INSPECTION TOOL AND INSPECTION METHOD

An optical inspection tool may include at least a first image capture unit and a second image capture unit for inspecting specimens having a substantially V-shaped grooves. The first image capture unit may be arranged in a first orientation so as to be directable towards a first angular surface of the V-shaped groove of each specimen. The second image capture unit may be arranged in a second orientation so as to be directable towards a second angular surface of the V-shaped groove of each specimen. The first image capture unit may be configured to capture images of defects and/or contamination on the first angular surface and the second image capture unit may be configured to capture images of defects and/or contamination on the second angular surface.

TECHNICAL FIELD

Various aspects of the present disclosure generally relate an inspection tool and an inspection method for inspection of a multifaceted channel or groove of a specimen (e.g., workpiece, substrate etc.), and particularly to an inspection tool and an inspection method for inspection of slope-sided grooves or grooved-shaped features or substantially V-shaped grooves in photonics integrated chips (e.g., semiconductor substrates).

BACKGROUND

Butt optical coupling of laser beam(s), which may be generated from silicon photonics chips, coupled to optical fibers placed or fixed on precisely (in other words, high-precision) manufactured slope-sided grooves or V-shaped grooves is a popular approach in the industry (e.g., semiconductor industry). Such V-shaped grooves may be formed or manufactured using processes, such as thin film coating and anisotropic etching, for example, within CMOS semiconductor fabs. A slope of the sidewall(s) of such V-shaped grooves may be defined by the silicon crystal orientation (e.g., of a semiconductor substrate on which the groove(s) may be formed), while an opening/width of the V-shaped grooves may be controlled by a photolithographic mask size. Optical fibers can be guided passively by such V-shaped grooves to be aligned with waveguides/spot size converter (e.g., in photonic chip(s)). However, due to small or tight permissible alignment tolerance (e.g., ˜2 μm), care needs to be taken during formation and/or handling of such V-shaped grooves. Foreign materials (e.g., contaminants) in such V-shaped grooves and/or imperfectly etched V-shaped grooves can displace the optical fibers which may, in turn, lead to misalignment between optical fibers and the corresponding waveguides (to which the optical fibers are intended to be aligned with), thereby resulting in low optical coupling efficiency.

Conventional inspection systems and inspection methods are inefficient or slow to conduct and are thus not suitable for high rate or high throughput inspection of V-shaped grooves on semiconductor substrates.

Accordingly, there is a need for an improved inspection tool and inspection method which solve at least the above issue.

DETAILED DESCRIPTION

Aspects described below in context of the apparatus are analogously valid for the respective method, and vice versa. Furthermore, it will be understood that the aspects described below may be combined, for example, a part of one aspect may be combined with a part of another aspects.

It should be understood that the terms “on”, “over”, “top”, “bottom”, “down”, “side”, “back”, “left”, “right”, “front”, “lateral”, “side”, “up”, “down”, etc., when used in the following description are used for convenience and to aid understanding of relative positions or directions, and not intended to limit the orientation of any device, or structure or any part of any device or structure. In addition, the singular terms “a”, “an”, and “the” include plural references unless context clearly indicates otherwise. Similarly, the word “or” is intended to include “and” unless the context clearly indicates otherwise.

Various aspects generally relate to a multi-vision (e.g., triple-vision) inspection tool or system that may be capable of simultaneously inspecting (i) at least two sidewalls (e.g., angular surfaces) of a V-groove or a substantially V-shaped groove of a specimen and/or (ii) bottom plateau (e.g., floor surface) of the V-groove or substantially V-shaped groove of the specimen and/or (iii) a top surface of the specimen. The inspection tool or system may be used for inspection and/or sorting, at a wafer level of a semiconductor process line, at a singulated die level of the semiconductor process line, and/or at a package level of the semiconductor process line.

In other words, a multi-vision (e.g., double-vision, triple-vision, quadruple-vision etc.) system or inspection tool, which may be capable of simultaneously inspecting or capturing images of a plurality or all surfaces of a V-groove or a substantially V-shaped groove of a specimen may be provided. In particular, three vision systems (e.g., three image capture units) of the multi-vision system or inspection tool may be oriented (e.g., to be perpendicular to each surface of a substantially V-shaped groove of a specimen under inspection) respectively or individually or independently. In addition, each image capture unit of the inspection tool may have very high optical resolution such that the inspection tool may be capable of detecting sub-micrometer foreign materials (e.g., along the substantially V-shaped groove of the specimen).

Accordingly, various aspects may provide an inspection tool (e.g., an optical inspection tool) as well as a specimen for inspection by the inspection tool. The specimen may include a multifaceted channel or groove (in other words, a channel or groove which may be defined by multiple surfaces, e.g., planar surfaces or inner surfaces of the specimen).

The inspection tool according to various aspects may include a plurality of image capture units (e.g., cameras, sensors, 2-dimensional cameras or sensors, 3-dimensional cameras or sensors, 3-dimensional profilers, triangulation sensors, chromatic confocal 3-dimensional profilers, or laser confocal 3-dimensional profilers, etc.) which may be equal to a number of angular surfaces of the channel or groove (e.g., angular or non-parallel with respect to the base surface of the specimen), or may include a number of image capture units equal (e.g., exactly equal) to a total number of facets or surfaces of the channel or groove. Each image capture unit of the inspection tool according to various aspects may be “optimized” to focus or be focused to only one surface (e.g., unique surface) of the multifaceted channel or groove. In another aspect, at least one image capture unit may be “optimized” to focus or be focused to more than one (e.g., two) surfaces (e.g., parallel surfaces).

Various aspects may also provide an inspection method involving the multi-vision (e.g., double-vision, triple-vision, quadruple-vision etc.) system or inspection tool to inspect a specimen. The inspection method according to various aspects may be non-destructive to the specimen under inspection and may not involve or require any contact (e.g., physical or direct contact) between the specimen and the inspection tool. The inspection method may also be performed swiftly. For instance, with the inspection method according to various aspects, all inner surfaces of a specimen defining or forming a V-groove or substantially V-shaped groove of the specimen may be inspected (e.g., have images thereof captured), simultaneously or instantaneously using the inspection tool. In an aspect, the inspection method may be completed within a fraction of second.

Additionally, the inspection method can be implemented at any one or more stage(s) of a process line (e.g., manufacturing line, semiconductor process line, etc.). Accordingly, within a semiconductor process line, the inspection method can be applied or easily conducted at a wafer level, die level, and/or package level of the process.

FIG.1shows a schematic side view of an inspection tool100and a specimen150for inspection using the inspection tool100, according to various aspects of the present disclosure.

According to an aspect of the present disclosure, the specimen150may be, for example, a workpiece (e.g., metallic workpiece which may be or which may have already been worked on with a tool or a machine, or a metallic part of a ship or vehicle), a substrate (e.g., semiconductor substrate, silicon substrate etc.), a wafer, an electronic circuit board etc., or any other suitable type of specimen for inspection using the inspection tool100.

For ease of illustration, various aspects of the disclosure may be described herein with reference to the specimen150being a semiconductor substrate. Nevertheless, it is understood that the inspection tool100as well as inspection method (described later with reference toFIG.4), as disclosed herein, according to various aspects of the present disclosure, may be applicable to or may extended to other types of specimens, for example, a workpiece (e.g., small-sized metallic workpiece, or large-sized workpiece which may be part of a ship or vehicle).

As shown inFIG.1, the specimen150may include a base surface151(e.g., base) and a top surface152opposite the base surface151. The base surface151may be a bottom of the specimen150configured to abut or contact or rest on an external surface or platform170on which the specimen150may also be placed on for inspection by the inspection tool100. The top surface152of the specimen150may be an upper surface of the specimen150, opposite the base surface151. According to an aspect of the present disclosure, the specimen150may further include at least one or a plurality of side surfaces153aand/or153bextending between the base surface151and the top surface152. Accordingly, the specimen150may be shaped as a block or may have a block-like shape, or a non-block-like shape.

According to an aspect of the present disclosure, the specimen150may include a first channel140for receiving an object therein or therewithin. As shown, the first channel140may be positioned in the top surface152. The first channel140may extend into the specimen150from the top surface152(e.g., downwards, or towards the base surface151). Further, the first channel140may run along the top surface152of the specimen150. Specifically, in an aspect, the first channel140may be extending (or running) along the top surface152of the specimen150in a first direction (e.g., a horizontal/lateral direction, e.g., with respect to the base surface151of the specimen150or the external surface170on which the specimen150may be placed), between a first longitudinal end (e.g., first side surface153a) of the specimen150and a second longitudinal end opposite the first longitudinal end (e.g., second side surface153bopposite the first side surface153a) of the specimen150.

According to an aspect of the present disclosure, the first channel140may be a groove. The first channel140(e.g., groove) may be a multifaceted groove defined or formed by two or more inner surfaces (e.g., planar or substantially planar inner surfaces) of the specimen150.

According to an aspect of the present disclosure, the first channel140may be defined or formed by at least two (e.g., two or more than two) angular surfaces141aand141bof the specimen150. Specifically, the at least two angular surfaces141aand141bmay be angular inner surfaces of the specimen150(e.g., opposite outer surfaces, e.g., side surfaces153aand153bof the specimen150). The at least two angular surfaces141aand141bmay be non-parallel (in other words, may be inclined) with respect to the base surface151(e.g., a substantially planar or flat base surface151) of the specimen150. Specifically, the at least two angular surfaces141aand141bmay be declining from the top surface152. In other words, the at least two angular surfaces141aand141bmay be non-horizontal surfaces and/or may be inclined surfaces with respect to the external surface170on which the specimen150may be placed. The at least two angular surfaces141aand141bmay be disparate and/or different surfaces of the specimen150which define the first channel140of the specimen150. Hence, the at least two angular surfaces141aand141bmay be oriented (e.g., with respect to the base surface151of the specimen150and/or the external surface170on which the specimen150may be placed) in a different orientation from one another.

In an aspect, the at least two angular surfaces141aand141bof the specimen150defining the first channel140may be connected to or abutting each other, for instance, at a bottom or a trough of the first channel140.

In another aspect, the first channel140may further be defined or formed by a floor surface143of the specimen150. Specifically, the floor surface143may be an inner floor surface143of the specimen150defining the first channel140, and/or may be a bottom surface of the first channel140(e.g., opposite the outer base surface151of the specimen150). The floor surface143may be positioned or arranged between the at least two angular surfaces141. For example, the at least two angular surfaces141aand141bmay be adjoined to and may extend (e.g., upwardly, e.g., perpendicularly or non-perpendicularly) from the floor surface143of the specimen150(e.g., towards or to an opening of the channel at or on the top surface152of the specimen150). In an aspect, the floor surface143may be parallel (e.g., substantially parallel) with the base surface151of the specimen150. In another aspect, the floor surface143may be non-parallel with the base surface151of the specimen150. Accordingly, according to an aspect of the present disclosure, the first channel140may include or may have a shape of a truncated (e.g., half of an) octagon (e.g., regular or irregular octagon), a truncated nonagon (e.g., regular or irregular octagon), a truncated decagon (e.g., regular or irregular octagon) etc.

According to an aspect of the present disclosure, the first channel140may be formed by an etching process applied on or to the top surface152of the specimen150. Hence, when the specimen150is a semiconductor substrate or a silicon substrate, an etching process may be applied on or to the top surface152of the semiconductor substrate or silicon substrate to form the first channel140.

Specifically, according to an aspect of the present disclosure, the first channel140may (e.g., through an etching process) be formed as a substantially V-shaped groove or V-like groove (herein collectively or interchangeably referred to as “V-groove”) on the specimen150(e.g., semiconductor substrate). Such a V-groove (e.g., on a semiconductor substrate or a silicon substrate) may guide and support an optical fiber (i.e. the object) and may serve to align an optical fiber core of the optical fiber (i.e. the object) to a corresponding waveguide (e.g., in a silicon photonic chip (PICs)).

According to an aspect of the present disclosure, a first angular surface141aof the at least two angular surfaces141aand141bof the specimen150defining the first channel140(e.g., V-groove) may be opposing (e.g., substantially opposing) a second angular surface141bof the at least two angular surfaces141aand141bof the specimen150defining the first channel140. Further, each of the first angular surface141aand the second angular surface141bof the first channel140(e.g., V-groove) may form an angle (e.g., opposing angle) of between substantially 50 degrees to substantially 60 degrees with respect to the base surface151of the specimen150and/or with respect to the external surface170(e.g., when the specimen150is placed thereon). Specifically, each of the first angular surface141aand the second angular surface141bof the first channel140(e.g., V-groove) may form an angle (e.g., opposing angle) of approximately or substantially 54 to substantially 55 degrees (e.g., 54 0.74 degrees) with respect to the base surface151of the specimen150and/or with respect to the external surface170(e.g., when the specimen150is placed thereon). Thus, for example when the first angular surface141aand the second angular surface141bof the first channel140are substantially symmetrical about a central axis or plane of the first channel140, the first angular surface141aand the second angular surface141bof the first channel140may form an angle (e.g., opposing angle) of between substantially 60 degrees to substantially 80 degrees with respect to one another, or more specifically, between substantially 70 degrees to substantially 72 degrees (e.g., 70.52 degrees) with respect to one another.

According to an aspect of the present disclosure, an opening on the top surface152of the specimen150for providing access to the first channel140(i.e. the opening of the first channel140e.g., V-groove) may have a width (e.g., measured laterally) within a range of approximately 100 μm to 200 μm (e.g., 160 μm). In another aspect, the first channel may have a shortest width of not more than or less than 200 μm. Nevertheless, the width of the opening of the first channel140is not limited as such. For example, according to various other aspects, the width of the opening of the first channel140may be larger than 200 μm.

According to an aspect of the present disclosure, the specimen150may further include at least one (e.g., one or more) secondary channel(s) (e.g., further channel(s)) (not shown inFIG.1; described in detail later with reference toFIG.3). Each secondary channel may be similar or identical to the first channel140. That is, each secondary channel may have a similar or an identical dimension, size, shape, form etc., as the first channel. Accordingly, each secondary channel may be positioned in and may extend along the top surface152of the specimen150, in a same (e.g., identical or similar) direction (i.e. the first direction) as the first channel140. Further, the secondary channel may be positioned adjacent or besides or in a side-by-side arrangement with the first channel140.

With reference toFIG.1, the inspection tool100may include (e.g., further include) a support frame180configured to or for securing or affixing or supporting the inspection tool100to or on the external surface170. According to an aspect of the present disclosure, the inspection tool100may (e.g., optionally) include a support platform for supporting the specimen150thereon. According to an aspect of the present disclosure, the support platform may be included in or may be the external surface170.

According to an aspect of the present disclosure, the inspection tool100may be an optical inspection tool100. The inspection tool100(e.g., optical inspection tool100) may include at least a first image capture unit110and a second image capture unit120respectively configured to or may be for inspecting the specimen150(e.g., a V-groove of the specimen150).

According to an aspect of the present disclosure, the inspection tool100(e.g., optical inspection tool100) may include (e.g., further include) a third image capture unit130configured to or for inspecting the specimen150(e.g., V-groove of the specimen150).

In an aspect, each or all image capture unit(s)110and/or120and/or130of the inspection tool100may be or may include a camera, sensor, 2-dimensional camera or sensor, 3-dimensional camera or sensor, 3-dimensional profiler, triangulation sensor, chromatic confocal 3-dimensional profiler, or laser confocal 3-dimensional profiler, etc.

The first image capture unit110may be arranged in a first orientation (e.g., with respect to the base surface151of the specimen150and/or with respect to the support frame180of the inspection tool100) and/or may be directable so as to face or be directed towards the first angular surface141aof the first channel140or a first secondary angular surface of the secondary channel (e.g., V-groove(s)) (not shown inFIG.1) of the specimen150. In other words, the first image capture unit110when arranged in the first orientation may be directable towards the first angular surface141aof the first channel140or the first secondary angular surface of the secondary channel (not shown inFIG.1). In particular, according to an aspect of the present disclosure, the first image capture unit110may be arranged in the first orientation with respect to the support frame180of the inspection tool100, such that when the inspection tool100is secured to the external surface170and the specimen150is placed on the external surface170, the first image capture unit110may be directed towards the first angular surface141aof the first channel140or the first secondary angular surface of the secondary channel (not shown inFIG.1). Accordingly, the first image capture unit110may be configured to capture image(s) of (e.g., of defects and/or contamination on) the first angular surface141aor first secondary angular surface (not shown inFIG.1).

The second image capture unit120may be arranged in a second orientation (e.g., with respect to the base surface151of the specimen150and/or with respect to the support frame180of the inspection tool100) and/or may be directable so as to face or be directed towards the second angular surface141bof the first channel140or a second secondary angular surface of the secondary channel (e.g., V-groove(s)) (not shown inFIG.1) of the specimen150. Hence, the second orientation may differ from the first orientation (e.g., with respect to the base surface151of the specimen150and/or with respect to the support frame180of the inspection tool100). In particular, according to an aspect of the present disclosure, the second image capture unit120may be arranged in the second orientation with respect to the support frame180of the inspection tool100, such that when the inspection tool100is secured to the external surface170and the specimen150is placed on the external surface170, the second image capture unit120may be directed towards the second angular surface141bof the first channel140or the second secondary angular surface of the secondary channel. Accordingly, the second image capture unit120may be configured to capture image(s) of (e.g., of defects and/or contamination on) the second angular surface141bor second secondary angular surface.

The third image capture unit130may be arranged in a third orientation (e.g., with respect to the base surface151of the specimen150and/or with respect to the support frame180of the inspection tool100) and/or may be directable so as to face or be directed towards the floor surface143of the first channel140or a secondary floor surface of the secondary channel (e.g., V-groove(s)) (not shown inFIG.1). Hence, the third orientation may differ from the first orientation and the second orientation. In particular, according to an aspect of the present disclosure, the third image capture unit130may be arranged in the third orientation with respect to the support frame180of the inspection tool100, such that when the inspection tool100is secured to the external surface170and the specimen150is placed on the external surface170, the third image capture unit130may be directed towards the floor surface143of the first channel140or the secondary floor surface of the secondary channel. Accordingly, the third image capture unit130may be configured to capture image(s) of (e.g., of defects and/or contamination on) the floor surface143or secondary floor surface.

The inspection tool100may (e.g., optionally) include (e.g., further include) a processor88. The processor88may be coupled to at least the first image capture unit110and the second image capture unit120and may optionally be further coupled to the third image capture unit130. Hence, the processor may be configured to analyse the captured images by the first image capture unit110and the second image capture unit120and by the third image capture unit130(e.g., when the processor is also coupled to the third image capture unit130).

Any defects and/or contamination along the first channel140or secondary channel (not shown inFIG.1) may be identified, for example, by comparing the captured image(s) (e.g., by the first image capture unit110, second image capture unit120, third image capture unit130etc.) against ideal image(s) (e.g., of an ideal angular surface, ideal secondary angular surface, ideal floor surface, ideal secondary floor surface etc., which, for example, may be stored in a memory of the processor88or fed to the processor88or provided to a human operator) to identify “differences” (e.g., using the processor88, or manually using sight of the human operator) between the captured image(s) (e.g., by the first image capture unit110, second image capture unit120, third image capture unit130etc.) and the ideal image(s) as potential defects and/or contamination. For example, defects such as lateral translation misalignment (or lateral misalignment) may be identified by comparing a captured image of a respective surface defining the first channel140or secondary channel against an ideal image of the corresponding surface, and any lateral deviation of the captured image from the ideal image may be identified as a lateral translation misalignment. On the other hand, contamination (e.g., contaminants or external particles) may be identified as a dark (or darker) spot or dot (see ref50inFIG.7C) within a captured image of the respective surface defining the first channel140or secondary channel.

According to an aspect of the present disclosure, each of the first image capture unit110and/or the second image capture unit120and/or the third image capture unit130may be “optimized”, that is, may be configured to be “focused” on or to (e.g., to only) a surface defining the first channel140or the secondary channel that the said image capture unit is directed towards or is facing such that the said image capture unit is capable or is configured to capture a focused or sharp (e.g., substantially sharp) image of (e.g., of only) the said surface.

According to an aspect of the present disclosure, one or more or all of the first image capture unit110and/or the second image capture unit120and/or the third image capture unit130may have a numerical aperture of 0.95 (e.g., substantially 0.95), or a numerical aperture of less than 0.95. For example, each of the first image capture unit110and the second image capture unit120may have a numerical aperture of less than 0.95, while the third image capture unit130may have a numerical aperture of 0.95 (in other words, the numerical aperture of the third image capture unit130may be larger/higher in value than the numerical apertures of the first image capture unit110and the second image capture unit120). As another example, all of the first image capture unit110, the second image capture unit120, and the third image capture unit130may have a same (e.g., identical or similar) numerical aperture (e.g., either 0.95 or of a value less than 0.95).

According to an aspect of the present disclosure, any one or more or all of the first image capture unit110, the second image capture unit120, and/or the third image capture unit130may be configured with a pixel resolution of substantially 500 nm.

Further, any one or more or all of the first image capture unit110, the second image capture unit120, and/or the third image capture unit130may be configured with a field of view of substantially 3.5 mm by 5 mm

Further, any one or more or all of the first image capture unit110, the second image capture unit120, and/or the third image capture unit130may be configured with a depth of field of substantially 30 μm.

According to an aspect of the present disclosure, all image capture units (e.g., the first image capture unit110, the second image capture unit120, the third image capture unit130etc.) of the inspection tool100may be identical to each other. That is, according to an aspect of the present disclosure, all image capture units (e.g., the first image capture unit110, the second image capture unit120, the third image capture unit130etc.) of the inspection tool100may have a same “image capture” setting and/or configuration and/or may be of a same type of image capture unit (e.g., microscope, digital camera, camera, sensor, 2-dimensional camera or sensor, 3-dimensional camera or sensor, 3-dimensional profiler, triangulation sensor, chromatic confocal 3-dimensional profiler, or laser confocal 3-dimensional profiler etc.).

According to an aspect of the present disclosure, the inspection tool100may be part of an inspection system (not shown). In other words, an inspection system (not shown) may include the inspection tool100as described herein. The inspection system may further include a first station (e.g., corresponding to a wafer level of a semiconductor process line). The inspection system may further include a second station (e.g., corresponding to a die level of the semiconductor process line). The inspection system may further include a third station (e.g., corresponding to a package level of the semiconductor process line). The second station may be downstream of the first station, and the third station may be downstream of the second station. Each station may include at least one inspection tool100(e.g., secured to a corresponding external surface or platform170at the station for placing the specimen150thereon). Hence, when the inspection system includes three stations, the inspection system may include three inspection tools100(i.e. one inspection tool100for each station).

In an aspect, the inspection system may include (e.g., further include) the specimen150.

In an aspect, the inspection system may include (e.g., further include) a conveyor (not shown) configured to or for moving the specimen150between stations (e.g., from the first station to the second station and/or from the second station to the third station), such that at each station, the conveyor positions the specimen150(e.g., on a corresponding external surface or platform170disposed at that station) in a manner such that each image capture unit of the inspection tool100at that station is directed to face a distinct and/or only one inner surface (e.g., angular surface or floor surface) of a channel (e.g., first channel140or secondary channel) of the specimen150. Further, at each station, the conveyor may also be configured to move the specimen150(e.g., with respect to the station), in a manner (e.g., lateral or sideway manner, relative to direction of the conveyor from one station to another station) such that the inspection tool100at that station may be capable of capturing image(s) of any secondary channel(s) of the specimen150after capturing image(s) of the first channel140, for example, without having to move the inspection tool100itself.

According to an aspect of the present disclosure, the inspection system (as described) may be positioned or disposed within in an atmospherically-controlled chamber or room, and further, the specimen150(or a plurality of specimens150) may be conveyed (e.g., by the conveyor) to the inspection system for inspection by the inspection tool100of the inspection system within the atmospherically-controlled chamber or room.

FIG.2Ashows a schematic front view of an inspection tool200and a specimen250which includes a substantially V-shaped groove240, according to various aspects of the present disclosure.

According to an aspect of the present disclosure, the inspection tool200ofFIG.2Amay contain any one or more or all the features and/or limitations of the inspection tool100ofFIG.1. In the following, the inspection tool200is described with like reference characters generally referring to the same or corresponding parts/features of the inspection tool100ofFIG.1. The description of the parts/features made with respect to inspection tool200may also be applicable with respect to inspection tool100, and vice versa.

Further, according to an aspect of the present disclosure, the specimen250ofFIG.2Amay contain any one or more or all the features and/or limitations of the specimen150ofFIG.1. In the following, the specimen250is described with like reference characters generally referring to the same or corresponding parts/features of the specimen150ofFIG.1. The description of the parts/features made with respect to specimen250may also be applicable with respect to specimen150, and vice versa.

As in the inspection tool100ofFIG.1, the inspection tool200ofFIG.2Amay include a first image capture unit210, a second image capture unit220, and a third image capture unit230.

As in the specimen150ofFIG.1, the specimen250ofFIG.2Amay include a first channel240. As shown, the first channel240may be a substantially V-shaped groove defined or formed by a floor surface (i.e. inner floor surface)243as well as a first angular surface (i.e. angular inner surface)241aand a second angular surface241bextending from the floor surface243towards or to an opening of the first channel240at a top surface252of the specimen250.

The first channel240of the specimen250may be dimensioned to and/or may be sized to receive or fit an optical fiber (e.g., an object) therein or therewithin and/or at least partially grip or sandwich or hold the optical fiber. Accordingly, each of the first angular surface241aand the second angular surface241bof the first channel240of the specimen250may form an angle (e.g., opposing angle) of between substantially 50 degrees to substantially 60 degrees with respect to a base surface251of the specimen250. Specifically, each of the first angular surface241aand the second angular surface241bof the first channel240may form an angle (e.g., opposing angle) of approximately or substantially 54 to substantially 55 degrees (e.g., 54 0.74 degrees) with respect to the base surface251of the specimen250. Hence, according to an aspect of the present disclosure, for example when the first angular surface241aand the second angular surface241bare substantially symmetrical about a central axis or plane of the first channel240, the first angular surface241aand the second angular surface241bof the first channel240may form an angle (e.g., opposing angle) of between substantially 60 degrees to substantially 80 degrees with respect to one another, or more specifically, between substantially 70 degrees to substantially 72 degrees with respect to one another (e.g., 70.52 degrees) with respect to one another, for receiving (e.g., at least partially receiving and/or holding) the optical fiber therebetween. According to an aspect of the present disclosure, the opening on the top surface252of the specimen250for providing access to the first channel240may have a width (e.g., measured laterally) or a shortest width equal (e.g., substantially equal) to or larger than a largest width of the optical fiber.

FIG.2Bshows a close-up schematic front view of surfaces of the specimen250ofFIG.2Awhich define the substantially V-shaped groove240with respect to corresponding orientations or directions of the image capture units210,220and230of the inspection tool250ofFIG.2A, according to various aspects of the present disclosure.

With reference toFIG.2AandFIG.2B, the first image capture unit210may be configured in a first orientation or direction (as shown by arrow11) to face or be directed to the first angular surface241aof the first channel240. In particular, an optical axis of the first image capture unit210(e.g., optical axis of a lens, camera, sensor etc. of the first image capture unit210) may be perpendicular (e.g., substantially perpendicular) to the first angular surface241a. The first image capture unit210may be configured to be focused to (e.g., to only) the first angular surface241aso as to capture an image (e.g., sharp image) of (e.g., only of) the first angular surface241a.

The second image capture unit220may be configured in a second orientation or direction (as shown by arrow12), which may be different from the first orientation, to face or be directed to the second angular surface241bof the first channel240. In particular, an optical axis of the second image capture unit220(e.g., optical axis of a lens, camera, sensor etc. of the second image capture unit220) may be perpendicular (e.g., substantially perpendicular) to the second angular surface241b. The second image capture unit220may be configured to be focused to (e.g., to only) the second angular surface241bso as to capture an image (e.g., sharp image) of (e.g., only of) the second angular surface241b.

The third image capture unit230may be configured in a third orientation or direction (as shown by arrow13), which may be different from the first orientation and the second orientation, to face or be directed to the floor surface243of the first channel240. In particular, an optical axis of the third image capture unit230(e.g., optical axis of a lens, camera, sensor etc. of the third image capture unit230) may be perpendicular (e.g., substantially perpendicular) to the floor surface243. In an aspect, the third image capture unit230may be configured to be focused to (e.g., to only) the floor surface243so as to capture an image (e.g., sharp image) of (e.g., only of) the floor surface243. In another aspect, the floor surface243may be parallel (e.g., substantially parallel) with the top surface252of the specimen250, and the third image capture unit230may be configured to be focused (e.g., substantially focused) to both the floor surface243and the top surface252of the specimen250(e.g., simultaneously, or alternatively, in sequence) so as to be capable of capturing an image (e.g., a substantially sharp or focused image) of both the floor surface243and the top surface252of the specimen250.

FIG.3shows a schematic front view of the inspection tool200ofFIG.2Aand a specimen350which includes a secondary channel345for inspection by the inspection tool200, according to various aspects of the present disclosure.

As shown, the specimen350may include a first channel340. The first channel340of the specimen350may be similar or identical to the first channel140of the specimen150ofFIG.1or the first channel240of the specimen250ofFIG.2A.

As shown, according to an aspect of the present disclosure, the specimen350may further include at least one (e.g., one or more) secondary channel(s)345(e.g., further channel(s)). Each secondary channel345may be similar or identical to the first channel340. That is, each secondary channel345may have a similar or an identical dimension, size, shape, form etc., as the first channel340.

Accordingly, the secondary channel345may be positioned in and may extend along a top surface352of the specimen350, in a same (e.g., identical or similar) direction (i.e. the first direction) as the first channel340. Further, the secondary channel345may be positioned adjacent or besides the first channel340. In other words, the first channel340as well as the secondary channel345(e.g., at least one or more or all secondary channel(s)345) may be in a side-by-side arrangement with respect to one another, on or along the top surface352of the specimen350. The secondary channel345may be defined or formed by at least two secondary (e.g., at least two other) angular surfaces (i.e. angular inner surfaces)346aand346bof the specimen350. As shown, the at least two secondary angular surfaces346aand346bdefining the secondary channel345may be non-parallel (i.e. inclined) with a base surface351of the specimen350. Further, the at least two secondary angular surfaces346aand346bmay be oriented with respect to the base surface351of the specimen350in a different orientation from one another.

In an aspect, the secondary channel345may further be defined or formed by a secondary floor surface348of the specimen350. The secondary floor surface348may be positioned or arranged between the at least two secondary angular surfaces346aand346bdefining the secondary channel345. For example, the at least two secondary angular surfaces346aand346bmay be adjoined to and may extend (e.g., upwardly, e.g., perpendicularly or non-perpendicularly) from the secondary floor surface348of the specimen350defining the secondary channel345(e.g., towards or to an opening of the channel at or on the top surface352). In an aspect, the secondary floor surface348may be parallel (e.g., substantially parallel) with the base surface351(e.g., substantially planar or flat base surface351) of the specimen350. In another aspect, the secondary floor surface348may be non-parallel with the base surface351of the specimen350. Accordingly, according to an aspect of the present disclosure, the secondary channel345may include or may have a shape of a truncated octagon (e.g., regular or irregular octagon), a truncated nonagon (e.g., regular or irregular octagon), a truncated decagon (e.g., regular or irregular octagon) etc.

In another aspect (not shown), the at least two secondary angular surfaces346aand346bdefining the secondary channel345may be connected to or abutting each other, for instance, at a bottom or a trough of the secondary channel345.

According to an aspect of the present disclosure, the secondary channel345may be formed by an etching process applied on or to the top surface352of the specimen350(e.g., a semiconductor substrate or a silicon substrate).

Specifically, according to an aspect of the present disclosure, the secondary channel345may (e.g., through an etching process) be formed as a substantially V-shaped groove or V-like groove (i.e. “V-groove”) on the specimen350(e.g., semiconductor substrate or silicon substrate).

Accordingly, a first secondary angular surface346aof the specimen350defining the secondary channel345(e.g., V-groove) may be opposing (e.g., substantially opposing) a second secondary angular surface346bof the specimen350defining the secondary channel345. Further, each of the first secondary angular surface346aand the second secondary angular surface346bdefining the secondary channel345(e.g., V-groove) may form an angle (e.g., opposing angle) of between substantially 50 degrees to substantially 60 degrees with respect to the base surface351of the specimen350and/or with respect to the external surface170(e.g., when the specimen350is placed thereon). Specifically, each of the first secondary angular surface346aand the second secondary angular surface346bdefining the secondary channel345(e.g., V-groove) may form an angle (e.g., opposing angle) of approximately or substantially 54 to substantially 55 degrees (e.g., 54 0.74 degrees) with respect to the base surface351of the specimen350and/or with respect to the external surface170(e.g., when the specimen350is placed thereon). Thus, for example when the first secondary angular surface346aand the second secondary angular surface346bare substantially symmetrical about a central axis or plane of the secondary channel345, the first secondary angular surface346aand the second secondary angular surface346bdefining the secondary channel345may form an angle (e.g., opposing angle) of between substantially 60 degrees to substantially 80 degrees with respect to one another, or more specifically, between substantially 70 degrees to substantially 72 degrees (e.g., 70.52 degrees) with respect to one another.

To inspect the first channel340(e.g., a longitudinal segment of or the entire first channel340) using the inspection tool200, the specimen350may be moved in the first direction (e.g., in a same direction in which the first channel340is extending along), with respect the inspection tool200, or vice versa (in other words, the inspection tool200may be moved relative to the specimen350), while the image capture units210,220and230of the inspection tool200are facing or directed towards the first channel340.

To inspect the secondary channel345, for example, after inspecting the first channel340, the specimen350may be moved (e.g., in a second direction substantially perpendicular to the first direction), relative to the inspection tool200, or vice versa (in other words, the inspection tool200may be moved relative to the specimen350), such that (i) the first image capture unit210of the inspection tool200may face or be directed towards the first secondary angular surface346aof the secondary channel345, (ii) the second image capture unit220of the inspection tool200may face or be directed towards the second secondary angular surface346bof the secondary channel345, and/or (iii) the third image capture unit230of the inspection tool200may face or be directed towards the secondary floor surface348of the secondary channel345.

FIG.4depicts an inspection method400, according to various aspects of the present disclosure.

With reference toFIG.1,FIG.2A,FIG.2BandFIG.3, the inspection method400, which may include or involve the inspection tool100or200and/or the specimen150,250or350, may be described.

According to an aspect of the present disclosure, the method400may include a step401of providing the specimen150,250or350(e.g., semiconductor substrate) for inspection. The specimen150,250or350may include the base surface151or251, the top surface152or252opposite the base surface151or251, and the first channel140,240or340positioned in the top surface152or252in the first direction for receiving an object therein. The first channel140,240or340may be formed by at least two angular surfaces141aand141bor241aand241bof the specimen150,250or350. The at least two angular surfaces141aand141bor241aand241bmay be inclined with the base surface151or251of the specimen150,250or350. Further, at least two angular surfaces141aand141bor241aand241bmay be oriented with respect to the base surface151or251in a different orientation from one another.

According to an aspect of the present disclosure, the method400may include (e.g., further include) a step402providing the inspection tool100or200to inspect the specimen150,250or350. The inspection tool100or200may include (i) the first image capture unit110or210oriented or configured to face a first angular surface141aor241aof the at least two angular surfaces141aand141bor241aand241band (ii) the second image capture unit120or220oriented or configured to face a second angular surface141bor241bof the at least two angular surfaces141aand141bor241. The inspection tool100or200may further include the support platform (e.g., which may be included in or may be the external surface170).

According to an aspect of the present disclosure, the method400may include (e.g., further include) placing the specimen150,250or350on the support platform (e.g., which may be included in or may be the external surface170).

According to an aspect of the present disclosure, the method400may include (e.g., further include) a step403capturing an image (e.g., a first image) of the first angular surface141aor241ausing the first image capture unit110or210and capturing an image (e.g., a second image) of the second angular surface141bor241busing the second image capture unit120or220(e.g., after placing the specimen150,250or350on the support platform), for inspection of the specimen150,250or350.

According to an aspect of the present disclosure, in the method400, the optical axis of the first image capture unit110or210may be substantially perpendicular to the first angular surface141aor241a. Further, the optical axis of the second image capture unit120or220may be substantially perpendicular to the second angular surface141bor241b.

According to an aspect of the present disclosure, in the method400, the first channel140,240or340may further include the floor surface143or243143or243that may be substantially parallel with the base surface151or251of the specimen150,250or350. The floor surface143or243143or243may be adjoined to and may be positioned between the first angular surface141aor241aand the second angular surface141bor241b.

According to an aspect of the present disclosure, in the method400, the inspection tool100or200may further include the third image capture unit130or230which may be oriented or configured to face the floor surface143or243143or243. According to an aspect of the present disclosure, the method400may include (e.g., further include) capturing an image (e.g., a third image) of the floor surface143or243143or243using the third image capture unit130or230.

According to an aspect of the present disclosure, the method400may include (e.g., further include) stitching the captured first image, second image, and third image to form a composite image of the first channel140,240or340. For example, the first image may be cropped in a manner such that only an image of the first angular surface141aor241aremains (or is shown) (herein referred to as “first cropped image”). Further, the second image may be cropped in a manner such that only an image of the second angular surface141bor241bremains (herein referred to as “second cropped image”). Yet further, the third image may be cropped in a manner such that only an image of the floor surface143or243143or243remains (herein referred to as “third cropped image”). The method400may include stitching the first cropped image, the second cropped image, and the third cropped image (e.g., with the third cropped image between the first and the second cropped images) form the composite image of the first channel140,240or340.

According to another aspect of the present disclosure, the method400may include (e.g., further include) stitching the captured first image and second image to form a composite image of the first angular surface141aor241aand second angular surface141bor241bof the first channel140,240or340.

According to an aspect of the present disclosure, the method400may include (e.g., further include) analysing the captured first image, second image and third image (e.g., using the processor88) for identifying defects and/or contamination. In particular, the method400may include (e.g., further include) analysing the composite image of the first channel140,240or340or the composite image of the first angular surface141aor241aand second angular surface141bor241bof the first channel140,240or340.

According to an aspect of the present disclosure, the method400may include (e.g., further include) operating at least the first image capture unit110or210and the second image capture unit120or220simultaneously. In particular, the first image capture unit110or210and the second image capture unit120or220of the inspection tool100or200may be configured to operate simultaneously to capture the first image of the first angular surface141aor241aand the second image of the second angular surface141bor241bat a same time.

According to an aspect of the present disclosure, the method400may include (e.g., further include) operating at least the first image capture unit110or210, the second image capture unit120or220, and the third image capture unit130or230simultaneously. In particular, the first image capture unit110or210, the second image capture unit120or220, and the third image capture unit130or230of the inspection tool100or200may be configured to operate simultaneously to capture the first image of the first angular surface141aor241a, the second image of the second angular surface141bor241b, and the third image of the floor surface143or243143or243at a same time.

According to an aspect of the present disclosure, any one or more of the first image capture unit110or210and/or the second image capture unit120or220and/or the third image capture unit130or230may be configured to be operated (e.g., simultaneously) at regular, or irregular, time intervals in order to or for capturing a sequence or particular sequence of events (e.g., temporal-related events, for example, movement of a particle or contaminant across a width of a V-groove).

Accordingly, operating a plurality or all image capture units directed to a channel (e.g., first channel140,240or340or secondary channel345) of the specimen150,250or350simultaneously, at time intervals (e.g., regular time intervals), a temporal (e.g., time-related) account (e.g., depiction or understanding) of movement, e.g., of a particle, contamination particle, or a fluid, across the said channel (e.g., first channel140,240or340or secondary channel345) of the specimen150,250or350may be established.

According to an aspect of the present disclosure, the method400may include (e.g., further include) moving the specimen150,250or350, in the first direction (e.g., in a same direction in which the channel is extending along), with respect to at least the first image capture unit110or210and the second image capture unit120or220(and, optionally, the third image capture unit130or230) of the inspection tool100or200.

According to an aspect of the present disclosure, within the method400, the specimen150,250or350may further include the (e.g., at least one) secondary channel345for receiving the object (e.g., optical fiber). Accordingly, the secondary channel345may be positioned in and/or may be extending along the top surface152or252(e.g., top surface152or252) of the specimen150,250or350in the first direction, and the secondary channel345may be adjacent to the first channel140,240or340. Further, the secondary channel345may be defined by at least two secondary angular surfaces346of the specimen150,250or350, the at least two secondary angular surfaces346being non-parallel with the base surface151or251of the specimen150,250or350and may be oriented with respect to the base surface151or251differently from one another.

According to an aspect of the present disclosure, the method400may include (e.g., further include) moving the specimen150,250or350, in a second direction substantially perpendicular to the first direction, such that the first image capture unit110or210of the inspection tool100or200may face or be directed towards the first secondary angular surface346aof the secondary channel345and the second image capture unit120or220of the inspection tool100or200may face or be directed towards the second secondary angular surface346bof the secondary channel345. The method400may further include capturing an image of the first secondary angular surface346ausing the first image capture unit110or210and capturing an image of the second secondary angular surface346busing the second image capture unit120or220, for example (e.g., after moving the specimen150,250or350in the second direction as described). The method400may further include capturing an image of the secondary floor surface348using the third image capture unit130or230.

According to an aspect of the present disclosure, within the method400, the specimen150,250or350may be a semiconductor substrate (e.g., silicon substrate).

According to an aspect of the present disclosure, the method400may include (e.g., further include) placing the object in the first channel140,240or340after capturing the first image and the second image. According to an aspect of the present disclosure, when the inspection tool100or200includes the third image capture unit130or230, the method400may include (e.g., further include) placing the object in the first channel140,240or340after capturing the first image, the second image, and the third image.

According to an aspect of the present disclosure, within the method400, each of the first channel140,240or340and/or the secondary channel345may be formed using an etching process on the semiconductor substrate.

According to an aspect of the present disclosure, within the method400, each of the first angular surface141aor241aand the second angular surface141bor241bof the first channel140,240or340may form an opposing angle with the base surface151or251of the specimen150,250or350of between substantially 50 degrees to substantially 60 degrees. Further, each of the first secondary angular surface346aand the second secondary angular surface346bof the secondary channel345may form an opposing angle with the base surface151or251of the specimen150,250or350of between substantially 50 degrees to substantially 60 degrees.

According to an aspect of the present disclosure, within the method400, the first angular surface141aor241aand the second angular surface141bor241bof the first channel140,240or340may form an angle with respect to each other of between substantially 60 degrees to substantially 80 degree. Further, the first secondary angular surface346aand the second secondary angular surface346bof the secondary channel345may form an angle with respect to each other of between substantially 60 degrees to substantially 80 degree.

According to an aspect of the present disclosure, the method400may include (e.g., further include) configuring each image capture unit (e.g., first image capture unit110or210, second image capture unit120or220, third image capture unit130or230etc.) of the inspection tool100or200to have a numerical aperture of less than 0.95.

According to an aspect of the present disclosure, the method400may include (e.g., further include) configuring any one or all image capture unit(s) (e.g., first image capture unit110or210, second image capture unit120or220, third image capture unit130or230etc.) of the inspection tool100or200with a pixel resolution of substantially 500 nm.

According to an aspect of the present disclosure, the method400may include (e.g., further include) configuring any one or all image capture unit(s) (e.g., first image capture unit110or210, second image capture unit120or220, third image capture unit130or230etc.) of the inspection tool100or200with a field of view of substantially 3.5 mm by 5 mm.

According to an aspect of the present disclosure, the method400may include (e.g., further include) configuring any one or all image capture unit(s) (e.g., first image capture unit110or210, second image capture unit120or220, third image capture unit130or230etc.) of the inspection tool100or200with a depth of field of substantially 30 μm.

FIG.5Ashows a schematic front view of an optical fiber core18a, on a V-groove540of a specimen550, that is misaligned with a waveguide19on a silicon PIC.

The specimen550ofFIG.5Amay be similar or identical to the specimen150ofFIG.1or the specimen250ofFIG.2Aor the specimen350ofFIG.3.

According to an aspect of the present disclosure, the specimen550may be a single crystal silicon wafer. At least one V-groove540of the specimen550may be anisotropically etched out in the single crystal silicon wafer, for example, using one or more photolithographically defined masks (not shown). For example, a width and position of the photolithographically mask(s) (e.g., on the single crystal silicon wafer) as well as an etch rate (e.g., control of an etch rate) may determine a shape and/or position of each formed V-groove540. Both wet etching and dry etching may be used in such V-groove540formation.

As shown, the optical fiber18(i.e. an object) may be guided and supported by opposing sidewalls541(e.g., angular surfaces) of the V-groove540. During a fiber attachment process, a buffer lid (not shown) may be used to press downwards or against the optical fiber18(e.g., in a direction towards a bottom543of the V-groove540) from the top surface552of the specimen550to ensure contact (e.g., direct or physical contact) between the optical fiber18and the sidewalls541of the V-groove540. A slope of the sidewalls541(e.g., angular surfaces) of the V-groove540which may be, for example, about 55 degrees from a horizontal (e.g., 54.74 degrees), may be defined by silicon crystal structure orientation since etching rates in different crystal orientations may be different. Non-ideal shape, location and orientation of the V-groove540may lead to misalignment between the optical fiber18and the waveguide19(as shown inFIG.5A, e.g., optical fiber core18ais not aligned with waveguide19) in or on the PIC (e.g., silicon PIC), which may result in lower optical coupling efficiency. Any contamination larger than 1 μm on the sidewalls541of the V-groove540may be another cause for misalignment between the optical fiber18and the waveguide19since any such contamination (e.g., particle, contaminant etc.) may misposition or misplace or misalign the optical fiber18(e.g., with respect to the waveguide19) (as shown inFIG.5A). Therefore, it may be crucial or important to ensure cleanliness of the V-groove540and the optical fiber18.

FIG.5Bis a graph depicting an optical coupling efficiency's dependence on lateral translation misalignment and angular mismatch.

FIG.5Bmay be used to understand a misalignment tolerance between the optical fiber18and the waveguide19in or on the PIC, with respect to lateral translation and angular degrees of freedom. With reference toFIG.5B, a 2 μm of lateral translation misalignment and/or 2 degrees of angular misalignment may lead to about 20% light loss. In aspects involving a photonic integrated device, no more than 20% light loss may be afforded for one single optical interface. Therefore, good alignment both in translation and angular degrees of freedom may be essential.

FIG.6AandFIG.6Bare photographs of prototype inspection tools601and602, according to various aspects of the present disclosure.

In an aspect, the inspection tools601and602ofFIG.6AandFIG.6Bmay be prototypes (e.g., full or partial prototypes) of the inspection tool100ofFIG.1or the inspection tool200ofFIG.2AandFIG.3. In an aspect, the prototype inspection tools601and602may be configured to inspect the specimen550ofFIG.5A.

The prototype inspection tools601and602may be referred to as an “all-surface V-groove 2D inspection system” and may be capable of detecting any defects and/or any contaminants or particles (e.g., submicron-sized contaminations or particles) on the V-groove540of the specimen550.

As shown, the prototype inspection tool601may include two sidewall orientated vision systems610and620(i.e. first image capture unit610and second image capture unit620), which may be similar or identical to the first image capture unit110or210and the second image capture unit120or220of the inspection tool100ofFIG.1or the inspection tool200ofFIG.2AandFIG.3. Accordingly, the two sidewall orientated vision systems610and620may be oriented to be directed to the opposing sidewalls541(e.g., angular surfaces) of the V-groove540of the specimen550(e.g., when the specimen550is placed on a platform670). As an example, in an aspect, each of the two sidewall orientated vision systems610and620may be or may include a 2-dimensional camera.

In an aspect, the prototype inspection tool602may include one top-down vision system630(i.e. a third image capture unit630), which may be similar or identical to the third image capture unit130or230of the inspection tool100ofFIG.1or the inspection tool200ofFIG.2AandFIG.3. Accordingly, the top-down vision system630may be oriented to be directed to a plateau543(e.g., horizontal inner surface or floor surface) of the V-groove540of the specimen550between the opposing sidewalls541(e.g., angular surfaces) of the V-groove540and/or directed to a top surface552of the specimen550. As an example, in an aspect, the top-down vision system630may be or may include a 2-dimensional camera.

FIG.7Ashow an image captured using the first image capture unit610and the second image capture unit620of the prototype inspection tool601, according to various aspects of the present disclosure.

With reference toFIG.7A, the sidewall orientated vision systems610and620(i.e. image capture units) may be focused on (e.g., only on) the opposing sidewalls541(e.g., angular surfaces) of the V-groove540(e.g., one vision system/image capture unit to one sidewall) such that the sidewall orientated vision systems610and620may be capable of capturing a focused or sharp image of the opposing sidewalls541but not of the plateau543(e.g., horizontal inner surface) and/or the top surface552of the specimen550.

FIG.7Bshow an image captured using the third image capture unit630of the prototype inspection tool602, according to various aspects of the present disclosure.

With reference toFIG.7B, the top-down vision system630may be focused on (e.g., only on) the plateau543(e.g., horizontal inner surface) and/or the top surface552of the specimen550such that the top-down vision system630may be capable of capturing a focused or sharp image of the plateau543(e.g., horizontal inner surface) and/or the top surface552of the specimen550but not of the opposing sidewalls541.

FIG.7Cshow a composite image701formed by stitching the images captured using the first image capture unit610, the second image capture unit620, and the third image capture unit630of the prototype inspection tools601and602, according to various aspects of the present disclosure.

The images captured by the three imaging systems (i.e. the sidewall orientated vision systems610and620and the top-down vision system630) of the prototype inspection tools601and602may (e.g., optionally) be stitched together to form a composite image701for better visualization of the V-groove(s) (e.g., of a first channel or a secondary channel) of the specimen550(e.g., for contamination detection purposes).

Specifically, referring back toFIG.7B, the image shown is taken by the top-down vision system630configured with a numerical aperture of 0.95 so as to be capable of capturing a focused or sharp image of the plateau543(e.g., horizontal inner surface) and/or the top surface552of the specimen550but not of the opposing sidewalls541of a channel. In the image shown inFIG.7B, the opposing sidewalls541appear darker (e.g., in color and/or contrast) as compared to the plateau543(e.g., horizontal inner surface) and/or the top surface552of the specimen550due to the opposing sidewalls541being inclined (e.g., being a steep slope) with respect to an optical axis of the top-down vision system630, thereby leading to much lower light collection efficiency by the top-down vision system630of these inclined opposing sidewalls541.

On the other hand,FIG.7Ashows an image taken by the sidewall orientated vision systems610and620configured with a much lower numerical aperture than the top-down vision system630, such that the sidewall orientated vision systems610and620may be capable of capturing a focused or sharp image of the opposing sidewalls541of a channel, but not of the plateau543(e.g., horizontal inner surface) and/or the top surface552of the specimen550, since only each sidewall541may be perpendicular (e.g., substantially perpendicular) to an optical axis of a corresponding (e.g., one) vision system (e.g., image capture unit) of the sidewall orientated vision systems610and620but may be inclined or non-perpendicular with respect to the optical axis of the top-down vision system630. In an aspect, a depth of field of each vision system (e.g., image capture unit) of the sidewall orientated vision systems610and620may be configured in a manner such that a pair (e.g., only a pair) of opposing sidewalls541(e.g., of a first channel) may appear in focus while other sidewalls546(e.g., of one or more secondary channels which may be spaced apart from the first channel by about 200 μm) may be out of focus.

The in-focus sidewall images, e.g., captured by the sidewall orientated vision systems610and620, of each channel may be cropped and stitched together as shown inFIG.7C. InFIG.7C, a foreign material50(e.g., contaminant) of about 15 μm in diameter is circled. In addition, from the sidewall images shown inFIG.7C, it may be readily observed that etched surface(s)541and/or546of the V-groove540of the specimen550may not be completely smooth, which may be validated to be around 500 nm by utilizing 3D profilers (not shown).

FIG.8is a photograph of another prototype inspection tool801, according to various aspects of the present disclosure.

In an aspect, the inspection tool801ofFIG.8may be another prototype (e.g., full or partial prototype) of the inspection tool100ofFIG.1or the inspection tool200ofFIG.2AandFIG.3. In an aspect, the prototype inspection tool801may be configured to inspect the specimen550ofFIG.5A.

As shown, the prototype inspection tool801may include two triangulation sensors (e.g., two 3-dimensional profilers) (i.e. first image capture unit810and second image capture unit820), which may be similar or identical to the first image capture unit110or210and the second image capture unit120or220of the inspection tool100ofFIG.1or the inspection tool200ofFIG.2AandFIG.3. Accordingly, the two triangulation sensors810and820(i.e. two image capture units) may be oriented to be directed to the opposing sidewalls541(e.g., two substantially opposing angular surfaces) of the V-groove540of the specimen550(e.g., when the specimen550is placed on a platform870).

With the prototype inspection tools601and602ofFIG.6AandFIG.6B, which may (as an example) use or include 2-dimensional cameras (i.e. 2-dimensional image capture units) for 2-dimensional inspection of a specimen, spatial relation between the various or multiple 2-dimensional cameras (i.e. 2-dimensional image capture units) may not be required or determined (e.g., for an inspection of a specimen). On the other hand, with the prototype inspection tool801ofFIG.8, which may (as an example) use or include 3-dimensional profilers (i.e. 3-dimensional image capture units), spatial relations of or between the 3-dimensional profilers (i.e. image capture units) may be required to be determined or well-defined (e.g., for an inspection of a specimen). Hence, according to various aspects of the present disclosure, use of 3-dimensional profilers (i.e. 3-dimensional image capture units) may involve calibration (e.g., before an inspection of a specimen) to register relative position(s) and/or direction(s) and/or orientation(s) (e.g., with sub-micrometer precision or tolerances) of such 3-dimensional profilers of an inspection tool according to various aspects of the present disclosure. Accordingly, based on the calibrated relative position and/or direction and/or orientation of each 3-dimensional profiler of an inspection tool, according to various aspects of the present disclosure, with respect to each other (e.g., each or all remaining) 3-dimensional profiler(s) of the inspection tool (e.g., prototype inspection tool801), a 3-dimensional profile (e.g. line profile) of a surface (e.g., of a V-groove) of a specimen may be produced or obtained via the 3-dimensional profilers of the inspection tool (e.g., by stitching or synthesizing the captured images by the 3-dimensional profilers of the inspection tool together based on data of the relative position and/or direction and/or orientation of each 3-dimensional profiler with respect to each other 3-dimensional profiler of the inspection tool used for inspection of the specimen).

FIG.9is a graph900, depicting a line profile of V-grooves of a specimen (not shown), obtained using at least two laser confocal 3-dimensional profiler (i.e. image capture units) of an inspection tool (not shown).

FIG.10is a table1000depicting a magnitude of any optical fiber core misalignment with respect to a waveguide in a PIC (not shown) based on an inspection method using 3-dimensional profilers (i.e. image capture units) of an inspection tool (not shown).

For example, with reference toFIG.10, if an optical fiber (e.g., for a semiconductor application) is placed on or in a first V-groove1001of a specimen (not shown), it may be observed from the table1000that the optical fiber may be vertically misaligned from the waveguide in PIC by 1.39 μm, horizontally misaligned from the waveguide in PIC by 0.25 μm, and radially misaligned from the waveguide in PIC by 1.41 μm.

To more readily understand and put into practical effect the present metrology system and methods for their use in gap measurements, they will now be described by way of examples. For the sake of brevity, duplicate descriptions of features and properties may be omitted.

EXAMPLES

Example 1 provides an inspection method which may include providing a specimen for inspection, the specimen may include a base surface, a top surface opposite the base surface, a first channel positioned in the top surface in a first direction for receiving an object therein. The first channel may be formed by at least two angular surfaces of the specimen, the at least two angular surfaces declining from the top surface of the specimen. The inspection method may further include providing an inspection tool to inspect the specimen, the inspection tool may include (i) a first image capture unit oriented to face a first angular surface of the at least two angular surfaces and (ii) a second image capture unit oriented to face a second angular surface of the at least two angular surfaces. The inspection method may further include capturing a first image of the first angular surface using the first image capture unit and capturing a second image of the second angular surface using the second image capture unit, for inspection of the specimen.

Example 2 may include the method of example 1 and/or any other example disclosed herein, for which an optical axis of the first image capture unit may be substantially perpendicular to the first angular surface and an optical axis of the second image capture unit may be substantially perpendicular to the second angular surface.

Example 3 may include the method of example 1 and/or any other example disclosed herein, for which the first channel further may include a floor surface that is substantially parallel with the base surface of the specimen, for which the floor surface may be adjoined to and may be positioned between the first angular surface and the second angular surface. Further, in Example 3, the inspection tool may further include a third image capture unit oriented to face the floor surface, and the method may include capturing a third image of the floor surface using the third image capture unit.

Example 4 may include the method of example 3 and/or any other example disclosed herein, for which the method may further include stitching the captured first image, second image and third image together to form a composite image of the first channel, and analysing the captured first image, second image and third image using a processor for identifying defects or contamination along the first channel.

Example 5 may include the method of example 1 and/or any other example disclosed herein, for which the first image capture unit and the second image capture unit of the inspection tool may be configured to operate simultaneously to capture the first image of the first angular surface and the second image of the second angular surface at a same time.

Example 6 may include the method of example 1 and/or any other example disclosed herein, for which the method may further include moving the specimen, in the first direction, with respect to the first image capture unit and the second image capture unit of the inspection tool.

Example 7 may include the method of example 1 and/or any other example disclosed herein, for which the specimen may further include a secondary channel, positioned in the top surface of the specimen and in the first direction, for receiving the object therein. Further, in Example 7, the secondary channel may be formed by at least two secondary angular surfaces of the specimen, the at least two secondary angular surfaces declining from the top surface of the specimen. Further, in Example 7, the secondary channel may be adjacent to the first channel.

Example 8 may include the method of example 7 and/or any other example disclosed herein, for which the method may further include moving the specimen, in a second direction substantially perpendicular to the first direction, such that the first image capture unit of the inspection tool faces a first secondary angular surface of the secondary channel and the second image capture unit of the inspection tool faces a second secondary angular surface of the secondary channel, and thereafter, capturing an image of the first secondary angular surface using the first image capture unit and capturing an image of the second secondary angular surface using the second image capture unit.

Example 9 may include the method of example 1 and/or any other example disclosed herein, for which the specimen is a semiconductor substrate and the object is an optical fiber.

Example 10 may include the method of example 1 and/or any other example disclosed herein, for which the method may further include placing the object in the first channel after capturing the first image and the second image.

Example 11 may include the method of example 1 and/or any other example disclosed herein, for which the first angular surface and the second angular surface of the first channel may respectively form an opposing angle with the base surface of the specimen of between substantially 50 degrees to substantially 60 degrees.

Example 12 may include the method of example 1 and/or any other example disclosed herein, for which the first angular surface and the second angular surface of the first channel may form an angle with respect to each other of between substantially 60 degrees to substantially 80 degree.

Example 13 may include the method of example 1 and/or any other example disclosed herein, for which the method may further include configuring each image capture unit of the inspection tool to have a numerical aperture of less than 0.95.

Example 14 may include the method of example 1 and/or any other example disclosed herein, for which the method may further include configuring each image capture unit of the inspection tool with a pixel resolution of substantially 500 nm, a field of view of substantially 3.5 mm by 5 mm, and a depth of field of substantially 30 μm.

Example 15 may include the method of example 1 and/or any other example disclosed herein, for which an opening on the top surface of the specimen for providing access to the first channel has a lateral width of not more than 200 μm.

Example 16 provides an inspection method which may include providing a specimen for inspection, the specimen including a base surface, a top surface opposite the base surface, a substantially V-shaped groove formed in the top surface of the specimen, for receiving an optical fiber therein, the groove being defined by a floor surface that is substantially parallel with the base surface of the specimen and two angular surfaces extending from the floor surface towards an opening of the groove at the top surface, for which the two angular surfaces are declining from the top surface of the specimen, and each of the two angular surfaces forms an angle of between 50 degrees to 60 degrees with respect to the base surface. Further, Example 16 may include providing an inspection tool comprising (i) a first image capture unit configured to face a first of the two angular surfaces and (ii) a second image capture unit configured to face a second of the two angular surfaces, and capturing an image of the first angular surface using the first image capture unit and capturing an image of the second angular surface using the second image capture unit.

Example 17 may include the method of example 16 and/or any other example disclosed herein, for which an optical axis of the first image capture unit of the inspection tool may be substantially perpendicular to the first of the two angular surfaces and an optical axis of the second image capture unit of the inspection tool may be substantially perpendicular to the second of the two angular surfaces.

Example 18 may include the method of example 16 and/or any other example disclosed herein, for which the first image capture unit and the second image capture unit may be configured identically, with a respective numerical aperture of less than 0.95, a respective pixel resolution of substantially 500 nm, a respective field of view of substantially 3.5 mm by 5 mm, and a respective depth of field of substantially 30 μm.

Example 19 may provide an optical inspection tool which may include at least a first image capture unit and a second image capture unit for inspecting specimens having one or more substantially V-shaped grooves, for which the first image capture unit arranged in a first orientation may be directable towards a first angular surface of a first V-shaped groove of a first specimen, and for which the second image capture unit arranged in a second orientation may be directable towards a second angular surface of the first V-shaped groove of the first specimen. Further, the first image capture unit may be configured to capture images of defects or contamination on the first angular surface and the second image capture unit may be configured to capture images of defects or contamination on the second angular surface.

Example 20 may include the optical inspection tool of example 19 and/or any other example disclosed herein, for which the optical inspection tool may further include a third image capture unit arranged in a third orientation being directable towards a bottom surface of the groove positioned between and adjoining the first angular surface and the second angular surface of the V-shaped groove, for which the third image capture unit may be configured to capture images of defects or contamination on the bottom surface. The optical inspection tool may further include a processor coupled to the first image capture unit, the second image capture unit, and the third image capture unit to analyse the captured images by the first image capture unit, the second image capture unit, and the third image capture unit.