Wafer boat system, holder rings, and use thereof

Abstract

To provide a wafer boat system, holder rings, and the use thereof.SOLUTION: A wafer boat system comprises a carrier and a plurality of holder rings configured to support a wafer in the carrier. Each of the holder rings has an annular body, and ring projections projecting from the annular body for contact with the wafer. At the ring projections, a local surface area of the annular body is small compared to a circumferential average or median of the local surface area of the annular body, in particular to at least partly compensate for a surface area of the respective ring projection, thereby promoting evenness of vapor deposition on wafers supported on the holder rings in the carrier. The reduced local surface area is preferably realized by a relatively large inner radius of the annular body at the ring projection. The carrier may provide a reference structure for automated wafer positioning.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wafer boat system, a holder ring for such a wafer boat system, and the use of the holder ring and / or the wafer boat system. [Background technology]

[0002] Wafer boats are known for use in batch processing of semiconductor wafers, e.g., deposition onto the wafers. Wafer boats are typically primarily cylindrical structures capable of receiving multiple circular wafers spaced axially apart. The cylindrical axis of the wafer boat may be vertically oriented such that the wafers extend primarily horizontally.

[0003] US Patent No. 6,287,112 describes the general problem of potential non-uniformity across the wafer surface when process gas is delivered radially. In particular, so-called edge effects can occur, resulting in, for example, increased material deposition at the edge of the wafer compared to the center of the wafer. US Patent No. 6,287,112 also discusses the possibility of using rings to increase uniformity. In some variations, the wafer may be supported on such a ring, such that the ring may be considered a holder ring.

[0004] While past developments have contributed to improved deposition uniformity across the wafer surface, further improvements remain desirable. Meanwhile, wafer processing is desired to be efficient. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 6,287,112 Summary of the Invention [Means for solving the problem]

[0006] With a view to improving deposition uniformity across the wafer surface while maintaining or improving wafer processing efficiency, one aspect of the present invention provides a wafer boat system.

[0007] The wafer boat system includes a carrier including a first end member located at a first axial end of the carrier, a second end member located at a second axial end of the carrier, and at least three spaced-apart axial rods, each connecting the first end member with the second end member, each including a series of radially inwardly extending rod projections defining axially spaced holder ring positions.

[0008] The wafer boat system includes a plurality of holder rings, each of which is engageable with a rod projection, and is configured to position the holder rings within the carrier at one of the holder ring positions such that when the holder rings are engaged, the holder rings support the wafers within the carrier when at least the axial rods are oriented vertically.

[0009] Each of the holder rings has an annular body and a ring protrusion protruding from the annular body, the ring protrusion being arranged to contact the wafer and space the wafer from the annular body when the wafer is supported by the holder ring in the carrier.

[0010] Such a ring protrusion is generally advantageous, among other things, because it eliminates the need for the wafer to directly contact the carrier, which can contribute to non-uniformity, while by spacing the wafer away from the annulus, the ring protrusion allows an end effector of a wafer positioning robot to reach beneath the supported wafer without interference from the annulus.

[0011] However, it has been found that such ring protrusions themselves may also contribute somewhat to non-uniformity, and in particular deposition on the wafer may be locally reduced in areas adjacent such ring protrusions. The present invention is based on this insight, and is further based on the insight that such non-uniformity associated with the ring protrusions may be advantageously reduced by designing the annulus to at least partially compensate for the undesirable deposition effects of the ring protrusions themselves, as described in more detail below.

[0012] The toroid preferably has a local surface area that varies along its circumference, and at the ring protrusions the local surface area of ​​the toroid is small compared to the circumferential mean or median local surface area of ​​the toroid, in particular to at least partially compensate for the surface area of ​​each ring protrusion, which may promote uniformity of deposition on wafers supported on a holder ring in a carrier.

[0013] It has been found that such at least partial compensation can advantageously result in a more uniform, i.e., more evenly distributed, deposition on the wafer, particularly near the ring protrusion, while the known advantages of the ring protrusion itself can be maintained or improved upon. In particular, the end effector can still move between the annular body and the wafer due to the ring protrusion spacing the supported wafer away from the annular body.

[0014] It has also been found that the aforementioned compensation can be achieved particularly effectively by a locally increased inner radius, and without wishing to be bound by theory, it is believed that this effect may be associated with the inner radius of the annulus generally being close to the edge of the wafer, and in particular closer than the outer radius of the annulus.

[0015] With that in mind, it is preferred that the annulus has an inner radius that varies along its circumference, and at the ring projection the inner radius is larger compared to the circumferential mean or median of the inner radii of the annulus.

[0016] The large inner radius in the ring protrusion may result in a reduction in local surface area, particularly in a manner that provides a relatively effective compensation for localized deposition effects in the ring protrusion. Thus, in the ring protrusion, the relatively large inner radius may contribute to a relatively small local surface area, as described.

[0017] Nevertheless, in some embodiments, some or all of the compensation, in particular the reduction in the local surface area of ​​the annulus, may be achieved differently by a locally increased inner radius of the annulus, for example by a locally decreased outer radius of the annulus, and / or by one or more openings in the annulus between the inner and outer radii.

[0018] The local surface area may be defined based on a circumferential window of 30 degrees or less, preferably 20 degrees or less, more preferably 10 degrees or less, for example about 5 degrees, about 2 degrees, or about 1 degree. In this way, a value of the local surface area may be determined for essentially any circumferential position, including the circumferential position of the ring projection. It should be understood that determining such a value typically involves measuring and then adding the surface areas of all the surfaces of the section of the annulus that is within the circumferential window. Thus, by determining the values ​​of the local surface area at regular circumferential intervals, an average or median value of the local surface area can be calculated for the entire annulus. The windows of adjacent intervals may or may not overlap each other, so long as there are no gaps between the windows.

[0019] Of course, the inner radius of the annular body may be determined for any circumferential position. However, of course, any local expansion of the inner radius will typically extend along a finite circumferential range or window. Thus, a window-based approach similar to that described above may also be applied to the inner radius. Within such a window, the inner radius may still be variable, for example increasing towards the circumferential position of the ring projection, as described elsewhere herein.

[0020] A further aspect provides a holder ring explicitly configured for use as one of the holder rings of the wafer boat systems described herein, the holder ring having an annular body and a ring protrusion protruding from the annular body, the ring protrusion being arranged to contact a wafer and space the wafer from the annular body when the wafer is supported by the holder ring.

[0021] Such a holder ring can provide advantages corresponding to those described herein for a wafer boat system, and may be used, for example, as a replacement for known holder rings and in combination with known carriers to form a wafer boat system.

[0022] The holder ring and / or wafer boat system may advantageously be used to process wafers, during which the wafers contact the ring protrusions of the holder ring that support the respective wafers, and preferably the wafers do not directly contact the carrier. The processing may involve vapor deposition. In certain applications, silicone-based compounds are used for the vapor deposition.

[0023] Advantageous elaborations of the above-mentioned aspects and options are provided by the features of the dependent claims, as further explained in the following detailed description.

[0024] The present invention will be further described below with reference to examples of embodiments and drawings. The drawings are schematic and merely illustrative. The description of the embodiments herein can also be understood independently of the drawings. In the drawings, corresponding elements are provided with corresponding reference signs. For clarity of the drawings, an element may be indicated by a reference sign only in one or some of the drawings and / or only for one or some of the instances of the element in the drawings. In the drawings: [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 shows a perspective view of a holder ring. [Diagram 2] FIG. 2 shows a perspective view of the carrier. [Diagram 3] FIG. 3 shows a top view of the holder ring of FIG. 1 holding a wafer. [Figure 4] FIG. 4 shows a side view of the holder ring of FIG. 1 holding a wafer. [Diagram 5] FIG. 5 shows detail A of FIG. [Figure 6] FIG. 6 shows detail B of FIG. [Figure 7a] FIG. 7a shows a perspective view of a holder ring according to an embodiment of the present invention. [Figure 7b] FIG. 7b shows a bottom view of the holder ring of FIG. [Figure 8] FIG. 8 shows a cross-sectional side view of a portion of the holder ring of FIG. 1 and a further similar holder ring, with a portion of the carrier of FIG. [Figure 9] FIG. 9 shows a side view of the carrier of FIG. [Figure 10] FIG. 10 shows detail C of FIG. [Figure 11] FIG. 11 shows detail D of FIG. [Figure 12] FIG. 12 shows a perspective view of a possible variant of the holder ring with a part of the carrier. [Figure 13] FIG. 13 shows a perspective view of the ring projection and associated parts of the holder ring of FIG. 12 together with a portion of a wafer. [Figure 14] FIG. 14 shows a side view of the holder ring with the carrier part of FIG. 12 with a wafer. [Figure 15] FIG. 15 shows a graph depicting simulation results associated with the wafer boat system of FIGS. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] 1-11 show a portion of an embodiment of a wafer boat system 1. FIGs. 12-14 show a portion of an embodiment of a wafer boat system 1. Some geometric features of the ring projection 13 and adjacent sections of the annular body 12 differ between the two embodiments, as further described elsewhere herein, while the two embodiments are otherwise similar. Further variations are possible, as would be apparent to one of ordinary skill in the art having the benefit of this disclosure.

[0027] The wafer boat system 1 comprises a carrier 2 having a first end member 3 located at a first axial end 4 of the carrier 2, a second end member 5 located at a second axial end 6 of the carrier 2, and at least three spaced apart axial rods 7, each connecting the first end member 3 with the second end member 5, and each having a series of radially inwardly extending rod projections 8 defining axially spaced apart holder ring positions 9.

[0028] The wafer boat system 1 includes a plurality of holder rings 10, each engageable with a rod projection 8, and the holder rings 10 are positioned within the carrier 2 at one of the holder ring positions 9. When so engaged, the holder ring 10 is configured to support a wafer 11 within the carrier 2 when at least the axial rods 7 are oriented vertically.

[0029] Each of the holder rings 10 has an annular body 12 and a ring protrusion 13 protruding from said annular body 12. The ring protrusion 13 is arranged to contact the wafer 11 and space the wafer 11, particularly axially, from the annular body 12 when the wafer 11 is supported by the holder ring 10 in the carrier 2. By way of example, the resulting axial distance between the annular body 12 and the wafer 11 may be about 4.5 mm.

[0030] By way of example, Figures 3-4 and Figures 13-14 show how a wafer 11 can be supported by a holder ring 10, in which figures the outline of the wafer 11 is shown in dashed lines. In Figure 14 it can be seen how the holder ring 10 can be supported therebetween by rod projections 8 of the axial rods 7 of the carrier 2. The arrangement of Figure 14 may be repeated along the axial direction of the carrier 2, so that the carrier 2 comprises an axial series of holder rings 10 with a wafer 11 on each holder ring 10, the wafers 11 being axially spaced apart from the annular bodies 12 of the holder rings 10.

[0031] In an embodiment, the toroidal body 12 is an annular disc-like body 12, i.e., the toroidal body 12 is formed as a substantially annular disc.

[0032] Thereby, the ring 12 may be relatively flat and thin in the axial direction, e.g., plate-like, while helping to reduce edge effects during processing of the wafers 11. The relatively thin ring 12 advantageously allows a relatively large number of wafers 11 to be supported in the carrier 2 while being spaced apart from the ring 12. The ring 12 may be strong and rigid enough to provide a robust intermediate support structure between the rod projections 8 and the wafers 11. By way of example, the axial thickness of the ring 12 may be about 1.75 mm.

[0033] The annular body 12 preferably has a local surface area that varies along its circumferential direction CD, where at the ring protrusions 13 the local surface area of ​​the annular body 12 is small compared to the circumferential mean or median of the local surface area of ​​the annular body 12, in particular to at least partially compensate for the surface area of ​​each ring protrusion 13. Thereby, uniformity of deposition on the wafer 11 supported on the holder ring 10 in the carrier 2 may be promoted.

[0034] The annular body 12 preferably has an inner radius IR that varies along its circumferential direction CD, and at the ring projection 13 the inner radius IR is larger compared to the circumferential mean or median of the inner radii IR of the annular bodies 12, resulting in a particular reduction in local surface area.

[0035] As an example, in Fig. 3 it can be seen that the inner radius IR has the same value along most of the circumference of the ring 10, but not all of the circumference. In particular, the inner radius IR now increases locally at the circumferential position CP13 of the ring protrusion 13. Furthermore, as explained elsewhere herein, the inner radius IR now decreases locally at the two portions 23. It will be appreciated that the ring protrusion 13 itself may be integrally formed with the annular body 12, but is not considered to be part of the annular body 12. With that in mind, the ring protrusion 13 itself is ignored when measuring the inner radius IR of the annular body 12 at the ring protrusion 13.

[0036] In the ring protrusion 13, the relatively large inner radius IR may contribute to a relatively small local surface area.

[0037] In an embodiment, the local surface area is defined based on a circumferential window CW of 30 degrees or less, preferably 20 degrees or less, more preferably 10 degrees or less. However, the circumferential window CW may be at least 1 degree, for example 2 degrees or 5 degrees. Simply as an illustration of the concept of a circumferential window, one such window CW is shown in FIG. 3 at one arbitrary circumferential position. Of course, such a circumferential window CW may be applied at regular intervals along the circumferential direction CD.

[0038] In an embodiment, in the ring projection 13, the inner radius IR of the annular body 12 is at least 1% greater than the circumferential mean or median of the inner radii IR of the annular bodies 12.

[0039] In this way, a particularly effective, at least partial compensation can be achieved with respect to the ring protrusion. In the embodiment shown in Fig. 3, the inner radius IR of the annular body 12 is enlarged by up to about 7% compared to the main value of the inner radius IR, which in this case corresponds to the circumferential mean or median value of the inner radius IR of the annular body 12.

[0040] In an embodiment, along a circumferential section 14 of the annular body 12 adjacent the ring projection 13 , the inner radius IR of the annular body 12 increases towards a circumferential position CP 13 of the ring projection 13 .

[0041] In this way, advantageously, the increase in the inner radius IR can be relatively localized at the ring projection 13 without excessive localized strength reduction of the annulus 12.

[0042] As an example, in Fig. 6 it can be seen that here the inner radius IR steadily increases towards the ring projection 13 in the section 14 adjacent to the ring projection 13. Although a substantially linear or triangular increase is shown here, different types of increase are possible. For example, in the embodiment of Figs. 12 to 14 the increase is substantially parabolic, the apex of the parabola being disposed at the ring projection 13.

[0043] In an embodiment, the increase in the inner radius IR forms a distinct recess or notch in the circumferential section 14 adjacent to the ring projection 13. The recess or notch may in particular differ, for example by having an edge at the circumferential boundary of the section 14, and the rate of change of the inner radius along the circumferential direction CD may be discontinuous. Thereby, the increase in the inner radius IR may also be relatively well localized to the respective ring projection 13. Nevertheless, in some alternative embodiments, the increase in the inner radius IR may form a smooth transition between the section 14 and further sections further away from the ring projection 13.

[0044] In an embodiment, the ring projection 13 extends radially inwardly from the annular body 12 beyond a local inner radius IR of the annular body 12 .

[0045] Such a configuration allows the holder ring 10 to support the wafer 11 at a location radially inward from the inner radius IR of the annular body 12. Advantageously, it also allows the wafer 11 to be supported somewhat inward from its outer edge without the annular body 12 substantially overlapping the wafer 11. It also allows some tolerance to the lateral positioning of the wafer 11 to be provided, if desired.

[0046] In an embodiment, the ring projection 13 is connected to the annular body 12 at and / or adjacent to the inner radius IR of the annular body 12 .

[0047] Thereby, the surface area of ​​the ring protrusion 13 can be kept relatively small, particularly while the annular body 12 extends radially outward beyond the edge of the wafer 11, helping to reduce edge effects and forming a robust support structure.

[0048] In an embodiment, the distal ends 15 of the ring projections 13 are spaced radially inward and / or axially from the annular body 12, and the distal ends 15 are disposed to contact the wafer 11 when the wafer 11 is supported by the holder ring 10. Preferably, the distal ends 15 are spaced both radially inward and axially from the annular body 12.

[0049] The axial spacing of the distal end 15 from the annular body 12 facilitates the wafer 11 being axially spaced from the annular body 12 when supported and for an end effector to reach between the wafer 11 and the annular body 12 for automatic positioning of the wafer 11. The advantages of the radially inward spacing of the distal end 15 from the annular body 12 correspond to those set forth above for the ring protrusion 13 extending radially inward beyond the local inner radius IR of the annular body 12.

[0050] In an embodiment, a proximal section 16 of the ring projection 13 projects axially from the annular body 12, and a distal section 17 of the ring projection 13 extends radially inward from the proximal section 16 of the ring projection 13 a distance from the annular body 12. Examples of such configurations can be seen in Figures 12-14.

[0051] In an embodiment, a proximal section 16 of the ring projection 13 projects radially inward from the annular body 12, and a distal section 17 of the ring projection 13 extends axially from the proximal section 16 of the ring projection 13 a distance from the annular body 12. Examples of such configurations can be seen in Figures 1, 3, 4, 6, and 7a and 7b.

[0052] With the latter geometric configuration of the ring projections 13, the holder ring 10 may in some cases be more economically manufactured, although it has been found that the previous variants may also be technically and economically viable. Further variants are possible, for example variants in which the ring projections 13, or at least parts thereof, extend at an oblique angle, as an alternative to the relatively straight proximal and distal ends specifically shown.

[0053] In an embodiment, when the holder ring 10 engages with the rod projections 8 of the axial rods 7 of the carrier 2, each ring projection 13 is circumferentially spaced from the axial rods 7. This is particularly true when the holder ring 10 is fully received within the carrier 2, so that each of the axial rods 7 engages with the holder ring 10, particularly at a respective circumferential position CW7 that may be predefined, for example, by variation of the outer radius OR of the annular body 12, as described elsewhere herein.

[0054] Thereby, advantageously, accumulation of localized processing effects of the axial rods 7 and the ring protrusions 13 can be prevented. See, for example, FIG. 12, where it can be seen that all three axial rods 7 are circumferentially spaced apart from all three ring protrusions 13. However, as should be understood, both the axial rods 7 and the ring protrusions 13 are preferably distributed substantially along the circumferential direction CD, while the axial rods 7 are arranged such that the holder ring 10 and the wafer 11 are laterally removable from the carrier 2.

[0055] In an embodiment, the annular body 12 has an outer radius OR that varies along its circumferential direction CD, and the variation in the outer radius OR determines the rod positions CP7 of each of the axial rods 7 along the circumferential direction CD of the annular body 12.

[0056] In this way, a robust and reliable engagement between the annular body 12 and the axial rods 7, in particular a reliable circumferential positioning of the ring projections 13 with respect to the axial rods 7, can be provided. The rod position CP7 is shown in figures 1 and 3, while figure 12 shows a portion of the axial rods 7 in a position corresponding to a deformation of the holder ring 10. In order to further promote a robust and reliable engagement between the annular body 12 and the axial rods 7, in particular its rod projections 8, at the rod position CP7, a respective recess 22 may be provided in the bottom surface of the annular body 12, as shown for example in figures 7a and 7b and 8.

[0057] In an embodiment, the variation of the outer radius OR further provides a passage 18 for at least a portion of the axial rod 7 when the annular body 12 moves within the carrier 2 to allow the axial rod 7 to be in a determined position.

[0058] Thereby, the axial rods 7 can be relatively well distributed in the circumferential direction CD for robust support of the holder ring 10, while the holder ring 10 can still be moved detachably on the carrier 2, in particular between the axial rods 7 where the passages 18 are provided.

[0059] In an embodiment, the annular body 12 has an inner radius IR that varies along its circumferential direction CD, and in at least some passages 18 of the axial rods 7, the inner radius IR is smaller compared to the circumferential mean or median of the inner radii IR of the annular body 12.

[0060] In this way, possible accumulation effects of the passages 18 can be at least partially compensated. It has been found that such a reduction in the inner radius IR can be relatively small, for example as seen in FIG. 5, while still being effective. The reduction in the inner radius preferably does not overlap circumferentially with the axial rods 7 when positioned at their end position CP7, in order to prevent accumulation of effects due to the axial rods 7 and the reduced inner radius. On the other hand, the reduction in the inner radius IR preferably extends along the circumferential section 23 corresponding to the respective passage 18, as seen in FIG. 5. Of course, at least in this respect, the passages 18 extend up to, but do not include, the space occupied by the axial rods 7 when positioned at their end position CP7.

[0061] In an embodiment, referring to FIG. 7a, the annular body 12 has an inner radius IR that varies along its circumferential direction CD, and at a circumferential position CP18 that at least partially overlaps with an end position CP7 for at least a portion of the axial rod 7, the inner radius IR is larger compared to the circumferential mean or median of the inner radii IR of the annular body 12.

[0062] In this way, possible deposition effects due to the axial rods 7 can be at least partially compensated for. The increase in inner radius IR preferably circumferentially overlaps with the axial rods 7 when positioned at its end position CP7.

[0063] 9-11, adjacent at least one of the first end member 3 and the second end member 5, the first end 19 and / or second end 20 of each of the axial rods 7 extends radially inwardly into the carrier 2 beyond the rod projection 8 and is dimensioned to provide a reference structure 21 for a robot for use in automated positioning of the wafer 11 in the carrier 2 by an end effector. In an embodiment, the reference structure 21 defines a lateral component of a target wafer position within the carrier 2. In an embodiment, the reference structure 21 is dimensioned to receive a wafer 11 without any holder ring therein.

[0064] Such a reference structure 21 may advantageously enable a wafer positioning robot with an end effector to learn the appropriate lateral position of the wafer in the carrier 2, in particular by repeatedly fully engaging a wafer or dummy wafer with the reference structure 21 while sensing or otherwise determining the full engagement of the end effector and registering the corresponding position of the end effector. Thereafter, when positioning a wafer in the carrier 2, the learned lateral wafer position may be applied to accurately position the wafer 11 on the holder ring 10 in a substantially feed-forward manner, at least without the need for sensing the lateral position of the wafer in the carrier 2 for each wafer. In this sense, the reference structure 21 may be considered as a calibration structure and / or the related procedure described above may be considered as a calibration procedure for such a wafer positioning robot.

[0065] The holder ring 10 and / or wafer boat system 1 described herein may be used to process wafers 11 during which the wafers 11 contact the ring protrusions 13 of the holder ring 10 that support the respective wafers 11, but preferably do not directly contact the carrier 2. In an embodiment, the processing involves deposition, particularly using a silicone-based compound such as Si3H8.

[0066] FIG. 15 shows a graph representing the results of a simulation based on a computer model of the wafer boat system 1 shown in FIGS. 1-11, i.e. using the holder ring 10 shown in FIGS. 1 and 3-8. In the graph of FIG. 15, the horizontal axis represents the circumferential position CP in degrees, where a value of zero degrees corresponds to the position CP7 seen at the top of FIG. 3, and the values ​​increase counterclockwise in the diagram of FIG. 3. The position CP7 of the rod 7 and the position CP13 of the ring protrusion 13 are shown as vertical dashed lines in FIG. 15. Meanwhile, the vertical axis represents the growth rate GR in terms of a factor of 100 pm (i.e. 1 Angstrom) per minute. Thus, the data points shown in the graph FIG. 15 represent the growth rate at a particular circumferential position.

[0067] The growth rate data shown in FIG. 15 was simulated for the indicated circumferential positions at a radial position 2 mm inward from the upper outer edge of the supported wafer based on a simulation of deposition using Si3H8 as the silicone-based compound. The resulting growth rate values ​​are in the range of 19.76-20.09, i.e. in the range of 0.33, while the circumferential average of the growth rate GR is 20.0. On this basis, it can be said that the remaining non-uniformity at the edge of the wafer is as low as (0.33 / 20.0=) 1.65%. In contrast, for the known wafer boat system, the value of the same non-uniformity metric was found to be as high as 7.5% in the corresponding simulation, indicating that the design according to the invention can provide a substantial improvement in uniformity. In particular, it can be seen in FIG. 15 that the range of growth rate values ​​around the circumferential position CP13 of the ring protrusion is very small, thanks to the effect that the ring protrusion 13 is at least partially compensated for by the locally reduced surface area and / or inner radius IR of the annular body 12.

[0068] The present invention has been described herein using examples of embodiments and drawings, which do not limit the scope of the present invention as defined by the claims. Within the above scope, many variations, combinations and extensions are possible, as will be understood by those skilled in the art who have the benefit of this disclosure. For example, the number of axial rods of the carrier and / or the number of ring protrusions of the holder ring may be greater than 3. All such variations are within the scope of the present invention as defined by the claims. [Explanation of symbols]

[0069] List of References 1. Wafer Boat System 2. Career 3. First End Member 4. A first shaft end of the carrier 5. Second End Member 6. The second shaft end of the carrier 7. Axial rod 8. Rod protrusion 9. Holder ring position 10. Holder ring 11. Wafer 12. Circular bodies 13. Ring protrusion 14. Circumferential section adjacent to the ring projection 15. Distal end of ring projection 16. Proximal section of ring projection 17. Distal section of ring projection 18. Passage for axial rod 19. First end section of axial rod 20. Second end section of axial rod 21. Reference structure 22. Recess in annular body of rod projection 23. Circumferential section with reduced inside radius CD. Circumferential direction CP. Circumference position CP7 Circumferential rod position CP13. Circumferential position of ring protrusion CW. Circumferential window GR. Growth rate IR. Inside radius of the ring OR outer radius of the torus

Claims

1. 1. A wafer boat system, comprising: a carrier comprising a first end member located at a first axial end of said carrier, a second end member located at a second axial end of said carrier, and at least three mutually spaced axial rods connecting said first end member with said second end member respectively, each rod comprising a series of radially inwardly extending rod projections defining axially spaced holder ring positions; a plurality of holder rings each engaging with one of said rod projections and positionable within said carrier at one of said holder ring positions, said holder rings being configured, when engaged, to support a wafer within said carrier at least when said axial rod is vertically oriented; each of the holder rings has an annular body and a ring protrusion protruding from the annular body, the ring protrusion being disposed to contact the wafer and space the wafer from the annular body when the wafer is supported by the holder ring in the carrier; A wafer boat system, wherein the annular body has a local surface area that varies along its circumference, and at the ring protrusions, the local surface area of ​​the annular body is small compared to a circumferential average or median of the local surface area of ​​the annular body, in particular to at least partially compensate for the surface area of ​​each of the ring protrusions, thereby promoting uniformity of deposition on wafers supported on the holder ring in the carrier.

2. 2. The wafer boat system of claim 1, wherein the localized surface area is defined based on a circumferential window of 30 degrees or less, preferably 20 degrees or less, more preferably 10 degrees or less.

3. 2. The wafer boat system of claim 1, wherein the annular body has an inner radius that varies along its circumference, and at the ring protrusion, the inner radius is larger compared to a circumferential average or median of the inner radii of the annular body, and in particular, at the ring protrusion, the relatively larger inner radius contributes to the relatively smaller local surface area.

4. 1. A wafer boat system, comprising: a carrier comprising a first end member located at a first axial end of said carrier, a second end member located at a second axial end of said carrier, and at least three mutually spaced axial rods connecting said first end member with said second end member respectively, each rod comprising a series of radially inwardly extending rod projections defining axially spaced holder ring positions; a plurality of holder rings each engaging with one of said rod projections and positionable within said carrier at one of said holder ring positions, said holder rings being configured, when engaged, to support a wafer within said carrier at least when said axial rod is vertically oriented; each of the holder rings has an annular body and a ring protrusion protruding from the annular body, the ring protrusion being disposed to contact the wafer and space the wafer from the annular body when the wafer is supported by the holder ring in the carrier; 11. A wafer boat system, comprising: an annular body having an inner radius that varies along its circumference, and at the ring protrusion, the inner radius is larger compared to a circumferential average or median of the inner radii of the annular body, resulting in a reduction in particular local surface area.

5. 5. The wafer boat system of claim 3 or 4, wherein at the ring projection, the inner radius of the annular body is at least 1% greater than the circumferential mean or median of the inner radii of the annular body.

6. 5. The wafer boat system of claim 3 or 4, wherein along a circumferential section of the annular body adjacent the ring protrusion, the inner radius of the annular body increases toward the circumferential position of the ring protrusion.

7. 5. The wafer boat system of claim 3 or 4, wherein the ring protrusion extends radially inward from the annular body beyond a local inner radius of the annular body.

8. 5. The wafer boat system of claim 1, wherein a distal end of the ring projection is radially inwardly and axially spaced from the annular body, the distal end being disposed to contact the wafer when the wafer is supported by the holder ring.

9. 9. The wafer boat system of claim 8, wherein a proximal section of the ring projection projects axially from the annular body and a distal section of the ring projection extends radially inward from the proximal section of the ring projection a distance from the annular body.

10. 9. The wafer boat system of claim 8, wherein a proximal section of the ring projection projects radially inward from the annular body and a distal section of the ring projection extends axially from the proximal section of the ring projection a distance from the annular body.

11. 5. The wafer boat system of claim 1, wherein when the holder ring engages with the rod projections of the axial rod of the carrier, each of the ring projections is circumferentially spaced from the axial rod.

12. 5. The wafer boat system of claim 1, wherein the annulus has an outer radius that varies along its circumference, the variation in the outer radius determining a rod position of each of the axial rods along the circumference of the annulus.

13. 13. The wafer boat system of claim 12, wherein the annulus has an inner radius that varies along its circumference, and in at least some passages of the axial rods, the inner radius is smaller compared to a circumferential average or median of the inner radii of the annulus.

14. 13. The wafer boat system of claim 12, wherein the annular body has an inner radius that varies along its circumference and at least partially overlaps end locations of at least some of the axial rods at circumferential locations, and the inner radius is larger than a circumferential average or median of the inner radii of the annular body.

15. 1. A wafer boat system, comprising: a carrier comprising a first end member located at a first axial end of said carrier, a second end member located at a second axial end of said carrier, and at least three mutually spaced axial rods connecting said first end member with said second end member respectively, each rod comprising a series of radially inwardly extending rod projections defining axially spaced holder ring positions; a plurality of holder rings each engaging with one of said rod projections and positionable within said carrier at one of said holder ring positions, said holder rings being configured, when engaged, to support a wafer within said carrier at least when said axial rod is vertically oriented; each of the holder rings has an annular body and a ring protrusion protruding from the annular body, the ring protrusion being disposed to contact the wafer and space the wafer from the annular body when the wafer is supported by the holder ring in the carrier; A wafer boat system, wherein adjacent at least one of the first end member and the second end member, a first end and / or a second end of each of the axial rods extends radially inwardly into the carrier beyond the rod projection, thereby dimensioned to provide a reference structure for a robot for use in automatically positioning a wafer in the carrier by an end effector.

16. 16. The wafer boat system of claim 15, wherein the reference structure defines a lateral component of a target wafer position within the carrier.

17. 20. The wafer boat system of claim 16, wherein the reference structure is dimensioned to receive a wafer therein without any holder ring.

18. 18. A holder ring expressly configured for use as one of the holder rings of a wafer boat system according to any one of claims 1-4 and 15-17, wherein the holder ring has an annular body and a ring protrusion protruding from the annular body, the ring protrusion being arranged to contact the wafer and space the wafer from the annular body when the wafer is supported by the holder ring.

19. 18. Use of the wafer boat system according to any one of claims 1 to 4 and 15 to 17 for processing wafers, wherein during the processing, the wafers come into contact with the ring protrusions of the holder ring supporting each of the wafers, and preferably the wafers do not come into direct contact with the carrier.

20. 20. Use according to claim 19, wherein the treatment involves deposition, in particular using silicone-based compounds.

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