JPH02126160A - Test probe - Google Patents

Abstract

PURPOSE: To produce automatic contact friction washing movement and to improve electrical contact characteristics by combining deflection pivot assemblies made of a constant-length spring and a variable-length spring and pressing it to a device being tested. CONSTITUTION: Pivot assemblies 30 and 38 made of one constant-length and two variable-length springs are provided at an equal interval between a support stand 12 and a traveling stand 28. Due to the asymmetry caused by this sort of combination, a leaf spring 32 of the assembly 38 is deformed in S shape due to the operation of an extension spring and the outside part of a cross slot 40 of the traveling stand 28 is bent toward the support stand 12 when a test probe 10 is pressed against a device. The side movement slightly displaces the move of the traveling stand 28 sideways and causes the oxide covering of the test device to be polished, thus improving the electrical contact between the contact pad of the device to be tested and the contact bump of the test probe.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a test glove used for testing semiconductor devices and the like.

[Technical background of the invention and its problems]

Non-destructive methods of testing integrated circuits are known to those skilled in the art of semiconductor fabrication. Integrated circuits are generally made of sea urchins. Before cutting the wafer into individual chips, the circuits must be tested and qualified.

Testing of chip circuits is typically performed while the chip circuits are still together on a single wafer.

Separating the goo, packaging it, and then testing it would be prohibitively expensive. Each way! Analyze hundreds of separated chip devices by passing input signals through each device and monitoring voltage levels at predetermined output locations.

Traditional glove equipment currently in use is highly susceptible to inaccurate results due to poor electrical connections between the test probe and the input/output pads of the chip device under test (DUT). many. Conventional type membrane
) Globe test equipment uses electrical contacts that are pressed into the contact pads of a chip that rests on a silicon wafer. These pads are usually made from aluminum.

The surface of the aluminum is usually coated with a layer of non-conductive aluminum oxide. The depth of these layers is typically 5 to 10 nanometers.

This insulating film impairs the probe's ability to accurately and reliably transmit high frequency signals to circuitry on the wafer.

Problems exist with current technology. In particular, we face difficulties in creating a reliable test system that can test integrated circuits at high speed while maintaining high test accuracy1.
7. The main cause of test inaccuracies is the current flow
− is the large electrical resistance caused by the oxide film.

Therefore, there is a need to develop improved membrane test probes that perform well toward this oxide resistance.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a test probe that has good electrical contact characteristics with a contact bat of a device under test.

[Summary of the invention]

The invention disclosed herein utilizes an oxide abrasive scrubbing motion (oxide polishing) to scrub the contacts on a membrane probe card.
e-abrading scrubbing moti
on). This glove card is used to provide high speed test signals to integrated circuit chips while being grouped together with other chips on the wafer. This innovation improves the performance of existing membrane globe card structures by reducing inaccurate test results resulting from failure of the globe card contacts that make electrical contact with the input and output ports of the device under test.

The present invention overcomes the problem of uncertain test results resulting from poor electrical contact between the test probe and the input/output ports of the DUT. The present invention uses this as a contact bar,
This is done by scraping the oxide off the board and allowing effective electrical contact to be made.

This probe uses a translation stage that engages a central portion of an extensible flexible membrane that includes conductive signal lines and contact bumps. The periphery of the membrane is mounted on a circular support. The translation table consists of one barb assembly of constant length (i.e., the first
spring) and a pair of variable length spring assemblies (i.e., a second spring and a third spring) within the area of the support base.

All three assemblies use leaf springs (i.e., fourth springs) that extend radially from the periphery of the carriage to the inner edge of the support platform. The first variable length assembly employs an extension spring and a leaf spring consisting of a group of three milling slots surrounding the end of the leaf spring near one of the hexagonal edges of the carriage. This introduces an asymmetric structure.

Due to the asymmetry introduced by the combination of a constant length spring and two variable length springs, a slight but controlled lateral movement of the carriage as it moves and contacts the device under test (DUT) A polishing movement occurs. This lateral scrubbing motion results from the imbalance of freedom of movement created by the constant length and variable length support assemblies.

When the carriage lowers and contacts the wafer, it first moves perpendicular to the support and parallel to itself. The constant length spring (i.e., the first spring) rotates upward in response, pulling the carriage towards itself. The second and third springs respond by loosening to provide some slack to the carriage.

As a result, the carriage moves horizontally towards the constant length spring.

The flexibility or "play" of the support system allows this small lateral movement, but the outer part of the carriage bends in the radial direction defined by the second or third spring. Contribute to trends. This tendency to bend in a particular direction is caused by the three milling grooves that make up each extension spring.

[Embodiments of the invention]

The figures, detailed description, and summary presented below are merely representative of one exemplary structure made in accordance with the claims of the invention.

Of all sample structures that may be made in accordance with the claims, the inventors believe that the particular sample structure described herein is the best mode sample structure embodying the claimed invention. I believe.

System Overview Generally speaking, the present invention provides an apparatus IO that generates an automatic lateral impact scrubbing motion when a test membrane 22 of a test glove engages a device under test (DUT) (not shown). do.

The device 10 comprises a plurality of bending means 30, 38, 38, including at least one spring 30 with a constant length and at least one spring 38 with a variable length.

Also, a plurality of electrically conductive means 23 configured to transmit a plurality of electrical signals between the test glove of the apparatus 10 and the DUT.
．． It also has 25.60.

The device IO further comprises a flexible planar means such as a membrane 22, which is configured to be elongated and has a plurality of electrically conductive means 23.
．． 25, and 60.

The device 10 also comprises a displacement means 28 formed with an upper surface 29 arranged and formed to mate with at least one of the bending means 30, 38, and 38 and with a lower surface 54.

The surface 54 is formed to define an aperture 51 therethrough, the aperture 51 being formed to secure the flexible planar means 22 above itself when extended.

Surface 54 is arranged to mate with flexible planar means 22. Finally, a moving means 28 and a plurality of bending means 30
．． 38, and peripheral support means 12 configured to support 38.

System details Figure 1 shows mounting hole t = i and three circumferential slots 16
1 shows a membrane tube 10 bounded by a circular support 12 with . The upper ring 18 is attached to the top of the inner edge of the support base 12 and extends over the protective layer 20 over the circular flexible membrane 22.
is held. The membrane 22 is held in place between the protective layer 20 and the support base 24, which includes a lower ring portion 26 around its inner diameter.

FIG. 2 is a top view schematically representing the top surface of membrane 22 with a generally radial pattern of conductive signal lines 23. FIG. The line 23 extends around the membrane 22 and is connected to a terminal 25 . These terminals are accessed through the terminals 1-16 of the support. Lines 23 and terminals 25 are omitted from FIG. 1 to simplify the perspective view of the present invention.

Hexagonal carriage 28 is supported centrally on support platform 12 by three flexure pivot assemblies 30, 38, and 38. One pivot accelerator is a leaf spring 3
2 is a fixed length flexure pivot assembly 30 attached to support base 12 by 2. The spring 32 is clamped between a pair of compression blocks 350 on the support base 12 and to a similar pair on the top surface 29 of the moving base 28 by a compression block 36 .

The behavior of the moving table 28 is determined by the mounting angle 33 formed by the intersection of the leaf spring 32 and the horizontal plane of the support table 12. Corner 33 will be explained in detail below. Compression blocks 35 and 36 are all connected by screws 34. The second and third flexure pivot assemblies, both labeled 38, are each spaced along a radial direction extending 120 degrees from the constant length assembly 30.

The hexagonal carriage is aligned such that each of the three radii created by the three assemblies 30, 38, and 38 is disposed perpendicular to the hexagonal peripheral edge of the carriage 28. . Each of the two variable length deflection pivot assemblies 38 has a leaf spring 32.2 pairs of compression blocks 3
5 and 36 and their associated screws 34, and further comprises an extension spring 39 and a part that behaves [-] above the moving platform 28.

Each pair of compression springs 36 is surrounded by three machined grooves with extension springs 39. Each of the two extension springs 39 has a transverse slot 40 and an rHJ transverse force slot 42.
It is equipped with The carriage 28 has two narrow elongated transverse slots 40 between its hexagonal peripheral edges and the center. Each of these transverse slots 40 is parallel to the hexagonal edges of the carriage 28 and perpendicular to the leaf springs 32.

Lateral force slots 42 are raised on either side of the compression block 36, both of which are connected to the transverse slot 40 and the carriage 28.
adjacent to the edge of the hexagon. The distance 44 between each transverse slot 40, its width and its associated set of lateral force slots 42, is a decisive parameter determining the action of the extension spring 9, as will be explained in more detail below. explain.

FIG. 3 shows that the moving table 28 has an additional deflection pivot arm (-:
It is also shown that there are several pairs of additional mounting holes 46 for mounting. These holes surround window assembly 47. Window assembly 47 covers opening 51. Assembly 47 consists of an upper ring 48, a plurality of mounting screws 50, a window 52, and a central transparent disk 56 extending from window 52 through an insulating lower ring 54 of the carriage to membrane 22.

The disk 56 has an alignment bin 5 embedded in its upper surface.
8 to securely hold the disc 56 inside the aperture 51. Window assembly 47 allows a user of probe 10 to visually align the probe over a wafer of a device under test (not shown).

FIG. 3 also shows a plurality of contact bumps 6 connected through the membrane 22 by a plurality of conductive contact bump wires 61.
It also shows 0. The reader is referred to the July 1988 El.
izabeth A.

Co-owned l-1 commonly assigned patent application filed by Be1loli et al. Micro-8trip Archi
texture for Membrane Te5t
See Probe J.

FIG. 4 best illustrates the operation of membrane probe 10 with automatic contact scrubbing. Compression blocks 35 and 36 and leaf spring 32 are schematically shown before and after probe 10 contacts the device under test (not shown). Da7・
Reference numbers 32' and 36' indicate the biased position of the temporary spring and compression spring after contacting the test device.

When the carriage 28 reaches its target, it is pushed upwards parallel to itself relative to the support platform 12. , this moving table 28
Due to the lifting force applied to the plate spring 32, the end of the movable base rotates upward, pulling the movable base 28.Conversely,
When the other two leaf springs 32 are deflected, they each allow the entire carriage 28 to be displaced slightly in a direction parallel to the radius defined by the fixed length deflection pivot assembly 30 in the aquatic plane.

FIG. 4 shows that the difference in lateral elasticity between constant and variable deflection ex vivo, throat assemblies 30, 38, 38
8 is shown to produce a slight but precise side-to-side lateral movement, shown as displacement distance 62, as it descends and contacts the device under test. The displacement 62 is the moving table 2
It is approximately equal to 1/10 of the vertical movement distance of 8.

Due to the extension spring 39, the transverse slot 4 () of the moving carriage 28
The outer portion of the support 12 bends outward toward the support base 12 . Narrow elongated transverse slots 40 and "11" shaped transverse slots 42 on the carriage provide relatively low resistance to bending in a direction parallel to the longitudinal axis of leaf spring 32, but resist applied torque in other directions. I can withstand it.

This l-lux resistance property is important because the carriage 28 must be constrained to move cleanly in a vertical axis parallel to itself without allowing the membrane 22 to tilt out of the horizontal plane. . If the contact bump 6 (2) does not have the resistance to high torque, such tilting will cause misalignment of the contact bump 6 () on the device under test.

The spring force generated by the extension spring 39 is applied to the transverse slot 1 4
0 and the separation of the lateral slots 42 (determined by - The distance between the ends of the pair of transverse force slots 42 also influences the behavior of the extension spring 39.

As the distance between the ends of the slots 7) 42 (in a direction parallel to the length of the plate spring 32) decreases, the resistance to bending of the extension spring 39 decreases. The transverse slot distance 44 selected for the preferred embodiment construction is 0,015 inches (0,381+1I
11). The distance between the ends of the transverse slots 42 is typically 0.68 inches (17,45111111).
It is.

The spring force generated by the variable length deflection pivot assembly 38 in the best mode of the invention is approximately 2.5 per inch.
00 Bond. Given this spring force, constant length flexure pivot assembly 30 must exert a two bond force on carriage 28 to produce 20 microns of lateral movement.

The scrubbing action of the flexure pivot assembly can be set by preloading its spring element.

Another way to control the polishing behavior of the moving platform is to select the mounting angle of the leaf springs at a certain angle with respect to the horizontal plane defined by the support platform 120 and the base 24.

For leaf springs that are 0.375 in. (9.53 in.) long, the mounting angle should be 8° (see numeral 33 in Figures 1 and 3).
), the polishing distance 62 generated in response to the displacement of the moving table 280175 microns is approximately 20 microns. Changing the mounting angle 33 to increase the polishing movement is easier and more economical than changing the slots 40 and 42 and preloading the extension spring 39.

The resulting scrubbing action is also more easily controlled by adjusting the corners 33 of the leaf springs. Mounting the leaf spring 33 at a slight angle to the horizontal increases the magnitude of the scrubbing motion compared to previous techniques. This mounting method also helps resist unnecessary tilting of the carriage 28 as it is pushed upwardly after contact with a test wafer.

In a preferred embodiment of the invention, the lower ring 54 on the lower surface of the carriage 28 is constructed from a non-electrically conductive material, ie, a dielectric. Plastics such as Lexan are suitable for this purpose.

This is because the plastic insulates the membrane 22 from the metal of the carriage 28 and the polyimide membrane 22 is insulated from the metal of the carriage 28.
This is because it protects against some of the abrasion that can occur when the membrane 22 is rubbed against it.

Alternative embodiments of the invention may use more than two or three flexure pivot assemblies. Leaf spring 3
2 can be replaced by a flexible member such as a rod, rod or coil 5 capable of supporting the carriage 28 under suitable tension 1; Similarly, the tension spring 39 occupies the area of the carriage 28. It is not necessarily restricted in this way.

Any device that functions to introduce asymmetry into the support structure of the carriage 28 can be used. The tension spring 39 may be a separate component that connects the carriage 28 to the support platform 12 through an equivalent form of spring 32 comprising the carriage 28.

In the dual preferred embodiment, the extension spring 39 has three slots milled into the carriage 28.

The shape and location of these grooves may vary without departing from the spirit and scope of the invention. The contours of the carriage can also be changed to suit different support system configurations.

Membrane probes with automatic contact polishing are typically used with a stationary chuck while the test wafer is stepped under the probe by a moving chuck.

In conclusion, the present invention is designed to scrape oxides from electrical contact pads so that effective contact can be formed between the membrane and the semiconductor device under test (1) UT) (not shown). A membrane test probe 7 [10] is provided. The support stand [12] has three pivot assemblies 1Jc30.3
8.38] supports the moving platform [28].

The first pivot assembly, a constant length deflection pivot assembly, includes a pair of compression blocks (3, 4)
leaf spring [32] connected to the support base [12] by
It is equipped with The second and third pivot assemblies have leaf springs [32] acting as extension springs 39 on the carriage [2].
8] is a variable length flexure pivot assembly that mates with the area on the top surface [29].

Each extension spring [39] has its associated leaf spring [32] and a pair of "HJ-shaped lateral slots [4] installed on either side of the compression block [35] above the carriage [28].
A narrow elongated transverse line running perpendicular to [2]
0]. The hexagonal carriage [28] has a window [5] at its top which is held in place by the upper ring [48].
2] is provided with a central opening [51] covered by a window assembly IJ (47).

The window [52] rests on a transparent central disk 5G] which is placed inside the opening [51] defined by the insulating lower ring [54]. Conductive contact bump (6f)
] The flexible membrane [22] supporting the support base [12]
It is supported from the periphery of the opening [51] and extends across the opening [51]. The three contact bumps [6o] face away from the carriage [28] and are pushed into the entry/exit door of the device under test (not shown).

The signal from the device under test is transmitted to the probe [1o] and transmitted to the terminal [25] via the signal line [23].The C1 terminal [25] has a protective layer [25] provided on the membrane [22]. 20] through Throno l-(16).

Fixed length and variable length flexure pivot assemblies [3]
The asymmetry obtained by the combination [0,38] generates an automatic contact scrubbing movement whenever the test probe [10] is pressed against the device under test. When the carriage 28 is thrust upwardly as it pushes the device under test through the contact bumps [60], the leaf springs [32] in the fixed length deflection pivot assembly IJ (38) move away from the device under test. It is simply displaced upwards.

In contrast, two variable length deflection pivot assemblies l[
The leaf spring [32] of 38) deforms into an "S" shape due to the action of the extension spring [39], and as a result, the outer part of the transverse slot h [40] of the moving platform [28] becomes the support platform [12]. Turn towards. This lateral movement imparts a slight lateral displacement [62] to the movement of the carriage [28], which causes the test device to become more aggressive as it makes contact and wears away its oxide coating. Automatically scrubs the aluminum contact pads (not shown) of the test device.

Membrane gloves with automatic contact cleaning are highly reliable systems that enhance the effectiveness of test equipment used in the semiconductor industry.

〔Effect of the invention〕

As explained above, by using the present invention, it is possible to improve the electrical contact between the contact pad of the device under test and the contact bump of the test probe.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of an embodiment according to the present invention. FIG. 2 is a plan view of the embodiment. FIG. 3 is a cross-sectional view taken along line 3--3 in FIG. FIG. 4 is a diagram for explaining the automatic polishing movement according to the present invention. 18: upper ring of support base; 28: moving base; 30 constant length deflection pivot assembly; 32: leaf spring; 38: variable length deflection pivot assembly.

Claims (1)

[Claims] A plurality of deflection means including at least one constant length spring and at least one variable length spring, and a plurality of electrical conductors for contacting electrodes of the device under test to input and output electrical signals. means; an elongated flexible planar means comprising said plurality of electrically conductive means; having an upper surface, a lower surface, and a central opening perpendicular to said surfaces;
a moving means to which at least one of the flexible means is coupled to the upper surface and the flexible planar means is stretched to the lower surface; peripheral support means for supporting the moving means via the plurality of flexible means; A test probe comprising: