JPS63305525A - Method of positioning probing head in inspection of semiconductor wafer - Google Patents

Abstract

PURPOSE:To observe the surface of a wafer and a projected reference line simultaneously by a microscope with an accurate focus by irradiating a glass surface with parallel rays from the upper section of a glass in parallel with an optical axis for the microscope and projecting the effect of a non-light-transmitting reference line on the glass surface onto the surface of the wafer. CONSTITUTION:A small window 5 is formed which is separate only by a regular interval from the position of the support of a probe group 4a on a support member 3 to which the probe group 4a in a probing head 4 is supported, the small window 5 is irradiated with parallel rays l1 by a light source 6 and a lens system 7 from the direction vertical to the surface of a wafer through a semitransparent mirror 8 in the upper section of the small window 5, and the image of a mark such as a cross line on a transparent plate is shaped onto the surface of the wafer. The image of the mark such as the cross line and a mark for confirming the position of the wafer such as pads on the surface of the wafer are observed by an optical microscope 9 from the upper section of the semitransparent mirror 8, and the relative positions of the probing head 4 and the wafer 2 are adjusted, thus positioning the tips of the probe group 4a and pad groups on the wafer 2 to be inspected. Accordingly, said image and mark for confirming the position of the wafer can be observed with an accu rate focus even by a microscope having high magnification, thus improving the precision of positioning.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application: Industry (-1) The present invention relates to a probe head positioning method in a semiconductor wafer inspection apparatus, and is applicable to manufacturing processes of semiconductor devices such as integrated circuits and large-scale integrated circuits. It is related to the method and equipment for testing one wafer in a process, and in particular, it uses a large number of probe needles to inspect the internal circuits or internal connections of a wafer during a process such as electrodes, pads (=1, and wiring). Place the probe head with the
The present invention relates to a method for aligning a probe head of a semiconductor wafer inspection apparatus to a test pattern of a wafer to be inspected in a semiconductor wafer inspection apparatus that performs tests and inspections on a large number of test points.

The increase in the integration density of semiconductor devices inevitably leads to an increase in the number of electrodes and pads on semiconductor wafers, and the complexity of the wiring patterns containing these, which leads to the increase in the number of electrodes and pads on semiconductor wafers, and the complexity of the wiring patterns that include them. The test points in wafer test inspection by 1-bar were increased. 1985 5 J] JP-A-58-80.847 L1, published on the 16th. U.S. Patent Application No. 3 filed November 2, 1981 by Kubatroni Tsuta
No. 17.413 (priority claim based on No. 17.413) has developed a matrix-type test probe head device that can be applied to semiconductor wafers that have a large number of test points and are distributed two-dimensionally. A miniature circuit processing device, ie, a wafer blower, was developed. The main parts of its structure are summarized as follows. It is equipped with a number of probes having probe wires 7 which are inserted into a flexible/lobe guide fixed by supporting means that includes a base plate and a printed wiring board, and which are slidable in the probe guide. In addition, the tip of each of the probe wires t7 can protrude from a large number of guide holes distributed in a matrix of the mounting plate 1, which is made of ceramic or the like, to form a substantially common contact plane. When a pressing force is applied elastically to the end of the probe wire, the probe wire becomes
Since the wire slides in the guide, the tip of each wire A7 protruding from the mounting plate makes electrical contact with each test point forming a matrix distribution (pad pattern) on the sea urchin pigeon. Further, on each side of the mounting plate with respect to the probe wire, a crosshair for IQ alignment μ and a pit array corresponding to the pad pattern of the wafer are formed, which are equal distances in front of the mounting plate, respectively. engraved with first and second marking means, and the first and second observation microscopes (in addition,
For example, one microscope may be used, and it may be configured to selectively take either position with respect to the two axes.

By the way, if the test points of the semiconductor wafer are not arranged in a ring shape on the back, but there are a large number of test points very densely packed in a small area (referred to as a matrix test point arrangement), the target test It is extremely difficult, or even impossible, to directly check with an optical microscope whether or not there is accurate contact between the pad and the probe wire of the probe head because the spacing between the pads is too narrow. close. For this reason, in the above-mentioned prior art, as shown in FIG. A predetermined distance in the perpendicular direction from the axis passing through the center of J-Ahead,
In addition, a small window 14 for positioning U is provided so that the axis is located parallel to the axis, and a cross line and a large number of pit groups are engraved in this small window by Rede engraving or etching. An optical microscope with a glass plate and an optical axis parallel to the axis of the small window? While observing B2, the area 14 on the surface -F of the same wafer 2 where the probe group contacts
By adjusting the crosshairs 13 and the pit group so that they coincide with the corresponding pad pattern 12 in the corresponding area 15 that is a predetermined distance away from the probe group 10, the probe group 4a of the blower head can be adjusted indirectly. The tip is aligned with the pad at the test point.

While attempting to solve the invention, the conventional technique described in E) is to detect the corresponding area on the wafer surface through a small window and to identify the corresponding area on the wafer surface with the 11-character line and bit group on the glass plate provided in the small window. This is to align with the pad pattern, but since there is a minute gap d between the crosshair and the wafer surface,
It is not possible to simultaneously and accurately focus on both the pad pattern, the crosshairs on the glass plate, and the bit group in corresponding areas on the surface of the wafer on the field of view of the microscope.

This is because the depth of focus of the microscope is much smaller than the minute interval d. The following two methods can be considered as means to avoid this difficulty when implementing the prior art. The first method is to make the very small distance d between the crosshairs and bit groups on the glass plate and the corresponding areas on the wafer surface as small as possible. However, in this case, the probes BT#, each of which has its probe guide tips fixed by a support plate at the front end of the probe head, and the tips of their respective probe wires forming a common contact plane L, are used. In order to make contact with the pad pattern at one point on the soy bean, the pressure force acting on the opposite end must protrude beyond the support handle, and the probe head must be protruded using a microscope. To align the probe wire and the wafer, it is necessary to prevent the tips of these protruding probe wires from coming into contact with the wafer, so the shortening of the minute distance described above is limited by the dimensions of this protruding portion. There was a natural limit to the magnification of the microscopes that could be used. Therefore, this has become a prisoner of f, N[i;, which hinders the improvement of test accuracy. Next, the second method is
The optical system of the microscope is +'+n 1% twice)
To do this, I focused twice on each of the crosshairs on the glass plate and the pad pattern in the corresponding area on the wafer surface, and each time I focused on them. , these are compared and observed separately with a reference line fixed to the optical system. However, when this method is adopted, the optical system's downward movement causes vibration at its tip axis, which not only lowers the inspection 111σ, but also makes the focusing U operation troublesome and takes time to adjust. However, in order to ensure the test viscosity, a rigid optical system structure and precise adjustment of the optical axis are required, resulting in a very expensive product.

Means (action) for solving the problem Observe the reference line on the glass fixed to the probe head and the wafer surface with a microscope to align them V, and then align the probe and pad. J to the method of doing U
3. In the present invention, in particular, parallel light rays are transmitted from above the glass,
The above-mentioned problem is solved by irradiating the glass surface parallel to the optical axis of the microscope and projecting an image of a non-transparent reference line on the glass surface onto the wafer surface.

-4 However, according to the method of the present invention, the wafer surface and the projected reference line can be simultaneously observed under a microscope with accurate focus. Therefore, the magnification of the microscope can be arbitrarily selected from consideration of the required viscosity, improvement of operability, etc.

Structure and Embodiments of the Invention FIG. 1 shows an outline of an apparatus used for implementing the probe head positioning method of the present invention in a semiconductor wafer prober, in which 1 supports a semiconductor wafer to be inspected. 2 is a semiconductor wafer in the inspection position; 4 is a probe head;
A is a large number of f rJ-bums located on the wafer head. 3 is a support table provided parallel to the wafer surface on the empty book board 1, and its predetermined position is At the company, a probe head 4 is supported and fixed so that the tip of the probe group 4a can contact the wafer surface from the vertical direction, and a position a predetermined distance D' from the probe head 4 is provided. A small positioning window 5 fitted with a transparent plate made of glass or the like is supported and fixed.This transparent plate is covered with a non-transparent pattern consisting of predetermined cross lines and dots using well-known means. Thus, the adjusting device 41 shown in the figure allows the probe head 4 to be adjusted to a predetermined one.
Also on the glass plate of the small window 5, which is 7i1 distance D' apart (
When the quasi-pattern is adjusted so that the probe group faces a corresponding area on the wafer surface that is a distance D' from the area of the wafer to be contacted, the probe group 4 of the probe head 4
The tip of a comes into contact with a pad pattern (referred to as the pad pattern of tests 1 to +i 14) on the surface of the wafer to be inspected. At this time, since the optical microscope 9 is configured to move integrally with the support table by means of a connecting means (not shown), its tip axis X is always at a position 4 passing through the reference point of the glass plate. In the apparatus of this embodiment embodying the method of the present invention, a translucent mirror, known per se, is provided between the microscope 9 and the small window on the optical axis x, J-, making an angle of 45° therewith. 8, and a lens system 7 for converging the light from the illumination light 'l1A6 into parallel light rays 11 is provided on the side of this translucent 1n8. Therefore, the parallel light Wa11 that enters the semi-transparent mirror 8 from the light source 6 via the lens system 7 is reflected by the semi-transparent mirror 8 and is combined with the parallel light rays 12 and 41 parallel to the optical axis of the microscope through the glass of the small window 5. When the plate is irradiated, an image of a group of non-transparent bamboo crosshairs and a driver 1 formed on the glass is projected onto the pad pattern in the corresponding area on the wafer surface. Figure 3 is a partial diagram showing the situation for reference, 15 is one of the pads that are in the corresponding area and forms the pad pattern, and 13 is the image of the cross line projected on this pad 10. . , Since it is configured in this way, the optical microscope 9
Focus on the surface of the bottles 1 to 1.
If it is, the pad pattern existing in the corresponding area and (
By simultaneously observing the crosshairs formed in the soil and the image of the group of drums 1, the positioning between them can be performed accurately and quickly. Note 1. In the device of the embodiment described above, the lens system 7 and the σ light m6 are translucent IA8
For example, it is fixed at an appropriate location in the connection means of the vA@mirror 9 and the support table 3 so that it can be integrally interlocked with the vA@mirror 9 and the support table 3.

As described in detail of the invention, the alignment Uh method of the present invention is performed by observing the U directrix on the glass surface fixed on the support member of the probe head and the wafer surface using a microscope. Instead of the reference line on the glass surface, the image of the reference line projected onto the glass surface is observed, so even with a high-magnification microscope, both can be observed with precise focus, making it easier to align the positions. Accuracy is increased.

[Brief explanation of drawings]

FIG. 1 is a drawing that clarifies the structure of an embodiment of the probe spatula positioning method for semiconductor wafer inspection of the present invention, and particularly schematically shows the main parts of the apparatus used to carry out the method. FIG. 2 is a schematic diagram showing the prior art method and apparatus on which the present invention is based on its improvement, and FIG. FIG. 2B is a drawing showing the pad pattern and crosshairs in the corresponding area on the wafer in the method of the present invention. It is a drawing illustrating the relationship between the pad inside and the image of the crosshair on the glass plate.

Claims (1)

[Claims] In the inspection of a semiconductor wafer having a matrix-like test point array, a small window is provided on the support member supporting the probe group of the probe head at a predetermined distance from the supporting position of the probe group, and a small window is provided on the side. Parallel light from the disposed light source and lens system is irradiated onto the small window from a direction perpendicular to the wafer surface through the semi-transparent mirror above the small window, and the light beams on the transparent plate attached to the small window are illuminated. An image of a mark such as a non-transparent cross line is formed on the wafer surface, and the image of the mark such as the cross line projected onto the wafer surface is combined with a mark for confirming the position of the wafer such as a pad on the wafer surface. The tips of the probe group and the pad group of the wafer to be inspected can be aligned by observing them with an optical microscope from above the semi-transparent mirror and adjusting the relative position of the probe head and the wafer. Characteristic probe head positioning method.