface of a semiconductor integrated circuit chip formed on a semiconductor wafer. A number of prober devices having the same number of laser devices as the laser devices each having a probe that contacts the chip, a tester for each prober device to determine the quality of the semiconductor wafer from the output of the probe and generating a defective judgment signal in the case of a defect, and a tester for each laser device. A plurality of input holding circuits are arranged in the tester and hold the defect judgment signal from the tester for a predetermined period of time, a plurality of AND circuits are supplied with the outputs of each of the input holding circuits as input signals, and the inputs of each AND circuit are sequentially input. The output of the laser power supply circuit is supplied only to the laser device corresponding to the decoder that generates the scanning gate signal, one laser power supply circuit, and the input holding circuit that is supplied with the defective judgment signal according to the output of the AND circuit. It has a circuit.

The present invention will be explained below with reference to one embodiment.

FIG. 1 shows one embodiment of the present invention, and is a schematic diagram when it is combined with four prober devices connected to one tester. The wafer 9a, which is the workpiece, is vacuum-adsorbed on the wafer fixing table 10a of the prober device 2a, and the probes 11a, the number of which is the number of electrodes, can come into contact with each power source of the chip. The laser beam condensing optical system 3a is arranged and fixed on the prober device 2a so that the laser beam is condensed and irradiated to the position on the chip to be marked.
It is connected to the laser beam oscillation section 7a through an optical fiber 8a. The main laser power supply section 4, signal distribution circuit 5, and cooler 6 are housed in one housing and installed outside the prober devices 2a to 2d. The pass/fail judgment signal from the tester 1 is sent to each prober device 2a~
The signal is input to the signal distribution circuit section 5 via 2d.

In the above configuration, first, a probe 11a is attached to each electrode of a chip formed in large numbers on a wafer.
is in contact with the tester 1 in conjunction with the prober device 2a.
The characteristics of the circuit are measured, and if the chip is judged to be good, the circuit moves to the next chip and the next chip is measured. If it is determined to be defective, a marking request signal is sent from the prober device 2a to the signal distribution circuit 5. The signal distribution circuit 5 receives this signal, operates the main laser power supply section 4 after a certain timing, and oscillates a laser beam from the laser beam oscillation section 7a corresponding to the prober device 2a that generated the marking request signal. The oscillated laser beam is transmitted through the optical fiber 8a and is focused and irradiated onto a predetermined position on the chip by the condensing optical system 3a to mark a mark. Prober 2b,
Probers 2c and 2d also perform the same operation as the above-mentioned prober 2a. FIG. 2 is a block diagram of the signal distribution circuit 5. Marking request signals sent independently from each prober device are sent to input circuits 12a to 12d.
After the waveform is shaped through the flip-flops 13a to 13d, each of the flip-flops 13a to 13d is set. On the other hand, the clock pulse generating circuit 19 generates a signal serving as a timing reference, and its output is applied to the counter 18, and further distributed sequentially by the decoder 17 to scan and check whether there is an output from each flip-flop. That is, the decoder 17
The output of 8 is distributed in a time division manner to AND circuit 14.
A scanning signal is sequentially output to a, 14b, 14c, and 14d. If there is an output to the flip-flop (hereinafter referred to as F/F) 13a (if a marking request is made), the output of the decoder 17 and
After a match is made in the circuit 14a and the signal is delayed in the delay circuit 15a, the delay trigger pulse generation circuit 16a and the charging circuit 22 inside the main laser power supply section 4 are connected.
Output to. Also, return to this signal F/F13a,
A reset is performed to return the F/F 13a to the input waiting state. Below, F/F13a → 13a → 13c → 13d → 1 sequentially for each clock cycle
3a... Repeat the scanning, and each F/F13a-1
If there is an output in 3d, the process described above is performed on it, and if there is no output, the process moves to the next step. Here, the clock period (Tc) is Tc≦Tt/, where the pass/fail judgment time (inspection time) of the tester is Tt, and the number of connected prober devices is Np.
Must be set to Np. FIG. 3 is a block diagram of the inside of the main laser power supply section 4. As shown in FIG. Signal distribution circuit 5
Therefore, the outputs of the four delay circuits 15a to 15d are
It is sent out through the OR circuit 20. Charging circuit 2
2 starts charging immediately regardless of the output of any of the delay circuits 15a to 15d. The outputs 15a to 15d of the delay circuits corresponding to the input circuits 12a to 12d receiving the marking request signal are delayed by delay trigger circuits 16a to 16d, and then sent to and connected to the corresponding trigger circuits 23a to 23d. Laser light is oscillated by generating excitation lamps inside the laser light oscillating units 7a to 7d. Here, if the ratio of the operating time and stop time of the laser power supply unit is P when there is only one conventional prober device and one laser power supply unit, then if the number of prober devices increases by N, then
The ratio will be improved to P/N.

As explained above, according to the present invention, only one rectification and charging circuit is required for the laser power supply section, which accounts for a large proportion of the volume and cost, and the operating efficiency of the laser power supply itself can be increased, compared to conventional methods. As a result, a compact and low-cost laser marking device can be realized.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a laser marking apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram of a signal distribution circuit, and FIG. 3 is a block diagram of a main laser power supply section. 1... Tester, 2a to 2d... Prober device,
3a-d...Condensing optical system, 4...Main laser power supply section, 5...Signal distribution circuit, 6...Cooler, 7a-
7d...Laser beam oscillation unit, 8a-8d...Optical fiber, 9a-9d...Wafer, 10a-10d...
...Wafer fixing table, 11a-11d...Probe, 12a-12d...Input circuit, 15a-1
5d...Delay circuit, 16a-16d...Delay trigger pulse generation circuit, 17...Decoder, 18...
Counter, 19...Clock pulse generation circuit, 2
1... Rectifier circuit, 22... Charging circuit, 23a-2
3d...Trigger circuit.

Claims (1)

[Scope of utility model registration request] a plurality of laser devices, an optical system for condensing output light from the laser devices onto the surface of a semiconductor integrated circuit chip formed on a semiconductor wafer, and a number of prober devices equal to the number of the laser devices; a tester that determines the quality of the semiconductor wafer from the output of the probe for each of the prober devices and generates a failure determination signal in the case of failure; and a tester that is arranged for each of the laser devices and holds the failure determination signal for a predetermined period of time. a plurality of input holding circuits, a plurality of AND circuits to which respective outputs of the input holding circuits are supplied as input signals, a decoder that generates a gate signal to sequentially scan the inputs of the AND circuits, and one laser. A laser marking device comprising: a power supply circuit; and a circuit that supplies the output of the laser power supply circuit only to the laser device corresponding to the input holding circuit to which the defect determination signal is supplied in accordance with the output of the AND circuit.