Method of detecting cracks in semiconductor elements and related

Abstract

A wire bonding system includes: a horn assembly configured to carry a wire bonding tool for performing a wire bonding operation with respect to a workpiece containing a semiconductor element; the supporting structure is used for supporting the workpiece; and a computer system configured to: provide the semiconductor element on the wire bonding system; and detecting whether there is a crack in the semiconductor element on the wire bonding system.

Description

Cross-reference to related applications

[0001] This application claims priority to U.S. Provisional Application No. 63 / 526,054, filed July 11, 2023, the contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to a method for detecting cracks / fractures in semiconductor devices and related wire bonding systems. Background Technology

[0003] In the electronics assembly industry, wire bonding / lead bonding remains a primary method for providing electrical interconnections between two (or more) locations within a workpiece. In conventional wire bonding applications, bonding tools (e.g., capillary bonding / lead bonding tools in ball bonding applications, wedge bonding tools in wedge bonding applications, etc.) are used to bond a first end of a lead to a first bonding location to form a first bond. Then, a continuous section of lead, along with the first bond, extends toward a second bonding location. Subsequently, a second bond (continuous with the first bond and the lead section) is formed at the second bonding location. Thus, a wire arc / lead loop is formed between the first and second bonding locations. During the formation of the wire bond, various forms of energy (e.g., ultrasound, thermosonics, thermocompression, etc.) can be used regarding the bonding force and / or heat.

[0004] The formation of cracks in semiconductor components (e.g., semiconductor dies) is a concern in the electronics assembly industry. Such crack formation is often a worrying concern in processes involving overhanging dies (e.g., the unsupported portion of a semiconductor die in a semiconductor device). However, cracking can occur in any type of semiconductor package or device.

[0005] U.S. Patent Nos. 10,121,759 and 10,665,564 (both titled "ON-BONDERAUTOMATIC OVERHANG DIE OPTIMIZATION TOOL FOR WIRE BONDING AND RELATEDMETHODS") relate to techniques for optimizing wire bonding operations for unsupported portions of semiconductor devices (e.g., overhanging bare dies).

[0006] Unfortunately, the presence and / or formation of cracks in semiconductor devices often remain undetected until time and / or effort have been consumed in the processes associated with the semiconductor device (e.g., performing wire bonding operations associated with the semiconductor device). Therefore, improvements in crack detection for semiconductor devices are needed. Summary of the Invention

[0007] According to an exemplary embodiment of the present invention, a method for detecting cracks in a semiconductor element on a wire bonding system is provided. The method includes the following steps: (a) providing the semiconductor element on the wire bonding system; and (b) detecting whether there are cracks in the semiconductor element on the wire bonding system.

[0008] According to other embodiments of the present invention, the method described in the preceding paragraph may have any one or more of the following features: step (b) includes determining the z-axis position of a portion of the semiconductor element to detect whether there is a crack in the semiconductor element; step (b) includes performing an imaging operation on the wire bonding system to detect whether there is a crack in the semiconductor element; step (b) includes determining the z-axis position of a skewed portion of the semiconductor element to detect whether there is a crack in the semiconductor element; step (b) includes determining the z-axis position of a portion of the semiconductor element during a wire bonding operation to detect whether there is a crack in the semiconductor element; step (b) includes performing an imaging operation on the wire bonding system to detect whether there is a crack in the semiconductor element; the imaging operation includes (i) on the semiconductor... (ii) Before the wire bonding portion on the body element is formed and after the wire bonding portion on the semiconductor element is formed, a portion of the semiconductor element is imaged; step (b) includes monitoring electrical characteristics related to the ultrasonic energy applied during the wire bonding operation to detect whether there is a crack in the semiconductor element; the electrical characteristics are impedance values ​​related to the operation of the ultrasonic transducer; step (b) includes using a first bonding head assembly of the wire bonding system to detect whether there is a crack in the semiconductor element, the method further including step (c): bonding a wire to the semiconductor element using a second bonding head assembly of the wire bonding system; and / or step (b) includes contacting a deflected portion of the semiconductor element with a contact tool carried by the first bonding head assembly to detect whether there is a crack in the semiconductor element.

[0009] According to another exemplary embodiment of the present invention, a wire bonding system is provided. The wire bonding system includes a bonding head assembly configured to carry a wire bonding tool for performing wire bonding operations relative to a workpiece including a semiconductor element. The wire bonding system also includes a support structure for supporting the workpiece. The wire bonding system further includes a computer system configured to detect whether there are cracks in the semiconductor element on the wire bonding system.

[0010] According to other embodiments of the present invention, the wire bonding system described in the preceding paragraph may have any one or more of the following features: another bonding head assembly, wherein the other bonding head assembly is configured to carry a contact tool used in conjunction with detecting whether there is a crack in the semiconductor element; another bonding head assembly, wherein the other bonding head assembly is configured to carry an imaging system used in conjunction with detecting whether there is a crack in the semiconductor element; the computer system is configured to determine the z-axis position of a portion of the semiconductor element to detect whether there is a crack in the semiconductor element; and the imaging system attached to the bonding head assembly, wherein the imaging system is configured to perform an imaging operation on the wire bonding system to detect The semiconductor element is free from cracks; the imaging system is configured to (i) image a portion of the semiconductor element before and (ii) after the wire bonding portion on the semiconductor element is formed; the computer system is configured to determine the z-axis position of a skewed portion of the semiconductor element to detect whether there is a crack in the semiconductor element; the computer system is configured to determine the z-axis position of a portion of the semiconductor element during wire bonding operations to detect whether there is a crack in the semiconductor element; the computer system is configured to monitor electrical characteristics related to the ultrasonic energy applied during wire bonding operations; and / or the electrical characteristics are impedance values ​​related to the operation of the ultrasonic transducer. Attached Figure Description

[0011] The invention is best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be emphasized that, by convention, the various features in the drawings are not drawn to scale. Instead, for clarity, the dimensions of the various features have been arbitrarily enlarged or reduced. The drawings include the following figures: Figures 1A to 1C This is a block diagram side view of a portion of a wire bonding system according to an exemplary embodiment of the present invention; Figure 2 It is a timing diagram illustrating the z-axis profile of a portion of the bonding head assembly of the bonding system during the formation of the lead bonding section, applicable to various exemplary embodiments of the present invention; Figures 3A to 3B These are schematic diagrams illustrating the effect of solder force on the die skew of an unbroken semiconductor element and the effect of solder force on the die skew of a broken semiconductor element, applicable to various exemplary embodiments of the present invention; Figures 4A to 4D and Figures 5A to 5D These are block diagram side and top views of various parts of another wire bonding system according to an exemplary embodiment of the present invention; Figures 6A to 6B It is a timing diagram illustrating the electrical characteristics of the ultrasonic energy applied during wire bonding operations, applicable to various exemplary embodiments of the present invention; Figure 7 This is a block diagram side view of a portion of yet another wire bonding system according to an exemplary embodiment of the present invention; and Figure 8 This is a flowchart illustrating a method for detecting cracks in semiconductor devices on a wire bonding system according to various exemplary embodiments of the present invention. Detailed Implementation

[0012] As used herein, the term "semiconductor element" means any structure that includes (or is configured to include in subsequent steps) a semiconductor chip or bare die. Exemplary semiconductor elements include, in particular, substrates (e.g., leadframes, PCBs, carriers, etc.), substrates carrying one or more semiconductor bare dies, exposed semiconductor bare dies, packaged semiconductor devices, flip-chip semiconductor devices, bare dies embedded in a substrate, and stacks of semiconductor bare dies. Furthermore, a semiconductor element may include elements configured to be soldered or otherwise included in a semiconductor package (e.g., spacers, substrates, etc., to be soldered in a stacked bare die configuration).

[0013] As used herein, the term "crack" can refer to any unwanted unevenness in the configuration of a semiconductor element (e.g., a semiconductor die) being wire-bonded. For example, a crack can refer to permanent or plastic deformation in a semiconductor die, such as die splitting (partially or completely) or a depression formed in the die. In another example, a crack can be a fracture and / or void in a semiconductor die. In yet another example, a crack can be a missing portion of a semiconductor die.

[0014] As used in this article, the term "electric characteristic" can mean impedance, voltage, current, power draw, and the like.

[0015] According to specific exemplary embodiments of the present invention, methods and systems are provided for detecting cracks in semiconductor elements (e.g., bare semiconductor dies) on a bonding system. Specific exemplary methods for detecting such cracks on wire bonders can be performed instantaneously.

[0016] In a particular exemplary embodiment of the invention, a method for detecting the presence of a crack in a semiconductor element includes measuring the deflection of a portion of the semiconductor element during force application (e.g., a z-axis encoder in a wire bonding system). In other exemplary embodiments of the invention, a method for detecting the presence of a crack in a semiconductor element includes monitoring electrical characteristics with respect to ultrasonic energy applied during wire bonding operations (e.g., impedance monitoring). In other exemplary embodiments of the invention, a method for detecting the presence of a crack in a semiconductor element employs an imaging system (e.g., imaging a portion of the semiconductor element before and / or after the formation of a wire bond on a portion of the semiconductor element). These and other methods within the scope of the invention may be combined as needed (e.g., a combination of deflection measurement and imaging system detection; a combination of deflection measurement and monitoring of electrical characteristics; a combination of monitoring of electrical characteristics and imaging system detection, etc.).

[0017] The specific methods and systems described herein allow for the inspection of semiconductor devices (e.g., bare semiconductor dies) prior to wire bonding formation. Such inspection can target cracks (e.g., "die cracks") caused by processes occurring prior to wire bonding (e.g., wafer backside grinding, dicing, die bonding, probing, etc.). Furthermore, aspects of the invention also relate to crack inspection after wire bonding operations (e.g., after wire bonding has been formed).

[0018] Specific embodiments of the present invention utilize wire bonding systems (e.g., wire bonding machines, wire bonders, etc.) to detect cracks in real time. Specific embodiments use wire bonding systems (e.g., wire bonding machines, wire bonders, etc.) to mechanically test semiconductor devices for cracks before and / or after wire bonding. As described herein, in specific embodiments, ultrasonic-based crack detection (e.g., monitoring electrical properties with respect to ultrasonic energy applied during wire bonding operations) and image-based crack detection (e.g., image-based, optical, etc.) (e.g., detecting cracks as if seen from a top view of the semiconductor device) can be used. In specific embodiments, infrared cameras, laser systems, and ultrasonic-based non-destructive sensing systems can be used (e.g., as alternatives to or additional means to mechanical detection mechanisms) for crack detection on wire bonding systems.

[0019] When a wire bonding tool (e.g., carried by the bonding head assembly of a wire bonder) contacts a bonding pad (or other bonding location) on an unsupported portion of an overhanging die (or another overhanging portion of a semiconductor device), the die surface can be tilted downwards. For example, such tilting can cause several problems related to lead bonding and / or loop formation due to die vibration as the wire bonding tool rises away from the die surface after bonding. When a “crack” exists in the overhanging die, such a defect can damage the entire semiconductor package or workpiece (e.g., through excessive tilting, die breakage, etc.).

[0020] Specific aspects of this invention relate to the automated execution of in-situ crack detection, pre-weld crack detection, and / or post-weld crack detection. According to a specific exemplary embodiment of the invention, the welding procedure is taught by programmed welding positions (e.g., positions on an overhanging bare die). A welding tool (e.g., a capillary) makes downward contact at each programmed welding position (e.g., with or without leads joined in the welding tool) using predetermined starting values ​​of specific parameters (such as damping gain, constant speed) (e.g., in constant speed mode) and a welding force. A z-axis encoder is used to provide data (e.g., position values ​​along the vertical "z-axis"), which is then collected and analyzed. This data can be compared with user-defined values ​​(e.g., permissible die skew, desired welding force, etc.) to determine the presence of cracks.

[0021] Sometimes, die cracks can manifest as microcracks, which are not obvious during the manufacturing process and are difficult to detect. Typically, such microcracks remain undetectable until subsequent functional testing is performed. In certain cases, semiconductor devices fail during final functional testing of the packaged or end product (e.g., after capsule packaging). Currently, functional testing is performed "offline" and in cumbersome procedures. When microcracks go undetected and failure occurs during functional device testing, the entire production batch may be returned. The specific embodiments described herein have the capability to detect cracks at an earlier stage, preventing future failures. The ability to detect cracks in situ and / or on-the-spot using wire bonding systems (e.g., wire bonding machines) saves time and materials and significantly increases throughput. The methods and systems described herein improve or optimize processes that minimize or eliminate crack-related problems.

[0022] Throughout the accompanying drawings, the same reference numerals refer to the same elements. Therefore, the description of specific elements relating to a particular drawing may apply throughout the drawings unless otherwise indicated in the context.

[0023] Please refer to the attached diagram now. Figures 1A to 1CThe diagram illustrates a wire bonding system 100. The wire bonding system 100 includes a bonding head assembly 116 for bonding one or more leads to a semiconductor element 104 (e.g., a bare die in a workpiece 126). The bonding head assembly 116 is configured to carry wire bonding tools (e.g., capillaries, wedge bonding tools, etc.) for performing wire bonding operations relative to the workpiece 126 having the semiconductor element 104. The bonding head assembly 116 includes a z-axis encoder 116c to measure the z-axis position (e.g., vertical position) of the bonding head assembly 116 of the wire bonding system 100. As those skilled in the art will understand, the bonding head assembly 116 may include multiple elements configured to travel along multiple axes of the wire bonding system 100 (e.g., along the x-axis, along the y-axis, along the z-axis, etc.). These elements may include, for example, ultrasonic transducers, imaging systems, lead clamps, and various other elements. The z-axis encoder 116c may be positioned on the bonding head assembly 116 as needed.

[0024] The wire bonding system 100 also includes a support structure 124 for supporting a workpiece 126 (including a semiconductor element 104). The wire bonding system 100 also includes a computer system 118. The computer system 118 can be configured to control the movement of the bonding head assembly 116. The computer system 118 can also be configured to detect the presence of cracks in the semiconductor element 104 (e.g., and / or semiconductor element 114…etc.) on the wire bonding system 100. In a particular embodiment, the computer system 118 can be configured to determine the z-axis position of a portion of the semiconductor element (e.g., a skewed portion) to detect the presence of cracks in the semiconductor element. In a particular embodiment, the computer system 118 can be configured to communicate with an imaging system (e.g., an imaging system carried by the bonding head assembly 116) to detect the presence of cracks in the semiconductor element. In a particular embodiment, the computer system 118 can be configured to monitor electrical characteristics (e.g., impedance values) related to the ultrasonic energy applied during the wire bonding operation.

[0025] Therefore, at least in association with computer system 118, wire bonding system 100 can be configured to detect whether there are cracks in semiconductor elements 104 (e.g., and / or semiconductor elements 114…etc.) on wire bonding system 100. As those skilled in the art will understand, computer system 118 can be any type of computing device (e.g., controller, computer included as part of wire bonding system 100, computer system remote from wire bonding system 100, multiple computing devices such as processor for wire bonding system 100…etc.).

[0026] exist Figures 1A to 1CIn this illustration, workpiece 126 is depicted disposed on support structure 124. Workpiece 126 is an exemplary workpiece; however, it is understood that the invention is not limited to any specific workpiece. The invention has broad applicability and covers a wide variety of workpiece styles. The illustrated workpiece 126 includes a substrate 106 disposed directly on support structure 124. Semiconductor element 114 (e.g., "bottom die") is depicted disposed on substrate 106 using adhesive 112 (e.g., die bonding adhesive). Spacer 110 is depicted disposed on semiconductor element 114 using adhesive 112. Semiconductor element 104 (e.g., "top die") is depicted disposed on spacer 110 using adhesive 112.

[0027] For details, please refer to the following: Figure 1A The free air ball 108a (FAB) is illustrated as the end of a bonding tool 102 (e.g., a capillary) provided at a height H1 (e.g., relative to a reference line on the wire bonding system 100) prior to the wire bonding operation. The free air ball 108a is formed from a lead 108 (wherein the lead 108 is configured to pass through the bonding tool 102). The free air ball 108a contacts a portion (e.g., the top surface) of a semiconductor element 104 (wherein the top surface of the semiconductor element 104 is shown at a height H2, another height relative to the reference line). The semiconductor element 104 is illustrated in an "overhang" state, where the unsupported portion 104a of the semiconductor element 104 is not directly supported from below. A wire arc 108b is illustrated below the semiconductor element 104.

[0028] Now for reference Figure 1B The wire bonding tool 102 is depicted as having moved downwards (i.e., along the vertical z-axis direction) by applying a predetermined force for the wire bonding operation (e.g., arc forming operation). Figure 1B For the sake of brevity, certain structures of the wire bonding system 100 (e.g., solder head assembly 116, support structure 124, computer system 118, etc.) are omitted. The airless solder ball 108a is depicted in a deformed state as the first bond portion 108c (or, in a particular application, an extruded body). The end of the wire bonding tool 102, which has moved downward, is now at height H3, which is lower than height H1 (i.e., closer to the substrate 106). With the end of the wire bonding tool 102 at height H3, the top surface of the semiconductor element 104 is now at height H4, which is lower than height H2 (i.e., closer to the substrate 106). In other words, as a result of the force applied for the wire bonding operation, the unsupported portion 104a of the semiconductor element 104 is depicted in a deformed, altered, or bent state.

[0029] Now for reference Figure 1C The wire bonding tool 102 is depicted as having moved downwards (i.e., along the vertical z-axis). The unsupported portion 104a is depicted as broken, forming an unsupported portion 104a′ and a fragmented portion 104a″. It should be understood that this depiction is not to scale. The fragmented portion 104a″ may not be completely separated from the rest of the semiconductor element 104. The end of the downward-moving wire bonding tool 102 is now at height H5, which is lower than heights H1 and H3 (i.e., closer to the substrate 106). With the end of the wire bonding tool 102 at height H5, the top surface of the semiconductor element 104 is now at height H6, which is lower than heights H2 and H4 (i.e., closer to the substrate 106). Thresholds for the height of the wire bonding tool 102 and / or the height of the top surface of the semiconductor element 104 can be used to determine whether a crack exists in the semiconductor element 104. For example, it is inferred that any height of the wire bonding tool 102 below height H3 indicates the presence of a crack in the semiconductor element 104. Since height H5 is lower than height H3, the wire bonding tool 102 reaching height H5 can be used to detect cracks in the semiconductor element 104. For example, it is inferred that any height of the top surface of the semiconductor element 104 below height H4 indicates the presence of a crack in the semiconductor element 104. Since height H6 is lower than height H4, the top surface of the semiconductor element 104 reaching height H6 can be used to detect cracks in the semiconductor element 104. Of course, these are merely examples of how the skewness of the unsupported portion of the semiconductor element 104 can be used to detect cracks in the semiconductor element 104.

[0030] Furthermore, when Figures 1A to 1C When illustrating height values ​​relative to specific locations (e.g., the end of the soldering tool 102, the top surface of the semiconductor element 104, etc.), it should be understood that these are simple examples of height values ​​that can be monitored for crack detection. According to the invention, any suitable height value can be monitored for crack detection.

[0031] Now for reference Figure 2 The diagram illustrates the vertical position of the wire bonding tool 102 during a crack detection operation (in this case, occurring simultaneously with the wire bonding operation). As shown, the z-axis profile of the wire bonding tool 102 when a crack is present (e.g., from before the bonding operation, caused by the bonding operation; ... etc.) differs from the z-axis profile when there is no crack (i.e., in the "normal" case). For example, compared to the minimum value M in the "normal" case... n The minimum value M in the presence of cracks c They have identifiable differences.

[0032] In addition to measuring height values ​​(e.g., Figure 1C (H5 and / or H6) and threshold (e.g., Figure 1B Beyond the comparison of H3 and / or H4, cracks may be detected as a function of the vertical position profile changing over time. For example, a crack can be detected if a semiconductor element is bent or buckled at a rate higher than expected (e.g., but before reaching a “threshold” value). For example, regarding Figure 2 When a wire bonding tool deforms a semiconductor element, the slope of the profile can be compared with a reference slope to determine whether a crack exists in the semiconductor element.

[0033] Now for reference Figures 3A to 3B The diagram illustrates the deflection of a semiconductor element (e.g., a bare semiconductor die) as a function of force in relation to a crack detection operation (which in this example occurs simultaneously with the wire bonding operation). See details. Figure 3A The illustration depicts an exemplary "normal" crack detection operation (and wire bonding operation). As shown, a semiconductor device (e.g., Figures 1A to 1B The skewness of the semiconductor element 104 exhibits a generally linear relationship, where the amount of skewness is proportional to the applied force (e.g., applied using a wire bonding tool). It should be understood that... Figure 3A The linear shape in the equation is an approximation. In a particular configuration or application, the relationship can be non-linear (e.g., exponential, logarithmic, polynomial, etc.). However, this relationship may be considered a baseline (or expected relationship) from which the presence of a crack can be determined (e.g., when a specific offset relative to the expected relationship appears).

[0034] For details, please refer to the following: Figure 3B The diagram illustrates the crack detection process (and its simultaneous occurrence with the wire bonding operation) when a crack is present. As shown, the relationship between the semiconductor element and the applied force (e.g., labeled "welding force") is linear and constant from the origin until the fracture point P is reached. C (For example, see) Figure 1C (There are cracks in it). In P C At this point, the semiconductor element breaks and / or buckles, and then the semiconductor deflects at a greater rate as a function of the increasing force. Therefore, the crack can be detected (e.g., using computer system 118).

[0035] The wire bonding system 100 can be configured to use a variety of different techniques to detect cracks. For example, in a particular embodiment, crack detection can be performed using a computer system 118 associated with the welding tool 102 carried by the welding head assembly 116 (see, for example, see...). Figures 1A to 1CIn certain embodiments, another contact element or device can be used for crack detection. In certain embodiments, an imaging system (e.g., a camera and an illumination assembly) can be used for crack detection. In certain embodiments, a combination of an imaging system, a welding tool, and / or a contact element can be used for crack detection.

[0036] Now for reference Figures 4A to 4D and Figures 5A to 5D The diagram depicts wire bonding system 100'. Regarding... Figures 1A to 1C The description of wire bonding system 100 applies to wire bonding system 100' unless otherwise indicated. Wire bonding system 100' is substantially the same as wire bonding system 100, except that wire bonding system 100' additionally includes imaging system 120. It should be understood that, for the sake of brevity, certain structures of wire bonding system 100' (e.g., bonding head assembly 116, support structure 124, computer system 118, etc.) have been omitted in certain figures.

[0037] Figures 4A to 4D and Figures 5A to 5D The diagram illustrates a non-overhang configuration of semiconductor devices 104 / 114 and substrate 106 (in contrast to...). Figures 1A to 1C (Application shown in Chinese). In Figures 4A to 4D and Figures 5A to 5D In the diagram, workpiece 128 is depicted on support structure 124 (not shown in the diagram). Figures 4B to 4D and Figures 5A to 5D Semiconductor element 114 (e.g., "bottom die") is illustrated as being disposed on substrate 106 using adhesive 112 (e.g., die attach adhesive). Semiconductor element 104 (e.g., "top die") is illustrated as being disposed on semiconductor element 114 using adhesive 112.

[0038] Figures 4A to 4D The illustration depicts the use of an imaging system 120 for applications where no cracks are detected. A solder head assembly (e.g., solder head assembly 116, other solder head assemblies, etc.) can be configured to carry the imaging system 120, which is used to detect the presence of cracks in a semiconductor element (e.g., semiconductor element 104). In a particular embodiment, the imaging system 120 is not carried by a solder head assembly (not shown), wherein the imaging system 120 is configured to perform imaging operations on a wire bonding system 100' for detecting the presence of cracks in the semiconductor element (e.g., semiconductor element 104). In a particular embodiment, the imaging system 120 is configured to image a portion of the semiconductor element (e.g., semiconductor element 104) before and after the formation of a solder joint on the semiconductor element.

[0039] Now for reference Figure 4AAirless solder ball 108a (i.e., FAB) is illustrated at the end of soldering tool 102 (e.g., capillary) prior to wire bonding operation. Figure 4A In this context, the imaging system 120 can optionally provide one or more images of the semiconductor element 104 (related to the computer system 118, not shown) prior to the wire bonding operation. These images can be used in conjunction with the wire bonding operation in relation to a crack detection procedure (e.g., see [reference]). Figure 4C Compare the images taken afterward (as described below). Figure 4B In this stage, the airless solder ball 108a is brought into contact with the top surface of the semiconductor element 104 prior to the wire bonding operation. During the wire bonding operation, an imaging system (involving digital processing hardware, such as...) is used... Figure 1A The computer system and related software displayed can provide real-time images for crack detection. Figure 4C In this stage, the first weld 108c (or extruded body) is depicted as formed (wherein, the entire arc, similar to...). Figure 4D The wire arc 108b can be formed using the first weld portion 108c. The welding head assembly (not shown) has been moved to the right (i.e., horizontal or in the +X direction), thereby moving the wire bonding tool 102 and the imaging system 120. Figure 4C The imaging system 120 provides a visualization of the image after the wire bonding operation, which is related to the computer system 118 (e.g., Figure 4D Image 122. (e.g.) Figure 4D The top view shown in image 122 does not depict any cracks. Therefore, the wire bonding system 100' can determine that cracks do not exist (and / or have not been detected). This determination can be performed automatically (e.g., using computer system 118). The captured image 122 can be recorded and displayed to the operator (e.g., machine operator, engineer, etc.). This crack detection procedure can be performed before the wire bonding operation (e.g., see...). Figure 4A (and the description above) and images taken after the wire bonding operation, or simply images taken after the wire bonding operation.

[0040] Figures 5A to 5D The illustration shows the use of imaging system 120 in an application where cracks have been detected. Now refer to... Figure 5A Airless solder balls 108a (i.e., FABs) are provided at the end of the bonding tool 102 (e.g., a capillary) prior to the wire bonding operation. Figure 5A In this context, imaging system 120 can optionally provide one or more images of semiconductor element 104 (as opposed to computer system 118, not shown) prior to wire bonding operations. These images can be used in conjunction with wire bonding operations related to crack detection procedures (e.g., see...). Figure 5C Compare the images taken afterward (as described below). Figure 5BDuring the wire bonding operation, the airless solder ball 108a is brought into contact with the top surface of the semiconductor element 104. During the wire bonding operation, an imaging system (involving digital processing hardware, such as...) is used... Figure 1A The computer system and related software displayed in the image can provide real-time images for crack detection. During the wire bonding operation, a crack appeared and was depicted as a fragmented section of 104″. Figure 5C In this stage, the first weld 108c (or extruded body) is depicted as formed (wherein, the entire arc, similar to...). Figure 5D The wire arc 108b can be formed using the first weld portion 108c. The welding head assembly (not shown) has been moved to the right (i.e., horizontal or in the +X direction), thereby moving the wire bonding tool 102 and the imaging system 120. Figure 5C The imaging system 120 provides a visualization of the image after the wire bonding operation, which is related to the computer system 118 (e.g., Figure 5D Image 122. (e.g.) Figure 5D The illustrated top view, image 122, clearly shows a crack. Therefore, the wire bonding system 100' can determine that a crack exists. This determination can be automated (e.g., using computer system 118). The captured image 122 can be recorded and displayed to an operator (e.g., machine operator, engineer, etc.). This crack detection procedure can be performed before the wire bonding operation (e.g., see...). Figure 5A (and the description above) and images taken after the wire bonding operation, or simply images taken after the wire bonding operation.

[0041] It should be understood that the imaging system 120 may have multiple embodiments. For example, the imaging system 120 may include an optical camera using visible light. In another example, the imaging system 120 may include an infrared camera. In another example, the imaging system 120 may include a laser system. In yet another example, the imaging system 120 may use electromagnetic radiation that can penetrate semiconductor elements (e.g., using X-rays and the like).

[0042] Now for reference Figures 6A to 6B The diagram shown is an exemplary schematic of electrical characteristics related to ultrasound-based detection. (Reference) Figure 6A The diagram illustrates ultrasonic current as a function of time. Ultrasonic current applied during "normal" operation (i.e., where the semiconductor element is not broken) (e.g., to the transducer of the welding head assembly) is assigned the reference letter I. An The ultrasonic current applied when a semiconductor element breaks (or has a crack) is assigned the reference letter I. Ac As shown in the figure, when a crack exists, the applied current I... Ac There were fluctuations during the wire bonding operation. In contrast, when there were no cracks, the applied current I... AnThe current remains relatively constant throughout the wire bonding operation. This current information can be used in crack detection procedures (e.g., using computer system 118).

[0043] refer to Figure 6B The diagram illustrates an exemplary representation of impedance as a function of time. The impedance during "normal" operation (i.e., where the semiconductor element is not broken), such as that of the transducer in the solder head assembly, is assigned the reference letter Z. An The impedance when a semiconductor element breaks (or has a crack) is assigned the reference letter Z. Ac As shown in the figure, when a crack is present (e.g., due to a discontinuity at the weld site), the impedance Z... Ac There were fluctuations during the wire bonding operation. In contrast, the applied current Z... An The bonding process is maintained at a relatively constant level throughout the entire wire bonding operation (as indicated by the Z symbol). An (The relatively flat portion of the drawing is marked). Such impedance information can be used in crack detection procedures (e.g., using computer system 118).

[0044] like Figures 6A to 6B As shown, ultrasonic current or impedance (or both) can be used to detect the presence of cracks (e.g., during wire bonding operations). It should be understood that other electrical properties (e.g., voltage) can be used for crack detection.

[0045] Now for reference Figure 7 The diagram illustrates a wire bonding system 200. The wire bonding system 200 includes a crack detection system 202 and a wire bonding system 206. The wire bonding system 200 also includes a support structure 210 for supporting workpieces (e.g., substrates, semiconductor devices, bare dies, etc.) and a material handling system 204. The crack detection system 202 includes a bonding head assembly 116a, which includes an imaging system 120. The bonding head assembly 116a is configured to carry the imaging system 120, which is used to detect whether there are cracks in the semiconductor device (e.g., similar to those found in...). Figures 4A to 4D and Figures 5A to 5D The techniques illustrated and described herein are used in connection with the present invention. The solder head assembly 116a is configured to support and / or carry a contact tool 208. The contact tool 208 may be a soldering tool (e.g., a capillary) or another tool (e.g., a non-soldering contact tool). The contact tool 208 can be used to detect the presence of cracks in a semiconductor device (e.g., similar to those found in...). Figures 1A to 1C The techniques illustrated and described herein are used in connection with the techniques described herein.

[0046] The wire bonding system 206 includes a bonding head assembly 116b, which is illustrated as a support for the bonding tool 102. The wire bonding system 206 is similar in many places to... Figures 1A to 1CThe wire bonding system 100. Accordingly, many descriptions of the wire bonding system 100 may be applied to the wire bonding system 206, unless otherwise indicated (or where different clarifications are made in the context). For example, the solder head assembly 116b is similar to the solder head assembly 116 (i.e., in... Figures 1A to 1C (in the middle).

[0047] Solder head assemblies 116a and 116b can be located in a common area or in separate areas (e.g., separate compartments), as illustrated by the vertical dashed lines. Material handling system 204 can move workpieces 126 / 128 (including semiconductor element 104) from crack detection system 202 to wire bonding system 206. In one example, after workpiece 126 / 128 has been indicated to have “passed” a crack detection test (e.g., using imaging system 120, contact tool 208, or one or more of the procedures described herein), workpiece 126 / 128 can be moved to wire bonding system 206 for wire bonding operations. Solder head assemblies 116a and 116b can be electronically or communicatively coupled to computer system 118. Therefore, computer system 118 can instruct solder head assembly 116b not to solder (e.g., semiconductor element 104 of workpiece 126 / 128) when a crack is detected.

[0048] It should be understood that, in Figure 7 Multiple embodiments of the system illustrated herein are conceivable. For example, multiple imaging systems 120 can be used (e.g., at least one imaging system 120 in the crack detection system 202 for pre-welding operations, and at least one imaging system 120 in the wire bonding system 206 for welding and post-welding operations).

[0049] Figure 8 This is a flowchart illustrating a method for detecting cracks in semiconductor devices on a wire bonding system. As will be understood by those skilled in the art, certain steps included in the flowchart may be omitted; certain additional steps may be added; and the order of steps may be changed from the order shown, all of which are included within the scope of this invention.

[0050] At step 800, a semiconductor element is provided to a wire bonding system (e.g., Figures 1A to 1C The wire bonding system 100). At step 802, a detection of whether there is a crack in the semiconductor element on the wire bonding system is performed. At optional step 802A (which may be part of step 802), the z-axis position of a portion (e.g., a skewed portion) of the semiconductor element (e.g., during the wire bonding operation) is determined to detect whether there is a crack in the semiconductor element (e.g., see...). Figures 1A to 1C , Figure 2 ,as well as Figures 3A to 3BAt optional step 802B (which may be part of step 802), an imaging operation is performed on the wire bonding system to detect whether there are cracks in the semiconductor element (e.g., see...). Figures 4A to 4D as well as Figures 5A to 5D In a particular embodiment, the imaging operation includes imaging a portion of the semiconductor element before and after the formation of a bond on the semiconductor element. At an optional step 802C (which may be part of step 802), an electrical characteristic related to the ultrasonic energy applied during the wire bonding operation is monitored to detect the presence of cracks in the semiconductor element (e.g., see...). Figures 6A to 6B In a particular embodiment, the electrical characteristic is an impedance value related to the operation of the ultrasonic transducer. It should be understood that in crack detection, any one of steps 802A, 802B, or 802C (separately or in combination) can be used. At step 804, the lead is soldered to the semiconductor element using the second solder head assembly of the wire bonding system (e.g., see...). Figure 4D and Figure 5D In the wire bonding system (108b), step 802 includes using a first bonding head assembly of the wire bonding system to detect whether there is a crack in the semiconductor element. In a particular embodiment, step 802 includes contacting a deflected portion of the semiconductor element with a contact tool carried by the first bonding head assembly to detect whether there is a crack in the semiconductor element.

[0051] Although the invention has been illustrated and described herein with reference to specific embodiments, it is not intended to limit the invention to the details shown. Rather, various modifications to the details may be made within the scope of the claims and their equivalents without departing from the invention.

Claims

1. A method of detecting a crack in a semiconductor element on a wire bonding system, the method comprising the steps of: (a) providing the semiconductor element on the wire bonding system; and (b) detecting whether there is a crack in the semiconductor element on the wire bonding system.

2. The method of claim 1, wherein, Step (b) includes determining a z-axis position of a portion of the semiconductor element to detect whether there is a crack in the semiconductor element.

3. The method of claim 2, wherein, Step (b) includes performing an imaging operation on the wire bonding system to detect whether there is a crack in the semiconductor element.

4. The method of claim 1, wherein, Step (b) includes determining a z-axis position of a deflected portion of the semiconductor element to detect whether there is a crack in the semiconductor element.

5. The method of claim 1, wherein, Step (b) includes determining a z-axis position of a portion of the semiconductor element during a wire bonding operation to detect whether there is a crack in the semiconductor element.

6. The method of claim 1, wherein, Step (b) includes performing an imaging operation on the wire bonding system to detect whether there is a crack in the semiconductor element.

7. The method of claim 6, wherein, The imaging operation includes (i) before a lead bond is formed on the semiconductor element and (ii) after the lead bond is formed on the semiconductor element, imaging a portion of the semiconductor element.

8. The method of claim 1, wherein, Step (b) includes monitoring an electrical characteristic related to ultrasonic energy applied during a wire bonding operation to detect whether there is a crack in the semiconductor element.

9. The method of claim 8, wherein, The electrical characteristic is an impedance value related to operation of an ultrasonic transducer.

10. The method of claim 1, wherein, Step (b) includes using a first bond head assembly of the wire bonding system to detect whether there is a crack in the semiconductor element, the method further comprising step (c): using a second bond head assembly of the wire bonding system to bond a lead to the semiconductor element.

11. The method of claim 10, wherein, Step (b) includes contacting a deflected portion of the semiconductor element with a contact tool carried by the first bond head assembly to detect whether there is a crack in the semiconductor element.

12. A wire bonding system comprising: a bond head assembly configured to carry a wire bonding tool for performing a wire bonding operation relative to a workpiece containing a semiconductor element; a support structure for supporting the workpiece; and a computer system configured to detect whether there is a crack in the semiconductor element on the wire bonding system.

13. The wire bonding system of claim 12, further comprising another bond head assembly, the other bond head assembly configured to carry a contact tool used in connection with detecting whether there is a crack in the semiconductor element. wherein 14. The wire bonding system of claim 12, further comprising another bond head assembly, the other bond head assembly configured to carry an imaging system used in connection with detecting whether there is a crack in the semiconductor element. wherein, the computer system configured to determine a z-axis position of a portion of the semiconductor element to detect whether there is a crack in the semiconductor element.

15. The wire bonding system of claim 12, wherein, the imaging system configured to perform an imaging operation on the wire bonding system to detect whether there is a crack in the semiconductor element.

16. The wire bonding system of claim 12, further comprising an imaging system attached to the bond head assembly, wherein, ​ 17. The wire bonding system of claim 16, wherein, The imaging system is configured to image a portion of the semiconductor element (i) prior to wire bond formation on the semiconductor element and (ii) after the wire bond formation on the semiconductor element.

18. The wire bonding system of claim 12, wherein, The computer system is configured to determine a z-axis position of a skewed portion of the semiconductor element to detect a crack in the semiconductor element.

19. The wire bonding system of claim 12, wherein, The computer system is configured to determine a z-axis position of a portion of the semiconductor element during a wire bonding operation to detect a crack in the semiconductor element.

20. The wire bonding system of claim 12, wherein, The computer system is configured to monitor an electrical characteristic related to ultrasonic energy applied during a wire bonding operation.

21. The wire bonding system of claim 20, wherein, The electrical characteristic is an impedance value related to operation of an ultrasonic transducer.

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