EDGE DETECTION SYSTEM

Abstract

A method for detecting edge cracks in a tested chip (130), comprising: receiving a command signal (111) by means of an antenna (122) of an RFID transponder (120), wherein the antenna (122) surrounds the chip (130); supplying energy from the command signal (111); supplying a response signal (121) based on the command signal (111) by means of the antenna (122) of the RFID transponder (120); and performing a self-destruction of the RFID transponder (120) based on the command signal (111).

Description

BACKGROUND Edge cracks often form on chips during the sawing process. A traditional method for edge crack detection is visual inspection, which, however, cannot be performed at the wafer level after the packaging process, such as tape and reel (TnR). Therefore, there is a need to develop new methods for edge crack detection. US Patent 2012 / 0199948A1 describes a semiconductor chip with a protective layer designed to prevent the chip from being read by physical tampering. Within the protective layer are several capacitors connected in parallel to a control unit. The control unit is designed to detect a short circuit in a capacitor or an open circuit in a lead and, in this case, generate a warning signal. The semiconductor chip may self-destruct if a warning signal is generated. JP 2000-208709 A discloses a circuit board with an integrated circuit and an antenna. The circuit is powered via the antenna and can exchange data. The circuit also includes a resistance wire and is configured to determine the wire's resistance. If the resistance exceeds a predefined threshold, this is interpreted as an indication of circuit damage, and the circuit is deactivated. German patent DE 10 2012 209 148 A1 discloses an RFID tag comprising an RFID chip for processing data, an antenna for transmitting the data, and a security device. The security device is designed to destroy the RFID chip during a predetermined use of the device, thus protecting the RFID tag from unauthorized reuse. BRIEF DESCRIPTION OF THE DRAWINGS Aspects of this disclosure are best understood with reference to the following detailed description, when read in conjunction with the accompanying figures. It should be noted that, in accordance with common industry practice, various structural elements are not drawn to scale. The dimensions of illustrated structural elements may be enlarged or reduced as necessary for the clarity of the discussion. Fig. 1 is a block diagram illustrating an exemplary edge crack detection system according to some embodiments. Fig. 2 is a flowchart for a method of detecting edge cracks in a chip under test according to some embodiments. Fig. 3 is a flowchart for a method of detecting edge cracks in a chip under test according to some embodiments.Figure 4 is a block diagram illustrating a wafer containing chips that have the exemplary RFID transponder, according to some embodiments. Figure 5 is a block diagram illustrating the exemplary edge crack detection system using a tape-and-reel package, according to some embodiments. Figure 6 is a block diagram illustrating another exemplary RFID transponder, according to some embodiments. DETAILED DESCRIPTION The following disclosure provides many different embodiments or examples for implementing various features of the invention. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, only examples and are not intended to be limiting. For example, the formation of a first structural element above or on top of a second structural element in the following description may include embodiments in which the first and second structural elements are in direct contact, and may also include embodiments in which additional structural elements may be formed between the first and second structural elements, so that the first and second structural elements are not necessarily in direct contact. Furthermore, the present disclosure may repeat reference numerals and / or letters in the various examples.This repetition serves the purpose of simplicity and clarity and does not automatically create a relationship between the various designs and / or configurations discussed. Furthermore, spatially relative terms, such as "below," "under," "lower," "above," "upper," and the like, may be used in this text to simplify the description and to describe the relationship of one element or structural element to one or more other elements or structural elements, as illustrated in the figures. These spatially relative terms are intended to encompass not only the orientation shown in the figures but also other orientations of the device during use or operation. The device may also be oriented differently (rotated 90 degrees or otherwise), and the spatially relative descriptors used in this text may be interpreted accordingly. The disclosure describes a method that uses an RFID reader and an RFID transponder to detect edge cracks in a chip under test. The RFID transponder comprises a transponder antenna and a transponder processor. The transponder processor is located beneath a sealing ring of the chip. The transponder antenna is located outside the chip's sealing ring. The RFID reader sends a command signal to the RFID transponder. If the chip under test has no edge cracks, the transponder antenna and the transponder processor surrounding the chip under test send a response signal to the RFID reader. That is, upon receiving the response signal, the RFID reader determines that the chip under test has no edge cracks.Furthermore, after determining that the chip has no edge cracks, the RFID reader sends a self-destruct command to destroy or disable the RFID transponder, so the procedure has no impact on the chip's normal operation. If edge cracks occur that damage the tested chip, the transponder antenna, or the transponder processor, the RFID reader will not be able to receive a response signal. More precisely, the process can include the following operations: the transponder antenna converts between electromagnetic wave and electrical signal; the transponder processor outputs a response signal through the transponder antenna; the RFID reader receives the response signal; if the transponder antenna is not working, the RFID reader does not receive a signal from the RFID transponder; if the RFID reader receives the response signal from the RFID transponder, the RFID reader sends a self-destruct command to cause the RFID transponder to self-destruct. The edge crack detection system can be applied to any RF band, for example: Low Frequency (LF) at 120-135 kHz; High Frequency (HF) at 13.56 MHz; Ultra High Frequency (UHF) at 433 MHz or 860-960 MHz; and Microwave at 2450 MHz. Fig. 1 is a block diagram illustrating an exemplary edge crack detection system according to some embodiments. As shown in Fig. 1, a system 100 is provided. The system 100 comprises an RFID reader 110 and an RFID transponder 120, which is wirelessly connected to the RFID reader 110. The RFID transponder 120 is physically connected to a tested chip 130. The RFID transponder 120 can include an antenna 122 located outside the sealing ring 131 of the chip 130. The antenna 122 can have a width of 1 micrometer. The RFID transponder 120 can also include a processor 124 located under a sealing ring 131 of the chip 130. The processor 124 can have a width of 10 micrometers and a length of 500 micrometers. The RFID reader 110 outputs a command signal 111. The RFID transponder 120 receives the command signal 111. The RFID transponder 120 generates energy from the command signal 111 and outputs a response signal 121 based on the command signal 111. The RFID reader 110 receives the response signal 121, thus determining the functionality of the RFID transponder 120 and the tested chip 130. The RFID reader 110 sends the command signal 111 for the self-destruction of the RFID transponder based on the response signal 121. The RFID transponder 120 receives the command signal 111 and initiates self-destruction based on the command signal 111. The RFID transponder can also compare the command signal 111 with a lookup table (not shown) to determine whether to send the response signal 121 or initiate self-destruction. For example, the command signal 111 and the lookup table (not shown) can both consist of two digits. The two digits representing the self-destruction of the RFID transponder can be "00", and the two digits of the command signal 111 representing the response or functionality of the RFID transponder can be "11". Furthermore, the RFID reader 110 determines that the tested chip 130 has no edge cracks when the response signal 121 is received, indicating the functionality of the RFID transponder 120. After the RFID transponder 120 self-destructs, it no longer outputs a response signal 121 and has no effect on the tested chip 130. Additionally, the RFID reader 110 outputs the command signal 111 in the form of an electromagnetic wave, and the RFID transponder 120 also outputs the response signal 121 in the form of an electromagnetic wave. Fig. 2 is a flowchart for a method for detecting edge cracks in a tested chip according to some embodiments. As shown in Fig. 1 and Fig. 2, a method 200 is provided. The method 200 comprises the following operations: receiving a command signal 111 (202); supplying energy from the command signal 111 (204); supplying a response signal 121 based on the command signal 111 (206); and performing self-destruction based on the command signal 111 (208). The method 200 further comprises comparing the command signal 111 with a lookup table (not shown) to determine whether to output the response signal 121 or to initiate self-destruction. Fig. 3 is a flowchart for a method for detecting edge cracks in a tested chip according to some embodiments. As shown in Fig. 1 and Fig. 3, a method 300 is provided. The method 300 comprises the following operations: by means of an RFID reader 110, providing a command signal 111 for a response from an RFID transponder (302); by means of an RFID transponder 120, receiving the command signal 111 and generating energy from the command signal 111 (304); by means of an RFID transponder 120, providing a response signal 121 based on the command signal 111 (306); by means of an RFID reader 110, receiving the response signal 121 and providing the command signal 111 for the self-destruction of the RFID transponder based on the response signal 121 (308); and by means of an RFID transponder 120, receiving the command signal 111 and initiating the self-destruction based on the command signal 111 (310). Furthermore, the method 300 may include: arranging a processor 124 of the RFID transponder 120 under a sealing ring 131 of the chip 130. The method 300 may also include: arranging an antenna 122 of the RFID transponder 120 outside a sealing ring 131 of the chip 130. The method 300 may also include: determining that the chip 130 has no edge cracks when receiving the response signal 121. The method 300 may also include: ceasing to provide the response signal 121 after the RFID transponder 120 has self-destructed. The method 300 may also include: exerting no effect on the chip 130 after the RFID transponder 120 has self-destructed.Procedure 300 may further include: using an RFID transponder 120, comparing the command signal 111 with a lookup table to determine whether to provide the response signal 121 or initiate self-destruction. Operation 302 may further include: providing the command signal 111 in the form of an electromagnetic wave. Operation 302 may further include: providing the response signal 121 in the form of an electromagnetic wave. Next, further details of the exemplary edge crack detection system are presented. Fig. 4 is a block diagram illustrating a wafer containing chips that have the exemplary RFID transponder, according to some embodiments. As shown in Fig. 4, a wafer 400 is provided. The wafer 400 has several chips separated by several scribing lines. For example, the first chip 402 and the second chip 404 are separated by scribing line 410. The first chip 402 comprises an RFID transponder 420 and a test chip 430. The RFID transponder 420 is physically connected to the test chip 430. The RFID transponder 420 is not limited to the shape shown in Fig. 4 and may include an antenna (not shown) surrounding the test chip 430. The antenna may have a width of 1 micrometer. The RFID transponder 420 may further include a processor located beneath a sealing ring of the test chip 430. The processor may have a width of 10 micrometers and a length of 500 micrometers. The second chip 404 comprises another RFID transponder 440 and another tested chip 450. The function of the RFID transponder 440 and the tested chip 450 is similar to that of the RFID transponder 420 and the tested chip 430 and will not be repeated here. The wafer 400 is cut along these scribing lines to produce individual chips. For example, the wafer 400 is cut along scribing line 410 to produce the first chip 402 and the second chip 404. In this embodiment, the cutting is carried out using techniques such as physical sawing or laser sawing. Fig. 5 is a block diagram illustrating the exemplary edge-tear detection system using tape-and-reel packaging according to some embodiments. As shown in Fig. 5, the chips are placed on the tape-and-reel device 508 for shipment to the customer. However, tears easily occur during tape-and-reel packaging, damaging the chips. Using an exemplary edge-tear detection system 510, comprising an RFID reader 502 and an RFID transponder 420 wirelessly connected to the RFID reader 502, the chips with tears can be easily detected. In this embodiment, a crack 506 develops in the first chip 402 during tape-and-reel packaging, damaging the RFID transponder 420 and the chip 430 under test. When the tape-and-reel packaging tool 504 requests the RFID reader 502 to issue a command signal 503, the RFID transponder 420 is unable to receive the command signal 503 and send a response signal. Consequently, the tape-and-reel packaging tool 504, which is connected to the RFID reader 502, cannot receive a response signal. Therefore, the tape-and-reel packaging tool 504 detects a failure of the first chip 402. In this embodiment, the second chip 404 does not develop a crack. If the tested chip 450 has no edge cracks, the RFID transponder 440, which is connected to the chip 450, is functional and can send a response signal to the RFID reader 502. That is, when the response signal is received, the RFID reader 502 determines that the tested chip 450 has no edge cracks. Furthermore, after determining that the chip 450 has no edge cracks, the RFID reader 502 sends a self-destruct command to destroy or deactivate the RFID transponder 440, so that the method has no effect on the normal function of the chip 450. Fig. 6 is a block diagram illustrating an exemplary RFID transponder according to some embodiments. The RFID transponder 120 can be configured as shown in Fig. 6. The RFID transponder 120 comprises an antenna 602, an analog front end (AFE) 610, a microcontroller (MCU), and a memory 630. The analog front end (AFE) 610 comprises an envelope detector 611, a rectifier 612, a voltage regulator 613, a reset unit 614, and a modulator 615. The RFID transponder 120 is connected to a tested chip. Antenna 602 receives the command signal 603. Rectifier 612 and voltage regulator 613 generate power 618 from the command signal 603. Reset unit 614 sends a reset signal 619 to initialize MCU 620. Envelope detector 611 extracts a demodulated signal 616 and a clock 617 from the command signal 603. MCU 620 outputs a control signal 621 to modulator 615 based on the demodulated signal 616. Via antenna 602, modulator 615 modulates the control signal 621 and sends the response signal 121 to an RFID reader (not shown). The response signal 121 can carry information about the functionality of the RFID transponder 120 and the chip under test. After the functionality has been confirmed, the MCU 620 further performs a self-destruction based on the demodulated signal 616 and the data in memory 630. According to an exemplary embodiment, a method for detecting edge cracks in a chip under test is provided. The method comprises the following operations: receiving a command signal; supplying energy from the command signal; supplying a response signal based on the command signal; and performing self-destruction based on the command signal. According to an exemplary embodiment, a method for detecting edge cracks in a tested chip is provided. The method comprises the following operations: providing a command signal for a response from an RFID transponder using an RFID reader; receiving the command signal and generating energy from it using an RFID transponder; providing a response signal based on the command signal using an RFID transponder; receiving the response signal and providing the command signal for the self-destruction of the RFID transponder based on the response signal using an RFID reader; and receiving the command signal and initiating self-destruction based on the command signal using an RFID transponder. According to an exemplary embodiment, an edge crack detection system is provided for a tested chip. The system comprises an RFID reader and an RFID transponder. The RFID reader outputs a command signal. The RFID transponder is wirelessly connected to the RFID reader, receives the command signal, generates energy from the command signal, and outputs a response signal based on the command signal. The RFID reader receives the response signal and provides the command signal for the self-destruction of the RFID transponder based on the response signal, and the RFID transponder receives the command signal and initiates self-destruction based on the command signal.

Claims

A method for detecting edge cracks in a tested chip (130), comprising: receiving a command signal (111) by means of an antenna (122) of an RFID transponder (120), wherein the antenna (122) surrounds the chip (130); supplying energy from the command signal (111); supplying a response signal (121) based on the command signal (111) by means of the antenna (122) of the RFID transponder (120); and performing a self-destruction of the RFID transponder (120) based on the command signal (111). The method of claim 1, further comprising comparing the command signal (111) with a lookup table to determine whether to provide the response signal (121) or to initiate self-destruction. A method for detecting edge cracks in a tested chip (130), comprising: providing a command signal (111) for a response from an RFID transponder (120) by means of an RFID reader (110); receiving the command signal (111) for a response from the RFID transponder (120) by means of an antenna (122) of the RFID transponder (120), wherein the antenna (122) surrounds the chip (130); generating energy from the command signal (111) by means of the RFID transponder (120); providing a response signal (121) based on the command signal (111) by means of the antenna (122) of the RFID transponder (120); and receiving the response signal (121) and providing a command signal by means of the RFID reader (110). (111) for self-destruction of the RFID transponder (120) based on the response signal (121); by means of the antenna (122) of the RFID transponder (120), receiving the command signal (111) for the self-destruction of the RFID transponder (120);and by means of the RFID transponder (120), initiating self-destruction based on the command signal (111).; Method according to claim 3, which further comprises arranging a processor (124) of the RFID transponder (120) under a sealing ring (131) of the chip (130). Method according to claim 3 or 4, which further comprises arranging an antenna (122) of the RFID transponder (120) outside a sealing ring (131) of the chip (130). Method according to any one of claims 3 to 5, further comprising determining that the tested chip (130) has no edge cracks when the response signal (121) is received. Method according to any one of claims 3 to 6, which further comprises terminating the provision of the response signal (121) after the self-destruction of the RFID transponder (120). Method according to one of claims 3 to 7, wherein after the self-destruction of the RFID transponder (120) there are no effects on the tested chip (130). A method according to any one of claims 3 to 8, further comprising comparing the command signal with a lookup table using an RFID transponder (120) to determine whether the response signal (121) should be provided or self-destruction should be initiated. Method according to any one of claims 3 to 9, wherein providing the command signal (111) by means of an RFID reader (110) further comprises providing the command signal (111) in the form of an electromagnetic wave. Method according to any one of claims 3 to 10, wherein providing the response signal (121) by means of an RFID transponder (120) further comprises providing the response signal (121) in the form of an electromagnetic wave. Edge crack detection system (100) for a tested chip (130) comprising: an RFID reader (110) configured to provide a command signal (111);and an RFID transponder (120) wirelessly connected to the RFID reader (110) and comprising an antenna (122) surrounding the chip (130), wherein the RFID transponder (120) is configured to receive the command signal (111) via the antenna (122), to generate energy from the command signal (111) and to provide a response signal (121) based on the command signal (111) via the antenna (122), wherein the RFID reader (110) is configured to receive the response signal (121) and to provide a command signal (111) for self-destruction of the RFID transponder (120) based on the response signal (121), and wherein the RFID transponder (120) is configured to provide the command signal (111) for self-destruction of the to receive RFID transponders (120) via the antenna (122) and to initiate self-destruction based on the command signal (111). System (100) according to claim 12, wherein the RFID reader (110) determines that the tested chip (130) has no edge cracks when the response signal (121) is received. System (100) according to claim 12 or 13, wherein after the self-destruction of the RFID transponder (120) the RFID transponder (120) no longer provides a response signal (121). System (100) according to one of claims 12 to 14, wherein after the self-destruction of the RFID transponder (120) the RFID transponder (120) has no effect on the tested chip (130). System (100) according to one of claims 12 to 15, wherein the RFID transponder (120) compares the command signal (111) with a lookup table to determine whether to provide the response signal (121) or to initiate self-destruction. System (100) according to one of claims 12 to 16, wherein the RFID reader (110) provides the command signal (111) in the form of an electromagnetic wave. System (100) according to one of claims 12 to 17, wherein the RFID transponder (120) provides the response signal (121) in the form of an electromagnetic wave. System (100) according to one of claims 12 to 18, wherein the RFID transponder (120) further comprises a processor (124) arranged under a sealing ring (131) of the chip (130). System (100) according to one of claims 12 to 19, wherein the RFID transponder (120) further comprises an antenna (122) outside a sealing ring (131) of the chip (130).

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