Method for testing a packaging substrate and apparatus for testing a packaging substrate

Abstract

A method for testing a packaging substrate using at least one electron beam column is described. The packaging substrate is a panel level packaging substrate or an advanced packaging substrate. The method includes placing the packaging substrate on a stage within a vacuum chamber, filling 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 positive ions or negative charges towards the substrate, and testing the packaging substrate within 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, the embodiments described herein relate to non-contact testing of electrical interconnections within a packaging substrate, i.e., a panel-level packaging (PLP) substrate or an advanced packaging (AP) substrate, using an electron beam, and in particular to non-contact testing for identifying, characterizing, detecting, and / or classifying defects such as short circuits, open circuits, and / or leaks.

Background Art

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

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

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

[0005] The complexity of packaging substrates is increasing, and the design rules (feature sizes) are significantly decreasing. Within such substrates, surface contacts (for subsequent flip-chip mounting or other chip mounting) are connected to other surface contacts on the packaging substrate in order to interconnect semiconductor devices (or other devices). Standard methods, such as electromechanical probing for electrical testing, cannot meet the requirements of high-volume production testing because throughput decreases (the number of test points increases) and contact reliability decreases (contact sizes become smaller). In addition to size reduction and the problem of potentially damaging contact pads, other test methods, such as test methods using capacitance detectors or electric field detectors, are hampered by the topography of the packaging substrate. This is because such methods benefit from having small mechanical clearances.

[0006] Accordingly, it would be beneficial to provide test methods and test apparatuses suitable for rapidly testing complex microelectronic devices, particularly packaging substrates such as AP substrates and PLP substrates, with high reliability. SUMMARY OF THE INVENTION

[0007] In view of the above, a method and an apparatus for testing a packaging substrate according to independent claims are provided. Additional aspects, advantages, and advantageous features will be apparent from the dependent claims, the description, and the accompanying drawings.

[0008] According to one embodiment, a method for testing a packaging substrate using at least one electron beam column is provided. The packaging substrate is a panel level packaging substrate or an advanced packaging substrate. The method includes placing the packaging substrate on a stage within a vacuum chamber, filling 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 positive ions or negative charges towards the substrate, and testing the packaging substrate within the vacuum chamber using at least one electron beam column.

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

[0010] According to one embodiment, an apparatus for non-contact testing of a packaging substrate is provided. The apparatus includes a vacuum chamber, a stage within the vacuum chamber, the stage being configured to support a packaging substrate that is 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 onto 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 collides with the packaging substrate. The apparatus 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 towards the substrate, and an analysis unit for determining whether a first inter-device electrical interconnect path has a defect based on the signal electrons.

[0011] Embodiments are also directed to apparatus for performing the disclosed methods and include apparatus components for performing each of the described method aspects. These method aspects may be performed as hardware components, as computers programmed by appropriate software, by any combination of these two, or in any other manner. Further, embodiments in accordance with 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. The methods for operating the described apparatus include method aspects for performing any of the functions of the apparatus.

[0012] By referring to the embodiments, a more detailed description of the present disclosure, briefly outlined above, can be obtained so that the features of the present disclosure listed above can be understood in detail. The accompanying drawings relate to embodiments of the present disclosure, and the description of the accompanying drawings is set forth below.

Brief Description of the Drawings

[0013]

Figure 1A

Figure 1B

Figures 2A-2B

Figure 3

Figures 4A-4D

Figure 5

Figure 6

Figures 7A-7C

DETAILED DESCRIPTION OF THE INVENTION

[0014] Next, various exemplary embodiments will be referred to in detail. One or more examples of those embodiments are shown in each figure. Each example is shown for illustrative purposes and is not meant to be limiting. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield additional embodiments. The present disclosure is intended to embrace such changes and modifications.

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

[0016] Embodiments of the present disclosure relate to testing and / or defect review of packaging substrates, namely panel level packaging (PLP) substrates or advanced packaging (AP) substrates, by the methods described herein. In order to write charges on the packaging substrate and read the charges on the packaging substrate, at least one electron beam is used, in particular for the purpose of identifying and characterizing defects such as short circuits, open circuits and / or leaks, and writing and reading charges. A non-contact electrical test using an electron beam can be provided, in which a reading of a voltage signal, for example a voltage contrast by sensing signal electrons, is provided. According to some embodiments that can be combined with other embodiments described herein, the voltage contrast on the packaging substrate may be determined by detecting signal electrons. According to some embodiments that can be combined with other embodiments described herein, the signal electrons may be particularly secondary electrons. Furthermore, the test points or contacts on the AP or PLP substrate can be charged non-contact. The non-contact test prevents or reduces damage to the AP / PLP substrate. Detection and classification of electrical defects are made possible. Charge control is provided to further improve the voltage contrast in the method according to an embodiment of the present disclosure and in the device according to an embodiment of the present disclosure. The packaging substrate can be discharged or charged to defined conditions. By discharging the test substrate to defined starting conditions regarding potential and charge distribution, a reproducible voltage contrast signal by SE (signal electrons) and an improved defect detection success rate (S / N ratio, signal-to-noise ratio) on some substrates as well as an improved defect detection success rate (S / N ratio, signal-to-noise ratio) after repeated e-beam scanning and test sequences can be provided. According to an embodiment of the present disclosure, an ion source is utilized to control the charge condition of the AP or PLP substrate. A defined directed electric field is provided. The electric field separates positive ions from negative ions and induces the positive ions towards the substrate. According to some embodiments that can be combined with other embodiments described herein, the ion source and the electric field electrodes can be incorporated into a vacuum test chamber.Any residual negative charge of positive ions on the substrate is advantageous for the subsequent e-beam test signal-to-noise ratio. Further, the positive ions may provide a positive potential bias to the test substrate, which may be advantageous for subsequent e-beam testing.

[0017] According to one embodiment, a method for testing a packaging substrate using at least one electron beam column is provided. The packaging substrate is a panel-level packaging substrate or an advanced packaging substrate. The method includes placing the packaging substrate on a stage within 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 packaging substrate, the electric field being configured to accelerate the positive ions toward the substrate, and testing the packaging substrate within the vacuum chamber.

[0018] FIG. 1A shows a schematic diagram of an apparatus illustrating the concept of charge control. A packaging substrate 10 is supported on a stage 105. The packaging substrate is supported within a vacuum chamber 110. According to some embodiments that can be combined with other embodiments described herein, one or more ion sources are placed within the vacuum chamber 110 or at least partially within the vacuum chamber. FIG. 1A shows an ion source 152. The ion source 152 generates positive ions and negative charges. The vacuum chamber or at least a portion of the vacuum chamber is filled with positive ions and negative charges. According to embodiments of the present disclosure, the negative charge may be an electron or a negative ion. Below, accelerating positive ions toward the substrate is described. However, by changing the potential of the components exemplarily shown in FIG. 1A, negative ions or electrons may also be accelerated toward the substrate.

[0019] Electrode 154 generates an electric field 155. As shown in FIG. 1A, the electric field 155 accelerates positive ions toward the packaging substrate 10. Accordingly, positive charges are provided on the packaging substrate 10. For the electrode 154 that is at a negative potential compared to the substrate, negative ions or electrons are accelerated toward the packaging substrate. Accordingly, negative charging can be provided on the packaging substrate.

[0020] According to some embodiments that can be combined with other embodiments described herein, the ion source 152 can be selected from an ion source including a gas supply source, a UV source such as a VUV source, a spark generation unit, or another ion generation unit. For example, a VUV source that generates ions may ionize residual gas in the vacuum chamber, and in that case, the ion density can be controlled by, for example, the base pressure and the mean free path of the ion generic orbit. According to some embodiments that can be combined with other embodiments described herein, the ion source provided at least partially within the vacuum chamber provides to fill the vacuum chamber with positive ions and / or negative charges.

[0021] As shown in FIG. 1B, ions are released from the ion source 152 and distributed within the vacuum chamber 110. In particular, the ions can be distributed between the stage 105 and the electrode 154. The electric field 155 separates positive ions and negative ions or electrons, respectively. According to some embodiments that can be combined with other embodiments described herein, the packaging substrate 10 can be placed on the stage 105 at ground potential and the positively charged electrode 154. The voltage between the electrode 154 and the stage can be provided by the power supply 106. As shown in FIG. 1B, the electrode 154 can be a separate element provided within the test apparatus, or as shown in FIG. 1B, the electrode 154 can also be incorporated into the charged particle beam column.

[0022] According to the embodiments mainly described in the present disclosure, positive ions are pushed towards the substrate, while negative ions or electrons are accelerated towards the positive charge electrode 154. A self-aligning process that provides a uniform charge distribution is provided. For example, if a first area of the packaging substrate 10 is more positively charged than a second area of the packaging substrate 10, the first area is exposed to a smaller electric field during the subsequence charge control operation and thus receives a lower positive charge. In any area of the substrate within a uniform electric field, when the ions compensate for the electric field applied by the electrodes, the deposition of ions onto the substrate stops.

[0023] Therefore, by controlling the intensity of the electric field, the substrate can be charged to a specified potential. For example, an electrode 154 charged to +100V will make the electric field zero when charges accumulate on the substrate 10 in such a manner that the substrate is also biased at +100V. Therefore, the substrate potential can be adjusted to a predetermined value.

[0024] According to some embodiments that can be combined with other embodiments described herein, before testing the packaging substrate, for example, before testing the packaging substrate using a charged particle beam column that directs an electron beam onto a portion of the packaging substrate, residual positive or negative charges on or within the loaded test substrate can be neutralized by negative charges or positive ions. Additionally, optionally, the test substrate can also be 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, it is to charge the substrate to a specified potential, for example, a specified potential with respect to ground. Regarding subsequent e-beam testing, advantageously, it may provide a higher voltage contrast between the positive substrate and the negatively charged test structures on the sample.

[0025] According to embodiments of the present disclosure, embodiments of the present disclosure set a packaging substrate to a defined starting condition (charge distribution), for example, a uniform starting condition (charge distribution), for better defect detectability and reproducibility. Thus, a defined starting condition, particularly a defined starting condition for all test points, can provide an improved signal-to-noise ratio for e-beam measurement.

[0026] As described with respect to FIG. 1B and FIGS. 5 and 6, a method for testing a packaging substrate is provided. The packaging substrate is a panel level packaging substrate or an advanced packaging substrate. The method implemented using at least one electron beam column includes placing the packaging substrate on a stage within a vacuum chamber.

[0027] According to some embodiments that can be combined with other embodiments described herein, at least one electron beam is directed with a first incident energy onto at least a first portion and with a second incident energy different from the first charged incident energy onto at least a second portion. For example, signal electrons can be detected when at least one electron beam collides with a second energy for reading charges on the packaging substrate. Charge control is provided by generating positive ions or negative charges before, between, and / or after the test sequence, for example, by neutralizing negative charges on the packaging substrate.

[0028] To reduce the spatial requirements of semiconductor packages, the complexity of packaging substrates has been continuously increasing over the years. To reduce manufacturing costs, packaging techniques such as 2.5D IC, 3D-IC, and wafer level packaging (WLP), such as fan-out WLP, have been proposed. In the WLP technique, integrated circuits are packaged before dicing. As used herein, "packaging substrate" relates to a packaging substrate configured for advanced packaging techniques, particularly WLP techniques or panel level packaging (PLP) techniques.

[0029] "2.5D integrated circuits" (2.5D ICs) and "3D integrated circuits" (3D ICs) couple multiple dies within 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 a 2.5D IC, the dies are placed side by side on the packaging substrate, and in a 3D IC, at least some of those dies are placed on top of each other. The assembly can be packaged as a single component, thereby reducing cost and size compared to conventional 2D circuit board assemblies.

[0030] The packaging substrate typically includes multiple inter-device electrical interconnect paths for providing electrical connections between chips or dies placed on the packaging substrate. Those inter-device electrical interconnect paths extend through the body of the packaging substrate in a complex network of connections, vertically (perpendicular to the surface of the packaging substrate) and / or horizontally (parallel to the surface of the packaging substrate), and endpoints (referred to herein as surface contacts) are exposed on the surface of the packaging substrate.

[0031] An advanced packaging (AP) substrate provides inter-device electrical interconnect paths on a wafer, such as on a silicon wafer or within a wafer, such as within a silicon wafer. For example, the AP substrate may include through-silicon vias (TSVs), which are other conductors extending through the AP substrate, such as through-silicon vias (TSVs) provided within a silicon interposer. A panel-level packaging substrate is provided from a composite material, such as from a printed circuit board (PCB) material, or from another composite material including, for example, ceramic and glass materials.

[0032] 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 a plurality of chips, dies, or AP substrates placed on its surface, e.g., on one or both of its sides, and electrical interconnect paths between the plurality of devices that extend through the body of the PLP substrate.

[0033] Note 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 may have another shape. Specifically, the panel-level substrate may provide a surface area larger than the surface area of a typical wafer, e.g., a surface area of 1000 cm 2 or more. For example, the panel-level substrate may have a size of 30 cm × 30 cm or more, 60 cm × 30 cm or more, 60 cm × 60 cm or more.

[0034] According to embodiments of the present disclosure, an e-beam test and / or e-beam review provides testing of contact pads that are 60 μm or less, or rather about 10 μm or less. Voltage contrast test imaging can be provided. The test can be provided at the "surface contacts" of the packaging substrate or between the "surface contacts" of the packaging substrate.

[0035] "Surface contact points" may be understood as the endpoints of electrical interconnection paths exposed on the surface of a packaging substrate in such a manner that an electron beam can be directed onto the surface contact points for non-contact charging or exploration of the electrical interconnection paths. The surface contact points are configured to be in electrical contact with chips, dies, smaller packages, or other electrical components, such as capacitors, resistors, coils, or other similar ones, placed on the surface of the packaging substrate, for example, by soldering. The electrical components may further include active electrical components, such as transformers that change the voltage in the area of the package. In some embodiments, the surface contact points may be solder bumps or may include solder bumps.

[0036] According to embodiments of the present disclosure, 100% of the electrical interconnection paths are tested. The ownership cost of a device package, including chips such as processors, memories, or other similar ones (microelectronic devices), is mainly determined by those highly integrated microelectronic devices. Therefore, mounting microelectronic devices without defects on a packaging substrate with defects is disadvantageous in terms of manufacturing cost. It is desirable that the packaging substrate has no defects at all before mounting the microelectronic devices.

[0037] The present disclosure relates to a method and an apparatus for testing a packaging substrate configured to integrate a plurality of devices into one integrated package and including at least one inter-device electrical interconnection path. According to embodiments of the present disclosure, a test system, a test apparatus, or a test method may detect and / or classify electrical connections having defects, such as open circuits, short circuits, leakage defects, or others, in the packaging substrate. In particular, those test methods and test systems may provide non-contact testing. A contact pad pitch of 60 μm or less, or rather about 10 μm or less, is difficult or rather impossible for mechanical exploration. Furthermore, those small contact pads must not be damaged by scratching. Non-contact testing is beneficial.

[0038] According to some embodiments that can be combined with other embodiments described herein, by operating an electron beam column at a defined incident energy, additional charge control during charge writing can be provided. In particular, in order to control the charge provided on a packaging substrate, the incident energy, i.e., the energy of the electron beam at the time of collision with the packaging substrate, can be changed. By changing the incident energy, the collision 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. A non-contact electrical test can be provided using an e-beam, wherein the charge can be placed, 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 on the packaging substrate. Different e-beam incident energies (Upe) control the SE yield (secondary electron yield), and thus the total electron yield. On some substrates, and / or after repeating the e-beam scanning and test sequence, it is beneficial to discharge the test substrate to defined starting conditions, such as conditions regarding potential and charge distribution, in order to achieve a voltage contrast signal with good reproducibility.

[0039] According to some embodiments that can be combined with other embodiments described herein, a method for testing a packaging includes placing a packaging substrate on a stage within a vacuum chamber, directing an electron beam of at least one electron beam column onto at least a first portion of the packaging substrate at a first incident energy, and directing an electron beam of 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 during the collision of the electron beam to test at least a first inter-device electrical interconnect path of the packaging substrate.

[0040] It is possible to provide a test of characteristics of a packaging substrate, for example, a test of an electrical interconnection path of the packaging substrate, and at this time, the charging of the characteristics and / or the packaging substrate can be controlled. The e-beam primary energy (U pe ), that is, by changing the incident energy of the electron beam incident on the packaging substrate, the charge on the packaging substrate or the charge on each part of the packaging substrate can be controlled. The test may include reading a voltage signal, that is, measuring a voltage contrast when detecting signal electrons, for example, secondary electrons. In order to avoid damage to the surface contacts, the test position of the advanced packaging substrate or the panel-level packaging substrate, that is, the surface contacts can be charged without contact.

[0041] FIG. 1B shows a schematic cross-sectional view of an apparatus 100 for testing a packaging substrate 10 according to an embodiment described herein. The apparatus 100 includes a vacuum chamber 101, and the vacuum chamber 101 may be a test chamber specifically configured for testing, or may be one of the vacuum chambers of a larger vacuum system, for example, a processing chamber of a packaging substrate manufacturing system or a packaging substrate processing system.

[0042] As schematically shown in FIG. 1B, the packaging substrate 10 includes a first inter-device electrical interconnection path 20 that extends 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, and those three or more surface contacts may be provided on the same surface of the packaging substrate, or may be provided on two opposite surfaces. The inter-device electrical interconnection paths 20 shown in FIG. 1B extend only between a first surface contact 21 and a second surface contact 22 that are both disposed on the top surface of the packaging substrate, but the present disclosure is not limited to only such inter-device electrical interconnection paths. The inter-device electrical interconnection path may extend through the packaging substrate and may be a complex network of vias, pillars, and / or conductive lines having a plurality of surface contacts.

[0043] The packaging substrate 10 may include a plurality of inter-device electrical interconnection paths 20 for connecting a plurality of devices placed on the packaging substrate 10. Although three inter-device electrical interconnection paths are exemplarily shown in FIG. 1B, the packaging substrate 10 may include thousands or tens of thousands of inter-device electrical interconnection paths that are normally electrically isolated from each other as long as there is no short circuit between two electrical interconnection paths.

[0044] According to the embodiments described in this specification, the packaging substrate 10 is placed on the stage 105 within the vacuum chamber 101. The stage can be movable, and in particular, it can be movable in the z direction (i.e., the direction perpendicular to the surface of the stage) and / or in the x and y directions (i.e., the directions within the plane of the surface of the stage). The stage 105 is provided within the vacuum chamber and is configured to support the packaging substrate, which is one of the panel-level packaging substrate and the advanced packaging substrate. The electron beam 111 is guided onto the first surface contact 21. The electron beam can be scanned and guided to the second surface contact 22. To test the first inter-device electrical interconnection path 20, the 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 can be determined whether the first inter-device electrical interconnection path 20 has an "open circuit" defect.

[0045] Alternatively, or in addition, the electron beam 111 may be guided onto an additional surface contact 27 that is not an endpoint of the first inter-device electrical interconnection path 20, i.e., an additional surface contact 27 belonging to a second inter-device electrical interconnection path 23 that extends through the packaging substrate adjacent to the first inter-device electrical interconnection path 20. To test the first inter-device electrical interconnection path 20, the signal electrons emitted from the additional surface contact 27 are detected. The signal electrons may be secondary electrons and / or backscattered electrons. For example, it can be determined whether the first inter-device electrical interconnection path 20 has a "short circuit" defect.

[0046] In particular, by detecting the signal electrons 113 emitted when the electron beam 111 collides with the packaging substrate (in particular, by determining the energy of the signal electrons 113 that depends on the potential of the second surface contact 22 or the additional surface contact 27), it is possible to determine whether the first inter-device electrical interconnection path 20 has a defect in "voltage contrast measurement". Specifically, it is possible to determine and classify the connections having defects in the packaging substrate, for example, classify them into open circuits, short circuits and / or leakage defects.

[0047] In some embodiments that can 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 surfaces of the substrate are inspected. For example, one or more electron beam columns may be disposed 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 each electrical connection.

[0048] 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. Further, the contact reliability of electrical and / or mechanical testers decreases with the reduction in the size of the surface contacts of the test object within the advanced packaging substrate, as well as the increase in the density and number of surface contacts. For example, it is difficult to have a contact pad size of less than 30 μm for mechanical probing. Further, with respect to other inspection methods, such as capacitive detectors 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 charged electron beam is further advantageous, for example, compared to flood gun electron charging. Considering the complexity of the packaging substrate, the capacitance of local charging improves the available test procedures compared to charging the entire area using a flood gun. Further, local charging reduces the total charge accumulated on the packaging substrate. Further, different chargings of different areas may result in a reduction in the total charge provided on the substrate. For example, if one area is positively charged and another area is negatively charged, the total charge can be maintained near neutral. According to some embodiments that can be combined with other embodiments described herein, different charge patterns can be provided to a plurality of portions of the packaging substrate.

[0049] The test methods described in this specification are suitable for testing packaging substrates for multi-device in-package integration, and in particular, are suitable for testing panel-level packaging substrates (PLP substrates) or advanced packaging substrates (AP substrates). The e-beam is used for both the purpose of charging the inter-device electrical interconnection path 20 and the purpose of reading the voltage of the charged circuit, in particular by probing the second surface contact and / or additional surface contacts. In other words, using the electron beam, both "electrical driving" and "probing" are performed in such a manner that defects can be quickly found with high reliability. The tests by e-beam charging and e-beam probing (e.g., using an EBT column or an EBR column) are independent of topography, fast, flexible with respect to contact position, size, and shape dimensions, while for other test methods such as capacitance detectors or electric field detectors, the topography of the packaging substrate can be a problem.

[0050] Packaging substrates such as PLP substrates may include a plurality of device connections, for example, 5,000 or more, 10,000 or more, 20,000 or more, or even 50,000 or more device connections. The connections may include through-silicon electrodes (TSVs), such as through-silicon electrode 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 interconnections within a plurality of layers arranged on top of each other, for example, within a layer stack.

[0051] In some embodiments, the packaging substrate 10 includes a plurality of inter-device electrical interconnect paths extending between respective first and second surface contacts and optional additional contacts, and the method may include sequentially or in parallel testing those plurality of inter-device electrical interconnect paths. As used herein, "sequential testing" refers to the subsequent testing of the plurality of inter-device electrical interconnect paths of the packaging substrate. For example, testing more than 5,000 inter-device electrical interconnect paths sequentially. 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 some of the inter-device electrical interconnect paths by scanning an electron beam over some of the first surface contacts to charge a field of view while scanning the electron beam over corresponding some of the second surface contacts to probe the same field of view.

[0052] 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, such that the beam probe diameter on the packaging substrate is 30 μm or less, particularly 10 μm or less. Focusing the charged electron beam onto the packaging substrate using, for example, an objective lens can prevent charging of substrate surface areas different from the surface contact and can provide more accurate test results. In addition to, or instead of, generating an image of a portion of the packaging substrate, the electron beam may be scanned across a portion of the packaging substrate, particularly to detect the signal electron beam. The image may include voltage contrast information. For example, defect detection or classification of one or more electrical interconnect paths can be provided by pattern recognition within the image.

[0053] Conventional PCBs typically include relatively large planar metal pads that form surface contacts for testing, but the packaging substrates to be tested according to the embodiments described herein may include a vast number of small convex solder bumps that are the subject of testing, which makes the 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, particularly 10 μm or less. For example, the first and second surface contacts may essentially be spherical with a diameter of 25 μm or less, particularly 10 μm or less, and particularly hemispherical. According to some embodiments that can be combined with other embodiments described herein, the surface contacts may have a three-dimensional topography, particularly a substantially hemispherical three-dimensional topography.

[0054] In contrast to mechanical testers, an electron beam can be focused to a very small probe diameter and accurately directed to a predetermined point on the substrate, for example with the use of a scanning deflector, with an accuracy in the sub-μm range, so that the electron beam can be accurately directed onto such a small surface area. Other testers may slip or slide from surface contacts having a convex shape dimension, but the electron beam can be accurately focused onto any shape dimension in such a manner that the test methods described herein are shape dimension independent and topography independent.

[0055] As schematically shown in FIG. 1B, a charged particle beam column 120 may be provided on a first side of the stage 105. In some embodiments that can be combined with other embodiments described herein, the charged particle beam column 120 may have an electron source 121 for generating an electron beam and beam optical elements, such as a scanning deflector 122 and / or an objective lens 124, for directing a first electron beam onto a substrate placed on the stage 105. The objective lens 124 may be an electrostatic objective lens (shown in FIG. 1B), a magnetic objective lens, or a magnetostatic objective lens.

[0056] The apparatus 100 further includes an electron detector 140 for detecting signal electrons 113 emitted when a second electron beam collides with the packaging substrate, and an analysis unit 141 configured to determine whether the first inter-device electrical interconnection 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 interconnection 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 defects. In some embodiments, the analysis unit 141 may be configured to determine whether there is a short circuit or a leak between two or more electrical interconnection paths based on the detected signal electrons from subsequent measurements. In some embodiments, the signal electrons 113 detected by the electron detector 140 may provide information regarding the potential of the substrate position from which the signal electrons 113 were emitted or reflected, and the analysis unit 141 may be configured to determine whether the first inter-device electrical interconnection path 20 has a defect from the said information. The analysis unit 141 may be further configured to classify the determined defects. Specifically, 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 to be 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 to be an electrical connection between two electrical interconnection paths that should actually be electrically separated.

[0057] The charged particle beam column 120 shown in FIG. 1B includes a first plurality of electrodes 146 and a second plurality of electrodes 148. The first plurality of electrodes 146 can generate a multipole field, such as an octupole field, for guiding the signal electrons 113 towards the electron detector 140. For example, the first plurality of electrodes can include eight or more electrodes for generating an octupole field. In particular, the multipole 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 multipole field, such as an octupole field, for guiding the signal electrons 113 towards the electron detector 140. For example, the second plurality of electrodes can include eight or more electrodes for generating an octupole field. In particular, the multipole field generated by the second plurality of electrodes 146 can be an electrostatic field. According to some embodiments that can be combined with other embodiments described herein, one or more electrodes within the charged particle beam column 120 can be an assembly of at least one of four or eight (or more) electrodes configured to generate a multipole field for guiding signal electrons.

[0058] FIG. 1B further shows an ion source 152 and a gap 153. The ion source 152 generates positive ions, for example, as exemplarily shown in FIG. 1A. The gap 153 allows 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 towards the substrate. A bias can be applied to the first plurality of electrodes 146 and / or the second plurality of electrodes 148 to generate a uniform electric field, particularly on or adjacent to the upper surface of the packaging substrate 10.

[0059] According to one embodiment, an apparatus for non-contact testing of a packaging substrate is provided. The apparatus includes a vacuum chamber 101 and a stage 105 within the vacuum chamber. The stage is configured to support the packaging substrate 10, which is a panel packaging substrate or an advanced packaging substrate. The apparatus further 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 onto the packaging substrate, a scanner configured to scan the electron beam to different positions on the packaging substrate, and an electron detector 140 for detecting signal electrons 113 emitted when the electron beam collides with the packaging substrate. The apparatus 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 towards the substrate. Further, an analysis unit 141 is provided. The analysis unit determines whether the first inter-device electrical interconnection path 20 has a defect based on the signal electrons 113.

[0060] According to some embodiments that can be combined with other embodiments described herein, as shown in FIG. 1B, one or more electrodes can be provided within the charged particle beam column. For example, one or more electrodes can be arranged to induce signal electrons towards the detector. According to some embodiments that can be combined with other embodiments described herein, a gap is provided between the one or more electrodes and the packaging substrate. In particular, the gap can be provided between at least one charged particle beam column and the packaging substrate.

[0061] According to some embodiments that can be combined with other embodiments described herein, the electric fields illustratively shown in FIG. 1A, as well as the electric fields generated by the first plurality of electrodes and / or the second plurality of electrodes, can be made uniform, particularly on the surface of the packaging substrate. The electric field can further be made uniform between the surface of the packaging substrate and one or more electrodes. A uniform electric field within a region is constant at every point within that region. A uniform electric field has the same intensity and the same direction at each point and is compatible with uniformity. That is, all points experience the same physical phenomenon. Thus, a uniform electric field may also be referred to as a homogeneous electric field.

[0062] The first plurality of electrodes and / or the second plurality of electrodes can be utilized to induce signal electrons during the detection of signal electrons and to generate an electric field for charge control. According to additional or alternative variations, an additional electric field may be generated by an additional electrode, such as electrode 154 shown in FIG. 1A, or by a combination of the additional electrode and the first plurality of electrodes and / or the second plurality of electrodes.

[0063] In some embodiments that can be combined with other embodiments described herein, the electron detector 140 includes an Everhard-Thornley detector. As schematically shown in FIG. 1B, an energy filter 142 for signal electrons 113 may be disposed in front of the electron detector 140, particularly in front of the Everhard-Thornley detector. The energy filter may include a grid electrode configured to be set at a predetermined potential. The energy filter 142 may enable suppression of low-energy signal electrons. The energy filter 142 may suppress signal electrons unrelated to the voltage contrast measurement being performed. In some embodiments, the energy filter 142 may suppress signal electrons emitted from uncharged surface areas and allow only signal electrons emitted from charged surface contacts to pass through. Thus, the signal current detected by the electron detector may depend on the energy of the signal electrons indicating whether the surface contact being explored has a defect.

[0064] In some embodiments, the apparatus 100 may include a scan controller 123 connected to the scan deflector 122 of the charged particle beam column 120. The scan deflector 122 may be configured to scan an electron beam over the substrate surface. The electron beam may be directed, for example, with a first beam probe diameter over a portion of the packaging substrate. The portion of the packaging substrate can be the area of the packaging substrate or the entire area of the packaging substrate over which the electron beam is scanned. The electron beam can raster scan over that portion of the packaging substrate. For example, one or more scan deflectors 122 can scan an electron beam over that portion of the packaging substrate. The portion of the packaging substrate may be a surface contact. The electron beam can be vector scanned to one or more surface contacts of the packaging substrate. For example, one or more scan deflectors can be used to perform a wakeher scan of the electron beam to one or more surface contacts.

[0065] For example, the scanning controller 123 may be configured to control the scanning deflector in such a manner that an electron beam is sequentially guided to pairs of a first surface contact and a second surface contact in order to test respective inter-device electrical interconnection paths extending between each pair of the first surface contact and the second surface contact. This enables rapid and reliable inspection of a plurality of electrical interconnection paths extending through the packaging substrate.

[0066] According to some embodiments that can be combined with other embodiments described herein, for charging, the electron beam can be vector scanned to individual locations, such as surface contacts of the packaging substrate, and for detecting signal electrons, the electron beam can be vector scanned to individual locations. Alternatively, for charging, the electron beam can be vector scanned to individual locations, such as surface contacts of the packaging substrate, and for detecting signal electrons, the electron beam can be raster scanned over an area of the packaging substrate. According to some embodiments that can be combined with other embodiments described herein, for charging and for detecting signal electrons, the electron beam of the charged particle beam column can be scanned to one or more locations on the packaging substrate.

[0067] As schematically shown in FIG. 1B, the electron source 121 is connected to a power supply 130. The power supply can provide the electron source with a high voltage for emitting an electron beam, i.e., a primary electron beam. According to some embodiments that can be combined with other embodiments described herein, the voltage provided by the power supply 130 can be changed to vary the energy of the electron beam and thus the incident energy of the electron beam incident on the packaging substrate. According to some embodiments that can be combined with other embodiments described herein, one or more power supplies can be connected to various components of the electron beam column. For example, a power supply can be connected to the electron source (shown in FIG. 1B), the extraction electrode of the electron source, the anode of the electron source, a deceleration electrode configured to decelerate electrons before they collide with the packaging substrate, and / or the stage 105. The incident energy of the electron beam incident on the packaging substrate is determined by the potential difference between the potential of the emitter tip of the electron source and the potential of the packaging substrate or the potential of the stage 105, respectively. Therefore, one or more power supplies can be provided for changing the incident energy of the electron beam.

[0068] According to one embodiment, an apparatus for non-contact testing of a packaging substrate is provided. The packaging substrate is a panel packaging substrate or an advanced packaging substrate. The apparatus includes a vacuum chamber 101 and a stage 105 within the vacuum chamber, and the stage is configured to support a packaging substrate that is a panel packaging substrate or an advanced packaging substrate. The apparatus further includes an electron beam column configured to generate an electron beam, and the electron beam column includes an objective lens 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 for detecting signal electrons emitted when the electron beam collides with the packaging substrate. The apparatus 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 towards the substrate, and further includes one or more electrodes.

[0069] FIG. 1B exemplarily shows a grounded stage 105. The stage may be directly grounded, may be grounded via a DC power supply as exemplarily shown in FIG. 1B, or may be grounded via an AC power supply. According to some embodiments that can be combined with other embodiments described herein, the stage can include a conductive stage surface that is directly or indirectly grounded to provide a reference potential.

[0070] When placing the packaging substrate on the stage 105, the packaging substrate has a defined charge provided thereon. Nevertheless, the stage can be made conductive. Thus, the stage can be provided at a defined potential. For example, the defined potential may be the ground potential, or a negative or positive potential with respect to the ground. For example, a DC power supply can be provided between the ground and the conductive stage. Alternatively, an AC power supply can also be provided between the ground and the conductive stage, in which case a defined alternating potential can be provided. According to some embodiments that can be combined with other embodiments described herein, a non-conductive material is provided on the surface of the stage 105. For example, a dielectric material layer can be provided as the surface of the stage. Having a non-conductive stage surface enables adding charge to the packaging substrate and maintaining it on the packaging substrate for detection during a test operation or a defect review operation.

[0071] According to some embodiments that can be combined with other embodiments described herein, the stage includes a conductive stage surface that is directly or indirectly grounded to provide a reference potential. According to further additional or alternative modifications, the packaging substrate can be partially connected to the ground, for example, the packaging substrate can be partially connected to the ground by the stage. For example, some circuits can be connected to GND, while some circuits are not grounded. According to further additional modifications that can be combined with other embodiments described herein, the packaging substrate can be capacitively connected to the ground, for example, the packaging substrate can be capacitively connected to the ground by the stage. For some embodiments, there is no ohmic connection.

[0072] The defined potential of the stage, particularly the conductive stage, provides electric field lines, particularly to the stage surface and the non-conductive portion of the packaging substrate. The defined potential can be utilized to affect the electron beam of the electron beam column.

[0073] According to additional embodiments that can be combined with other embodiments described herein, capacitive coupling between the packaging substrate and the stage 105 can provide a packaging substrate at a defined potential. For example, capacitive coupling to ground can be provided by a grounded conductive stage 105. In addition or alternatively, a predetermined set of structures on the packaging substrate may be grounded. However, the predetermined set of structures may not need to be charged by grounding and may serve as a reference potential.

[0074] FIG. 1B shows the controller 180. According to some embodiments that can be combined with other embodiments described herein, the controller can be connected to one or more of the components of the apparatus 100 for non-contact testing of the packaging substrate and for charge control. As exemplarily shown in FIG. 1B, the controller can be connected to the power supply 130, the scan controller 123, the analysis unit 141, the ion source 152, and the stage 150. The controller may further be connected to the electron detector 140.

[0075] The controller 180 includes a central processing unit (CPU), a memory, and, for example, support circuits. To facilitate the control of the apparatus for testing the packaging substrate, the CPU may be one of any form of general-purpose computer processor and sub-processor 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 disk, or any other form of digital storage. The support circuits may be coupled to the CPU to support the processor in a conventional manner. These circuits include, for example, cache, power supply, clock circuit, input / output circuit, and related subsystems. Generally, inspection process instructions are stored in the memory as software routines, which are usually known as recipes. The software routines may be further stored and / or executed by a second CPU (not shown) located far from the hardware controlled by the CPU. When executed by the CPU, the software routines convert a general-purpose computer into a special-purpose computer (controller) for controlling the operation of the apparatus, for example, for controlling charge control, incident energy, stage positioning, and / or charged particle beam scanning during a 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 in the present disclosure may be executed within the hardware or by a software controller. Therefore, embodiments of the present invention may be implemented in software executed on a computer system, may be implemented in hardware as an application-specific integrated circuit or other type of hardware implementation, or may be implemented as a combination of software and hardware.

[0076] The controller may execute or perform a method for testing a packaging substrate using an electron beam column. According to some embodiments, the method includes generating ions and generating an electric field for controlling charge using the ions. Further, the method includes testing the packaging substrate, in particular, directing an electron beam of at least one electron beam column onto at least a first portion of the packaging substrate, and testing the packaging substrate by directing an electron beam of at least one electron beam column onto the packaging substrate. The method further includes detecting signal electrons emitted during the collision of the electron beam to test at least one first inter-device electrical interconnection path of the packaging substrate.

[0077] According to one embodiment, an apparatus for testing a packaging substrate using any of the methods described herein is provided. The apparatus may include a controller 180. The controller includes a processor and a memory storing instructions that cause the apparatus to execute a method according to an embodiment of the present disclosure when executed by the processor.

[0078] Figures 2A and 2B show enlarged cross-sectional views of a packaging substrate during the test method described herein. The packaging substrate 10 may be an AP substrate or a PLP substrate for manufacturing a multi-die integrated package, and includes a first die connection interface for 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 exemplarily shown in Figures 2A and 2B) extend between respective first surface contacts of the first die connection interface and respective second surface contacts of the second die interconnection interface. These surface contacts may be formed as solder bumps having three-dimensional shape dimensions, such as solder bumps having an essentially hemispherical shape, or may include solder bumps having three-dimensional shape dimensions, such as solder bumps having an essentially hemispherical shape.

[0079] 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 being tested by guiding a charged electron beam 111 onto the first surface contact 21 and then guiding that 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. Signal electrons 113 emitted from the second surface contact 22 are detected, and the signal electrons 113 contain information regarding 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. Further, in order to know whether there is a short circuit or leakage between different electrical interconnection paths, the detected voltage contrasts of successive measurements of adjacent electrical interconnection paths can be compared.

[0080] After testing the first inter-device electrical interconnection path 20, for example, by scanning (vector scanning) the electron beam to other positions using respective scanning deflectors and / or by moving the stage on which the packaging substrate is supported, the electron beam 111 can be guided onto two surface contacts of a second inter-device electrical interconnection path 23. Using the charged electron beam and the probing electron beam, a plurality of inter-device electrical interconnection paths can be successively tested. Thus, a plurality of test points can be tested sequentially and / or in parallel.

[0081] In FIG. 2B, there is an open circuit 151 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 charging of the first surface contact 21 by the charged electron beam 111.

[0082] In FIG. 2B, there is a short circuit 152 between the second inter-device electrical connection path 23 and the third inter-device electrical connection path 24. The short circuit is determined because the third inter-device electrical connection path 24 is charged together with the second inter-device electrical connection path 23, and this can be detected by a probing electron beam guided onto an additional surface contact 27 of the third inter-device electrical connection path 24 after or during the charging of the second inter-device electrical connection path 23.

[0083] For evaluation and defect classification, the measurement signals of adjacent interconnect paths and / or previously collected data can be compared in such a way that open circuits, short circuits, and leaks in the packaging substrate can be identified.

[0084] FIG. 3 is a schematic top view of the packaging substrate 10 described herein during testing. The packaging substrate has a top surface including a plurality of surface contacts arranged in a two-dimensional pattern. The packaging substrate 10 includes a first die connection interface 31 for 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 additional die connection interfaces that may be arranged in pairs adjacent to each other. The first die connection interface 31 may include a plurality of first surface contacts, for example, 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, for example, a plurality of second surface contacts formed as solder bumps.

[0085] In some embodiments, each first surface contact of the first die connection interface 31 is connected by an inter-device electrical interconnection path to one respective second surface contact of the second die connection interface 32. 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 that can be combined with other embodiments described herein, a first surface contact may be connected to one second surface contact. Alternatively, a first surface contact may be connected to two or more second surface contacts. These two or more second surface contacts can be probed using an electron beam, for example, after a charge has been applied to the first surface contact.

[0086] According to the test method described herein, a charged electron beam 111 is directed, particularly focused, onto the first surface contacts of the first die connection interface 31 and directed, particularly focused, onto the associated second surface contacts of the second die connection interface 32. To test whether there is an "open circuit" defect in the electrical interconnection path connecting the first surface contact and the second surface contact, signal electrons emitted from the second surface contact are detected. Thereafter, the remaining surface contacts of the first and second die connection interfaces may be tested, particularly in pairs.

[0087] Alternatively, or in addition, it can also be tested in a manner such that it can be determined whether the surface contacts of another inter-device electrical interconnection path are charged as a result of the charging of one inter-device electrical interconnection path, for "short circuit" defects, either in parallel or subsequently. For example, an electron beam can be rastered over a portion of the packaging substrate to generate an image of that portion of the packaging substrate. The image can be evaluated, for example, by pattern recognition.

[0088] Figures 4A - 4D show enlarged cross-sectional views of a packaging substrate that can be tested according to the method described herein.

[0089] The packaging substrate 10 shown in FIG. 4A has surface contacts on both main surfaces of the packaging substrate. For example, a plurality of first inter-device electrical interconnection paths may extend between a first surface contact and a second surface contact exposed on the upper surface of the substrate, and a plurality of second inter-device electrical interconnection paths may extend between the first surface contact and the second surface contact exposed on the lower surface of the substrate.

[0090] The packaging substrate 10 shown in FIG. 4B has at least one inter-device electrical interconnection path extending between at least three surface contacts 25, namely a first surface contact, a second surface contact, and at least a third surface contact.

[0091] The packaging substrate 10 shown in FIG. 4C has at least one inter-device electrical interconnection path extending in a complex connection network between at least three surface contacts 25 exposed on different main surfaces of the substrate. Such an inter-device electrical interconnection path may be configured to connect three or more dies to each other through the packaging substrate.

[0092] 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 interconnection path extends through the at least one interconnect bridge 29. In particular, a plurality of inter-device electrical interconnection 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 the manufacture of the packaging substrate. The interconnect bridge may be a bridge chip embedded in the packaging substrate to increase the connection speed between a plurality of dies.

[0093] According to some embodiments that can be combined with other embodiments described herein, the test method and / or apparatus according to the present disclosure may be utilized during and / or after the manufacture of a packaging substrate. For example, tests may be applied to a packaging substrate that does not yet include all layers or structures. For example, tests may be performed after a redistribution layer (RDL) is manufactured and / or after a via layer is manufactured. RDL tests and / or via tests can be provided. Further, tests may be provided for the completed packaging substrate.

[0094] Tests may be provided by charging one or more portions, e.g., surface contacts (writing to the one or more portions) and detecting (reading) charges on the packaging substrate by signal electrons. The number of electrons emitted from the surface of the packaging substrate per incident 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 in comparison 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, i.e., a first neutral energy value and a second neutral energy value, where 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, i.e., signal electrons can be detected, using an electron beam having one of these neutral energy values.

[0095] According to some embodiments that can be combined with other embodiments described herein, directing an electron beam onto a portion of a packaging substrate with a first incident energy can be a charging operation. The charging operation "writes" charge to one electrical interconnect path or a network of electrical interconnect paths. Further, directing an electron beam onto a portion of a packaging substrate with a second incident energy can be an operation of detecting signal electrons. The electron beam with the second incident energy may "read" the charge of one electrical interconnect path or a network of electrical interconnect paths.

[0096] According to some embodiments that can be combined with other embodiments described herein, during the detection of signal electrons, i.e., during the reading of charge, charging of the portion of the packaging substrate is reduced or avoided. In particular, while detecting signal electrons, e.g., while detecting previously provided charge, affecting the charge of the electrical interconnect path or a network of electrical interconnect paths is avoided or minimized.

[0097] For example, assume that a network of electrical interconnect paths includes five (or any number greater than two) surface contacts. Charge can be added to, i.e., "written" to, the first surface contact. At the second surface contact, the charge added to the network of electrical interconnect paths can be "read". It is beneficial not to change the charge of the network of electrical interconnect paths having five surface contacts while "reading" the charge on the second to fifth surface contacts. Thus, by utilizing a neutral energy value for the incident energy, generation of charge can be reduced or avoided while detecting signal electrons.

[0098] The neutral energy value is material-dependent. The material of the packaging substrate or the material on the surface of the packaging substrate is known, and with respect to the method of testing the packaging substrate, the incident energy 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 the packaging substrate. According to some embodiments that can be combined with other embodiments described herein, the incident energy of the test method can be selected to be between the first neutral energy value and the second neutral energy value for charging so as to be higher than the second neutral energy value for charging, or to be smaller than the first neutral energy value. The incident energy can be adapted according to the test strategy, the material of the packaging substrate and / or the material of the surface contact.

[0099] For incident energies lower than the first neutral energy value, negative charging occurs. That is, the total electron yield is less than 1. For incident energies between the first neutral energy value and the second neutral energy value, positive charging occurs. That is, the total electron yield is greater than 1. A total electron yield greater than 1 is related to more electrons leaving the surface compared to the number of electrons colliding with the surface. Therefore, the packaging substrate or structure becomes positively charged. For incident energies greater than the second neutral energy value, negative charging occurs. That is, the total electron yield is less than 1. A total electron yield less than 1 is related to fewer electrons leaving the surface compared to the number of electrons colliding with the surface. The packaging substrate or structure becomes negatively charged.

[0100] According to embodiments of the present disclosure, a test structure, such as an area and / or surface contact of a packaging substrate, can be positively or negatively charged by an electron beam collision. Depending on the primary energy level, i.e., the incident energy, the total electron yield can be controlled with respect to the secondary electron yield. A test point potential can be determined. The voltage contrast principle can be utilized for defect detection. 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 incident energy can be varied to be higher than a second neutral energy value or lower than the second neutral energy value. The incident energy of the electron beam is set to a predetermined incident energy and is disposed on a portion of the packaging substrate, for example, on a surface contact or a test point on the packaging substrate. The electron beam remains on that portion of the packaging substrate for a defined period of time to positively or negatively charge that portion of the packaging substrate with respect to the environment of that portion of the packaging substrate. For example, the environment of the surface contact being tested can be one or more adjacent surface contacts.

[0101] According to one embodiment, a method for testing a packaging substrate using at least one electron beam column is provided. The packaging substrate is a panel level packaging substrate or an advanced packaging substrate. The method includes placing the packaging substrate on a stage within a vacuum chamber, filling 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 positive ions or negative charges towards the substrate, and testing the packaging substrate within the vacuum chamber.

[0102] The packaging substrate described in this specification can be a panel-level packaging substrate or an advanced packaging substrate. As shown in FIG. 5, the method is implemented using an electron beam column and includes placing the packaging substrate on a stage within a vacuum chamber (see operation 501). In operation 502, ions are generated within the vacuum chamber. In particular, positive ions and / or negative charges are generated. The positive ions and / or negative charges may fill at least a portion of the vacuum chamber. In operation 503, an electric field is generated, for example, between electrodes, a first plurality of electrodes 146 and / or a second plurality of electrodes 148 and the packaging substrate. Generating an electric field between one or more electrodes and the packaging substrate accelerates the positive ions or negative charges towards the substrate. The charges are useful for charge control, particularly charge control using a self-alignment process. In operation 504, the packaging substrate is tested within the vacuum chamber.

[0103] To test, at least one electron beam of at least one electron beam column is directed onto at least a first portion of the packaging substrate, and at least one electron beam of at least one electron beam column is directed onto at least a second portion of the packaging substrate. To test a first inter-device electrical interconnection path of the packaging substrate, signal electrons emitted upon collision of at least one electron beam are detected.

[0104] According to some embodiments that can be combined with other embodiments described herein, at least one electron beam can be directed with a first incident energy onto at least a first portion, and onto at least a second portion with a second incident energy different from the first charged incident energy. For example, signal electrons can be detected when at least one electron beam impinges with a second incident energy, for reading charges on a packaging substrate. 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 by less than +-10% from the neutral energy value, and the neutral energy value corresponds to the incident energy at which the total electron yield is 1.

[0105] According to some embodiments that can 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 a packaging substrate and onto at least a second portion of the packaging substrate. According to further additional variations that can be combined with embodiments of the present disclosure, the electron beam is scanned at one or more locations on the packaging substrate for charging and for detecting signal electrons. Additionally or alternatively thereto, the method may include passing the signal electrons through an energy filter.

[0106] Embodiments of the present disclosure can include a method for testing a packaging substrate, as illustrated by the flow diagram shown in FIG. 6. At operation 601, an advanced packaging substrate or panel level packaging substrate can be loaded into a test chamber, such as the vacuum chamber 110 shown in FIG. 1B. At operation 602, the packaging substrate is moved under an electron beam column. An electron beam test or electron beam test sequence may include charging a test point, i.e., a surface contact on the packaging substrate, and reading the test point, i.e., the surface contact on the packaging substrate. Testing the packaging substrate may include directing at least one electron beam of at least one electron beam column onto at least a first portion of the packaging substrate, directing at least one electron beam of at least one electron beam column onto at least a second portion of the packaging substrate, and detecting signal electrons emitted upon collision of at least one electron beam to test a first inter-device electrical interconnect path of the packaging substrate.

[0107] For example, at least one electron beam can be 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. Signal electrons are detected when at least one electron beam collides with the second incident energy to read the charge on the packaging substrate.

[0108] In operation 603, the vacuum chamber or at least a portion of the vacuum chamber, particularly the portion adjacent to the packaging substrate, is filled with ions. Thus, the ions can travel between the packaging substrate and the positive or negative electrode. The electrodes can be the electrodes utilized during the operation of the charged particle beam column. The electric field provided between the substrate and the electrodes accelerates positive ions or negative charges towards the packaging substrate. Particles having opposite charges are attracted by the electrodes, for example, the electrodes or portions of the charged particle beam column. In operation 604, the charge neutralizes the charge on the packaging substrate. The packaging substrate can be set to a defined charge condition. For example, the packaging substrate can be set to a defined potential with respect to the ground. In operation 605, the ion source can be turned off. Further, the electric field can be turned off or the electric field can be changed to a test operation mode. An electron beam test including charging of the contacts and reading of the contacts is provided.

[0109] According to some embodiments that can be combined with other embodiments described herein, operations 603 and 604 may be provided during an electron beam test sequence or between different electron beam test sequences. An intermediate ion discharge step can be provided during the test of the packaging substrate. The charge control described herein provides an improved signal-to-noise ratio for testing the packaging substrate using an electron beam, based on defined start conditions of the contacts or test points, particularly defined start conditions of all contacts or test points. A uniform and integral charge control method for the entire test area can be provided. Further, since the charge control process is self-consistent, a uniformly charged packaging substrate can be provided. Self-consistency is based, inter alia, on the fact that, for example, more negatively charged areas attract more positive ions until equilibrium is reached across the entire packaging substrate. As described above, the test operations according to embodiments of the present disclosure are contactless and can be provided independently of the test feature dimensions and / or topography.

[0110] Figures 7A to 7C show the effect of charge control according to an embodiment of the present disclosure. As shown in Figure 7A, without pre-treatment by ions, the images generated using a charged particle beam column show inferior uniformity and higher noise. Therefore, different electron beam positions on the packaging substrate result in different signal levels. The correlation between the sample potential and the signal electrons measured by voltage contrast is reduced. Figure 7B shows a similar image after pre-treatment. For example, a pressure of about 5×10 -3 Pa to about 1×10 -1 Pa, for example about 5×10 -2 Pa, results in an ion density for beneficial charge control. The SEM images show improved uniformity and lower signal noise. Different electron beam arrangements on the packaging substrate will result in the same signal level. A good correlation between the sample potential and the voltage contrast measurement can be provided. At lower pressures, for example a pressure of about 5×10 -4 Pa, the ion density is lower and such pressures may not result in efficient sample discharge. The image shown in Figure 7C shows little improvement in uniformity or signal-to-noise ratio. Therefore, the embodiments of the present disclosure may result in better defect detectability and more accurate parameter measurements, such as capacitance.

Industrial Applicability

[0111] Embodiments of the present disclosure include electron beam testing, particularly electron beam writing of charges onto a packaging substrate and electron beam reading of charges on a packaging substrate, and in particular provide an electron beam test that generates defined measurement conditions and / or start conditions. According to some embodiments that can be combined with other embodiments described herein, at least one electron beam can be focused while guiding the electron beam over at least a first portion of the packaging substrate and over at least a second portion of the packaging substrate. In addition or alternatively, the electron beam can be scanned to one or more positions on the packaging substrate for charging and for detecting signal electrons.

[0112] Embodiments of the present disclosure provide one or more of the following advantages. A non-contact electrical test of the packaging substrate disclosed herein can be provided, wherein charges can be controlled for electrical defect detection. The 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. A unified and uniform charge control method for the complete test area can be provided. The charge control is self-consistent. During mass production, testing including 100% of the electrical interconnection paths is possible. Further, the flexibility of the electron beam allows testing and flexible settings for different AP / PLP substrate layouts. The test methods and apparatus disclosed herein are independent of the test feature dimensions and further allow scaling to smaller dimensions, particularly when technology development shifts to smaller structure sizes. The test of the packaging substrate does not cause damage.

[0113] The above description is directed to some embodiments, but other and additional embodiments may be devised without departing from the basic scope of the embodiments of the present disclosure, and the scope of the embodiments of the present disclosure is determined by the following claims.

Claims

1. A method for testing a packaging substrate (10) using at least one electron beam column, wherein the packaging substrate is a panel level packaging substrate or an advanced packaging substrate, and the method comprises: placing the packaging substrate (10) on a stage (105) within a vacuum chamber (101); filling 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 towards the substrate; testing the packaging substrate within the vacuum chamber using at least one electron beam column; A method comprising the above.

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

3. The method according to claim 2, wherein the ion source is selected from the group consisting of an ion source including a gas supply source, a VUV source, and a spark for generating the positive ion source.

4. The method according to any one of claims 1 to 3, wherein the electric field is uniform at the surface of the packaging substrate, or the electric field is uniform between the surface of the packaging substrate and the one or more electrodes.

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

7. Testing the packaging substrate comprises: 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; detecting signal electrons emitted upon collision of the at least one electron beam to test a first inter-device electrical interconnection path of the packaging substrate; A method according to any one of claims 1 to 6, comprising the above.

8. The method according to claim 7, wherein at least one of the electron beams is guided with a first incident energy onto at least the first portion and with a second incident energy different from the first incident energy onto at least the second portion.

9. The method according to claim 8, wherein the signal electrons are detected when at least one of the electron beams impinges with the second incident energy for reading charges on the packaging substrate.

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

11. An apparatus (100) for non-contact testing of a packaging substrate (10), comprising a vacuum chamber (101), a stage (105) within the vacuum chamber, the stage (105) being configured to support the packaging substrate which is a panel packaging substrate or an advanced packaging substrate, a charged particle beam column (120) configured to generate an electron beam and comprising: an objective lens (124) 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) for detecting signal electrons (113) emitted when the electron beam impinges on the packaging substrate. The apparatus 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 being configured to accelerate positive ions or negative charges towards the substrate; and an analysis unit (141) for determining whether a first inter-device electrical interconnection path (20) has a defect based on the signal electrons (113).

12. The apparatus according to claim 11, wherein the one or more electrodes are provided within the charged particle beam column.

13. The apparatus according to claim 12, wherein the one or more electrodes are arranged to direct signal electrons towards the detector.

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

15. The stage has a conductive stage surface that is directly or indirectly grounded to provide a reference potential The device according to any one of claims 11 to 14.

16. The electron detector (140) has an energy filter (142) for the signal electrons (113) The device according to any one of claims 11 to 15.

17. A scanning controller (123) configured to sequentially direct the electron beam to the pair of the first surface contact and the second surface contact in order to test each device - to - device electrical interconnection path extending between each pair of the first surface contact and the second surface contact The device according to any one of claims 11 or 16, further comprising.

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