Method for testing packaging substrates and apparatus for testing packaging substrates

Abstract

To provide test methods and other tools suitable for rapidly and reliably testing complex microelectronic devices. [Solution] A method for testing a packaging substrate using at least one electron beam column is described, wherein the packaging substrate is a panel-level packaging substrate or an advanced packaging substrate. The method includes placing the packaging substrate on a stage in a vacuum chamber; directing at least one electron beam of at least one electron beam of at least one electron beam column onto at least a first portion of the packaging substrate; directing the at least one electron beam onto at least a second portion of the packaging substrate; detecting signal electrons emitted upon collision of the electron beam to test a first inter-device electrical interconnection path of the packaging substrate; and illuminating at least a third portion of the substrate with UV radiation.

Description

Technical Field

[0001] The present disclosure relates to a method and apparatus for testing a packaging substrate. More particularly, the embodiments described herein relate to non-contact testing of electrical interconnects within a packaging substrate, i.e., a panel-level packaging (PLP) substrate or an advanced packaging (AP) substrate, using an electron beam, and in particular to non-contact testing to identify and characterize defects such as shorts, opens, and / or leaks.

Background Art

[0002] In many applications, it is necessary to inspect substrates to monitor their quality. Since defects can occur, for example, during the processing of the substrate, such as during the construction or coating of the substrate, it may be beneficial to inspect the substrate to review the defects and monitor the quality.

[0003] Semiconductor packaging substrates and printed circuit boards for manufacturing complex microelectronics and / or micromechanical components are typically tested during and / or after manufacturing to determine defects such as shorts or opens in the metal paths and interconnects provided on the substrate. For example, a substrate for manufacturing a complex microelectronic device may include a plurality of interconnect paths for connecting semiconductor chips or other electrical devices mounted on a packaging substrate.

[0004] Various methods for testing such components are known. For example, to determine whether a component under test has a defect, the contact pads of the component may be contacted with contact probes. As components are becoming smaller and smaller due to miniaturization, it may be difficult to contact the contact pads with contact probes, and moreover, there may even be a risk that the device under test is damaged during testing.

[0005] The complexity of packaging substrates is increasing, and design rules (feature size) are becoming significantly smaller. Within such substrates, surface contacts (for later flip-chip mounting or other chip mounting) are connected to other surface contacts on the packaging substrate to interconnect semiconductor devices (or other devices). Standard methods such as electromechanical exploration for electrical testing cannot meet the requirements of mass production testing due to reduced throughput (increased number of test points) and decreased contact reliability (smaller contact size). Beyond the issues of size reduction and potential damage to contact pads, topography of packaging substrates presents difficulties for other test methods, such as those utilizing capacitive or field detectors, because such methods benefit from small mechanical spacing. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Therefore, it would be beneficial to provide test methods and test equipment suitable for rapidly and reliably testing complex microelectronic devices, particularly packaging substrates such as AP substrates and PLP substrates.

[0007] Taking the above into consideration, a method and apparatus for testing a packaging substrate are provided according to the independent claim. Additional embodiments, advantages and beneficial features are evident from the dependent claims, description and accompanying drawings. [Means for solving the problem]

[0008] According to one embodiment, a method is provided for testing a packaging substrate using at least one electron beam column. The packaging substrate is a panel-level packaging substrate or an advanced packaging substrate. The method includes: placing the packaging substrate on a stage in a vacuum chamber; directing at least one electron beam of at least one electron beam of at least one electron beam column onto at least a first portion of the packaging substrate; directing at least one electron beam of at least one electron beam of at least one electron beam column onto at least a second portion of the packaging substrate; detecting signal electrons emitted upon collision of at least one electron beam to test a first inter-device electrical interconnection path of the packaging substrate; and illuminating at least a third portion of the packaging substrate with UV radiation.

[0009] According to one embodiment, an apparatus is provided for testing a packaging substrate according to any of the methods described herein.

[0010] According to one embodiment, an apparatus for non-contact testing of a packaging substrate is provided. The apparatus comprises a vacuum chamber, a stage within the vacuum chamber, the stage configured to support a packaging substrate which is a panel packaging substrate or an advanced packaging substrate, and a charged particle beam column configured to generate an electron beam, the electron beam column comprising an objective lens configured to focus the electron beam onto the packaging substrate, a scanner configured to scan the electron beam at different locations on the packaging substrate, and an electron detector for detecting signal electrons emitted when the electron beam strikes the packaging substrate, the apparatus further comprises a UV source assembly configured to illuminate the packaging substrate in the vacuum chamber with one or more UV emission pulses, and an analysis unit for determining, based on the signal electrons, whether a first inter-device electrical interconnection path is defective.

[0011] The embodiments also cover apparatus for performing the disclosed methods, including apparatus components for performing each of the described method embodiments. These method embodiments may be performed as hardware components, as a computer programmed with appropriate software, in any combination of these two, or in any other manner. Furthermore, the embodiments provided herein also cover methods for operating the described apparatus, as well as methods for manufacturing the apparatus and devices described herein. Methods for operating the described apparatus include method embodiments for performing any function of the apparatus.

[0012] To gain a more detailed understanding of the features of this disclosure listed above, a more detailed description of the disclosure outlined above can be obtained by referring to the embodiments. The attached drawings relate to embodiments of this disclosure, and a description of the attached drawings is given below. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic cross-sectional view of an apparatus for testing a packaging substrate according to one of the test methods described herein. [Figure 2A] This is an enlarged cross-sectional view of a packaging substrate during one of the test methods described herein. [Figure 2B] This is an enlarged cross-sectional view of a packaging substrate during one of the test methods described herein. [Figure 3] This is an enlarged top view of a packaging substrate during one of the test methods described herein. [Figure 4A] This is an enlarged cross-sectional view of a packaging substrate that can be tested according to the method described herein. [Figure 4B] This is an enlarged cross-sectional view of a packaging substrate that can be tested according to the method described herein. [Figure 4C] This is an enlarged cross-sectional view of a packaging substrate that can be tested according to the method described herein. [Figure 4D] This is an enlarged cross-sectional view of a packaging substrate that can be tested according to the method described herein. [Figure 5] This is a flowchart illustrating a method for testing a packaging substrate according to the embodiments described herein. [Figure 6] This is a flowchart illustrating a method for testing a packaging substrate according to the embodiments described herein. [Figure 7A] This figure shows an exemplary image illustrating an improvement to the embodiments of the disclosure. [Figure 7B] This figure shows an exemplary image illustrating an improvement to the embodiments of the disclosure. [Modes for carrying out the invention]

[0014] Next, various exemplary embodiments will be referenced in detail. One or more examples of these embodiments are shown in each figure. Each example is provided for illustrative purposes only and is not intended to be limiting. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to create additional embodiments. This disclosure is intended to include such modifications and variations.

[0015] In the following description of the drawings, the same reference numerals refer to the same components. Only differences relating to individual embodiments are described. The structures shown in the drawings are not necessarily drawn at a uniform scale, which is rather helpful for a better understanding of the embodiments.

[0016] Embodiments of the present disclosure relate to testing and / or defect review of a packaging substrate, i.e., a panel level packaging (PLP) substrate or an advanced packaging (AP) substrate, by the methods described herein. At least one electron beam is used to write charge on the packaging substrate and read the charge on the packaging substrate, in particular for the purpose of identifying and characterizing defects such as short circuits, open circuits and / or leaks, and writing and reading the charge. According to some embodiments that can be combined with other embodiments described herein, the voltage contrast on the packaging substrate may be determined by detecting signal electrons. Charge control is provided to further improve the voltage contrast in the methods according to embodiments of the present disclosure and in the devices according to embodiments of the present disclosure. The packaging substrate can be discharged to defined conditions.

[0017] According to one embodiment, a method for testing a packaging substrate is provided. The packaging substrate is a panel level packaging substrate or an advanced packaging substrate. The method implemented using at least one electron beam column includes placing the packaging substrate on a stage within a vacuum chamber. The method further includes directing at least one electron beam of the at least one electron beam column onto at least a first portion of the packaging substrate and directing at least one electron beam of the at least one electron beam column onto at least a second portion of the packaging substrate. To test a first inter-device electrical interconnect path of the packaging substrate, signal electrons emitted upon collision of the at least one electron beam are detected. The at least third portion of the packaging substrate is irradiated with UV radiation. For example, the at least third portion can include the first portion and the second portion. In particular, the at least third portion can be the packaging substrate or can include the packaging substrate. The first portion and the second portion may overlap. However, according to some embodiments that can be combined with other embodiments described herein, the first portion can be one or more first surface contacts onto which charge is written. The second portion can be one or more second surface contacts from which charge is read.

[0018] According to some embodiments that can be combined with other embodiments described herein, at least one electron beam is directed onto the at least first portion with a first incident energy and onto the at least second portion with a second incident energy different from the first charged incident energy. For example, signal electrons can be detected when at least one electron beam collides with a second energy for reading charge on the packaging substrate.

[0019] To reduce the space requirements of semiconductor packages, the complexity of packaging substrates has continued to increase over the years. To reduce manufacturing costs, 2.5D ICs, 3D-ICs, and packaging techniques such as wafer-level packaging (WLP), e.g., fan-out WLP, have been proposed. In WLP techniques, integrated circuits are packaged before dicing. As used herein, "packaging substrate" refers to a packaging substrate configured for advanced packaging techniques, particularly WLP techniques or panel-level packing (PLP) techniques.

[0020] "2.5D integrated circuits" (2.5D ICs) and "3D integrated circuits" (3D ICs) combine multiple dies within a single integrated package. Here, two or more dies are placed on a packaging substrate, such as a silicon interposer or panel-level packaging substrate. In 2.5D ICs, the dies are placed side-by-side on the packaging substrate, while in 3D ICs, at least some of those dies are placed on top of each other. The assembly can be packaged as a single component, thereby reducing cost and size compared to conventional 2D circuit board assemblies.

[0021] A packaging substrate typically includes multiple inter-device electrical interconnection paths for providing electrical connections between chips or dies placed on the packaging substrate. These inter-device electrical interconnection paths may extend vertically (perpendicular to the surface of the packaging substrate) and / or horizontally (parallel to the surface of the packaging substrate) in a complex network of connections through the body of the packaging substrate, with their endpoints (referred to herein as surface contacts) exposed on the surface of the packaging substrate.

[0022] Advanced packaging (AP) substrates provide electrical interconnection paths between devices on a wafer, for example, on a silicon wafer, or within a wafer, for example, within a silicon wafer. For example, an AP substrate may include through-silicon vias (TSVs), which are other conductors extending through the AP substrate, such as through-silicon vias (TSVs) provided within a silicon interposer. Panel-level packaging substrates are provided from composite materials, for example, from printed circuit board (PCB) materials, or from other composite materials, for example, ceramic and glass materials.

[0023] Panel-level packaging substrates are manufactured that are configured to integrate multiple devices (e.g., chips / dies that may be heterogeneous, e.g., chips / dies that may have different sizes and configurations) into a single integrated package. Furthermore, AP substrates may be bonded to the PLP substrate. The panel-level substrate typically provides its surface, for example, portions for multiple chips, dies, or AP substrates placed on one or both sides thereof, and multiple inter-device electrical interconnection paths extending through the body of the PLP substrate.

[0024] It should be noted that the size of the panel-level substrate is not limited to the size of the wafer. For example, the panel-level substrate may be rectangular or have other shapes. Specifically, the panel-level substrate may have a larger surface area than a typical wafer, for example, 1000 cm². 2 The above surface area may be provided. For example, the panel-level substrate may have a size of 30cm x 30cm or larger, 60cm x 30cm or larger, or 60cm x 60cm or larger.

[0025] According to embodiments of this disclosure, E-beam testing and / or E-beam review can provide testing of contact pads 60 μm or less, or even about 10 μm or less. Voltage contrast testing imaging can be provided. Testing can be provided at or between "surface contacts" of the packaging substrate.

[0026] A “surface contact” may be understood as an endpoint of an electrical interconnection path exposed on the surface of a packaging substrate in such a manner that an electron beam can be directed onto the surface contact for contactless charging or exploration of the electrical interconnection path. The surface contact is configured to make electrical contact with chips, dies, smaller packages or other electrical components, such as capacitors, resistors, coils or other similar components, which are placed on the surface of the packaging substrate, for example, by soldering. The electrical components may further include active electrical components, such as transformers that change the voltage in a region of the package. In some embodiments, the surface contact may be a solder bump or may include solder bumps.

[0027] According to embodiments of this disclosure, 100% of the electrical interconnection paths are tested. The cost of ownership of a device package, including chips such as processors, memory or other similar devices (microelectronic devices), is primarily determined by the high-integration microelectronic devices themselves. Therefore, mounting defect-free microelectronic devices on a defective packaging substrate is disadvantageous in terms of manufacturing costs. It is desirable that the packaging substrate be completely defect-free before mounting the microelectronic devices.

[0028] This disclosure relates to a method and apparatus for testing a packaging substrate configured to integrate multiple devices into a single integrated package, and which includes at least one inter-device electrical interconnection path. According to embodiments of this disclosure, a test system, test apparatus, or test method may detect and / or classify defective electrical connections in the packaging substrate, such as open circuits, short circuits, leakage defects, or others. In particular, these test methods and test systems may provide non-contact testing. Contact pad pitches of 60 μm or less, or even about 10 μm or less, are difficult, or even impossible, to test with mechanical methods. Furthermore, these small contact pads must not be damaged by scratching. Non-contact testing is beneficial.

[0029] According to several embodiments that can be combined with other embodiments described herein, charge control during charge writing can be provided by operating the electron beam column at a specified incident energy. In particular, the incident energy, i.e., the energy of the electron beam at the time of impact with the packaging substrate, can be changed to control the charge supplied to the packaging substrate. By changing the incident energy, the electron beam impact area can be positively or negatively charged, or left uncharged. Beneficially, no charge is supplied to the packaging substrate during the writing operation. Non-contact electrical testing can be provided using the e-beam, in which charge can be placed, for example, at a first surface contact and read at, for example, a second surface contact. This enables the detection and classification of electrical defects in the packaging substrate. Different e-beam incident energies (UPe) control the SE yield (secondary electron yield) and therefore the total electron yield. On several substrates, and / or after repeating the e-beam scanning and testing sequence, it is beneficial to discharge the test substrate to specified conditions, such as starting conditions with respect to potential and charge distribution, in order to achieve a voltage contrast signal with good reproducibility.

[0030] According to several embodiments that can be combined with other embodiments described herein, a method for testing a package includes: placing a package substrate on a stage in a vacuum chamber; directing an electron beam from at least one electron beam column onto at least a first portion of the package substrate with a first incident energy; and directing an electron beam from at least one electron beam column onto the package substrate with a second incident energy different from the first incident energy. The method further includes detecting signal electrons emitted upon electron beam impact to test at least a first inter-device electrical interconnection path of the package substrate. According to embodiments of the present disclosure, illuminating at least a third portion of the package substrate with UV radiation can provide a discharge in at least one portion. This can provide a defined potential and / or charge distribution. This may be repeated once or multiple times during testing of the package substrate. In particular, multiple discharges by UV radiation may be provided in a test sequence for testing the package substrate.

[0031] We can provide testing of the characteristics of a packaging substrate, for example, testing of the electrical interconnection paths of a packaging substrate, and in doing so, we can control the characteristics and / or the charging of the packaging substrate. e-beam primary energy (U pe), that is, by utilizing the change in the incident energy of the electron beam incident on the packaging substrate, the charge on the packaging substrate, or the charge on each part of the packaging substrate, can be controlled. UV radiation is used to discharge the packaging substrate, that is, to remove the previously provided charge or the charge accumulated on the packaging substrate before the test procedure. Thus, an improved non-contact electrical test using an electron beam can be provided. The test may include reading a voltage signal, i.e., measuring the voltage contrast when detecting signal electrons, e.g., secondary electrons. To avoid damage to surface contacts, the test location, i.e., the surface contacts, of the advanced packaging substrate or panel-level packaging substrate can be charged non-contact. The charge can be removed by the photo effect generated by UV radiation.

[0032] Figure 1 shows a schematic cross-sectional view of an apparatus 100 for testing a packaging substrate 10 according to an embodiment described herein. The apparatus 100 includes a vacuum chamber 101, which may be a test chamber specifically configured for testing, or one of the vacuum chambers in a larger vacuum system, such as a processing chamber in a packaging substrate manufacturing system or a packaging substrate processing system.

[0033] As schematically shown in Figure 1, the packaging substrate 10 includes a first inter-device electrical interconnection path 20 extending between a first surface contact 21 and a second surface contact 22 of the packaging substrate 10. Optionally, the first inter-device electrical interconnection path 20 may extend between three or more surface contacts, which may be provided on the same surface of the packaging substrate or on two opposite surfaces. Although the inter-device electrical interconnection path 20 shown in Figure 1 extends only between the first surface contact 21 and the second surface contact 22, both located on the top surface of the packaging substrate, the disclosure is not limited to such an inter-device electrical interconnection path, and the inter-device electrical interconnection path may be a complex network of vias, pillars, and / or wires extending through the packaging substrate and having multiple surface contacts.

[0034] The packaging substrate 10 may include multiple inter-device electrical interconnection paths 20 for connecting multiple devices placed on the packaging substrate 10. Although three inter-device electrical interconnection paths are shown exemplarily in Figure 1, the packaging substrate 10 may include thousands or tens of thousands of inter-device electrical interconnection paths that are typically electrically isolated from each other, as long as there is no short circuit between any two electrical interconnection paths.

[0035] According to embodiments described herein, the packaging substrate 10 is placed on a stage 105 in a vacuum chamber 101. The stage can be movable, and in particular, it can be movable in the z direction (i.e., perpendicular to the stage surface) and / or in the x and y directions (i.e., in the plane of the stage surface). The stage 105 is provided in a vacuum chamber and is configured to support a packaging substrate, which is either a panel-level packaging substrate or an advanced packaging substrate. An electron beam 111 is guided onto a first surface contact 21. The electron beam can be scanned and guided to a second surface contact 22. Signal electrons 113 emitted from the second surface contact 22 are detected to test the first inter-device electrical interconnection path 20. The signal electrons may be secondary electrons and / or backscattered electrons. For example, it can be determined whether the first inter-device electrical interconnection path 20 has an "open circuit" defect.

[0036] Alternatively, or in addition to that, the electron beam 111 is directed onto an additional surface contact 27 that is not an endpoint of the first inter-device electrical interconnection path 20, i.e., an additional surface contact 27 belonging to a second inter-device electrical interconnection path 23 that may extend through a packaging substrate adjacent to the first inter-device electrical interconnection path 20. To test the first inter-device electrical interconnection path 20, signal electrons emitted from the additional surface contact 27 are detected. The signal electrons may be secondary electrons and / or backscattered electrons. For example, it can be determined whether the first inter-device electrical interconnection path 20 has a “short circuit” defect.

[0037] In particular, by detecting the signal electrons 113 emitted when the electron beam 111 strikes the packaging substrate (especially by determining the energy of the signal electrons 113, which depends on the potential of the second surface contact 22 or additional surface contact 27), it is possible to determine in "voltage contrast measurement" whether the first inter-device electrical interconnection path 20 has defects. Specifically, it is possible to determine and classify defective connections within the packaging substrate, for example, into open circuits, short circuits, and / or leakage defects.

[0038] In some embodiments, which can be combined with other embodiments described herein, one or more electrical connections extending between surface contacts on different sides of a substrate are inspected. In additional embodiments, a first plurality of electrical connections extending between surface contacts on a first side of the substrate, a second plurality of electrical connections extending between surface contacts on a second side of the substrate, and / or a third plurality of electrical connections extending between surface contacts on different faces of the substrate are inspected. For example, one or more electron beam columns may be positioned on both sides of the substrate so that the surface contacts on both sides of the substrate can be charged and / or discharged to inspect and test each electrical connection (not shown).

[0039] According to the embodiments described herein, both charging and exploration are provided using an electron beam, particularly a scanning electron beam. Other test methods, such as electrical and / or mechanical exploration, cannot provide the throughput offered by the methods and systems described herein. The methods and systems described herein rely on non-contact charging and exploration using an electron beam. Furthermore, the contact reliability of electrical and / or mechanical testers decreases with decreasing size of surface contacts of the test object within the advanced packaging substrate, as well as increasing density and number of surface contacts. For example, contact pad sizes of 30 μm or less are difficult for mechanical exploration. In addition, with respect to other inspection methods such as capacitive detectors or field detectors, the topography of the packaging substrate and the topography of surface contacts of the packaging substrate may also pose problems. Having a charging electron beam is even more advantageous than, for example, flood gun electron charging. Given the complexity of the packing substrate, the capacitance of local charging improves the available test procedures compared to charging an entire area using a flood gun. Furthermore, local charging reduces the overall charge accumulated on the packing substrate. Furthermore, different charging in different areas may result in a reduction of the overall charge provided on the substrate. For example, if one area is positively charged and another area is negatively charged, the overall charge can be kept near neutral. According to several embodiments that can be combined with other embodiments described herein, different charge patterns can be provided in multiple parts of the packaging substrate. According to embodiments of this disclosure, charge can be removed. For example, discharge of a localized area can be provided by having a locally adapted lateral distribution of UV radiation intensity or the duration of one or more UV radiation pulses.

[0040] The test method described herein is suitable for testing packaging substrates for multi-device-in-package integration, and in particular for testing panel-level packaging substrates (PLP substrates) or advanced packaging substrates (AP substrates), and uses an e-beam for both the purpose of charging the inter-device electrical interconnection paths 20 and for the purpose of reading the voltage of the charged circuits, in particular by exploring second surface contacts and / or additional surface contacts. In other words, using an electron beam, both "electrical driving" and "exploration" are performed in a manner that allows for the rapid and highly reliable detection of defects. Testing by e-beam charging and e-beam exploration (e.g., using an EBT column or EBR column) is independent of topography, is fast, and offers flexibility with respect to contact location, size, and shape dimensions, whereas other test methods, such as capacitive detectors or field detectors, may involve issues with the topography of the packaging substrate.

[0041] Packing substrates such as PLP substrates may contain multiple inter-device connections, e.g., 5,000 or more, 10,000 or more, 20,000 or more, or even 50,000 or more. These connections may include through-silicon vias (TSVs), e.g., through-silicon vias provided within a silicon interposer, other wires extending through the packaging substrate, and / or multi-die interconnect bridges that may be embedded in the packaging substrate. The packaging substrate may be a multilayer substrate containing electrical interconnections within multiple layers arranged on top of each other, e.g., within a layer stack.

[0042] In some embodiments, the packaging substrate 10 includes a plurality of inter-device electrical interconnection paths extending between each first and second surface contact and an optional additional contact, and the method may include testing those plurality of inter-device electrical interconnection paths sequentially or in parallel. As used herein, “sequential testing” refers to the successive testing of a plurality of inter-device electrical interconnection paths of the packaging substrate. For example, testing 5,000 or more inter-device electrical interconnection paths sequentially. As used herein, “parallel testing” may refer to the synchronous testing of two or more inter-device electrical interconnection paths. As used herein, “parallel testing” may also refer to testing several inter-device electrical interconnection paths by scanning an electron beam over several first surface contacts to charge one field of view, while simultaneously scanning the electron beam over several corresponding second surface contacts to explore one field of view.

[0043] In some embodiments, guiding the electron beam 111 onto a first surface contact includes focusing the electron beam 111 onto the first surface contact 21, for example, focusing it so that the beam probe diameter on the packaging substrate is 30 μm or less, particularly 10 μm or less. Focusing the charged electron beam onto the packaging substrate using, for example, an objective lens, can prevent charging of substrate surface areas different from the surface contacts, thereby providing more accurate test results. The electron beam may be scanned across the portion of the packaging substrate to generate an image of the portion of the packaging substrate, or in addition to, or instead of, generating an image of the portion of the packaging substrate, particularly to detect the signal electron beam. The image may include voltage contrast information. For example, pattern recognition within the image can provide defect detection or classification of one or more electrical interconnection paths.

[0044] Conventional PCBs typically include relatively large planar metal pads that form surface contacts for testing. However, packaging substrates tested according to the embodiments described herein may contain a vast number of small convex solder bumps, which makes testing more difficult. In particular, the first surface contact 21 and the second surface contact 22 may each have a maximum dimension of 25 μm or less, especially 10 μm or less. For example, the first and second surface contacts may be spherical, especially hemispherical, with a diameter of 25 μm or less, especially 10 μm or less. According to some embodiments that can be combined with other embodiments described herein, the surface contacts may have a three-dimensional topography, especially a substantially hemispherical three-dimensional topography.

[0045] In contrast to mechanical testers, the electron beam can be focused to a very small probe diameter and guided precisely to a predetermined point on the substrate, for example using a scanning deflector, with an accuracy of, for example, sub-micrometer range, so that the electron beam can be precisely guided over such small surface areas. While other testers may slip or slide over surface contacts with convex shape dimensions, the electron beam can be precisely focused over any shape dimension in such a manner that the test methods described herein are shape dimension independent and topography independent.

[0046] As schematically shown in Figure 1, a charged particle beam column 120 may be provided on the first side of the stage 105. In some embodiments that can be combined with other embodiments described herein, the charged particle beam column 120 may have an electron source 121 for generating an electron beam and beam optics elements, such as a scanning deflector 122 and / or an objective lens 124, for guiding the first electron beam onto a substrate placed on the stage 105. The objective lens 124 may be an electrostatic objective lens (shown in Figure 1), a magnetic objective lens, or a magneto-electrostatic objective lens.

[0047] The apparatus 100 further includes an electron detector 140 for detecting signal electrons 113 emitted when a second electron beam strikes a packaging substrate, and an analysis unit 141 configured to determine, based on the signal electrons 113, whether the first inter-device electrical interconnect path 20 is defective. In some embodiments, the analysis unit 141 may be configured to determine, based on the detected signal electrons, whether the electrical interconnect path has defects such as short circuits, open circuits and / or leaks. Optionally, the analysis unit 141 may be configured to classify the detected defects. In some embodiments, the analysis unit 141 may be configured to determine, based on the detected signal electrons from subsequent measurements, whether a short circuit or leak exists between two or more electrical interconnect paths. In some embodiments, the signal electrons 113 detected by the electron detector 140 may also provide information about the potential at the substrate location from which the signal electrons 113 were emitted or reflected, and the analysis unit 141 may be configured to determine, from this information, whether the first inter-device electrical interconnect path 20 is defective. The analysis unit 141 may be further configured to classify the determined defects. Specifically, testing may include the analysis unit 141 determining whether the first inter-device electrical interconnection path 20 has any of the following: short circuit, open circuit, and / or leakage. An "open circuit" is understood as an open electrical interconnection path that does not actually electrically connect the first surface contact 21 and the second surface contact 22. A "short circuit" is understood as an electrical connection between two electrical interconnection paths that should actually be electrically isolated.

[0048] In some embodiments, which can be combined with other embodiments described herein, the electron detector 140 includes an Everhard-Thornley detector. As schematically shown in Figure 1, an energy filter 142 for signal electrons 113 may be positioned before the electron detector 140, and in particular before the Everhard-Thornley detector. The energy filter may include a lattice electrode configured to be set to a predetermined potential. The energy filter 142 may allow suppression of low-energy signal electrons. The energy filter 142 may suppress signal electrons unrelated to the voltage contrast measurement being performed. In some embodiments, the energy filter 142 may suppress signal electrons emitted from uncharged surface areas and allow only signal electrons emitted from charged surface contacts to pass through. Thus, the signal current detected by the electron detector may depend on the energy of the signal electrons indicating whether the surface contact being explored has a defect or not.

[0049] In some embodiments, the apparatus 100 may include a scanning controller 123 connected to a scanning deflector 122 of a charged particle beam column 120. The scanning deflector 122 may be configured to scan an electron beam over a substrate surface. The electron beam may be guided over a portion of the packaging substrate, for example, by a first beam probe diameter. The portion of the packaging substrate can be an area of ​​the packaging substrate or the entire area of ​​the packaging substrate over which the electron beam is scanned. The electron beam can be raster scanned over that portion of the packaging substrate. For example, one or more scanning deflectors 122 can scan the electron beam over that portion of the packaging substrate. The portion of the packaging substrate may be a surface contact. The electron beam can be vector scanned to one or more surface contacts of the packaging substrate. For example, one or more scanning deflectors can be used to wake-scan the electron beam to one or more surface contacts.

[0050] For example, the scanning controller 123 may be configured to control the scanning deflector such that the electron beam is sequentially guided to each pair of first and second surface contacts in order to test each inter-device electrical interconnection path extending between each pair of first and second surface contacts. This enables rapid and reliable inspection of multiple electrical interconnection paths extending through the packaging substrate.

[0051] According to some embodiments that can be combined with other embodiments described herein, the electron beam can be vector-scanned to individual locations, e.g., surface contacts of the packaging substrate, for charging purposes, and the electron beam can be vector-scanned to individual locations for detecting signal electrons. Alternatively, the electron beam can be vector-scanned to individual locations, e.g., surface contacts of the packaging substrate, for charging purposes, and the electron beam can be raster-scanned over an area of ​​the packaging substrate for detecting signal electrons. According to some embodiments that can be combined with other embodiments described herein, the electron beam of a charged particle beam column can be scanned to one or more locations on the packaging substrate for charging purposes and for detecting signal electrons.

[0052] As schematically shown in Figure 1, the electron source 121 is connected to a power supply 130. The power supply can provide the electron source with a high voltage to emit an electron beam, i.e., a primary electron beam. According to some embodiments that can be combined with other embodiments described herein, the voltage provided by the power supply 130 can be changed to alter the energy of the electron beam, and therefore the incident energy of the electron beam incident on the packaging substrate. According to some embodiments that can be combined with other embodiments described herein, one or more power supplies can be connected to various components of the electron beam column. For example, power supplies can be connected to the electron source (shown in Figure 1), the extraction electrode of the electron source, the anode of the electron source, a deceleration electrode configured to decelerate electrons before they collide with the packaging substrate, and / or the stage 105. The incident energy of the electron beam incident on the packaging substrate is determined by the potential difference between the potential of the emitter tip of the electron source and the potential of the packaging substrate or the potential of the stage 105, respectively. Thus, one or more power supplies can be provided to alter the incident energy of the electron beam.

[0053] As shown in Figure 1, the apparatus 100 may include one or more UV sources 170, for example, UV sources that generate UV radiation. One or more UV sources 170 may be placed in the vacuum chamber 110. For example, one or more UV sources 170 may be arranged to enable uniform illumination of the test area of ​​the charged particle beam column 120. The illumination area 172 of the UV sources is shown in Figure 1.

[0054] According to several embodiments that can be combined with other embodiments described herein, a vacuum ultraviolet (VUV) light source can be provided to control the charge of all test points (surface contacts) on the AP or PLP substrate. The UV source can be integrated within the charged particle beam column and / or within the vacuum chamber 110. The field of view (FOV) of the charged particle beam column, i.e., the SEM FOV, can be irradiated before the electron beam test sequence, particularly immediately before, during, or after the electron beam test sequence. In particular, areas of the packaging substrate, such as the FOV, can be irradiated without mechanical movement of the substrate, for example, without mechanical movement of the substrate by the stage CV.

[0055] The apparatus 100 includes a shutter 175. The shutter 175 may be a mechanical shutter. The shutter is configured to turn the UV radiation of the illumination area 172 on or off. According to several embodiments which can be combined with other embodiments described herein, the UV radiation can be rapidly turned on / off or pulsed. For example, the UV radiation pulse may be 500 milliseconds or less, e.g., 100 milliseconds or less. In particular, the UV radiation pulse may be 10 milliseconds or less. One or more UV radiation pulses can be provided by pulsing the UV source or by the mechanical shutter. According to several embodiments which can be combined with other embodiments described herein, the method may include moving the shutter while illuminating a packaging substrate with UV radiation to provide UV radiation pulses.

[0056] According to several embodiments that can be combined with other embodiments described herein, the wavelength of the UV radiation can be 200 nm or less, particularly 170 nm or less. In addition, or instead, a gas discharge tube can be used to generate the radiation. For example, a xenon lamp, mercury lamp, deuterium lamp or other similar lamp may be used. It may be beneficial to operate the gas discharge lamp in continuous operation mode. According to several embodiments that can be combined with other embodiments described herein, a shutter configured to provide UV radiation pulses may be beneficial. The UV source 170 and the shutter may be included in a UV source assembly, or the UV source 170 and the shutter may form a UV source assembly.

[0057] According to several embodiments that can be combined with other embodiments described herein, the UV source 170, such as a VUV source, can be made replaceable from outside the column or from outside the vacuum chamber. Since UV sources have a limited lifespan, the replacement of one or more UV sources from outside the vacuum atmosphere improves the maintenance cycle. For example, UV light can be guided into the charged particle beam column and / or vacuum chamber through a magnesium window.

[0058] According to one embodiment, an apparatus for non-contact testing of a packaging substrate is provided. The packaging substrate is a panel packaging substrate or an advanced packaging substrate. The apparatus includes a vacuum chamber 101 and a stage 105 within the vacuum chamber, the stage configured to support the packaging substrate, which is a panel packaging substrate or an advanced packaging substrate. The apparatus further includes an electron beam column configured to generate an electron beam, the electron beam column including an objective lens configured to focus the electron beam onto the packaging substrate, a scanner configured to scan the electron beam at different locations on the packaging substrate, and an electron detector for detecting signal electrons emitted when the electron beam strikes the packaging substrate. The electron beam column may further include one or more power supplies for changing the incident energy of the electron beam column. The apparatus further includes a UV source assembly configured to illuminate the packaging substrate in the vacuum chamber with UV emission pulses, and an analysis unit for determining, based on signal electrons, whether a first inter-device electrical interconnection path is defective.

[0059] According to some embodiments which can be combined with other embodiments described herein, a UV source assembly includes a UV source for generating UV radiation and a movable shutter for generating one or more UV radiation pulses.

[0060] Figure 1 illustrates a grounded stage 105. The stage may be grounded directly, grounded via a DC power supply as illustrated in Figure 1, or grounded via an AC power supply. According to some embodiments which can be combined with other embodiments described herein, the stage may include a conductive stage surface that is grounded directly or indirectly to provide a reference potential.

[0061] When a packaging substrate is placed on the stage 105, the packaging substrate has a defined charge provided on it. Notwithstanding this, the stage can be conductive. Thus, the stage can be provided with a defined potential. For example, the defined potential may be the ground potential, or it may be a negative or positive potential relative to ground. For example, a DC power supply can be provided between ground and the conductive stage. Alternatively, an AC power supply can be provided between ground and the conductive stage, in which case a defined alternating potential can be provided. According to some embodiments that can be combined with other embodiments described herein, a non-conductive material is provided on the surface of the stage 105. For example, a dielectric material layer can be provided as the surface of the stage. Having a non-conductive stage surface makes it possible to add and maintain a charge on the packaging substrate for detection during a test operation or defect review operation.

[0062] A defined potential on the stage, particularly a conductive stage, provides an electric field line, especially on the stage surface and the non-conductive portion of the packaging substrate. This defined potential can be used to influence the electron beam of an electron beam column.

[0063] According to additional embodiments that can be combined with other embodiments described herein, capacitive coupling between the packaging substrate and the stage 105 can provide a packaging substrate at a defined potential. For example, a grounded conductive stage 105 can provide capacitive coupling to earth. In addition, or instead, a predetermined set of structures on the packaging substrate may be grounded. However, the predetermined set of structures does not have to be charged by grounding and may serve as a reference potential.

[0064] According to several embodiments that can be combined with other embodiments described herein, one or more illumination areas 172 provided by one or more UV source assemblies can be uniform or have a defined deviation from uniformity. The uniformity or defined deviation from uniformity is considered to extend transversely across the entire surface of the packaging substrate, i.e., within the two dimensions of Figure 1. Thus, a uniform light effect can be provided across the surface of the packaging substrate.

[0065] A defined deviation from uniformity can be provided by generating a first illumination area for a first portion of the packaging substrate and a second illumination area for a second portion of the packaging substrate. Illumination can be switched on in one illumination area and off in the other. For example, the pulse length of UV radiation can be changed in different illumination areas. In addition to this, or instead, the intensity of UV radiation can also be changed in different illumination areas. Therefore, in particular with respect to test sequences that provide local charges on the packaging substrate, i.e., test sequences that provide charges only in specific areas of the packaging substrate, such charges may be locally removed in order to improve the overall uniformity of the charge distribution on the packaging substrate.

[0066] Embodiments of this disclosure enable high-speed alternating VUV radiation, such as alternating and / or pulsed UV, for example, having a wavelength of 170 nm or less, in addition to electron beam scanning. The effect of controlling substrate charge with VUV radiation is a photoeffect. Ions generated by VUV light, along with residual gases, may contribute to charge control with UV radiation. Discharge at VUV can be high-speed. Therefore, UV pulses to discharge one or more portions of a packaging substrate can be performed in a test sequence, for example, at one or more different points in the test sequence.

[0067] Figure 1 shows the controller 180. According to some embodiments which can be combined with other embodiments described herein, the controller can be connected to one or more components of the apparatus 100 for non-contact testing of packaging substrates. As illustrated in Figure 1, the controller can be connected to the power supply 130, the scanning controller 123, the analysis unit 141, the UV source assembly (source and / or shutter), and the stage 150. The controller may further be connected to the electron detector 140.

[0068] The controller 180 includes a central processing unit (CPU), memory, and, for example, support circuits. To facilitate control of the apparatus for testing packaging substrates, the CPU may be one of any form of general-purpose computer processor and subprocessor that can be used in an industrial environment to control various chambers. Memory is coupled to the CPU. The memory or computer-readable medium may be one or more readily available memory devices, such as local or remote random access memory, read-only memory, hard disks, or any other form of digital storage. Support circuits may be coupled to the CPU to support the processor in a conventional manner. These circuits may include caches, power supplies, clock circuits, input / output circuits, and associated subsystems. Generally, the memory stores test process instructions as software routines, which are usually known as recipes. The software routines may be further stored and / or executed by a second CPU (not shown) located far away from the hardware controlled by the CPU. When executed by a CPU, the software routines transform a general-purpose computer into a special-purpose computer (controller) that controls the operation of a device, for example, a device operation to control charge control during a test operation, such as a device operation to control charge control by UV radiation, incident energy, stage positioning, and / or charged particle beam scanning. Although the methods and / or processes of the present disclosure are discussed as being implemented as software routines, some of the method steps disclosed herein may be executed in hardware or by a software controller. Thus, embodiments of the present invention may be implemented in software executed on a computer system, in hardware as an application-specific integrated circuit or other type of hardware embodiment, or as a combination of software and hardware.

[0069] The controller may perform or carry out a method for testing a packaging substrate using an electron beam column. According to some embodiments, the method includes directing an electron beam from at least one electron beam column onto at least a first portion of the packaging substrate with a first incident energy, and directing an electron beam from at least one electron beam column onto the packaging substrate with a second incident energy different from the first incident energy. The method further includes detecting signal electrons emitted at the time of electron beam collision in order to test at least one first inter-device electrical interconnection path of the packaging substrate.

[0070] According to one embodiment, an apparatus is provided for testing a packaging substrate using any of the methods described herein. The apparatus may include a controller 180. The controller includes a processor and memory that store instructions, when executed by the processor, causing the apparatus to perform the methods according to embodiments of the present disclosure.

[0071] Figures 2A and 2B show enlarged cross-sectional views of a packaging substrate during the test method described herein. The packaging substrate 10 may be an AP substrate or a PLP substrate for manufacturing a multi-die integrated package and includes a first die connection interface for mounting a first die 301 and a second die connection interface for mounting a second die 302. Multiple inter-device electrical interconnection paths (four of which are illustrated in Figures 2A and 2B) extend between each first surface contact of the first die connection interface and each second surface contact of the second die interconnection interface. These surface contacts may be formed as solder bumps having three-dimensional geometries, for example, solder bumps having an essentially hemispherical shape, or may include solder bumps having three-dimensional geometries, for example, solder bumps having an essentially hemispherical shape.

[0072] In Figure 2A, a first inter-device electrical interconnection path 20 extending between a first surface contact 21 and a second surface contact 22 is tested by directing a charged electron beam 111 onto a first surface contact 21 and then onto a second surface contact 22. Since the first surface contact 21 is electrically connected to the second surface contact 22 by the first inter-device electrical interconnection path 20, after charging the first surface contact 21, the second surface contact 22 should be at the same potential as the first surface contact 21. Signal electrons 113 emitted from the second surface contact 22 are detected, and these signal electrons 113 contain information about the potential of the second surface contact 22, which should be equal to the potential of the first surface contact 21. A defect is detected if it is determined that the potential of the second surface contact 22 is different from the potential of the first surface contact 21. The detected voltage contrast can be used to characterize the defect. Furthermore, the detected voltage contrasts of subsequent measurements of adjacent electrical interconnection paths can be compared to determine whether there is a short circuit or leakage between different electrical interconnection paths.

[0073] After testing the first inter-device electrical interconnection path 20, the electron beam 111 can be guided to the two surface contacts of the second inter-device electrical interconnection path 23, for example, by scanning the electron beam to other positions using separate scanning deflectors (vector scanning) and / or by moving a stage on which the packaging substrate is supported. Multiple inter-device electrical interconnection paths can be subsequently tested using a charged electron beam and a search electron beam. Thus, multiple test points can be tested sequentially and / or in parallel.

[0074] In Figure 2B, an open circuit 151 exists in the first inter-device electrical interconnection path 20. The reason it is determined to be an open circuit 151 is that the second surface contact 22 is not charged after or during the charging of the first surface contact 21 by the charged electron beam 111.

[0075] In Figure 2B, a short circuit 152 exists between the second inter-device electrical interconnection path 23 and the third inter-device electrical interconnection path 24. The short circuit is determined because the third inter-device electrical interconnection path 24 is charged along with the second inter-device electrical interconnection path 23, which can be detected by a probe electron beam guided onto an additional surface contact 27 of the third inter-device electrical interconnection path 24 after or during the charging of the second inter-device electrical interconnection path 23.

[0076] For evaluation and defect classification, measurement signals and / or previously collected data of adjacent interconnection paths can be compared in a manner that allows for the identification of open circuits, short circuits, and leaks in the packaging substrate.

[0077] Figure 3 is a schematic top view of the packaging substrate 10 described herein during testing. The packaging substrate has a top surface including a plurality of surface contacts arranged in a two-dimensional pattern. The packaging substrate 10 includes a first die connection interface 31 for mounting a first die, in particular by flip-chip mounting; a second die connection interface 32 for mounting a second die, in particular by flip-chip mounting; and optional additional die connection interfaces, which may be arranged in pairs adjacent to each other. The first die connection interface 31 may include a plurality of first surface contacts, for example, formed as solder bumps, and the second die connection interface 32 may include a plurality of second surface contacts, for example, formed as solder bumps.

[0078] In some embodiments, each first surface contact of the first die connection interface 31 is connected to each of one second surface contacts of the second die connection interface 32 by an inter-device electrical interconnection path. For simplicity, only the inter-device electrical interconnection path connecting the first die connection interface and the second die connection interface is shown. According to some embodiments that can be combined with other embodiments described herein, the first surface contacts may be connected to one second surface contact. Alternatively, the first surface contacts may be connected to two or more second surface contacts. These two or more second surface contacts can be explored using an electron beam, for example, after a charge has been applied to the first surface contacts.

[0079] According to the test method described herein, a charged electron beam 111 is directed, particularly focused, over a first surface contact of the first die connection interface 31, and then directed, particularly focused, over the associated second surface contact of the second die connection interface 32. Signal electrons emitted from the second surface contact are detected to test whether an "open circuit" defect exists in the electrical interconnection path connecting the first and second surface contacts. Subsequently, the remaining surface contacts of the first and second die connection interfaces may be tested, particularly in pairs.

[0080] Alternatively, or in addition to, testing can be performed in parallel or subsequently in such a manner that it is possible to determine whether a "short circuit" defect is caused by charging of the surface contacts of one inter-device electrical interconnection path as a result of charging of another inter-device electrical interconnection path. For example, an electron beam can be rasterized over a portion of the packaging substrate to generate an image of that portion of the packaging substrate. The image can then be evaluated, for example, by pattern recognition.

[0081] Figures 4A to 4D show enlarged cross-sectional views of packaging substrates that can be tested according to the methods described herein.

[0082] The packaging substrate 10 shown in Figure 4A has surface contacts on both main surfaces of the packaging substrate. For example, a first set of multiple device electrical interconnection paths may extend between a first surface contact and a second surface contact exposed on the upper surface of the substrate, and a second set of multiple device electrical interconnection paths may extend between a first surface contact and a second surface contact exposed on the lower surface of the substrate.

[0083] The packaging substrate 10 shown in Figure 4B has at least three surface contacts 25, namely a first surface contact, a second surface contact, and at least one inter-device electrical interconnection path extending between at least a third surface contact.

[0084] The packaging substrate 10 shown in Figure 4C has at least one inter-device electrical interconnection path that extends in a complex network of connections between at least three surface contacts 25 exposed on different main surfaces of the substrate. Such an inter-device electrical interconnection path may be configured to connect three or more dies to each other through the packaging substrate.

[0085] The packaging substrate 10 shown in Figure 4D has at least one interconnection bridge 29 embedded in the packaging substrate 10. At least one inter-device electrical interconnection path extends through at least one interconnection bridge 29. In particular, multiple inter-device electrical interconnection paths extend through the interconnection bridge between a first die connection interface and a second die connection interface of the packaging substrate. The interconnection bridge may be embedded in the packaging substrate during the manufacturing of the packaging substrate. The interconnection bridge may also be a bridge chip embedded in the packaging substrate to increase the connection speed between multiple dies.

[0086] According to some embodiments that can be combined with other embodiments described herein, the test methods and / or apparatus of this disclosure may be used during and / or after the manufacture of a packaging substrate. For example, the test may be applied to a packaging substrate that does not yet contain all layers or structures. For example, the test may be performed after the redistribution layer (RDL) has been manufactured and / or after the via layer has been manufactured. RDL testing and / or via testing can be provided. Furthermore, testing may be provided for completed packaging substrates.

[0087] The test may be provided by charging one or more parts, for example, surface contacts (writing to one or more parts), and by detecting the charge on the packaging substrate by signal electrons (reading the charge). The number of electrons emitted from the surface of the packaging substrate per irradiated electron, i.e., the total electron yield, is energy-dependent. For a total electron yield of 1, the same number of electrons reach the surface of the packaging substrate as the number of signal electrons emitted from the surface of the packaging substrate or the number of signal electrons scattered on the surface of the packaging substrate. The total electron yield is equal to 1, i.e., there are two neutral energy values ​​with no charge, i.e., the first neutral energy value E N1 and the second neutral energy value E N2 Such electron beams exist. According to some embodiments that can be combined with other embodiments described herein, an electron beam having one of these neutral energy values ​​can be used to read the surface of a packaging substrate, i.e., to detect signal electrons.

[0088] According to several embodiments that can be combined with other embodiments described herein, directing an electron beam onto a portion of the packaging substrate with a first incident energy can be a charging operation. The charging operation "writes" a charge to one electrical interconnection path or a network of electrical interconnection paths. Furthermore, directing an electron beam onto a portion of the packaging substrate with a second incident energy can be a signal electron detection operation. The electron beam of the second incident energy may "read" a charge to one electrical interconnection path or a network of electrical interconnection paths.

[0089] According to several embodiments that can be combined with other embodiments described herein, charging of a portion of the packaging substrate during signal electron detection, i.e., during charge reading, is reduced or avoided. In particular, while signal electron detection, for example, while detecting a previously provided charge, impact on the charge of an electrical interconnection path or network of electrical interconnection paths is avoided or kept to a minimum.

[0090] For example, suppose a network of electrical interconnection paths contains five (or any number greater than two) surface contacts. A charge can be added to, or "written to," the first surface contact. The charge added to the network of electrical interconnection paths can be "read" at the second surface contact. While "reading" the charges on the second through fifth surface contacts, it is beneficial not to change the charge in the network of electrical interconnection paths with five surface contacts. Therefore, by utilizing the neutral energy value with respect to the incident energy, charge generation can be reduced or avoided while detecting signal electrons.

[0091] The neutral energy value is material-dependent. The material of the packaging substrate or the surface material of the packaging substrate is known, and the incident energy can be adapted to the packaging substrate material in relation to the method for testing the packaging substrate. The first neutral energy value can be several hundred eV. The second neutral energy value can be between 1.5 keV and 2.5 keV for a typical packaging substrate or a typical surface contact on the packaging substrate. According to several embodiments that can be combined with other embodiments described herein, the incident energy of the test method can be selected to be higher than the second neutral energy value for charging, between the first neutral energy value and the second neutral energy value for charging, or lower than the first neutral energy value. The incident energy can be adapted according to the test strategy, the material of the packaging substrate, and / or the material of the surface contact.

[0092] For incident energies lower than the first neutral energy value, negative charging occurs; that is, the total electron yield is less than 1. For incident energies between the first and second neutral energy values, positive charging occurs; that is, the total electron yield is greater than 1. A total electron yield greater than 1 is related to more electrons leaving the surface than the number of electrons that collide with the surface. Therefore, the packaging substrate or structure becomes positively charged. For incident energies higher than the second neutral energy value, negative charging occurs; that is, the total electron yield is less than 1. A total electron yield less than 1 is related to fewer electrons leaving the surface than the number of electrons that collide with the surface. The packaging substrate or structure becomes negatively charged.

[0093] According to embodiments of this disclosure, a test structure, such as a region and / or surface contact of a packaging substrate, can be positively or negatively charged by electron beam collision. The total electron yield can be controlled with respect to the secondary electron yield depending on the primary energy level, i.e., the incident energy. The test point potential can be determined. The voltage contrast principle can be used for defect detection. According to some embodiments that can be combined with other embodiments described herein, the incident energy can be varied to be higher or lower than a second neutral energy value. The incident energy of the electron beam is set to a predetermined incident energy and positioned on a portion of the packaging substrate, for example, on a surface contact or test point on the packaging substrate. The electron beam remains on that portion of the packaging substrate for a specified time in order to positively or negatively charge that portion of the packaging substrate with respect to the environment of that portion of the packaging substrate. For example, the environment of a surface contact during testing can be one or more adjacent surface contacts.

[0094] According to embodiments of the present disclosure, UV radiation is used to discharge the positive or negative charge provided as described above. According to one embodiment, a method for testing a packaging substrate is provided. The packaging substrate is a panel-level packaging substrate or an advanced packaging substrate. As shown in Figure 5, the method is carried out using an electron beam column and includes placing the packaging substrate on a stage in a vacuum chamber (see operation 501). In operation 502, at least one electron beam from at least one electron beam column is directed onto at least a first portion of the packaging substrate, and in operation 503, at least one electron beam from at least one electron beam column is directed onto at least a second portion of the packaging substrate. In operation 504, signal electrons emitted upon collision of at least one electron beam are detected to test a first inter-device electrical interconnection path of the packaging substrate. In operation 505, at least a third portion of the packaging substrate is illuminated with UV radiation. For example, at least the third part may include, or be made to be, at least the same as the first part, and / or may include, or be made to be, at least the same as the second part. When a charge is applied to the first part, it is beneficial for the discharging third part to be the same as the first part. When a charge is applied to the first and second parts (which is the first part), it is beneficial for the discharging third part to be the same as the first and second parts.

[0095] According to several embodiments that can be combined with other embodiments described herein, at least one electron beam can be directed over at least a first portion with a first incident energy and over at least a second portion with a second incident energy different from the first charging incident energy. For example, to read a charge on a packaging substrate, signal electrons can be detected when at least one electron beam collides with the second incident energy. For example, the second incident energy can be the neutral energy value or a value close to the neutral energy value. For example, the reading incident energy deviates from the neutral energy value by less than ±10%, and the neutral energy value corresponds to the incident energy at which the total electron yield is 1.

[0096] According to some embodiments that can be combined with other embodiments described herein, illumination with UV radiation is provided after detection of signal electrons. Thus, a charge can be added during or during a test sequence, and signal electrons can be detected, for example, to read a previously added charge. The charge is then removed by illumination with UV radiation. Thus, another test sequence may then be started, in which case the charge from the previous test sequence or part of the test sequence has been removed. According to some embodiments that can be combined with other embodiments described herein as described above, the method may include a plurality of test sequences, each test sequence including, in this order: (a) directing at least one electron beam from at least one electron beam column onto a packaging substrate with a write incident energy; (b) directing at least one electron beam from at least one electron beam column onto a packaging substrate with a read incident energy; (c) detecting signal electrons emitted upon collision of at least one electron beam with a read incident energy to test a first inter-device electrical interconnection path of the packaging substrate; and (d) illuminating a portion of the packaging substrate with UV radiation.

[0097] Furthermore, embodiments that can be combined with other embodiments described herein may include illuminating at least a fourth portion of the packing substrate with UV radiation, which is provided after the packaging substrate is placed on the stage and before the electron beam is directed onto the packaging substrate. Thus, excess charge can be neutralized. The packaging substrate can be placed under defined charge conditions.

[0098] Embodiments of the present disclosure may include a method for testing a packaging substrate, as shown by the flowchart in Figure 6. In operation 601, an advanced packaging substrate or a panel-level packaging substrate may be loaded into a test chamber, for example, a vacuum chamber 110 shown in Figure 1. In operation 602, the packaging substrate is moved below the electron beam column. In operation 603, the substrate is irradiated with VUV radiation to neutralize excess charge and / or place the substrate under a defined charge condition. Furthermore, a reference potential, for example, a reference to earth, may be provided via a conductive stage as described above. In operation 604, after a VUV pulse having a length of, for example, 100 milliseconds or less, the VUV may be turned off and an electron beam test or test sequence may be started. For example, the dose may be defined by the pulse time. The electron beam test or electron beam test sequence may include charging of test points, i.e., surface contacts on the packaging substrate, and reading of test points, i.e., surface contacts on the packaging substrate. According to several embodiments that can be combined with other embodiments described herein, an intermediate VUV discharge operation can be provided during or during an e-beam test.

[0099] As shown in Figures 7A and 7B, generating specified charge conditions is beneficial in improving test results. Figure 7A shows an image of a portion of the packaging substrate, e.g., a test pad, before UV radiation. Without pre-adjustment by VUV, the image shows reduced uniformity and higher noise. Different e-beam placements on the test pad will result in different signal levels. For different electron beam positions on the test pad, the correlation between the test pad potential and voltage contrast may differ. As shown in Figure 7B, with pre-adjustment by VUV, the image shows improved uniformity and lower signal noise. Different e-beam placements on the test pad will result in the same signal level. A good correlation between the test pad potential and voltage contrast can be provided. Therefore, pre-adjustment by UV radiation can provide improved charge uniformity and improved signal-to-noise ratio. Defect detection capability can be improved, and more precise parameter measurements, i.e., capacity, can be performed. [Industrial applicability]

[0100] Embodiments of this disclosure provide electron beam testing, particularly electron beam testing including electron beam writing of charges onto a packaging substrate and electron beam reading of charges on a packaging substrate. Illumination with UV radiation is used to discharge one or more portions of the packaging substrate, in particular, to generate defined measurement and / or start conditions. Defined conditions for various or all test points, i.e., various or all surface contacts, can provide an improved signal-to-noise ratio. A uniform charge control method can be provided for the entire test area. Charge control is fast, particularly when the photo-effect is faster than other effects. Furthermore, discharge can be provided without stage motion. The discharge speed allows for different test modes using high-speed alternating VUV irradiation and e-beam scanning. Contactless charge control can be provided.

[0101] According to several embodiments that can be combined with other embodiments described herein, at least one electron beam can be focused while directing the electron beam over at least a first portion of the packaging substrate and over at least a second portion of the packaging substrate. In addition, or instead, the electron beam can also be scanned at one or more locations on the packaging substrate for charging and detecting signal electrons.

[0102] Embodiments of this disclosure offer one or more of the following advantages: Non-contact electrical testing of packaging substrates disclosed herein can be provided, in which charge can be controlled for electrical defect detection. Test speed can be increased considering the flexibility of the electron beam. An improved signal-to-noise ratio can be provided by specified conditions for various or all test points, i.e., various or all surface contacts. A uniform charge control method can be provided in the whole of the complete test area. Testing including 100% of the electrical interconnection paths is possible during mass production. Furthermore, the flexibility of the electron beam allows for testing and flexible configuration for different AP / PLP substrate layouts. Furthermore, the test methods and apparatus disclosed herein can be scaled to smaller dimensions, in particular when technological development moves toward smaller structural sizes. Testing of packaging substrates does not cause damage.

[0103] While the above description covers several embodiments, other embodiments and additional embodiments may be devised without departing from the basic scope of the embodiments of this disclosure, and the scope of the embodiments of this disclosure is defined by the following claims.

Claims

1. A method for testing a packaging substrate (10) using at least one electron beam column, wherein the packaging substrate is a panel-level packaging substrate or an advanced packaging substrate, and the method is The packaging substrate (10) is placed on a stage (105) inside a vacuum chamber (101), Guiding at least one electron beam of the at least one electron beam column onto at least a first portion of the packaging substrate, Guiding the at least one electron beam of the at least one electron beam column onto at least a second portion of the packaging substrate, To test the first inter-device electrical interconnection path of the packaging substrate, the signal electrons emitted during the collision of at least one electron beam are detected, Illuminating at least the third portion of the packing substrate with UV radiation Methods that include...

2. The method according to claim 1, wherein the at least one electron beam is guided over at least the first portion with a first incident energy and over at least the second portion with a second incident energy different from the first incident energy.

3. The method according to claim 2, wherein the signal electron is detected when the at least one electron beam collides with the second incident energy in order to read the charge on the packaging substrate.

4. The method according to any one of claims 1 to 3, wherein the illumination with UV radiation is provided after the detection of signal electrons.

5. Further comprising providing multiple test sequences, each test sequence is: (a) Guiding the at least one electron beam of the at least one electron beam column onto the packaging substrate with the writing incident energy, (b) Guiding the at least one electron beam of the at least one electron beam column onto the packaging substrate with a read incident energy, (c) To test the inter-device electrical interconnection paths of the packaging substrate, detect signal electrons emitted at the time of collision of the at least one electron beam having the reading incident energy, and (d) Illuminating the packing substrate with UV radiation. The method according to claim 4, comprising in this order.

6. The method according to claim 5, wherein the read incident energy deviates from the neutral energy value by less than ±10%, and the neutral energy value corresponds to the incident energy at which the total electron yield is 1.

7. The method further includes illuminating at least a fourth portion of the packing substrate with UV radiation, At least the fourth portion is illuminated after the packaging substrate is placed on the stage and before the electron beam is directed onto the packaging substrate. The method according to any one of claims 1 to 6.

8. The method according to any one of claims 1 to 7, wherein the at least one electron beam is focused while the electron beam is directed over at least the first portion of the packaging substrate and over at least the second portion of the packaging substrate.

9. To charge and to detect the signal electrons, the electron beam is scanned at one or more locations on the packaging substrate. The method according to any one of claims 1 to 8, further comprising:

10. While the packaging substrate is illuminated with UV radiation, the shutter is moved to provide one or more UV radiation pulses. The method according to any one of claims 1 to 9, further comprising:

11. The method according to any one of claims 1 to 11, wherein the UV radiation is VUV radiation, and in particular VUV radiation with a wavelength of 170 nm or less.

12. The packaging substrate includes a plurality of inter-device electrical interconnection paths extending between each first surface contact and the second surface contact, and the method is Testing the electrical interconnection paths between the plurality of devices sequentially and / or in parallel. The method according to any one of claims 1 to 11, including the method described above.

13. The method according to claim 12, wherein the first surface contact and the second surface contact have a diameter of 25 μm or less, and more particularly 10 μm or less.

14. The aforementioned signal electrons are passed through an energy filter. The method according to any one of claims 1 to 13, further comprising:

15. Apparatus for testing a packaging substrate according to the method described in any one of claims 1 to 14.

16. An apparatus (100) for non-contact testing of a packaging substrate (10), Vacuum chamber (101), The stage (105) is located within the vacuum chamber, and the stage is configured to support the packaging substrate, which is a panel packaging substrate or an advanced packaging substrate. A charged particle beam column (120) configured to generate an electron beam and The charged particle beam column is equipped with, An objective lens (124) configured to focus the electron beam onto the packaging substrate, A scanner configured to scan the electron beam at different locations on the packaging substrate, An electron detector (140) for detecting signal electrons (113) emitted when the electron beam collides with the packaging substrate, Equipped with, The aforementioned device A UV source assembly configured to illuminate the packaging substrate in the vacuum chamber with one or more UV radiation pulses, Based on the aforementioned signal electrons (113), an analysis unit (141) is used to determine whether the first inter-device electrical interconnection path (20) has a defect. A device (100) further equipped with the following.

17. Furthermore, the UV source assembly, A UV source that emits UV radiation, A movable shutter for generating one or more UV radiation pulses The apparatus according to claim 16, including the apparatus described in claim 16.

18. The aforementioned stage, A conductive stage surface that is directly or indirectly grounded to provide a reference potential. The apparatus according to any one of claims 16 to 17, comprising:

19. The electron detector (140) Energy filter (142) for the signal electron (113) The apparatus according to any one of claims 16 to 18, comprising:

20. A scanning controller (123) is configured to sequentially guide the electron beam to each pair of the first and second surface contacts in order to test the respective inter-device electrical interconnection paths extending between each pair of the first and second surface contacts. The apparatus according to claim 16 or 19, further comprising:

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