JPS62136041A - Wafer prober - Google Patents

Abstract

PURPOSE:To avoid time loss caused by inker defect, by providing a detector, which issues signals showing a mark size, a mark size discriminator, and a controller. CONSTITUTION:When an integrated circuit chip of wafer 1 is tested and judged as defective, a defect mark is impressed by an inker 4 which is actuated with an inker driver 8. When the defect mark is impressed, a mark size discriminat ing unit 7 detects the size of the defect mark during a drive of the inker 4. Then, a defect mark-detecting signal is outputted to a controller 9 when the size becomes optimum, to correspond to the signal and make the controller 9 stop the drive of the inker driver 8. The mark size discriminating unit 7 integrates several numbers of horizontal video signals in the detect mark parts from a TV camera 5 to detect the size of the defect mark put by the inker. Thus, a time loss caused by inker defect can be avoided.

Description

[Detailed Description of the Invention] [Field of the Invention] The present invention relates to a wafer prober used in an inspection device for semiconductor wafers on which AM circuit chips are baked, and more specifically, a wafer prober for marking defective integrated circuit chips. This relates to improvements in equipment for

[Background of the Invention] Conventional wafer probers do not have a function to monitor the results of inker driving, and therefore, if there is a failure such as malfunction of the inker or running out of ink during the test, it is possible to detect a defective integrated circuit chip. It was not possible to mark the product as defective, and it was sometimes mistaken as a non-defective product in a later process.

For this reason, there was an inconvenience that many defective products were found during testing after packaging was completed.

Furthermore, even if the inker does not malfunction or run out of ink, the large dents of the defective marks often vary due to the curing of the ink over time, and this causes problems in subsequent processing.
(For example, in die mounters), this caused erroneous detection of good and bad chips.

Recently, in order to improve this point, a wafer prober has been proposed in which a sensor for detecting defective marks is provided at a position separate from the inker. However, this method has the following drawbacks because defective marks are detected after all chips on the wafer have been tested and defective integrated circuit chips have been inked.

1) Even if an inker defect occurred during the test of an integrated circuit chip, this defect could not be detected until all chips were tested. Further, in this case, it is necessary to retest, but since retesting would damage the bonding pads, there was a risk that even a good integrated circuit chip would be turned into 6 defective products.

2) Since there is no function to keep the size of defective marks constant,
In subsequent steps, a good chip may be mistaken as a defective chip, or a defective chip may be mistaken as a good chip.

3) After testing all chips, defective marks were detected at a different location, resulting in a drop in throughput.

4) A memory or the like was required to store the location of the defective chip.

[Object of the Invention] An object of the present invention is to solve the problems of the prior art by providing a wafer prober that always maintains a constant size of defective marks caused by an inker.

The purpose of this is to provide a wafer prober with the function of detecting the size of a defective mark made by an inker during inker driving and stopping inker driving when the size reaches an appropriate size, according to the present invention. This is achieved by That is, according to the present invention, the wafer prober includes a detection device that detects the mark placed on the wafer to be inspected by the inker and generates a signal representing the size of the mark, and when the mark has reached the appropriate size based on the signal from the detection device. The present invention includes a mark size discriminator that determines the mark size and generates a signal at that point, and a controller that stops the operation of the inker driver in response to the signal from the discriminator.

[Example] FIG. 1 shows an example of the present invention. In FIG.
3 a probe card used to make electrical contact between the integrated circuit chips on the wafer and a tester (not shown); 4 an inker for marking defective chips on defective chips; 5 is a TV camera for detecting defective marks, 6 is a TV monitor for observing defective marks detected by TV camera 5, and 7 is V
A mark size determination unit outputs a defective mark detection signal when the defective mark detected by the camera has an optimal size; 8 is an inker driver that drives the inker 4; 9 is a driver for driving the inker driver 8; This is a controller that stops driving the inker driver 8 based on a defective mark detection signal from the mark size discrimination unit 7.

Explain the operation. The integrated circuit chips on the wafer 1 are electrically connected to the probe card 3 by the movement of the wafer chuck 2 in the XY direction and in the vertical direction. After this, the tester (
(not shown) performs a test on this integrated circuit chip, and if the chip is defective, the inker driver 8
A defective mark is placed by the inker 4 driven by. When placing this defective mark, the mark size discrimination unit 7 detects the size of the defective mark while the inker 4 is being driven, and outputs a defective mark detection signal to the controller 9 when the defective mark has reached the optimum size. In response to this signal, the controller 9 stops driving the inker driver 8.

The mark size determination unit 7 integrates several of the horizontal video signals of the defective mark portion from the TV camera 5, and detects the black level in this horizontal video signal, that is, the size of the defective mark made by the inker. .

FIG. 2 shows another embodiment of the invention. As in the embodiment shown in FIG. 1, 1 is a wafer, 2 is a wafer chuck, 3 is a probe card, and 4 is an inker. 8 is an inker driver that drives the inker 4, 9 is a controller, 10 is a highly directional light emitting diode, 11 is a half mirror, 112 is a photosensor, 13 is a photosensor, and the defect mark by the inker is optimized depending on the level of incoming light. This is a comparator to determine whether the

The operation is to irradiate the mark with light from the light emitting diode 10,
The embodiment is the same as the embodiment shown in FIG. 1 except that the reflected light is detected by the photosensor 12, and the explanation thereof will be omitted. The embodiment shown in FIG. 2 has a simpler configuration and is smaller than the embodiment shown in FIG. In the prober, the inker drive stop timing is controlled so that it is when the defective mark reaches the optimal size, but this inker drive does not have to be continuous, and can be performed intermittently several times. good. In that case, the number of times of driving must be adjusted.

If the size of the defective mark is so small that the tip of the inker cannot detect the defective mark, intermittent driving may be more effective.

Furthermore, a one-dimensional line sensor may be used as a means for detecting defective marks.

[Effects of the Invention] As explained above, the following effects can be obtained by detecting the size of a defective mark when driving the inker and controlling the size to be optimal.

1) If an inker defect occurs during the test 1 of the integrated circuit chip, this defective state can be detected immediately, and time loss due to the inker defect can be avoided.

Further, there is no need for retesting, and damage to good integrated circuit chips due to retesting can be avoided.

2) Since the size of the defective mark can be kept constant, defective marks can be detected reliably in subsequent steps.

3) Since the inker drive and detection are performed at the test position, there is less time loss compared to the case where the detection is performed at a different position.

4) Since the inker drive and detection are performed at the test position, there is no need for a memory or the like to memorize the position of the defective integrated circuit chip.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a first embodiment of the invention. FIG. 2 is a schematic illustration of a second embodiment of the invention. In the attached figure, 1 is a wafer, 2 is a wafer chuck, 3 is a probe card, 4 is an inker, 5 is a TV camera, 6 is a TV monitor, 7 is a mark size discrimination unit, 8 is an inker driver, 9 is a controller, 10 is a light emitting diode, 11 is a half mirror, 112 is a photosensor, 13
is a comparator.

Claims (1)

[Claims] 1. An inker, an inker driver for driving this inker, a detection device that detects a mark that the inker makes on a sample wafer and generates a signal representing the size of the mark, and a signal from this detection device. A mark size discrimination device that determines when the mark has reached an appropriate size based on a signal and generates the signal, and a controller that stops the operation of the inker driver in response to the signal from the discrimination device. A wafer prober featuring: 2. The wafer prober according to claim 1, wherein the detection device is a TV camera. 3. The detection device includes a light emitting diode, a photosensor, and projects light from the light emitting diode onto the wafer to be inspected;
The wafer prober according to claim 1, further comprising a half mirror that projects reflected light from the wafer onto the photosensor. 4. The wafer prober according to claim 1, wherein the detection device includes a one-dimensional line sensor. 5. The wafer prober according to claim 1, wherein the inker driver is a driver that drives the inker intermittently.