Method for testing package substrate and apparatus for testing package substrate

Abstract

A method for testing a package substrate using at least one electron beam column is described. The package substrate is a panel level package substrate or an advanced package substrate. The method comprises the following steps: placing the packaging substrate on a platform in a vacuum chamber; at least a portion of the vacuum chamber is flood with positive ions and / or negative charges; generating an electric field between the one or more electrodes and the package substrate, the electric field configured to accelerate the positive ions or the negative charges toward the substrate; and testing the package substrate in the vacuum chamber using at least one electron beam column.

Description

Technical Field

[0001] The present disclosure relates to a method and apparatus for testing a packaging substrate. More particularly, embodiments described herein relate to contactless testing of electrical interconnects in a packaging substrate (i.e., a panel level packaging (PLP) substrate or an advanced packaging (AP) substrate) by using an electron beam, particularly for identifying, characterizing, detecting and / or classifying defects (e.g., shorts, opens and / or leakages). Background Art

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

[0003] Semiconductor packaging substrates and printed circuit boards used to manufacture complex microelectronic and / or micromechanical components are often tested during and / or after manufacturing to identify defects (e.g., shorts or opens) in metal paths and interconnections provided at the substrate. For example, a substrate used to manufacture a complex microelectronic device may include a plurality of interconnection paths for connecting semiconductor chips or other electrical devices to be mounted on the packaging substrate.

[0004] Various methods for testing such components are known. For example, contact pads of a component to be tested may be contacted with a contact probe to determine whether the component is defective. As components and contact pads become increasingly smaller due to continued miniaturization of components, contacting the contact pads with a contact probe may be difficult and may even risk damaging the device under test during testing.

[0005] The complexity of package substrates is increasing, while design rules (feature size) are decreasing dramatically. Within such substrates, surface contacts (for later flip-chip or other chip mounting) connect to other surface contacts on the package substrate to interconnect semiconductor (or other) devices. Standard methods of electrical testing like electro-mechanical probing cannot meet the requirements of high-volume production test due to reduced throughput (increased number of test points) and reduced contact reliability (smaller contact size). In addition to the issues of reduced size and possible damage to contact pads, the topography of package substrates causes difficulties for other test methods, such as those using capacitive detectors or electric field detectors, because such methods advantageously have small mechanical spacing.

[0006] Therefore, it is beneficial to provide a testing method and a testing apparatus suitable for reliably and quickly testing complex microelectronic devices, especially package substrates, such as AP substrates and PLP substrates. Summary of the invention

[0007] In view of the above, a method and apparatus for testing a package substrate are provided according to the independent claims. Further aspects, advantages and beneficial features are apparent from the dependent claims, the description and the drawings.

[0008] According to one embodiment, a method for testing a package substrate using at least one electron beam column is provided. The package substrate is a panel-level package substrate or an advanced package substrate. The method comprises the following steps: placing the package substrate on a platform in a vacuum chamber; flooding at least a portion of the vacuum chamber with positive ions and / or negative charges; generating an electric field between one or more electrodes and the package substrate, the electric field being configured to accelerate the positive ions or negative charges toward the substrate; and testing the package substrate using at least one electron beam column in the vacuum chamber.

[0009] According to one embodiment, an apparatus for testing a package substrate according to a method according to any embodiment described herein is provided. For example, a controller runs / executes a method for testing a package substrate using an electron beam column according to an embodiment of the present disclosure.

[0010] According to one embodiment, a device for contactless testing of a packaging substrate is provided. The device includes: a vacuum chamber; a platform located in the vacuum chamber, the platform being configured to support the packaging substrate, the packaging substrate being a panel packaging substrate or an advanced packaging substrate; and a charged particle beam column configured to generate an electron beam. The charged particle beam column includes: an objective lens configured to focus the electron beam on the packaging substrate; a scanner configured to scan the electron beam at different positions on the packaging substrate; and an electron detector for detecting signal electrons emitted when the electron beam hits the packaging substrate. The device further includes: one or more electrodes configured to generate an electric field between the one or more electrodes and the packaging substrate, the electric field being configured to accelerate positive ions or negative charges toward the substrate; and an analysis unit for determining whether a first device-to-device electrical interconnect path is defective based on the signal electrons.

[0011] Embodiments also relate to devices for implementing the disclosed methods, and include device components for performing each described method aspect. These method aspects can be performed by hardware components, computers programmed by appropriate software, any combination of the two, or in any other manner. In addition, embodiments according to the present disclosure also relate to methods for operating the described devices and methods for manufacturing the devices and apparatus described herein. The methods for operating the described devices include method aspects for implementing each function of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to be able to understand the above-mentioned features of the present disclosure in detail, a more detailed description of the present disclosure briefly summarized above can be obtained by referring to the embodiments. The accompanying drawings are related to the embodiments of the present disclosure and are described as follows:

[0013] Figure 1A shows a schematic diagram of an apparatus for illustrating charge control according to an embodiment of the present disclosure;

[0014] Figure 1B shows a schematic cross-sectional view of an apparatus for testing a package substrate according to any of the testing methods described herein;

[0015] Figure 2A and Figure 2B showing an enlarged cross-sectional view of a package substrate during any of the testing methods described herein;

[0016] Figure 3 showing an enlarged top view of a package substrate during any of the testing methods described herein;

[0017] Figure 4A-4D shows an enlarged cross-sectional view of a package substrate that may be tested according to the methods described herein;

[0018] Figure 5 and Figure 6 A flowchart showing a method of testing a package substrate according to an embodiment described herein; and

[0019] Fig. 7A , Figure 7B and Figure 7C Exemplary images illustrating improvements of embodiments of the present disclosure are shown. DETAILED DESCRIPTION

[0020] Reference will now be made in detail to various exemplary embodiments, one or more examples of which are illustrated in each of the accompanying drawings. Each example is provided by way of explanation and is not meant to be limiting. For example, features illustrated or described as part of one embodiment may be used on or with other embodiments to produce further embodiments. The present disclosure is intended to include such modifications and variations.

[0021] In the following description of the figures, the same reference numerals refer to the same components. Only the differences related to the various embodiments are described. The structures shown in the figures are not necessarily depicted according to the true scale, but are used to better understand the embodiments.

[0022] 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) according to the methods described herein. At least one electron beam is used to write and read charge on the packaging substrate, in particular for identifying and characterizing defects (such as short circuits, open circuits and / or leakage). A non-contact electrical test using an electron beam can be provided, wherein a voltage signal reading (e.g., a voltage contrast provided by signal electronic sensing) is provided. According to some embodiments that can be combined with other embodiments described herein, the voltage contrast on the packaging substrate can be determined by detecting signal electrons. According to some embodiments that can be combined with other embodiments described herein, the signal electrons can be, in particular, secondary electrons. Further, the test points or contact points can be non-contact charged on the AP or PLP substrate. Non-contact testing avoids or reduces damage to the AP / PLP substrate. Detection and classification of electrical defects are achieved. In order to further improve the voltage contrast in the method according to the embodiments of the present disclosure and the device according to the embodiments of the present disclosure, charge control is provided. The packaging substrate can be discharged or charged to a specified condition. By discharging the test substrate to a specified starting condition with respect to potential and charge distribution, a repeatable voltage contrast signal can be provided by SE (signal electronics) and the defect detection success rate (S / N ratio, signal-to-noise ratio) on several substrates and after repeated electron beam scanning and test sequences can be improved. According to an embodiment of the present disclosure, an ion source is utilized to control the charge condition of an AP or PLP substrate. A specified directional electric field is provided. The electric field separates positive ions from negative ions and guides the positive ions toward the substrate. According to some embodiments that may be combined with other embodiments described herein, the ion source and the electric field electrodes may be integrated in a vacuum test chamber. Any residual negative charge on the positive ion substrate is removed, which is beneficial to the signal-to-noise ratio of the following electron beam test. In addition, the positive ions can provide a positive potential bias to the test substrate, which may be beneficial to the following electron beam test.

[0023] According to one embodiment, a method for testing a package substrate using at least one electron beam column is provided. The package substrate is a panel-level package substrate or an advanced package substrate. The method comprises the following steps: placing the package substrate on a platform in a vacuum chamber; filling at least a portion of the vacuum chamber with positive ions; generating an electric field between one or more electrodes and the package substrate, the electric field being configured to accelerate the positive ions toward the substrate; and testing the package substrate in the vacuum chamber.

[0024] Figure 1AA schematic diagram of a device illustrating the charge control concept is shown. The package substrate 10 is supported on a platform 105. The package substrate is supported in a vacuum chamber 110. According to some embodiments, which can be combined with other embodiments described herein, one or more ion sources are located within the vacuum chamber 110 or at least partially within the vacuum chamber. Figure 1A An ion source 152 is shown. The ion source 152 generates positive ions and negative charges. The vacuum chamber or at least a portion thereof is filled with positive ions and negative charges. According to an embodiment of the present disclosure, the negative charges can be electrons or negative ions. The following describes accelerating the positive ions toward the substrate. However, by changing Figure 1A The potential of the components shown can also accelerate negative ions or electrons toward the substrate.

[0025] Electrode 154 generates electric field 155. Figure 1A As shown, the electric field 155 accelerates positive ions toward the package substrate 10. Therefore, a positive charge is provided on the package substrate 10. For the electrode 154 at a negative potential relative to the substrate, negative ions or electrons are accelerated toward the package substrate. Therefore, a negative charge can be provided on the package substrate.

[0026] According to some embodiments that can be combined with other embodiments described herein, the ion source 152 can be selected from an ion source with a gas supply, an ultraviolet source (such as a VUV source), a spark generating unit, or another ion generating unit. For example, a VUV source generating ions can ionize residual gas in the vacuum chamber, wherein, for example, the ion density can be controlled by the base pressure and the free path of the general trajectory of the ions. According to some embodiments that can be combined with other embodiments described herein, the step of filling the vacuum chamber with positive ions and / or negative charges is provided by an ion source at least partially mounted in the vacuum chamber.

[0027] like Figure 1B As shown, ions are released from the ion source 152 and distributed in the vacuum chamber 110. In particular, the ions can be distributed between the platform 105 and the electrode 154. The electric field 155 separates the positive ions and the negative ions or electrons, respectively. According to some embodiments that can be combined with other embodiments described herein, the package substrate 10 can be placed on the platform 105 at a ground potential and the positively charged electrode 154. The voltage between the electrode 154 and the platform can be provided by the power supply 106. Figure 1B As shown, the electrode 154 can be a separate component installed in the test equipment, or it can be installed in the test equipment. Figure 1B Shown integrated into a charged particle beam column.

[0028] According to the embodiments described primarily in the present disclosure, positive ions are forced toward the substrate, while negative ions or electrons are accelerated toward the positively charged electrode 154. A self-adjusting process is provided that results in a uniform charge distribution. For example, if a first region of the encapsulation substrate 10 is more positively charged than a second region of the encapsulation substrate 10, the first region will experience a smaller electric field and, therefore, less positive charge during subsequent charge control operations. When the ions compensate for the electric field applied by the electrode in any region of the substrate within the homogenous electric field, the deposition of the ions on the substrate will cease.

[0029] Therefore, by controlling the strength of the electric field, the substrate can be charged to a specified potential. For example, the electrode 154 charged to +100 V will generate a zero electric field after the charge is accumulated on the substrate 10, so that the substrate is also biased to +100 V. Therefore, the substrate potential can be adjusted to a predetermined value.

[0030] According to some embodiments that can be combined with other embodiments described herein, before testing the packaging substrate, the residual positive or negative charge on or in the loaded packaging substrate can be neutralized by negative charge or positive ions, for example, by utilizing a charged particle beam column that directs an electron beam to portions of the packaging substrate. Still further, the test substrate can be optionally charged to a more positive potential or a more negative potential. In particular, according to embodiments that can be combined with other embodiments described herein, the substrate is charged to a specified potential, such as a specified potential relative to ground. For subsequent electron beam testing, a higher voltage contrast can be advantageously provided between the positive substrate and the negatively charged test structure on the sample.

[0031] According to an embodiment of the present disclosure, the embodiment of the present disclosure sets the package substrate to a prescribed and, for example, uniform starting condition (charge distribution) to obtain better defect detectability and repeatability. Therefore, due to the prescribed starting conditions, especially the prescribed starting conditions of all test points, a better signal-to-noise ratio can be provided for e-beam measurement.

[0032] If Figure 1B and Figure 5 and Figure 6 In the description, a method for testing a package substrate is provided. The package substrate is a panel-level package substrate or an advanced package substrate. The method performed using at least one electron beam column includes placing the package substrate on a platform in a vacuum chamber.

[0033] According to some embodiments, which can be combined with other embodiments described herein, at least one electron beam is directed onto the at least first portion at a first landing energy and onto the at least second portion at a second landing energy different from the first charging landing 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 package substrate. Charge control is provided by generating positive ions or negative charges before testing, between test sequences, and / or after testing to, for example, neutralize negative charges on the package substrate.

[0034] Over the years, the complexity of packaging substrates has been increasing in order to reduce the space requirements of semiconductor packaging. In order to reduce manufacturing costs, some packaging technologies have been proposed, such as 2.5D IC, 3D-IC and wafer-level packaging (WLP), such as fan-out WLP. In WLP technology, integrated circuits are packaged before being cut. As used herein, "packaging substrate" refers to a packaging substrate configured for advanced packaging technology, particularly WLP technology or panel-level packaging (PLP) technology.

[0035] "2.5D integrated circuits" (2.5D ICs) and "3D integrated circuits" (3D ICs) combine multiple dies in a single integrated package. Here, 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, while in 3D ICs, at least some of the dies are stacked on top of other dies. The assembly can be packaged as a single part, which can reduce cost and size compared to traditional 2D circuit board assemblies.

[0036] The package substrate typically includes a plurality of device-to-device electrical interconnect paths for providing electrical connections between chips or dies to be placed on the package substrate. The device-to-device electrical interconnect paths may extend vertically (perpendicular to the surface of the package substrate) and / or horizontally (parallel to the surface of the package substrate) through the body of the package substrate in the form of a complex network of connections, with their endpoints (referred to herein as surface contacts) exposed at the surface of the package substrate.

[0037] Advanced packaging (AP) substrates provide electrical interconnection paths between devices on or within a wafer such as a silicon wafer. For example, an AP substrate may include through silicon vias (TSVs) (which are provided in a silicon interposer, for example), other conductor lines extending through the AP substrate. Panel-level packaging substrates are provided by composite materials, such as printed circuit board (PCB) materials or other composite materials, including, for example, ceramic and glass materials.

[0038] The manufactured panel-level packaging substrate is configured to integrate multiple devices (e.g., chips / die that may be heterogeneous (e.g., may have different sizes and configurations)) in a single integrated package. Further, AP substrates can be combined on a PLP substrate. The panel-level substrate typically provides sites for multiple chips, dies, or AP substrates placed on its surface (e.g., on one or both sides thereof), as well as multiple inter-device electrical interconnection paths extending through the body of the PLP substrate.

[0039] It is worth noting that the size of the panel-level substrate is not limited to the size of the wafer. For example, the panel-level substrate can be rectangular or have another shape. Specifically, the panel-level substrate can provide a larger surface area than the surface area of ​​a typical wafer, for example, 1000 cm² or more. For example, the size of the panel-level substrate can be 30 cm x 30 cm or more, 60 cm x 30 cm or more, 60 cm x 60 cm or more.

[0040] According to embodiments of the present disclosure, electron beam testing and / or electron beam inspection provides testing of contact pads of 60 microns or less, even about 10 microns or less. Voltage contrast test imaging can be provided. Testing can be provided at or between "surface contacts" of a package substrate.

[0041] "Surface contacts" may be understood as endpoints of electrical interconnect paths that are exposed at the surface of a package substrate so that an electron beam can be directed onto the surface contacts to contactlessly charge or probe the electrical interconnect paths. The surface contacts are configured to make electrical contact with a chip, die, smaller package, or other electrical component (such as a capacitor, resistor, coil, or similar component) to be placed on the surface of the package substrate (e.g., via soldering). Electrical components may also include active electrical components, such as a transformer that changes the voltage in a certain area of ​​the package. In some embodiments, the surface contacts may be or may include solder bumps.

[0042] According to an embodiment of the present disclosure, 100% of the electrical interconnection paths are tested. The cost of ownership of a device package including a chip, such as a processor, a memory or a similar device (microelectronic device) is mainly determined by the highly integrated microelectronic device. Therefore, it is very disadvantageous in terms of manufacturing cost to install a defect-free microelectronic device on a defective packaging substrate. Before installing the microelectronic device, it is best to have a completely defect-free packaging substrate.

[0043] The present disclosure relates to methods and devices for testing package substrates, which are configured to integrate multiple devices in an integrated package and include at least one electrical interconnection path between devices. According to an embodiment of the present disclosure, a test system, a test device or a test method can detect and / or classify defective electrical connections in a package substrate, such as open circuits, short circuits, leakage defects or other. In particular, these test methods and test systems can provide contactless testing. Contact pad spacing of 60 microns or less, even about 10 microns or less, is difficult or even impossible for mechanical detection. Moreover, small contact pads must not be damaged by any scratches. Contactless testing is beneficial.

[0044] According to some embodiments that can be combined with other embodiments described herein, during the writing of the charge, further charge control can be provided by operating the electron beam column at a specified landing energy. In particular, the landing energy (i.e., the energy of the electron beam when it strikes the packaging substrate) can be varied to control the charge provided on the packaging substrate. By varying the landing energy, the impact area of ​​the electron beam can be positively charged, negatively charged, or uncharged. During the writing operation, no charge is advantageously provided to the packaging substrate. A contactless electrical test can be provided with an electron beam, wherein the charge can be located, for example, at a first surface contact, and the charge can be read, for example, at a second surface contact. This enables the detection and classification of electrical defects of the packaging substrate. Different electron beam landing energies (Upe) control the SE yield (secondary electron yield), thereby controlling the total electron yield. In order to obtain a voltage contrast signal with good repeatability on several substrates and / or after repeated electron beam scanning and test sequences, it is beneficial to discharge the test substrate to a specified condition (e.g., a starting condition with respect to potential and charge distribution).

[0045] According to some embodiments that can be combined with other embodiments described herein, a method for testing a package includes the steps of placing a package substrate on a platform in a vacuum chamber, directing an electron beam of at least one electron beam column onto at least a first portion of the package substrate at a first landing energy, and directing an electron beam of the at least one electron beam column onto the package substrate at a second landing energy different from the first landing energy. The method further includes the steps of detecting signal electrons emitted upon impact of the electron beam to test at least a first device-to-device electrical interconnection path of the package substrate.

[0046] Testing of features of a packaging substrate (e.g., electrical interconnect paths) can be provided where charging of the features and / or the packaging substrate can be controlled. Variation of the electron beam primary energy (Upe) (i.e., the landing energy of the electron beam on the packaging substrate) can be used to control the charge on the packaging substrate or a corresponding portion thereof. The test can include a voltage signal read, i.e., a voltage contrast measurement when detecting signal electrons (e.g., secondary electrons). Test locations (i.e., surface contacts) of an advanced packaging substrate or a panel-level packaging substrate can be charged without contact to avoid damage to the surface contacts.

[0047] Figure 1B An apparatus 100 for testing a package substrate 10 according to embodiments described herein is shown in a schematic cross-sectional view. The apparatus 100 comprises a vacuum chamber 101, which may be a test chamber specifically configured for testing, or may be a vacuum chamber of a larger vacuum system, such as a processing chamber of a package substrate manufacturing or processing system.

[0048] like Figure 1B , the package 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 package substrate 10. Optionally, the first inter-device electrical interconnection path 20 may extend between three or more surface contacts, which may be disposed on the same surface or two opposite surfaces of the package substrate. Figure 1B The inter-device electrical interconnection path 20 shown extends only between a first surface contact 21 and a second surface contact 22 both of which are arranged at the top surface of the packaging substrate, but the present disclosure is not limited to such an inter-device electrical interconnection path, and the inter-device electrical interconnection path can be a complex network of vias, pillars and / or wires extending through the packaging substrate and having multiple surface contacts.

[0049] The package substrate 10 may include a plurality of inter-device electrical interconnection paths 20 for connecting a plurality of devices to be placed on the package substrate 10. Figure 1B In the embodiment, three inter-device electrical interconnection paths are described by way of example, but the package substrate 10 may include thousands or tens of thousands of such inter-device electrical interconnection paths. If there is no short circuit between two electrical interconnection paths, these paths are usually electrically isolated from each other.

[0050] According to the embodiments described herein, the packaging substrate 10 is placed on a platform 105 in a vacuum chamber 101. The platform may be movable, in particular in the z direction (i.e., in a direction perpendicular to the platform surface) and / or in the x and y directions (i.e., in the plane of the platform surface). The platform 105 is provided in the vacuum chamber and is 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. The electron beam may be scanned to be directed toward the second surface contact 22. The signal electrons 113 emitted from the second surface contact 22 are detected to test the first device-to-device electrical interconnection path 20. The signal electrons may be secondary electrons and / or backscattered electrons. For example, it may be determined whether the first device-to-device electrical interconnection path 20 has an "open circuit" defect.

[0051] Alternatively or additionally, the electron beam 111 is directed to another surface contact 27 that is not an end point of the first inter-device electrical interconnection path 20, that is, it belongs to the second inter-device electrical interconnection path 23 that can extend through the packaging substrate adjacent to the first inter-device electrical interconnection path 20. The signal electrons emitted from the other surface contact 27 are detected to test the first inter-device electrical interconnection path 20. The signal electrons can 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.

[0052] In particular, by detecting the signal electrons 113 emitted when the electron beam 111 strikes the package substrate (particularly by determining the energy of the signal electrons 113 depending on the potential of the second surface contact 22 or the other surface contact 27), it can be determined in the "voltage contrast measurement" whether the first inter-device electrical interconnection path 20 is defective. Specifically, defective connections in the package substrate can be determined and classified, for example, into open circuits, short circuits and / or leakage defects.

[0053] In some embodiments that may be combined with other embodiments described herein, one or more electrical connections extending between surface contacts on different sides of a substrate are tested. In further embodiments, a first plurality of electrical connections extending between surface contacts on a first side of a substrate, a second plurality of electrical connections extending between surface contacts on a second side of a substrate, and / or a third plurality of electrical connections extending between surface contacts on different sides of a substrate are tested. For example, one or more electron beam columns may be arranged on both sides of a substrate (not shown) so that surface contacts on both sides of the substrate may be charged and / or discharged to test and test the corresponding electrical connections.

[0054] According to the embodiments described herein, charging and detection are provided by an electron beam (particularly a scanning electron beam). Other test methods (such as electrical and / or mechanical detection) cannot provide the throughput provided by the methods and systems described herein. The methods and systems described herein rely on contactless charging and detection with an electron beam. Further, the contact reliability of electrical and / or mechanical testers decreases as the size, density and number of surface contacts to be tested in advanced packaging substrates increase. For example, contact pad sizes of 30 microns or less are difficult to perform mechanical detection. Further, the topography of packaging substrates and packaging substrate surface contacts may cause problems for other test methods (such as capacitive detectors or electric field detectors). For example, compared with the electron charging of a flood gun, it is more advantageous to have a charged electron beam. In view of the complexity of the packaging substrate, the ability to locally charge improves the available test procedures compared to charging the entire area with a flood gun. Further, local charging reduces the overall charge accumulated on the packaging substrate. Further, performing different charging in different areas can result in a reduction in the overall charge provided on the substrate. For example, if one region is positively charged and another region is negatively charged, the overall charge can remain close to neutral.According to some embodiments, which can be combined with other embodiments described herein, a pattern of different charges can be provided on portions of the packaging substrate.

[0055] The test method described herein is applicable to testing a package substrate for integration within a package of multiple devices, in particular, for testing a panel-level package substrate (PLP substrate) or an advanced package substrate (AP substrate), and uses an electron beam for both charging the electrical interconnection path 20 between devices and for reading the voltage of the charged circuit system (in particular, by probing the second surface contact and / or other surface contacts). In other words, both "electrical driving" and "probing" are accomplished with an electron beam, so that defects can be found reliably and quickly. Testing by electron beam charging and electron beam probing (for example, using an EBT column or an EBR column) is not affected by morphology, is fast, and has flexible contact point location, size, and geometry, while for other test methods (such as capacitive or electric field detectors), the morphology of the package substrate may be a problem.

[0056] A packaging substrate, such as a PLP substrate, may include multiple inter-device connections, such as 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) (which are provided, for example, in a silicon interposer), other conductor 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 that are arranged in a stacked arrangement (e.g., arranged in a layer stack) relative to each other.

[0057] In some embodiments, the package substrate 10 includes a plurality of inter-device electrical interconnection paths between corresponding first and second surface contacts, and optional other contacts, and the method may include the following steps: testing the plurality of inter-device electrical interconnection paths sequentially or in parallel. "Sequential testing" as used herein refers to subsequent testing of a plurality of inter-device electrical interconnection paths of a package substrate. For example, 5,000 or more inter-device electrical interconnection paths are tested one after another. "Parallel testing" as used herein may refer to synchronous testing of two or more inter-device electrical interconnection paths. "Parallel testing" as used herein may also refer to testing several inter-device electrical interconnection paths by scanning an electron beam for charging on several first surface contacts within a field of view, while scanning an electron beam for detection on several corresponding second surface contacts within a field of view.

[0058] 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, for example, with a beam probe diameter of 30 microns or less, particularly 10 microns or less, on the packaging substrate. Focusing the charged electron beam onto the packaging substrate (e.g., with an objective lens) can prevent charging of substrate surface areas other than the surface contacts and can provide more accurate test results. Additionally or alternatively, particularly for detection of a signal electron beam, the electron beam can scan a portion of the packaging substrate to generate an image of a portion of the packaging substrate. The image can include voltage contrast information. For example, defect detection or classification of defects in one or more electrical interconnect paths can be provided by performing pattern recognition within the image.

[0059] While conventional printed circuit boards typically include relatively large flat metal pads forming surface contacts for testing, the package substrates tested according to the embodiments described herein may include a large number of small, convex solder bumps to be tested, which makes testing more challenging. In particular, the maximum dimensions of the first surface contact 21 and the second surface contact 22 may be 25 microns or less, in particular 10 microns or less, respectively. For example, the first surface contact and the second surface contact may be substantially circular, in particular hemispherical, with a diameter of 25 microns or less, in particular 10 microns or less. According to some embodiments that may be combined with other embodiments described herein, the surface contacts may have a three-dimensional morphology, in particular a substantially hemispherical shape.

[0060] Compared to mechanical testers, electron beams can be accurately directed onto such small surface areas because the electron beam can be focused to a very small probe diameter and can be accurately directed to a predetermined point on the substrate, such as with a scanning deflector, with an accuracy in the sub-micrometer range. While other testers may slip or slide off of surface contacts with convex geometries, the electron beam can be accurately focused onto arbitrary geometries, making the test method described herein geometry-independent and topography-independent.

[0061] like Figure 1B , the charged particle beam column 120 can be disposed on a first side of the platform 105. In some embodiments that can be combined with other embodiments described herein, the charged particle beam column 120 can have an electron source 121 for generating an electron beam and a beam optical element, such as a scanning deflector 122 and / or an objective lens 124, for directing the first electron beam to a substrate placed on the platform 105. The objective lens 124 can be an electrostatic objective lens (e.g., Figure 1B as shown), magnetic objective lens or magnetic-electrostatic objective lens.

[0062] The device 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 device-to-device electrical interconnection path 20 is defective based on the signal electrons 113. In some embodiments, the analysis unit 141 can be configured to determine whether the electrical interconnection path is defective, such as a short circuit, an open circuit, and / or leakage based on the detected signal electrons. Optionally, the analysis unit 141 can be configured to classify any detected defects. In some embodiments, the analysis unit 141 can be configured to determine whether there is a short circuit or leakage between two or more electrical interconnection paths based on the signal electrons detected from subsequent measurements. In some embodiments, the signal electrons 113 detected by the electron detector 140 can provide information about the potential of the substrate position where the signal electrons 113 are emitted or reflected, and the analysis unit 141 can be configured to determine whether the first device-to-device electrical interconnection path 20 is defective based on the information. The analysis unit 141 can be further configured to classify the determined defects. Specifically, the test may include determining by the analysis unit 141 whether the first inter-device electrical interconnection path 20 has any of short circuit, open circuit and / or leakage. "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. "Short circuit" is understood as an electrical connection between two electrical interconnection paths that are actually to be electrically isolated.

[0063] like Figure 1BAs shown, the charged particle beam column 120 includes a first plurality of electrodes 146 and a second plurality of electrodes 148. The first plurality of electrodes 146 can generate a multipolar field, such as an octopole field, to guide the signal electrons 113 toward the electron detector 140. For example, the first plurality of electrodes can include eight or more electrodes for generating an octopole field. In particular, the multipolar field generated by the first plurality of electrodes 146 can be dynamically adjusted to the position of the electron beam 111 on the packaging substrate 10. The second plurality of electrodes 148 can generate a multipolar field, such as an octopole field, to guide the signal electrons 113 toward the electron detector 140. For example, the second plurality of electrodes can include eight or more electrodes for generating an octopole field. In particular, the multipolar field generated by the second plurality of electrodes 146 can be static. According to some embodiments that can be combined with other embodiments described herein, one or more electrodes in the charged particle beam column 120 can be at least one component of four or eight electrodes (or more electrodes) configured to generate a multipolar field to guide the signal electrons.

[0064] Figure 1B Further shown are an ion source 152 and a gap 153. The ion source 152 generates, for example, positive ions, such as Figure 1A The gap 153 enables the positive ions to be distributed above the packaging substrate 10. During the charge control operation of the device 100, the first plurality of electrodes 146 and / or the second plurality of electrodes 148 can be charged to generate an electric field configured to accelerate positive ions or negative charges toward the substrate. The first plurality of electrodes 146 and / or the second plurality of electrodes 148 can be biased to generate a uniform electric field, particularly at or near the upper surface of the packaging substrate 10.

[0065] According to one embodiment, a device for contactless testing of a package substrate is provided. The device includes a vacuum chamber 101 and a platform 105 in the vacuum chamber. The platform is configured to support a package substrate 10, wherein the package substrate is a panel package substrate or an advanced package substrate. The device also includes a charged particle beam column 120 configured to generate an electron beam. The charged particle beam column includes: an objective lens 124 configured to focus the electron beam on the package substrate, a scanner configured to scan different positions on the package substrate, and an electron detector 140 for detecting signal electrons 113 emitted when the electron beam hits the package substrate. The device further includes: one or more electrodes configured to generate an electric field between one or more electrodes and the package substrate, the electric field being configured to accelerate positive ions or negative charges toward the substrate. Further, an analysis unit 141 is provided. The analysis unit determines whether the first device-to-device electrical interconnection path 20 is defective based on the signal electron 113.

[0066] According to some embodiments, which can be combined with other embodiments described herein, and as Figure 1B As shown, one or more electrodes can be installed in the charged particle beam column. For example, one or more electrodes can be positioned to direct signal electrons toward the detector. According to some embodiments that can be combined with other embodiments described herein, a gap is provided between one or more electrodes and the packaging substrate. In particular, a gap can be provided between at least one electron beam column and the packaging substrate.

[0067] According to some embodiments that can be combined with other embodiments described herein, such as Figure 1A The electric field exemplarily shown in and the electric field generated by the first plurality of electrodes and / or the second plurality of electrodes can be uniform, especially at the surface of the packaging substrate. The electric field can also be uniform between the surface of the packaging substrate and one or more electrodes. A uniform electric field in a region is constant at every point in the region. A uniform electric field has the same intensity and the same direction at every point and conforms to homogeneity, that is, all points experience the same physical conditions. Therefore, a uniform electric field can also be called a homogeneous electric field.

[0068] The first plurality of electrodes and / or the second plurality of electrodes may be used to guide the signal electrons during detection of the signal electrons and may be used to generate an electric field for charge control. According to additional or alternative modifications, the electric field may be generated by another electrode (e.g. Figure 1A The luminescent light may be generated by electrode 154 as shown, or by a combination of another electrode and the first plurality of electrodes and / or the second plurality of electrodes.

[0069] In some embodiments that can be combined with other embodiments described herein, the electron detector 140 comprises an Everhard-Thornley detector. An energy filter 142 for the signal electrons 113 can be arranged in front of the electron detector 140, in particular in front of the Everhard-Thornley detector, such as Figure 1B Schematic description of . The energy filter may include a grid electrode configured to be set at a predetermined potential. The energy filter 142 may enable low energy signal electrons to be suppressed. The energy filter 142 may suppress signal electrons that are not related to the voltage comparison measurement to be performed. In some embodiments, the energy filter 142 may suppress signal electrons emitted from uncharged surface areas and may only allow signal electrons emitted from charged surface contacts to pass. Therefore, the signal current detected by the electron detector may depend on the energy of the signal electrons that indicate whether the detected surface contact is defective.

[0070] In some embodiments, the device 100 may include a scanning controller 123 connected to a scanning deflector 122 of the charged particle beam column 120. The scanning deflector 122 may be configured to scan the electron beam on the substrate surface. The electron beam may be directed to a portion of the packaging substrate, for example, at a first beam probe diameter. The portion of the packaging substrate may be an area of ​​the packaging substrate where the electron beam is scanned or an area of ​​the packaging substrate. The electron beam may be raster scanned on the portion of the packaging substrate. For example, one or more scanning deflectors 122 may scan the electron beam on the portion of the packaging substrate. The portion of the packaging substrate may also 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 scanning deflectors may be used to scan the electron beam to one or more surface contacts.

[0071] For example, the scanning controller 123 can be configured to control the scanning deflector so that the electron beam is directed to each pair of first surface contacts and second surface contacts in sequence to test the corresponding inter-device electrical interconnection paths extending between the corresponding pairs of first surface contacts and second surface contacts. This allows for rapid and reliable testing of multiple electrical interconnection paths extending through the package substrate.

[0072] According to some embodiments that can be combined with other embodiments described herein, the electron beam can be vector scanned to various locations (such as surface contacts of a packaging substrate) for charging, and can be vector scanned to various locations to detect signal electrons. Alternatively, the electron beam can be vector scanned to various locations (such as surface contacts of a packaging substrate) for charging, and can be raster scanned or a certain area of ​​the packaging substrate to detect signal electrons. According to some embodiments that 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.

[0073] like Figure 1B , the electron source 121 is connected to a power supply 130. The power supply can provide a high voltage to the electron source so that an electron beam (i.e., a main electron beam) is emitted from the electron source. According to some embodiments that can be combined with other embodiments described herein, the voltage provided by the power supply 130 can be varied to change the energy of the electron beam and, therefore, change the landing energy of the electron beam 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, the power supply can be connected to the electron source (e.g., Figure 1B), connected to an extractor of the electron source, connected to an anode of the electron source, connected to a deceleration electrode configured to decelerate the electrons before impacting the package substrate, and / or connected to the platform 105. The landing energy of the electron beam on the package substrate is determined by the potential difference between the potential of the emitter tip of the electron source and the potential of the package substrate or the potential of the platform 105. Therefore, one or more power supplies may be provided to change the landing energy of the electron beam.

[0074] According to one embodiment, a device for contactless testing of a packaging substrate is provided. The packaging substrate is a panel packaging substrate or an advanced packaging substrate. The device includes a vacuum chamber 101 and a platform 105 in the vacuum chamber, wherein the platform is configured to support the packaging substrate, and the packaging substrate is a panel packaging substrate or an advanced packaging substrate. The device further includes an electron beam column configured to generate an electron beam, wherein the electron beam column includes: 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 hits the packaging substrate. The device further includes one or more electrodes configured to generate an electric field between the one or more electrodes and the packaging substrate, and the electric field is configured to accelerate positive ions or negative charges toward the substrate.

[0075] Figure 1B The platform 105 connected to the ground is illustrated as an example. The platform can be directly connected to the ground, such as Figure 1B The ground is exemplarily shown to be connected to the ground via a DC power supply, and may also be connected to the ground via an AC power supply. According to some embodiments that can be combined with other embodiments described herein, the platform may include a conductive platform surface directly or indirectly connected to the ground for providing a reference potential.

[0076] When the packaging substrate is placed on the platform 105, a prescribed charge is provided on the packaging substrate. In any case, the platform can be conductive. Therefore, the platform can be provided at a prescribed potential. For example, the prescribed potential can be a ground potential, or a potential that is negative or positive relative to the ground. For example, a DC power supply can be provided between the ground and the conductive platform. Alternatively, an AC power supply can be provided between the ground line and the conductive platform, wherein an alternating prescribed potential can be provided. According to some embodiments that can be combined with other embodiments described herein, the surface of the platform 105 is provided with a non-conductive material. For example, a layer of dielectric material can be provided as the surface of the platform. Having a non-conductive platform surface allows the charge applied to the packaging substrate to be maintained on the packaging substrate so that it can be detected during a test operation or a defect review operation.

[0077] According to some embodiments that can be combined with other embodiments described herein, the platform includes a conductive platform surface directly or indirectly connected to a ground line for providing a reference potential. According to further additional or alternative modifications, the packaging substrate can be partially connected to the ground, for example, through the platform. For example, some circuits can be connected to GND, while some circuits are not connected to the ground. According to further modifications that can be combined with other embodiments described herein, the packaging substrate can be capacitively connected to the ground, for example, through the platform. For some embodiments, there is no ohmic connection.

[0078] The prescribed potential of the platform, in particular a conductive platform, provides electric field lines, in particular at the platform surface and non-conductive parts of the package substrate. The prescribed potential can be used to influence the electron beam of the electron beam column.

[0079] According to further embodiments that can be combined with other embodiments described herein, the capacitive coupling of the package substrate to the platform 105 can provide a specified potential for the package substrate. For example, the capacitive coupling to ground can be provided by the grounded conductive platform 105. Additionally or alternatively, a predetermined set of structures on the package substrate can be connected to ground. However, the predetermined set of structures may not be charged due to grounding and can be used as a reference potential.

[0080] Figure 1B Controller 180 is shown. 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 device 100 for contactless testing of the package substrate and for charge control. Figure 1B As exemplarily shown in FIG. 1 , the controller may be connected to the power supply 130 , the scanning controller 123 , the analysis unit 141 , the ion source 152 , and the platform 150 . The controller may also be connected to the electron detector 140 .

[0081] The controller 180 includes a central processing unit (CPU), a memory, and, for example, a support circuit. To facilitate the control of the device for testing the package substrate, the CPU may be one of any form of general-purpose computer processors that can be used in an industrial environment to control various chambers and subprocessors. The memory is coupled to the CPU. The memory or computer-readable medium may be one or more readily available memory devices, such as random access memory, read-only memory, hard disk, or any other form of local or remote digital storage. The support circuit may be coupled to the CPU to support the processor in a conventional manner. These circuits include caches, power supplies, clock circuits, input / output circuit systems and related subsystems, and the like. Inspection processing instructions are generally stored in the memory as software routines (commonly referred to as recipes). The software routines may also be stored and / or executed by a second CPU (not shown) that is located at the remote end of the hardware controlled by the CPU. When the software routines are executed by the CPU, the general-purpose computer is transformed into a special-purpose computer (controller) to control the operation of the device, such as for controlling charge control, landing energy, platform positioning, and / or charged particle beam scanning during the test operation. Although the methods and / or processes of the present disclosure are discussed as being implemented as software routines, some of the method steps disclosed therein may also be implemented in hardware and by a software controller. Thus, embodiments of the present invention may be implemented as software executed on a computer system, as an application specific integrated circuit or other type of hardware implementation, or as a combination of software and hardware.

[0082] The controller may execute a method for testing a package substrate with an electron beam column. The method according to some embodiments includes the steps of generating ions and generating an electric field for charge control using ions. Further, the method includes the steps of testing the package substrate, in particular by directing an electron beam of at least one electron beam column onto at least a first portion of the package substrate and directing an electron beam of at least one electron beam column onto the package substrate. The method further includes the steps of detecting signal electrons emitted upon impact of the electron beam to test at least one first inter-device electrical interconnection path of the package substrate.

[0083] According to one embodiment, a device for testing a package substrate using any of the methods described herein is provided. The device may include a controller 180. The controller includes a processor and a memory storing instructions, which, when executed by the processor, cause the device to perform a method according to an embodiment of the present disclosure.

[0084] Figure 2A and 2BAn enlarged cross-sectional view of a package substrate during the test method described herein is shown. The package 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 (in Figure 2A and Figure 2B The surface contacts may be formed as or include solder bumps having a three-dimensional geometry (eg, a substantially hemispherical shape).

[0085] exist Figure 2A In the present invention, 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 charging electron beam 111 onto the first surface contact 21 and directing an electron beam onto the second surface contact 22. Since the first surface contact 21 is electrically connected to the second surface contact 22 through 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 carry 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 comparison can be used to characterize the defect. Further, the voltage comparison detected by subsequent measurements of adjacent electrical interconnection paths can be compared to find short circuits or leakage between different electrical interconnection paths.

[0086] After testing the first inter-device electrical interconnection path 20, the electron beam 111 can be directed to the two surface contacts of the second inter-device electrical interconnection path 23, for example by scanning the electron beam (vector scanning) to other positions with a corresponding scanning deflector and / or by moving the platform on which the package substrate is supported. Subsequently, multiple inter-device electrical interconnection paths can be tested with the charging electron beam and the detection electron beam. Therefore, multiple test points can be tested sequentially and / or in parallel.

[0087] exist Figure 2B In the embodiment of the present invention, an open circuit 151 exists in the first inter-device electrical interconnection path 20. The open circuit 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.

[0088] exist Figure 2BIn the embodiment, there is a short circuit 152 between the second inter-device electrical interconnection path 23 and the third inter-device electrical interconnection path 24. The short circuit can be determined because the third inter-device electrical interconnection path 24 is charged together with the second inter-device electrical interconnection path 23, which can be detected by a probing electron beam directed to another 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.

[0089] For evaluation and defect classification, measured signals of adjacent interconnect paths and / or previously collected data can be compared, allowing opens, shorts, and leaks in the package substrate to be identified.

[0090] Figure 3 is a schematic top view of the package substrate 10 being tested as described herein. The package substrate has a top surface having a plurality of surface contacts arranged in a 2-dimensional pattern. The package substrate 10 includes a first die connection interface 31 for attaching a first die (particularly by flip chip mounting), a second die connection interface 32 for attaching a second die (particularly by flip chip mounting), and optional other die connection interfaces, which can be arranged in pairs adjacent to each other. The first die connection interface 31 may include a plurality of first surface contacts (which are formed, for example, as solder bumps), and the second die connection interface 32 may include a plurality of second surface contacts (which are formed, for example, as solder bumps).

[0091] In some embodiments, each first surface contact of the first die connection interface 31 is connected to a corresponding second surface contact of the second die connection interface 32 via an inter-device electrical interconnection path. For the sake of clarity, only the inter-device electrical interconnection path connecting the first die connection interface and the second die connection interface is described. According to some embodiments that can be combined with other embodiments described herein, the first surface contact can be connected to a second surface contact. Alternatively, the first surface contact can be connected to two or more second surface contacts. The two or more second surface contacts can be detected with an electron beam, for example, after applying a charge to the first surface contact.

[0092] According to the test method described herein, the charged electron beam 111 is directed (especially focused) to the first surface contact of the first die connection interface 31, and the charged electron beam 111 is directed (especially focused) to the associated second surface contact of the second die connection interface 32. The signal electrons emitted from the second surface contact are detected to test whether there is an "open circuit" defect in the electrical interconnection path connecting the first surface contact and the second surface contact. Thereafter, the other surface contacts of the first die connection interface and the second die connection interface can be tested, especially in pairs.

[0093] Alternatively or additionally, it may be tested in parallel or subsequently whether charging of one inter-device electrical interconnect path results in charging of a surface contact of another inter-device electrical interconnect path, such that a "short" defect may be determined. For example, an electron beam may be rastered over a portion of a packaging substrate to produce an image of that portion of the packaging substrate. The image may be evaluated, for example, by pattern recognition.

[0094] Figures 4A to 4D Shown is an enlarged cross-sectional view of a package substrate that can be tested according to the methods described herein.

[0095] Figure 4A The package substrate 10 described in the embodiment has surface contacts on both main surfaces of the package substrate. For example, a first plurality of inter-device electrical interconnection paths may extend between a first surface contact and a second surface contact exposed on the upper substrate surface, and a second plurality of inter-device electrical interconnection paths may extend between a first surface contact and a second surface contact exposed on the lower substrate surface.

[0096] Figure 4B The package substrate 10 described in has at least one inter-device electrical interconnection path extending between at least three surface contacts 25 (ie, a first surface contact, a second surface contact, and at least a third surface contact).

[0097] Figure 4C The package substrate 10 described in the embodiment of the present invention has at least one inter-device electrical interconnection path extending between at least three surface contacts 25 exposed on different main surfaces of the substrate in a complex connection network. Such an inter-device electrical interconnection path can be configured to connect three or more dies to each other through the package substrate.

[0098] Figure 4D The package substrate 10 described in the embodiment has at least one interconnection bridge 29 embedded in the package 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 extending between the first die connection interface and the second die connection interface of the package substrate extend through the interconnection bridge. The interconnection bridge can be embedded in the package substrate during the manufacture of the package substrate. The interconnection bridge can be a bridge chip embedded in the package substrate for increasing the connection speed between multiple dies.

[0099] According to some embodiments that can be combined with other embodiments described herein, the testing methods and / or apparatus according to the present disclosure can be utilized during and / or after the manufacture of the packaging substrate. For example, the test can be applied on a packaging substrate that does not yet include all layers or structures. For example, the test can be performed after the redistribution layer (RDL) is manufactured and / or after the via layer is manufactured. RDL testing and / or via testing can be provided. Further, the test can be provided on the finished packaging substrate.

[0100] The test can be provided by charging (writing) one or more parts (such as surface contacts) and detecting (reading) the charge on the packaging substrate through signal electrons. The number of electrons emitted from the surface of the packaging substrate for each irradiated electron (i.e., the total electron yield) is related to the energy. For the case where the total electron yield is 1, the same number of electrons reaches the surface of the packaging substrate compared to the number of signal electrons emitted from the surface of the packaging substrate or scattered at the surface of the packaging substrate. There are two neutral energy values ​​(a first neutral energy value, a second neutral energy value), for which the total electron yield is equal to 1, i.e., there is no charging. According to some embodiments that can be combined with other embodiments described herein, the surface of the packaging substrate can be read using an electron beam having one of the neutral energy values, i.e., the signal electrons can be detected.

[0101] According to some embodiments that can be combined with other embodiments described herein, directing an electron beam having a first landing energy onto a portion of a packaging substrate can be a charging operation. The charging operation "writes" charge into an electrical interconnection path or a network of electrical interconnection paths. Further, directing an electron beam having a second landing energy onto a portion of a packaging substrate can be an operation for detecting signal electrons. The electron beam of the second landing energy can "read" the charge of an electrical interconnection path or a network of electrical interconnection paths.

[0102] According to some embodiments, which can be combined with other embodiments described herein, during the detection of signal electrons (i.e., reading the charge), charging of portions of the package substrate is reduced or avoided. In particular, while detecting signal electrons (e.g., detecting previously provided charge), the influence of the charge of an electrical interconnection path or a network of electrical interconnection paths is avoided or kept to a minimum.

[0103] For example, the electrical interconnection path network may include 5 surface contacts (or any number greater than 2). Charge may be applied (i.e., "written") to the first surface contact. The charge applied to the electrical interconnection path network may be "read" at the second surface contact. It is beneficial to not change the charge of the electrical interconnection path network having 5 surface contacts when "reading" the charge on the second surface contact to the fifth surface contact. Therefore, during the detection of signal electrons, the generation of charge may be reduced or avoided by using a neutral energy value for the landing energy.

[0104] The neutral energy value is material-dependent. The material of the packaging substrate or the material of the packaging substrate surface is known, and the landing energy can be adapted to the packaging substrate material for the method of testing the packaging substrate. The first neutral energy value can be several hundred eV. For a typical packaging substrate or a typical surface contact on the packaging substrate, the second neutral energy value can be between 1.5 keV and 2.5 keV. According to some embodiments that can be combined with other embodiments described herein, the landing energy for the testing 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 landing energy can be adapted depending on the test strategy, the material of the packaging substrate and / or the material of the surface contact.

[0105] For landing energies below the first neutral energy value, negative charging occurs, i.e., the total electron yield is less than 1. For landing 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. Related to the fact that the total electron yield is greater than 1 is the fact that more electrons leave the surface than the number of electrons that hit the surface. Therefore, the packaging substrate or structure is positively charged. For landing energies above the second neutral energy value, negative charging occurs, i.e., the total electron yield is less than 1. Related to the fact that the total electron yield is less than 1 is the fact that fewer electrons leave the surface than the number of electrons that hit the surface. The packaging substrate or structure is negatively charged.

[0106] According to an embodiment of the present disclosure, a test structure (e.g., various regions and / or surface contacts of a packaging substrate) can be positively charged or negatively charged by the impact of an electron beam. Depending on the relationship between the primary energy level (i.e., the landing energy) and the secondary electron yield, the total electron yield can be controlled. The potential of the test point can be determined. Defect detection can be performed using the voltage contrast principle. Further, sample parameter monitoring (such as capacitance resistance) can be provided. According to some embodiments that can be combined with other embodiments described herein, the landing energy can be changed to be higher or lower than the second neutral energy value. The landing energy of the electron beam is set to a predetermined landing energy and is positioned on a portion of the packaging substrate (e.g., a surface contact or test point on the packaging substrate). The electron beam stays on the portion of the packaging substrate for a specified time to positively charge or negatively charge the portion of the packaging substrate relative 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.

[0107] According to one embodiment, a method for testing a package substrate with at least one electron beam column is provided. The package substrate is a panel-level package substrate or an advanced package substrate. The method comprises the following steps: placing the package substrate on a platform in a vacuum chamber; flooding at least a portion of the vacuum chamber with positive ions and / or negative charges; generating an electric field between one or more electrodes and the package substrate, the electric field being configured to accelerate the positive ions or negative charges toward the substrate; and testing the package substrate in the vacuum chamber.

[0108] The packaging substrate described herein may be a panel-level packaging substrate or an advanced packaging substrate. Figure 5 As shown, the method is performed with an electron beam column and includes the following steps: (see operation 501) placing a package substrate on a platform in a vacuum chamber. In operation 502, ions are generated in the vacuum chamber. In particular, positive ions and / or negative charges are generated, which can fill at least a portion of the vacuum chamber. In operation 503, an electric field is generated between, for example, an electrode, a first plurality of electrodes 146 and / or a second plurality of electrodes 148 and the package substrate. Generating an electric field between one or more electrodes and the package substrate accelerates positive ions or negative charges toward the substrate. These charges are used for charge control, in particular, using a self-adjusting process. In operation 504, the package substrate is tested in the vacuum chamber.

[0109] For testing, at least one electron beam of at least one electron beam column is directed onto at least a first portion of the package substrate, and at least one electron beam of at least one electron beam column is directed onto at least a second portion of the package substrate. Signal electrons emitted upon impact of the at least one electron beam are detected to test a first inter-device electrical interconnection path of the package substrate.

[0110] According to some embodiments that 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 landing energy and onto at least a second portion with a second landing energy that is different from the first charging landing energy. For example, these signal electrons can be detected when the at least one electron beam strikes with the second landing energy to read the charge on the package substrate. For example, the second landing energy can be at or near a neutral energy value. For example, the read landing energy has a deviation of less than +-10% from a neutral energy value, which corresponds to a landing energy with a total electron yield of 1.

[0111] According to some embodiments that can be combined with other embodiments described herein, at least one electron beam can be focused when directing the electron beam onto at least a first portion of the packaging substrate and when directing the electron beam onto at least a second portion of the packaging substrate. According to further modifications that can be combined with embodiments of the present disclosure, the electron beam is fixed to one or more locations on the packaging substrate for charging and detecting signal electrons. Further, additionally or alternatively, a method can include energy filtering the signal electrons.

[0112] Embodiments of the present disclosure may include methods for testing a package substrate, such as Figure 6 In operation 601, an advanced packaging substrate or a panel-level packaging substrate may be loaded into a test chamber, for example, Figure 1B 1. In operation 602, the package substrate is moved under the electron beam column. The electron beam test or electron beam test sequence may include charging and reading the test points (i.e., surface contacts on the package substrate). The test of the package substrate may include the following steps: directing at least one electron beam of at least one electron beam column onto at least a first portion of the package substrate; directing at least one electron beam of at least one electron beam column onto at least a second portion of the package substrate; and detecting signal electrons emitted when the at least one electron beam strikes to test a first inter-device electrical interconnection path of the package substrate.

[0113] For example, at least one electron beam can be directed onto at least a first portion at a first landing energy and onto at least a second portion at a second landing energy different from the first landing energy. Signal electrons are detected when the at least one electron beam strikes at the second landing energy to read the charge on the package substrate.

[0114] In operation 603, the vacuum chamber or at least a portion of the vacuum chamber is filled with ions, particularly near the encapsulation substrate. Therefore, ions can fly between the encapsulation substrate and the positive electrode or negative electrode. The electrode can be an electrode used during the operation of the charged particle beam column. The electric field provided between the substrate and the electrode accelerates the positive ions or negative charges toward the encapsulation substrate. Particles with opposite charges are attracted by the electrode (e.g., the electrode or part of the charged particle beam column). In operation 604, these charges neutralize the charges on the encapsulation substrate. The encapsulation substrate can be set to a specified charge condition. For example, the encapsulation substrate can be set to a specified potential relative to grounding. In operation 605, the ion source can be turned off. Further, in a mode for testing operation, the electric field can be turned off or changed. The electron beam test is provided with charging of the contact points and reading of the contact points.

[0115] According to some embodiments that can be combined with other embodiments described herein, operations 603 and 604 can be provided during an electron beam test sequence or between different electron beam test sequences. During the testing of the package substrate, an intermediate ion discharge step can be provided. Due to the specified starting conditions of the contact points or test points (especially all contact points or test points), the charge control described herein provides a better signal-to-noise ratio for testing the package substrate with an electron beam. A uniform overall charge control method for the entire test area can be provided. Further, since the charge control process is self-adjusting, a homogeneously charged package substrate can be provided. Self-adjustment is based in particular on the fact that, for example, more negatively charged areas will attract more positive ions until the entire package substrate reaches equilibrium. As described above, the test operation according to the embodiments of the present disclosure is contactless and can be provided independently of the test feature size and / or morphology.

[0116] Figures 7A to 7C The effect of charge control according to the embodiment of the present disclosure is shown. Fig. 7A As shown in Figure 1, images produced with a charged particle beam column without preconditioning by ions show poor uniformity and high noise. As a result, different electron beam positions on the package substrate result in different signal levels. The correlation between the sample potential and the signal electrons of the voltage contrast measurement is reduced. Figure 7B Similar images are shown with preprocessing. For example, about 5*10 -3 Pa to about 1*10 -1 Pa (about 5*10 -2 Pa) can produce an ion density that is beneficial for charge control. SEM images show improved uniformity and lower signal noise. Different electron beam positioning on the package substrate will result in the same signal level. It can provide a good correlation between the sample potential and the voltage contrast measurement. At lower pressures, such as about 5*10 -4 Pa, the ion density is low and may not lead to efficient sample discharge at such pressures. Figure 7C The images shown show little improvement in uniformity or signal-to-noise ratio. Thus, embodiments of the present disclosure can result in better defect detectability and more accurate measurement of parameters, such as capacitance.

[0117] Embodiments of the present disclosure provide electron beam testing, particularly including electron beam writing and electron beam reading of charges on a packaging substrate, particularly for generating specified measurement conditions and / or starting conditions. According to some embodiments that can be combined with other embodiments described herein, at least one electron beam can be focused when the electron beam is directed 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.

[0118] Embodiments of the present disclosure provide one or more of the following advantages. A contactless electrical test of a package substrate as disclosed herein can be provided, wherein charge can be controlled for electrical defect detection. In view of the flexibility of the electron beam, a higher test speed can be provided. Due to the specified conditions of various or all test points (i.e., surface contacts), an improved signal-to-noise ratio can be provided. A complete and uniform full test area charge control method can be provided. The charge control is self-adjusting. During mass production, testing of 100% of the electrical interconnect paths is possible. Further, the flexibility of the electron beam allows testing and flexible setup of different AP / PLP substrate layouts. The test methods and apparatus disclosed herein are independent of the test feature size and further allow scalability to smaller sizes, especially if technology development moves towards smaller structure sizes. Testing of the package substrate is non-destructive.

[0119] While the foregoing is directed to certain embodiments, other and further embodiments may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims which follow.

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, the method comprising the following steps: Placing the packaging substrate (10) on a platform (105) in a vacuum chamber (101); flooding at least a portion of the vacuum chamber with positive ions and / or negative charges; generating an electric field between one or more electrodes and the packaging substrate, the electric field being configured to accelerate the positive ions or the negative charges toward the substrate; as well as The package substrate is tested in the vacuum chamber using at least one electron beam column.

2. The method according to claim 1, wherein the step of filling the vacuum chamber with the positive ions and / or negative charges is provided by an ion source at least partially arranged in the vacuum chamber.

3. The method of claim 2, wherein the ion source is selected from the group consisting of: an ion source with a gas supply, a VUV source, a spark generating the positive ion source. 4 . The method according to claim 1 , wherein the electric field is uniform at the surface of the packaging substrate, or wherein the electric field is uniform between the surface of the packaging substrate and the one or more electrodes. 5 . The method according to claim 1 , wherein a space is provided between the one or more electrodes and the packaging substrate.

6. The method according to any one of claims 1 to 4, wherein a space is provided between the at least one electron beam column and the packaging substrate.

7. The method according to any one of claims 1 to 6, wherein the step of testing the package substrate comprises the following steps: 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 the at least one electron beam of the at least one electron beam column onto at least a second portion of the packaging substrate; as well as Signal electrons emitted upon impact of the at least one electron beam are detected to test a first inter-device electrical interconnect path of the packaging substrate.

8. The method of claim 7, wherein the at least one electron beam is directed onto at least the first portion with a first landing energy and is directed onto at least the second portion with a second landing energy different from the first landing energy.

9. The method of claim 8, wherein the signal electrons are detected when the at least one electron beam strikes with the second landing energy to read the charge on the packaging substrate.

10. An apparatus for testing a package substrate according to the method of any one of claims 1 to 9.

11. A device (100) for contactless testing of a package substrate (10), the device comprising: A vacuum chamber (101); A platform (105), the platform is located in the vacuum chamber, the platform is configured to support the packaging substrate, the packaging substrate is a panel-level packaging substrate or an advanced packaging substrate; A charged particle beam column (120), the charged particle beam column being configured to generate an electron beam, the charged particle beam column comprising: an objective lens (124), the objective lens being configured to focus the electron beam onto the packaging substrate; a scanner configured to scan the electron beam to different positions on the packaging substrate; and An electron detector (140), the electron detector being used to detect signal electrons (113) emitted when the electron beam strikes the packaging substrate; The device further comprises: one or more electrodes configured to generate an electric field between the one or more electrodes and the packaging substrate, the electric field configured to accelerate positive ions or negative charges toward the substrate; and An analysis unit (141) is used to determine whether the first inter-device electrical interconnection path (20) is defective based on the signal electron (113).

12. The apparatus of claim 11, wherein the one or more electrodes are disposed in the charged particle beam column.

13. The apparatus of claim 12, wherein the one or more electrodes are positioned to direct signal electrons toward the detector.

14. The apparatus according to any one of claims 11 to 13, wherein the one or more electrodes are at least one assembly of four or eight electrodes, the at least one assembly being configured to generate a multipole field for guiding signal electrons.

15. The apparatus according to any one of claims 11 to 14, wherein the platform comprises: The conductive platform surface is directly or indirectly connected to the ground line to provide a reference potential.

16. The apparatus according to any one of claims 11 to 15, wherein the electron detector (140) comprises: An energy filter (142) is provided for the signal electrons (113).

17. The apparatus according to claim 11 or 16, further comprising: A scan controller (123) is configured to sequentially direct the electron beam to the pairs of first surface contacts and second surface contacts to test corresponding inter-device electrical interconnection paths extending between the corresponding pairs of first surface contacts and second surface contacts.

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