Method and device for detecting surface of interconnection structure

Abstract

The invention discloses a method and device for detecting the surface of an interconnection structure. The interconnection structure comprises a metal layer and a dielectric layer with fluorescent characteristics. The method for detecting the surface of the interconnection structure comprises the following steps: generating an excitation light beam by utilizing an excitation light source, adjusting the excitation light beam to enable the excitation light beam to form an elongated light spot with a long axis and a short axis on the surface of the interconnection structure, and enabling the excitation light forming the elongated light spot to be incident on the surface of the interconnection structure in a direction vertical to the long axis of the elongated light spot, and receiving a plurality of fluorescence signals generated after the dielectric layer is excited by the long light spots, and judging partial plane patterns of the metal layer according to the fluorescence signals.

Description

Technical Field

[0001] This disclosure relates to a method for detecting an interconnect structure, and more particularly to a method for detecting an interconnect structure having a fluorescent component. Background Art

[0002] When manufacturing an integrated circuit, a redistribution layer (RDL) is often provided and used to connect components or conductors at different positions in the integrated circuit through the lines therein. For example, in a wafer-level packaging process, a redistribution layer is often provided on the integrated circuit to connect the input / output terminals with a relatively small distribution range on the integrated circuit to the solder pads or solder balls with a relatively large distribution range on the packaging wafer. Generally, the redistribution layer may include metal layers located on multiple planes, and each metal layer may include multiple metal lines, which are separated by dielectric layers.

[0003] In the manufacturing process, in order to ensure the quality of the redistribution layer, it is necessary to detect the surface metal of the redistribution layer to determine whether there are short circuits, open circuits or deformations. For the convenience of detection, the prior art can add a fluorescent substance to the dielectric layer, and during detection, the distribution of the dielectric layer can be obtained by detecting the fluorescence signal emitted by the dielectric layer, so as to judge the distribution of the metal layer. However, when using the excitation light to excite the dielectric layer to emit fluorescence, since the surface metal layer of the redistribution layer may block the incident of the excitation light on the dielectric layer, the fluorescence signal intensity generated by some dielectric layers is weak, resulting in misjudgment of the distribution of the dielectric layer or the metal layer. Therefore, how to effectively detect the distribution of the surface metal remains a problem to be solved. Summary of the Invention

[0004] An embodiment of this disclosure provides a method for detecting the surface of an interconnect structure. The interconnect structure includes a metal layer and a dielectric layer having fluorescent properties. The method for detecting the surface of the interconnect structure includes: using an excitation light source to generate an excitation beam, adjusting the excitation beam so that the excitation beam forms an elongated light spot having a major axis and a minor axis on the surface of the interconnect structure, and making the excitation light forming the elongated light spot incident on the surface of the interconnect structure in a direction perpendicular to the major axis of the elongated light spot, receiving a plurality of fluorescence signals generated after the dielectric layer is excited by the elongated light spot, and judging a partial planar pattern of the metal layer based on these fluorescence signals.

[0005] Another embodiment of the present disclosure provides a device for detecting the surface of an interconnect structure. The interconnect structure includes a metal layer and a dielectric layer having fluorescence characteristics. The device for detecting the surface of the interconnect structure includes an excitation light source, a light shape adjustment module, a sensor, and a controller. The excitation light source is used to generate an excitation beam. The light shape adjustment module is used to adjust the excitation beam so that the excitation beam forms an elongated light spot with a major axis and a minor axis on the surface of the interconnect structure, and the excitation light forming the elongated light spot is incident on the surface of the interconnect structure in a direction perpendicular to the major axis of the elongated light spot. The sensor is used to receive a plurality of fluorescence signals generated after the dielectric layer is excited by the elongated light spot. The controller is used to determine a partial planar pattern of the metal layer based on these fluorescence signals.

[0006] Brief Description of the Drawings

[0007] Figure 1 is a partial top view of an interconnect structure according to an embodiment of the present disclosure;

[0008] Figure 2 is Figure 1 a sectional view of the surface structure of the interconnect structure;

[0009] Figure 3 is Figure 1 a schematic diagram of the situation of irradiating an excitation light on the interconnect structure;

[0010] Figure 4 is Figure 3 a schematic imaging diagram of receiving fluorescence signals emitted by the dielectric layer under the irradiation situation;

[0011] Figure 5 is a flowchart of the steps of a method for detecting the surface of an object according to an embodiment of the present disclosure;

[0012] Figure 6 is Figure 5 using the Figure 1 method to detect the

[0013] Figure 7 is Figure 5 using the Figure 1 method to irradiate an excitation light on the interconnect structure;

[0014] Figure 8 is Figure 7 a schematic imaging diagram of receiving fluorescence signals emitted by the dielectric layer under the irradiation situation;

[0015] Figure 9 is Figure 5 using the Figure 1 method to irradiate an excitation light on the interconnect structure in another schematic diagram of the situation;

[0016] Figure 10 isFigure 9 Schematic diagram of the incident angle of the excitation light of the elongated light spot;

[0017] Figure 11 is based on Figure 5 The method is used to Figure 1 Another schematic diagram of irradiating the excitation light to the interconnect structure;

[0018] Figure 12 is Figure 11 Schematic diagram of the incident angle of the excitation light of the elongated light spot;

[0019] Figure 13 Schematic diagram of the device for detecting the surface of the interconnect structure according to an embodiment of the present disclosure;

[0020] Figure 14 and Figure 15 Schematic diagram of adjusting the light shape by using the first lens and the objective lens according to an embodiment of the present disclosure;

[0021] Figure 16 and Figure 17 Schematic diagram of adjusting the light shape by using the first lens and the objective lens according to another embodiment of the present disclosure. Detailed implementation manners

[0022] This application claims the priority and benefits of the Taiwan, China application No. 112151178 filed on December 27, 2023. The content of the Taiwan, China application and the official case are incorporated herein by reference in their entirety.

[0023] Figure 1 is a partial top view of the interconnect structure E1 according to an embodiment of the present disclosure, Figure 2 is a cross-sectional view of the surface structure of the interconnect structure E1 cut along the tangent line AA'. The interconnect structure E1 of the present disclosure includes, but is not limited to, a printed circuit board, a semiconductor carrier (substrate or carrier), an interposer, a semiconductor wafer, or a redistribution layer (RDL) of a package, or other structures providing laminated wiring. As Figure 1 and Figure 2 shown, the surface structure of the interconnect structure E1 includes a metal layer MT1 and a dielectric layer IL1. The metal layer MT1 includes a plurality of lines, such as lines 11, 12, 13, 14, 15, and 16. The dielectric layer IL1 surrounds the metal layer MT1 and can be used to separate these lines 11, 12, 13, 14, 15, and 16 of the metal layer MT1. In some embodiments, other circuit structures may be further included below the surface structure of the interconnect structure E1, such as a plurality of metal layers disposed on different planes and a plurality of dielectric layers for separating different metal layers (not shown in Figure 2 ).

[0024] In this embodiment, in order to detect the planar pattern of the metal layer MT1 located on the surface of the interconnect structure E1, the dielectric layer IL1 can be made to have fluorescence characteristics. In this case, by irradiating the surface of the interconnect structure E1 with excitation light, the fluorescent substance in the dielectric layer IL1 can be excited to emit fluorescence, and the distribution of the dielectric layer IL1 can be obtained by sensing the fluorescence signal, thereby judging the planar pattern of the metal layer MT1.

[0025] Figure 3 is a schematic diagram of the situation of irradiating the interconnect structure E1 with excitation light, Figure 4 is in Figure 3 the irradiation situation, the imaging diagram obtained by receiving the fluorescence signal emitted by the dielectric layer IL1. In Figure 3 , the excitation light L1 irradiates the surface of the interconnect structure E1 in a relatively large size range, and the traveling direction of the excitation light L1 towards the surface of the interconnect structure E1 in the XZ plane shows a converging state, that is, the excitation light L1 incident on the left side of the line 13 (i.e., the side where the component on the X-axis gradually decreases) is incident from the left side, and the excitation light L1 incident on the right side of the line 14 (i.e., the side where the component on the X-axis gradually increases) is incident from the right side. In this case, since the excitation light L1 will be blocked by the lines 11, 12, 13, 14, 15 and 16 on the path of entering the dielectric layer IL1, the dielectric layer IL1 cannot be uniformly illuminated. For example, the part of the dielectric layer IL1 on the right side of the line 11 and the right side of the line 12 will only receive relatively weak excitation light L1 due to being blocked by the lines 11 and 12, and the part of the dielectric layer IL1 on the left side of the line 15 and the left side of the line 16 will only receive relatively weak excitation light L1 due to being blocked by the lines 15 and 16.

[0026] As Figure 4 shown, after irradiating the excitation light L1, the metal lines 11, 12, 13, 14, 15 and 16 do not emit fluorescence because they do not have fluorescence characteristics and are represented by black blocks. In contrast, between the metal lines 11, 12, 13, 14, 15 and 16, the part of the dielectric layer IL1 that receives sufficient excitation light L1 will emit a relatively strong fluorescence signal and is represented by a white block. Since there is a significant difference in the fluorescence signal intensity received by the white block and the black block, it can be more clearly judged that the black block corresponds to the metal layer MT1 and the white block corresponds to the dielectric layer IL1.

[0027] However, the dielectric layer IL1 on the right side of the lines 11 and 12 and the left side of the lines 15 and 16 can only emit relatively weak fluorescence because it does not receive sufficient excitation light stimulation, so it is represented by a shaded block. In this case, since the difference in the fluorescence signal intensity received by the shaded block and the black block is small, it is more difficult to judge whether the shaded block corresponds to the metal layer MT1 or the dielectric layer IL1, and thus misjudgment is likely to occur.

[0028] In this embodiment, the surface of the metal layer MT1 is lower than the surface of the dielectric layer IL1. However, the present disclosure is not limited thereto. In some embodiments, the surface of the metal layer MT1 may also be higher than the surface of the dielectric layer IL1, or the surface of the metal layer MT1 may be flush with the surface of the dielectric layer IL1. In this case, the shielding effect of the metal layer MT1 on the dielectric layer IL1 will be more obvious.

[0029] In addition, with the progress of the manufacturing process, the line width of the metal layer MT1 is increasingly reduced, resulting in more frequent misjudgment. As Figure 1 shown, some of the lines 11, 12, 13, 14, 15, and 16 of the metal layer MT1 extend along the Y direction. In some embodiments, the line width WW1 in the X direction of these portions of the lines 11, 12, 13, 14, 15, and 16 extending along the Y direction may be less than or equal to 20 micrometers (as Figure 1 shown), or the line width WW1 / line pitch may be less than or equal to 20 micrometers / 20 micrometers (the line pitch is not shown). In this case, according to the Figure 3 usage scenario shown, the excitation light may be severely shielded by the sidewalls of the lines 11, 12, 13, 14, 15, and 16, resulting in no obvious fluorescence intensity difference at the junction of the dielectric layer IL1 and the metal layer MT1, and the line boundary of the metal layer MT1 cannot be accurately judged, that is, the problem of blurred boundary occurs. Especially when using a scanning system with a large field of view to detect a metal layer with a small line width, the above-mentioned metal sidewall shielding effect is more serious.

[0030] In order to enable the dielectric layer IL1 between the lines 11, 12, 13, 14, 15, and 16 to receive the excitation light more uniformly to avoid misjudgment, in some embodiments, the angle of incidence of the excitation beam on the interconnect structure E1 can be adjusted to reduce the situation where the excitation light is shielded by the lines 11, 12, 13, 14, 15, and 16.

[0031] Figure 5 FIG. is a flowchart of the steps of a method M1 for detecting the surface of an object according to an embodiment of the present disclosure. The method M1 may include steps S110 to S140 and can be applied to detect the surface of the interconnect structure E1. Figure 6 FIG. is a schematic diagram of the scenario of using the method M1 to detect the interconnect structure E1.

[0032] In step S110, an excitation light source can generate an excitation beam. In step S120, the excitation beam can be adjusted so that the excitation beam forms an elongated light spot SPT1 with a major axis and a minor axis on the surface of the interconnect structure E1, as Figure 6 shown. In this case, the surface of the interconnect structure E1 within the range of the elongated light spot SPT1 will receive the excitation light.

[0033] In some embodiments, the major axis LE1 of the elongated light spot SPT1 can be, for example but not limited to, the axis having the longest distance in the main extension direction of the elongated light spot SPT1 in the elongated light spot SPT1; and the minor axis SE1 of the elongated light spot SPT1 can be, for example but not limited to, the axis having the longest distance in the secondary extension direction of the elongated light spot SPT1 in the elongated light spot SPT1. As Figure 6 shown, the major axis LE1 of the elongated light spot SPT1 can extend along the first direction (e.g., the X direction), and the minor axis SE1 of the elongated light spot SPT1 can extend along the second direction (e.g., the Y direction). In this embodiment, the elongated light spot SPT1 can be, for example, a long and narrow rectangle, the length of its major axis LE is equivalent to the length of the long side of the rectangle, and the length of its minor axis SE1 is equivalent to the length of the short side of the rectangle, and the first direction is perpendicular to the second direction. However, the present disclosure is not limited thereto. In some embodiments, the elongated light spot SPT1 may also be, for example but not limited to, a polygon or an ellipse, and it may have at least one of the following features: having rounded corners, having uneven long sides and / or short sides, having concave long sides and / or short sides, or having convex long sides and / or short sides. In addition, the major axis LE1 and the minor axis SE1 of the elongated light spot SPT1 may also not be perpendicular to each other.

[0034] In certain embodiments, the major axis LE1 of the elongated light spot SPT1 can be at least more than five times the length of the minor axis SE1 of the elongated light spot SPT1, for example ten times, to facilitate large Field of View scanning, reduce the number of scan lines, and shorten the detection time. For example, the major axis LE1 of the elongated light spot SPT1 can be, for example but not limited to, more than 3 mm, and the minor axis SE1 of the elongated light spot SPT1 can be, for example but not limited to, from 100 microns to 300 microns. However, the present disclosure is not limited thereto.

[0035] Since the surface of the interconnect structure E1 can be irradiated in a manner of a larger size range through the elongated light spot SPT1 in the extension direction of its major axis LE1 (which is also the first direction or the X direction in this embodiment), the elongated light spot SPT1 will be able to irradiate the lines 11, 12, 13, 14, 15, and 16 arranged along the first direction and the dielectric layer between the lines 11, 12, 13, 14, 15, and 16. In this case, when adjusting the light shape of the excitation beam in step S120, the excitation light forming the elongated light spot SPT1 can further be incident on the surface of the interconnect structure E1 in a direction perpendicular to the major axis LE1 of the elongated light spot SPT1.

[0036] Figure 7 is a schematic diagram of the situation of irradiating the interconnect structure E1 with the excitation light L2 according to the method M1, Figure 8 is in Figure 7An imaging diagram obtained by receiving the fluorescence signal emitted by the receiving dielectric layer IL1 under the irradiation scenario. In this embodiment, Figure 7 is Figure 6 observed by a cross-sectional view obtained by cutting the interconnect structure E1 with the median tangent AA'.

[0037] As Figure 7 shown, since the excitation light L2 in the elongated light spot SPT1 is incident on the surface of the interconnect structure E1 in a manner perpendicular to the long axis LE1 of the elongated light spot SPT1, the situation where the excitation light L2 is blocked by the lines 11, 12, 13, 14, 15, and 16 in the traveling direction can be reduced, so that the dielectric layer IL1 between the lines 11, 12, 13, 14, 15, and 16 can uniformly receive the excitation light. In this case, as Figure 8 shown, since the dielectric layer IL1 between the lines 11, 12, 13, 14, 15, and 16 can all receive the excitation light, a fluorescence signal with sufficient intensity can be correspondingly generated. In this way, in step S130, the fluorescence signal generated after the dielectric layer IL1 is excited by the elongated light spot SPT1 can be received, and in step S140, the planar pattern of the corresponding part of the metal layer MT1 can be determined based on the received fluorescence signal.

[0038] In some embodiments, a line scanner can be used in step S130 to receive the fluorescence signal generated after the dielectric layer IL1 is excited by the elongated light spot SPT1. In addition, the interconnect structure E1 can be placed on a crawler or a movable tool, so that the interconnect structure E1 can gradually move along the extension direction of the short axis SE1 of the elongated light spot SPT1 (i.e., the second direction or the Y direction). In this way, the entire surface of the interconnect structure E1 can be gradually scanned by the elongated light spot SPT1, thereby obtaining the complete planar pattern of the metal layer MT1 of the interconnect structure E1. In some embodiments, the interconnect structure E1 can be irradiated in the manner of step S120 when the long axis LE1 of the elongated light spot SPT1 is parallel or perpendicular to some lines of the metal layer MT1, however, the present disclosure is not limited thereto.

[0039] In addition, since the elongated light spot SPT1 irradiates the surface of the interconnect structure E1 in a manner with a relatively small size range in the extension direction of the short axis SE1 (which is also the second direction or the Y direction in this embodiment), the object that the elongated light spot SPT1 can irradiate on the short axis SE1 is relatively limited, and it is less likely to occur the situation where the light is blocked by the metal lines. In this case, when adjusting the light shape of the excitation beam in step S120, the excitation light L2 forming the elongated light spot SPT1 can also be converged on an incident surface including the short axis SE1, that is, the multiple rays forming the elongated light spot SPT1 have an included angle in the traveling direction towards the surface of the interconnect structure E1. In this way, the intensity of the excitation light irradiating the interconnect structure E1 can be increased within the range of the elongated light spot SPT1.

[0040] Figure 9 Another schematic diagram of the excitation light irradiating the interconnect structure E1 according to the method M1 Figure 10 is Figure 9 a schematic diagram of the incident angle of the excitation light L2 of the elongated light spot SPT1. In this embodiment, Figure 9 it is Figure 6 observed with the cross-sectional view obtained by cutting the interconnect structure E1 with the tangent line BB'. As Figure 9 and Figure 10 shown, the excitation light L2 in the elongated light spot SPT1 is perpendicular to the extension direction of the long axis LE1 (i.e., the first direction or the X direction), and converges on an incident plane containing the short axis SE1. That is, the multiple light rays forming the elongated light spot SPT1 have an angle θ1 in the traveling direction towards the surface of the interconnect structure E1. In this case, the excitation light L2 can converge a higher energy within a smaller range, so that the dielectric layer IL1 within the irradiation range of the elongated light spot SPT1 can be more effectively excited by the excitation light L2 to emit fluorescence.

[0041] However, the present disclosure does not limit that the excitation light in the elongated light spot SPT1 needs to converge on an incident plane containing the short axis SE1. In some embodiments, in step S120, the excitation light forming the elongated light spot SPT1 can also be perpendicular to the extension direction of the short axis SE. Figure 11 Another schematic diagram of the excitation light irradiating the interconnect structure E1 according to the method M1. In Figure 11 this case, in step S120, the excitation light beam can be adjusted into an elongated light spot SPT1', and the excitation light L2' forming the elongated light spot SPT1' is perpendicular to the extension direction of the short axis SE.

[0042] Figure 11 it is Figure 6 observed with the cross-sectional view obtained by cutting the interconnect structure E1 with the tangent line BB' to observe the irradiation situation of the excitation light L2', and Figure 12 is Figure 11 a schematic diagram of the incident angle of the excitation light L2' of the elongated light spot SPT1'. As Figure 11 and Figure 12 shown, the excitation light L2' in the elongated light spot SPT1' can be perpendicular to the extension directions of both the long axis LE1 and the short axis SE1 at the same time. That is to say, the excitation light L2' of the elongated light spot SPT1' irradiates the surface of the interconnect structure E1 in a nearly collimated manner. In this case, regardless of whether the lines in the metal layer MT1 are arranged along the first direction or the second direction, the nearly collimated excitation light of the elongated light spot SPT1' will not be blocked by the lines and can be incident on the dielectric layer IL1.

[0043] Since the method M1 of the present disclosure can adjust the excitation beam into an elongated light spot SPT1 (or SPT1') to irradiate the interconnect structure E1, and can make the excitation light L2 (or L2') in the elongated light spot SPT1 or SPT1' incident in a direction perpendicular to the long axis LE1 of the elongated light spot SPT1 (or SPT1'), it is possible to reduce the situation where the excitation light is blocked by the metal layer in the extending direction of the long axis LE1 irradiated in a large size range, so that the dielectric layer IL1 can receive the excitation light more uniformly, thereby increasing the range of the planar pattern of the metal layer MT1 that can be effectively judged each time.

[0044] Figure 13 FIG. 4 is a schematic diagram of a device 100 for detecting the surface of an interconnect structure according to an embodiment of the present disclosure. The device 100 may include an excitation light source 110, a light shape adjustment module 120, a sensor 130, and a controller 140. In some embodiments, the device 100 may perform the steps in the method M1 to obtain the planar pattern of the metal layer MT1.

[0045] For example, the excitation light source 110 can be used to perform step S110 to generate an excitation beam LB1, and the light shape adjustment module 120 can be used to perform step S120 to adjust the optical path and light shape of the excitation beam LB1, so that the excitation beam LB1 forms an elongated light spot SPT1 on the surface of the interconnect structure E1, and makes the excitation light forming the elongated light spot SPT1 incident on the surface of the interconnect structure E1 in a direction perpendicular to the long axis LE1 of the elongated light spot SPT1. Then, the sensor 130 can perform step S130 to receive the fluorescence signal emitted after the dielectric layer IL1 is excited. In some embodiments, the sensor 130 can be, for example, a line scanner and can have the characteristic of time delay integration (TDI). In addition, in some embodiments, the sensor 130 can also use a back-illuminated high-sensitivity sensor or a area array scanner. The sensor 130 may include photosensitive elements, such as charge-coupled devices (CCDs) or complementary metal oxide semiconductor active pixel sensors (CMOS Active pixel sensors). In some embodiments, the sensor 130 can convert the intensity of the fluorescence signal into a corresponding electrical signal, and the controller 140 can judge the planar pattern of the corresponding part of the metal layer MT1 according to the electrical signal representing the intensity of the fluorescence signal in step S140.

[0046] As Figure 13As shown, the light shaping module 120 may include a light collimating system 121, a beam splitter 122, an objective lens 123, a first lens 124, a first filter 125, a second filter 126, and a second lens 127. In some embodiments, the light collimating system 121 may shape the excitation beam LB1 into a nearly collimated beam CLB1 (for example, but not limited to, with a divergence angle within 10°). The first lens 124 is disposed in the downstream optical path of the light collimating system 121 and may further adjust the optical path of the nearly collimated beam CLB1. The beam splitter 122 may reflect the excitation light passing through the first lens 124, and the objective lens 123 is disposed in the downstream optical path of the first lens and may shape the excitation light reflected by the beam splitter 122 into an elongated light spot SPT1 to be incident on the interconnect structure E1. In other words, by selecting the respective focal lengths of the first lens 124 and the objective lens 123, the nearly collimated beam CLB1 can be further shaped into an elongated light spot SPT1. In this embodiment, the mirror surface of the beam splitter 122 may form an angle of 45° with the optical axis of the first lens 124, and the optical axis of the first lens 124 may be perpendicular to the optical axis of the objective lens 123.

[0047] Figure 14 and Figure 15 FIG. is a schematic diagram of adjusting the light shape using the first lens 124 and the objective lens 123 according to an embodiment of the present disclosure, in which the adjustment of the optical path by the beam splitter 122 is omitted. As Figure 14 shown, the first lens 124 may be, for example, a semi-cylindrical lens, and the objective lens 123 may further converge the excitation light passing through the first lens 124 into an elongated light spot SPT1.

[0048] In some embodiments, the cross-section of the nearly collimated beam CLB1 may have a major axis LE2 and a minor axis SE2. For example, in the Figure 14 and Figure 15 embodiment, the cross-section of the nearly collimated beam CLB1 may be rectangular, and the length of the major axis LE2 of the cross-section of the nearly collimated beam CLB1 is equivalent to the length of the long side of the rectangle, and the length of the minor axis SE2 of the cross-section of the nearly collimated beam CLB1 is equivalent to the length of the short side of the rectangle. However, the present disclosure does not limit the cross-section of the nearly collimated beam CLB1 to be rectangular. In some embodiments, the cross-section of the nearly collimated beam CLB1 may be, for example, but not limited to, a polygon or an ellipse, and it may have at least one of the following features: having rounded corners, having uneven long sides and / or short sides, having concave long sides and / or short sides, or having convex long sides and / or short sides.

[0049] In addition, the length of the major axis LE1 of the elongated light spot SPT1 may be the product of the length of the major axis LE2 of the cross-section of the nearly collimated beam CLB1, the reciprocal of the focal length F1 of the first lens 124, and the focal length F2 of the objective lens 123, that is, as shown in Equation (1).

[0050]

[0051] Furthermore, in some embodiments, the length of the short axis SE1 of the elongated light spot SPT1 may be related to the length of the short axis SE2 of the cross-section of the near-collimated light beam CLB1 and the focal length F2 of the objective lens 123, as shown in, for example, Equation (2).

[0052]

[0053] In Equation (2), M2 represents the beam quality factor of the near-collimated light beam CLB1 (related to the beam divergence angle), and λ represents the wavelength of the excitation light.

[0054] In Figure 14 and Figure 15 embodiments, after being adjusted by the light shape adjustment module 120, the excitation light L2 that forms the elongated light spot SPT1 converges on the incident surface including the short axis SE1 of the elongated light spot SPT1. That is, multiple excitation lights that form the elongated light spot SPT1 have an included angle in the traveling direction towards the surface of the interconnect structure E1 (as shown in Figure 9 and Figure 10 ). However, the present disclosure is not limited thereto. In some embodiments, the light shape adjustment module 120 can also make the excitation light of the elongated light spot perpendicular to the short axis of the elongated light spot.

[0055] Figure 16 and Figure 17 are another schematic diagram of adjusting the light shape using the first lens 124' and the objective lens 123' in an embodiment of the present disclosure, where the adjustment of the light path by the beam splitter 122 is omitted. In some embodiments, the first lens 124' can be used in the light shape adjustment module 120 to replace the first lens 124, and the objective lens 123' can be used in the light shape adjustment module 120 to replace the objective lens 123. As shown in Figure 16 , both the first lens 124' and the objective lens 123' can be convex lenses, such as single convex lenses, double convex lenses, or other lenses with a focusing effect. The first lens 124' and the objective lens 123' can adjust the near-collimated light beam CLB1 output by the light shaping system 121 into an elongated light spot SPT1' having a long axis LE1' and a short axis SE1', and the excitation light that forms the elongated light spot SPT1' will be perpendicular to both the extending direction of the long axis LE1' and the extending direction of the short axis SE1' of the elongated light spot SPT1' (as shown in Figure 11 and Figure 12As shown. In this embodiment, the length of the major axis LE1' of the elongated light spot SPT1' can be the product of the length of the major axis LE2 of the cross-section of the near-collimated beam CLB1, the reciprocal of the focal length F1' of the first lens 124', and the focal length F2' of the objective lens 123', as shown in Equation (3). Similarly, the length of the minor axis SE1' of the elongated light spot SPT1' can be the product of the length of the minor axis SE2 of the cross-section of the near-collimated beam CLB1, the reciprocal of the focal length F1' of the first lens 124', and the focal length F2' of the objective lens 123', as shown in Equation (4).

[0056]

[0057] After being irradiated by the elongated light spot SPT1 (or SPT1'), the dielectric layer IL1 will be excited to emit a fluorescence signal. In some embodiments, the fluorescence signal emitted by the dielectric layer IL1 can be guided by the objective lens 123 and incident on the beam splitter 122. In some embodiments, the beam splitter 122 can be, for example, a dichroic mirror or a semi-reflective mirror. In this case, the beam splitter 122 can reflect the excitation light L2 with a shorter wavelength and allow the fluorescence signal FL1 with a longer wavelength to pass through. In this way, the outgoing light path of the excitation light and the incoming light path of the fluorescence signal can be separated from each other.

[0058] In addition, a first filter 125 and a second filter 126 are also provided in the light shape adjustment module 120. The first filter 125 can be disposed on the light output path of the excitation light, for example, between the light shaping system 121 and the first lens 124, and it can allow the excitation light with wavelengths within a specific range to pass through. Conversely, the second filter 126 can be disposed on the light receiving path of the fluorescence signal and can allow the fluorescence signal passing through the beam splitter 122 to pass through. In some embodiments, the light shape adjustment module 120 can allow the user to replace the second filter 126. That is, when detecting different objects, since different objects (such as dielectric layers of different interconnect structures) may emit fluorescence in different wavelength bands, the corresponding filter can be used as the second filter 126 according to the wavelength band of the fluorescence emitted by the object. For example, if the fluorescence wavelength emitted by the first object to be detected is 600 nm - 700 nm, a filter that allows light with wavelengths in the range of 600 nm - 700 nm to pass through can be placed on the lens holder (not shown in the figure) of the light shape adjustment module 120 as the second filter 126; when changing to detect the second object to be detected, if the fluorescence wavelength emitted by the second object to be detected is 500 nm - 600 nm, the originally set filter can be replaced, and a filter that allows light with wavelengths in the range of 500 nm - 600 nm to pass through can be placed on the lens holder of the light shape adjustment module 120 as the second filter 126. In addition, according to the fluorescence characteristics of the object to be detected, the excitation light source band can be changed by replacing the filter 125 or synchronously replacing the light source 110 to optimize the excitation efficiency of the dielectric layer. For example, if the fluorescence band of the object to be detected is 600 nm - 700 nm, excitation light of 500 nm - 550 nm can be allowed, and when the second object to be detected is 500 nm - 600 nm, excitation light of 400 nm - 450 nm can be allowed to pass through.

[0059] In some embodiments, the light shape adjustment module 120 may further include a second lens 127. The second lens 127 can be disposed on the light receiving path of the fluorescence signal, for example, between the second filter 126 and the sensor 130, and the optical axis of the second lens 127 can coincide with the optical axis of the objective lens 123. The second lens 127 can guide the fluorescence signal FL1 passing through the second filter 126 to the sensor 130. In this way, the sensor 130 can sense the fluorescence signal emitted by the dielectric layer IL1 and can convert the fluorescence signal into a corresponding electrical signal for the controller 140 to determine the regions corresponding to the metal layer MT1 and the dielectric layer IL1, thereby obtaining the planar pattern of the metal layer MT1.

[0060] In summary, the method and apparatus for detecting the surface of an interconnect structure provided by the embodiments of the present disclosure can adjust the excitation beam into an elongated light spot to irradiate the interconnect structure, and can make the excitation light in the elongated light spot incident in a direction perpendicular to the long axis of the elongated light spot. Therefore, in the long-axis extension direction of the large-range irradiation, the situation where the excitation light is blocked by the metal layer can be reduced, so that the dielectric layer can receive the excitation light more evenly, thereby increasing the range that can effectively determine the planar pattern of the metal layer each time.

[0061] Symbol Description

[0062] 11, 12, 13, 14, 15, 16: Circuit

[0063] 110: Excitation light source

[0064] 120: Light shape adjustment module

[0065] 121: Light collimation system

[0066] 122: Beam splitter

[0067] 123, 123': Objective lens

[0068] 124, 124': First lens

[0069] 125: First filter

[0070] 126: Second filter

[0071] 127: Second lens

[0072] 130: Sensor

[0073] 140: Controller

[0074] CLB1: Near-collimated light beam

[0075] E1: Interconnect structure

[0076] IL1: Dielectric layer

[0077] L1, L2, L2': Excitation light

[0078] LB1: Excitation beam

[0079] LE1, LE1': Long axis of the elongated light spot

[0080] LE2: Long axis of the cross-section of the near-collimated light beam

[0081] M1: Method

[0082] MT1: Metal layer

[0083] S110 to S140: Steps

[0084] SE1, SE1': Minor axis of the elongated light spot

[0085] SE2: Minor axis of the cross-section of the near-collimated light beam

[0086] SPT1, SPT1': Elongated light spot

[0087] WW1: Line width

[0088] θ1: Included angle

Claims

1. A method for detecting the surface of an interconnect structure, characterized in that: Include: Using an excitation light source to generate an excitation light beam; Adjusting the excitation light beam so that the excitation light beam forms an elongated light spot having a long axis and a short axis on a surface of the interconnect structure, and making the excitation light forming the elongated light spot incident on the surface of the interconnect structure in a direction perpendicular to the long axis of the elongated light spot, wherein the interconnect structure comprises a metal layer and a dielectric layer having a fluorescent property; receiving a plurality of fluorescence signals generated by the dielectric layer after being excited by the elongated light spot; and A portion of the planar pattern of the metal layer is determined according to the fluorescent signals.

2. The method of claim 1 , wherein the step of adjusting the excitation light beam so that the excitation light beam forms the elongated light spot having the major axis and the minor axis on the surface of the interconnect structure comprises: The exciting light forming the elongated light spot is perpendicular to an extending direction of the short axis.

3. The method of claim 1 , wherein the step of adjusting the excitation light beam so that the excitation light beam forms the elongated light spot having the major axis and the minor axis on the surface of the interconnect structure comprises: The excitation light forming the elongated light spot has an angle in a traveling direction toward the surface of the interconnection structure on an incident surface including the short axis. The method of claim 1 , wherein the major axis is perpendicular to the minor axis. 5 . The method of claim 1 , wherein a length of the major axis of the elongated light spot is at least five times a length of the minor axis of the elongated light spot.

6. The method of claim 1, wherein the metal layer comprises a circuit having a line width less than or equal to 20 micrometers. 7 . The method of claim 1 , wherein the step of receiving a plurality of fluorescent signals generated after the dielectric layer is excited by the elongated light spot comprises using a line scanner to receive the fluorescent signals. 8 . The method according to claim 1 , further comprising scanning the entire surface of the interconnect structure along an extension of the short axis using the elongated light spot to obtain a complete planar pattern of the metal layer.

9. A device for detecting the surface of an interconnect structure, characterized in that: Include: An excitation light source for generating an excitation light beam; a light shape adjustment module, used for adjusting the excitation light beam so that the excitation light beam forms an elongated light spot having a long axis and a short axis on a surface of the interconnection structure, and making the excitation light forming the elongated light spot incident on the surface of the interconnection structure in a direction perpendicular to the long axis of the elongated light spot, wherein the interconnection structure comprises a metal layer and a dielectric layer having a fluorescent property; a sensor for receiving a plurality of fluorescent signals generated after the dielectric layer is excited by the elongated light spot; and A controller is used to determine a portion of the planar pattern of the metal layer according to the fluorescent signals. 10 . The device as claimed in claim 9 , wherein the light shape adjustment module is further used to make the excitation light forming the elongated light spot perpendicular to an extension direction of the short axis. 11 . The device as claimed in claim 9 , wherein the light shape adjustment module is further used to make the excitation light forming the elongated light spot have an angle in a direction of travel from an incident surface including the short axis toward the surface of the interconnection structure. 12 . The device of claim 9 , wherein the length of the major axis of the elongated light spot is at least five times the length of the minor axis of the elongated light spot.

13. The device of claim 9, wherein the metal layer comprises a circuit having a line width less than or equal to 20 micrometers.

14. The apparatus of claim 9, wherein the sensor comprises a line scanner. 15 . The device as claimed in claim 9 , wherein the light shape adjustment module comprises a light shaping system for shaping the excitation light beam into a nearly collimated light beam, and a cross section of the nearly collimated light beam is rectangular.

16. The device as claimed in claim 15, wherein the light shape adjustment module further comprises: a first lens disposed in the downstream optical path of the light-correcting system; and An objective lens is arranged in the downstream optical path of the first lens, and the nearly collimated light beam is further shaped into the elongated light spot by the first lens and the objective lens to be incident on the surface of the interconnection structure. 17 . The device as claimed in claim 16 , wherein the light shape adjustment module further comprises a first filter disposed between the light shaping system and the first lens, for allowing the excitation light with a wavelength within a specific range to pass through. The device as claimed in claim 16 , wherein the first lens is a lens with a light-condensing effect.

19. The device of claim 16, further comprising: A second filter is disposed between the interconnection structure and the sensor to allow the fluorescent signals generated after the dielectric layer is excited by the elongated light spot to pass through.

20. The device of claim 16, wherein the length of the major axis of the elongated light spot is the product of the length of a major axis of a cross section of the nearly collimated light beam, an inverse of a focal length of the first lens, and a focal length of the objective lens.

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