METHOD AND ARRANGEMENT FOR POSITIONING A PROBE CARD

Abstract

A method for perpendicular positioning of a probe card relative to a test substrate, includes storing a separation position approached in a first positioning step as a distance between the needle tips of the probe card and the substrate, storing a contact position approached in a second positioning step until the probe card contacts the substrate, and displaying an image of the needle tips. For avoiding erroneous operation after a probe card has been changed, when imaging the needle tips, the stored contact position is imaged and is changed until presentation of this contact position corresponds to actual height of the tips appropriate for the respective probe card and this setting is then stored as a new contact position. A display device presents the needle tips and the stored contact position and is connected to a memory, a recording device and an input device which changes the contact position.

Description

BACKGROUND ART

The invention relates to a method for positioning a probe card with probe needles, which have needle tips, relative to the surface of a substrate to be tested in a direction perpendicular to the surface of the substrate. In this case, a first position of the needle tips relative to the surface of the substrate is measured and stored as a separation position in such a manner that it is approached in a first positioning step, which does not measure the distance between the needle tips and the surface of the substrate, so as to produce a distance between the needle tips and the surface of the substrate. Furthermore, a second position of the needle tips relative to the surface of the substrate is measured and stored as a contact position in such a manner that it is approached in a second positioning step, which does not measure the distance between the needle tips and the surface of the substrate, until the needle tips make contact with the surface of the substrate. An image of the needle tips is recorded along at least one horizontal imaging direction, which is essentially parallel to the surface of the substrate, and is displayed.

The invention also relates to an arrangement for positioning a probe card with probe needles, which have needle tips and are arranged on the probe card such that they are oriented in position. In this case, the arrangement has a substrate holder, a setting device for adjusting the substrate holder relative to the probe card, and a recording device whose recording axis is directed at the probe needles and essentially parallel to the substrate surface. In this case, the setting device is provided with a drive device which is provided with a memory that stores a contact position and a separation position.

Substrates having electrically active components, for example semiconductor components, have so-called contact pads which are used to make contact from the outside by means of probe needles. Signals can therefore be applied to these semiconductor components from the outside and the reactions of the latter to these signals can be determined. It thus becomes possible to test these substrates. So-called probers are provided for such a test.

Probe needles of probers are fastened either to probe holders or to probe cards. When probe holders are used, the probe holders are positioned on a probe holder plate in such a manner that the needle tips of the probe needles are opposite the contact pads in accordance with the pattern assumed by the contact pads.

When probe cards are used, the probe needles are fastened to just these probe cards in such a manner that the needle tips of the probe needles are likewise opposite the contact pads in the form of the patterns assumed by these contact pads.

In order to observe the probe needles when contact is being made with the contact pads, DE 103 29 792.8 describes an observation device having an observation axis such that the observation axis runs in the gap between the free surface of the wafer and the holding apparatus or apparatuses.

These observation devices can be used to subject the probe needles to precise observation. For example, precisely the extent of overdrive achieved can thus be determined and the movement in the Z direction can be set when an extent has been defined.

In this case, it is expedient for the observation axis to run in an essentially horizontal manner and parallel to the free surface of the wafer. As a result, the holding apparatuses of the components or other components do not obstruct the view of the probe needles.

Whereas the relative distance between the needle tips of the probe needles and the surface of the substrate to be tested can be set and is consequently dependent on the setting device which sets this distance, for example a substrate clamping apparatus which carries out a movement in a direction perpendicular to the semiconductor surface, the absolute height of the needle tips, that is to say the distance between the needle tips and the installation position of the probe holder, for example a probe holder plate, is dependent on the installation or the geometrical configuration of the probe holder.

The substrates are normally tested in a substrate assembly, for example in a semiconductor wafer, on which a plurality of chips are arranged as substrates. In this case, a chip is positioned relative to the needle tips in the lateral direction in such a manner that the needle tips come to rest above the contact pads. Contact is not yet made in this case since, for the purpose of moving the chips relative to the needle tips, it is necessary to set a distance between the needle tips and the surface of the substrate in order to avoid the needle tips scratching the surface of the substrate. Only in the post-position is the distance between the needle tips and the surface of the substrate reduced to such an extent that the needle tips on the contact pads carry out a slight scratch, that is to say a slight lateral movement, on the contact pad.

After testing, the next substrate is then approached. In this case, the distance between the needle tips and the surface of the substrate is set again, the lateral movement is carried out in order to reach the next test position, and contact is made again.

In order to increase the speed, particularly during automatic testing, the two vertical positions, that is to say the first vertical position which is referred to as the “separation position” and the second vertical position which is referred to as the “contact position”, are stored and are read out during positioning and are set using a setting device.

Since there are no precise details of the exact absolute height of the probe needles, these two stored positions no longer correspond to the actual conditions after the probe card has been changed. If work is then continued with the stored positions after the probe card has been changed, this may result in contact being made erroneously, in the needle tips grinding the surface of the substrates in the event of a change in position or in an excessive contact pressure and thus in the destruction of the substrate or the substrate assembly.

BRIEF SUMMARY OF THE INVENTION

The object of the invention is now to ensure that, after a probe card has been changed, the separation position and the contact position can be adapted to the probe card in a simple manner in order to thus avoid erroneous operation.

This object is achieved with a method according to Claims 1 to 9 and with an arrangement according to Claims 10 to 14.

The invention shall be explained in more detail below using an exemplary embodiment.

BRIEF DESCRIPTION OF DRAWING FIGURES

FIG. 1 illustrates an original image on a display;

FIG. 2 depicts a displayed image of a newly installed probe card;

FIG. 3 depicts a displayed image with a repositioned probe horizon;

FIG. 4 depicts a displayed image of the repositioned probe horizon at a height of the needle tips;

FIG. 5 is a perspective view of a probe card in a probe card holder with a sliding piece and a sensor element;

FIG. 6 is an enlarged view of a portion of FIG. 5 showing the sliding piece locked in position; and

FIG. 7 is an enlarged view of a portion of FIG. 5 showing the sliding piece displaced.

DETAILED DESCRIPTION

As illustrated in FIG. 1, a recording device (not illustrated in any more detail) presents the probe needles 1 on a display device 2. In this case, the needle tips 3 are also concomitantly imaged. A so-called probe horizon 4 which is generated by means of computation is also imaged on the display device 2. This probe horizon 4 represents the absolute height of the needle tips 3 and is stored in a memory which is likewise not illustrated in any more detail.

FIG. 2 now illustrates the state which occurs after a new probe card has been installed. In the case of the newly installed probe card, the needle tips 3 are lower, due to the manufacturing technology, than in the case of the probe card illustrated in FIG. 1. The stored probe horizon 4 which is equal to the probe horizon 4 in FIG. 1 is thus above the needle tips 3.

The probe horizon 4 is then used to calculate, by means of computation, both the contact position in which the needle tips 3 are in contact with the contact pads of the substrate and the separation position in which the probe needles 1 or rather the needle tips 3 are at a distance from the surface of the substrate, and the setting device is set correspondingly for the substrate holder. If the contact position now no longer corresponds to the actual height of the needle tips 3, this may result in considerable impairment and may go as far as destruction of the substrate.

As illustrated in FIG. 3, input means (not illustrated in any more detail) can now be used to set the position of the probe horizon 4 in any desired position relative to the needle tips 3. It goes without saying that it is expedient to set the probe horizon 4 at the height of the needle tips 3 again, as illustrated in FIG. 4. The contact position which corresponds to the newly inserted probe card is now also calculated from the setting of the probe horizon 4 in this position.

It is very expedient, in particular when the ratio of the stored probe horizon 4 to the actual position of the needle tips 3 is to be presented in order to thus correct the values which are stored and used for positioning, if the probe card has been changed.

An arrangement as illustrated in FIGS. 5 to 8 is used for this task.

According to FIG. 5, a probe card 5 which is arranged in a probe card holder 6 is locked using a sliding piece 7.

A sensor piece 8 which is statically connected to the probe card holder is arranged on the sliding piece 7 in the immediate vicinity.

A pressure line 9 which is connected to a vacuum or compressed air source (not illustrated in any more detail) and opens in an opening 10 is arranged in the sensor piece 8. As illustrated in FIG. 6, the opening 10 is closed when the sliding piece 7 is locked.

If the probe card 5 is intended to be removed, it is necessary to displace the sliding piece 8 to such an extent that the probe card 5 can be removed and a new one can be inserted. The opening 10 is thus compulsorily freed. This opening thus generates a pressure difference in the pressure line, which can be measured and detects when the probe card 5 is changed.

Detection of such a change can also be used, inter alia, to give rise to the display shown in FIGS. 1 to 4 and the associated correction of the stored contact position.

Claims

1. Method for positioning a probe card with probe needles, which needles have needle tips, relative to a surface of a substrate to be tested in a direction perpendicular to the surface of the substrate, a first position of the needle tips relative to the surface of the substrate being measured and stored as a separation position in such a manner that the separation point is approached in a first positioning step, which step does not measure the distance between the needle tips and the surface of the substrate, so as to produce a distance between the needle tips and the surface of the substrate, a second position of the needle tips relative to the surface of the substrate being measured and stored as a contact position in such a manner that the contact position is approached in a second positioning step, which second step does not measure the distance between the needle tips and the surface of the substrate, until the needle tips make contact with the surface of the substrate, an image of the needle tips being recorded along at least one horizontal imaging direction, which direction is essentially parallel to the surface of the substrate, and being displayed, and, when imaging the needle tips, the stored contact position is imaged or an absolute height of the needle tips which corresponds to the stored contact position is imaged, the imaged contact position or the imaged absolute height of the needle tips is changed until presentation of these positions corresponds to a height of the needle tips which is appropriate for the respective probe card or corresponds to an appropriate height of the contact position and this contact position which has been set is then stored as a new contact position or the corresponding contact position is calculated from set height of the contacts and is stored.

2. Method according to claim 1, wherein the height of the separation position is calculated from the stored contact position or is calculated using the stored height of the needle tips over a predefined distance and is stored.

3. Method according to claim 1, wherein, when imaging the needle tips, the stored separation position is imaged, and the stored separation position is changed until the presentation of these positions corresponds to the height of the separation position which is appropriate for the respective probe card and this separation position which has been set is then stored as a new separation position.

4. Method according to claim 1, wherein removal of the probe card from a probe card holder is detected and the stored contact position is presented when removal has been determined.

5. Method according to claim 4, wherein removal of the probe card is detected if a distance between the probe card and the probe card holder is exceeded.

6. Method according to claim 1, wherein position of the needle tips is electronically determined from the imaging of the needle tips and is stored.

7. Method according to claim 6, wherein the contact position is calculated from the stored position of the needle tips and is stored.

8. Method according to claim 7, wherein the separation position is calculated from the stored position of the needle tips or from the calculated contact position and is stored.

9. Method according to claim 4, wherein, when removal is detected, an error signal is output if a defined difference between the position of the needle tips and the stored contact position is exceeded.

10. Arrangement for positioning a probe card with probe needles, which needles have needle tips and are arranged on the probe card such that the needles are oriented in position, comprising a substrate holder, a setting device for adjusting the substrate holder relative to the probe card, a recording device with a recording axis directed at the probe needles and essentially parallel to a surface of the substrate, the setting device including a drive device having a memory that stores a contact position and a separation position, and a display device that presents the needle tips and the stored contact position and is connected to the memory and to a recording device and has an input means which changes the contact position.

11. Arrangement according to claim 10, further comprising means which detects removal of the probe card and is connected to the recording device.

12. Arrangement according to claim 11, further comprising means which detects distance between the probe card and a probe card holder.

13. Arrangement according to claim 11, wherein an opening which is connected to a compressed air source or to a vacuum source by a pressure line is arranged in the probe card holder, said opening being closed when the probe card is inserted in the probe card holder and being open when the probe card has been removed, and the pressure line is connected to a pressure measuring device which detects a pressure difference in the pressure line and, is connected to an evaluation unit which determines a pressure difference.

14. Arrangement according to claim 13, wherein the probe card holder is provided with a sliding piece which locks the probe card and has a position which unlocks the probe card and in which the opening is open and a position which locks the probe card and in which the opening is closed.