JPS596060B2 - Semiconductor device inspection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for testing the characteristics of semiconductor chips during the manufacturing process of semiconductor devices.

A semiconductor device manufactured through a predetermined process is finally inspected to see whether desired characteristics are obtained, and whether the device is good or bad is determined based on the inspection results. In conventional semiconductor device manufacturing, this type of inspection process was performed after wire bonding between the semiconductor chip and the lead frame was completed. On the other hand, when wire bonding a semiconductor chip and a lead frame, one end of the wire is first bonded to the semiconductor chip electrode mounted on the lead to form the first bond, and then either the lead frame or the capillary supplying the wire is bonded to the semiconductor chip electrode mounted on the lead. The other end of the wire is moved to the area where it should be bonded, and after the position adjustment, the other end of the wire is bonded to the other lead to form a second bond, and the electrical connection between the semiconductor chip and the lead terminal is established. A method of connecting was adopted. Moreover, the characteristics inspection of the semiconductor chip was performed after the above-mentioned wire bonding was completed. That is, in conventional semiconductor device manufacturing, the wire bonding process and the semiconductor chip characteristic testing process are performed in separate and independent processes, which has the drawback of increasing the number of man-hours and requiring time and effort. The present invention utilizes a period in which position adjustment is performed between a capillary and a lead for the second bonding when the second bonding is performed following the first bonding process in the wire bonding process. By performing characteristic tests on semiconductor chips, the efficiency of manufacturing semiconductor devices is improved compared to the conventional method.

Next, the present invention will be described with reference to a wire bonding process for light emitting diodes.

In the figure, 1 is a lead frame, which is formed from a metal plate by punching or the like.

The lead frame 1 includes a lead terminal 1a to which a semiconductor chip 2 is die-bonded, and a die-bonded semiconductor chip 2.
A pair of lead terminals lb are electrically connected to each other by a wire 3, and a plurality of pairs of lead terminals are integrally provided on the same metal plate in a repeating pattern. After the semiconductor chip 2 is die-bonded to the lead terminal 1a via a conductive paste, the lead frame 1 is set in a lead frame feeding mechanism of a wire bonding device.
At the bonding position of the wire bonding apparatus, an ITV camera 4 is installed via an optical system 5 to capture an image of the semiconductor chip 2 on the lead frame. The semiconductor chip 2 transported to the bonding position is illuminated by a light source provided in the optical system 5 and captured by an ITV camera, and the level of the formed video signal is determined by a signal processing circuit to recognize the electrode position on the chip. be done. The recognized electrode position information is provided to a lead frame feeder arrangement or capillary drive device for feeding the wire;
The tip of the wire for bonding is aligned with the electrode on the semiconductor chip. The aligned semiconductor chip 2 and wire 3 are bonded by pressing down the capillary 6, completing the first bonding. Next, the capillary 6 or the lead frame 1 is moved relative to each other in order to bond the other end of the wire 3 to the lead 1b side for a second time, but the semiconductor chip is simultaneously moved during the relative movement and the position adjustment period after the movement. 2 characteristic tests are performed. That is, since the wire 3 for voltage application has already been connected to the semiconductor chip 2 through the first bonding, a voltage is applied between the semiconductor chip 2 and the lead frame 1 via the wire 3, thereby operating the semiconductor chip. Various characteristics such as light emitting output, forward voltage, and reverse breakdown voltage are inspected, and the quality of the first bonding is determined as well as the electrical characteristics of the semiconductor chip 2. Particularly in the inspection of the light emitting output, the ITV camera 4 used for recognizing the electrodes of semiconductor chips is also used. The output of the semiconductor chip that emits light upon application of a voltage is taken into the ITV camera 4 and photoelectrically converted into an electrical signal at a level corresponding to the optical output.
After the electrical signal is A/D converted, it is periodically sampled with a sampling pulse to divide the light emitting surface into a grid pattern,
Light emission output information at each point within the light emitting surface is formed. The light emission output information is based on a preset slice level or the first
The data formed from the semiconductor chip surface during bonding is processed to distinguish it from the background, and the sum of the light emitting output is detected by adding the information obtained from each divided area regarding the light emitting output information after the processing. can do. The light output can be converted into brightness by calculating the correlation between the sum of the light emitting outputs and the brightness in advance. The test results of the semiconductor chip are stored in a memory in correspondence with the semiconductor chip number, and are used as information for determining whether the chip is good or bad. In the above embodiment, the image pickup device for wire bonding is also used to detect the chip light emission output. However, if the combination is not appropriate due to the positional relationship of the image pickup device and the capillary, etc., the chip output may be used. It is also possible to separately install a second imaging device near the bonding position for detection.

During the period when the characteristics of the semiconductor chip 2 are being tested,
The tip of the capillary 6 is aligned to face the other lead terminal 1b, and after the characteristic test is completed, the newly positioned capillary 6 is pressed down and the other end of the wire 3 is second bonded to the lead terminal 1b.

The first and second bonded lead frames 1 are transported by one pitch by the feeding mechanism, and the semiconductor chip die-bonded to the next lead pair is set at the bonding position, and the above operation is repeated. Although the above embodiment has been described using a process of wire bonding a light emitting diode as a semiconductor chip, the present invention can be similarly practiced with other semiconductor chips.

As described above, according to the present invention, a current is supplied to the semiconductor chip through the wire in the first bonding state, the semiconductor chip is put into test operation, the characteristics of the semiconductor chip are inspected, and the second bonding is performed after the characteristic inspection. This eliminates the need to re-set the lead frame each time in a separate process for testing the characteristics of semiconductor chips as in the past, making it possible to test the characteristics of semiconductor chips within a single wire bonding process. Since the process can be completed, it is possible to significantly save time and effort, and the imaging device and other peripheral equipment used during wire bonding can also be used for testing the characteristics of semiconductor chips.

Furthermore, efficiency can be improved by reducing the number of manufacturing steps for semiconductor devices.

[Brief explanation of drawings]

The figure is a schematic diagram of main parts for explaining the present invention. 1: lead frame, 2: semiconductor chip, 3: wire,
4: ITV camera, 6: Capillary.

Claims (1)

[Claims] 1. A method for inspecting a semiconductor device formed by first bonding one end of a wire to a semiconductor chip mounted on a lead, and then second bonding the other end of the wire to another lead. In the first bonding state, a current is supplied to the semiconductor chip through a wire to cause the semiconductor chip to perform a test operation to test the characteristics of the semiconductor chip, and after the characteristics test, the second bonding is performed. An inspection method for semiconductor devices.