Apparatus, method and cutting apparatus for determining head and tail of a crystal rod segment

Abstract

An embodiment of the present invention discloses an apparatus, method, and cutting device for determining the head and tail of a crystal rod segment. The apparatus includes: a resistance measuring unit, which is used to measure a first end resistance value of a first end of the crystal rod segment and a second end resistance value of a second end of the crystal rod segment; and a determination unit, which is used to determine that the end corresponding to the larger one of the first end resistance value and the second end resistance value is the head of the crystal rod segment and that the end corresponding to the smaller one of the first end resistance value and the second end resistance value is the tail of the crystal rod segment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor wafer production, and in particular to a device and method for determining the head and tail of a segment of a crystal bar, and a cutting apparatus. BACKGROUND

[0002] In the production of semiconductor wafers, a crystal bar produced by the Czochralski method is first cut into a plurality of segments, each of which is then cut into a thin initial wafer by, for example, multi-wire slicing, and the initial wafer is then subjected to grinding, polishing, and possibly epitaxy, to obtain a finished wafer.

[0003] For a crystal bar produced by the Czochralski method, the crystal bar is gradually formed in a very slow manner, with the portion formed first in time being referred to as the head of the crystal bar, and the portion formed later in time being referred to as the tail of the crystal bar. On the other hand, the characteristics of the head and tail of the crystal bar are different due to changes in the crystal pulling environment over time, and therefore the head and tail of the crystal bar and the corresponding head and tail of the plurality of segments need to be identified in order to facilitate subsequent processing operations and analysis.

[0004] In the prior art, the head and tail of the plurality of segments are identified by providing markings on the crystal bar. However, in this approach, the distance between the two markings can be unreasonable, resulting in the absence of the two markings on a single segment, or the markings can be lost during the cutting process, again resulting in the absence of the two markings on a single segment. This results in the head and tail of the segment being unable to be identified or being incorrectly identified, which affects subsequent processing operations and analysis. SUMMARY

[0005] To address the above technical problems, embodiments of the present application provide a device and method for determining the head and tail of a segment of a crystal bar, and a cutting apparatus, which can identify the head and tail of each segment after the crystal bar has been cut into a plurality of segments, thereby avoiding affecting subsequent processing operations and analysis.

[0006] The technical solution of the present application is as follows:

[0007] In a first aspect, embodiments of the present application provide a determination device for determining the head and tail of a segment of a crystal bar, the determination device comprising:

[0008] a resistance measuring unit for measuring a first end resistance value of a first end of the ingot segment and a second end resistance value of a second end of the ingot segment;

[0009] a determination unit for determining an end corresponding to a larger one of the first end resistance value and the second end resistance value as a head of the ingot segment and an end corresponding to a smaller one of the first end resistance value and the second end resistance value as a tail of the ingot segment.

[0010] In a preferred embodiment, the judging device further comprises:

[0011] a conveying unit for conveying the ingot segment;

[0012] an end recognizing unit for determining that the first end and the second end of the ingot segment are at a set position during conveying of the ingot segment so as to measure the first end and the second end of the ingot segment.

[0013] In a preferred embodiment, the end recognizing unit comprises:

[0014] a signal emitter for emitting a signal;

[0015] a signal receiver for receiving the signal emitted by the signal emitter;

[0016] wherein the conveying unit conveys the ingot segment to block a propagation path of the signal so that the end recognizing unit determines that one end of the ingot segment is at the propagation path at a time when the signal receiver changes from being able to receive the signal to being unable to receive the signal, and the end recognizing unit determines that another end of the ingot segment is at the propagation path at a time when the signal receiver changes from being unable to receive the signal to being able to receive the signal.

[0017] In a preferred embodiment, the resistance measuring unit is a four-probe resistance meter.

[0018] In a second aspect, an embodiment of the present application provides a judging method for judging a head and a tail of an ingot segment, the judging method comprising:

[0019] measuring a first end resistance value of a first end of the ingot segment and a second end resistance value of a second end of the ingot segment;

[0020] determining one end of the crystal bar segment as a head of the crystal bar segment and the other end of the crystal bar segment as a tail of the crystal bar segment.

[0021] In a preferred embodiment, the determining method further comprises:

[0022] transporting the crystal bar segment;

[0023] determining that an end of the crystal bar segment is at a set position during the transporting of the crystal bar segment, so as to measure the end of the crystal bar segment.

[0024] In a preferred embodiment, the determining that an end of the crystal bar segment is at a set position during the transporting of the crystal bar segment comprises:

[0025] emitting a signal by a signal emitter;

[0026] receiving the signal emitted by the signal emitter by a signal receiver;

[0027] wherein the crystal bar segment is transported to block a propagation path of the signal, so as to determine that one end of the crystal bar segment is at the propagation path at a moment when the signal receiver changes from being able to receive the signal to being unable to receive the signal, and to determine that the other end of the crystal bar segment is at the propagation path at a moment when the signal receiver changes from being unable to receive the signal to being able to receive the signal.

[0028] In a third aspect, an embodiment of the present application provides a cutting device for cutting a whole crystal bar into at least two crystal bar segments, the cutting device comprising the determining apparatus according to the first aspect.

[0029] In a preferred embodiment, the cutting device further comprises:

[0030] a cutting apparatus for cutting the crystal bar;

[0031] a transporting apparatus for transporting the crystal bar to the cutting apparatus and transporting the at least two crystal bar segments away from the cutting apparatus;

[0032] wherein the determining apparatus is arranged downstream of the cutting apparatus in a transporting direction of the transporting apparatus.

[0033] In a preferred embodiment, the transporting apparatus comprises a carrier for carrying the crystal bar and the at least two crystal bar segments, a cross section of the carrier being V-shaped.

[0034] The embodiments of the present application provide a device, a method and a cutting-off apparatus for determining the head and tail of a crystal rod segment, even if the two marks for marking the head and tail are not present on the single crystal rod segment due to unreasonable setting distance of the two marks, or the two marks for marking the head and tail are not present on the single crystal rod segment due to the cutting process, and the orientation of the crystal rod segment in the crystal rod cannot be obtained, the head and tail of the crystal rod segment can still be determined by measuring the resistance of the two ends of the crystal rod segment, thereby facilitating the operation and analysis of the subsequent processing process. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 An illustrative schematic diagram of a crystal rod drawn by a Czochralski method and the crystal rod being cut into a plurality of crystal rod segments is shown;

[0036] Figure 2 A schematic diagram of a determination device for determining the head and tail of a crystal rod segment according to an embodiment of the present application is shown;

[0037] Figure 3 A schematic diagram of a determination device for determining the head and tail of a crystal rod segment according to another embodiment of the present application is shown;

[0038] Figure 4 A schematic diagram of a determination device for determining the head and tail of a crystal rod segment according to another embodiment of the present application is shown;

[0039] Figure 5 A schematic diagram of a determination method for determining the head and tail of a crystal rod segment according to an embodiment of the present application is shown;

[0040] Figure 6 A schematic diagram of a cutting-off apparatus according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.

[0042] Firstly, refer to Figure 1 which shows a whole crystal rod R drawn by a Czochralski method for example. In order to facilitate the subsequent operation such as multi-wire cutting, the crystal rod R needs to be divided into a plurality of crystal rod segments RS with the same length or different lengths, as shown in Figure 1 which schematically shows that the crystal rod R is divided into a plurality of crystal rod segments RS with different lengths by an elliptical cross section, which can be realized by a cutting-off apparatus described in detail below.

[0043] For a whole crystal bar R pulled out by a Czochralski method, for example, its head and tail are very easy to be identified, for example, by the shape of the two ends of the crystal bar R, because the head and tail of the crystal bar R thus obtained are very different in shape, so that, for example, when the position of the head and tail of the crystal bar R relative to a cutting device needs to be ensured before the crystal bar R is cut by the cutting device, or when the head or tail of the crystal bar R needs to be cut first, it is easy to achieve. However, for a plurality of crystal bar segments RS cut from the crystal bar R, see Figure 1 It is easy to understand that the corresponding head and tail (the end adjacent to the head of the whole crystal bar R is the head, and the end adjacent to the tail of the whole crystal bar R is the tail) cannot be identified by shape, for example Figure 1 Two crystal bar segments with reference sign RS are indicated in the figure, so that, in the case that the crystal bar segments RS are separated from the crystal bar R, or in the case that the position of the crystal bar segments RS in the crystal bar R is unknown before the crystal bar R is cut, for example, when the plurality of crystal bar segments RS cut are mixed together in an unknown manner, the corresponding head and tail of the crystal bar segments RS cannot be identified, resulting in that, in the subsequent processing of the crystal bar segments RS, for example, when the head and tail of the crystal bar segments RS need to be identified in order to adopt a targeted processing technology, the head of the crystal bar segments RS is mistakenly regarded as the tail and the tail of the crystal bar segments RS is mistakenly regarded as the head, thereby causing a mismatch of the processing technology, and further causing the product to be unqualified or scrapped.

[0044] The purpose of the embodiments of the present application is to enable the head and tail of the crystal bar segments RS to be distinguished even if, for example, the plurality of crystal bar segments RS cut are mixed together in an unknown manner after the whole crystal bar R is cut into a plurality of crystal bar segments RS.

[0045] It is considered that, for a whole crystal bar R pulled out by a Czochralski method, for example, the characteristics in the longitudinal direction thereof are different and the change trend of the characteristics is single, based on which, see Figure 2 The embodiments of the present application provide a judging device 10 for judging the head and tail of a crystal bar segment RS, which can include:

[0046] A resistance measuring unit 11 for measuring a first end resistance value R1 of a first end E1 of the crystal bar segment RS and a second end resistance value R2 of a second end E2 of the crystal bar segment RS;

[0047] a determination unit 12 for determining the end corresponding to the larger one of the first end resistance value R1 and the second end resistance value R2 as the head of the ingot segment RS and determining the end corresponding to the smaller one of the first end resistance value R1 and the second end resistance value R2 as the tail of the ingot segment RS, as shown in Figure 1 Fig. 1. In the case where the first end resistance value R1 of the first end E1 is larger than the second end resistance value R2 of the second end E2, then the first end E1 is the head of the ingot segment RS and the second end E2 is the tail of the ingot segment RS, while in the case where the first end resistance value R1 of the first end E1 is smaller than the second end resistance value R2 of the second end E2, then the first end E1 is the tail of the ingot segment RS and the second end E2 is the head of the ingot segment RS.

[0048] For a crystal bar R pulled by a Czochralski method, changes in the pulling environment or the pulling process parameters over time result in different resistances of the head and the tail of the crystal bar R, and the resistance in the longitudinal direction of the crystal bar R always gradually decreases from the head to the tail regardless of the changes in the environment or the pulling process parameters, so that the head and the tail of the ingot segment RS can be determined by measuring the resistances of the two ends of the ingot segment RS.

[0049] In the above-described determination device 10 according to the embodiment of the present application, even if the case where the two marks for marking the head and the tail do not exist on the single ingot segment RS due to unreasonable setting distance of the two marks for marking the head and the tail, or the case where the two marks for marking the head and the tail disappear due to the cutting process and thus do not exist on the single ingot segment RS, and the case where the orientation of the ingot segment RS in the crystal bar R cannot be obtained, the head and the tail of the ingot segment RS can still be determined by measuring the resistances of the two ends of the ingot segment RS, thereby facilitating the operation and analysis of the subsequent process.

[0050] Referring to Figure 2 It can be understood that, since the resistance measuring unit 11 needs to measure the two ends of the ingot segment RS, relative movement between the resistance measuring unit 11 and the ingot segment RS must be generated to enable the resistance measuring unit 11 to be opposite to the two ends of the ingot segment RS respectively, and in this case, it is also necessary to know that the resistance measuring unit 11 is at the positions opposite to the two ends of the ingot segment RS respectively during the relative movement. For this purpose, in the preferred embodiment of the present application, referring to Figure 3 , the determination device 10 can further include:

[0051] a transport unit 13 for transporting the ingot segment RS, for example along Figure 3 in the direction indicated by the arrow, from a position indicated by the dashed line to a position indicated by the solid line;

[0052] an end recognition unit 14 for determining that the first end E1 and the second end E2 of the ingot segment RS are at a set position during the transport of the ingot segment RS, in order to measure the first end E1 and the second end E2 of the ingot segment RS. The set position here can be a position in which the end of the ingot segment RS is directly opposite the resistance measurement unit 11 so that the resistance measurement unit 11 can measure the end of the ingot segment RS, or a position in which the end of the ingot segment RS is not directly opposite the resistance measurement unit 11, but is determined according to a time-displacement function during the transport, for example, that the end of the ingot segment RS is directly opposite the resistance measurement unit 11 so that the resistance measurement unit 11 can measure the end of the ingot segment RS after a certain time has elapsed.

[0053] In the above-described embodiments according to the application, for example, the resistance measurement unit 11 can be fixed and the ingot segment RS can be moved relative to the resistance measurement unit 11, thereby simplifying the manner in which the relative movement between the resistance measurement unit 11 and the ingot segment RS is produced, for example, both ends of each ingot segment RS can be brought opposite the resistance measurement unit 11 for measurement while the cutting device cuts the ingot R into ingot segments RS and transports the ingot segments RS, or the transport unit 13 here can be part of the transport device of the cutting device, thereby reducing the number of components and saving costs.

[0054] The implementation of the above-described end recognition unit 14 is very diverse, and in the preferred embodiments of the application, see Figure 4 , the end recognition unit 14 can comprise:

[0055] a signal transmitter 141 for transmitting a signal S;

[0056] a signal receiver 142 for receiving the signal S transmitted by the signal transmitter 141;

[0057] wherein the transport unit 13 transports the ingot segment RS so as to block the propagation path P of the signal S, so that the end recognition unit 14 determines that the signal receiver 142 changes from being able to receive the signal S to being unable to receive the signal S at the moment when the first end E1 and the second end E2 of the ingot segment RS are at the set position, for example, when Figure 4As shown in FIG. 1, when the crystal bar segment RS is at the position shown by the dashed line, it is determined that one end of the crystal bar segment RS is at the propagation path P. It is easy to understand that, when the crystal bar segment RS is at the position shown by the solid line, Figure 4 As shown in FIG. 1, when the crystal bar segment RS is at the position shown by the dashed line, it is determined that one end of the crystal bar segment RS is at the propagation path P. It is easy to understand that, when the crystal bar segment RS is at the position shown by the solid line, Figure 4 As shown in FIG. 1, when the crystal bar segment RS is at the position shown by the dashed line, it is determined that one end of the crystal bar segment RS is at the propagation path P. It is easy to understand that, when the crystal bar segment RS is at the position shown by the solid line, Figure 4 As shown in FIG. 1, when the crystal bar segment RS is at the position shown by the dashed line, it is determined that one end of the crystal bar segment RS is at the propagation path P. It is easy to understand that, when the crystal bar segment RS is at the position shown by the solid line,

[0058] For the resistance measuring unit 11 described above, in the preferred embodiment of the present application, the resistance measuring unit 11 can be a four-probe resistance meter. The four-probe resistance meter is an instrument for measuring the resistance of a substance, and the main machine adopts advanced circuit design, the measured value is more accurate, faster and more accurate, the screen adopts liquid crystal display, matches the computer interface and software, and can make the operation simple and clear.

[0059] Referring to Figure 5 and in combination with Figure 2 The embodiment of the present application also provides a judgment method for judging the head and tail of a crystal bar segment RS, which can include the following steps.

[0060] S501: measuring a first end resistance value R1 of a first end E1 of the crystal bar segment RS and a second end resistance value R2 of a second end E2 of the crystal bar segment RS;

[0061] S502: determining the end corresponding to the larger one of the first end resistance value R1 and the second end resistance value R2 as the head of the crystal bar segment RS and determining the end corresponding to the smaller one of the first end resistance value R1 and the second end resistance value R2 as the tail of the crystal bar segment RS.

[0062] As described above, for a crystal bar R drawn by, for example, the Czochralski method, changes in the crystal drawing environment or crystal drawing process parameters over time result in different resistances of the head and tail of the crystal bar R, and the resistance in the longitudinal direction of the crystal bar R always gradually decreases from the head to the tail regardless of changes in the environment or crystal drawing process parameters, so the head and tail of the crystal bar segment RS can be judged by measuring the resistances of the two ends of the crystal bar segment RS.

[0063] In the above-mentioned judgment method according to an embodiment of the present invention, even if the setting distance between the two marks for marking the head and the tail is unreasonable and there are no two marks for marking the head and the tail on the cut single crystal rod segment RS, or the marks disappear due to the cutting process and there are no two marks for marking the head and the tail on the single crystal rod segment RS, and when the orientation of the crystal rod segment RS in the crystal rod R cannot be obtained, the head and the tail of the crystal rod segment RS can still be judged by measuring the resistance of the two ends of the crystal rod segment RS, thereby facilitating the operation and analysis of subsequent processing processes.

[0064] In the above embodiment, since it is necessary to measure the two ends of the crystal rod segment RS, it is necessary to generate relative movement between the component for measuring resistance and the crystal rod segment RS so that the component is respectively opposite to the two ends of the crystal rod segment RS. In this case, it is also necessary to know during the relative movement that the component is at a position respectively opposite to the two ends of the crystal rod segment RS. In this regard, in a preferred embodiment of the present invention, Figure 3 , the judgment method may further include:

[0065] transporting the crystal rod segment RS;

[0066] During the transportation of the crystal ingot segment RS, it is determined that the first end E1 and the second end E2 of the crystal ingot segment RS are at a set position so as to measure the first end E1 and the second end E2 of the crystal ingot segment RS. Similarly, the set position here can be the end of the crystal ingot segment RS directly touching the first end E1 and the second end E2 of the crystal ingot segment RS. Figure 3 The position of the component for measuring resistance, such as the resistance measuring unit 11, shown in the figure, is relative to such that the component can measure the end of the crystal rod segment RS. It can also be a position where the end of the crystal rod segment RS is not directly opposite to the component, but is determined according to, for example, a time-displacement function during the transportation process, such that the end of the crystal rod segment RS is directly opposite to the component after a specific time has passed, so that the component can measure the end of the crystal rod segment RS.

[0067] In a preferred embodiment of the present invention, Figure 4 The step of determining that the end of the crystal ingot segment RS is at a set position during the transportation of the crystal ingot segment RS may include:

[0068] Using the signal transmitter 141 to transmit the signal S;

[0069] Utilizing the signal receiver 142 to receive the signal S transmitted by the signal transmitter 141;

[0070] wherein the segment RS of the crystal bar is transported so as to obstruct the propagation path P of the signal S so that at the moment when the signal receiver 142 changes from being able to receive the signal S to being unable to receive the signal S, for example at the moment when the segment RS of the crystal bar is in the position shown in dashed line in Figure 4 it is determined that one end of the segment RS of the crystal bar is at the propagation path P, it is readily understood that in the case where the propagation path P is a straight line, as specifically shown in Figure 4 it can be directly determined that one end of the segment RS of the crystal bar is at the connecting straight line between the signal transmitter 141 and the signal receiver 142, and at the moment when the signal receiver 142 changes from being unable to receive the signal S to being able to receive the signal S, for example at the moment when the segment RS of the crystal bar is in the position shown in solid line in Figure 4 it is determined that the other end of the segment RS of the crystal bar is at the propagation path P, it is also readily understood that in the case where the propagation path P is a straight line, as specifically shown in Figure 4 it can be directly determined that the other end of the segment RS of the crystal bar is at the connecting straight line between the signal transmitter 141 and the signal receiver 142.

[0071] Referring to Figure 6 , the present application also provides a cutting-off apparatus 1 for cutting a whole crystal bar R into at least two segments RS of crystal bar, which can comprise the judging device 10 according to the embodiments of the present application.

[0072] Preferably, referring to Figure 6 , the cutting-off apparatus 1 can further comprise:

[0073] a cutting device 20 for cutting the crystal bar R, specifically, the cutting device 20 can be a device comprising a band saw or a device comprising a cutting wire, so as to complete the cutting in a band saw cutting or wire cutting manner;

[0074] a conveying device 30 for conveying the crystal bar R to the cutting device 20 and conveying the at least two segments RS of crystal bar away from the cutting device 20, specifically, this can be achieved by moving the carrier 31 of the conveying device 30 for carrying the crystal bar R and the at least two segments RS of crystal bar in opposite directions to each other, as schematically shown by the bidirectional arrow in Figure 6 ;

[0075] wherein in the conveying direction of the conveying device 30, the judging device 10 is arranged downstream of the cutting device 20, in Figure 6When the carrier 31 shown in the figure moves in opposite directions to each other, the conveying direction is turned by 180°, that is, after the ingot R is cut into the at least two ingot segments RS, the judging device 10 judges the head and tail of the ingot segment RS.

[0076] Preferably, the conveying device 30 is also used to realize the function of the conveying unit 13. That is, the conveying device 30 and the conveying unit 13 are not two independent components, and the conveying unit 13 is only a part of the conveying device 30, so that the number of components can be reduced and the cost can be saved.

[0077] Preferably, the cross section of the carrier 31 can be V-shaped to avoid the rolling of the ingot R or the ingot segment RC.

[0078] It should be noted that the technical solutions described in the embodiments of the present application can be combined arbitrarily without conflict.

[0079] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A device for determining the head and tail of a crystal rod segment, characterized in that: The judging device comprises: a resistance measuring unit, configured to measure a first end resistance value of a first end of the crystal ingot segment and a second end resistance value of a second end of the crystal ingot segment; a determination unit configured to determine that the end corresponding to the larger one of the first end resistance value and the second end resistance value is the head of the crystal ingot segment and to determine that the end corresponding to the smaller one of the first end resistance value and the second end resistance value is the tail of the crystal ingot segment, Wherein, the judging device further includes: a conveying unit, the conveying unit being used to convey the crystal ingot segments; an end recognition unit, configured to determine that the first end and the second end of the crystal ingot segment are at set positions during the transport of the crystal ingot segment, so as to measure the first end and the second end of the crystal ingot segment; Wherein, the end identification unit includes: A signal transmitter, wherein the signal transmitter is used to transmit a signal; a signal receiver, configured to receive the signal transmitted by the signal transmitter; The conveying unit conveys the crystal rod segment to block the propagation path of the signal, so that the end identification unit determines that one end of the crystal rod segment is at the propagation path when the signal receiver changes from being able to receive the signal to being unable to receive the signal, and the end identification unit determines that the other end of the crystal rod segment is at the propagation path when the signal receiver changes from being unable to receive the signal to being able to receive the signal.

2. The judgment device according to claim 1, wherein: The resistance measuring unit is a four-probe resistance meter.

3. A method for determining the head and tail of a crystal rod segment, characterized in that: The judgment method includes: measuring a first end resistance value of a first end of the crystal ingot segment and a second end resistance value of a second end of the crystal ingot segment; The end corresponding to the larger one of the first end resistance value and the second end resistance value is determined as the head of the crystal ingot segment, and the end corresponding to the smaller one of the first end resistance value and the second end resistance value is determined as the tail of the crystal ingot segment. The judgment method further includes: transporting the crystal rod segment; determining that the end of the crystal ingot segment is at a set position during the transportation of the crystal ingot segment so as to measure the end of the crystal ingot segment; The step of determining that the end of the crystal ingot segment is at a set position during the crystal ingot segment is being transported includes: Transmitting a signal using a signal transmitter; Receiving the signal transmitted by the signal transmitter using a signal receiver; The crystal rod segment is transported to block the propagation path of the signal, so that when the signal receiver changes from being able to receive the signal to being unable to receive the signal, one end of the crystal rod segment is determined to be at the propagation path, and when the signal receiver changes from being unable to receive the signal to being able to receive the signal, the other end of the crystal rod segment is determined to be at the propagation path.

4. A cutting device for cutting a whole crystal rod into at least two crystal rod segments, characterized in that: The interception device comprises the judgment device according to claim 1 or 2.

5. The cutting device according to claim 4, characterized in that The interception device also includes: a cutting device, the cutting device being used to cut the crystal rod; a conveying device, the conveying device being used to convey the crystal ingot to the cutting device and to convey the at least two crystal ingot segments away from the cutting device; Wherein, in the conveying direction of the conveying device, the judging device is arranged downstream of the cutting device.

6. The cutting device according to claim 5, characterized in that The conveying device includes a carrier for carrying the crystal ingot and the at least two crystal ingot segments, and a cross section of the carrier is V-shaped.

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