Method and device for adjusting a position of a notch on the outer circumference of a wafer made of a semiconductor material
The method and device for adjusting the recess position on semiconductor wafers by enlarging the notch through uneven grinding address the precision issues of conventional methods, enabling accurate alignment and enhancing wafer suitability for semiconductor processes.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SILTRONIC AG
- Filing Date
- 2025-09-30
- Publication Date
- 2026-05-15
AI Technical Summary
Conventional devices for creating a groove in a crystal rod to align semiconductor wafers are not precise enough, leading to inaccuracies in positioning the recess relative to the crystal orientation, making some wafers unsuitable for semiconductor processes.
A method and device that adjust the position of the recess on semiconductor disks by enlarging the notch through uneven grinding, using X-ray imaging to determine the deviation from the desired crystal orientation and aligning the grinding process accordingly.
Achieves precise alignment of the recess relative to the crystal orientation, allowing for improved suitability of wafers for semiconductor processes by adjusting the notch position up to 0.6°.
Smart Images
Figure EP2025078044_15052026_PF_FP_ABST
Abstract
Description
[0001] 202400022 / WH
[0002] Method and apparatus for adjusting the position of a recess on the outer circumference of a disk made of a semiconductor material
[0003] The present invention relates to a method for adjusting the position of a recess, in particular a so-called notch, on the outer circumference of a disk made of a semiconductor material, e.g. a so-called wafer, and to a corresponding device for this purpose.
[0004] State of the art
[0005] Semiconductor wafers, such as silicon wafers, are typically produced from a crystal rod, usually a single crystal of the semiconductor material in question. Such a crystal rod or single crystal can be produced, for example, using the so-called Czochralski process. In this process, the single crystal is extracted from a crucible containing molten semiconductor material using a seed. This method is therefore also known as the crucible drawing process or the crucible drawing process.
[0006] Such a crystal rod, or single crystal, can also be obtained, for example, using the FZ method, also known as the floating-zone method or zone-pulling method. In this process, a polycrystal, i.e., a crystal made of polycrystalline semiconductor material, is melted and then recrystallized. The single crystal is formed during this recrystallization process.
[0007] The crystal rod can then be ground to achieve a more cylindrical shape. However, before the crystal rod is cut into numerous thin slices, known as wafers, a groove is typically cut into one of the outer surfaces of the crystal rod, running along its longitudinal axis. This groove is also known as a notch groove. This groove results in the individual slices or wafers being produced having a notch (or, more generally, a cutout) on their outer circumference.
[0008] This recess serves to align the disk during subsequent semiconductor processes, e.g., when applying circuits to the disk. The 202400022 / WH is intended for this purpose.
[0009] 2
[0010] The recess must be arranged at a position predetermined with respect to a crystal orientation (or specifically a crystallographic orientation) of the disk. Similarly, the groove must also be placed in a position predetermined with respect to the crystal orientation of the crystal rod. Technically significant positions for this recess include, for example, the crystallographic directions
[0100] and
[0110] .
[0011] To ensure the groove in the crystal rod, and thus the subsequent recess in the disk, is in the desired position, the crystal rod is measured appropriately. The crystal rod can then be aligned accordingly to create the groove, for example, by grinding. One method for measuring the crystal rod, as well as the general process of creating the groove, is explained in more detail in DE 100 23 001 A1.
[0012] However, it has now become apparent that conventional devices for creating the groove at the desired position relative to the crystal rod's orientation are often not precise enough. This can be due to various factors, such as the devices themselves or the setting accuracy. Consequently, the recess on the resulting wafer is not positioned with sufficient accuracy relative to the crystal orientation. Such wafers are then sometimes unusable, or at least not suitable for all types of semiconductor processes, as achieving the desired wafer orientation is either impossible or extremely difficult.
[0013] Against this background, the task arises to specify a way in which the position of such recesses in disks made of semiconductor material corresponds more precisely to a desired position with respect to the crystal orientation.
[0014] Disclosure of the invention
[0015] According to the invention, a method and a device for adjusting the position of a recess on the outer circumference of a disk made of a semiconductor material, comprising the features of the independent claims, are proposed. Advantageous embodiments are the subject of the dependent claims and the following description. 202400022 / WH
[0016] 3
[0017] The invention relates to disks made of a semiconductor material, in particular so-called wafers, and to the notch or recess in such disks that serves to align the disks in subsequent uses. To obtain such a disk, a groove can be cut into the outer surface of a crystal rod made of the semiconductor material, running along a longitudinal axis of the crystal rod. The disk can then be obtained by cutting the crystal rod after the groove has been cut, e.g., by sawing. Typically, a multitude of such disks are obtained, each of which then has a notch corresponding to the groove. The cutting of the crystal rod is carried out, in particular, perpendicular to the longitudinal direction of the crystal rod.
[0018] However, if the groove in the crystal rod is not arranged at a position specified with respect to a crystal orientation of the crystal rod, this also applies to the position of the recess of the individual disks that are produced from the crystal rod.
[0019] The position of the notch relative to the crystal orientation of the disk is defined, in particular, by a position line lying in the plane of the disk, which runs midway between two lateral boundaries of the notch. Typically, such a notch has a (lying in the plane of the disk) at least substantially triangular shape, with its apex, or possibly rounded apex, pointing towards the center of the disk (i.e., an axis of rotational symmetry of the disk). The position line then passes through this apex, or the point on the edge of the notch closest to the center.
[0020] If the position of a disk does not correspond to the desired or predetermined position, the invention proposes that the notch be enlarged such that the enlarged notch is positioned at the predetermined position with respect to the crystal orientation of the disk. As has been shown, enlarging the notch, i.e., further removing semiconductor material, allows the position of this notch—or rather, the enlarged notch—to be changed, in particular shifted in the circumferential direction of the disk. The position definition then applies accordingly to the enlarged notch. 202400022 / WH
[0021] 4
[0022] In one embodiment, the enlargement of the recess is achieved through an edge and recess rounding process. The rationale for such an edge and recess rounding process is that, after the crystal rod is cut, the edges of the individual discs are typically angular or sharp. Using suitable means, such as a grinding device, both edges (on the front and back of the disc) can be rounded simultaneously. The recess can also be rounded in this process. A more detailed explanation of an edge and recess rounding process can be found, for example, in DE 101 31 246 A1.
[0023] The usual procedure for such edge and recess rounding is to enlarge or grind down the recess uniformly, so that its position relative to the crystal orientation of the disk remains unchanged. This is also practical for the edge and recess rounding process itself, since it only involves rounding the edges and nothing else is to be altered.
[0024] It has now been shown that such an edge and recess rounding process is particularly well suited to changing the position of the recess relative to the crystal orientation of the disk when the recess is enlarged (by grinding down the edges, including those within the recess). For this purpose, the recess is enlarged or ground down unevenly on both sides, thereby shifting its position circumferentially. This is also illustrated in the following drawings.
[0025] To determine precisely how the position of the recess should be changed in relation to the crystal orientation of the disk, it is advisable to first ascertain the deviation of the disk's current position (actual position) from the predetermined position (target position) with respect to the crystal orientation. The recess can then be enlarged based on this deviation. An X-ray image of the disk can be used for this purpose; an X-ray image allows for a particularly accurate determination of the crystal orientation and thus the current position. This then enables the appropriate use of a grinding device to adjust the position of the recess on the disk accordingly. 202400022 / WH
[0026] 5
[0027] The invention relates, in addition to the method mentioned, to a device for adjusting the position of the recess on the outer circumference of a disk made of a semiconductor material. The preceding explanations and features and advantages of the method also apply accordingly to the device.
[0028] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing.
[0029] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified, but also in other combinations or on their own, without leaving the scope of the present invention.
[0030] The invention is schematically illustrated in the drawing using an exemplary embodiment and is described below with reference to the drawing.
[0031] Character description
[0032] Figures 1 to 8 schematically show a process in one embodiment with devices that can be used therein.
[0033] Figure 1 schematically shows a crystal rod 100, e.g., a single crystal, made of the semiconductor material; it could, for example, be a silicon crystal rod. The crystal rod 100 has a rotational symmetry axis and a longitudinal axis A. The crystal rod 100 could, for example, have been obtained by the Czochralski method or the floating-zone method, which, however, is not of particular interest to the present invention. The crystal rod is shown here as a cylinder. For this purpose, the crystal rod could, for example, have been machined at the ends and on the circumference. A circumferential direction is here designated by U.
[0034] Figure 1 further shows a device 200 by means of which a groove can be produced on an outer surface of the crystal rod 100, running along a longitudinal axis A of the crystal rod 100. For this purpose, the device 200 includes, by way of example, a clamping mechanism 210 by means of which the crystal rod 100 can be clamped at both ends, viewed in the direction of the longitudinal axis A, and optionally rotated about the longitudinal axis A. 202400022 / WH
[0035] 6
[0036] The device 200 includes a determining means 220, e.g., an X-ray device, with which a crystallographic orientation of the crystal rod 100 can be determined. The device 200 also includes an abrasive 230, e.g., a grinding wheel, by means of which the aforementioned groove can be made in the crystal rod.
[0037] As mentioned, the groove is to be produced in a specific, predetermined position with respect to the crystal orientation of the crystal rod 100. This refers to the position in the circumferential direction U. By determining the current crystallographic orientation of the crystal rod 100 using the determining device 220 and the position of the abrasive 230 in the circumferential direction U, it may be necessary to rotate the crystal rod 100 in the circumferential direction and align it accordingly.
[0038] When the crystal rod 100 is aligned accordingly, the groove can be made using the abrasive 230. Figure 2 shows the crystal rod 100 again. The groove is labelled t104 here, and it is made on the outer surface 102 of the crystal rod 100 and runs along the longitudinal axis A of the crystal rod O.
[0039] The crystal rod 100 is then divided into a multitude of slices. Figure 3 shows a device 300 for this purpose, e.g., a sawing device. The device 300 has, for example, several saw wires, two of which are shown and one of which is labelled 310. With this, the crystal rod 100 can be divided or sawn into a multitude of slices, particularly perpendicular to the longitudinal direction A of the crystal rod 100.
[0040] Figure 4 shows, purely as an example, a disk 110 separated from the rest of the crystal rod 100; another disk is indicated – still attached to the crystal rod 100. The groove, i.e., the missing part of the crystal rod, remains in the disk 110 and is then referred to as a notch, or more generally, a recess. The recess of the disk 110 is labelled 114 here.
[0041] Figure 5 shows disk 110 in a slightly different view, separately and larger. The rotational symmetry and longitudinal axis A of the crystal rod also forms the rotational symmetry and longitudinal axis of disk 110. Furthermore, a front- 202400022 / WH
[0042] Figure 7 shows the side of disk 110, which is perpendicular to the rotational symmetry and longitudinal axis A. A reverse side opposite the front side is not visible. At this stage of the disk's development, however, it is not necessary to distinguish between a front and a reverse side; one can simply speak of two sides or tops.
[0043] The number 118 designates an edge of the disk 110, specifically the edge between the outer circumference 112 and the back side. Correspondingly, there is an edge between the outer circumference and the front side, which is not labeled here. This edge runs not only along the outer circumference but also along the recess 114. The position of the recess 114 is shown here in relation to a crystal orientation of the disk, which is given by the angle <p bezeichnet ist. Die Kristallorientierung als Referenz ist hier nicht gezeigt.
[0044] The position of the recess 114 with respect to the crystal orientation of the disk 110 is defined by a position line, denoted here by P, lying in the plane of the disk (e.g., in the plane of the front face) and running midway between two lateral boundaries of the recess 114. Typically, such a recess has a (lying in the plane of the disk) at least substantially triangular shape, with its apex or possibly rounded apex pointing towards the center M of the disk 110, i.e., towards the axis of rotational symmetry A. The position line P then passes through this apex or the point on the edge of the recess closest to the center.
[0045] The edges of the disc 110 are rounded. This also includes rounding the recess 114 and its edges, and is referred to collectively as the edge and recess rounding process. Figure 6 shows a device 400 for this purpose, which has a grinding unit 410 for an edge and recess rounding process of the disc. The grinding unit 410 has a larger grinding wheel 412 and a smaller grinding wheel 414. The larger grinding wheel 412 has a concave edge. When the larger grinding wheel 412 and / or the disc 110 are rotated about their respective axes of rotation, and the edge of the larger grinding wheel 412 is brought to the edge (outer circumference) of the disc 110, the edges of the disc 110 are rounded. 202400022 / WH
[0046] 8
[0047] Similarly, the edges in the area of the recess 114 of the disc 110 can be rounded with the smaller grinding disc 414. Here, understandably, only the smaller grinding disc 414 is rotated around its axis of rotation, not the disc 110. The smaller grinding disc 414 has a small diameter so that it fits into the recess 114. It should be noted that the dimensions in Figure 6 are not to scale; rather, Figure 6 serves only for illustration.
[0048] Here, the recess 114 is enlarged because material is removed. This is shown for a conventional case in Figure 7. There, a portion of the disk 110 is shown in a top view. The recess 114 is shown with the position line P, which indicates the position <p definiert. Es ist zu sehen, dass die Aussparung 114 eine zumindest im Wesentlichen dreieckige Form aufweist, wobei die Spitze in Richtung Mittelpunkt der Scheibe (hier nicht zu sehen) weist.
[0049] Furthermore, the position line P runs centrally between two lateral boundaries of the recess 114; these two lateral boundaries are here labelled 114.1 , 114.2 and are the sides adjacent to the apex of the triangular shape.
[0050] When rounding the edges of the recess 114, the same amount of material is conventionally removed from all sides of the recess. For this purpose, the disc is aligned as precisely as possible so that the center of the recess 114 is struck by the smaller grinding disc 414. This enlarges the recess 114 uniformly, resulting in an enlarged recess 116. The recess 114 is enlarged both towards the center of the disc and uniformly in both directions around its circumference.
[0051] The essentially triangular shape is retained in the enlarged recess 116; only the tip is rounded due to the radius of the smaller grinding wheel 414. The recess may also be rounded at the outer corners.
[0052] The position <p der vergrößerten Aussparung 116 in Bezug auf die Kristallorientierung der Scheibe 110 entspricht damit der Position <p der Aussparung 114. Für den Fall, 202400022 / WH
[0053] 9 that the position <p der Aussparung 114 genau einer vorgegebenen oder gewünschten Position entspricht, also wenn die Ist-Position der Soll-Position entspricht, ist dies kein Problem.
[0054] If, on the other hand, the position <p der Aussparung 114 nicht der vorgegebenen oder gewünschten Position entspricht, so kann dies im Rahmen der vorliegenden Erfindung korrigiert bzw. angepasst werden. Dies ist in Figur 8 gezeigt.
[0055] Here again a part of the disc 110 is shown in top view, as in Figure 7. The recess 114 is shown with the position line P, which indicates the position <p definiert. Die Aussparung 114 entspricht derjenigen gemäß Figur 7.
[0056] The enlarged recess 116, shown in Figure 8, is also obtained by enlarging the recess 114. However, here the recess 114 is enlarged such that the enlarged recess 116 is located at the position cp* specified with respect to the crystal orientation of the disk, i.e., a desired or target position. This specified position <p* ist über die Positionslinie P* definiert. Die vorgegebenen Position <p* ist gegenüber der vorher vorhandenen Position <p um Acp, also einen gewissen Winkel in Umfangsrichtung verschoben.
[0057] For this purpose, the disc 110 is no longer aligned so that the center of the recess 114 is struck by the smaller grinding disc 414, but rather the disc 110 is machined so that the center of the enlarged recess 116 to be obtained is shifted as desired. This means that more material must be removed from one side of the recess 114 than from the other side.
[0058] To align the disc 110 and the smaller grinding disc 414 accordingly, a determining device 420, in particular an X-ray device, can be used with the apparatus 400, as schematically shown in Figure 6. In this way, the current position cp or the deviation of the actual position cp from the target position or predetermined position cp* can be determined.
[0059] Figure 8 also shows that the proposed method allows the position of the recess on the outer circumference of the disc to be adjusted. 202400022 / WH
[0060] 10 can be adjusted, but not arbitrarily. The enlarged recess 116 can only be shifted to the extent that the recess 114 remains within the enlarged recess 116. It is conceivable that a certain area may also be needed for rounding the edges in the region of the recess 114. Therefore, the extent to which an adjustment is possible depends on the dimensions of the recess 114 and the dimensions of the enlarged recess 116. The dimensions of the grinding devices also have an influence on this.
[0061] As has been shown, for typical dimensions achievable with standard grinding equipment and permissible for subsequent use, an adjustment of up to 0.6° is possible, i.e., Acp < 0.6°. However, if the deviation between the actual and target positions is greater than the possible adjustment, it is still possible to bring the actual position closer to the target position than it was before the adjustment. This may still be sufficient for certain subsequent applications, or at least better than no adjustment at all.
Claims
202400022 / WH 11 Patent claims 1. Method for adjusting the position (cp) of a recess (114) on the outer circumference (112) of a disk (110) made of a semiconductor material, characterized in that, if the recess (114) is not arranged at a position (cp*) specified with respect to a crystal orientation of the disk, the recess (114) is enlarged such that the enlarged recess (116) is arranged at the position (q>*) specified with respect to the crystal orientation of the disk, or at least closer than before.
2. Method according to claim 1, wherein the position (cp) of the recess (114) and the enlarged recess (116) with respect to the crystal orientation of the disk (110) is each defined by a position line (P) lying in the plane of the disk, which runs centrally between two lateral boundaries (114.1 , 114.2) of the recess or the enlarged recess.
3. Method according to claim 2, wherein the position line (P) passes through a rotational symmetry axis (A) of the disk (110).
4. Method according to one of the preceding claims, wherein, prior to enlarging the recess, a deviation (Acp) of the current position of the disk with respect to the crystal orientation from the predetermined position is determined, based on which the recess (114) is enlarged such that the enlarged recess (116) is arranged at the predetermined position (cp*) with respect to the crystal orientation of the disk.
5. Method according to claim 4, wherein the deviation is determined by means of an X-ray image of the disk (110).
6. Method according to one of the preceding claims, wherein the enlargement of the recess is carried out as part of an edge and recess rounding process.
7. Method according to one of the preceding claims, wherein, in order to obtain the disk (110), a groove (104) is introduced on an outer surface (102) of a crystal rod (100) made of the semiconductor material, the groove extending along a longitudinal axis 202400022 / WH 12 (A) of the crystal rod, wherein the disk (110) is obtained by cutting the crystal rod (100), after introducing the groove (104), in particular perpendicular to the longitudinal direction (A) of the crystal rod, in particular into a plurality of disks.
8. Device (400) for adjusting a position (cp) of a recess (114) on the outer circumference (112) of a disk (110) made of a semiconductor material, wherein the device (400) is configured to enlarge the recess (114) such that the enlarged recess (116) is arranged at a position (q>*) predetermined with respect to the crystal orientation of the disk, or at least closer than before.
9. Device (400) according to claim 8, comprising a determining means (320), in particular an X-ray device, by means of which a deviation (Acp) of the current position (cp) of the disk (110) with respect to the crystal orientation from the predetermined position, or the current position (cp) of the disk, can be determined.
10. Device (400) according to claim 8 or 9, comprising a grinding device (410) for an edge and recess rounding process of the disc, wherein the device is configured to enlarge the recess (114) by means of the grinding device (410).