Patent Application
20120043987
1. Technical Field
The present invention relates to a probe card for testing semiconductor devices, and more particularly, to a probe card for testing semiconductor devices having at least one wave spring configured to provide vertical displacement for relieving the stress generated as the vertical probe contacts the device under test.
2. Background
Generally, it is necessary to test the electrical characteristics of semiconductor devices at the wafer level to check whether the semiconductor device satisfies the product specification. Semiconductor devices with electrical characteristic satisfying the specification are selected for the subsequent packaging process, while the other devices are discarded to avoid additional packaging cost. Another electrical property test is performed on the semiconductor device after the packaging process is completed to screen out substandard devices and increase the product yield.
There are two major types of probes according to the prior art, i.e., the cantilever probe and the vertical probe for semiconductor device. The cantilever probe provides appropriate vertical displacement when the probe tip contacts a semiconductor device under test via a cantilever contact structure designed to prevent the semiconductor device under test from being exposed to excessive probe pressure applied by the probe tip. However, the cantilever contact structure occupies a large planar space in a matrix array probing, which constrains the cantilever probe from being arranged in a fine pitch manner corresponding to a semiconductor device with high density of pins, and therefore such arrangement cannot be applied to the testing of the semiconductor devices with high density of pins.
The vertical probe for semiconductor device testing offers the vertical displacement required by the probe tip to contact the semiconductor device under test using the deformation of the probe body itself, and can be arranged in a fine pitch manner corresponding to the semiconductor devices under test with high density of pins. However, if the deformation of the probe body is large enough that adjacent probes may contact each other, this may cause short circuits or collisions.
U.S. Pat. No. 5,977,787 discloses a vertical probe for semiconductor device assembly for checking the electronic properties of semiconductor devices. The vertical probe for semiconductor device assembly includes a buckling beam, an upper plate and a bottom plate. The vertical probe is used to contact the pad of the device under test to build a path for propagating the test signal, and bends itself to relieve the stress generated as the probe contacts the device under test. The upper plate and the bottom plate have holes to hold the buckling beam, and the hole of the upper plate deviates from the hole of the bottom plate, i.e., it is not positioned in a mirror image manner. In addition, frequent bending of the vertical probe for semiconductor device is likely to generate metal fatigue and the lifetime of the vertical probe is thereby limited.
U.S. Pat. No. 5,952,843 discloses a vertical probe for semiconductor device assembly for checking the electronic properties of semiconductor devices. The vertical probe for semiconductor device assembly includes a bend beam, an upper plate and a bottom plate. The vertical probe has an S-shaped bend portion configured to relieve the stress generated as the probe contacts the device under test. In addition, the upper plate and the bottom plate have holes to hold the buckling beam, and the holes of the upper plate and the bottom plate are positioned in a mirror image manner, without deviation from each other.
U.S. Pat. No. 4,027,935 discloses a contact for a contactor assembly having a pivotable end and a pre-curved center section, which deflects in combination with the pivoting of the pivotable end to provide minimal forces on contact pads when a force is applied between the pad and the contactor assembly. The pre-curved center section has a large radius and is arranged such that the pivotable end and the contacting end of the contact are offset from one another within the plane including the radius of the center section so that the deflection direction is predetermined and deflection forces are reduced.
One aspect of the present invention provides a vertical probe for testing semiconductor devices having at least one wave spring configured to provide vertical displacement for relieving the stress generated as the vertical probe contacts the device under test and a probe card for testing semiconductor devices using the same.
A vertical probe for semiconductor device testing according to this aspect of the present invention comprises a bottom contact and a top contact stacked on the bottom contact in a substantially linear manner. In one embodiment of the present invention, the bottom contact includes a plurality of first wave springs stacked one on top of another in a crest to crest manner, the bottom contact has a bottom opening configured to contact a device under test, and the wave spring is configured to provide a vertical displacement for relieving the stress generated as the vertical probe contacts the device under test, wherein the width of the top contact is greater than the width of the bottom contact.
Another aspect of the present invention provides a vertical probe for testing semiconductor devices comprising a bottom contact and a top contact stacked on the bottom contact in a substantially linear manner. In one embodiment of the present invention, the bottom contact includes a first wave spring having a plurality of spring turns, each spring turn includes at least one crest portion and at least one trough portion, adjacent pairs of spring turns contact one another in a crest to crest manner, the first wave spring has a bottom opening configured to contact a device under test, and the first wave spring is configured to provide a vertical displacement for relieving the stress generated as the vertical probe contacts the device under test, wherein the width of the top contact is greater than the width of the bottom contact.
Another aspect of the present invention provides a probe card for testing semiconductor devices comprising a guiding member having a plurality of holes, a circuit board positioned on the guiding member and having a plurality of contact sites facing the holes, and a plurality of vertical probes positioned in the holes. In one embodiment of the present invention, each vertical probe includes a bottom contact having at least one wave spring configured to contact a device under test, and the wave spring is configured to provide a vertical displacement for relieving the stress generated as the vertical probe contacts the device under test.
The conventional vertical probe for semiconductor device testing uses a crown probe tip, which damages the solder ball of the device under test as the vertical probe contacts the device under test. For example, as a four-claw crown probe tip contacts the solder ball, a four-claw imprint is formed on the solder ball because the stress generated as the vertical probe contacts the device under test is applied to a small contact area.
In contrast, the disclosure of the present invention uses the wave spring with the bottom contact serving as the probe tip, and the wave spring contacts the solder ball with a larger ring-shaped contact area so as to reduce the damage of the vertical probe on the solder ball. In addition, the wave springs are stacked one on top of another in a crest to crest manner, and the current can flow through the connected crest portions from one wave to another wave, i.e., there are multiple paths for the current, rather than a single coil flowing path, which will generate inductance effect and influence the electrical measurement.
The conventional cantilever probe cannot be applied to semiconductor devices with high-density pads since it requires a lateral space to receive the lateral cantilever. In contrast, the vertical probe for semiconductor device testing of the present application does not need the lateral space for the lateral cantilever, and can provide variable contact force and be applied to the semiconductor devices with high-density pads of very small pitch.
In addition, the conventional vertical probe for semiconductor device testing uses the deformation of the probe body itself to provide vertical displacement for relieving the stress generated as the probe contacts the device under test, but the adjacent probes may contact each other and cause short circuits or collisions if the deformation of the probe body is too large or there is minor misplacement of the probe body. In contrast, the vertical probe for semiconductor device testing of the present application uses the vertical wave height to relieve the stress substantially without a lateral displacement so as to prevent the vertical probes from contacting each other and causing short circuits or collisions.
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 specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures or processes 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.
The objectives and advantages of the present invention will become apparent upon reading the following description and upon reference to the accompanying drawings in which:
In one embodiment of the present invention, the bottom contact 20 has a bottom opening 21 configured to contact a ball 71 of a device under test 70. In one embodiment of the present invention, the bottom contact 20 includes a plurality of wave springs 21 stacked one on top of another in a crest to crest manner. In one embodiment of the present invention, each of the wave springs 21 is formed from a single piece of conductive material and comprises a plurality of upward crest portions 23 and downward trough portions 25, and the crest portions 23 abut the trough portions 25. In one embodiment of the present invention, the wave springs 21 in an uncompressed state have a wave height 20A, i.e., the distance between the upward crest portions 23 and the downward trough portions 25, which is configured to provide a vertical displacement for relieving the stress generated as the vertical probe 10E contacts the device under test 70 in a compressed state.
In one embodiment of the present invention, the bottom contact 30 has a bottom opening 31 configured to contact a ball 71 of a device under test 70, and the width of the top contact 13 is greater than the width of the bottom contact 30. In one embodiment of the present invention, the bottom contact 30 is a wave spring formed from a single piece of conductive material and having a number of spring turns 39. In one embodiment of the present invention, each spring turn 39 has successive waves formed from distinct crest portions 33 and trough portions 35, and the crest portion 33 of one spring turn 39 abuts the trough portion 35. In one embodiment of the present invention, the wave spring 30 in an uncompressed state has a wave height 30A configured to provide a vertical displacement for relieving the stress generated as the vertical probe 10F contacts the device under test 70 in a compressed state.
In one embodiment of the present invention, the bottom contact 20 has a bottom opening 21 configured to contact a ball 71 of a device under test 70, and the width of the top contact 11 is greater than the width of the bottom contact 20. In one embodiment of the present invention, the bottom contact 20 includes a plurality of wave springs 21 stacked one on top of another in a crest to crest manner. In one embodiment of the present invention, each of the wave springs 21 is formed from a single piece of conductive material and comprises a plurality of upward crest portions 23 and downward trough portions 25, and the crest portions 23 abut the trough portions 25. In one embodiment of the present invention, the wave springs 21 in an uncompressed state have a wave height 20A, i.e., the distance between the upward crest portions 23 and the downward trough portions 25, which is configured to provide a vertical displacement for relieving the stress generated as the vertical probe 10G contacts the device under test 70 in a compressed state.
In one embodiment of the present invention, the bottom contact 30 has a bottom opening 31 configured to contact a ball 71 of a device under test 70, and the width of the top contact 13 is greater than the width of the bottom contact 30. In one embodiment of the present invention, the bottom contact 30 is a wave spring formed from a single piece of conductive material and having a number of spring turns 39. In one embodiment of the present invention, each spring turn 39 has successive waves formed from distinct crest portions 33 and trough portions 35, and the crest portion 33 of one spring turn 39 abuts the trough portion 35. In one embodiment of the present invention, the wave spring 30 in an uncompressed state has a wave height 30A configured to provide a vertical displacement for relieving the stress generated as the vertical probe 10G contacts the device under test 70 in a compressed state.
The conventional vertical probe for semiconductor device such as the POGO pins uses the crown probe tip, which damages the solder ball of the device under test as the vertical probe contacts a device under test. For example, as a four-claw crown probe tip contacts the solder ball, a four-claw imprint is formed on the solder ball because the stress generated as the vertical probe contacts a device under test is applied to the small contact area.
In contrast, the disclosure of the present invention uses the wave spring with the bottom contact serving as the probe tip, and the wave spring contacts the solder ball with a larger ring-shaped contact area so as to reduce the damage of the vertical probe on the solder ball. In addition, the wave springs are stacked one on top of another in a crest to crest manner, the current can flow through the connected crest portions from one wave to another wave, i.e., there are multiple paths for the current, rather than a single coil flowing path, which will generate inductance effect and influence the electrical measurement.
The conventional cantilever probe cannot be applied to semiconductor devices with high-density pads since it requires a lateral space to receive the lateral cantilever. In contrast, the vertical probe for semiconductor device testing of the present application does not need the lateral space for the lateral cantilever, and can provide variable contact force and be applied to the semiconductor devices with high-density pads of very small pitch.
In addition, the conventional vertical probe for testing semiconductor devices uses the deformation of the probe body itself to provide the vertical displacement for relieving the stress generated as the probe contacts the device under test, but the adjacent probes may contact each other and cause short circuits or collisions if the deformation of the probe body is too large or there is minor misplacement of the probe body. In contrast, the vertical probe for semiconductor device testing of the present application uses the vertical wave height to relieve the stress substantially without a lateral displacement so as to prevent the vertical probes from contacting each other and causing short circuits or collisions.
Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. For example, many of the processes discussed above can be implemented in different methodologies and replaced by other processes, or a combination thereof.
Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
