Laser-assisted electron-beam inspection for semiconductor devices

Methods and apparatuses for laser-assisted electron-beam inspection (EBI) are provided. The apparatus includes an EBI device and a laser illumination device. The EBI device includes an e-beam source configured to emit an incident e-beam, a deflector configured to deflect the incident e-beam to be projected onto a surface of a semiconductor device, and an electron detector configured to detect emergent electrons generated by the incident e-beam projected onto the surface. The laser illumination device includes a laser source configured to generate a laser, and a guiding device configured to guide the laser to be projected onto the semiconductor device. The laser changes the emergent electrons to cause, in a positive mode of the EBI apparatus, a PN junction of an NMOS of the semiconductor device to be in a conduction state.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to Chinese Patent Application No. 201810392501.7, filed on Apr. 27, 2018, the content of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

This disclosure relates to the field of semiconductor inspection technologies, in particular, to laser-assisted electron-beam (e-beam) inspection of semiconductor devices, and specifically, to apparatuses and methods of e-beam defect inspection of complementary metal-oxide semiconductor (CMOS) integrated circuits (ICs).

BACKGROUND

In recent years, e-beam inspection (EBI) devices have been used for defect detection of chips in the semiconductor industry. For example, the defect detection can include detection of open circuits or short circuits in CMOS (e.g., disconnection between the CMOS and contact holes). A CMOS-type IC can include two basic types of units: an N-type metal-oxide semiconductor (NMOS) and a P-type metal-oxide semiconductor (PMOS).

The EBI device can work in different charging modes (e.g., a positive charging mode or a negative charging mode) for defect detection of the CMOS. However, for defect detection, different types of units of the CMOS can require different charging modes or different bias voltages of the EBI device, which can slow down the EBI process.

SUMMARY

Disclosed herein are implementations of methods, apparatuses, and systems for laser-assisted electron-beam inspection.

In an aspect, an apparatus for laser-assisted electron-beam inspection is disclosed. The apparatus includes an EBI device and a laser illumination device. The EBI device includes an e-beam source configured to emit an incident e-beam, a deflector configured to deflect the incident e-beam to be projected onto a surface of a semiconductor device, and an electron detector configured to detect emergent electrons generated by the incident e-beam projected onto the surface. The laser illumination device includes a laser source configured to generate a laser, and a guiding device configured to guide the laser to be projected onto the semiconductor device. The laser changes the emergent electrons by a photovoltaic effect to cause, in a positive mode of the EBI apparatus, a PN junction of an N-type metal-oxide semiconductor (NMOS) of the semiconductor device to be in a conduction state.

In another aspect, a method for laser-assisted electron-beam inspection is disclosed. The method includes detecting, using an apparatus in a simultaneous manner, whether an open-circuit defect exist in a metal contact hole corresponding to a P-type metal-oxide semiconductor (PMOS) of a semiconductor device or a metal contact hole corresponding to an N-type metal-oxide semiconductor (NMOS) of the semiconductor device. The apparatus comprises an electron detector, and the apparatus further comprises an EBI device that is in a positive mode and a laser illumination device. The EBI device includes an e-beam source configured to emit an incident e-beam, a deflector configured to deflect the incident e-beam to be projected onto a surface of a semiconductor device, and an electron detector configured to detect emergent electrons generated by the incident e-beam projected onto the surface. The laser illumination device includes a laser source configured to generate a laser, and a guiding device configured to guide the laser to be projected onto the semiconductor device. The laser changes the emergent electrons to cause a PN junction of the NMOS to be in a conduction state.

DETAILED DESCRIPTION

The technical solutions of this disclosure will be described in detail by way of examples with reference to the accompanying drawings. In this disclosure, the same or similar reference numerals and letters indicate the same or similar parts. The following description of the implementations of this disclosure is intended to be illustrative and not to be construed as any limitation to this disclosure.

The drawings are used to illustrate the disclosure. The dimensions and shapes of the various components in the drawings do not reflect the true proportions of the components of the laser-assisted e-beam inspection device for semiconductor devices.

The working principles of this disclosure are set forth as below.

For CMOS-type ICs, disconnection between the CMOS and a contact hole is one of the most common defects. Detection of the disconnection between the CMOS and the contact hole can be implemented as follows. An EBI device can be in a positive charging mode (or “positive mode” for simplicity). In the positive mode, an incident e-beam can be projected to a surface (referred to as a “test surface”) of a sample (referred to as a “test sample”) of a semiconductor device to be inspected, and a ratio (or a “yield”) of secondary electrons (i.e., electrons generated as ionization by the incident e-beam) to primary electrons (i.e., electrons of the incident e-beam) is greater than 1. A PN junction of the PMOS can be forward biased (or “in a forward bias state”) in the positive mode. Positive charges do not accumulate at a point of a metal contact hole corresponding to the PN junction, so the yield of the secondary electrons can maintain unchanged if there is no defect in the PMOS. When there is an open-circuit defect (e.g., in the PN junction or an electrical path of the PMOS), the positive charges can accumulate to a level that can attract the secondary electrons at the point of the metal contact hole, and further lower the yield of the secondary electrons. As a result, in an inspection image generated by the EBI device, the image region corresponding to the open-circuit defect can be darker than image regions corresponding to portions of the PMOS that have no defect, by which the open-circuit defect can be identified for the PMOS. However, in the positive mode, a PN junction of the NMOS can be reverse biased (or “in a reverse bias state”). In the reverse bias state, no matter whether the NMOS is in contact with a corresponding metal contact hole, the accumulated charges thereon cannot be drained. As a result, based on the inspection image of the metal contact hole corresponding to the NMOS generated by the EBI device, it can be difficult to differentiate an electrically connected metal contact hole and an open-circuit defect thereof, which is easy to cause a misjudgment in defect detection. Therefore, by using the positive mode only, it can be ineffective to differentiate whether an open-circuit defect exist in a metal contact hole corresponding to the NMOS.

On the other hand, when the EBI device is in a negative charging mode (or “negative mode” for simplicity), according to the principles described as above, only the open-circuit defects in the NMOS can be detected. In the negative mode, the yield of the secondary electrons is smaller than 1. The negative mode can be implemented by increasing the energy of a scanning e-beam. The open-circuit defects in the NMOS can be represented in the inspection image as an image region brighter than image regions corresponding to portions of the NMOS that have no defect. However, in the negative mode, it can be ineffective to differentiate whether an open-circuit defect exist in a metal contact hole corresponding to the PMOS.

In addition, if the EBI device applies a strong electric field, the PN junction of the NMOS can be reversely broken down, by which the charge accumulated on the NMOS can be drained. In this situation, it is possible to detect whether an open-circuit defect exist in a metal contact hole corresponding to the NMOS. However, the introduction of the strong electric field can also bring design difficulties and risks of permanent damage to the semiconductor device to be inspected (e.g., the PMOS and/or the NMOS).

In some implementations of this disclosure, an EBI apparatus is in a normal working state (i.e., in which the EBI apparatus is in the positive mode). An additional laser beam is illuminated onto a test sample of the semiconductor device under inspection to induce a photovoltaic effect that can change emergent electrons (e.g., secondary electrons and/or backscattered electrons). Specifically, the photovoltaic effect can modulate the I-V curve of the NMOS, causing an electric potential (that is generated by a charging effect of the illuminated sample) of a surface of the NMOS to drop, and eventually changing the emergent electrons. Thus, via the photovoltaic effect, the laser projected on PN junctions of a CMOS of the semiconductor device can change the emergent electrons, such that, under a normal working state of the EBI apparatus (i.e., the EBI apparatus is in the positive mode), a PN junction of a PMOS of the CMOS of the semiconductor device is in a forward bias status, and a PN junction of an NMOS of the CMOS is in a conduction state due to being short-circuited by the photovoltaic effect. Due to the photovoltaic effect, electric charges accumulated on the NMOS can be drained via a corresponding metal contact hole well connected to the NMOS. Therefore, in a single detection process under the normal working state (in which the EBI is in the positive mode) of the electron detector, it can be simultaneously detected whether an open-circuit defect exists in respective metal contact holes corresponding to the PMOS and the NMOS. In some other implementations, utilization rate of the laser energy can be improved by reducing optical energy loss caused by reflection of the laser beam by the test sample. In some implementations, some practical conditions are further considered, such as spatial limitation caused by limited internal apparatus structures due to positioning a laser source inside the EBI apparatus, an oblique incident angle of the laser beam due to the spatial limitation, variation of a shape of a laser spot projected onto an effective illumination region of the test surface due to the oblique incident angle of the laser beam, or non-uniform distribution of the laser spot due to intrinsic property of a Gaussian distribution of the laser beam. Accordingly, beam shaping is introduced for the laser beam projected onto the effective illumination region of the test surface.

FIG. 1is a diagram of an example EBI apparatus according to implementations of this disclosure.FIG. 2is a structure diagram of the EBI apparatus as shown inFIG. 1.

As shown inFIGS. 1 and 2, a laser-assisted EBI apparatus1for defect inspection of a test sample of a semiconductor device includes an EBI device10serving as a main component and a laser illumination device20serving as an auxiliary component. The semiconductor device can include a silicon wafer. The laser illumination device20can use a laser to illuminate a surface of the test sample (i.e., a test surface) to cause the photovoltaic effect. Specifically, the EBI device10includes an e-beam source110configured to emit an incident e-beam (or “e-beam” for simplicity), a deflector120configured to deflect the incident e-beam to project the same onto the test surface of the semiconductor device, and an electron detector130configured to detect emergent electrons (e.g., backscattered electrons and secondary electrons) generated by the projection of the incident e-beam onto the test surface. Moreover, the laser illumination device20includes a laser source210configured to generate a laser, and a guiding device220configured to guide the laser to be projected onto the semiconductor device. The laser projected onto PN junctions of the semiconductor device can change the emergent electrons by the electric potential caused by the photovoltaic effect. Under a normal working state of the electron detector, a PN junction of a PMOS in a CMOS of the semiconductor device is in a forward bias state, and a PN junction of an NMOS of the CMOS is in a conduction state due to being short-circuited by the photovoltaic effect. Therefore, under the normal working state of the electron detector, it can be simultaneously detected whether an open-circuit defect exists in respective metal contact holes corresponding to the PMOS and the NMOS.

As shown inFIG. 1, arrows inFIG. 1indicate laser beams obliquely incident from the outside of the EBI apparatus toward the test surface. As shown inFIG. 1, the laser illumination device20can be entirely included in an integral structure of the EBI apparatus, such as, inside a cavity of a system that produces the e-beam. In other words, an internal light-path design is employed, thereby enabling the laser beam to be incident on the test surface inside the EBI apparatus at a smaller angle. According to the Fresnel formula, when the incident angle of the beam is small, the reflectivity is low, and the semiconductor device (e.g., a silicon wafer) can absorb more optical energy, by which the photovoltaic effect can be caused more easily, and the utilization of optical energy can be improved.

As shown inFIG. 2, the guiding device220includes a beam shaper2201(or2201′, seeFIG. 4) and a first reflector2202. The beam shaper2201(2201′) can be configured to shape the laser to form a laser spot that is uniform and in a predetermined shape. The first reflector2202can be located downstream the beam shaper2201(2201′) and configured to receive the shaped laser and reflect it to the test surface in a predetermined range of angles.

In some implementations, as shown inFIG. 2, the guiding device220can include the beam shaper2201(2201′) configured to shape the laser to form the laser spot that is uniform and in the predetermined shape. In some implementations, the first reflector2202can have an angle relative to the test surface and an optical axis of the beam shaper2201(2201′). The first reflector2202can be configured to receive the shaped laser and reflect it to the test surface in a predetermined range of angles. For example, based on a geometrical optical relationship, when the optical axis of the laser emitted by the laser source is horizontal, the first reflector2202can be a planar mirror obliquely arranged with respect to the horizontal direction or a concave mirror. If the first reflector2202is the planar mirror that has a tilt angle θ with respect to the horizontal direction, based on the geometrical optical relationship, an incident angle of the laser formed on the first reflector2202in the form of the planar mirror is β=90°−θ, and an incident angle of the laser incoming toward the horizontal test surface after reflection by the first reflector2202is α=90°−2θ. Thus, the larger the tilt angle θ with respect to the horizontal direction is, the smaller the incident angle α (at the test sample) of the laser is, and the lower reflectivity of the laser is at the incident location—that is, the more optical energy is absorbed by the semiconductor device (e.g., the silicon wafer). In this way, the photovoltaic effect can be caused more easily, and the utilization of the optical energy can be improved.

By shaping the laser beam incident on the test sample, uniformity of illumination of the laser spot formed by the laser beam on the test sample can be enhanced, and deformation of the laser spot caused by the oblique incidence of the laser beam toward the test sample can be improved. Furthermore, the optical energy in a unit illumination area can be increased, thereby increasing the utilization of optical energy.

In some implementations, as shown inFIG. 2, the guiding device220can further include an optical retroreflector2204and a second reflector2203. The optical retroreflector2204can be configured to receive an emergent laser from the test surface and reflect it back. The reflected laser can be referred to as a retroreflected laser. The second reflector2203can be disposed between the test surface and the optical retroreflector2204. The second reflector2203can be configured to reflect emergent laser from the test surface toward the optical retroreflector2204and reflect the retroreflected laser from the optical retroreflector2204toward the test surface.

For example, the second reflector2203can be used to receive the emergent beam reflected from the test surface and project the retroreflected laser onto the same effective position of the test surface at a different angle. For another example, the second reflector2203can be arranged such that the retroreflected laser projected onto the test surface is not reflected toward the laser source210, thereby minimizing interference between the incident laser and the retroreflected laser.

By additionally providing the optical retroreflector2204downstream the test sample in the laser illumination device20of the EBI apparatus1, a retroreflection path of the laser can be formed, thereby the energy of the reflected laser can be reused, and the utilization of the optical energy can be increased.

FIG. 3is a structure diagram of the beam shaper2201in the EBI apparatus1as shown inFIGS. 1 and 2.

In some implementations, as shown inFIG. 3, the beam shaper2201includes a first microlens array22010, and the first microlens array22010can include multiple microlenses arranged in the plane (e.g., the vertical plane shown inFIG. 3) orthogonal to an optical axis (e.g., the horizontal direction shown inFIG. 3) of the laser emitted by the laser source210. The first microlens array22010can be configured to uniformize the laser—that is, to divide the laser beam incident thereon into multiple uniformized sub-beams.

Further, for example, as shown inFIG. 3, the beam shaper2201can include a second microlens array22011. The second microlens array22011can also include multiple microlenses arranged in the plane (e.g., the vertical plane shown inFIG. 3) orthogonal to the optical axis (e.g., the horizontal direction shown inFIG. 3) of the laser emitted by the laser source210. The second microlens array22011can be disposed downstream the first microlens array22010and configured to function as a field lens for deflecting the light path to increase incidence of edge beams of the laser, increase incident flux, and further uniformize the laser.

Further, for example, as shown inFIG. 3, the beam shaper2201can include a first lens22012that can function as a focus lens. The first lens22012can be disposed between the second microlens array22011and the first reflector2202. The first lens22012can also be disposed between the first reflector2202and the test sample. The first lens22012can converge the sub-beams of the laser shaped by the first microlens array22010and the second microlens array22011as a combined beam toward the test surface.

For example, the first lens can be a Fourier lens and configured to change the laser spot from the beam shaper to be of a predetermined size on a rear focal plane of the Fourier lens.

Further, for example, as shown inFIG. 3, the beam shaper2201can include a collimating lens22013disposed between the laser source210and the first microlens array22011. The collimating lens22013can be configured to collimate the laser incident into the beam shaper2201from the laser source210. After being collimated by the collimating lens22013, the output beam spot can be, for example, in an elliptical shape. The output beam spot can be further modified by the first microlens array22010and the first reflector2202to change the light spot incident onto the test sample into a predetermined shape (e.g., a square or a circle).

In some implementations, the guiding device220can further include a scattering piece22020, which is shown using dotted lines to indicate that the scattering piece22020is an optional component. The scattering piece can be disposed between the second microlens array22011and the first lens22012. The scattering piece can be used to diverge and expand the sub-beams shaped by the first microlens array22010and the second microlens array22011to a sufficient extent before the sub-beams entering the first lens22012and being converged by the same, thereby facilitate subsequent mixing of the sub-beams.

According to the above implementations, by shaping and uniformizing the laser based on one or more microlens arrays, an energy distribution of the laser spot of the shaped laser projected toward the first reflector2202and converged on the test surface can be close to a flat top distribution, thereby making the laser beam uniform and the energy distribution thereof even. Therefore, the photovoltaic effect in the effective illumination region on the test sample caused by the laser can also be uniform, and it is convenient to simultaneously detect whether an open-circuit connection defect exists in respective metal contact holes corresponding to the PMOS and the NMOS in the entire effective illumination region.

FIG. 4is a structure diagram of the beam shaper2201′ in the EBI apparatus1as shown inFIGS. 1 and 2.

In some implementations, as shown inFIG. 4, for example, the beam shaper2201′ can include a pair of cylindrical lenses. The pair of cylindrical lenses can be coaxially disposed and configured to uniformize the laser. For example, the pair of cylindrical lenses can be orthogonal.

For example,FIG. 4shows a pair (e.g., two) of cylindrical lenses. An upstream cylindrical lens22014can be configured to collimate the laser beam in the y-axis direction. A downstream cylindrical lens22015can be configured to collimate the laser beam in the x-axis direction. Alternatively, the upstream cylindrical lens22014can be configured to collimate the laser beam in the x-axis direction, and the downstream cylindrical lens22015can be configured to collimate the laser beam in the y-axis direction. In other words, the upstream cylindrical lens22014and the downstream cylindrical lens22015are orthogonally arranged or oriented.

In some implementations, the beam shaper2201′ can further include a first lens22016disposed between the pair of cylindrical lenses (e.g., the upstream cylindrical lens22014and the downstream cylindrical lens22015) and the test surface. The first lens22016can converge the shaped laser toward the test surface. The first lens22016can also be disposed between the first reflector2202and the test sample.

In the above implementations, the laser source210, the upstream cylindrical lens22014, the downstream cylindrical lens22015, the first lens22016, and the first reflector2202can be configured to cooperate to make the spot incident on the test sample into any predetermined shape (e.g., a circle, a rectangular, or an oval).

In some implementations, the guiding device220can further include a scattering piece22030, which is not shown using dotted lines to indicate that the scattering piece22030is an optional component. The scattering piece can be disposed between the pair of cylindrical lenses (e.g., the upstream cylindrical lens22014and the downstream cylindrical lens22015) and the first lens22016. The scattering piece can be used to diverge and expand the sub-beams shaped by the pair of cylindrical lenses to a sufficient extent before the sub-beams entering the first lens22016, thereby facilitate subsequent mixing of the sub-beams.

According to the above implementations, by shaping the laser using one or more pairs (e.g., one pair, or two) of cylindrical lenses arranged orthogonally to each other, the adjustment of the spot shape can be more flexible.

In some implementations, the beam shaper can also include at least one of a light-uniformizing plate and a compound-eye lens.

FIG. 5is a structure diagram of an example optical retroreflector in EBI apparatus1as shown inFIGS. 1 and 2.

In some implementations, the optical retroreflector2204includes a prism22042and a second lens22041. For example, the prism22042can include a pyramid prism. In some implementations, the prism22042can be replaced by a combination of multiple mirrors connected in certain angles that forms a semi-closed shape (e.g., a pyramid shape, a cone shape, or a hollow corner cube). For example, the prism22042can be replaced by a hollow corner cube made by a mirror group. The second lens22041can be disposed between the second reflector2203and the prism22042. The second lens22041can also be disposed between the second reflector2203and the test sample. The prism22042can be configured to change a position and an incident angle of the emergent laser that is reflected from the second reflector2203and transmits through the second lens22041, and then transmits the laser back through the second lens22041toward the second reflector2203. The second lens22041can be configured to converge the emergent laser reflected by the second reflector2203toward the optical retroreflector2204to the prism22042. In other words, in the optical retroreflector2204, the second lens22041can focus a divergent reflected laser beam into a parallel beam to be incident on the prism22042and converge the laser beam reflected by the prism22042. The prism22042can reflect the laser beam to the other side of the optical axis of the second lens22041by changing the position and the incident angle of the light beam.

In some implementations, the prism22042can be configured to be symmetric about its optical axis and disposed coaxially with the second lens22041. The prism22042can be configured to reflect the emergent laser reflected thereto from the second reflector2203, symmetrically about its optical axis, back toward the second reflector2203.

In some implementations, the prism22042can also be replaced, for example, by a mirror group, such as a hollow corner cube.

Therefore, according to the above implementations, a retroreflective light path can be added to the laser path to utilize optical energy of the reflected laser, thereby increasing utilization of the laser energy.

In some implementations, the laser to be projected toward the semiconductor device can be projected onto a surface (referred to as a “measurement surface”) of the test sample to be scanned by the e-beam.

According to implementations of this disclosure, the photovoltaic effect can be induced by projecting the laser to the test sample. However, the surface on the test sample where the laser beam is projected is not necessarily limited to be the measurement surface. Alternatively, the laser projected onto the semiconductor device can be projected onto a surface deviated from the measurement surface of the semiconductor device, and the wavelength of the laser can be selected such that the laser penetrates with a sufficient depth within the semiconductor device to induce the photovoltaic effect on the PN junctions near the measurement surface.

Further, in some implementations, the emergent electrons detected by the electron detector130of the EBI device can include at least one type of secondary electrons and backscattered electrons. The secondary electrons can be generated by projecting the incident e-beam onto the test sample.

The implementations of this disclosure can be summarized as follows.

(1) The laser illumination device20of this disclosure is located inside the cavity of the EBI apparatus1, whereby the angle incident on the sample can be smaller, the silicon wafer can absorb more optical energy, the photoelectric effect can be more easily induced, and the utilization of optical energy can be improved.

(2) The laser illumination device20of this disclosure can consist of a laser source210and a guiding device220. The guiding device220can include a beam shaper2201(2201′), a first reflector2202, a second reflector2203, and an optical retroreflector2204. The test sample can be located between the first reflector2202and the second reflector2203.

(3) The laser illumination device20of this disclosure can use the beam shaper2201(2201′) to shape the incident laser beam to achieve the purpose of forming the shape of the laser spot on the test sample to be a predetermined shape.

(4) The laser illumination device20of this disclosure can use an optical retroreflector2204to achieve further utilization of the optical energy of the retroreflected laser, which can improve the utilization of optical energy.

(5) The microlens array-based beam shaper2201of the laser illumination device20of this disclosure can utilize a microlens array-based light-uniformizing system, which can improve the uniformity of laser illumination and the utilization of optical energy.

(6) For the microlens array-based beam shaper2201of the laser illumination device20of this disclosure, different forms of the microlens arrays can cause different shapes of the laser spot, which can facilitate the setting of the laser spot.

(7) For the cylindrical lens-based beam shaper2201′ of the laser illumination device20of this disclosure, focal lengths and a distance between the cylindrical lenses can cause different shapes of the laser spot, which can facilitate the setting of the laser spot.

The benefits of the implementations of this disclosure can be summarized as follows.

This disclosure proposes a method for improving the optical energy utilization and illumination uniformity of laser illumination for inducing a photovoltaic effect in a semiconductor sample during e-beam based defect detection. By designing a specific optical path for beam shaping, the method can alleviate the problem of spot deformation caused by oblique incidence and improve the optical energy in the illumination area. Also, a specific retroreflection path is added to the specific optical path to utilize the optical energy of the reflected laser, which can facilitate fully using the laser energy. Compared with other technical solutions, this disclosure uses a design using an internal optical path. That is, the optical path is entirely located within the cavity of the EBI apparatus, by which the laser beam can be incident on the silicon wafer at a small incident angle. According to the Fresnel formula, when the incident angle of the laser is small, the reflectivity can be low, and the silicon wafer can absorb more optical energy to induce the photovoltaic effect. Two beam shaping solutions are proposed by the implementations of this disclosure. One solution is to use a microlens array for uniformization and light shaping, in which the energy distribution of the laser spot is close to the flat top distribution, and the energy uniformity in the laser spot can be further improved. The other solution is to use two vertically-arranged cylindrical lenses for beam shaping, in which the adjustment of the spot shape can be more flexible.

In another aspect of this disclosure, a laser-assisted e-beam detection method for a semiconductor device is provided. The method can use the aforementioned EBI apparatus to, under the normal working state of the electron detector, simultaneously detects whether an open-circuit defect exists in respective metal contact holes corresponding to the PMOS and the NMOS. The specific content and corresponding technical effects will not be further described hereinafter.

In addition, according to implementations herein, it should be understood that any technical solution as any combination of any two or more of the implementations also falls within the scope of the present disclosure.

It should be understood that orientation terms, such as “up,” “down,” “left,” “right,” and other similar terms, are used to explain the orientation relationship shown in the drawings. These orientation terms are not to be construed as limiting the scope of this disclosure.

The implementations of this disclosure are described in a progressive manner. Description of each implementation focuses on differences from other implementations. The same or similar parts between implementations can be referred to each other.

The word “example” is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “example” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word “example” is intended to present concepts in a concrete fashion. As used in this disclosure, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or” for two or more elements it conjoins. That is, unless specified otherwise, or clear from context, “X includes A or B” is intended to mean any of the natural inclusive permutations. In other words, if X includes A; X includes B; or X includes both A and B, then “X includes A or B” is satisfied under any of the foregoing instances. The term “and/or” used in this disclosure is intended to mean an “and” or an inclusive “or.” That is, unless specified otherwise, or clear from context, “X includes A, B, and/or C” is intended to mean X can include any combinations of A, B, and C. In other words, if X includes A; X includes B; X includes C; X includes both A and B; X includes both B and C; X includes both A and C; or X includes all A, B, and C, then “X includes A and/or B” is satisfied under any of the foregoing instances. Similarly, “X includes at least one of A, B, and C” is intended to be used as an equivalent of “X includes A, B, and/or C.” In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Moreover, use of the term “an aspect” or “one aspect” throughout is not intended to mean the same implementation or aspect unless described as such.

The use of the terms “a” and “an” and “the” and similar referents in the context of describing the disclosure (especially in the context of the following claims) should be construed to cover both the singular and the plural. Furthermore, recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. Finally, the operations of all methods described herein are performable in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the disclosure, and does not pose a limitation on the scope of the disclosure unless otherwise claimed.

It should be understood that although this disclosure uses terms such as first, second, third, etc., the disclosure should not be limited to these terms. These terms are used only to distinguish similar types of information from each other. For example, without departing from the scope of this disclosure, a first information can also be referred to as a second information; and similarly, a second information can also be referred to as a first information. Depending on the context, the words “if” as used herein can be interpreted as “when,” “while,” or “in response to.”