News Column

Patent Issued for Pre-Aligner Search

May 7, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- A patent by the inventors Monteen, Bjorn (San Jose, CA); Ponder, Gustaaf (San Jose, CA), filed on March 23, 2012, was published online on April 22, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8706289 is assigned to FormFactor, Inc. (Livermore, CA).

The following quote was obtained by the news editors from the background information supplied by the inventors: "Probing involves contacting a pad surface of an integrated circuit (IC) with a probe tip. The process involves positioning of probe pads (such as bonding pads on an IC) relative to probe tips. The positioning of bonding pads, in one system, is achieved by positioning a wafer containing the devices under test.

"A semiconductor wafer typically includes many integrated circuits formed in a lattice of devices or integrated circuits. In some cases, a wafer may include a single discrete component rather than an IC, and these components may also be arranged in a lattice on the wafer. Each IC has a plurality of bonding pads that are commonly used to connect the IC to external circuitry or devices. Given the cost of packaging ICs, most ICs are tested in a wafer probing system prior to packaging.

"In order for a wafer to be in the correct orientation, some wafer probing machines require a pre-aligner to manipulate the position of the wafer so that testing probe tips are correctly aligned with bonding pads on the IC when the wafer is in a test position.

"As the semiconductor manufacturing art progresses, wafer manufacturing capabilities allow the production of thinner wafers. However, as a result, warped or thin flexible wafers become more difficult to handle in pre-aligning systems. Hence, it is desirable to provide a wafer handling system and method that can safely handle and transfer thin flexible wafers without causing damage."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "Improved methods and systems are provided for transferring an object between two positions. A pre-aligning chuck or spindle may rotate a device to a desired position for further testing or inspection.

"According to one embodiment of an aspect of the invention, a warped flexible wafer is received to be transferred between a first mechanism and a second mechanism. A first vacuum suction is sensed between the warped flexible wafer and the first mechanism. The warped flexible wafer is positioned to define a gap between the warped flexible wafer and the second mechanism. The gap is incrementally closed between the warped flexible wafer and the second mechanism. At each increment, a controller determines if a second vacuum suction is detected and whether a second vacuum suction is created between the warped flexible wafer and the second mechanism.

"The first vacuum suction between the warped flexible wafer and the first mechanism is released when a second vacuum suction is detected between the warped flexible wafer and the second mechanism. According to another aspect of the present invention, the first mechanism is a transfer arm and the second mechanism is a pre-aligning chuck and a compliance in the warped flexible wafer allows a transfer between the transfer arm and the pre-aligning chuck mechanism to occur without damaging the warped flexible wafer.

"According to another aspect of the present invention, the first mechanism is a pre-aligning chuck and the second mechanism is a transfer arm, wherein a compliance in the warped flexible wafer allows a transfer between the transfer arm and the pre-aligning chuck mechanism to occur without damaging the warped flexible wafer.

"In one example of the present invention, the closing of the gap includes incrementally moving the first mechanism, the second mechanism, or both. In a further example of a method and system according to the present invention, the moving includes incremental movements of about 5 mils.

"In one example of the present invention, the warped flexible wafer is flattened on a surface of the pre-aligning chuck that is configured to rotate the flexible wafer to a pre-aligned position.

"In one example of the present invention, the pre-aligned flexible wafer is transferred from the pre-aligning chuck to a test position to allow probing of the flexible wafer. In another example of the present invention, the warped flexible wafer is transferred from the transfer arm to a storage position.

"In one embodiment, the compliance of the warped flexible wafer during transfer from the first mechanism to the second mechanism allows for at least 1 mm of flexing to occur with the warped flexible wafer without causing damage to the warped flexible wafer. Furthermore, in another embodiment, the warped flexible wafer has 1 to 12 mm of warping.

"According to another aspect of the present invention, a machine readable storage medium having stored thereon data representing sequences of instructions, which when executed by a computer system cause the computer system to perform a method, is provided. A warped flexible wafer is received and transferred between a first mechanism and second mechanism. A sensor senses the first vacuum suction between the warped flexible wafer and the first mechanism. The warped flexible wafer is positioned in a position defining a gap between the warped flexible wafer and the second mechanism. A gap is closed incrementally between the warped flexible wafer and the second mechanism. A sensor detects, at each increment, whether a second vacuum suction is created between the warped flexible wafer and the second mechanism. The first vacuum suction is released between the warped flexible wafer and the first mechanism when a second vacuum suction is detected between the warped flexible wafer and the second mechanism.

"According to another aspect of the present invention, a machine readable medium is provided where the first mechanism is a transfer arm and the second mechanism is a pre-aligning chuck. A compliance in the warped flexible wafer allows a transfer from the transfer arm to the pre-aligning chuck mechanism to occur without damaging the warped flexible wafer.

"According to another aspect of the present invention, a machine readable medium is provided where the first mechanism is a pre-aligning chuck and the second mechanism is a transfer arm. A compliance in the warped flexible wafer allows a transfer from the pre-aligning chuck to the transfer arm to occur without damaging the warped flexible wafer.

"In one example of the present invention, a machine readable medium is provided where closing the gap includes incrementally moving the first mechanism, the second mechanism, or both. In another example, the machine readable medium is provided to cause incremental movements of about 5 mils.

"In another example, the machine readable medium is provided where the compliance of the warped flexible wafer during transfer from the first mechanism to the second mechanism allows for at least 1 mm of flexing to occur with the warped flexible wafer without causing damage to the warped flexible wafer.

"According to one embodiment of an aspect of the invention, a system is providing having a base, a first mechanism supported by the base and configured to engage a warped flexible wafer with a first vacuum suction. A second mechanism is also provided being supported by the base and configured to engage the warped flexible wafer with a second vacuum suction. The second mechanism also receives the warped flexible wafer from the first mechanism. In one example, at least one sensor is provided and coupled with the first and second mechanism. In another example, the at least one sensor is configured to determine whether the warped flexible wafer is engaged with a respective mechanism after a gap is incrementally closed between the first and second mechanism.

"According to one embodiment of an aspect of the invention, a control system coupled with the at least one sensor is provided. The control system is configured to receive information at each increment from the at least one sensor. The control system also determines whether to release the first vacuum suction between the warped flexible wafer and the first mechanism when a second vacuum suction is detected between the warped flexible wafer and the second mechanism.

"In one example, a system is provided where the first mechanism is a transfer arm and the second mechanism is a pre-aligning chuck and a compliance in the warped flexible wafer allows a transfer between the transfer arm and the pre-aligning chuck mechanism to occur without damaging the warped flexible wafer.

"In another example, a system is provided where the first mechanism is a pre-aligning chuck and the second mechanism is a transfer arm. A compliance in the warped flexible wafer allows a transfer from the transfer arm to the pre-aligning chuck mechanism to occur without damaging the warped flexible wafer. In one example, a system is provided for closing the gap incrementally by moving the first mechanism, the second mechanism, or both.

"The solutions provided by at least certain embodiments of the invention thus results in a system that improves the pre-aligner transfer of thin flexible wafers. In certain embodiments, these thin flexible wafers may contain a plurality of die, each of which contains a discrete electrical component such as a power transistor with a back side contact. These and other embodiments, features, aspects, and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description and appended claims which follow."

URL and more information on this patent, see: Monteen, Bjorn; Ponder, Gustaaf. Pre-Aligner Search. U.S. Patent Number 8706289, filed March 23, 2012, and published online on April 22, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=34&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=1692&f=G&l=50&co1=AND&d=PTXT&s1=20140422.PD.&OS=ISD/20140422&RS=ISD/20140422

Keywords for this news article include: Electronics, Semiconductor, FormFactor Inc..

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Source: Electronics Newsweekly


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