Multi-row carrier cassette for semiconductor wafers

Abstract

A carrier cassette for wafers comprises: two side plates which are mutually opposite in a first direction and each of which has a locking slot on a top side thereof; at least one lower holding rod which is attached between the two mutually opposite side plates; and at least two side holding rods which are mutually opposite in a second direction and which are attached between the two mutually opposite side plates; and an upper locking rod which can be locked in the locking slots of the mutually opposite side plates in order to hold down wafers in the carrier cassette. The side plates, the at least one lower holding rod, the at least two side holding rods and the upper locking rod delimit two receiving regions for two rows of wafers, said rows extending in the first direction, and the two receiving regions being mutually adjacent in the second direction. The upper locking rod is designed to hold down the two rows of wafers and has protrusions, each protrusion being designed to separate associated wafers of the two rows, said wafers being adjacent to one another in the first direction, from one another when the upper locking rod is locked in the locking slots.

Description

[0001] Multi-row carrier cassette for semiconductor wafers

[0002] Description

[0003] The present invention relates to carrier cassettes for semiconductor wafers, and in particular to carrier cassettes for semiconductor wafers that enable the treatment of semiconductor wafers in batch mode. Such wafer carriers, typically also referred to as baskets or carriers, are used to place multiple wafers in a tank in batch mode and treat them there with a treatment liquid.

[0004] Various carrier cassettes are known from the state of the art.

[0005] For example, DE 20 2015 104 876 U1 discloses a substrate carrier for solar cells, which has two opposing side plates, between which side rods and base rods are arranged. Notches are provided on the upper side of the side plates, into which a pressure rod can be inserted and locked by rotating the pressure rod. The side rods and base rods each have teeth by which adjacent wafers arranged between the side plates can be separated from each other. The substrate carrier is designed to accommodate a row of wafers between the two side plates and to hold them in place by locking the pressure rod in the notches.

[0006] From DE 10 2015 224980 B4, a cassette for holding plate-shaped elements is known, which is also designed to hold a row of wafers between two side plates, and which is shown in Fig. 12a of the present application. The cassette has two side plates 2, 4, between which six receiving rods or racks 6 are arranged. The racks 6 are firmly connected to the side plates 2 and 4. A locking bar is also designed as a rack. The locking bar 8 can be locked in engagement sections 10 which are formed in the upper sides of the side plates 2, 4. Each engagement section 10 has two grooves into which pins of the locking bar fit, so that the locking bar can be locked in the engagement sections. The side plates 2 and 4 also have hooks / receiving means 12 in their upper sides, which enable the insertion or removal of the wafers.enable removal of the cassette, for example, from a tank. EP4 1 13 586 A1 discloses a wafer carrier that also has two opposing side plates and support rods mounted between the opposing side plates. The side walls each have at least one groove for receiving at least one movable support rod. Thus, two wafers can be arranged one above the other in the wafer carrier, with the at least one movable support rod being arranged between the two wafers.

[0007] A simplified schematic cross-sectional view of a carrier cassette similar to that shown in Fig. 12a is shown in Fig. 12b. As schematically illustrated in Fig. 12b, the bars 6 and 8 of the basket have elements in the form of projections 16 that prevent mutual contact between adjacent wafers, such a wafer 20 being shown in Fig. 12b. The locking bar 8 serves to prevent the wafer 20 from emerging upwards from the carrier cassette. The locking bar 8, which can also be referred to as a hold-down device or pressure bar, is not permanently mechanically bound to the basket, but is lockable in the mechanism 10. A carrier cassette as shown in Figs. 12a and 12b has only one receiving area for wafers arranged one behind the other, which area is closed by the locking bar 8. The carrier cassette is designed in particular for processing square wafers.

[0008] The production of solar cells requires various treatments of wafers, especially silicon wafers, including etching, cleaning, and drying. Carrier cassettes must be designed in such a way that the wafers do not touch each other during the treatment steps, as this could lead to surface inhomogeneities. Furthermore, buoyancy of the wafers due to reactions and reaction products occurring during etching processes must be prevented, as this could lead to a loss of wafers from the carrier cassette and / or undesired mutual contact between the wafers.

[0009] A significant issue in the solar industry is cost pressure. Reducing wafer thickness is a key factor in lowering the cost of solar modules, particularly the cost per watt. The thinner the wafers, the cheaper they become due to a corresponding reduction in the silicon material. The trend is towards using material with a thickness of less than 100 pm, although the current standard thickness of M12 / G 12 wafers is between 170 and 150 pm. One limitation arises during wet-chemical treatment. The thinner the wafers, the more they tend to stick together during the process, meaning the greater the distance between wafers (pitch distance) in the carrier cassette must be to prevent sticking.The larger the pitch distance, the fewer wafers fit in a carrier cassette and the smaller the throughput of a treatment machine, which ultimately leads to higher costs.

[0010] During wet-chemical processing, the wafer support on the rods or the spacers in the form of the rod protrusions can cause shadows on the wafers, also known as carrier marks, which are caused by flow during the etching process. These shadows are visible after the wet-chemical treatment and are often considered a cosmetic defect, which can lead to problems with satisfaction and machine acceptance.

[0011] The object of the present invention is to provide alternative carrier cassettes for wafers that enable increased throughput at reduced wafer costs, as well as to provide methods for using carrier cassettes and methods for processing wafers.

[0012] This object is achieved by a carrier cassette according to claim 1 and methods according to claims 17 and 18. Further developments of the invention are set out in the dependent claims.

[0013] According to embodiments, a carrier cassette for wafers has the following features: two side plates opposite one another in a first direction, each of which has a locking groove on an upper side thereof, at least one lower holding rod mounted between the two opposite side plates, at least two lateral holding rods opposite one another in a second direction, which are mounted between the two opposite side plates, and an upper locking rod that can be locked in the locking grooves of the opposite side plates in order to hold down wafers in the carrier cassette. The side plates, the lower holding rod, the at least two lateral holding rods and the upper locking bar define two receiving areas for two rows of wafers extending in the first direction, wherein the two receiving areas are arranged next to one another in the second direction.The upper locking bar is configured to hold down the two rows of wafers and has projections configured to separate adjacent wafers of both rows from each other in the first direction when the upper locking bar is locked in the locking grooves.

[0014] According to the invention, two receiving areas for two rows of wafers are provided horizontally next to each other in the carrier cassette, which makes it possible to provide a common upper locking bar for both receiving areas. This enables a simple construction of a carrier cassette in which two adjacent rows of wafers can be held in the carrier cassette by a common locking bar during treatments such as those required in the manufacture of solar cells, such as etching, cleaning, or drying. The projections in the locking bar prevent the wafers from touching each other during the treatment steps, thus preventing inhomogeneities on the surface.

[0015] In embodiments, the projections of the locking bar can have a first row of projections configured to separate adjacent wafers of one of the two rows from one another in the first direction, and a second row of projections configured to separate adjacent wafers of the other of the two rows from one another in the first direction. The projections of the first row of projections can extend at a first angle from the upper locking bar, and the projections of the second row of projections can extend at a second angle from the upper locking bar. Providing separate rows of projections for the individual rows of wafers makes it possible to reduce the material required for the projections and prevent mutual contact between adjacent wafers of both rows.

[0016] In embodiments, the projections may comprise a series of projections, each of which is configured to separate adjacent wafers of both rows from each other in the first direction. In such embodiments, the locking bar may have a simple structure while simultaneously preventing mutual contact between adjacent wafers in the two horizontally adjacent rows.

[0017] In embodiments, the carrier cassette further comprises means for separating the two receiving areas from one another in the second direction. Such means can be provided in addition to the holding rod. The separating means can delimit the first receiving area and the second receiving area on the sides facing one another. In embodiments, the means for separating the two receiving areas comprise a central holding rod that is mounted between the side plates and separates the two receiving areas from one another in the second direction. In such examples, the central holding rod can have projections for separating wafers of the two rows of wafers that are adjacent in the first direction from one another. Such embodiments make it possible to hold the wafers stably within the two receiving areas because rods can be provided that delimit the respective receiving area on all four sides.

[0018] In embodiments, the lower support rod can have a continuous or discontinuous web designed to separate adjacent wafers from one another in the second direction. The web represents the means for separating the two receiving areas in the second direction. In other words, the lower support rod can have the means for separating the wafers of the two horizontally adjacent wafer rows from one another. This reliably prevents contact between wafers in the first row and wafers in the second row.

[0019] In some embodiments, the lower support rod is configured to delimit both receiving areas at the bottom. Such examples enable a carrier cassette with a simple structure, since only one lower support rod is required.

[0020] In embodiments, the carrier cassette may have two lower support rods mounted between the two opposite side plates, each of which defines one of the two receiving areas at the bottom. In such examples, the stability of the wafers held in the receiving areas may be increased.

[0021] In embodiments, the at least two lateral holding rods and / or the at least one lower holding rod can have projections that are designed to separate adjacent wafers from one another in the first direction. In embodiments in which a lower holding rod is provided for both rows of wafers, this holding rod can have projections that are designed to separate adjacent wafers of both rows from one another in the first direction, for example by means of projections extending in different directions or by means of projections that are designed to separate adjacent wafers of both rows from one another in the first direction. Embodiments thus make it possible to increase the reliability with which adjacent wafers are prevented from touching one another.

[0022] Embodiments enable the processing of cut wafers by closing two receiving areas for the wafers in the carrier cassette by the locking bar. In embodiments, a dimension of the two receiving areas in one direction between the at least one lower holding bar and the locking bar is twice as large as a dimension of the two receiving areas in the second direction. Embodiments thus enable the processing of halved wafers side by side in a carrier cassette.

[0023] Embodiments enable the processing of wafers with a smaller surface area, allowing wafer thickness to be reduced, for example, to a thickness of less than 100 μm with a small pitch of less than 5 μm, without the risk of adjacent wafers touching or sticking together. This can enable a throughput of up to 18,400 wafers per hour (wph) in embodiments.

[0024] Furthermore, embodiments allow for a reduction in the wafer support positions in the carrier cassette. Typical standard M12 / G12 carrier cassettes have nine rods, resulting in nine support points and correspondingly nine carrier marks. Embodiments allow for a reduction to four to eight rods, which reduces the support points and carrier marks accordingly.

[0025] By enabling the processing of thinner wafers and also adjacent rows of wafers, embodiments of the invention enable an increase in throughput when processing sliced ​​wafers using a carrier cassette. Only one locking bar is required to vertically delimit two receiving sections, or treatment chambers, in a carrier cassette. This simplifies automation and material usage.

[0026] In embodiments, the carrier cassette can have more than two receiving areas arranged next to one another in the horizontal direction.In embodiments, the carrier cassette has a plurality of upper locking bars and the side plates each have a plurality of locking grooves, wherein the side plates, the lower holding bar, the at least two lateral holding bars and the plurality of upper locking bars delimit more than two receiving areas for more than two rows of wafers extending in the first direction, wherein the more than two receiving areas are arranged next to one another in the second direction and wherein each of the upper locking bars is designed to hold down two rows of wafers that are adjacent in the second direction, and wherein each of the upper locking bars has projections that are designed to separate wafers of the two rows that are adjacent in the first direction from one another when the upper locking bar is locked in two respective ones of the locking grooves.Embodiments thus enable a further increase in throughput by designing the carrier cassette to accommodate more than two rows of wafers arranged side by side in the horizontal direction.

[0027] In embodiments, the respective projections of the locking bar and / or the support rods are configured to position rows of wafers with a thickness of <160 μm, preferably <100 μm, with a distance of <7 mm, preferably <5 mm, between wafers in the first direction in the receiving areas. Embodiments thus enable increased throughput due to the ability to process thin wafers with a small distance between them.

[0028] In some embodiments, the side plates have receiving means on the upper side for mechanical handling of the carrier cassettes. Some embodiments thus enable automated production of wafers for solar cells by means of a wet-chemical treatment of halved or multiply cut semiconductor wafers, such as silicon wafers.

[0029] In embodiments, the carrier cassettes are designed to process wafers in batch mode. The wafers can be semiconductor wafers, for example, silicon wafers. The wafers can be halved or multiply cut wafers. In embodiments, the wafers can be rectangular wafers obtained by halving square wafers, with one side being twice as long as the other side. In embodiments, the carrier cassettes or receiving areas thereof are designed to receive two rows of such wafers edgewise next to one another.

[0030] Embodiments relate to the use of such carrier cassettes, in particular for treating wafers with a treatment liquid in batch operation, wherein two rows of wafers are placed next to one another in the carrier cassette. Embodiments provide methods for treating wafers with a treatment liquid using a carrier cassette as described herein, comprising the following steps: placing two rows of wafers next to one another in the carrier cassette; locking the upper locking bar in the locking grooves in order to hold down the two rows of wafers with the locking bar; and placing the carrier cassette with the wafers into a bath containing the treatment liquid in order to subject the wafers to treatment with the treatment liquid.

[0031] Short description of the drawings

[0032] Examples of the invention are explained in more detail below with reference to the accompanying drawings. They show:

[0033] Fig. 1 is a schematic representation of an embodiment of a carrier cassette according to the invention;

[0034] Fig. 2 to 5 are schematic cross-sectional views of embodiments of carrier cassettes according to the invention;

[0035] Fig. 6a to 6c are schematic representations of embodiments of upper locking bars;

[0036] Fig. 7a to 7c are schematic representations for explaining an embodiment of a carrier cassette according to the invention;

[0037] Fig. 8a and 8b are schematic representations for explaining a configuration of an embodiment of a lower support rod;

[0038] Fig. 9 is a schematic diagram to explain an embodiment with more than two rows of wafers arranged next to one another;

[0039] Fig. 10a to 10c are schematic representations for explaining embodiments of central support rods; Fig. 11 is a schematic representation for explaining an embodiment with more than two horizontal rows of wafers arranged side by side; and

[0040] Fig. 12a and 12b are an isometric view and a schematic cross-sectional view of a known carrier cassette.

[0041] Examples of the present invention are described in detail below with the use of the accompanying drawings. It should be noted that like elements or elements having the same functionality are provided with the same or similar reference numerals, and repeated description of elements provided with the same or similar reference numerals is typically omitted. Descriptions of elements having the same or similar reference numerals may be interchangeable. In the following description, many details are described in order to provide a more thorough explanation of examples of the invention. However, it will be apparent to those skilled in the art that other examples may be implemented without these specific details.Features of the different examples described may be combined with each other unless features of a corresponding combination are mutually exclusive or such a combination is expressly excluded.

[0042] Fig. 1 shows an embodiment of a carrier cassette having a first side plate 52 and a second side plate 54 that oppose each other in a first direction. The first side plate 52 has a locking groove 56 on an upper side thereof, and the side plate 54 has a locking groove 58 on an upper side thereof. Between the side plates 52 and 54, a lower support rod 60 is provided that extends in the first direction. The lower support rod 60 is fixedly attached to the first side plate 52 and the second side plate 54. Furthermore, two lateral support rods 62 and 64 are provided between the first side plate 52 and the second side plate 54. The two lateral support rods 62 and 64 can oppose each other in a second direction that is perpendicular to the first direction.The lateral support rods 62 and 64 are fixedly attached to the first side plate 52 and the second side plate 54 and thus, together with the side plates 52 and 54 and the lower support rod 60, define a rigid carrier cassette. The carrier cassette further includes an upper locking rod 70 that can be locked in the locking grooves 56 and 58 of the opposing side plates 52 and 54 to hold wafers W1, W2 down in the carrier cassette. Although only two wafers are shown in Fig. 1, it goes without saying that a plurality of wafers, for example, more than 50 or more than 100 wafers, can be arranged side by side in the first direction, or the carrier cassette is designed to accommodate such a plurality of wafers.

[0043] The side plates 52, 54, the lower support bar 60, the lateral support bars 62, 64, and the upper locking bar 70 define two receiving areas for two rows of wafers extending in the first direction, wherein the two receiving areas are arranged side by side in the second direction, which is perpendicular to the first direction. For the sake of clarity, only one wafer of each of the two rows of wafers is shown in Fig. 1: wafer W1 of the first row of wafers and wafer W2 of the second row of wafers. The upper locking bar 70 is designed to hold down the two rows of wafers. For this purpose, the locking bar 70 can be arranged centrally in the second direction. The locking bar has dimensions in the second direction such that it comes into contact with both rows of wafers simultaneously when locked in the locking grooves 56, 58.The locking bar 70 has projections 72 which are designed to separate adjacent wafers of both rows from each other in the first direction when the upper locking bar 70 is locked in the locking grooves 56 and 58.

[0044] Since the extension of the carrier cassette in the direction between the two side plates 52 and 54 is generally greater than in the second direction perpendicular thereto, the first direction will be referred to below as the longitudinal direction for the sake of simplicity, while the second direction will be referred to below as the transverse direction for the sake of simplicity. The direction perpendicular to the longitudinal direction and the transverse direction between the lower holding rod 60 and the locking rod 70 will be referred to below as the vertical direction for the sake of simplicity. The vertical direction can correspond to the direction in which the carrier cassette is immersed in a wafer bath and removed from the wafer bath.

[0045] The first receiving area is delimited in the transverse direction on the outer side by the lateral holding rod 62, on the upper side by the locking rod 70, and on the lower side by the lower holding rod 60. The second receiving area is delimited on the outer side by the lateral holding rod 64, on the upper side by the locking rod 70, and on the lower side by the lower holding rod 60. In the longitudinal direction, the two receiving areas are delimited by the respective side plates 52 and 54, respectively. The holding rod 70 can be configured to delimit the receiving areas on the side facing each other, for example, by parts of the holding rod 70 projecting between wafers spaced apart in the transverse direction. As explained below, additional means can be provided to delimit the receiving areas on the inner side, i.e., to separate wafers adjacent in the transverse direction from one another.Such limiting means may, in examples, be formed by a continuous or interrupted web on the lower support rod, or by one or more central support rods provided between the receiving areas and firmly connected to the side plates.

[0046] The projections 72 are provided to protrude into the receiving areas in order to separate longitudinally adjacent wafers in both rows from one another. The locking bar 70 can be configured to be locked by rotation in the locking grooves 60 and 58, wherein in the locked state the projections 72 protrude into the receiving areas for the above-mentioned purpose. For this purpose, the locking bar and the locking grooves can be designed as described, for example, in the above-mentioned documents DE 20 2015 104 876 U1 or DE 10 2015 224 980 B4. However, it does not require a separate explanation that the locking bars and the locking grooves can be designed in any suitable manner to enable locking of the locking bar in the locking grooves. For example, the locking bar can have an oval or eccentric shape in cross-section in order to be locked by rotation in a locking groove.

[0047] To hold down both rows of wafers, the locking bar 70 is positioned centrally in the transverse direction above the two receiving areas and thus above the two wafers received in the receiving areas. In the locked state, the dimension of the locking bar in the transverse direction is larger than the distance between the wafers W1, W2, at least in the areas where the wafers are to be held down, so that both wafers can be held down.

[0048] Although only one lower support rod 60 is shown in Fig. 1, two or more lower support rods may be provided in other embodiments. Although only one support rod 62 or 64 is provided on each side in the transverse direction in Fig. 1, more than one side rod, for example, two side rods, may be provided in other embodiments.

[0049] Although not shown in Fig. 1, the holding rods 60, 62, 64 can also have respective projections to separate longitudinally adjacent wafers in the two rows from one another. The projections can be designed as disclosed in the above-mentioned documents DE 20 2015 104 876 U1 and DE 10 2015 224 980 B4. For example, the holding rods can be formed by toothed racks with teeth and intermediate spaces, so that a tooth is arranged between each wafer adjacent in the longitudinal direction. The projections in the hold-down rod can also be formed by corresponding teeth to achieve the described functionality.

[0050] Embodiments of different arrangements of lateral and lower holding rods are explained in more detail below with reference to Figs. 2 to 5. Figs. 2 to 5 represent schematic cross-sectional views (section in the transverse and vertical directions). In the examples shown, the upper locking rod 70 has a first row of projections 72a and a second row of projections 72b. The first row of projections 72a protrudes into the first receiving area in which the row of wafers, to which the wafer W1 belongs, is arranged, and the second row of projections 72b protrudes into the second receiving area in which the second row of wafers, to which the wafer W2 belongs, is arranged. Receiving means 12 for mechanical handling of the carrier cassette are provided on the upper side of the side plates, for example in the form of hooks, as shown schematically.

[0051] In the embodiments shown in Fig. 2, two lateral support rods 62a, 62b and 64a, 64b are provided on each side in the transverse direction, each arranged one above the other. Furthermore, in the embodiment shown, two lower support rods 60a and 60b are provided. The lower support rod 60a defines the first receiving area at the bottom, and the lower support rod 60b defines the second receiving area at the bottom. As further shown in Fig. 2, the respective support rods are provided with projections 80 to separate wafers adjacent in the longitudinal direction from one another.

[0052] The embodiment shown in Fig. 3 differs from the embodiment shown in Fig. 2 in that only one lower holding rod 60 is provided. The lower holding rod 60 is provided centrally below the two receiving areas in the transverse direction, wherein the dimensions of the holding rod 60 in the transverse direction are larger, at least in the sections in which the wafers are to be held, than a distance between the wafers adjacent in the transverse direction, so that both transversely adjacent rows can be held jointly by the lower holding rod 60. In the example shown, the lower holding rod 60 has projections 80a and 80b, wherein the projections 80a extend into the first receiving area and the projections 80b into the second receiving area. Like the projections 72a and 72b, the projections 80a and 80b extend at different angles from the lower holding rod 60 and the upper locking bar 70, respectively.Thus, longitudinally adjacent wafers in both rows can be separated from each other by the projections 80a, 80b.

[0053] Fig. 4 shows an embodiment that differs from the embodiment shown in Fig. 3 in that only one lateral holding rod 62 or 64 is provided, and that a central holding rod 90 is provided in the transverse direction between the two receiving areas. The central holding rod 90 is provided with projections 92a and 92b. The projections 92a protrude into the first receiving area, and the projections 92b protrude into the second receiving area. The projections 92a and 92b are thus designed to separate wafers in both rows that are adjacent in the longitudinal direction from one another. The projections 92a and 92b are optional. The central holding rod 90 represents a means for delimiting the two receiving areas in the transverse direction on the side on which they face each other. This makes it more reliable to ensure that wafers that are adjacent in the transverse direction do not come into contact with one another.

[0054] The embodiment shown in Fig. 5 differs from the embodiment shown in Fig. 4 in the design of the lower support rod 60 and in particular in the formation of the projections 80a and 80b. In the example shown, the projections have a section extending in the transverse direction and a section extending in the vertical direction, with at least the section extending in the vertical direction protruding into the first and second receiving areas. In such embodiments, the section of the projections extending in the transverse direction could also be continuous in order to provide a support for the wafers and thereby hold them from below. As shown in Figs.2 to 5, in the embodiments in which a central support rod is provided, the diameter of the lateral and central support rods can be smaller than in the embodiments in which no central support rod is provided, so that the external dimensions of the carrier cassettes are the same.

[0055] Referring to Figs. 6a to 6c, embodiments are described as to how the upper locking bar can be implemented.

[0056] In the example shown in Fig. 6a, the upper locking bar has two rows of projections 72a and 72b, as described above. The projections 72a and 72b extend in different directions from the locking bar 70 and each protrude into the space between two longitudinally adjacent wafers to separate them. The projections 72a and 72b can be formed by respective teeth. For example, an angle of 90° can be formed between the projections 72a and 72b, with one projection extending at an angle of 45° with respect to the height direction and one projection extending at an angle of -45° with respect to the height direction.

[0057] According to Fig. 6b, the locking bar 70 has a series of projections 72c, each of which is configured to separate adjacent wafers of both rows from each other in the first direction. For this purpose, each of the individual projections 72c is configured to protrude into the space between longitudinally adjacent wafers of both rows, so that the wafers of both rows can be separated from each other. In other words, each projection has a dimension in the transverse direction that is greater than the distance between transversely adjacent wafers.

[0058] According to Fig. 6c, the locking bar 70 has four rows of projections 72d, each of which is spaced at 90 eextend in different directions from the locking bar 70. This exemplary embodiment allows increased flexibility with regard to the orientation of the locking bar 70 relative to the receiving areas and thus the wafers. If the respective projections are sufficiently wide, it can be ensured that the wafers adjacent in the longitudinal direction are separated from one another, regardless of the orientation of the locking bar 70 relative to the receiving areas. For illustration, Figs. 7a to 7c show a schematic perspective view of the example shown in Fig. 3, although the lateral holding rods have been omitted for the sake of clarity. As can be seen in Fig. 7a, the projections 72a and 72b are designed as teeth that extend in different directions from the locking bar 70. Fig.Fig. 7b shows a schematic top view, wherein for the sake of simplicity, only two wafers W1 of the first row of wafers and two wafers W2 of the second row of wafers are shown. A respective tooth 72a is arranged between two wafers W1 of the first row, and a respective tooth 72b is arranged between two wafers W2 of the second row. Fig. 7c shows a perspective view of a support rod or locking bar, which may be the support rod 60 or the locking bar 70 or at least a portion of the locking bar 70. As shown, the respective projections extend in two different directions from the rod so that they protrude into the respective receiving areas and thus between the longitudinally adjacent wafers. It should be noted that in embodiments, the locking bar and the lower support rod 60 may have a substantially identical structure with regard to the projections.

[0059] In some embodiments, the protrusions of the support rods may have a shark-tooth design, while the protrusions of the locking rod may have a fishbone design. If the lower support rod also serves to hold more than one row of wafers, it may also have a fishbone design.

[0060] A further embodiment is described with reference to Figs. 8a and 8b. The example shown in Figs. 8a and 8b differs from the example described with reference to Figs. 7a to 7c in the design of the lower holding rod 60. In the example shown in Figs. 8a and 8b, the lower holding rod 60 has a continuous web 94 which is designed to separate the transversely adjacent wafers W1 and W2 from one another. For this purpose, the web 94 protrudes into a space between the transversely adjacent wafers W1 and W2. In other words, the web protrudes from the lower holding rod 60 in the direction of the locking rod 70. As a result, the web 94 delimits the two receiving areas inwards, i.e., between the two rows of wafers. In embodiments, the web can also have interruptions, as long as it is provided in the areas which wafers lie opposite one another in the transverse direction.The web 94 thus represents a means for separating wafers adjacent in the transverse direction. Fig. 9 shows a schematic perspective view of an embodiment which differs from the embodiment shown in Fig. 7a in that the carrier cassette is designed to accommodate three horizontally adjacent rows of wafers. As shown in Fig. 9, the first side plate 52 has a further locking groove 56a on its upper side, and the second side plate 54 has a further locking groove 58a on its upper side. Furthermore, a further upper locking bar 70a is provided, which can be locked in the locking grooves 56a and 58a. The further locking bar 70a is designed to hold down the row of wafers W2 and a further row of wafers W3.Furthermore, the further locking bar 70a in turn has projections which are designed to separate wafers of the two rows of wafers W2 and W3 from one another in the longitudinal direction when the upper locking bar 70a is locked in the locking grooves 56a and 58a. Furthermore, a further lower holding bar 60a is provided, which is firmly attached between the first side plate 52 and the second side plate 54. The structure of the second holding bar 60a can correspond to the structure of the first holding bar 60 with corresponding projections 80a and 80b. Likewise, the structure of the further locking bar 70a can correspond to the structure of the first locking bar 70, with corresponding projections 72a and 72b. In the embodiment shown in Fig.In the example shown in Figure 9, in which the lateral support rods are again omitted for clarity, the carrier cassette thus has three receiving areas defined by the two upper locking bars 70, the lower support rods 60 and 60a, the side plates, and the lateral support rods. It goes without saying that more than three corresponding receiving areas may be provided in exemplary embodiments.

[0061] Examples of central support bars for separating transversely adjacent wafers will now be described with reference to Figs. 10a to 10c.

[0062] According to Fig. 10a, a central support rod 90 is provided between the two receiving areas and thus between the two rows of wafers W1 and W2. The central support rod 90 extends from the first side plate 52 to the second side plate 54 and is attached to the latter. The central support rod thus represents a means for separating the two rows of wafers from one another. In the example shown, the support rod 90 has no projections. In alternative embodiments, the support rod may have corresponding projections 92a and 92b, as described above with reference to Figs. 4 and 5. The example shown in Fig. 10b differs from the example shown in Fig. 10a in that two central support rods 90a and 90b are provided one above the other in the height direction. Such an arrangement can be advantageous to more reliably prevent transversely spaced wafers from coming into contact with one another.

[0063] The example shown in Fig. 10c differs from the example shown in Fig. 10b in that the two stacked central support rods 90a and 90b have respective projections 92a and 92b, as explained above with reference to Figs. 4 and 5. This makes it possible to more reliably ensure in embodiments that longitudinally adjacent wafers do not come into contact with each other.

[0064] In embodiments, separating means are thus provided in order to separate wafers adjacent to one another in the transverse direction, wherein such separating means can be provided, for example, in the form of a web of the lower holding rod or in the form of one or more central holding rods.

[0065] Fig. 11 shows a schematic cross-sectional view to explain how a carrier cassette could be expanded. A solid line 100 schematically shows a side wall for a carrier cassette for two rows of wafers W1 and W2, a dashed line 102 schematically shows a side wall for a carrier cassette for four rows of wafers W1 to W4, and a dash-dotted line 104 schematically shows a side wall for a carrier cassette for six rows of wafers W1 to W6. In principle, carrier cassettes can be expanded as desired. Although different designs of the central holding rods are shown in Fig. 11, it goes without saying that this does not represent any restriction; identical or no central holding rods could be used, and central holding rods could also be provided between the wafers W2 and W3 and / or W4 and W5.

[0066] Although specific embodiments have been described above, it goes without saying that the features of the embodiments can be combined with one another unless explicitly stated otherwise. Thus, the carrier cassette shown in Fig. 1 could be implemented with all the features described with reference to Figs. 2 to 10c. For example, the lower support rod 60, as shown in Fig. 5, could also replace the support rod shown in Fig. 3.

[0067] The present invention thus provides a carrier cassette, which can also be referred to as a substrate carrier, which with its components delimits at least two receiving areas that are arranged next to one another, wherein the locking bar is designed such that it delimits two receiving areas in the carrier cassette at the top, i.e. that it can hold down two rows of wafers. For this purpose, embodiments of the invention provide an apparatus for processing semiconductor wafers, comprising two side plates, on each side at least one bar for laterally holding the substrates, on the upper side a removable bar, and optionally further bars that segment the carrier cassette so that at least two areas for receiving substrates are created, wherein the pressure bar is designed such that it delimits at least two receiving areas.Limitation can also be achieved by a central bar firmly connected to the side plates. A corresponding device can also be designed for transporting and storing semiconductor wafers. Examples include reducing sticking effects, reducing carrier marks, increasing throughput, increasing customer satisfaction, and increasing competitiveness.

[0068] Embodiments of the invention are particularly suitable for handling halved or multiply cut silicon wafers, as they allow two cut halves to be processed side by side in a carrier cassette in a batch process. Treating cut wafers can be advantageous because it can reduce the occurrence of bending, allowing the use of thinner wafers and thus increasing throughput.

[0069] Examples of the invention also relate to a method for using a corresponding carrier cassette, in which two rows of wafers are placed next to one another in the carrier cassette, whereupon the cassette with the wafers is immersed in a bath containing a treatment liquid in order to subject the wafers to a treatment, for example etching or cleaning. Examples of the present invention thus also relate to a method for treating wafers in a batch operation, in which several rows of wafers are placed next to one another in a corresponding carrier cassette and the carrier cassette is then immersed in a liquid bath for the corresponding treatment. Although features of the invention have been described in each case with reference to device features or method features, it is obvious to those skilled in the art that corresponding features can also be part of a method or device.Thus, the device can be configured to carry out corresponding method steps, and the respective functionality of the device can represent corresponding method steps.

[0070] In the foregoing Detailed Description, various features have been grouped together in examples in order to streamline the disclosure. This manner of disclosure should not be interpreted as intending that the claimed examples include more features than are expressly recited in each claim. Rather, as the following claims reflect, the subject matter may lie in fewer than all of the features of a single disclosed example. Accordingly, the following claims are hereby incorporated into the Detailed Description, with each claim being capable of standing as its own separate example.While each claim may stand as its own separate example, it should be noted that although dependent claims in the claims refer to a specific combination with one or more other claims, other examples also include a combination of dependent claims with the subject matter of any other dependent claim or a combination of any feature with other dependent or independent claims. Such combinations are intended to be encompassed unless it is stated that a specific combination is not intended. Furthermore, it is intended to encompass a combination of features of a claim with any other independent claim, even if that claim is not directly dependent on the independent claim.

[0071] The examples described above are merely illustrative of the principles of the present invention. It is understood that modifications and variations of the arrangements and details described will be apparent to those skilled in the art. Therefore, it is intended that the invention be limited only by the appended claims and not by the specific details set forth for the purpose of describing and explaining the examples.

Claims

Claims 1 . A carrier cassette for wafers (W1 - W5) comprising: two side plates (52, 54) opposite one another in a first direction, each of which has a locking groove (56, 56a, 58, 58a) on an upper side thereof; at least one lower support rod (60, 60a, 60b) mounted between the two opposing side plates (52, 54), and at least two lateral support rods (62, 64) mounted between the two opposing side plates (52, 54), an upper locking rod (70, 70a) lockable in the locking grooves (56, 56a, 58, 58a) of the opposing side plates (52, 54) to hold down wafers (W1 - W5) in the carrier cassette, wherein the side plates (52, 54), the at least one lower support rod (60, 60a, 60b), the at least two lateral support rods (62, 64), and the upper locking rod (70, 70a) define two receiving areas for two rows of wafers (W1 - W5) extending in the first direction,wherein the two receiving areas are arranged side by side in a second direction perpendicular to the first direction, and the upper locking bar (70, 70a) is designed to hold down the two rows of wafers (W1 - W5) and has projections (72, 72a - 72d) designed to separate adjacent wafers (W1 - W5) of both rows from each other in the first direction when the upper locking bar (70, 70a) is locked in the locking grooves (56, 56a, 58, 58a).

2. Carrier cassette according to claim 1, wherein the projections (72, 72a - 72d) have a first row of projections (72a, 72d) which are designed to separate wafers (W1 - W5) of one of the two rows which are adjacent in the first direction, and a second row of projections (72b, 72d) which are designed to separate wafers (W1 - W5) of the other of the two rows which are adjacent in the first direction.

3. A carrier cassette according to claim 2, wherein the projections (72a, 72d) of the first row of projections (72a, 72d) extend at a first angle from the upper locking bar (70, 70a), and the projections (72b, 72d) of the second row of projections (72b, 72d) extend at a second angle from the upper locking bar (70, 70a).

4. Carrier cassette according to claim 1, wherein the projections (72, 72a - 72d) comprise a series of projections (72c), each of which is designed to separate adjacent wafers (W1 - W5) of both rows from one another in the first direction.

5. A carrier cassette according to any one of claims 1 to 4, further comprising means for separating the two receiving areas from each other in the second direction.

6. A carrier cassette according to claim 5, wherein the means for separating comprises a central support rod (90, 90a, 90b) mounted between the side plates (52, 54) and separating the two receiving areas from each other in the second direction.

7. Carrier cassette according to claim 6, wherein the central support rod (90, 90a, 90b) has projections (92a, 92b) for separating adjacent wafers (W1 - W5) of the two rows from each other in the first direction.

8. Carrier cassette according to claim 6 or 7, wherein the means for separating comprise a continuous or interrupted web (94) of the at least one lower support rod (60, 60a, 60b), which is designed to separate adjacent wafers (W1 - W5) from one another in the second direction.

9. Carrier cassette according to one of claims 1 to 8, wherein the at least one lower holding rod (60) is designed to delimit both receiving areas downwards.

10. A carrier cassette according to any one of claims 1 to 7, comprising two lower support rods (60a, 60b) mounted between the two opposite side plates (52, 54), each of which delimits one of the two receiving areas downwards.

11. Carrier cassette according to one of claims 1 to 10, wherein the at least two lateral support rods (62, 64) and / or the at least one lower support rod (60, 60a, 60b) have projections (80, 80a, 80b) which are designed to separate adjacent wafers (W1 - W5) from one another in the first direction.

12. Carrier cassette according to claim 9, wherein the at least one lower support rod (60, 60a, 60b) has projections (80a, 80b) which are designed to separate adjacent wafers (W1 - W5) of both rows from one another in the first direction.

13. Carrier cassette according to one of claims 1 to 12, wherein a dimension of the two receiving areas in one direction between the at least one lower holding rod (60, 60a, 60b) and the locking rod (70, 70a) is twice as large as a dimension of the two receiving areas in the second direction.

14. Carrier cassette according to one of claims 1 to 13, which has a plurality of upper locking bars (70, 70a), wherein the side plates (52, 54) each have a plurality of locking grooves (56, 56a, 58, 58a), wherein the side plates (52, 54), the at least one lower holding bar (60, 60a, 60b), the at least two lateral holding bars (62, 64) and the plurality of upper locking bars (70, 70a) delimit more than two receiving areas for more than two rows of wafers (W1 - W5) extending in the first direction, wherein the more than two receiving areas are arranged next to one another in the second direction, and wherein each of the upper locking bars (70, 70a) is designed to hold down two rows of wafers adjacent in the second direction, and has projections (72a, 72b) which are designed to to separate adjacent wafers (W1 - W5) of the two rows from each other in the first direction when the upper locking bar (70, 70a) is in two respective ones of the locking grooves (56, 56a,58, 58a) is locked., 15. Carrier cassette according to one of claims 1 to 14, wherein the respective projections (72, 72a - 72d, 80, 80a, 80b, 92a, 92b) are designed to position rows of wafers (W1 - W5) of a thickness < 160 pm, preferably < 100 pm, with a distance < 7 mm, preferably < 5 mm, between wafers (W1 - W5) in the first direction in the receiving areas.

16. Carrier cassette according to one of claims 1 to 15, wherein the side plates (52, 54) have receiving means (12) on the upper side for mechanical handling of the carrier cassette.

17. A method for using a carrier cassette according to one of claims 1 to 16, wherein two rows of wafers (W1 - W5) are placed next to each other in the carrier cassette.

18. A method for treating wafers (W1 - W5) with a treatment liquid using a carrier cassette according to one of claims 1 to 16, comprising the following steps: Placing two rows of wafers (W1 - W5) next to each other in the carrier cassette; Locking the upper locking bar (70, 70a) in the locking grooves (56, 56a, 58, 58a) in order to hold down the two rows of wafers (W1 - W5) with the locking bar (70, 70a); Placing the carrier cassette with the wafers (W1 - W5) into a bath containing the treatment liquid in order to subject the wafers (W1 - W5) to treatment with the treatment liquid.

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