Semiconductor devices with a protective layer that facilitates the detection of microcracks

Abstract

The present invention provides a method for detecting microcracks within a semiconductor device before and / or after packaging the semiconductor device, and a semiconductor device assembly. [Solution] A protective layer 140 located on the active layer 130 of a semiconductor device 110' (e.g., its circuitry and the metal layer on the circuitry) is made of polyimide in which a fluorescent indicator 144 is dispersed throughout. The fluorescent indicator 144 contains microcapsules having a polymer shell 146' in the path of a microcrack 150, which ruptures when it intersects with the microcrack 150. When the polymer shell 146' ruptures, the fluorescent core 148' of the microcapsule is exposed and flows into the microcrack 150. The exposed fluorescent core 148' is excited by electromagnetic radiation of an appropriate wavelength or bandwidth (e.g., X-rays, etc.), and therefore any microcrack 150 within or adjacent to the protective layer 140 is visualized by radiographic imaging.

Description

Technical Field

[0001] Semiconductor devices are subject to stresses that can cause microcracks in them, especially during the assembly and packaging processes. Initially, the location and / or size of the microcracks may not affect the functionality of the semiconductor device, and the semiconductor device is typically tested before the semiconductor device is singulated from the wafer and after the semiconductor device is packaged. A semiconductor device that passes the electrical test but contains microcracks has a risk of future failure.

[0002] Therefore, it would be beneficial to enable the detection of microcracks in semiconductor devices before and / or after packaging the semiconductor devices.

Summary of the Invention

[0003] The semiconductor device assembly of the present disclosure includes a semiconductor substrate, at least one metal layer, and a polyimide layer in which visible microcrack indicators are dispersed.

[0004] The semiconductor substrate can carry a plurality of circuits that can be integrally formed within and on the semiconductor substrate. The plurality of circuits can define one or more semiconductor devices. The one or more semiconductor devices can include one or more memory devices such as NAND flash or NAND memory devices.

[0005] The semiconductor substrate can also be referred to as a semiconductive means. The semiconductor substrate can be a wafer (e.g., a silicon wafer, etc.) including a semiconductor material. Such a semiconductor substrate can carry a plurality of semiconductor devices, each of which includes a plurality of circuits. Alternatively, the semiconductor substrate can include a die cut from a wafer including a semiconductor material. Such a die can carry a single semiconductor device including a plurality of circuits.

[0006] At least one metal layer is sometimes referred to as a “redistribution means.” The at least one metal layer may include structures that facilitate communication between one or more semiconductor devices (or, more specifically, circuits of one or more semiconductor devices) supported by a semiconductor substrate and external electronic devices of the semiconductor devices. For example, the bond pads of each semiconductor device may be defined from at least one metal layer. In some examples, the at least one metal layer may include multiple layers defining bond pads, conductive traces, vias, etc. Such a metal layer may comprise a redistribution layer (RDL) of a semiconductor device assembly.

[0007] A polyimide layer may also be called a "protective layer" or "protective means." A polyimide layer can protect and / or insulate a metal layer. The polyimide layer is formed on the metal layer of a semiconductor device assembly. As its name suggests, the polyimide layer is formed from polyimide. In addition to conventional components of polyimide (e.g., polyamic acid, cyclohexane, curing agents, fillers, plasticizers, and surfactants), a fluorescent indicator may be dispersed throughout the polyimide layer.

[0008] The fluorescent indicator may also be referred to as the "fluorescent means." The fluorescent indicator may constitute up to about 1% of the weight of the polyimide. In some examples, the fluorescent indicator may comprise multiple microcapsules. Each microcapsule may comprise a fluorescent core and a shell (e.g., a polymer shell, a colloidal shell, etc.). Each microcapsule may have a diameter of about 1 μm to about 3 μm, but is not limited to these. The fluorescent core may contain a fluorescent dye. The shell, sometimes called the "encapsulating means," contains the fluorescent core. In some examples, the fluorescent core can prevent electromagnetic radiation (e.g., X-ray radiation, etc.) from exciting the fluorescent core. If the shell ruptures or is destroyed, the fluorescent core may be exposed. In examples where the fluorescent core contains a fluorescent dye, the fluorescent dye may flow into spaces adjacent to the microcapsule, such as microcracks, which spread into the microcapsule and cause its shell to rupture.

[0009] A polyimide layer containing a fluorescent dye may be used to facilitate the detection of microcracks within semiconductor devices before separating individual semiconductor devices from a wafer, after separating individual semiconductor devices from a wafer, but before packaging individual semiconductor devices, and / or before assembling individual semiconductor devices with other components of an electronic device (e.g., a printed circuit board), and / or after the packaging and / or assembly process.

[0010] When a polyimide layer is applied to one or more semiconductor devices, any microcracks in the polyimide layer can be detected. Microcracks may originate in the polyimide layer, or elsewhere in the semiconductor device, such as in the semiconductor substrate, one or more circuits of the semiconductor device, or a metal layer, and then propagate through the semiconductor device to the polyimide layer.

[0011] As microcracks form in and / or propagate through the polyimide layer, they can disrupt the fluorescent indicator in the polyimide layer, effectively activating it. Microcracks extending to the top of the active layer of a semiconductor device (e.g., a metal layer) can also activate the fluorescent indicator in the protective layer.

[0012] In examples where the fluorescent indicator includes microcapsules having a shell containing a fluorescent core, cracks in the polyimide layer may extend through the shell of at least one microcapsule, exposing the fluorescent core of each microcapsule within the path of the microcrack. The exposed fluorescent core can then flow into the microcrack.

[0013] A semiconductor device containing a polyimide layer with a fluorescent indicator can be inspected for the presence of microcracks in the polyimide layer. The semiconductor device can be inspected at various points in time before, during, and after its packaging. For example, the semiconductor device may be inspected before the semiconductor substrate (e.g., wafer) on which the semiconductor device was manufactured is diced or cut to separate the individual semiconductor devices from each other, i.e., before die fragmentation. Another example is that the semiconductor device can be inspected after separation from other semiconductor devices, or after dicing, or after die fragmentation. Yet another example is that the semiconductor device can be inspected before and after the packaging process (e.g., assembly, bonding, underfill, encapsulation, etc.). In some examples, after the polyimide layer is applied and before the manufacturer ships the device to the customer, the semiconductor device can be inspected for microcracks at several different points.

[0014] The inspection may include imaging of the semiconductor device. Imaging can be facilitated by radiation (e.g., X-ray radiation). When irradiated, any fluorescent indicators within or along microcracks can be excited so that the microcrack or a portion thereof can be visually distinguished from other locations on the semiconductor device. For example, a fluorescent indicator released by the rupture of a microcapsule shell by a microcrack and flowing into the microcrack can appear as a dark feature visually distinct from laterally adjacent features of the semiconductor device in a micrograph, or magnified image, or more simply, an image of the semiconductor device. Thus, a fluorescent indicator can make any microcrack in the polyimide layer visible to an individual viewing an image of the semiconductor device.

[0015] Other aspects of the disclosed subject matter, as well as the features and advantages of various aspects of the disclosed subject matter, should become apparent to those skilled in the art by considering the following description, the accompanying drawings, and the accompanying claims. [Brief explanation of the drawing]

[0016] Non-exclusive and non-exclusive examples are illustrated with reference to the following diagram. [Figure 1] This is a cross-sectional view of a semiconductor device, which includes a semiconductor substrate, a circuit supported by the semiconductor substrate, an active layer having a structure that facilitates communication between the circuit and an external electronic device, and a protective layer on the active layer. [Figure 2] Figure 1 is an X-ray microscope image of the type of semiconductor device shown, in which no microcracks are visible at all. [Figure 3] This shows a process for forming a protective layer on multiple semiconductor devices. [Figure 4] This is a cross-sectional view of an example of a semiconductor device having a semiconductor substrate, an active layer, and a protective layer on the active layer, the protective layer containing a fluorescent indicator. [Figure 5] Figure 4 is an orthogonal representation of an example of a semiconductor device. [Figure 6] An example of a fluorescent indicator that may be included in the protective layer of a semiconductor device is shown. [Figure 7] Figures 4 and 5 are orthogonal representations of examples of semiconductor devices, where microcracks extend through the protective layer and fluorescent indicators are located within the microcracks. [Figure 8] This is an example of an X-ray microscope image of a semiconductor device showing microscopic cracks. [Modes for carrying out the invention]

[0017] Figure 1 provides a cross-sectional view of a semiconductor device 10. The semiconductor device 10 includes a semiconductor substrate 20, an active layer 30 on the semiconductor substrate 20, and a protective layer 40 on the active layer 30. Without limitation, the semiconductor device 10 may comprise individual integrated circuits 12 separated from other integrated circuits 12, or, as shown in Figure 2, the semiconductor device 10 may comprise a plurality of individual integrated circuits 12 that have not yet been separated, separated, or diced from one another. Each integrated circuit 112 may comprise a memory device such as a NAND flash device.

[0018] The semiconductor substrate 20 may include any suitable semiconductor substrate. However, the semiconductor substrate 20 may include, but is not limited to, a semiconductor material, typically silicon, but may also use other semiconductor materials (e.g., gallium arsenide, indium phosphide, etc.). The semiconductor substrate 20 may consist of a semiconductor material, or it may comprise a layer of semiconductor material on a substrate formed from an electrical insulator such as glass (e.g., silicon-on-glass (SOG)) or sapphire (e.g., silicon-on-sapphire (SOS)). In examples where the semiconductor substrate 20 includes a wafer, the wafer may support a plurality of individual integrated circuits 12 that have not yet been diced from one another. Alternatively, the semiconductor substrate 20 may comprise a die or integrated circuit chip that is cut or diced from the wafer and supports a single integrated circuit 12.

[0019] The active layer 30 is manufactured together with and on the semiconductor substrate 20 and may include circuits 32 that define one or more integrated circuits 12 (Figure 2) on the semiconductor substrate 20. Furthermore, the active layer 30 may include a metal layer 34 on top of the circuits 32. The metal layer 34 may include structures that facilitate communication between the circuits 32 and electronic devices (not shown) outside each semiconductor device 10. For example, the bond pads of each individual semiconductor device 10 may be defined from the metal layer 34. In some examples, the metal layer 34 may include a plurality of sublayers that define bond pads, conductive traces, vias, etc. Such a metal layer 34 may define the redistribution layer (RDL) of each individual semiconductor device 10.

[0020] The protective layer 40 may include a patterned layer of dielectric material that electrically insulates and protects the underlying layers, including the metal layer 34 and the circuit 32 of the active layer 30. The protective layer 40 may be formed from polyimide patterned to expose any bond pads (not shown) of the metal layer 34 and the spaces between adjacent integrated circuits 12.

[0021] When a microcrack is formed in any of the layers of the semiconductor device 10, the microcrack may propagate across that layer or into an adjacent layer. For example, a microcrack generated from the semiconductor substrate 20 may spread to the active layer 30, a microcrack in the active layer 30 may spread to the protective layer 40, and a microcrack generated from the protective layer 40 may propagate into the active layer 30. Some microcracks within the semiconductor device 10 may affect the circuit of the semiconductor device 10 and potentially affect its ability to function properly. Other microcracks may not affect the circuit of the semiconductor device 10. However, over time, various factors may cause such microcracks to propagate into the circuit of the semiconductor device, ultimately leading to a chain of problems that can cause the semiconductor device 10 to fail. These factors include the thermal cycle of the semiconductor device 10 during repeated use, as well as forces acting on the semiconductor device 10 (e.g., shock due to vibration, impact, etc.).

[0022] Microcracks typically cannot be seen while imaging the semiconductor device 10 (e.g., with an X-ray imaging device, etc.). The damage they may cause is usually detected by electrically testing the circuit of the semiconductor device 10. Electrical testing reveals microcracks and other problems that affect the circuit of the semiconductor device 10, but electrical testing does not reveal microcracks that have not yet propagated into the circuit of the semiconductor device 10.

[0023] Figure 3 shows a process for facilitating the visual detection of microcracks in a semiconductor device. At reference numeral 310, a semiconductor substrate 120, such as a wafer, is provided. The semiconductor substrate 120 carries an active layer 130 (FIGS. 4 and 5) that includes a circuit 132 (FIG. 4) that defines a plurality of integrated circuits 112 (FIGS. 4 and 8) and a metal layer 134 (FIG. 4) that defines features (e.g., bond pads, conductive traces, vias, etc.) associated with each integrated circuit 112.

[0024] At reference numeral 312 in FIG. 3, an amount of dielectric material 142 in which the fluorescent indicator 144 (FIG. 4) is dispersed is applied to the active layer 130. The dielectric material 142 may be dispensed in liquid form. For example, the photopolymer 142 can include an uncrosslinked photimageable polymer such as polyimide.

[0025] As indicated by reference numeral 314, the photopolymer 142 can be spun onto the active layer 130 (FIG. 4) on the semiconductor substrate 120 by methods known in the art. By spinning the photopolymer 142 onto the active layer 130, the photopolymer can be actively spread across the active layer 130 to provide a photopolymer layer 142' of a desired thickness. The photopolymer layer 142' can then be patterned by methods known in the art to expose the desired portions (e.g., bond pads, etc.) of the metal layer 134 (FIG. 4), as well as the space between adjacent integrated circuits 112 (FIGS. 4 and 8), to facilitate their subsequent singulation from each other. The patterning of the photopolymer layer 142' defines a protective layer 140 over each integrated circuit 112.

[0026] FIG. 4 provides a cross-sectional view of a semiconductor device 110 having a protective layer 140 over the active layer 130. More specifically, the semiconductor device 110 includes a semiconductor substrate 120, an active layer 130 on the semiconductor substrate 120, and a protective layer 140 over the active layer 130. The protective layer 140 includes the fluorescent indicator 144. The semiconductor device 110 may include individual integrated circuits 112 singulated from other integrated circuits 112, or, as shown in FIG. 8, the semiconductor device 110 may include a plurality of individual integrated circuits 112 that are not yet singulated from each other. Each integrated circuit 112 can include a memory device such as a NAND flash device.

[0027] The semiconductor substrate 120 may include any suitable semiconductor substrate. The semiconductor substrate 120 may include semiconductor materials such as silicon or any other suitable semiconductor material (e.g., gallium arsenide, indium phosphide, etc.). The semiconductor substrate 120 may be composed of semiconductor material, or it may comprise a layer of semiconductor material on a substrate formed from an electrical insulator such as glass (such as SOG) or sapphire (such as SOS). In examples where the semiconductor substrate 120 includes a wafer, the wafer may carry a plurality of individual integrated circuits 112 that have not yet been diced from one another. Alternatively, the semiconductor substrate 120 may comprise a die or integrated circuit chip that is cut or diced from the wafer and carries a single integrated circuit 112.

[0028] The active layer 130 may be fabricated on and together with the semiconductor substrate 120 and may include circuits 132 that define one or more integrated circuits 112 on the semiconductor substrate 120. Furthermore, the active layer 130 may include a metal layer 134 on top of the circuits 132. The metal layer 134 may include structures that facilitate communication between the circuits 132 and electronic devices (not shown) located outside each semiconductor device 110. For example, the bond pads of each individual semiconductor device 110 may be defined from the metal layer 134. In some examples, the metal layer 134 may include a plurality of sublayers that define bond pads, conductive traces, vias, etc. Such a metal layer 134 may define the redistribution layer (RDL) of each individual semiconductor device 110.

[0029] The protective layer 140 may include a patterned layer of dielectric material 142 (e.g., polyimide). The dielectric material 142 can electrically insulate and protect the underlying layer, which includes the circuit 132 of the metal layer 134 and the active layer 130. A fluorescent indicator 144 is dispersed in the dielectric material 142. The fluorescent indicator 144 may constitute up to about 1% of the weight of the dielectric material 142.

[0030] More specifically, the dielectric material 142 may comprise polyamic acid, cyclohexane, a surfactant, a curing agent, one or more fillers, a plasticizer, and a fluorescent indicator 144. Polyamic acid is a precursor of polyimide. Cyclohexane is a solvent for the polyamic acid and the other components of the dielectric material. The surfactant improves the wetting of the dielectric material 142 and its components, helping the dielectric material 142 to uniformly coat the active layer 130. The curing agent promotes the intermolecular imidation reaction of the polyamic acid. The fillers impart mechanical strength and thermal conductivity to the dielectric material 142. The plasticizer can improve the flexibility and processability of the polyimide.

[0031] An example of the fluorescent indicator 144 is shown in Figure 5. The fluorescent indicator 144 may include microcapsules. Such a fluorescent indicator 144 may contain a shell 146 containing a fluorescent core 148. Such a fluorescent indicator 144 may have a diameter of about 1 μm to about 3 μm.

[0032] The fluorescent core 148 may include a material that emits fluorescence and visible radiation in images such as radiographs when exposed to a wavelength or bandwidth of radiation (e.g., X-ray radiation). The fluorescent core 148 may include a liquid.

[0033] The material of the shell 146 can limit the extent to which appropriate radiation (e.g., X-ray radiation) excites the fluorescent core 148 of the fluorescent indicator 144. In some examples, the material of the shell 146 can prevent such radiation from exciting the fluorescent core 148. The material of the shell 146 may be compatible with the dielectric material 142 (e.g., polyimide). The shell 146 may contain a polymer, but other suitable materials may also be used. The material of the shell 146 may interact with the dielectric material 142 (e.g., bonding, bonding, etc.) such that microcracks that intersect the shell 146 while microcracks are propagating can also propagate through the shell 146, causing the shell 146 to rupture.

[0034] When a microcrack ruptures the shell 146, the fluorescent core 148 is exposed. In the example where the fluorescent core 148 is liquid, the fluorescent core can flow out from the ruptured shell 146 into an adjacent microcrack 150 (Figure 7). When the exposed fluorescent core 148 is exposed to radiation of an appropriate wavelength or bandwidth (e.g., X-ray radiation), the fluorescent core 148 fluoresces, which can generate visible artifacts on an image or radiograph of the protective layer 140.

[0035] Figure 6 shows the semiconductor device 110 before the formation or propagation of microcracks. In this case, the semiconductor device 110 also includes a semiconductor substrate 120, an active layer 130, and a protective layer 140. The protective layer 140 is formed from a dielectric material 142 in which a fluorescent indicator 144 is dispersed. The image obtained under appropriate radiation looks the same as the image provided in Figure 2, and no microcracks are visible (in this case, because there are no microcracks in the protective layer 140).

[0036] In Figure 7, a microcrack 150 is formed in the semiconductor device 110'. More specifically, the microcrack 150 is formed in or propagates through the protective layer 140 of the semiconductor device 110'. As the microcrack 150 propagates through the protective layer 140', it intersects with some of the fluorescent indicators 144, causing their shells to rupture 146' and their fluorescent cores to be exposed 148'. In examples where the fluorescent cores 148' are liquid, the fluorescent cores can flow along the microcrack 150, including portions of the microcrack that extend into the active layer 130 of the semiconductor device 110'. A microcrack 150 in the active layer 130 extending to the top of the active layer 130 of the semiconductor device 100' can also activate fluorescent indicators 144 in portions of the protective layer 140 adjacent to such a microcrack 150.

[0037] Figure 8 provides an example of an image of the semiconductor device 110' obtained while the semiconductor device 110' is exposed to appropriate radiation (e.g., X-ray radiation). As shown in Figure 8, the exposed fluorescent core 148' illuminates microcracks 150a' and 150b' in the protective layer 140' and / or the portion of the active layer 130 adjacent to the protective layer 140', highlighting damage to the semiconductor device 110' that may not be apparent when the semiconductor device 110' is exposed to electrical testing prior to the assembly and packaging process.

[0038] Referring again to Figures 6-8, a method for determining whether microcracks have formed in semiconductor devices 110, 110' includes inspecting the semiconductor devices 110, 110'. The semiconductor devices 110, 110' can be inspected at any of the following points in time: before, during, and after packaging. For example, the semiconductor devices 110, 110' may be inspected before the semiconductor substrate 120 (e.g., a wafer) on which the semiconductor devices 110, 110' are manufactured is diced or cut to separate the individual integrated circuits 112 (Figure 4) from each other, i.e., before die fragmentation. As another example, the semiconductor devices 110, 110' can be inspected after they have been separated from other semiconductor devices 110, 110', or after they have been diced, or after die fragmentation. As yet another example, the semiconductor devices 110, 110' can be inspected before and after the packaging process (e.g., assembly, bonding, underfill, encapsulation, etc.). In some examples, the semiconductor devices 110, 110' may be inspected for microcracks 150 at multiple different points after the protective layer 140, 140' is applied, before the manufacturer ships the semiconductor devices 110, 110' or the package containing the semiconductor devices 110, 110' to the customer.

[0039] Inspection of semiconductor devices 110, 110' includes exposing semiconductor devices 110, 110' to radiation of an appropriate frequency or bandwidth (e.g., X-ray radiation) and acquiring images such as micrographs of semiconductor devices 110, 110' while irradiating them. Upon irradiation, any fluorescent indicator 144 within or along the microcracks 150 may be excited so that the microcracks 150 or a portion thereof can be visually distinguished from other locations on semiconductor device 110'.

[0040] For example, as shown in Figure 7, in an example where the fluorescent indicator 144 contains microcapsules, it is released by the fracture of the shell 146' by a microcrack 150, and the fluorescent core 148' that flows into the microcrack 150 can appear as a dark feature that is visually distinct from laterally adjacent features of the semiconductor device 110' in a micrograph, or magnified image, or more simply, a photograph of the semiconductor device 110', as shown in Figure 8. Thus, the fluorescent indicator 144 can make any microcrack 150 in the polyimide layer visible to an individual viewing an image of the semiconductor device.

[0041] Alternatively, as shown in Figure 6, if no microcracks are formed within or adjacent to the protective layer 140 of the semiconductor device 110, the fluorescent indicator 144 of the protective layer 140 of the semiconductor device 110 remains unaffected. Therefore, no microcracks are visible in the image of the semiconductor device 110. The image of such a semiconductor device 110 will look similar to the micrograph shown in Figure 2.

[0042] Radiographic imaging of semiconductor devices 110 and 110' can supplement conventional electrical testing of the semiconductor devices 110 and 110'. Semiconductor devices 110' that fail electrical testing can be examined radiographically to determine whether one or more microcracks were the cause of the failed electrical test(s). Similarly, semiconductor devices 110 and 110' that malfunction or fail during use can be examined radiographically to determine whether microcracks led to the malfunction or failure of the semiconductor devices 110 and 110'. Semiconductor devices 110 and 110' that pass electrical testing can be examined radiographically for microcracks to determine whether future microcrack-induced malfunctions or failures are possible or likely.

[0043] Based on the above, an example of the present disclosure describes a semiconductor device assembly comprising: a semiconductor substrate supporting a plurality of circuits; at least one metal layer on the semiconductor substrate; and a polyimide layer on at least one metal layer, wherein the polyimide layer contains a fluorescent indicator dispersed therethrough, and the bond pads of at least one metal layer are exposed through the polyimide layer. In one example, the fluorescent indicator constitutes up to about 1% of the weight of the polyimide layer. In one example, the fluorescent indicator comprises microcapsules having a fluorescent core and a shell. In one example, each fluorescent indicator comprises a microcapsule having a fluorescent core and a shell. In one example, each microcapsule of a plurality of microcapsules has a diameter of about 1 μm to about 3 μm. In one example, the semiconductor substrate comprises a wafer containing semiconductor material supporting a plurality of semiconductor devices. In one example, the metal layer comprises at least one redistribution layer. In one example, the semiconductor substrate comprises a die cut from the wafer containing the semiconductor material. In one example, the semiconductor device assembly also comprises a NAND memory device.

[0044] Another example describes a semiconductor device assembly comprising: semiconducting means for supporting a plurality of circuits; rewiring means for establishing communication between the plurality of circuits and an external electronic device of the semiconductor device; and protective means for insulating the rewiring means, the protective means comprising fluorescent means for identifying microcracks within the protective means, the fluorescent means being distributed throughout the protective means; and bonding means for establishing communication with an external electronic device of the semiconductor device, exposed through the protective means. In one example, the fluorescent means constitute up to about 1% of the weight of the protective means. In one example, the fluorescent means includes encapsulation means for containing a fluorescent material. In one example, the fluorescent means has a diameter of about 1 μm to about 3 μm. In one example, the semiconducting means includes a wafer containing semiconductor material. In one example, the semiconducting means includes a die cut from the wafer containing semiconductor material.

[0045] Further examples describe a method for detecting microcracks in semiconductor devices, the method comprising: forming a polyimide with a dispersed fluorescent indicator; applying the polyimide to a metal layer of multiple semiconductor devices on a wafer to form a polyimide layer with a dispersed fluorescent indicator; and X-ray imaging of at least one of the multiple semiconductor devices to provide an image of the at least one semiconductor device, wherein any microcracks in the at least one semiconductor device appear as dark lines in the image; and visualizing the image to identify microcracks in the at least one semiconductor device. In one example, forming the polyimide involves forming a polyimide with a fluorescent indicator that constitutes up to about 1% of the weight of the polyimide. In another example, forming the polyimide involves forming a polyimide having a fluorescent indicator that contains encapsulated fluorescent indicator. In one example, the microcrack extends through at least one microcapsule of the encapsulated fluorescent indicator, exposing the fluorescent material of at least one microcapsule. In another example, the fluorescent material flows into the microcrack from at least one microcapsule.

[0046] While this disclosure provides many details, these should not be construed as limiting the scope of any of the following claims, but merely as providing examples of some of the elements and features of the disclosed subject matter. Other examples of the disclosed subject matter, and other examples of their elements and features, may be devised without departing from the spirit or scope of any of the claims. Features from different examples may be used in combination. Thus, the scope of each claim is limited only by its plain language and its legal equivalents.

[0047] References to elements in this specification using designations such as "first," "second," etc., generally do not limit the number or order of those elements. Rather, these designations can be used as a way to distinguish two or more elements or instances of elements. Thus, references to first and second elements do not mean that only two elements may be used, or that the first element precedes the second element. Furthermore, unless otherwise specified, a set of elements may include one or more elements.

[0048] Terms used in the description or claims in the form of “at least one of A, B, or C” or “A, B, C, or any combination thereof” mean “A, B, or C, or any combination of these elements.” For example, this term may include A, or B, or C, or A and B, or A and C, or A and B and C, or 2A, or 2B, or 2C, or 2A and B, etc. As a further example, “at least one of A, B, or C” is intended to include A, B, C, AB, AC, BC, and ABC, as well as multiples of the same member. Similarly, “at least one of A, B, and C” is intended to include A, B, C, AB, AC, BC, and ABC, as well as multiples of the same member.

[0049] Similarly, as used herein, the phrase “and / or” referring to a list of linked items refers to any combination of items. For example, “A and / or B” is intended to include A only, B only, or A and B together. As another example, “A, B, and / or C” is intended to include A only, B only, C only, A and B together, A and C together, B and C together, or A, B and C together.

Claims

1. A semiconductor device assembly, A semiconductor substrate supporting multiple circuits, The semiconductor substrate comprises at least one metal layer, A polyimide layer on the at least one metal layer, wherein the polyimide layer contains a fluorescent indicator dispersed therethrough, and the bond pad of the at least one metal layer is exposed through the polyimide layer. A semiconductor device assembly comprising the above features.

2. The semiconductor device assembly according to claim 1, wherein the fluorescent indicator constitutes up to about 1% of the weight of the polyimide layer.

3. The semiconductor device assembly according to claim 1, wherein the fluorescent indicator comprises a microcapsule having a fluorescent core and a shell.

4. The semiconductor device assembly according to claim 3, wherein each fluorescent indicator comprises a microcapsule having a fluorescent core and a shell.

5. The semiconductor device assembly according to claim 3, wherein each of the plurality of microcapsules has a diameter of about 1 μm to about 3 μm.

6. The semiconductor device assembly according to claim 1, wherein the semiconductor substrate includes a wafer containing a semiconductor material on which a plurality of semiconductor devices are supported.

7. The semiconductor device assembly according to claim 1, wherein the metal layer includes at least one redistribution layer.

8. The semiconductor device assembly according to claim 1, wherein the semiconductor substrate includes a die cut from a wafer containing a semiconductor material.

9. A semiconductor device assembly according to claim 1, comprising a NAND memory device.

10. A semiconductor device assembly, Semiconductive means for supporting multiple circuits, Rewiring means for establishing communication between the plurality of circuits and an electronic device outside the semiconductor device, A protective means for insulating the rewiring means, the protective means comprising a fluorescent means for identifying microcracks within the protective means, the fluorescent means being distributed throughout the protective means, and bonding means for establishing communication with an external electronic device of the semiconductor device being exposed through the protective means, A semiconductor device assembly comprising the above features.

11. The semiconductor device assembly according to claim 10, wherein the fluorescent means constitutes up to about 1% of the weight of the protective means.

12. The semiconductor device assembly according to claim 11, wherein the fluorescent means includes encapsulation means for containing a fluorescent material.

13. The semiconductor device assembly according to claim 12, wherein the fluorescent means has a diameter of about 1 μm to about 3 μm.

14. The semiconductor device assembly according to claim 10, wherein the semiconductive means includes a wafer containing a semiconductor material.

15. The semiconductor device assembly according to claim 10, wherein the semiconducting means includes a die cut from a wafer containing a semiconductor material.

16. A method for detecting microcracks in semiconductor devices, The formation of a polyimide in which the fluorescent indicator is dispersed, The polyimide is applied to the metal layers of multiple semiconductor devices on a wafer to form a polyimide layer in which the fluorescent indicator is dispersed, The method involves X-ray imaging of at least one of the plurality of semiconductor devices to provide an image of the at least one semiconductor device, wherein any minute cracks within the at least one semiconductor device appear as dark lines in the image. A method comprising visualizing the image to identify the microcracks within the at least one semiconductor device.

17. The method according to claim 16, wherein forming the polyimide involves forming the polyimide using the fluorescent indicator which constitutes up to about 1% of the weight of the polyimide.

18. The method according to claim 16, wherein forming the polyimide comprises forming the polyimide having the fluorescent indicator, which includes an encapsulated fluorescent indicator.

19. The method according to claim 18, wherein the microcrack extends through at least one microcapsule of the encapsulated fluorescent indicator, exposing the fluorescent material of the at least one microcapsule.

20. The method according to claim 19, wherein the fluorescent material flows into the microcrack from the at least one microcapsule.

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