JPH0258846A - Automatic alignment of probe card - Google Patents

Abstract

PURPOSE:To facilitate the alignment with high precision corresponding to any collected data by a method wherein the overlapped state in the central part of a target window on a chip with the end part of a target pointer on a probe card corresponding to the central part is automatically recognized as the fluctuation of the state of contrast. CONSTITUTION:The positional relation between the central part 131 of a target window and the end part 231 of a target pointer can be detected by the fluctuation in the state of contrast i.e., when the positional relation is shifted, the target window seen from the central part thereof becomes asymmetrical while when the positonal relation is normal, said target window becomes symmetrical. Then, the X, Y directional positions of a chuck loaded with a wafer or a card thetais automatically corrected from the detected results. Through these procedures, the proper alignment of probe card with a chip can be performed with high precision.

Description

[Detailed Description of the Invention] [Summary] A method for automatically aligning a chip in a wafer state and a probe card used for measuring the chip, which automatically achieves alignment of the probe card with high precision and high speed. For the purpose of On the probe card having 1 pair of target windows, 1 pair of probes are formed, each having a reflectivity equivalent to that of the periphery of the target window and having a similar shape to the center of the target window, in correspondence with each of the 1 pairs of target windows. A pair of target needles are arranged, and alignment of the chip and the probe card is achieved by automatically recognizing each positional relationship between the pair of target windows and the corresponding pair of target needles. It is configured as follows.

[Industrial application field]

The present invention relates to a method for automatically aligning a semiconductor device in a wafer state (that is, a chip in a wafer state) and a probe card used for measuring the chip.

[Conventional technology]

Traditionally, when measuring this type of chip, a probe card with probe needles corresponding to each bonding band of the chip is used, and each bonding band and its corresponding probe needle are electrically and mechanically positioned at optimal positions. is required to be in good contact with the For this purpose, it is necessary to align the relative positions of the probe card and the chip to be measured with high precision.

FIG. 6 shows a schematic configuration of a prober for aligning the probe card in the prior art, in which a probe card 21 having a probe needle 22 is integrally constructed with a card pogo pin 25 and a performance port 26. is fixed to the prober housing 4. The probe card 21 is electrically and mechanically coupled to the tester head 31 via tester pogo pins 32, but there is some play in the tester pogo pins 32, which allows the probe card (the The probe card (from the probe card to the performance board) is rotatable within a predetermined angular range in its horizontal plane, and the degree of freedom of the probe card can therefore be adjusted by only the so-called card θ.

On the other hand, the wafer 11 is placed on the chuck 51 and fixed by suction using a vacuum. The degree of freedom of the chuck 51 is X
, Y, and Z directions and by rotation (chuck θ) in the horizontal plane. Note that movement from a given chip on the wafer to an adjacent chip is performed by moving the chuck in the X and Y directions by the size of the chip (along the scribe line provided on the acid wafer), and the probe Contact between the needle and each bonding band is made by moving the chuck in the Z direction. Furthermore, the scribe line provided on the wafer and the X of the chamfer are aligned in parallel to each other.

Parallel alignment with the Y movement direction) is performed by rotating the chuck (adjusting the chuck θ). And the probe card 21 for the chip to be measured on the wafer (11).
Parallel alignment (positioning) is performed by rotating the probe car F side (adjusting the card θ), thereby adjusting the position of the probe needle with respect to each pad. In this case, when aligning the probe card, the measuring operator manually (or by using a motor or the like) manually (or by using a motor, etc.) align the center of the corresponding probe needle with the center of each bonding band by visual inspection.

[Problem to be solved by the invention]

However, in the probe card positioning method according to the above-mentioned prior art, the visual range becomes wider due to the multi-pad number of the chip, and the visibility of the center of each bonding band deteriorates, making it extremely difficult to perform proper visual inspection.

Therefore, with the conventional probe card positioning method described above, it is very difficult to improve the positioning accuracy, and the time required for positioning is extremely long.

The present invention was made to solve such problems,
The positioning of the probe card can be automatically achieved with high precision and high speed.

[Means to solve the problem]

In order to solve the above problems, in the present invention, a pair of target windows are arranged on a chip of a semiconductor wafer, and each target window on the chip is arranged such that the peripheral part thereof has a different reflectivity from the central part. On the probe card having probe needles corresponding to the bands, the probe needles are arranged to correspond to the pair of target windows, respectively, and have a reflectivity equivalent to that of the peripheral part of the target window and similar to the central part of the target window. A pair of target needles formed in a shape are arranged, and the alignment between the chip and the probe card and the positional relationship between the pair of target windows and the corresponding pair of target needles are automatically determined. A method for automatically aligning a probe card by recognition is provided.

[For production]

According to the above configuration, the state of overlap between the center part of the target window on the chip and the corresponding tip of the target needle on the probe card (that is, the positional relationship between the center part of the target window and the tip of the target needle corresponding thereto) can be determined. , the contrast of the overlapped portions is automatically recognized as a change, and highly accurate positioning of the probe card can be easily achieved based on the data obtained thereby.

(Example) FIGS. 1(a) and (b) show an example of a chip to be measured (actually in a wafer state) to which the present invention is applied. As shown in FIG. 1, a large number of bonding pads 12 are arranged around the chip 11'. Reference numerals 13 and 13' are target windows for alignment of the thousand knobs. Placed in a clear area.

FIG. 1(b) shows the target window 13 (or 13')
is an enlarged view of the target window, which is formed in a predetermined shape using a predetermined material so that there is a clear contrast difference between the center portion 131 and the peripheral portion 132 of the target window. That is, for example, the peripheral part 132 of the target window is formed by patterning with a highly reflective aluminum material or the like, except for the central part (circular hole part) 131 (for example, formed simultaneously with other aluminum wiring patterns), The surface of the chip may be exposed in the central portion 131 as it is.

On the other hand, FIGS. 2(a) and 2(b) show an example of a probe card applicable to the present invention, in which the chip to be measured shown in FIG. 1 is applied.

As shown in FIG. 2(a), a large number of probe needles 22 are arranged around the probe card 21 in correspondence with the bonding pads 12. As shown in FIG. Also, 23, 23
' is the target window 13 on the probe card.
, 13', and the positional relationship between each probe needle 22 and the target needles 23, 23' is similar to that of each bonding pad 12 on the chip. Target window 13, 13
' is configured to exactly match the positional relationship with '.

Here, FIG. 2(b) is an enlarged view of the target needle 23 (or 23'), which has the same reflectivity as the periphery of the target window (in other words, the central part of the target window and the clear It is formed from a material that produces a difference in contrast, such as the aluminum material mentioned above. The tip end 231 of the target needle 23 (or 23') is formed in a shape similar to the center part 131 of the target window (in the case of FIG. 2(b), a circle with a smaller diameter than the center part of the target window).

FIG. 3 is a diagram illustrating a change in contrast accompanying the positional relationship (degree of overlap) between the center portion 131 of the target window and the tip portion 231 of the target needle.
A) shows a case where the positional relationship is inappropriate (in other words, a shifted state), and - side and FIG. 3(b) show a case where the positional relationship is proper.

In the present invention, whether or not this positional relationship is appropriate can be detected by the state of change in the contrast, and if the positional relationship is deviated, the contrast can be detected as shown in FIG. 3(a). The change in contrast is asymmetrical when viewed from the center of the target window, while if the positional relationship is appropriate, the change in contrast is symmetrical when viewed from the center of the target window, as shown in Figure 3(b). becomes. Based on the detection results, predetermined corrections are made so that the positional relationships between each of the target windows and the corresponding target needles are at appropriate positions as shown in FIG. 3(b). (Correction of the position in the X and Y directions of the chuck on which the wafer is placed or the above card θ)
is performed automatically, thereby achieving proper alignment of the probe card with respect to the chip with high precision.

In this case, since the shapes of the target window and the tip of the target needle are simple, pattern recognition using an image sensor or the like can be used as a means of detecting the degree of shape, thereby facilitating the automatic positioning. It can be realized.

FIG. 4 shows the above-mentioned second chip for the chip shown in FIG.
5 is a diagram illustrating the overall configuration of a device for aligning the probe card shown in FIG. 4, and FIG. 5 is a flowchart illustrating a procedure for performing the alignment using the device shown in FIG. 4. It is.

As shown in the above FIG.
The chuck driver 52 exchanges position commands with the CPt 17 via the chuck driver controller 53. Further, the rotational position (card θ) of the probe card 21 is adjusted by a card θ driver 27, and the card θ driver 27 exchanges position commands with the CPU 7 via a card θ driver controller 28. Further, the positions of image sensors 61 and 62 placed diagonally with respect to the chip to be measured are adjusted by image sensor drivers 63 and 64, and the image sensor drivers 63 and 64 are controlled by the CPU 7 via an image sensor driver controller 65. Position commands are exchanged between the two. Furthermore, the image sensor 61
, 62 is analyzed by an analyzer 66, and the analyzed data is input to the CPU 7. Furthermore, the CPU 7 is supplied with information stored for each product type (for example, information on the chip size of each wafer, the position and shape of the target window, etc.) from the memory 81,
Based on the data from each image sensor analyzed by the analyzer 66 and information input from the memory 81, the CPU 7 supplies predetermined position commands to each of the driver controllers.

The amount of movement (X) based on the position command.

The amount of movement in the Y direction, the rotation angle, etc.) are detected by, for example, an encoder on each driver side and sent back to the CPU side. Note that 82 indicates an external auxiliary storage device connected to the memory 81.

Next, a procedure for aligning the probe card using the apparatus shown in FIG. 4 will be described with reference to FIG. 5. It is assumed that the parallel alignment of the wafer (that is, parallel alignment between the scribe line on the wafer and the X and Y moving directions of the chuck by adjusting the chuck θ) has already been performed.

Next, as shown in step 1 of FIG. 5, each image sensor driver is driven by a command from the CPU 7 to which information from the memory 81 is supplied, and the probe is inserted into each image sensor 61, 62. The positions of the respective sensors 61 and 62 are determined so that the target needles 23 and 23' of the card enter. Next, in step 2, the position of the chuck 51 is determined, for example, manually, so that the target windows 13, 13' of the chip to be measured, which are opposed to the respective target needles, are placed in the respective image sensors 61, 62, respectively. Then step 3
, the CPU 7 based on the information from the memory 81 and the data from the one image sensor 61
The movement of the chuck driver in the X and Y directions is controlled by commands from the target window 13.
and the target needle 23 (hereinafter collectively referred to as target 1) in the X and Y directions, and once their positional relationship is adjusted to the appropriate positional relationship as shown in FIG. 3(b) above. I will make it happen. Then, in step 4, the CPU based on the information from the memory 81 and the data from the other image sensor 62
7 controls the movement of the chuck driver in the X and Y directions again, thereby moving the target window 13' and the target needle 23' (hereinafter collectively referred to as target 2) in the X and Y directions. The alignment was carried out, and their positional relationship was determined as shown in Fig.
Make sure that they are properly positioned as shown in the figure below. In addition, as the chuck driver moves to perform this alignment, the positional relationship between the target window 13 and the target needle 23 (that is, the target 1) becomes deviated again, and the The amount of movement in the X and Y directions is determined by the amount of movement in the target window 13' and the target needle 23' when the position where the target window 13 and the target needle 23 (that is, the target 1) are aligned in step 3 is taken as the origin.
(that is, target 2).

Then, in step 5, from the amount of movement of the chuck driver in the X and Y directions when the target 2 was aligned in step 4, it is determined that between the targets 1 and 2, that is, between the chip under test and the probe card. The CPU 7 calculates the θ deviation (deviation of the card θ), and in step 6 it is determined whether the θ deviation is within an allowable range.

If the θ deviation is not within the allowable range, in step 7, the card θ is adjusted according to the calculated θ deviation value.
Correct.

On the other hand, if the θ deviation is within the allowable range, then in steps 8 and 9, in order to adjust the Hm in the X and Y directions, the X , perform alignment in the Y direction. In this case, the positional relationship between the targets 1 and 2 should naturally be within the permissible range, and if this is confirmed in step 10, the probe card alignment work is completed in step 11, On the other hand, if at least one of the positional relationships between the targets 1 and 2 is not within the predetermined tolerance range in step 10, it is assumed that there was an error in calculating the deviation of the card θ, and step 12 is performed. An error message is displayed or the alignment operation is stopped.

Note that even if a predetermined correction is made to the card θ in step 7, the process returns to step 3 again to perform further fine adjustment and confirm the final proper position, and the subsequent steps are repeated.

〔Effect of the invention〕

According to the present invention, the chip and the probe card can be aligned, for example, by aligning a pair of target windows provided on the diagonal of the chip and the corresponding target needles on the probe card, In this case, automatic alignment using pattern recognition can be easily used.
Positioning of the probe card can be performed automatically with high precision and at high speed.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are diagrams illustrating the configuration of a chip to be measured to which the present invention is applied. FIGS. 2(a) and (b) are diagrams illustrating the configuration of a probe card to which the present invention is applied. Figures 3(a) and 3(b) show an example of the above applied to the chip under test, and show the positional relationship (degree of overlap) between the target window on the chip under test and the target needle on the probe card side. ), FIG. 4 is a diagram illustrating the overall configuration of an apparatus for aligning probe cards according to the present invention, and FIG. FIG. 6 is a diagram showing a schematic configuration of a prober according to the prior art. (Explanation of symbols) 11... Wafer, 11'... Chip to be measured on wafer, 12... Bonding pad, 13, 1'3'... Target window, 21... Probe card, 22... probe needle, 23,
23'...Target needle, 27...Card θ driver, 31...Tester head, 4...Profer housing, 51...Chuck, 52...Chuck driver, 61, 62... Image sensor, 63, 64... Image sensor driver, 7...
CPU, 81...Memory. (Q) A diagram illustrating the configuration of the measured chip to which the present invention 1 is applied. b) A diagram showing an example of the configuration of a probe card applied to the present invention applied to a chip to be measured. ... Probe needle 31 ... Tester head 51 ... Chuck 52 ... Chuck driver

Claims (1)

[Claims] 1. A probe card in which a pair of target windows are arranged on a chip of a semiconductor wafer such that the periphery of the window has a different reflectivity from the center thereof, and the probe card has probe needles corresponding to each pad on the chip. On the top, a pair of target needles are formed in correspondence with the pair of target windows and have a reflective ability equivalent to the peripheral part of the target window and have a shape similar to the center part of the target window. are arranged, and the alignment between the chip and the probe card is achieved by automatically recognizing the respective positional relationships between the pair of target windows and the corresponding pair of target needles. Automatic probe card alignment method.