METHOD FOR TESTING PACKAGING SUBSTRATES AND APPARATUS FOR TESTING PACKAGING SUBSTRATES - Patent application

Abstract

A method is described for testing a packaging substrate using at least one electron beam column, the packaging substrate being 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 the at least one electron beam column onto at least a first portion of the packaging substrate, directing at least one electron beam of the at least one electron beam column onto at least a second portion of the packaging substrate, detecting signal electrons emitted upon impingement of the at least one electron beam to test a first inter-device electrical interconnect path of the packaging substrate, and illuminating at least a third portion of the packaging substrate with UV radiation.

Description

[Technical field]

[0001] The present disclosure relates to a method and apparatus for testing packaging substrates. More particularly, embodiments described herein relate to contactless testing of electrical interconnects in packaging substrates, i.e., Panel Leveling Packing (PLP) substrates or Advanced Packaging (AP) substrates, by using an electron beam, particularly to identify and characterize defects such as shorts, opens, and / or leaks. [Background technology]

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

[0003] Semiconductor packaging substrates and printed circuit boards for manufacturing complex microelectronic 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 complex microelectronic devices may include multiple interconnect paths for connecting semiconductor chips or other electrical devices mounted on the packaging substrate.

[0004] Various methods are known for testing such components. For example, contact pads of a component under test may be contacted with contact probes to determine whether the component is defective. Due to the miniaturization of components, components and contact pads are becoming smaller and smaller, so that contacting the contact pads with the contact probes may be difficult or may even pose a risk of damaging the device under test during testing.

[0005] Packaging substrates are becoming more complex and design rules (feature sizes) are becoming significantly smaller. In such substrates, surface contacts (for later flip-chip 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 probing for electrical testing cannot meet the requirements of mass production testing due to reduced throughput (increased number of test points) and reduced contact reliability (smaller contact size). Besides the issues of size reduction and potentially damaging contact pads, the topography of the packaging substrate poses challenges for other test methods such as those utilizing capacitive or electric field detectors, since such methods benefit from having small mechanical spacing. Summary of the Invention [Problem to be solved by the invention]

[0006] It would therefore be beneficial to provide a test method and test apparatus suitable for reliably and quickly testing complex microelectronic devices, especially packaging substrates such as AP and PLP substrates.

[0007] In view of the above, a method and an apparatus for testing a packaging substrate are provided according to the independent claims. Further aspects, advantages and beneficial features are evident from the dependent claims, the description and the 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 the at least one electron beam column onto at least a first portion of the packaging substrate, directing at least one electron beam of the at least one electron beam column onto at least a second portion of the packaging substrate, detecting signal electrons emitted upon impingement of the 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, there is provided an apparatus for testing a packaging substrate according to any of the methods described herein.

[0010] According to one embodiment, an apparatus for contactless testing of a packaging substrate is provided, the apparatus comprising: a vacuum chamber; a stage in the vacuum chamber, the stage configured to support a packaging substrate, the packaging substrate being a panel packaging substrate or an advanced packaging substrate; 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 on the packaging substrate, a scanner configured to scan the electron beam to different positions on the packaging substrate, and an electron detector for detecting signal electrons emitted when the electron beam strikes the packaging substrate, the apparatus further comprising: a UV source assembly configured to illuminate the packaging substrate in the vacuum chamber with one or more UV radiation pulses; and an analysis unit for determining whether a first inter-device electrical interconnect path has defects based on the signal electrons.

[0011] The embodiments are also directed to apparatus for carrying out the disclosed methods, including apparatus parts for carrying out each method aspect described. These method aspects may be carried out as hardware components, as a computer programmed by appropriate software, by any combination of the two, or in any other manner. Additionally, embodiments according to the present disclosure are also directed to 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 aspects for performing any function of the apparatus.

[0012] So that the above-listed features of the present disclosure can be understood in detail, a more detailed description of the disclosure briefly outlined above can be had by reference to the embodiments, the accompanying drawings relating to the embodiments of the present disclosure and the description of the accompanying drawings being given below. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic cross-sectional view of an apparatus for testing a packaging substrate according to any of the test methods described herein. [Figure 2A] 1 is an enlarged cross-sectional view of a packaging substrate during any of the testing methods described herein. [Figure 2B] 1 is an enlarged cross-sectional view of a packaging substrate during any of the testing methods described herein. [Diagram 3] FIG. 2 is an enlarged top view of a packaging substrate during any of the testing methods described herein. [Figure 4A] 1 is an enlarged cross-sectional view of a packaging substrate that can be tested according to the methods described herein. [Figure 4B] 1 is an enlarged cross-sectional view of a packaging substrate that can be tested according to the methods described herein. [Figure 4C] 1 is an enlarged cross-sectional view of a packaging substrate that can be tested according to the methods described herein. [Figure 4D] 1 is an enlarged cross-sectional view of a packaging substrate that can be tested according to the methods described herein. [Diagram 5] 4 is a flow diagram of a method for testing a packaging substrate according to embodiments described herein. [Figure 6] 4 is a flow diagram of a method for testing a packaging substrate according to embodiments described herein. [Figure 7A] FIG. 13 shows exemplary images illustrating improvements of embodiments of the present disclosure. [Figure 7B] FIG. 13 shows exemplary images illustrating improvements of embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Reference will now be made in detail to various exemplary embodiments, one or more examples of which are illustrated in the figures. Each example is provided by way of explanation and not by way of limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield additional embodiments. It is intended that the present disclosure include such modifications and variations.

[0015] In the following description of the drawings, the same reference numbers refer to the same components. Only the differences with respect to the individual embodiments are described. The structures shown in the drawings are not necessarily drawn to scale, but rather to aid in a better understanding of the embodiments.

[0016] The embodiments of the present disclosure relate to testing and / or defect review on packaging substrates, i.e., panel leveling packing (PLP) substrates or advanced packaging (AP) substrates, by the methods described herein. At least one electron beam is used to write charge on the packaging substrate and to read charge on the packaging substrate, particularly for the purpose of identifying and characterizing defects such as shorts, opens and / or leaks. According to some embodiments, which may be combined with other embodiments described herein, the voltage contrast on the packaging substrate may be determined by detecting signal electrons. To further improve the voltage contrast in the methods according to the embodiments of the present disclosure and the apparatus according to the embodiments of the present disclosure, charge control is provided. The packaging substrate may be discharged to a defined condition.

[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, which is performed with at least one electron beam column, includes placing the packaging substrate on a stage in 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. Detecting signal electrons emitted upon impingement of the at least one electron beam to test a first inter-device electrical interconnection path of the packaging substrate. Irradiating at least a third portion of the packaging substrate with UV radiation. For example, the at least third portion can include a first portion and a second portion. In particular, the at least third portion can be or can include a packaging substrate. The first portion and the second portion may overlap. However, according to some embodiments, which can be combined with other embodiments described herein, the first portion can be one or more first surface contacts to which an electric charge is written. The second portion may be one or more second surface contacts at which the charge is read.

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

[0019] To reduce the space requirement of semiconductor packages, the complexity of packaging substrates has been increasing over the years. To reduce manufacturing costs, packaging techniques such as 2.5D IC, 3D-IC, and 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 in a single integrated package, where two or more dies are placed on a packaging substrate, such as a silicon interposer or a panel-level packaging substrate. In 2.5D ICs, the dies are placed side-by-side on the packaging substrate, and in 3D ICs, at least some of the dies are placed on top of each other. The assembly can be packaged as a single component, thereby reducing cost and size compared to traditional 2D circuit board assemblies.

[0021] A packaging substrate typically includes a plurality of inter-device electrical interconnect paths for providing electrical connections between chips or dies disposed on the packaging substrate, which 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 end points (referred to herein as surface contacts) exposed on the surface of the packaging substrate.

[0022] An Advanced Packaging (AP) substrate provides inter-device electrical interconnection paths on or within a wafer, e.g., a silicon wafer. For example, an AP substrate may include Through Silicon Via (TSV), which are other conductors that extend through the AP substrate, e.g., through silicon vias (TSV) provided in a silicon interposer. A Panel Level Packaging substrate is provided from a composite material, e.g., from the material of a Printed Circuit Board (PCB), or from another composite material, e.g., including ceramic and glass materials.

[0023] A panel level packaging substrate is manufactured that is 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. Additionally, an AP substrate may be bonded onto the PLP substrate. The panel level substrate typically provides sites for multiple chips, dies, or AP substrates located on its surface, e.g., on one or both sides thereof, and multiple inter-device electrical interconnection paths that extend 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 another shape. In particular, the panel level substrate may have a surface area larger than that of a typical wafer, e.g., 1000 cm. 2 For example, the panel level substrate may have a size of 30cm x 30cm or more, 60cm x 30cm or more, 60cm x 60cm or more.

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

[0026] A "surface contact" may be understood as an end point of an electrical interconnection path exposed on the surface of the packaging substrate in such a manner that an electron beam can be directed onto the surface contact for contactless charging or probing of the electrical interconnection path. The surface contact is configured to make electrical contact with a chip, die, smaller package or other electrical component, such as a capacitor, resistor, coil or the like, that is placed on the surface of the packaging substrate, for example by soldering. The electrical component may further include an active electrical component, such as a transformer that changes the voltage of an area of ​​the package. In some embodiments, the surface contact may be or include a solder bump.

[0027] According to the embodiment of the present disclosure, 100% of the electrical interconnection paths are tested. The cost of ownership of device packages containing chips such as processors, memories or the like (microelectronic devices) is mainly determined by their highly integrated microelectronic devices. Therefore, mounting defect-free microelectronic devices on a defective packaging substrate is disadvantageous in terms of manufacturing costs. It is desirable for the packaging substrate to be completely defect-free before mounting the microelectronic devices.

[0028] The present disclosure relates to a method and apparatus for testing a packaging substrate configured to integrate multiple devices into an integrated package, the packaging substrate including at least one inter-device electrical interconnection path. According to embodiments of the present 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, the test methods and test systems may provide contactless testing. Contact pad pitches below 60 μm or even below about 10 μm are difficult or even impossible for mechanical probing. Moreover, those small contact pads must not be damaged by scratching. Contactless testing is beneficial.

[0029] According to some embodiments, which can be combined with other embodiments described herein, the electron beam column can be operated at a defined incidence energy to provide charge control during charge writing. In particular, the incidence energy, i.e. the energy of the electron beam at the time of impact with the packaging substrate, can be varied to control the charge provided on the packaging substrate. By varying the incidence energy, the impact area of ​​the electron beam can be positively or negatively charged or not charged. Advantageously, no charge is provided to the packaging substrate during the writing operation. The e-beam can be used to provide contactless electrical testing, where a charge can be applied, for example, to a first surface contact, and the charge can be read, for example, to a second surface contact. This allows detection and classification of electrical defects in the packaging substrate. Different e-beam incidence energies (Upe) control the SE yield (secondary electron yield) and therefore the total electron yield. To achieve a voltage contrast signal with good reproducibility on several substrates and / or after repeated e-beam scanning and testing sequences, it is advantageous to discharge the test substrate to a defined condition, for example a starting condition with respect to potential and charge distribution.

[0030] According to some embodiments, which may be combined with other embodiments described herein, a method for testing a packaging substrate includes placing the packaging substrate on a stage in a vacuum chamber, directing an electron beam of at least one electron beam column onto at least a first portion of the packaging substrate with a first incident energy, and directing the electron beam of the 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 upon impingement of the electron beam to test at least a first inter-device electrical interconnect path of the packaging substrate. According to embodiments of the present disclosure, illuminating at least a third portion of the packaging substrate with UV radiation provides a discharge of the at least one portion. A defined potential and / or charge distribution can be provided. This may be repeated one or more times during testing of the packaging substrate. In particular, the UV radiation discharge may be provided multiple times in a test sequence for testing the packaging substrate.

[0031] Testing of features of a packaging substrate, such as testing of electrical interconnect paths of the packaging substrate, can be provided, where charging of the features and / or the packaging substrate can be controlled. pe), i.e. by changing the incident energy of the electron beam incident on the packaging substrate, the charge on the packaging substrate, or on respective portions of the packaging substrate, can be controlled. UV radiation is used to discharge the packaging substrate, i.e. to remove any previously applied charge or charge accumulated on the packaging substrate prior to the test procedure. Thus, an improved contactless electrical test using an electron beam can be provided. The test may include a voltage signal readout, i.e. a voltage contrast measurement upon detection of signal electrons, e.g. secondary electrons. To avoid damage to the surface contacts, the test locations of the advanced packaging substrate or panel level packaging substrate, i.e. the surface contacts, can be charged without contact. The charge can be removed by a photo effect generated by the UV radiation.

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

[0033] As shown diagrammatically in FIG. 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 opposing surfaces. Although the inter-device electrical interconnection path 20 shown in FIG. 1 extends only between a first surface contact 21 and a second surface contact 22, both disposed on a top surface of the packaging substrate, the present disclosure is not limited to only such inter-device electrical interconnection paths, and the inter-device electrical interconnection path may be a complex network of vias, pillars and / or conductors extending through the packaging substrate and having multiple surface contacts.

[0034] The packaging substrate 10 may include a plurality of inter-device electrical interconnect paths 20 for connecting multiple devices disposed on the packaging substrate 10. Although three inter-device electrical interconnect paths are illustratively shown in FIG 1, the packaging substrate 10 may include thousands or tens of thousands of inter-device electrical interconnect paths that are typically electrically isolated from one another as long as no short circuit exists between two electrical interconnect paths.

[0035] According to the embodiment described herein, the packaging substrate 10 is placed on a stage 105 in a vacuum chamber 101. The stage may be movable, in particular movable in a z-direction (i.e., perpendicular to the stage surface) and / or in an x- and y-direction (i.e., in the plane of the stage surface). The stage 105 is provided in the vacuum chamber and configured to support a packaging substrate, which is one of a panel level packaging substrate and an advanced packaging substrate. An electron beam 111 is directed onto the first surface contact 21. An electron beam 112 may be scanned and directed to the second surface contact 22. To test the first inter-device electrical interconnection path 20, signal electrons 113 emitted from the second surface contact 22 are detected. The signal electrons may be secondary electrons and / or backscattered electrons. For example, it may be determined whether the first inter-device electrical interconnection path 20 has an "open circuit" defect.

[0036] Alternatively or in addition, the electron beam 111 is directed onto an additional surface contact 27 that is not an end point of the first inter-device electrical interconnect path 20, i.e., an additional surface contact 27 that belongs to a second inter-device electrical interconnect path 23 that may extend through a packaging substrate adjacent to the first inter-device electrical interconnect path 20. To test the first inter-device electrical interconnect 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 interconnect path 20 has a "short" defect.

[0037] In particular, by detecting the signal electrons 113 emitted when the electron beam 111 strikes the packaging substrate (in particular by determining the energy of the signal electrons 113, which depends on the potential of the second surface contact 22 or the additional surface contact 27), it can be determined whether the first inter-device electrical interconnect path 20 has defects in a "voltage contrast measurement." In particular, defective connections in the packaging substrate can be determined and classified, for example, into open, short and / or leakage defects.

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

[0039] According to the embodiments described herein, both charging and probing are provided using an electron beam, particularly a scanning electron beam. Other test methods, such as electrical and / or mechanical probing, cannot provide the throughput provided by the methods and systems described herein. The methods and systems described herein rely on contactless charging and probing using an electron beam. Furthermore, the contact reliability of electrical and / or mechanical testers decreases with decreasing size of the surface contacts to be tested in the advanced packaging substrate as well as increasing density and number of surface contacts. For example, contact pad sizes below 30 μm are difficult for mechanical probing. Furthermore, for other inspection methods such as capacitive or electric field detectors, the topography of the packaging substrate and the topography of the surface contacts of the packaging substrate may pose problems. Having a charging electron beam is an additional advantage over, for example, flood gun electron charging. Given the complexity of the packing substrate, the capacity of local charging improves the available test procedures compared to charging the entire area using a flood gun. Furthermore, local charging reduces the overall charge that accumulates on the packing substrate. Furthermore, the different charging of different areas may result in a reduction of the overall charge provided on the substrate. For example, the overall charge can be maintained near neutral if one area is positively charged and another area is negatively charged. According to some embodiments, which may be combined with other embodiments described herein, portions of the packaging substrate can be provided with different patterns of charge. According to embodiments of the present disclosure, charge can be removed. For example, the intensity of the UV radiation or the duration of one or more UV radiation pulses can have a locally adapted lateral distribution to provide discharge of localized areas.

[0040] The test method described herein is suitable for testing packaging substrates for multi-device-in-package integration, in particular panel-level packaging substrates (PLP substrates) or advanced packaging substrates (AP substrates), and uses an e-beam to both charge the inter-device electrical interconnection paths 20 and to read the voltage of the charged circuit, in particular by probing the second and / or additional surface contacts. In other words, with the electron beam, both "electric driving" and "probing" are performed in such a way that defects can be found reliably and quickly. Testing by e-beam charging (e.g. with EBT or EBR columns) and e-beam probing is topography independent, fast and flexible with respect to contact location, size and geometry, whereas for other test methods such as capacitive or electric field detectors, the topography of the packaging substrate can be problematic.

[0041] A packaging substrate, such as a PLP substrate, may include multiple inter-device connections, e.g., 5,000 or more, 10,000 or more, 20,000 or more, or even 50,000 or more. The connections may include through silicon vias (TSVs), e.g., through silicon vias (TSVs) provided in a silicon interposer, other conductive lines extending through the packaging substrate, and / or may include multi-die interconnect bridges that may be embedded in the packaging substrate. The packaging substrate may be a multi-layer substrate that includes electrical interconnects in multiple layers, e.g., in a layer stack, disposed on top of each other.

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

[0043] In some embodiments, directing the electron beam 111 onto the first surface contact includes focusing the electron beam 111 onto the first surface contact 21, e.g., focusing the beam probe diameter on the packaging substrate to 30 μm or less, in particular 10 μm or less. Focusing the charged electron beam onto the packaging substrate, e.g., with an objective lens, can prevent charging of substrate surface areas different from the surface contacts and can provide more accurate test results. The electron beam can be scanned across a portion of the packaging substrate to generate an image of the portion of the packaging substrate, in addition to or instead of, and in particular to detect a signal electron beam. The image can include voltage contrast information. For example, pattern recognition within the image can provide defect detection or classification of defects in one or more electrical interconnect paths.

[0044] While conventional PCBs typically include relatively large planar metal pads that form surface contacts for testing, packaging substrates tested according to the embodiments described herein may include a huge number of small convex solder bumps to be tested, 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, in particular 10 μm or less. For example, the first and second surface contacts may be essentially spherical, in particular hemispherical, with a diameter of 25 μm or less, in particular 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, in particular a substantially hemispherical three-dimensional topography.

[0045] In contrast to mechanical testers, the electron beam can be precisely directed onto such small surface areas because it can be focused to a very small probe diameter and can be precisely directed to a given point on the substrate, e.g., with a scanning deflector, e.g., with an accuracy in the sub-μm range. While other testers may slip or slide from a surface contact with a convex geometry, the electron beam can be precisely focused onto any geometry in such a manner that the test methods described herein are geometry and topography independent.

[0046] As shown diagrammatically in Fig. 1, a charged particle beam column 120 may be provided on a first side of the stage 105. In some embodiments, which may 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 optical elements, such as a scanning deflector 122 and / or an objective lens 124, for directing the first electron beam onto a substrate placed on the stage 105. The objective lens 124 may be an electrostatic objective lens (as shown in Fig. 1), a magnetic objective lens or a magnetic-electrostatic objective lens.

[0047] The apparatus 100 further includes an electron detector 140 for detecting the signal electrons 113 emitted when the second electron beam strikes the packaging substrate, and an analysis unit 141 configured to determine whether the first inter-device electrical interconnect path 20 has a defect based on the signal electrons 113. In some embodiments, the analysis unit 141 may be configured to determine whether the electrical interconnect path has a defect, such as a short circuit, an open circuit, and / or a leak, based on the detected signal electrons. Optionally, the analysis unit 141 may be configured to classify the detected defect. In some embodiments, the analysis unit 141 may be configured to determine whether a short circuit or a leak exists between two or more electrical interconnect paths based on the detected signal electrons from the subsequent measurement. In some implementations, the signal electrons 113 detected by the electron detector 140 may provide information about the electrical potential at the substrate location where the signal electrons 113 were emitted or reflected, and the analysis unit 141 may be configured to determine from said information whether the first inter-device electrical interconnect path 20 has a defect. The analysis unit 141 may further be configured to classify the determined defect. In particular, the testing may include determining by the analysis unit 141 whether the first inter-device electrical interconnection path 20 has any of a short circuit, an open circuit, and / or a leak. 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 separated.

[0048] In some embodiments, which may be combined with other embodiments described herein, the electron detector 140 includes an Everhard-Thornley detector. As shown in FIG. 1, an energy filter 142 for the signal electrons 113 may be placed in front of the electron detector 140, and in particular in front of the Everhard-Thornley detector. The energy filter may include a grid electrode configured to be set to a predetermined potential. The energy filter 142 may enable suppression of low energy signal electrons. The energy filter 142 may suppress signal electrons that are not relevant to the voltage contrast measurement being performed. In some implementations, the energy filter 142 may suppress signal electrons emitted from uncharged surface areas and pass only signal electrons emitted from charged surface contacts. The signal current detected by the electron detector may therefore depend on the energy of the signal electrons, which indicates whether the probed surface contact has a defect or not.

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

[0050] For example, the scan controller 123 may be configured to control the scan deflector such that the electron beam is sequentially directed to pairs of first and second surface contacts to test each inter-device electrical interconnect path extending between each pair of first and second surface contacts, allowing for rapid and reliable testing of multiple electrical interconnect paths extending through the packaging substrate.

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

[0052] As shown diagrammatically in FIG. 1, the electron source 121 is connected to a power supply 130. The power supply can provide a high voltage to the electron source for emitting an electron beam, i.e., a primary electron beam, from the electron source. According to some embodiments, which can be combined with other embodiments described herein, the voltage provided by the power supply 130 can be modified to vary the energy of the electron beam and thus the incidence energy of the electron beam incident on the packaging substrate. According to some embodiments, which 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, a power supply can be connected to the electron source (shown in FIG. 1), an extraction electrode of the electron source, an anode of the electron source, a deceleration electrode configured to decelerate the electrons before impacting the packaging substrate, and / or the stage 105. The incidence 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 vary the incidence energy of the electron beam.

[0053] 1, the apparatus 100 can include one or more UV sources 170, such as a UV source that generates UV radiation. The one or more UV sources 170 can be disposed in the vacuum chamber 110. For example, the one or more UV sources 170 can be positioned to enable uniform illumination of a test area of ​​the charged particle beam column 120. An illumination area 172 of the UV source is shown in FIG.

[0054] According to some embodiments, which 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 in the charged particle beam column and / or in 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, in particular immediately before, during or after the electron beam test sequence. In particular, an area 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 stage CV.

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

[0056] According to some embodiments, which may be combined with other embodiments described herein, the wavelength of the UV radiation may be 200 nm or less, in particular 170 nm or less. Additionally or alternatively, a gas discharge tube may be used to generate the radiation. For example, a xenon lamp, a mercury lamp, a deuterium lamp or other similar lamp may be used. The gas discharge lamp may be advantageously operated in a continuous operation mode. According to some embodiments, which may be combined with other embodiments described herein, a shutter configured to provide UV radiation pulses may be advantageous. The UV source 170 and the shutter may be included in a UV source assembly or may form a UV source assembly.

[0057] According to some embodiments, which can be combined with other embodiments described herein, the UV source 170, such as a VUV source, can be replaceable from outside the column or from outside the vacuum chamber. Because UV sources have a limited life span, the maintenance cycle is improved by having one or more UV sources replaceable from outside the vacuum atmosphere. For example, it is conceivable to direct the UV light into the charged particle beam column and / or into the vacuum chamber through a magnesium window.

[0058] According to an embodiment, an apparatus for contactless 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 in the vacuum chamber, the stage configured to support a packaging substrate, the packaging substrate being 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 on the packaging substrate, a scanner configured to scan the electron beam to different positions 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 sources for varying an 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 radiation pulses, and an analysis unit for determining whether the first inter-device electrical interconnect path has defects based on the signal electrons.

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

[0060] 1 illustratively shows a grounded stage 105. The stage may be directly grounded, may be grounded via a DC power supply 106 as illustratively shown in FIG 1, or may be grounded via an AC power supply. According to some embodiments, which may be combined with other embodiments described herein, the stage may include a conductive stage surface that is directly or indirectly grounded to provide a reference potential.

[0061] When the packaging substrate is placed on the stage 105, the packaging substrate has a defined charge provided thereon. Regardless, the stage can be conductive. The stage can therefore be provided at a defined potential. For example, the defined potential can be ground potential, or a negative or positive potential with respect to ground. For example, a DC power source can be provided between the ground and the conductive stage. Alternatively, an AC power source can be provided between the ground and the conductive stage, providing a defined alternating potential. According to some embodiments, which can be combined with other embodiments described herein, the surface of the stage 105 is provided with a non-conductive material. For example, a dielectric material layer can be provided as the surface of the stage. Having a non-conductive stage surface allows for a charge to be applied to and maintained on the packaging substrate for detection during a test operation or a defect review operation.

[0062] The defined potential of the stage, particularly the conductive stage, provides electric field lines, particularly on the stage surface and non-conductive portions of the packaging substrate, that can be used to affect the electron beam of the electron beam column.

[0063] According to additional embodiments, which may be combined with other embodiments described herein, a packaging substrate may be provided in which the capacitive coupling between the packaging substrate and the stage 105 is at a defined potential. For example, a grounded conductive stage 105 may provide the capacitive coupling to earth. Additionally or alternatively, a predetermined set of structures on the packaging substrate may be grounded. However, the predetermined set of structures may not be charged by the ground and may act as a reference potential.

[0064] According to some embodiments, which may be combined with other embodiments described herein, the one or more illumination areas 172 provided by the one or more UV source assemblies may be uniform or may have a prescribed deviation from uniformity. The uniformity or the prescribed deviation from uniformity may be considered to extend laterally across the entire surface of the packaging substrate, i.e., within two dimensions of FIG. 1. Thus, a uniform light effect may be provided across the packaging substrate surface.

[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 illumination area. For example, the pulse length of the UV radiation can be changed in the different illumination areas. Additionally or alternatively, the intensity of the UV radiation can be changed in the different illumination areas. Thus, particularly with regard to test sequences that provide a localized charge on the packaging substrate, i.e., a charge provided only in a specific area of ​​the packaging substrate, such charge may be locally removed in order to improve the overall uniformity of the charge distribution on the packaging substrate.

[0066] In addition to electron beam scanning, embodiments of the present disclosure allow for alternating and / or pulsed UV, e.g., fast alternating VUV radiation, such as those with wavelengths of 170 nm or less. The effect of controlling the substrate charge with VUV radiation is a photo effect. Ions generated by VUV light, along with residual gases, may contribute to charge control with UV radiation. Discharge in VUV can be fast. Thus, UV pulses to discharge one or more portions of the packaging substrate can be performed in a test sequence, e.g., at one or more different points in the test sequence.

[0067] 1 shows a controller 180. According to some embodiments, which may be combined with other embodiments described herein, the controller may be connected to one or more of the components of the apparatus 100 for contactless testing of packaging substrates. As exemplarily shown in FIG. 1, the controller may be connected to the power supply 130, the scan 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 sub-processors that can be used in an industrial environment to control various chambers. The 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 include cache, power supplies, clock circuits, input / output circuits and related subsystems, and the like. The memory typically contains inspection process instructions stored as software routines, which are commonly known as recipes. The software routines may be further stored and / or executed by a second CPU (not shown) located remotely from the hardware controlled by the CPU. The software routines, when executed by the CPU, transform the general-purpose computer into a special-purpose computer (controller) that controls device operations, such as device operations for controlling charge control during a test operation, such as device operations for controlling 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 in the present disclosure may be performed 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 implementation, or as a combination of software and hardware.

[0069] The controller may execute or perform a method of testing a packaging substrate using an electron beam column. According to some embodiments, the method includes directing an electron beam of the at least one electron beam column onto at least a first portion of the packaging substrate at a first incident energy and directing the electron beam of the at least one electron beam column onto the packaging substrate at a second incident energy different from the first incident energy. The method further includes detecting signal electrons emitted upon impingement of the electron beam to test at least one first inter-device electrical interconnect path of the packaging substrate.

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

[0071] 2A and 2B show an enlarged cross-sectional view of a packaging substrate during the testing 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 attaching a first die 301 and a second die connection interface for attaching a second die 302. A plurality of inter-device electrical interconnection paths (four of which are illustratively shown in FIGS. 2A and 2B ) extend between respective first surface contacts of the first die connection interfaces and respective second surface contacts of the second die interconnection interfaces. These surface contacts may be formed as or include solder bumps having a three-dimensional geometry, for example solder bumps having an essentially hemispherical shape.

[0072] In FIG. 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 the first surface contact 21 and directing the electron beam onto the 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. A signal electron 113 emitted from the second surface contact 22 is detected, and the signal electron 113 contains information about the potential of the second surface contact 22, which should be equal to the potential of the first surface contact 21. If it is determined that the potential of the second surface contact 22 is different from the potential of the first surface contact 21, a defect is detected. 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 know if there is a short circuit or leakage between different electrical interconnection paths.

[0073] After testing of the first inter-device electrical interconnect path 20, the electron beam 111 can be directed onto two surface contacts of the second inter-device electrical interconnect path 23, for example, by scanning (vector scanning) the electron beam to other positions using a respective scanning deflector and / or by moving a stage on which the packaging substrate is supported. Using the charging electron beam and the probing electron beam, multiple inter-device electrical interconnect paths can be subsequently tested. Thus, multiple test points can be tested sequentially and / or in parallel.

[0074] 2B, an open 151 exists in the first inter-device electrical interconnect path 20. The open 151 is determined because the second surface contact 22 is not charged after or during the charging of the first surface contact 21 by the charging electron beam 111.

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

[0076] For evaluation and defect classification, measurement signals and / or previously collected data of adjacent interconnect paths can be compared in such a manner that opens, shorts and leaks in the packaging substrate can be identified.

[0077] 3 is a schematic top view of a 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 attaching a first die, particularly by flip-chip attachment, a second die connection interface 32 for attaching a second die, particularly by flip-chip attachment, and optional additional die connection interfaces that may be arranged in pairs next to each other. The first die connection interface 31 may include a plurality of first surface contacts, e.g., a plurality of first surface contacts formed as solder bumps, and the second die connection interface 32 may include a plurality of second surface contacts, e.g., a plurality of second surface contacts formed as solder bumps.

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

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

[0080] Alternatively, or in addition, charging of one inter-device electrical interconnect path may result in charging of the surface contacts of another inter-device electrical interconnect path, either in parallel or in succession, in a manner that may determine a "short" defect. For example, an electron beam may be rastered over a portion of a packaging substrate to generate an image of that portion of the packaging substrate. The image may be evaluated, for example, by pattern recognition.

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

[0082] The packaging substrate 10 shown in Figure 4A has surface contacts on both major surfaces of the packaging substrate. For example, a first plurality of inter-device electrical interconnect paths may extend between first and second surface contacts exposed on the upper surface of the substrate, and a second plurality of inter-device electrical interconnect paths may extend between the first and second surface contacts exposed on the lower surface of the substrate.

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

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

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

[0086] According to some embodiments, which may be combined with other embodiments described herein, the testing method and / or apparatus according to the present disclosure may be utilized during and / or after the manufacturing of a packaging substrate. For example, testing may be applied to a packaging substrate that does not yet include all layers or structures. For example, testing may be performed after a redistribution layer (RDL) is manufactured and / or after a via layer is manufactured. RDL testing and / or via testing may be provided. Additionally, testing may be provided to a completed packaging substrate.

[0087] Testing may be provided by charging one or more portions, e.g., surface contacts (writing to one or more portions) 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 compared to the number of signal electrons emitted from or scattered at the surface of the packaging substrate. There are two neutral energy values ​​for which the total electron yield is equal to 1, i.e., there is no charging, i.e., the first neutral energy value E N1 and the second neutral energy value E N2 According to some embodiments, which 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 some embodiments, which may be combined with other embodiments described herein, directing an electron beam onto a portion of a packaging substrate at a first incident energy may be a charging operation. The charging operation "writes" charge onto an electrical interconnect path or a network of electrical interconnect paths. Additionally, directing an electron beam onto a portion of a packaging substrate at a second incident energy may be an operation of detecting signal electrons. The electron beam at the second incident energy may "read" the charge of an electrical interconnect path or a network of electrical interconnect paths.

[0089] According to some embodiments, which can be combined with other embodiments described herein, charging parts of the packaging substrate during detection of the signal electrons, i.e. during reading of the charge, is reduced or avoided, in particular affecting the charge of the electrical interconnection path or the network of electrical interconnection paths during detection of the signal electrons, e.g. during detection of a previously provided charge, is avoided or kept to a minimum.

[0090] For example, a network of electrical interconnection paths may include five (or any number greater than two) surface contacts. A charge may be applied, or "written," to a first surface contact. At a second surface contact, the charge applied to the network of electrical interconnection paths may be "read." While "reading" the charge on the second through fifth surface contacts, it is beneficial to not change the charge of the network of electrical interconnection paths having five surface contacts. Thus, by utilizing a neutral energy value relative to the incident energy, charge generation may be reduced or avoided while detecting signal electrons.

[0091] The neutral energy value is material dependent. The material of the packaging substrate or the material of the surface of the packaging substrate is known, and the incident energy for the method of testing the packaging substrate can be adapted to the packaging substrate material. 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 a packaging substrate. According to some embodiments, which 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 depending on the test strategy, the material of the packaging substrate and / or the material of the surface contact.

[0092] For incident energies below the first neutral energy value, negative charging occurs, i.e., the total electron yield is less than 1. For incident energies between the first neutral energy value and the second neutral energy value, positive charging occurs, i.e., the total electron yield is greater than 1. A total electron yield greater than 1 is associated with more electrons exiting the surface compared to the number of electrons impinging on the surface. Thus, the packaging substrate or structure is positively charged. For incident energies above the second neutral energy value, negative charging occurs, i.e., the total electron yield is less than 1. A total electron yield less than 1 is associated with fewer electrons exiting the surface compared to the number of electrons impinging on the surface. Thus, the packaging substrate or structure is negatively charged.

[0093] According to embodiments of the present disclosure, test structures, e.g., areas of the packaging substrate and / or surface contacts, can be positively or negatively charged by electron beam impingement. Depending on the primary energy level, i.e., incident energy, the total electron yield can be controlled with respect to the secondary electron yield. The test point potential can be determined. The voltage contrast principle can be utilized for defect detection. According to some embodiments, which can be combined with other embodiments described herein, the incident energy can be varied above a second neutral energy value or below a second neutral energy value. The incident energy of the electron beam is set to a predetermined incident energy and placed on a portion of the packaging substrate, e.g., on a surface contact or a test point on the packaging substrate. The electron beam remains on the portion of the packaging substrate for a defined time to charge the portion of the packaging substrate positively or negatively with respect to the environment of the portion of the packaging substrate. For example, the environment of the surface contact under test can be one or more adjacent surface contacts.

[0094] According to an embodiment of the present disclosure, UV radiation is utilized to discharge the positive or negative charge provided as described above. According to an 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 FIG. 5, the method is performed 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 of the 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 of the 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 impingement of the at least one electron beam are detected to test a first inter-device electrical interconnect path of the packaging substrate. In operation 505, at least a third portion of the packaging substrate is illuminated with UV radiation. For example, the at least third portion can include or be at least the same portion as the first portion and / or can include or be at least the same portion as the second portion. When a charge is applied to the first portion, it is beneficial for the third portion to be the same as the first portion. When a charge is applied to the first portion and the second portion (we are the first portion), it is beneficial for the third portion to be the same as the first portion and the second portion.

[0095] According to some embodiments, which can be combined with other embodiments described herein, at least one electron beam can be directed onto at least a first portion with a first incident energy and onto at least a second portion with a second incident energy different from the first charging incident energy. For example, to read the charge on the packaging substrate, signal electrons can be detected when the at least one electron beam strikes with a second incident energy. For example, the second incident energy can be a neutral energy value or a value close to the neutral energy value. For example, the read incident energy deviates from the neutral energy value by less than +-10%, and the neutral energy value corresponds to an 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 the signal electrons. Thus, charge can be added during a test sequence or during a portion of a test sequence, and the signal electrons can be detected, for example to read the previously added charge. The charge is then removed by illumination with UV radiation. Thus, another test sequence can be subsequently started, with the charge of the previous test sequence or portion of the test sequence being removed. As explained above, according to some embodiments that can be combined with other embodiments described herein, the method may include a plurality of test sequences, each test sequence including, in this order: (a) directing at least one electron beam of at least one electron beam column onto the packaging substrate with a write incident energy; (b) directing at least one electron beam of at least one electron beam column onto the packaging substrate with a read incident energy; (c) detecting the signal electrons emitted upon the impact of the at least one electron beam with the read incident energy to test a first inter-device electrical interconnection path of the packaging substrate; and (d) illuminating a portion of the packing substrate with UV radiation.

[0097] Further, an embodiment that can be combined with other embodiments described herein may include illuminating at least a fourth portion of the packaging substrate with UV radiation, the illumination of the at least fourth portion being provided after placing the packaging substrate on the stage and before directing the electron beam onto the packaging substrate. Thus, excess charge can be neutralized. The packaging substrate can be placed under a defined charge condition.

[0098] An embodiment of the present disclosure may include a method for testing a packaging substrate, as illustrated by the flow diagram shown in FIG. 6. In operation 601, an advanced packaging substrate or a panel level packaging substrate may be loaded into a test chamber, for example, the vacuum chamber 110 shown in FIG. 1. In operation 602, the packaging substrate is moved under an 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. Additionally, a reference potential, for example, a reference to ground, may be provided via the conductive stage 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 begin. For example, a dose may be defined by a pulse time. The electron beam test or test sequence may include charging of test points, i.e., surface contacts on the packaging substrate, and reading of the test points, i.e., surface contacts on the packaging substrate. According to some embodiments, which may be combined with other embodiments described herein, intermediate VUV discharge operation may be provided during e-beam testing or during an e-beam testing sequence.

[0099] As shown in FIG. 7A and FIG. 7B, creating a defined charge condition is beneficial to improve test results. FIG. 7A shows an image of a portion of a packaging substrate, e.g., a portion of a test pad, before UV irradiation. Without VUV preconditioning, the image shows reduced uniformity and higher noise. Different e-beam placements on the test pad will result in different signal levels. For different e-beam positions on the test pad, the correlation between the test pad potential and the voltage contrast may be different. As shown in FIG. 7B, with VUV preconditioning, 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 the voltage contrast can be provided. Thus, UV preconditioning 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] The embodiments of the present disclosure provide for e-beam testing, particularly including e-beam writing of charge onto a packaging substrate and e-beam reading of charge on the packaging substrate. Illumination with UV radiation is utilized to discharge one or more portions of the packaging substrate, particularly to generate defined measurement and / or starting conditions. Improved signal-to-noise ratios can be provided by defined conditions for various or all test points, i.e. various or all surface contacts. A method of integral and uniform charge control of the complete test area can be provided. Charge control is fast, particularly when light effects are faster than other effects. Furthermore, discharge can be provided without stage motion. The speed of discharge allows for different test modes with fast alternating VUV illumination and e-beam scanning. Contactless charge control can be provided.

[0101] According to some embodiments, which may be combined with other embodiments described herein, at least one electron beam can be focused while directing the electron beam onto at least a first portion of the packaging substrate and onto at least a second portion of the packaging substrate. Additionally or alternatively, the electron beam can be scanned to one or more locations on the packaging substrate for charging and detecting signal electrons.

[0102] The embodiments of the present disclosure provide one or more of the following advantages: A contactless electrical test of the packaging substrate disclosed herein can be provided, where 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 defined conditions for various or all test points, i.e. various or all surface contacts. An integrated and uniform charge control method of the complete test area can be provided. Testing involving 100% of the electrical interconnection paths is possible during mass production. Furthermore, the flexibility of the electron beam allows testing and flexible configuration for different AP / PLP board layouts. Furthermore, the test method and apparatus disclosed herein further allows scaling to smaller dimensions, especially as technology development moves to smaller feature sizes. The testing of the packaging substrate does not cause damage.

[0103] The following embodiments also form part of the present disclosure. Embodiment 1. A method for testing a packaging substrate (10) using at least one electron beam column, the packaging substrate being a panel level packaging substrate or an advanced packaging substrate, the method comprising: placing a packaging substrate (10) on a stage (105) in a vacuum chamber (101); directing at least one electron beam of the at least one electron beam column onto at least a first portion of the packaging substrate; directing at least one electron beam of the at least one electron beam column onto at least a second portion of the packaging substrate; Detecting signal electrons emitted upon impingement of the at least one electron beam to test a first inter-device electrical interconnect path of the packaging substrate; illuminating at least a third portion of the packing substrate with UV radiation; A method comprising: Embodiment 2. The method of embodiment 1, wherein at least one electron beam is directed onto at least a first portion with a first incident energy and onto at least a second portion with a second incident energy different from the first incident energy. Embodiment 3. The method of embodiment 2, wherein the signal electrons are detected when at least one electron beam strikes with a second incident energy to read the charge on the packaging substrate. Embodiment 4. The method of any of embodiments 1-3, wherein illumination with UV radiation is provided after detection of the signal electrons. Embodiment 5. The method further includes providing a plurality of test sequences, each test sequence comprising: (a) directing at least one electron beam of at least one electron beam column onto a packaging substrate at a write incident energy; (b) directing at least one electron beam of the at least one electron beam column onto the packaging substrate at a read incident energy; (c) detecting signal electrons emitted upon impact of at least one electron beam having a read incident energy to test inter-device electrical interconnection paths of the packaging substrate; and (d) illuminating a portion of the packaging substrate with UV radiation. 5. The method of embodiment 4, comprising, in that order: Embodiment 6. The method of embodiment 5, wherein the deviation of the read incident energy from the neutral energy value is less than +-10%, and the neutral energy value corresponds to the incident energy that results in a total electron yield of 1. Embodiment 7. The method of any one of embodiments 1 to 6, further comprising illuminating at least a fourth portion of the packaging substrate with UV radiation, wherein illuminating at least the fourth portion is provided after placing the packaging substrate on the stage and before directing the electron beam onto the packaging substrate. Embodiment 8. A method as described in any of embodiments 1 to 7, wherein at least one electron beam is focused while directing the electron beam onto at least a first portion of the packaging substrate and onto at least a second portion of the packaging substrate. Embodiment 9. Scanning an electron beam to one or more locations on a packaging substrate to charge and detect signal electrons. 9. The method according to any one of the preceding embodiments, further comprising: Embodiment 10. Moving a shutter while illuminating a packaging substrate with UV radiation to provide one or more pulses of UV radiation 10. The method of any one of embodiments 1 to 9, further comprising: Embodiment 11. The method according to any one of the preceding embodiments, wherein the UV radiation is VUV radiation, in particular VUV radiation having a wavelength of 170 nm or less. Embodiment 12. A packaging substrate includes a plurality of inter-device electrical interconnect paths extending between respective first and second surface contacts, and a method includes: Sequential and / or parallel testing of multiple inter-device electrical interconnect paths 12. The method according to any one of the preceding claims, comprising: Embodiment 13. The method of embodiment 12, wherein the first surface contact and the second surface contact have a diameter of 25 μm or less, in particular 10 μm or less. Embodiment 14: Passing signal electrons through an energy filter 14. The method of any one of embodiments 1 to 13, further comprising: Embodiment 15. An apparatus for testing a packaging substrate according to the method of any one of embodiments 1 to 14. Embodiment 16. An apparatus (100) for contactless testing of a packaging substrate (10), comprising: A vacuum chamber (101); a stage (105) in a vacuum chamber, the stage configured to support a packaging substrate, the packaging substrate being a panel packaging substrate or an advanced packaging substrate; a charged particle beam column (120) configured to generate an electron beam; The charged particle beam column comprises: an objective lens (124) configured to focus the electron beam onto the packaging substrate; a scanner configured to scan the electron beam to different locations on the packaging substrate; an electron detector (140) for detecting signal electrons (113) emitted when the electron beam strikes the packaging substrate; The apparatus comprises: a UV source assembly configured to illuminate a packaging substrate within the vacuum chamber with one or more pulses of UV radiation; an analysis unit (141) for determining whether the first inter-device electrical interconnect path (20) has a defect based on the signal electrons (113); The apparatus (100) further comprises: Embodiment 17 Further, the UV source assembly comprises: a UV source generating UV radiation; a movable shutter for generating one or more pulses of UV radiation; 17. The device of embodiment 16, comprising: Embodiment 18. The stage is A conductive stage surface that is directly or indirectly grounded to provide a reference potential The device according to any one of embodiments 16 to 17, comprising: Embodiment 19. The electronic detector (140) comprises: Energy filter (142) for signal electrons (113) The device according to any one of embodiments 16 to 18, comprising: Embodiment 20. A scan controller (123) configured to sequentially direct an electron beam to pairs of first and second surface contacts to test each inter-device electrical interconnect path extending between each pair of the first and second surface contacts. 20. The apparatus of any of embodiments 16 or 19, further comprising:

[0104] While the above description is directed to several embodiments, other and additional embodiments may be devised without departing from the basic scope of the disclosed embodiments, the scope of which is determined by the following claims.

Claims

1. A method for testing a packaging substrate (10) for multi-device package integration using at least one electron beam column, comprising: placing the packaging substrate (10) on a stage (105) within a vacuum chamber (101); directing at least one electron beam of the at least one electron beam column onto at least a first portion of the packaging substrate; directing at least one electron beam of the at least one electron beam column onto at least a second portion of the packaging substrate; detecting signal electrons emitted upon collision of the at least one electron beam to test a first inter-device electrical interconnect path of the packaging substrate; illuminating at least a third portion of the packaging substrate with UV radiation; providing a reference potential via a conductive stage while illuminating the third portion with UV radiation A method comprising the above steps.

2. The method according to claim 1, wherein the at least one electron beam is directed onto at least the first portion with a first incident energy and onto 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 electrons are detected when the at least one electron beam collides with the second incident energy to read charges 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 the signal electrons.

5. Further comprising providing a plurality of test sequences, each test sequence comprising: (a) guiding the at least one electron beam of the at least one electron beam column onto the packaging substrate with a 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 reading incident energy; (c) detecting signal electrons emitted upon collision of the at least one electron beam having the reading incident energy in order to test the inter-device electrical interconnection paths of the packaging substrate, and (d) illuminating a portion of the packaging substrate with UV radiation The method according to claim 4, comprising in this order.

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

7. further comprising illuminating at least a fourth portion of the packaging substrate with UV radiation, illuminating at least the fourth portion being provided after placing the packaging substrate on the stage and before guiding the electron beam onto the packaging substrate, The method according to any one of claims 1 to 3.

8. The method according to any one of claims 1 to 3, wherein the at least one electron beam is focused while guiding the electron beam onto at least the first portion of the packaging substrate and onto at least the second portion of the packaging substrate.

9. further comprising scanning the electron beam to one or more positions on the packaging substrate for charging and for detecting the signal electrons The method according to any one of claims 1 to 3.

10. Moving a shutter while illuminating the packaging substrate with UV radiation to provide one or more UV radiation pulses The method according to any one of claims 1 to 3, further comprising this.

11. The method according to any one of claims 1 to 3, wherein the UV radiation is VUV radiation, particularly VUV radiation having a wavelength of 170 nm or less.

12. The packaging substrate includes a plurality of inter-device electrical interconnect paths extending between respective first surface contacts and second surface contacts, and the method includes Sequentially and / or in parallel testing the plurality of inter-device electrical interconnect paths The method according to any one of claims 1 to 3, further comprising this.

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.

14. Passing the signal electrons through an energy filter The method according to any one of claims 1 to 3, further comprising this.

15. An apparatus for testing a packaging substrate according to the method according to any one of claims 1 to 3.

16. An apparatus (100) for non-contact testing of a packaging substrate (10) for multi-device in-package integration, comprising A vacuum chamber (101), and A stage (105) within the vacuum chamber, the stage being configured to support the packaging substrate, the stage (105), and A charged particle beam column (120) configured to generate an electron beam And the charged particle beam column includes An objective lens (124) configured to focus the electron beam onto the packaging substrate, and A scanner configured to scan the electron beam to different positions on the packaging substrate, An electron detector (140) for detecting signal electrons (113) emitted when the electron beam collides with the packaging substrate and the apparatus comprising A UV source assembly configured to illuminate the packaging substrate in the vacuum chamber with one or more UV radiation pulses, An analysis unit (141) for determining whether a first inter-device electrical interconnection path (20) has a defect based on the signal electrons (113) and further comprising an apparatus (100).

17. Further, the UV source assembly comprises A UV source for generating UV radiation, A movable shutter for generating the one or more UV radiation pulses and the apparatus according to claim 16, comprising.

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

19. The electron detector (140) is An energy filter (142) for the signal electrons (113) and the apparatus according to any one of claims 16 to 17, comprising.

20. A scanning controller (123) configured to sequentially direct the electron beam to the pair of the first surface contact and the second surface contact to test each inter-device electrical interconnection path extending between each pair of the first surface contact and the second surface contact and further comprising an apparatus according to any one of claims 16 or 17.

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