# Patent

## Title
Method and apparatus for RFID tag testing

## Abstract

A semiconductor wafer includes a plurality of dies and at least one test probe. Each of the plurality of dies includes a radio frequency identification (RFID) tag circuit. The at least one test probe includes a plurality of probe pads. The plurality of probe pads is configured to transmit power signals and data to each of the plurality of dies, and to receive test results from each of the plurality of dies. The data are transmitted to each of the plurality of dies in a serial manner. The test results of each of the plurality of dies are also transmitted to the plurality of probe pads in a serial manner.

## Background
This application claims the benefit of U.S. Provisional Application Ser. No. 61/693,127, filed on Aug. 24, 2012, entitled Method and Apparatus of RFID Tag Testing,” which application is hereby incorporated herein by reference.


FIELD OF DISCLOSURE
The present disclosure is related to radio frequency identification (RFID) and, more particularly, to RFID tag wafer testing.
BACKGROUND
Radio frequency identification (RFID) tags are used increasingly in a wide variety of applications. For example, RFID tags are used in conjunction with security-locks in cars, for access control to buildings, for tracking inventory and parcels, etc.
RFID tags are used to associate an object with an identification code. RFID tags generally have a combination of antennas and analog and/or digital electronics, which may include, for example, communications electronics, data memory, control logics, etc.
RFID tags do not include a power source however. In order to retrieve information from a chip, a “base station” or “reader” sends an excitation signal to an RFID tag. The excitation signal energizes the RFID tag, and the RFID tag transmits the stored information back to the reader. The information includes environmental data, logistical histories, state data, etc. In general, RFID tags retain and transmit enough information to uniquely identify individuals, packages, inventory and the like.
One challenge associated with RFID tags is manufacturing and testing the RFID tags in a high-volume and cost-effective manner.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a system 100 of a wafer testing of RFID tags in accordance with some embodiments.
FIG. 2 illustrates a power signal transmission from the test probe 124 to each of the plurality of RFID dies 122 in a die fragment 200 of the RFID wafer 120 in FIG. 1 in accordance with some embodiments.
FIG. 3 is an enlarged plane view 300 of a region A in FIG. 2 to illustrate power transmission from the test probe 124 to each RFID die 122 in details in accordance with some embodiments.
FIG. 4 is a die fragment 400 of the RFID wafer 120 in FIG. 1 to illustrate the transmission of control and data signals from the test probe 124 to each of the plurality of RFID dies 122 in accordance with some embodiments.
FIG. 5 is a schematic of a RFID die 500 to illustrate details of the RFID dies 122 in FIGS. 1, 2, 3 and 4 in accordance with some embodiments.
FIG. 6 is a test probe 600 to illustrate details of the test probe 124 in FIGS. 1, 2, 3 and 4 in accordance with some embodiments.
FIG. 7 is a flow chart 700 of a wafer testing method of RFID tags in FIG. 1 in accordance with some embodiments.



DETAILED DESCRIPTION
Making and using various embodiments of the disclosure are discussed in detail below. It should be appreciated, however, that the embodiments provide many applicable inventive innovations that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative, and do not limit the scope of the disclosure.
Some embodiments have one or a combination of the following features and/or advantages. A semiconductor wafer includes a plurality of dies and at least one test probe. Each of the plurality of dies includes a radio frequency identification (RFID) tag circuit. The at least one test probe includes a plurality of probe pads. The plurality of probe pads is configured to transmit power signals and data to each of the plurality of dies, and to receive test results from each of the plurality of dies. The data are transmitted to each of the plurality of dies in a serial manner. The test results of each of the plurality of dies are also transmitted to the plurality of probe pads in a serial manner.
FIG. 1 is a system 100 of a wafer testing of RFID tags according to some example embodiments. The system 100 includes a test head 112 of a tester (not shown), a probe card 114, and a RFID wafer 120. A probe interface 118 is configured to connect the test head 112 and the probe card 114. A plurality of probe pins 116 are on the probe card 114. In some embodiments, the plurality of probe pins 116 are cantilever probes, Cobra needle probes, membrane bumps, and/or other compliant contact technologies. In a wafer test, test patterns that are specified by users in the tester are configured to convert into separated power signals, control signals, data signals and clock signals. The power signals, control signals, data signals and clock signals are transmitted from the tester to the plurality of probe pins 116 through the test head 112, probe interface 118 and the probe card 114. The RFID wafer 120 includes a plurality of RFID dies 122 and a test probe 124. For illustration purposes, only four RFID dies 122 are labeled. Each of the plurality of RFID dies includes an RFID tag circuit. The test probe 124 includes a plurality of probe pads (not shown). In a wafer test, the plurality of probe pins 116 physically touches the corresponding probe pads in the test probe 124 such that the control signals, data signals, clock signals and power signals on the plurality of probe pins 116 are transmitted to the plurality of probe pads in the test probe 124. The plurality of probe pads in the test probe 124 is electrically connected to corresponding RFID dies 122 such that the control signals, data signals, clock signal and power signals on the plurality of probe pads are transmitted to the specified RFID dies 122.
Although the RFID wafer 120 only has one test probe 124, other numbers of test probes 124 are within the scope of various embodiments. Although the test probe 124 is located at the center of the RFID wafer 120 in FIG. 1, other locations on the RFID wafer 120 are within the scope of various embodiments.
FIG. 2 illustrates a power signal transmission from the test probe 124 to each of the plurality of RFID dies 122 in a die fragment 200 of the RFID wafer 120 in FIG. 1 according to some example embodiments. The die fragment 200 includes a plurality of RFID dies 122, the test probe 124 and scribe regions 210. For illustration purposes, only four RFID dies 122, two conductive lines 220 and four scribe regions 210 are labeled. The plurality of RFID dies 122 and the test probe 124 are similar to the corresponding ones in FIG. 1. The scribe regions 210 are spaces in between the plurality of RFID dies 122 such that the RFID wafer 120 in FIG. 1 is cut into physically separated RFID dies 122 along the scribe region 210 without damaging the RFID dies 122. In some embodiments, a saw is configured to cut the RFID wafer 120 in FIG. 1 into physically separated RFID dies 122. In some embodiments, the saw is a water-cooled circular saw with diamond-tipped teeth. In some embodiments, the RFID wafer 120 in FIG. 1 is cut into physically separated RFID dies 122 using chemical etching process. In some embodiments, the RFID wafer 120 in FIG. 1 is cut into physically separated RFID dies 122 using laser scribing.
The power signals on the probe pads in the test probe 124 are transmitted to each of the plurality of RFID dies 122 through conductive lines 220 in the scribe regions 210 and power planes (not shown) in the RFID dies 122 and the test probe 124. At least one conductive line 220 is electrically connected between two adjacent RFID dies 122 or between test probe 124 and RFID dies 122 to transmit power signals. The conductive lines 220 are generated by conductive materials such as metal lines, Oxide Definition (OD), polysilicon (POLY), Redistribution Layer (RDL), and the like. A region A will be explained in details with reference to FIG. 3.
FIG. 3 is an enlarged plane view 300 of region A in FIG. 2 to illustrate power transmissions from the test probe 124 to each RFID die 122 in details, according to some example embodiments. FIG. 3 includes a plurality of RFID dies 122, the test probe 124 and the scribe regions 210. For illustration purposes, only four RFID dies 122 and four conductive lines 220 are labeled. The scribe regions 210 are similar to the ones described in FIG. 2. The test probe 124 includes power signal probe pads 342 and power planes 340. The power planes 340 are in a ring structure to have conductive lines surrounding the test probe 124. The power signal probe pads 342 are electrically connected to the power planes 340. The adjacent conductive lines 220 around the test probe 124 are electrically connected to the power planes 340. Each of the plurality of RFID dies 122 includes power planes 330. The power planes 330 are in a ring structure to have conductive lines surrounding each of the plurality of RFID dies 122. The power planes 330 of each of the plurality of RFID dies 122 are electrically connected to the adjacent conductive lines 220 around that RFID die. In this way, the power signals on the power signal probe pads 342 are transmitted to each of the plurality of RFID dies 122 through the power planes 340 in the test probe 124, the conductive lines 220 in the scribe regions 210 and the power planes 330 of the plurality of RFID dies 122.
In some embodiments, the power signal probe pads 342 in the test probe 124 include at least one VDD pad and at lease one ground pad, and the VDD pads and the ground pads are electrically connected to corresponding individual power planes 340 in the test probe 124. VDD refers operation power for RFID tag circuit in each of the plurality of RFID dies 122. For simplicity, only one power signal probe pad 342 and one power plane 340 in test probe 124 are shown and labeled in FIG. 3. In some embodiments, each of the plurality of RFID dies 122 includes at least one power plane for VDD and at least one power plane for ground. For simplicity, only one power plane 330 is shown in each of the plurality of RFID dies 122, and only one power plane 330 is labeled in FIG. 3. The power planes 340 for VDD in the test probe 124 are electrically connected to the power planes 330 for VDD in adjacent RFID dies 122 through corresponding conductive lines 220 for VDD. The power planes 340 for ground in the test probe 124 are electrically connected to the power planes 330 for ground in adjacent RFID dies 122 through corresponding conductive lines 220 for ground.
Although the power planes 330 and 340 in FIG. 3 are in a ring structure, other structures of the power planes 330 and 340 are within the scope of various embodiments. For example, the power planes 330 and 340 in FIG. 3 are in a mesh structure. In some embodiments, the test probe 124 and the plurality of RFID dies 122 include different structures of power planes. For example, the power planes 340 of the test probe 124 are in a mesh structure and the power planes 330 of the plurality of RFID dies 122 are in ring structure, and vice versa. In some embodiments, the power planes 330 and 340 are generated by conductive materials such as metal lines, Oxide Definition (OD), polysilicon (POLY), Redistribution Layer (RDL), and the like.
FIG. 4 is a die fragment 400 of the RFID wafer 120 in FIG. 1 to illustrate the transmission of control and data signals from the test probe 124 to each of the plurality of RFID dies 122 in a according to some example embodiments. The die fragment 400 includes a plurality of RFID dies 122, the test probe 124 and the scribe regions 210. For illustration purposes, only four RFID dies 122 and five scribe regions 210 are labeled. The plurality of RFID dies 122 in the die fragment 400 are divided into four shifting chains 410, 430, 450 and 470. The RFID dies in the same shifting chain are electrically and serially connected by conductive lines in the scribe regions 210. For example, in shifting chain 410, RFID dies D411-D422 are electrically and serially connected by conductive lines 412-422, respectively. The conductive lines in the scribe regions 210 are generated by conductive materials such as metal lines, Oxide Definition (OD), polysilicon (POLY), Redistribution Layer (RDL), and the like. The control and data signals that are configured to test functionalities of RFID dies in a wafer test are transmitted from probe pads (not shown) in the test probe 124 to each of RFID dies in the same shifting chain in a serial manner.
For example, in the shifting chain 410, the control and data signals that are configured to test functionalities of RFID die D413 in a wafer test are serially transmitted from the probe pads in the test probe 124 through conductive lines 411, RFID die D411, conductive lines 412, RFID die D412, and conductive lines 413 to RFID die D413. For another example, the testing results of RFID die D420 are serially transmitted through conductive lines 421, RFID die D421, conductive lines 422, RFID die D422, and conductive lines 423 to the probe pads in the test probe 124.
For example, in the shifting chain 430, the control and data signals that are configured to test functionalities of RFID die D433 in a wafer test are serially transmitted from the probe pads in the test probe 124 through conductive lines 431, RFID die D431, conductive lines 432, RFID die D432, and conductive lines 433 to RFID die D433. For another example, the testing results of RFID die D440 are serially transmitted through conductive lines 441, RFID die D441, conductive lines 442, RFID die D442, and conductive lines 443 to the probe pads in the test probe 124.
For example, in the shifting chain 450, the control and data signals that are configured to test functionalities of RFID die D453 in a wafer test are serially transmitted from the probe pads in the test probe 124 through conductive lines 451, RFID die D451, conductive lines 452, RFID die D452, and conductive lines 453 to RFID die D453. For another example, the testing results of RFID die D460 are serially transmitted through conductive lines 461, RFID die D461, conductive lines 462, RFID die D462, and conductive lines 463 to the probe pads in the test probe 124.
For example, in the shifting chain 470, the control and data signals that are configured to test functionalities of RFID die D473 in a wafer test are serially transmitted from the probe pads in the test probe 124 through conductive lines 471, RFID die D471, conductive lines 472, RFID die D472, and conductive lines 473 to RFID die D473. For another example, the testing results of RFID die D480 are serially transmitted through conductive lines 481, RFID die D481, conductive lines 482, RFID die D482, and conductive lines 483 to the probe pads in the test probe 124.
Although the plurality of RFID dies 122 in the die fragment 400 are divided into four shifting chains 410, 430, 450 and 470, another number of the shifting chains is within the scope of various embodiments.
FIG. 5 is a schematic of an RFID die 500 to illustrate details of the RFID dies 122 in FIGS. 1, 2, 3 and 4 according to some example embodiments. The RFID die 500 includes a RFID tag circuit 510, a comparator 520, control signal shift registers 530, data signal shift registers 540 and AND gates 550 and 552. The power planes 330 in FIG. 3 are omitted in FIG. 5 for ease of illustration. The control signals that are configured to control testing of the RFID tag circuit 510 in the wafer test are shifted into the control signal shift registers 530 through conductive lines 562. Contents in the control signal shift registers 530 are shifted out through conductive lines 564. The control signals in the control signal shift registers 530 includes a command gated signal and a comparison start signal. The data signals that are configured to test the RFID tag circuit 510 in the wafer test are shifted into the data signal shift registers 540 through conductive lines 566. Contents of the data signal shift registers 540 are shifted out through conductive lines 568. The data in the data signal shift registers 540 includes test patterns, expected results of current test patterns and comparison results.
The conductive lines 562 of the current RFID die are electrically connected to the conductive lines 564 of previous RFID die in sequence in the same shifting chain or to the test probe 124 in FIG. 4. The conductive lines 564 of current RFID die are electrically connected to the conductive lines 562 of following RFID die in sequence in the same shifting chain or to the test probe 124 in FIG. 4. For example, in the shifting chain 410 in FIG. 4, the conductive lines 562 in FIG. 5 of the RFID die D412 in FIG. 4 are electrically connected to the conductive lines 564 in FIG. 5 of the RFID die D411 in FIG. 4 through conductive lines 412 in FIG. 4. The conductive lines 564 in FIG. 5 of the RFID die D412 in FIG. 4 are electrically connected to the conductive lines 562 of the RFID die D413 in FIG. 4 through the conductive lines 413 in FIG. 4. The conductive lines 562 in FIG. 5 of the RFID die D411 in FIG. 4 are electrically connected to the probe pads in the test probe 124 such that the control signals on the probe pads are configured to shift into the control signal shift registers 530 in FIG. 5 of the RFID die D411 in FIG. 4. The conductive lines 564 in FIG. 5 of the RFID die D422 in FIG. 4 are electrically connected to the probe pads in the test probe 124 such that the contents of the control signal shift registers 530 are configured to shift out to the probe pads in the test probe 124 in FIG. 4.
The conductive lines 566 of the current RFID die are electrically connected to the conductive lines 568 of previous RFID die in sequence in the same shifting chain or to the test probe 124 in FIG. 4. The conductive lines 568 of current RFID die are electrically connected to the conductive lines 566 of following RFID die in sequence in the same shifting chain or to the test probe 124 in FIG. 4. For example, in the shifting chain 410 in FIG. 4, the conductive lines 566 in FIG. 5 of the RFID die D412 in FIG. 4 are electrically connected to the conductive lines 568 in FIG. 5 of the RFID die D411 in FIG. 4 through conductive lines 412 in FIG. 4. The conductive lines 568 in FIG. 5 of the RFID die D412 in FIG. 4 are electrically connected to the conductive lines 566 of the RFID die D413 in FIG. 4 through the conductive lines 413 in FIG. 4. The conductive lines 566 in FIG. 5 of the RFID die D411 in FIG. 4 are electrically connected to the probe pads in the test probe 124 such that the data signals on the probe pads are configured to shift into the data signal shift registers 540 in FIG. 5 of the RFID die D411 in FIG. 4. The conductive lines 568 in FIG. 5 of the RFID die D422 in FIG. 4 are electrically connected to the probe pads in the test probe 124 such that the contents of the data signal shift registers 540 are configured to shift out to the probe pads in the test probe 124 in FIG. 4.
A clock signal on a conductive line 560 is electrically connected to an input port of the AND gate 550. The test patterns in the data signal shift registers 540 are transmitted through conductive lines 542 to inputs of the AND gates 552. The command gated signal in the control signal shift registers 530 is electrically connected to inputs of each of the AND gates 550 and 552 through a conductive line 532. The command gated signal is configured to decide when the clock signal on the conductive line 560 and the test patterns on the conductive lines 542 are transmitted to the RFID tag circuit 510. When the command gated signal is “0”, the clock signal on the conductive line 560 and the test patterns on the conductive lines 542 are blocked at the AND gates 550 and 552 as the outputs of the AND gates 550 and 552 are set to a constant value “0”. When the command gated signal is “1”, the clock signal on the conductive line 560 is transmitted through conductive line 554 to the RFID tag circuit 510, the test patterns on the conductive lines 542 are transmitted through conductive lines 556 to the RFID tag circuit 510. Although the AND gates 550 and 552 are used in FIG. 5, other logical gates, such as OR, NAND, NOR, XOR, XNOR gates, are within the scope of various embodiments.
The expected results of current test patterns in the data signal shift registers 540 are transmitted through conductive lines 544 to the comparator 520. After receiving test patterns from the conductive lines 556, the RFID tag circuit 510 outputs the execution results through conductive lines 512 to the comparator 520. The comparison start signal in the control signal shift registers 530 is electrically connected to the comparator 520 through a conductive line 534. The comparison start signal is configured to decide when the comparison in the comparator 520 between the execution results of the RFID tag circuit 510 and the expected results of current test patterns in the data signal shift registers 540 is started. When the comparison start signal on the conductive line 534 is “1”, the comparison in the comparator 520 between the execution results of the RFID tag circuit 510 and the expected results of current test patterns on the conductive lines 544 is started, and the comparison results are outputted from the comparator 520 and written into the data signal shift registers 540 through conductive lines 546.
FIG. 6 is a test probe 600 to illustrate details of the test probe 124 in FIGS. 1, 2, 3 and 4 according to some example embodiments. The test probe 600 includes probe pads 611-615, 631-635, 651-655, 671-675, the power planes 340 and the power signal probe pads 342. The power planes 340 and the power signal probe pads 342 are similar to the corresponding ones described in FIG. 3. The power signals on the power signal probe pads 342 are transmitted through the power planes 340 and the conductive lines 220 to each of the plurality of RFID dies 122 in FIG. 3. In some embodiments, the power signal probe pads 342 in the test probe 600 include at least one VDD pad and at lease one ground pad. Each of the VDD and the ground pads in the test probe 600 is electrically connected to corresponding power planes 340, and the power planes 340 are electrically connected to adjacent RFID dies through corresponding conductive lines 220.
The probe pads 611, 631, 651, 671 are electrically connected to each of the RFID dies in the shifting chains 410, 430, 450 and 470 in FIG. 4, respectively, through the conductive lines 621, 641, 661 and 681, respectively, and are configured to transmit the clock signal as described in FIG. 4 and FIG. 5. For example, the clock signal on the probe pads 611 is transmitted through the conductive lines 621 to each of the RFID dies in the shifting chains 410 in FIG. 4.
The probe pad 612 is electrically connected to the conductive lines 562 in FIG. 5 of the RFID die D411 in the shifting chain 410 in FIG. 4 such that the control signals on the probe pad 612 are configured to serially shift into the control signal shift registers 530 in FIG. 5 of the RFID dies in the shifting chain 410 in FIG. 4. The probe pad 613 is electrically connected to the conductive lines 564 in FIG. 5 of the RFID die D422 in the shifting chain 410 in FIG. 4 to receive the shift out data of the control signal shift registers 530 in FIG. 5 of the RFID die D422 in the shifting chain 410 in FIG. 4.
The probe pad 614 is electrically connected to the conductive lines 566 in FIG. 5 of the RFID die D411 in the shifting chain 410 in FIG. 4 such that the data signals on the probe pad 614 are configured to serially shift into the data signal shift registers 540 in FIG. 5 of the RFID dies in the shifting chain 410 in FIG. 4. The probe pad 615 is electrically connected to the conductive lines 568 in FIG. 5 of the RFID die D422 in the shifting chain 410 in FIG. 4 to receive the shift out data of the data signal shift registers 540 in FIG. 5 of the RFID die D422 in the shifting chain 410 in FIG. 4.
The probe pad 632 is electrically connected to the conductive lines 562 in FIG. 5 of the RFID die D431 in the shifting chain 430 in FIG. 4 such that the control signals on the probe pad 632 are serially configured to shift into the control signal shift registers 530 in FIG. 5 of the RFID dies in the shifting chain 430 in FIG. 4. The probe pad 633 is electrically connected to the conductive lines 564 in FIG. 5 of the RFID die D442 in the shifting chain 430 in FIG. 4 to receive the shift out data of the control signal shift registers 530 in FIG. 5 of the RFID die D442 in the shifting chain 430 in FIG. 4.
The probe pad 634 is electrically connected to the conductive lines 566 in FIG. 5 of the RFID die D431 in the shifting chain 430 in FIG. 4 such that the data signals on the probe pad 634 are configured to serially shift into the data signal shift registers 540 in FIG. 5 of the RFID dies in the shifting chain 430 in FIG. 4. The probe pad 635 is electrically connected to the conductive lines 568 in FIG. 5 of the RFID die D442 in the shifting chain 430 in FIG. 4 to receive the shift out data of the data signal shift registers 540 in FIG. 5 of the RFID die D442 in the shifting chain 430 in FIG. 4.
The probe pad 652 is electrically connected to the conductive lines 562 in FIG. 5 of the RFID die D451 in the shifting chain 450 in FIG. 4 such that the control signals on the probe pad 652 are configured to serially shift into the control signal shift registers 530 in FIG. 5 of the RFID dies in the shifting chain 450 in FIG. 4. The probe pad 653 is electrically connected to the conductive lines 564 in FIG. 5 of the RFID die D462 in the shifting chain 450 in FIG. 4 to receive the shift out data of the control signal shift registers 530 in FIG. 5 of the RFID die D462 in the shifting chain 450 in FIG. 4.
The probe pad 654 is electrically connected to the conductive lines 566 in FIG. 5 of the RFID die D451 in the shifting chain 450 in FIG. 4 such that the data signals on the probe pad 654 are configured to serially shift into the data signal shift registers 540 in FIG. 5 of the RFID dies in the shifting chain 450 in FIG. 4. The probe pad 655 is electrically connected to the conductive lines 568 in FIG. 5 of the RFID die D462 in the shifting chain 450 in FIG. 4 to receive the shift out data of the data signal shift registers 540 in FIG. 5 of the RFID die D462 in the shifting chain 450 in FIG. 4.
The probe pad 672 is electrically connected to the conductive lines 562 in FIG. 5 of the RFID die D471 in the shifting chain 470 in FIG. 4 such that the control signals on the probe pad 672 are configured to serially shift into the control signal shift registers 530 in FIG. 5 of the RFID dies in the shifting chain 470 in FIG. 4. The probe pad 673 is electrically connected to the conductive lines 564 in FIG. 5 of the RFID die D482 in the shifting chain 470 in FIG. 4 to receive the shift out data of the control signal shift registers 530 in FIG. 5 of the RFID die D482 in the shifting chain 470 in FIG. 4.
The probe pad 674 is electrically connected to the conductive lines 566 in FIG. 5 of the RFID die D471 in the shifting chain 470 in FIG. 4 such that the data signals on the probe pad 674 are configured to serially shift into the data signal shift registers 540 in FIG. 5 of the RFID dies in the shifting chain 470 in FIG. 4. The probe pad 675 is electrically connected to the conductive lines 568 in FIG. 5 of the RFID die D482 in the shifting chain 470 in FIG. 4 to receive the shift out data of the data signal shift registers 540 in FIG. 5 of the RFID die D482 in the shifting chain 470 in FIG. 4.
FIG. 7 illustrates a flow chart 700 of a wafer testing method of RFID tags in FIG. 1 according to some example embodiments.
In step 710, the power signals on the probe pads 342 in FIG. 6 are transmitted to each of the plurality of RFID dies 122 in the RFID wafer 120 in FIG. 1. For example, in FIG. 3, the power signals on the probe pads 342 are transmitted through the power planes 340 in the test probe 124, the conductive lines 220 in the scribe regions 210 and the power planes 330 in the RFID dies 122 to each of the plurality of RFID dies 122.
In step 720, the control and data signals on the probe pads 612, 614, 632, 634, 652, 654, 672, 674, respectively, in FIG. 6 are transmitted to each of RFID dies 122 in FIG. 4 in the same shifting chain in a serial manner. For example, in the shifting chain 410 in FIG. 4, the control signals on the probe pads 612 in FIG. 6 are transmitted through conductive lines 411 in FIG. 4, the control signal shift registers 530 in FIG. 5 of RFID die D411 in FIG. 4, conductive lines 412 in FIG. 4, the control signal shift registers 530 in FIG. 5 of RFID die D412 in FIG. 4 and conductive lines 413 in FIG. 4 to the control signal shift registers 530 in FIG. 5 of RFID die D413 in FIG. 4 in a serial manner.
For example, in the shifting chain 410 in FIG. 4, the data signals on the probe pads 614 in FIG. 6 are transmitted through conductive lines 411 in FIG. 4, the data signal shift registers 540 in FIG. 5 of RFID die D411 in FIG. 4, conductive lines 412 in FIG. 4, the data signal shift registers 540 in FIG. 5 of RFID die D412 in FIG. 4 and conductive lines 413 in FIG. 4 to the data signal shift registers 540 in FIG. 5 of RFID die D413 in FIG. 4 in a serial manner.
In step 730, the comparison results in the data signal shift registers 540 of each of the RFID dies in the same shifting chain are transmitted to probe pads 615, 635, 655, 675 respectively of the test probe 124 in FIG. 6 in a serial manner. For example, in the shifting chain 410 in FIG. 4, the comparison results in the data signal shift registers 540 in FIG. 5 of RFID die D420 in FIG. 4 are transmitted through conductive lines 421 in FIG. 4, the data signal shift registers 540 in FIG. 5 of RFID die D421 in FIG. 4, conductive lines 422 in FIG. 4, the data signal shift registers 540 in FIG. 5 of RFID die D422 in FIG. 4, conductive lines 423 in FIG. 4 to the probe pads 615 in FIG. 6.
In some embodiments, a semiconductor wafer includes a plurality of dies and at least one test probe. Each of the plurality of dies includes a radio frequency identification (RFID) tag circuit. The at least one test probe includes a plurality of probe pads. The plurality of probe pads is configured to transmit power signals and data to each of the plurality of dies, and to receive test results from each of the plurality of dies. The data are transmitted to each of the plurality of dies in a serial manner. The test results of each of the plurality of dies are transmitted to the plurality of probe pads in a serial manner.
In some embodiments, a system for testing radio frequency identification on (RFID) tags includes a probe card and a wafer. The probe card includes a plurality of probe pins. The wafer includes a plurality of dies and at least one test probe. Each of the plurality of dies includes a RFID tag circuit. The at least one test probe includes a plurality of probe pads. The plurality of probe pads is configured to transmit power signals and data to each of the plurality of dies, and to receive test results from each of the plurality of dies. The plurality of dies and the at least one test probe include power planes to transmit power signals to adjacent dies.
In some embodiments, a method of configuring a wafer testing of radio frequency identification (RFID) tags includes transmitting power signals to each of a plurality of dies from probe pads of a test probe. The method also includes transmitting control and data signals to each of dies in the same shifting chain in a serial manner from probe pads of the test probe. The method further includes transmitting testing results of each of the dies in the same shifting chain in a serial manner to probe pads of the test probe.
While the disclosure has been described by way of examples and in terms of disclosed embodiments, the invention is not limited to the examples and disclosed embodiments. To the contrary, various modifications and similar arrangements are covered as would be apparent to those of ordinary skill in the art. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass such modifications and arrangements.

## Claims

1. A system for testing radio frequency identification (RFID) tags, comprising:
a probe card includes a plurality of probe pins; and
a wafer comprising
a plurality of dies, each of the plurality of dies includes a RFID tag circuit; and
at least one test probe including a plurality of probe pads;

wherein
the plurality of probe pads is configured to transmit power signals and data to each of the plurality of dies, and to receive test results from each of the plurality of dies; and
the plurality of dies and the at least one test probe include power planes to transmit power signals to adjacent dies;
a data signal serial chain configured to transmit data signals from the test probe to a first die data input and from an first die data output to a second die data input continuing until the data signals are serially transmitted to each die of the plurality of dies; and
a control signal serial chain configured to transmit control signals from the test probe to a first die control input and from a first die control output to a second die control input continuing until the control signals are serially transmitted to each die of the plurality of dies.

2. The system of claim 1, wherein the power signals and data are transmitted to each of the plurality of dies, and the test results are transmitted to the plurality of probe pads, through conductive lines in scribe regions.

3. The system of claim 2, wherein the test results are generated by comparing execution results of each of the plurality of dies with expected results in data signal shift registers of corresponding dies.

4. The system of claim 1, wherein the data are transmitted to each of the plurality of dies, and the test results of each of the plurality of dies are transmitted to the plurality of probe pads in a serial manner.

5. The system of claim 1, wherein the power planes in the plurality of dies and the test probe include at least one VDD plane and at least one ground plane.

6. The system of claim 1, wherein each of the plurality of dies includes control signal shift registers and data signal shift registers to store control and data signals respectively that are configured to test a corresponding RFID tag circuit.

7. The system of claim 1, wherein inputs of control signal shift registers and data signal shift registers of one of the plurality of dies are electrically connected to outputs of control signal shift registers and data signal shift registers respectively of previous dies in the same shifting chain; and
outputs of the control signal shift registers and the data signal shift registers of the one of the plurality of dies are electrically connected to inputs of the control signal shift registers and the data signal shift registers respectively of following dies in the same shifting chain.

8. A method of configuring a wafer testing of radio frequency identification (RFID) tags, comprising:
transmitting power signals to each of a plurality of dies from probe pads of a test probe;
serially transmitting control and data signals to each of dies in the same shifting chain from probe pads of the test probe; and
serially transmitting testing results of each of the dies in the same shifting chain to a plurality of probe pads of the test probe.

9. The method of claim 8, wherein the power signals and data signals are transmitted to each of the plurality of dies, and the test results of each of the plurality of dies are transmitted to the plurality of probe pads, through conductive lines in scribe regions.

10. The method of claim 8, wherein the test results are generated by comparing execution results of each of the plurality of dies with expected results in data signal shift registers of corresponding dies.

11. The method of claim 8, wherein the plurality of dies and the test probe includes power planes to transmit power signals to adjacent dies.

12. The method of claim 11, wherein the power planes in the plurality of dies and the test probe include at least one VDD plane and at least one ground plane.

13. The method of claim 8, wherein each of the plurality of dies includes control signal shift registers and data signal shift registers to store control and data signals respectively that are configured to test corresponding RFID tag circuits.

14. A method for testing radio frequency identification (RFID) tags, comprising:
connecting to a test head a probe card;
aligning to the probe card a wafer, the wafer including
a plurality of RFID tag circuit die, the plurality of RFID tag circuit die being arranged in a plurality of shifting chains;
a test probe including a plurality of probe pads and a power plane;
a first scribe region interjacent the test probe and respective shifting chains;

second scribe regions interjacent respective RFID tag circuit die within the respective shifting chains;
power conductive lines in the first scribe region, each power conductive line connecting the test probe with a respective plane;

a second power conductive line within each second scribe region, each second power conductive line connecting the respective RFID tag circuit die within a second respective plane;
outgoing signal lines in the first scribe region, each outgoing signal line connecting the test probe with a respective shifting chain;
at least one second outgoing signal line within each second scribe region, each second outgoing signal line serially connecting the respective RFID tag circuit die within a respective shifting chain;
incoming signal lines in the first scribe region, each incoming signal line connecting the test probe with a respective shifting chain;
at least one second incoming signal line within each second scribe region, each second incoming signal line serially connecting the respective RFID tag circuit die within a respective shifting chain;
applying power to the respective RFID tag circuit die through the power conductive lines and the second power conductive lines;
applying test signals to the respective RFID tag circuit die through the outgoing signal lines and at least one second outgoing signal lines; and
receiving results from the respective RFID tag circuit die through the incoming signal lines and at least one second incoming signal lines.

15. The method of claim 14, further comprising singulating the respective RFID tag circuit die along the first and second scribe regions.

16. The method of claim 14, further comprising comparing execution results from the respective RFID tag circuit die with expected results.

17. The method of claim 14, further comprising aligning probes on the probe card to pads on the test probe.

18. The method of claim 14, wherein control signals are sent simultaneously to each shifting chain and are transmitted serially to each RFID tag circuit die within a respective shifting chain.

19. The method of claim 16, further comprising transmitting the results of the comparing step to the test probe.

20. The method of claim 14, further comprising shifting the test signals into control shift registers within the respective RFID tag circuit die.