The present invention relates to integrated circuit (IC) semiconductor devices and, more particularly, to testing the devices.
Large numbers of identical integrated circuits such as microprocessors, memory devices, and digital signal processing devices are generally fabricated on a silicon wafer. Due to defects that may occur during fabrication, each IC (die) on the wafer is typically tested or sorted by test equipment such as automatic test equipment (ATE) machines and probe cards. The test signals are provided to each die through input or input/output (I/O) bond pads on each die, and the test results are monitored on output or I/O bond pads. The good die that pass the wafer-level test are then singulated and packaged typically by electrically connecting the bond pads to the package by means of bond wires, solder balls, or other contact structures. To accommodate the bonding wires or solder balls, the bond pads are generally very large relative to the circuit elements of the integrated circuit. Typical bond pad sizes are on the order of 100 μm (microns)×100 μm (4 mils×4 mils). The bond pads are also typically aligned in regular patterns such as peripherally along the outside perimeter of the die, in a grid pattern, or in a column or row generally through the center of the die (lead-on-center).
The bond pads allow each die as a whole to be functionally tested for specified timing parameters (AC parameters), DC parameters, and overall operation. The bonding pads may also be used to load test patterns and monitor test result from on chip test circuits such as SCAN circuitry and Built-In Self-Test (BIST) circuitry. The on-chip test circuits enhance the overall testing of a die by enabling individual testing of internal circuits or nodes. However, this comes at the expense of increasing the size of the die to accommodate the added test circuitry and additional bond pads needed to support the on-chip test circuitry.
If a die already has all of its peripheral, grid, or lead-on-center bond pad locations dedicated to a device function, then adding additional bond pads in the predetermined bond pad alignment to support the on-chip testing circuitry can result in a substantial increase in the size of the die. Generally, larger die are more prone to defects and consequently more expensive to manufacture. Additionally, on-chip testing circuitry can result in a significant increase in test time as many clock cycles may be required to load test input data and subsequently output test results from a few available bond pads. On-chip testing circuitry also does not allow for direct external access to internal circuit nodes. Test input data and test results must pass through the SCAN circuitry or BIST circuitry before it can be monitored. This introduces additional circuits that can mask failures in the circuit intended to be tested, or can introduce new failures caused by SCAN or BIST circuitry.
Additionally, many designs are I/O limited since only a limited number of leads (e.g., bond wires) may be accommodated in a given packaging scheme. Moreover, to test I/O functionality of a chip, these same lead locations must be used. It would be advantageous to access more points in a circuit, especially for testing. It would also be advantageous if the access points could be located with a high degree of positional freedom. Small size, large number, and arbitrary or selected positioning of the access points would also be advantageous.
One embodiment of the present invention concerns an integrated circuit that includes bond pads and special contact pads or points. The bond pads are for interfacing the integrated circuit as a whole with an external circuit, and are to be bonded to a package or circuit board. The bond pads are disposed on the die in a predetermined alignment such as a peripheral, grid, or lead-on-center alignment. The special contact pads are used to provide external test patterns to internal circuits and/or to externally monitor results from testing the internal circuits. The special contact pads may be advantageously located on the integrated circuit with a high degree of positional freedom. For one embodiment, the special contact pads may be disposed on the die at a location that is not in the same alignment as the bond pads. The special contact pads may be smaller than the bond pads so as not to increase the die size due to the special contact pads. The special contact points may also be used to externally program internal circuits (e.g., nonvolatile circuits) at the die or package level. The special contact points may also be used to select redundant circuits for faulty circuits.
Other objects, features, and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description which follows below.
The features and advantages of the present invention are illustrated by way of example and are by no means intended to limit the scope of the present invention to the particular embodiments shown, and in which:
Special contact pads 112 provide a means for providing test input data to, and monitor signals from, internal circuits 102-106 without having to test the function of the entire integrated circuit. Special contact pads 112 also provide a means for testing internal circuits 102-106 when these circuits are not otherwise individually testable and/or accessible through bond pads 110. For one example, internal circuit 102 may be an embedded memory that is not directly accessible through bond pads 110. Address and input data signals may be provided over several of the special contact pads 112 to provide test patterns to the embedded memory, and another group of special contact pads 112 may receive data read from the memory. The external circuitry providing the test patterns for the embedded memory may provide any number of patterns to increase the fault coverage.
For another embodiment, internal circuit 102 may be a programmable circuit such as nonvolatile memory or programmable logic. Data can be programmed into the internal circuit through the special contact pads 112. For example, BIOS information, program code, and system software may be programmed or updated in programmable circuit 102 after fabrication of integrated circuit 100.
On-chip test circuitry such as SCAN and BIST circuitry may not be required in integrated circuit 100 as test stimuli for integrated circuits 102-106 may be provided directly to special contact pads 112. Additionally, test results may be output to special contact pads 112 rather than bond pads 110. The external test circuitry supplying the test stimuli may provide an increased number of tests without impacting the size of integrated circuit 100. Without SCAN or BIST circuitry included in a test input or output signal path, the likelihood of more accurately determining the location of a failure increases as there is no on-chip test circuitry to mask the failure or to introduce further failures. Additionally, speed parameters or the timing of signals into and out of a circuit block or a circuit node may be more accurately measured and monitored without introducing delays caused by intermediary on-chip test circuitry.
As shown in integrated circuit 100, special contact pads 112 may also work with BIST circuitry 108 (or other on-chip test circuitry) to monitor the response of internal circuit 106 to test stimuli provided by BIST 108. This can be accomplished without having to add additional bond pads 110, or to use existing bond pads 110 to communicate with BIST 108.
As shown in
Special contact pads 112 may also be interspersed between bond pads 110 (e.g., see FIG. 5), or be located outside the region surrounded by bond pads 110. For one embodiment in which special contact pads 112 are interspersed between bond pads 110, it may be advantageous for special contact pads 112 to be smaller than bond pads 110 so as not to increase the size of integrated circuit 100.
Special contact pads 112 may be any size including sizes smaller than bond pads 110. When special contacts 112 are smaller than bond pads 110, more special test pads may be disposed on integrated circuit 100 without increasing the size of the die over that defined by the peripheral bond pads 110. A larger number of special contact pads may increase the number and/or complexity of tests that can be provided to the internal circuit, and thus may increase the fault coverage and robustness of tests. For one embodiment, a bond pad 110 may be approximately 100 μm×100 μm, and a special contact pad may be approximately 5 to 10 μm per side. In other embodiments, the special contact pad may be less than 5 μm per side. For still other embodiments, the special contact pads may be manufactured to have different sizes to accommodate their different spatial locations on the die (e.g., between bond pads 110 vs. within the area surrounded by bond pads 110), to accommodate different dimensions of various probe tips, bond wires, or solder balls, or to accommodate different functions of the circuits under test (i.e., nodes driving output signals may required larger pads than pads for providing input signals, or vice versa). The lower limit for the size of the special contact pads may be limited by the accuracy of the probe-to-pad alignment and the size of the probe.
Special contact pads 112 may be formed into an approximately square shape, rectangular shape, or any other geometric shape. Special contact pad 112 may also have different heights than bond pads 110. Special contacts pads 112 may be fabricated using conventional photolithography processes that are typically used to create bond pads or other, relatively flat, conductive landings. For one embodiment, the special contact pads may be fabricated from one or more metal layers including aluminum, copper, gold, or other metals or conductive materials.
Integrated circuit 100 shows that special contact pads 112 are logically disposed about the circuit block which they test. In alternative embodiments, special contact pads 112 may be physically located at any other location in integrated circuit 100.
Special contact pads 112 may not be permanently bonded out to a integrated circuit package (e.g., typical plastic and ceramic chip packages), rather, the special contact pads may be used for receiving test input information (e.g., address, control, or data) or monitoring internal test nodes or signals. The special contact pads are large enough, however, to receive an electrical contact element (as will be described in more detail below). Given that special contact pads 112 are generally not bonded out to a package, special contacts pads 112 may require significantly less supporting circuitry than is typically required by bond pads 110. Typical bond pads generally include supporting circuitry that requires significant amounts of silicon die are. Examples of supporting circuitry include electrostatic-discharge (ESD) protection structures such as resistors, capacitors, and/or diodes, latch-up prevention circuits such as guard rings, buffers for driving circuits and signal lines external to the integrated device or for buffering internal signals received from external signal lines, logic or voltage translation circuits, and noise reduction circuitry. Special contact pads 112 may reduce the amount of supporting circuitry required. Little no ESD protection may be needed and little or no buffering may be required for an external probe to electrically contact a special contact pad and monitor a signal thereon. For one example, an I/O buffer 120 may be used between an internal test point 124 and a special contact pad 110 as shown in FIG. 3B. The I/O buffer may be controlled by a control signal 122. The I/O buffer 120 may be approximately 10 to 100 times weaker than that required for a bond pad having to drive heavy loads in a PCB environment. Additionally, little or no latch-up supporting circuitry or noise reduction circuitry may be required. For example, a weak pull-up resistor may be all that is required for each special contact pad for noise reduction circuitry. Generally, a special contact pad may require only 1 to 50 percent of the supporting circuitry typically required for a bond pad.
For an alternative embodiment, contact balls 504 need not be formed on bond pads 410.
The embodiments shown in
In response to the data read from memory 702, I/O interface 704 may format the data prior to providing it to I/O drivers 706. I/O interface 704 may receive control signals on special contact pads 714, or internal circuit nodes within I/O interface 704 may be monitored by special contact pads 714. The data output by I/O interface 704 to I/O drivers 706 may be monitored via special contact pads 715. I/O drivers 706 may then drive the data to bond pads 716.
Since special contact pads 713 and 715 and bond pads 716 may be used to monitor the output of each of memory 702, I/O interface 704, and I/O divers 706, respectively, such that incorrect data received at bond pads 716 can be isolated to the circuit which caused the failure. In conventional BIST techniques in which an address, for example, is provided to memory 702, the source of incorrect data received at bond pads 716 would be unknown.
While the embodiment shown in
Special contact pads may also be used to not only isolate failures, but to also enable redundant circuits to be used to replace faulty circuits.
The control signal on line 721 can be driven to the appropriate voltage level or logic state by switch 710. In response to a TOGGLE signal, either voltage V1 or V2 will be selected in response to monitoring the signals at the special contact pads 717 and 715. The TOGGLE signal can be controlled by another special contact pad (not shown).
As discussed above with respect to
Similarly, as shown in
For an alternative embodiment, one or both of pads 1212 may be special contact pads. This may provide for increased design flexibility in the location and use of SCAN circuitry. For example, this may enable multiple SCAN regions or circuits of varying size and complexity to test various different internal circuits or blocks of circuits.
When the special contact pads are available on a die of a wafer, test signals may be supplied to special contact pads, or signals may be monitored at the special contact pads by means of test or probe card assemblies. Probe card assemblies typically include a probe card that has a number of probe elements or contact structures to contact the special contact pads and bond pads. A host controller or other logic device typically communicates with the integrated circuit under test through the probe card.
System 1300 includes a test head 1304 and a probe card assembly 1313. Probe card assembly 1313 includes a load board or interconnection substrate 1306 and cantilevered or needle probe card 1310. Host 1302 communicates test signals with test head 1304. Any type of host may be used including a personal computer, or specialized machines such as Automatic Test Equipment (ATE) provided by LTX, Credence, Teradyne, and others. Test head 1304 typically includes drivers, receivers, and parametric measuring units (PMUs) that communicate signals with load board 1306 and probe card 1310. Load board 1306 is typically a PCB that provides the appropriate mechanical interconnection and load circuits for probe card 1310. In alternative embodiments, load board 1310 may be omitted. Load board 1310 may also include control logic such as logic 1308. Control logic 1308 may be an application-specific IC (ASIC) used to provide tests to die 1311 under the control of host 1302.
Probe card 1310 is a cantilevered or needle probe card that includes cantilevered probes 1318 and 1320 that provide signals to and receive signals from die 1311. Probes 1318 and 1320 may comprise any suitable conductive material including tungsten. As shown in the plan view of probe card 1310 in
Probes 1318 are provided in a predetermined alignment to contact bond pads 1314. As shown in
In another embodiment, probes 1318 may be arranged in a lead-on-center arrangement to align with lead-on-center bond pads on a die, and probes 1320 may be arranged outside the lead-on-center arrangement to align with corresponding special contact pads.
While
For an alternative embodiment, bond pads 1316 and special contact pads 1316 may be of different heights. For example, bond pads 1314 may be taller than special contact pads 1316 (or vice versa). For this embodiment, probes 1318 and 1320 may extend to different depths. That is, probes 1320 may extend lower than probes 1318 to make contact with special contact pads 1316.
System 1500 includes a test head 1504 and a probe card assembly 1513. Probe card assembly 1513 includes a load board or interconnection substrate 1506 and membrane probe card 1510. Like host 1302 of
Probe card 1510 is a membrane probe card that includes contact balls 1518 and 1520 that provide signals to and receive signals from die 1511. Contact balls or probes 1518 and 1520 may comprise any suitable conductive material including solder.
Probes 1518 are provided in a predetermined alignment to contact bond pads 1514. As shown in
While
For an alternative embodiment, bond pads 1516 and special contact pads 1516 may be of different heights. For example, bond pads 1514 may be taller than special contact pads 1516 (or vice versa). For this embodiment, probes 1518 and 1520 may have different heights. That is, probes 1520 may extend lower than probes 1518 to make contact with special contact pads 1516.
System 1800 includes a test head 1804 and a COBRA-style probe card assembly 1813. The COBRA-style probe card assembly is available from Wentworth Laboratories of Brookfield Conn. The COBRA-style probe card assembly includes a load board or interconnection substrate 1806, space transformer (either wired or ceramic) 1808, and head assembly 1807. Head assembly 1807 includes upper plate 1809, spacer 1810, lower plate 1811, and COBRA-style probes 1818 and 1820. Like host 1302 of
Probes 1818 are provided in a predetermined alignment to contact bond pads 1814. As shown in
While
For an alternative embodiment, bond pads 1816 and special contact pads 1816 may be of different heights. For example, bond pads 1814 may be taller than special contact pads 1816 (or vice versa). For this embodiment, probes 1818 and 1820 may extend to different depths (or have different heights). That is, probes 1820 may extend lower than probes 1818 to make contact with special contact pads 1816.
Apparatus 2100 includes a test head 2104 and a probe card assembly 2113 such as that provided by FormFactor, Inc. of Livermore, Calif. One embodiment of probe card assembly 2113 is disclosed in U.S. patent application Ser. No. 08/789,147 filed on Jan. 24, 1997, which is incorporated by reference herein. Probe card assembly 2113 generally includes probe card 2106, interposer 2108, space transformer 2108, and spring contact elements 1218 and 1220. Like host 1302 of
Spring contact elements 2118 are formed in a predetermined alignment to contact bond pads 2114. Probes 2118 may be arranged in a grid array to contact bond pads 2114 aligned in a corresponding grid array pattern. Spring contact elements 2120 may be arranged with the predetermined grid array, outside of the grid array pattern, or interspersed within the grid array pattern to align with corresponding special contact pads 2116 on die 2111. Alternatively, spring contact elements 2118 may be arranged in a peripheral pattern to contact bond pads 2114 arranged on die 2111 in a corresponding peripheral pattern. Spring contact elements 2120 may be aligned in the predetermined peripheral pattern, outside of the peripheral pattern, or within the peripheral pattern to align with corresponding special contact pads 2116 on die 2111. In yet another embodiment, spring contact elements 2118 may be arranged in a lead-on-center arrangement to align with lead-on-center bond pads on a die, and spring contact elements 2120 may be arranged within or outside of the lead-on-center arrangement to align with corresponding special contact pads.
While
For an alternative embodiment, bond pads 2116 and special contact pads 2116 may be of different heights. For example, as shown in
For an alternative embodiment, as shown in
Structure 2406 can be any shape.
Die 2711 includes bond pads 2714 and special contact pads 2716. Wafer 2712 includes die 2711 and may be disposed on a suitable support structure such as vacuum chuck 2726. Die 2711 may embody an integrated circuit such as integrated circuit 100 of
System 2700 includes a support chuck 2704 and a probe card assembly or test substrate. The probe card assembly includes an interconnection substrate (base plate) 2708, an active electronic component 2710, and spring contact elements 2718 an 2720. Component 2710 includes circuitry for applying test signals to an monitoring the test output from, die 2711. For one embodiment, component 2710 may be an application-specific integrated circuit (ASIC).
Like host 1302 of
System 2700 also includes guide pins 2722 disposed around the periphery of wafer 2712 and the probe card assembly to ensure accurate alignment when spring contact elements 2718 and 2720 are urged into contact with bond pads 2714 and special contact pads 2716, respectively. A compression stop (block ring) 2724, which may be suitably disposed on the face of wafer 2712, limits the amount of travel or distance that the tips of the spring contact elements 2718 and 2720 will deflect when urged against the pads of die 2711.
Spring contact elements 2718 are formed in a predetermined alignment to contact bond pads 2714. Probes 2718 may be arranged in a grid array to contact bond pads 2714 arranged on die 2711 in a corresponding grid array pattern. Spring contact elements 2720 may be aligned in the predetermined grid array, outside of the grid array pattern, or interspersed within the grid array pattern to align with corresponding special contact pads 2716. Alternatively, spring contact elements 2718 may be arranged in a peripheral pattern to contact bond pads 2714 arranged on die 2711 in a corresponding peripheral pattern. Spring contact elements 2720 may be arranged with the predetermined peripheral pattern, outside of the peripheral pattern, or within the peripheral pattern to align with corresponding special contact pads 2716. In yet another embodiment, spring contact elements 2718 may be arranged in a lead-on-center arrangement to align with lead-on-center bond pads on a die, and spring contact elements 2720 may be arranged within or outside of the lead-on-center arrangement to align with corresponding special contact pads.
While
For an alternative embodiment, bond pads 2716 and special contact pads 2716 may be of different heights. For example, bond pads 2714 may be taller than special contact pads 2716 (or vice versa). For this embodiment, probes 2718 and 2720 are extended to different depths (or have different heights). That is, probes 2720 may extend lower than probes 2718 to make contact with special contact pads 2716.
For an alternative embodiment, spring contact elements 2718 and 2720 may be attached to bond pads 2714 and special contact pads 2716 on die 2711. For this embodiment, component 2710 may include pads to make contact with the spring contact elements. For yet another embodiment, some of the spring contact elements 2718 or 2720 may be attached to component 2710 and some may be attached to die 2711.
As previously described above, special contact pads can be disposed on a die or on packages such as Land Grid Array (LGA) packages. When special contact pads are disposed on packages or on devices arranged in a C4 or flip-chip configuration, they can provide a means for supplying test signals or programming signals to the special contact pad of the die. This may be advantageous to allow, for example, field programming of packaged programmable logic device or nonvolatile devices without having to provide dedicated bonded out pins for the programming function. Additionally, embedded nonvolatile memory arrays that store program code, application software, or BIOS may be updated in the field. Special contact pads disposed on a package may also provide an advantageous means for testing a faulty device and programming redundant circuits to replace a faulty circuit as described above with respect to
PCB 2810 has a plurality of terminals or pads 2818, and package 2804 have a plurality of bond pads 2812 and special contact pads 2814. Socket 2800 provides a means for electrically interconnecting terminals 2818 with pads 2812 and 2814. Circuitry provided on PCB 2810, or in communication therewith, may provide signals to or monitor signals from pads 2812 and 2814 through socket 2800. For example, programmable circuitry within package 2804 may be programmed or monitored through spring contact elements 2816, special contact pads 2814 and/or pads 2812.
Socket 2800 includes a support substrate 2808 formed, for example, from a conventional PCB material. Support substrate 2808 includes spring contact elements 2816 formed on a top surface thereof, and pads 2822 formed on a bottom surface thereof. Spring contact elements 2816 are for contacting pads 2812 and 2814 of package 2804 when package 2804 is urged downward by a forced applied to the topside of package 2804 by retaining means 2802. Other contact elements besides spring contact elements may also be used. Support substrate 2808 also includes electrical conduits 2824 that provide an electrical interconnection between spring contact elements 2816 and pads 2822. For an alternative embodiment, spring contact elements 2816 may be connected directly to terminals 2818.
Contact balls (such as conventional solder balls) are disposed on the bottom surface of pads 2822. The contact balls 2822 serve as contact structures disposed on the bottom surface of the support substrate 2808 to contact corresponding pads or terminals 2818 on PCB 2810. Other electrical contact structures may also be used.
Socket 2800 also includes a frame 2806 that is attached to PCB 2802. Frame 2806 includes landings 2826 to support package 2804. Socket 2800 also includes retaining means 2802 that is disposed over frame 2826 and package 2804. Retaining means 2802 retains package 2804 on landings 2826 such that spring contact elements 2816 remain in electrical contact with pads 2812 and 2814. Any suitable mechanical means may be used for retaining means 2802 including, for example, a spring clip.
In the foregoing specification the invention has been described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense.
This is a divisional application of Ser. No. 09/224,169, filed Dec. 31, 1998 now U.S. Pat. No. 6,456,099.
Number | Name | Date | Kind |
---|---|---|---|
3781683 | Freed | Dec 1973 | A |
3821645 | Vinsani | Jun 1974 | A |
3842189 | Southgate | Oct 1974 | A |
3849872 | Hubacher | Nov 1974 | A |
4281449 | Ports et al. | Aug 1981 | A |
4523144 | Okubo et al. | Jun 1985 | A |
4567433 | Ohkubo et al. | Jan 1986 | A |
4636722 | Ardezzone | Jan 1987 | A |
4719417 | Evans | Jan 1988 | A |
4837622 | Whann et al. | Jun 1989 | A |
4965865 | Trenary | Oct 1990 | A |
4983907 | Crowley | Jan 1991 | A |
5012187 | Littlebury | Apr 1991 | A |
5055778 | Okubo et al. | Oct 1991 | A |
5088190 | Malhi et al. | Feb 1992 | A |
5103557 | Leedy | Apr 1992 | A |
5106309 | Matsuoka et al. | Apr 1992 | A |
5123850 | Elder et al. | Jun 1992 | A |
5124639 | Carlin et al. | Jun 1992 | A |
5124646 | Shiraishi | Jun 1992 | A |
5172050 | Swapp | Dec 1992 | A |
5194932 | Kurisu | Mar 1993 | A |
5373231 | Boll et al. | Dec 1994 | A |
5395253 | Crumly | Mar 1995 | A |
5399982 | Driller et al. | Mar 1995 | A |
5404099 | Sahara | Apr 1995 | A |
5406210 | Pedder | Apr 1995 | A |
5418471 | Kardos | May 1995 | A |
5422574 | Kister | Jun 1995 | A |
5437556 | Bargain et al. | Aug 1995 | A |
5440231 | Sugai | Aug 1995 | A |
5442282 | Rostoker et al. | Aug 1995 | A |
5476211 | Khandros | Dec 1995 | A |
5491426 | Small | Feb 1996 | A |
5497079 | Yamada et al. | Mar 1996 | A |
5506499 | Puar | Apr 1996 | A |
5521518 | Higgins | May 1996 | A |
5525545 | Grube et al. | Jun 1996 | A |
5539325 | Rostoker et al. | Jul 1996 | A |
5541525 | Wood et al. | Jul 1996 | A |
5554940 | Hubacher | Sep 1996 | A |
5555422 | Nakano | Sep 1996 | A |
5573435 | Grabbe et al. | Nov 1996 | A |
5613861 | Smith et al. | Mar 1997 | A |
5629137 | Leedy | May 1997 | A |
5648661 | Rostoker et al. | Jul 1997 | A |
5677566 | King et al. | Oct 1997 | A |
5682064 | Atkins et al. | Oct 1997 | A |
5713744 | Laub | Feb 1998 | A |
5714803 | Queyssac | Feb 1998 | A |
5729150 | Schwindt | Mar 1998 | A |
5742170 | Isaac et al. | Apr 1998 | A |
5764072 | Kister | Jun 1998 | A |
5772451 | Dozier et al. | Jun 1998 | A |
5783461 | Hembree | Jul 1998 | A |
5786701 | Pedder | Jul 1998 | A |
5789930 | Isaacs et al. | Aug 1998 | A |
5807104 | Ikeya et al. | Sep 1998 | A |
5828226 | Higgins et al. | Oct 1998 | A |
5838163 | Rostoker et al. | Nov 1998 | A |
5863814 | Alcoe et al. | Jan 1999 | A |
5917707 | Khandros et al. | Jun 1999 | A |
5923178 | Higgins et al. | Jul 1999 | A |
5932891 | Higashi et al. | Aug 1999 | A |
5974662 | Eldridge et al. | Nov 1999 | A |
5983493 | Eldridge et al. | Nov 1999 | A |
5998228 | Eldridge et al. | Dec 1999 | A |
5998864 | Khandros et al. | Dec 1999 | A |
6002266 | Briggs et al. | Dec 1999 | A |
6008061 | Kasai | Dec 1999 | A |
6022750 | Akram et al. | Feb 2000 | A |
6023103 | Chang et al. | Feb 2000 | A |
6031282 | Jones et al. | Feb 2000 | A |
6050829 | Eldridge et al. | Apr 2000 | A |
6054334 | Ma | Apr 2000 | A |
6064213 | Khandros et al. | May 2000 | A |
6078083 | Amerasekera et al. | Jun 2000 | A |
6080604 | Waki | Jun 2000 | A |
6107111 | Manning | Aug 2000 | A |
6150827 | Pavoni et al. | Nov 2000 | A |
6204074 | Bertolet et al. | Mar 2001 | B1 |
6211541 | Carroll et al. | Apr 2001 | B1 |
6215454 | Tran | Apr 2001 | B1 |
6246250 | Doherty et al. | Jun 2001 | B1 |
6373143 | Bell | Apr 2002 | B1 |
6445001 | Yoshida | Sep 2002 | B2 |
20040004216 | Eldridge et al. | Jan 2004 | A1 |
Number | Date | Country |
---|---|---|
3-65659 | Mar 1991 | JP |
4-207047 | Jul 1992 | JP |
5-29406 | Feb 1993 | JP |
Number | Date | Country | |
---|---|---|---|
20010020747 A1 | Sep 2001 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 09224169 | Dec 1998 | US |
Child | 09753309 | US |