Probe head assembly

Details Probe head assembly Probe head assembly

1999-09-15

2001-09-18

Karlsen, Ernest (Department: 2858)

Electricity: measuring and testing

Fault detecting in electric circuits and of electric components

Of individual circuit component or element

C324S754090

Reexamination Certificate

active

06292007

ABSTRACT:

TECHNICAL FIELD
The present invention relates in general to the testing of semiconductor devices, and in particular to a probe assembly for testing such devices.
BACKGROUND INFORMATION
In the course of fabricating semiconductor devices, it is necessary to perform test and burn in operations on the device. In order to carry out these operations, the device temporarily must be held in a test jig of some form in order to establish electrical contact between the input and output (input/output) pads on the device under test (“DUT”) and the test instrumentation. At the die level, this has previously been accomplished in the art by one of two means. One technique, “soft” Tape Automatic Bonding (“TAB”) requires making a temporary bond to the DUT input/output pads. This can give rise to considerable damage to the pads after removal. The second method for holding the DUT in a test assembly is to use a carrier in the form of a multichip module (“MCM”) with probe tips formed from hard metal bumps. The probe tips on the MCM are arranged in a pattern to exactly match the positions of the input/output pads on the DUT. The DUT is aligned with the probe tips by means of either a mechanical “alignment fence” or an optical technique. Because the probe tips are not sufficiently planarizing over the surface of the die, large forces are required in order to ensure good electrical contact with every input/output pad on the die. The hard metal probe tips may damage the pads. Furthermore, both of these techniques sometimes require that the DUT be mounted in a package using a temporary adhesive that can be complicated to remove. As a result, there is a need in the art for an improved test head assembly for the testing of semiconductor devices.
SUMMARY OF THE INVENTION
The foregoing need is satisfied by the present invention which includes a package having electrical contacts adaptable for connecting to device test instrumentation that also holds the DUT, and contains a compliant probe assembly referred to as the probe membrane. The package and probe membrane include features to effect global planarization of the interface between the DUT and the assembly of probe tips. The features that effect the necessary global planarization include one or more compliant bump probe tips, a compliant bonding material to mount the probe assembly in the package, and a compliant bonding layer for attaching the DUT to the package.
An advantage of the present invention is that a sufficient electrical connection between the compliant bump probe tips is made by the use of pressure applied to the outside of the package although, because of lack of global planarization, there may not be such sufficient connection at the location of one or more of the interfaces between the probe tip and the input/output pad at initial contact. Because compliant bump probe tips respond compliantly over a larger range of displacements than do metals, the pressure needed to effect global planarization is lower than with solid metal probe tips, thereby avoiding damage to the DUT.
Overdeformation of the compliant bump probe tips is prevented by another advantage of the present invention. One or more standoff structures are incorporated on the probe membrane. These have less height than the probe tips and have noncompliant properties. If excessive pressure is applied, the standoffs control the amount of deformation of the compliant bump probe tips, avoiding damage to both the compliant bump probe tips and the DUT.
An additional advantage of the present invention is the additional global planarization that is provided by the elastomeric bonding layer used to affix the probe membrane in the package. Because of the compressibility properties of the elastomeric material, deformations needed to adjust for nonplanarity and thereby effect global planarization are less than would be needed to achieve planarization in a “carrier” technique.
Another advantage of the present invention is further global planarization effected by the use of a layer of elastomeric material backing between the DUT and the package to attach it thereto. This elastomeric backing layer performs its global planarization function in the same way as the elastomeric bonding layer that affixes the probe membrane in the package.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.


REFERENCES:
patent: 3832632 (1974-08-01), Ardezzone
patent: 5475317 (1995-12-01), Smith
patent: 5808474 (1998-09-01), Hively et al.
patent: 6072324 (2000-06-01), Farnworth

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