Processing of substrate semiconductor wafers
The method addresses the challenge of controlling both global warp and local nanotopography in semiconductor wafers by using a coating and grinding process with curved storage devices, resulting in improved planar parallelism and reduced curvature for epitaxial coating.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SILTRONIC AG
- Filing Date
- 2025-10-30
- Publication Date
- 2026-05-21
AI Technical Summary
Existing methods for processing semiconductor wafers fail to simultaneously improve both global warp and local nanotopography, leading to undesirable curvature that affects further processing, particularly in epitaxial coating.
A method involving a coating sequence followed by specific grinding processes using storage devices with curved surfaces to control curvature, ensuring planar parallelism and reduced nanotopography on both sides of the wafer.
Achieves a substrate semiconductor wafer with controlled warp and improved nanotopography, allowing for precise compensation of deformations during epitaxial coating, ensuring planar parallelism and nanotopography values below 15 nm.
Smart Images
Figure EP2025081440_21052026_PF_FP_ABST
Abstract
Description
[0001] Processing of substrate semiconductor wafers
[0002] Technical field
[0003] The invention relates to a method for processing a substrate semiconductor disk on a processing device using a grinding device, as well as the substrate semiconductor disk produced or processed thereby, and, starting from the processed substrate semiconductor disk, a method for producing a semiconductor disk with at least one epitaxial layer.
[0004] State of the art and technical task
[0005] Depending on the type and geometric shape of the coating and the substrate semiconductor wafer, coatings on semiconductor wafers can cause uncontrolled curvature of the global semiconductor wafer geometry, which is undesirable for further processing of the semiconductor wafer.
[0006] To reduce this problem, methods such as (i) single-side grinding for the targeted adjustment of a "global" curvature (a warp value) of a substrate semiconductor wafer, as described for example in EP0580162A1, are known from the prior art, so that the curvature direction is counteracted by subsequent coating steps in order to ultimately obtain, for example, an ideally plan-parallel epi-coated semiconductor wafer, or (ii) grinding methods on a substrate semiconductor wafer in a so-called Resiflat device using a resin layer on the side of the substrate semiconductor wafer facing away from the grinding device, which are intended to improve the local curvature (nanotopography) of the processed substrate semiconductor wafer.
[0007] However, the methods known from the prior art have the disadvantage that they either only improve the nanotopography (standardized in SEMI M78-0923 “Guide for determining nanotopography of unpatterned silicon wafers high volume manufacturing” 2010 I 2023) of a semiconductor wafer or substrate semiconductor wafer, or only improve the “global” warp (in the sense of warp as defined in “ASTM F657-92(1999) Standard Test Method for Measuring Warp and Total Thickness Variation on Silicon Wafers by Noncontact Scanning” and “ASTM F1390-02 Standard Test Method for Measuring Warp on Silicon Wafers by Automated Noncontact Scanning”) of a semiconductor wafer or substrate semiconductor wafer.
[0008] The present invention is therefore based on the objective, technical problem of providing a processing method for substrate semiconductor wafers, substrate semiconductor wafers, and, based on this, a manufacturing method for semiconductor wafers comprising a processed substrate semiconductor wafer and at least one epitaxial layer deposited thereon, which exhibits the aforementioned disadvantages to a lesser degree and which, in particular, produces in a simple manner a semiconductor wafer (i.e., a substrate semiconductor wafer with at least one epitaxial layer) with substantially plane-parallel sides of the semiconductor wafer and simultaneously exhibits low nanotopography (local curvature) at least on the uncoated side of the semiconductor wafer (i.e.,uncoated side of the substrate semiconductor disk) has, in particular has an improved nanotopography compared to a substrate semiconductor disk or semiconductor disk processed according to the prior art method to (i)
[0009] The problem is solved by a processing method of a substrate semiconductor disk according to claim 1, by the substrate semiconductor disk according to claim 7, by a manufacturing method of a semiconductor disk comprising a substrate semiconductor disk and at least one layer according to claim 10, and by a processing device according to claim 12.
[0010] Description of the invention
[0011] According to a first aspect, the invention therefore relates to a method for processing a substrate semiconductor disk on a processing device, comprising
[0012] • at least the following steps in a coating sequence:
[0013] - Applying a film to a coating surface of a coating device and applying a curable layer thereon, - Placing the substrate semiconductor disk onto the curable layer, wherein a first disk side of the substrate semiconductor disk faces the curable layer,
[0014] - Curing of the curable layer, in particular by means of UV irradiation, - Removal of the substrate semiconductor wafer including curable layer and film from the coating device,
[0015] • at least the following steps of an initial processing sequence:
[0016] - Placing the substrate semiconductor disk onto a first depositing surface of a first depositing device, wherein the first disk side is facing the first depositing surface,
[0017] - Building up intake pressure in the first storage device via a first intake unit,
[0018] - Suction of the curable layer, and in particular the substrate semiconductor disk, to the first depositing surface,
[0019] - Grinding a second side of the substrate semiconductor disk, the side facing away from the first side, over a first grinding head of a first grinding device,
[0020] - Removal of the substrate semiconductor wafer including curable layer and film from the first deposit surface,
[0021] - Detachment of the curable layer from the substrate semiconductor disk, in particular by clamping the film and mechanical peeling, and
[0022] • at least the following steps of a second processing sequence:
[0023] - Placing the substrate semiconductor disk onto a second storage surface of a second storage device, wherein the second disk side faces the second storage surface,
[0024] - Building up intake pressure in the second storage device via a second intake unit,
[0025] - Suction of the substrate semiconductor disk to the second placement surface, - Grinding of the first disk side over a second grinding head of a second grinding device,
[0026] - Removal of the substrate semiconductor disk from the second storage surface.
[0027] The invention is characterized in that at least one of the first and second storage surfaces is designed as a curved surface which, viewed along an associated radial axis through the associated storage device, forms a 2023P00024WG / HA
[0028] 4
[0029] an associated storage device contour is defined, wherein a projected contour diameter, viewed along the associated radial axis, is assigned a value of 300 mm to 320 mm, and wherein the course of the value of the curvature is at least sectionally, preferably predominantly, further preferably over the entire storage surface, viewed in a range of 7.81x10' 5 m' 1 up to 5.33x10' 3 m' 1 , preferably in the range of 3.12x10' 4 m' 1 up to 2.67x10' 3 m' 1 , preferably in the area of 5.47x10' 4 m' 1 up to 1.33x10' 3 m' 1 , lies.
[0030] This overcomes the aforementioned disadvantages with regard to the state of the art. In particular, it allows for the advantageous production of a substrate semiconductor wafer with targeted geometric processing (on its first and second wafer sides), the warp value of which can be specifically adapted to the deformations occurring during epitaxial coating in the subsequent manufacturing process due to thermal stresses. This ensures that, especially after epitaxial coating, an approximate compensation of the deformations or curvatures is achieved, resulting in essentially planar parallelism between the wafer sides of the epitaxially coated semiconductor wafer. Additionally, improved local curvature (nanotopography) is achieved on both wafer sides of the substrate semiconductor wafer.
[0031] After completion of the processing (grinding) process on the processing device, the substrate semiconductor wafer exhibits nanotopography values that do not exceed 15 nm, preferably 10 nm (e.g., measured and filtered by double Gaussian filtration in a circular, local window with a diameter of 25 mm (THA25) at each position of the substrate semiconductor wafer). The nanotopography measurement is standardized in SEMI M78-0923 "Guide for determining nanotopography of unpatterned silicon wafers high volume manufacturing" 2010 I 2023. The measurement method for THA25: An interferometer, for example, a WaferSight™ instrument from KLA-Tencor Corp., can be used to investigate the nanotopography. Such an interferometer is suitable for measuring the topography on the upper side surface of a substrate semiconductor wafer or semiconductor wafer. The instrument generates a height map of the upper side surface of the substrate semiconductor wafer or semiconductor wafer.A semiconductor disk is removed, filtered, and an analysis window with a defined analysis area is moved across it. The evaluation of the height differences in the analysis window is performed by THA (threshold height analysis) according to the procedures specified in standards SEMI M43-0418 and SEMI M78-0618.
[0032] In further advantageous variants, a first storage device can be selected whose first storage surface, viewed along a first radial axis through the first storage device, defines a first storage device contour, wherein the course of the value of the curvature within at least one concave and / or within at least one convex curved section in the range of 7.81x10' 5 m' 1 up to 5.33x10' 3 m' 1 , preferably in the range of 3.12x10' 4 rrr 1 up to 2.67x10' 3 m' 1 , preferably in the range of 5.47x10'4 rrr 1 up to 1.33x10' 3 m' 1 , lies. Additionally or alternatively, a second storage device can be selected whose second storage surface, viewed along a second radial axis through the second storage device, defines a second storage device contour, wherein the course of the value of the curvature within at least one concave and / or within at least one convex curved section in the range of 7.81x10' 5 rrr 1 up to 5.33x10' 3 m' 1 , preferably in the range of 3.12x10' 4 rrr 1 up to 2.67x10' 3 m' 1 , preferably in the range of 5.47x10' 4 rrr 1 up to 1.33x10' 3 rrr 1, lies. Thus, by applying the described processing method, a large number of global substrate semiconductor wafer geometries can be easily achieved by specifically selecting the geometry of the depositing surface of the chosen depositing device for the two processing sequences.
[0033] Preferably, the first storage device contour of the first storage device is assigned a (projected) first contour diameter, viewed along the radial axis, which has a value in the range of 300 mm to 320 mm. The first contour diameter preferably takes on a value in the range of 302 mm to 315 mm, and more preferably from 305 mm to 310 mm.
[0034] It is understood that the first storage device as a whole may have a diameter that exceeds the contour diameter (i.e., the first storage device may terminate radially outwards with a substantially planar, annular surface). Preferably, the contour of the second storage device is assigned a (projected) second contour diameter, viewed along the radial axis, which has a value in the range of 300 mm to 320 mm. The second contour diameter preferably has a value in the range of 302 mm to 315 mm, and more preferably from 305 mm to 310 mm.
[0035] It is understood that the second storage device as a whole may have a diameter that exceeds the contour diameter (i.e., the second storage device may terminate radially outwards with an essentially flat, ring-shaped surface).
[0036] In the simplest case, the respective storage device contour in radial section essentially follows a (single) circular arc segment in the form of a circle of curvature along the contour diameter and has an associated section height H (i.e., in principle, represents a circular segment in radial section).
[0037] With reference to the illustration in Figure 1, the following simplified geometric relationship between the radius of curvature, section height, and chord length can be assumed, whereby a relationship can be established for the present invention between the section height H of a storage device, a projected length or a projected contour diameter (the latter applies in the simplest case when the curvature contour can be described with a single circle of curvature along the entire diameter of the storage device; in the sense of a chord length s of the circle of curvature) and a radius of curvature R of the circle of curvature.The current curvature value is the reciprocal of the current radius of curvature R of a currently assigned circle of curvature and, in the simplest case (when the surface contour of the storage surface follows a single circle of curvature), is essentially a constant value over the storage surface viewed in radial section. (For a piecewise varying curvature contour, the following relationship applies analogously for each section (i.e., each projected length) individually):.
[0038]
[0039] 2023P00024WC / HA
[0040] 7
[0041] For example, for a projected contour diameter of the associated storage device of 300 mm with a section height H of (a) 1.5x10' 5 m, (b) 3,0x10' 5 m, (c) 6,0x10' 5 m of the curved surface of the storage device the curvature value (a) 1.33x10' 3 m' 1 or (b) 2.67x10' 3 m' 1or (c) 5.33x10' 3 m' 1 be.
[0042] Alternatively, for example, a projected contour diameter of the associated storage device of 320 mm with a section height H of (a) 1.0x10' can be used. 6 m, (b) 4,0x10' 6 m, (c) 7,0x10' 6 m of the curved surface of the storage device the curvature value (a) 7.81x10' 5 m' 1 or (b) 3.12 x 10' 4 m' 1 or (c) 5.47x10' 4 m' 1 be.
[0043] Preferably, one of the two storage devices is concave and the other of the two storage devices is convex.
[0044] It is understood that the terms "first" and "second" sides of the disc are not, in themselves, defined or assigned to a fixed processing state of the disc side, since the surface condition of the first and second sides of the disc changes according to the invention during the processing sequence of the grinding process (in the sense of a surface improvement). The terms themselves therefore merely characterize a geometric relationship.
[0045] The process flow between the coating sequence and the first and second processing sequence using the coating device, the first and second storage device, or the spatial arrangement of the coating device, the first and second storage device within the processing device, can in principle be designed arbitrarily.
[0046] Preferably, the coating device is located at a prominent position within the processing device (serial production), away from the first and second loading devices. Preferably, the loading device (the "chuck") is exchanged between processing sequences (i.e., in the second processing sequence, the second loading device is used in place of the first, after the first loading device has been removed). It is also conceivable that the substrate semiconductor wafer for the second processing sequence is placed in a second loading device within the processing device, which is located at a prominent position within the processing device, away from the first loading device.Furthermore, it is conceivable that the first and second storage devices are mounted in a common receiving device, which is rotatably mounted about its vertical axis and / or is longitudinally displaceable, so that, depending on the process stage, either the first or the second storage device is positioned under the grinding device. The processing device is therefore preferably designed and configured to be able to provide each of these process variants.
[0047] Preferably, the coating device used is provided with a substantially flat coating surface, so that after curing, a composite of film, curable layer, and substrate disc is formed, which has a substantially flat surface on the free side of the film that runs substantially parallel to the free surface (of the second side of the disc). This embodiment is particularly preferred for the subsequent processing sequence(s), in which this composite then conforms to the shape of the respective processing surface of the respective processing device via the activation of the respective suction unit and provides a reproducible contour of the free side of the substrate disc, which is currently being processed by the grinding device, in relation to the selected film-side depositing device contour of the depositing surface.
[0048] In alternative designs, however, it is also conceivable to use a coating device in the coating sequence whose coating surface is already provided with a curved surface, which, viewed along an associated radial axis through the coating device, is defined by a specifically selected depositing device contour and is specifically coordinated with the shapes of the depositing surfaces of the first and second depositing devices used subsequently.
[0049] Preferably, the coating device is made of glass. However, any other material can also be used, provided it is transparent for the preferred curing process by UV light. For curing not induced by UV light, for example thermally or by using a two-component resin, any other non-transparent material can be used. The coating sequence is essentially as known from the prior art, and therefore these steps will not be described in detail.
[0050] It is understood that within the first and second processing sequences, the grinding step is only initiated when the substrate semiconductor wafer is in its suction position. Preferably, this is achieved after a minimum suction time of less than one (1) second, although the invention is not limited to this value. Preferably, the position can also be monitored optically by means of camera monitoring before the respective grinding step is initiated.
[0051] The removal process is carried out using a known technological method, in particular by mechanically gripping and peeling the film, so it will not be discussed in detail here. Preferably, the removal takes place outside the processing device. In other variants, the curable layer may be provided at a suitably configured point (along the production line) within the processing device.
[0052] In other variants, it may be provided that the second processing sequence is immediately preceded by another coating sequence in which another curable layer and another film are applied to the second deposit surface, resulting in the following steps after completion of the first processing sequence:
[0053] • at least the following steps in the further coating sequence: - Applying another film to another coating surface of another coating device and applying another curable layer thereon,
[0054] - Placing the substrate semiconductor disk onto the further curable layer, with the first disk side of the substrate semiconductor disk facing the further curable layer,
[0055] - Curing of the next curable layer,
[0056] - Removal of the substrate semiconductor wafer including further curable layer and further film from the further coating device, and
[0057] at least the following steps of the second processing sequence: - Placing the substrate semiconductor disk onto the second storage surface of the second storage device, with the second disk side facing the second storage surface,
[0058] - Building up intake pressure in the second storage device via the second intake unit,
[0059] - Suction of the substrate semiconductor disk to the second placement surface, - Grinding of the first disk side over the second grinding head of the second grinding device,
[0060] - Removal of the substrate semiconductor disk from the second deposit surface, - Detachment of the further curable layer from the substrate semiconductor disk.
[0061] The curable layer and / or the further curable layer can have a thickness in the range of 2 pm to 150 pm, preferably in the range of 30 pm to 100 pm. In particular, synthetic resins can be used as materials for the curable layer, which cure either upon exposure to light or by crosslinking two resin components. Materials that cure by a change in temperature or state of matter are also possible. However, the invention is in no way limited to these materials or thicknesses.
[0062] The film and / or the further film preferably comprise the material polyethylene or any other plastic.
[0063] The first and / or second storage device can be designed as an interchangeable, modular unit and detachably mounted on a substructure, for example, on a rotatable and / or linearly movable fixture. This ensures quick and flexible changing of the storage device to the required geometry or warp value of the substrate semiconductor wafer being processed.
[0064] In further advantageous variants, one of the two storage devices can be selected with a storage surface that is at least partially, preferably predominantly, and more preferably substantially over the entire storage surface, and one of the two storage devices can be selected with a substantially flat surface. 2023P00024WQ / HA
[0065] 11
[0066] In further advantageous variants, one of the two storage devices can be selected with a storage surface that is at least partially, preferably predominantly, and more preferably substantially convex over the entire storage surface, and one of the two storage devices can be selected with a substantially flat plane.
[0067] Thus, by applying the inventive method or one or more of the variants described above, after completion of the second processing sequence, a substrate semiconductor disk is ultimately produced by the specific selection or geometric design of the first and second (depositing surface of the) depositing device, the curvature profile of which is controlled and set on the first and second disk sides.
[0068] The substrate semiconductor disk obtained after the second processing sequence thus preferably has a global grinding target geometry with a contour on both sides of the disk, the (absolute) course of the curvature value is specifically set by the selection and combination of the first and second depositing device geometry and is particularly in the range of 7.81x10' 5 rrr 1 up to 5.33x10' 3 rrr 1 , preferably in the range of 3.12x10' 4 rrr 1 up to 2.67x10' 3 rrr 1 , preferably in the area of 5.47x10' 4 rrr 1 up to 1.33x10' 3 rrr 1 , lies.
[0069] The advantages of the invention are particularly evident when the grinding step of the first and second machining sequences is performed as a surface grinding step using a grinding device in the form of a surface grinding device with a substantially flat grinding head, as this allows for particularly simple and well-known designs of the machining device on the grinding device side. However, the invention is not limited to this, and designs of the machining device are also conceivable in which, for example, the respective grinding head is not substantially flat but deliberately curved (and, in particular, is rotatably mounted about its vertical axis).
[0070] Furthermore, advantageous variants are conceivable with targeted and rapid processing of the disc side to be ground during the associated processing sequence, in which the inclination of the feed axis of the grinding head assigned to the grinding device changes during the grinding step to process the facing disc side.It may therefore be provided that for the grinding step during the first and / or second processing sequence a detachably mounted (first and / or second) grinding head is selected as part of the associated grinding device, which is designed as a flat grinding wheel or cup wheel, wherein during the grinding step the feed axis of the respective grinding head is inclined relative to a rotation axis of the associated storage device by a feed angle and this feed angle is varied during the grinding step to process the facing disc side of the substrate semiconductor disc in order to grind a predefinable globally curved geometry of the facing disc side.In combination with one of the above-mentioned variants of the geometric design of the first and / or second storage surface geometry on the side of the storage device, the simultaneous possibility of adjusting the feed angle on the side of the grinding device for processing the facing disc side further expands the range of achievable global substrate disc geometries.This variant is particularly advantageous when the variable feed axis is used to machine the facing disc side to a globally curved geometry in a first machining sequence, in conjunction with a first storage device that is essentially flat. This ensures that the resulting curved, ground disc side experiences virtually no preload during this machining sequence, preventing springback after completion. Consequently, the geometry of this disc side essentially corresponds to the geometry of the disc side after removal following this machining sequence, making it easily reproducible. The second machining sequence can then involve the use of a second machining device that, as described above, has a flat or at least partially concave and / or convex storage surface.
[0071] In other preferred variants, the first grinding head physically corresponds to the second grinding head, and thus the first grinding device physically corresponds to the second grinding device, resulting in a simple and compact design of the machining device.
[0072] In other variants, it is conceivable that (i) the first grinding head does not physically correspond to the second grinding head, and (ii) these two either have an substantially identical shape or a different shape (e.g., both are designed as cup wheels or one as a cup wheel and one as a surface grinding wheel), and (iii) they are spatially exposed, mounted in their different grinding fixtures, and positioned and aligned with the location of the associated storage device (production line; preferred variant in the case that one of the grinding heads is operated via a variable feed axis relative to the height axis during the grinding step), or both are mounted within a magazine and then, as required, moved and positioned via the currently used storage device according to the machining sequence (i.e.,(which, apart from the magazine, basically means that the first and second processing devices coincide).
[0073] The first and second storage devices and the respective grinding head of each grinding device rotate about their respective axes of rotation or vertical axis, preferably at rotational speeds customary in the art. For example, the rotational speed of the first and second storage devices can be in the range of 10 rpm (rounds per minute) to 200 rpm, and the rotational speed of the respective grinding head (designed as a cup wheel or surface grinding wheel) can be in the range of 1000 rpm to 10000 rpm. The selected values can also be varied depending on the machining sequence, particularly if a machining sequence is chosen in which the respective grinding head processes the facing side of the wheel at an infeed angle (relative to the vertical axis or rotational axis of the associated storage device), as described above.
[0074] As already explained above, the inventive method described above, or in combination with one or more of its advantageous variants, directly produces a substrate semiconductor wafer with a specifically geometrically machined surface (on its first and second wafer sides). The warp value of this wafer can be specifically adapted to the deformations occurring during epitaxial coating in the subsequent manufacturing process due to thermal stresses. This ensures that, particularly after epitaxial coating, the deformations or warps are approximately compensated, and essentially planar parallelism prevails between the wafer sides of the epitaxially coated semiconductor wafer. Additionally, it was recognized that improved 2023P00024WG / HA
[0075] 14
[0076] Nanotopography values (local curvatures) are obtained on both sides of the substrate semiconductor disk.
[0077] According to a further aspect, the invention therefore relates to a substrate semiconductor wafer with a nominal diameter of essentially 300 mm, wherein the substrate semiconductor wafer has a global grinding target geometry with at least one section having a warp value in the range of 1 pm to 60 pm, preferably in a range of 4 pm to 30 pm, more preferably in a range of 7 pm to 15 pm, and wherein the nanotopography values on each of the two wafer sides, in particular measured and filtered by double Gaussian filtration in a round, local window with a diameter of 25 mm according to SEMI M78-0923 - Guide for determining nanotopography of unpatterned silicon wafers high volume manufacturing - 2010 / 2023, do not exceed a value of 15 nm, preferably 10 nm, at each position of the wafer sides of the substrate semiconductor wafer.
[0078] In preferred embodiments, the first side of the disk can be at least sectionarily concave and / or at least sectionarily convex. Additionally or alternatively, the second side of the disk can be at least sectionarily concave and / or at least sectionarily convex.
[0079] In other words, the resulting disk side curvature contour of each disk side on the substrate semiconductor disk results from the targeted choice of the geometry of the depositing devices and the choice of the combination of the first and second depositing devices and the sequence of the processing operations.
[0080] According to a further aspect, the invention relates, starting from the processed substrate semiconductor wafer according to the invention or one of its advantageous variants, to a method for producing a semiconductor wafer comprising the processed substrate semiconductor wafer with at least one epitaxial layer, wherein – starting from the processing method according to the invention described above (or preferred variants thereof) – after removal of the substrate semiconductor wafer from the processing device after completion of the second processing sequence, the substrate semiconductor wafer has a global grinding target geometry with at least one section having a warp value in a range of 1 pm to 60 pm, preferably in a range of 4 pm to 30 pm, and more preferably in a range of 7 pm to 15 pm.
[0081] - following the extraction, at least one etching step of the substrate semiconductor disk is performed,
[0082] - and then at least one polishing step on the first and / or the second side of the disk follows on a polishing device, wherein during the at least one polishing step the substrate semiconductor disk on the first and / or the second side of the disk is selectively polished via the polishing device with a local polishing removal on the substrate semiconductor disk on the relevant side of the disk,
[0083] - and in particular at least one cleaning step of the substrate semiconductor disk is then carried out,
[0084] - and then a layer is deposited on at least one side of the substrate semiconductor disk, whereby
[0085] o on one of the two disk sides (i.e. the first or second disk side) of the substrate conductor disk, at least one epitaxial layer is deposited within an epitaxial device, wherein the at least one epitaxial layer comprises in particular GaN and / or silicon,
[0086] o and, prior to that time, a low thermal oxide layer is applied, particularly on the other side of the substrate semiconductor disk.
[0087] This overcomes the aforementioned disadvantages with regard to the state of the art. In particular, the method described above, in combination with the previously targeted processing of the substrate semiconductor wafer in the upstream processing process of the substrate semiconductor wafer, achieves an (approximate) compensation of the deformations or curvatures on the epitaxially coated semiconductor wafer and essentially achieves planar parallelism between the wafer faces of the epitaxially coated semiconductor wafer after removal from the epi-reactor.In addition or alternatively to these advantageous variants, at least one epitaxial layer can be applied locally to the substrate semiconductor wafer in such a way that a predefinable target thickness of the produced semiconductor wafer in the range of 600 pm to 1000 pm is achieved and / or the produced semiconductor wafer (after removal from the epi-reactor and reduction of thermal stresses) has a warp value of less than 4 pm.
[0088] Finally, the invention relates to a processing device designed for processing a substrate semiconductor disk according to the invention (or one of its variants), comprising
[0089] - at least one grinding head on an associated at least one grinding device, wherein the at least one grinding head is preferably a detachably mounted grinding head, in particular in the form of a flat grinding wheel or cup wheel,
[0090] and
[0091] - at least one coating device with an associated coating surface,
[0092] - a first storage device with a first storage surface and a first intake unit,
[0093] - a second storage device with a second storage surface and a second intake unit.
[0094] According to the invention, at least one of the first and second storage surfaces is designed as a curved surface, wherein, viewed along an associated radial axis through the associated storage device, an associated storage device contour is defined, the course of the value of the curvature being at least sectionally, preferably predominantly, and further preferably over the entire storage surface, in a range of 7.81x10' 5 m' 1 up to 5.33x10' 3 m' 1 , preferably in the range of 3.12x10' 4 m' 1 up to 2.67x10' 3 m' 1, preferably in the area of 5.47x10' 4 m' 1 up to 1.33x10' 3 m' 1 , lies.
[0095] The depositing device (the "Chuck") is designed in a known manner with regard to its integrated intake unit and, more generally, its function, so that its design will not be discussed in detail. The intake pressures and times are also within the ranges known from the prior art. The intake time can be further selected depending on the degree of curvature of the depositing surface, but even in this case, it preferably remains within the usual range of < 1 sec; however, a range above or below this can also be selected in individual cases, and the invention is not thereby limited.
[0096] In other words, the curvature of the storage surface according to the invention advantageously has a negligible influence on the duration of the respective first and second processing sequences.
[0097] The features and advantages described above in connection with the method according to the invention (or one of its preferred variants) apply equally to the machining device designed to carry out the machining process according to one of the variants described above. To avoid repetition, reference is made to the above explanations.
[0098] Brief description of the characters
[0099] Figure 1 shows, in a highly schematic manner and with the curvature contour greatly exaggerated and the radius of curvature greatly understated, the simplified assumed relationship between circle of curvature R, section height H and chord segment s (here, for simplicity, exactly corresponding to the contour diameter of the storage device) for determining the curvature contour, where the (local) curvature corresponds to the reciprocal of the (local) radius of curvature.
[0100] Figure 2 schematically shows a preferred embodiment of the inventive machining process of a substrate semiconductor disk on a preferred embodiment of the inventive machining device during individual machining steps within (af) of the first machining sequence, and within (gj) of the second machining sequence, wherein Figure 2(j) schematically shows the achieved, global final geometry of the machined substrate semiconductor disk after removal from the machining device after completion of the second machining sequence in the relaxed state.Figure 3 schematically shows an alternative variant to Figure 2 for the setup and execution of a first machining sequence in a state of the first machining sequence towards the end of the grinding step, in which a specifically defined, curved contour is set during grinding on the side of the disc to be ground by varying the feed axis of a first grinding head.
[0101] Detailed description of preferred embodiments
[0102] Preferred embodiment
[0103] In the following, a preferred embodiment of the processing method according to the invention is described on a substrate semiconductor disk (1) within a processing device (100) according to the invention, wherein the substrate semiconductor disk (1) is subsequently fed to the manufacturing process according to the invention for the production of a semiconductor disk (10) with a deposited epitaxial layer (2).
[0104] The following steps of a coating sequence are carried out within the processing device:
[0105] - Applying a film to a coating surface of a coating device made of glass, and then applying a curable layer to it,
[0106] - Placing the substrate semiconductor disk (1) onto the curable layer, wherein a first disk side (1.1) of the substrate semiconductor disk (1) is facing the curable layer,
[0107] - Curing of the curable layer by UV irradiation (in a known manner), - Removal of the substrate semiconductor disk (1) including curable layer and film from the coating device,
[0108] The coating sequence is carried out in a known manner and is therefore not shown separately in Figure 2. The semiconductor wafer is then transferred within the processing device to a further station, where the first storage device is located and where the grinding process according to the invention now begins.
[0109] The following steps are carried out within the initial processing sequence:
[0110] - Placing the substrate semiconductor disk (1) onto a first depositing surface (101.1) of a first depositing device (101), wherein the first disk side (1.1) faces the first depositing surface (101.1) (see Figure 2(a)), - Building up a suction pressure in the first depositing device (101 ) via a first suction unit,
[0111] - Suction (indicated by arrows in Figure 2(b)) of the curable layer, and in particular the substrate semiconductor disk (1), onto the first depositing surface (101) (built-up suction pressure until a suctioned position is reached, see Figure 2(b)),
[0112] - Grinding a second (1.2) side of the substrate semiconductor disk (1) opposite the first (1.1) side of the disk over a first grinding head (103.1) of a first grinding device (103), wherein this grinding head (103.1) is detachably mounted on the rest of the grinding device (103) and is designed as a cup wheel (see Figure 2(c)),
[0113] - Removal of the substrate semiconductor disk including curable layer and film from the first deposit surface (101.1), see Figure 2(d).
[0114] - Detachment of the curable layer from the substrate semiconductor disk (1), see Figure 2(e).
[0115] In the present embodiment, the detachment of the curable layer takes place outside the processing device. In other variants, the curable layer may be located at a suitably configured point within the production line of the processing device.
[0116] Figure 2(b) shows the suctioned state of the curable layer and the substrate semiconductor disk (1) against the first deposit surface (101.1).
[0117] With regard to its first storage surface side, the first storage device (101) is concave, as shown in Figure 2. The storage device contour of the first storage device (101) at its first storage surface (101.1) is shown in the radial section of the first storage device in Figure 2(a) to Figure 2(d).
[0118] This first storage device contour is associated with a (projected) first contour diameter, viewed along the radial axis, which has a value of essentially 305 mm. In the present embodiment, the storage device contour in radial section essentially follows a circular arc segment along the contour diameter, and the first storage device has a section height H of 3.00 x 10'. 5 m on. With reference to Figure 1 and the simplified assumed relationship between radius of curvature, section height and chord length (here contour diameter)
[0119]
[0120] For the present embodiment, this results in a value of the (local) curvature (as the reciprocal of the (local) radius of curvature), which is essentially constant over the curvature contour, of 2.58x10' 3 m' 1 .
[0121] In the present embodiment, the diameter of the first storage device essentially corresponds to the first contour diameter (i.e., the first storage device closes radially outwards with the curvature contour).
[0122] It is understood that in other preferred variants of the invention other curvature ranges or contours are conceivable, particularly in a range of 7.81x10' 5 m' 1 up to 5.33x10' 3 m' 1The curvature can vary, particularly along the contour of the storage device (so that the contour of the storage device does not follow a circular arc segment in radial section). It is further understood that in other variants, the first storage surface may be additionally or alternatively convex, at least in certain sections.
[0123] Figure 2(c) shows the grinding step within the first machining sequence.
[0124] Arrows in Figures 2(b) to (d) (and for the second processing sequence, Figure 2(h)) indicate elastic deformations (prestresses) of the substrate semiconductor wafer during the respective steps. 2023P00024WG / HA
[0125] 21
[0126] After the removal and detachment step of the first processing sequence, the substrate semiconductor disk is brought into a relaxed state, Figure 2(e), since the preload applied to the substrate semiconductor disk as a result of the suction process and grinding process was reduced by springback after completion of the processing sequence.
[0127] After completion of the first processing sequence (Figure 2(a) to Figure 2(e)) and after turning the substrate semiconductor wafer (Figure 2(f)), the steps of a second processing sequence are carried out. In the present embodiment, no further curable layer or film is applied during the second processing sequence. Therefore, the following steps occur during the second processing sequence (Figure 2(g) to Figure 2(j)) after the first processing sequence:
[0128] - Placing the substrate semiconductor disk (1) onto a second storage surface (102.1) of a second storage device (102), wherein the second disk side (1.2) faces the second storage surface (102.1), - Building up suction pressure in the second storage device (102) via a second suction unit,
[0129] - Suction of the substrate semiconductor disk (1) to the second deposit surface (102.1),
[0130] - Grinding the first side of the disc (1.1) over a second grinding head (104.1) of a second grinding device (104),
[0131] - Removal of the substrate semiconductor disk (1) from the second storage surface.
[0132] In other preferred variants, it may alternatively be provided that during the second processing sequence another film and another curable layer are applied and the steps of the second processing sequence change accordingly.
[0133] In the present embodiment, a second storage device (the "chuck") is specifically selected, the second storage surface (102.1) of which is essentially planar. In other words, by selectively choosing and coordinating the geometry of the first and second storage devices, a targeted adjustment of the overall final geometry can be achieved with simple means, without having to extensively modify the process control of the machining device for grinding processes. It is understood that in other preferred embodiments of the invention, curvature ranges are conceivable, particularly in a range of 7.81 x 10⁻⁶. 5 m' 1 up to 5.33x10' 3 rrr 1 It is further understood that in other variants the second depositing surface (102.1) may be concave and / or convex, at least in sections, depending on the requirements of the global final geometry after processing of the substrate semiconductor disk (1).
[0134] After completion of the second processing sequence, after the reduction of the prestress or springback to a relaxed state, a globally curved substrate semiconductor disk (1) (nominal diameter 300 mm) is ultimately produced, as shown in Figure 2(j), which is convexly curved on its processed first disk side (1.1) and concavely curved on its processed second disk side (1.2) and has a “bowl” shape, as shown in Figure 2(j).In this state, the substrate semiconductor wafer exhibits a global grinding target geometry with a warp value of essentially 7 pm and has nanotopography values at each position of the two wafer sides, measured and filtered by double Gaussian filtration in a round, local window with a diameter of 25 mm according to SEMI M78-0923 - Guide for determining nanotopography of unpatterned silicon wafers high volume manufacturing - 2010 / 2023, which do not exceed a value of 10 nm.
[0135] In the present embodiment, the first (101) and second (102) storage devices are each designed as interchangeable, modular units and are detachably mounted on a substructure on a rotatably movable receiving device of the processing device (not shown in Figure 2). During the transition from the first to the second processing sequence, the second storage device (102) is moved into position under the grinding device (103) by rotating the receiving device, and then the second disk side (1.2) of the substrate semiconductor disk (1) is processed on the second storage device (102) according to the second processing sequence. The chosen design ensures a quick and flexible change of the storage devices to the required geometry or warp value of the substrate semiconductor disk (1) being processed.It is understood that in other preferred variants, other connection options for the storage devices are possible, or, for example, the first and second storage devices are positioned spatially separated from each other.
[0136] The suction pressure and suction time within the first and second processing sequences, or at the first (101) and second (102) depositing device, are, in the present embodiment, usual values known from the prior art, with a suction time of less than one (1) second. It is understood that higher or lower values for the suction time are applicable instead and that the invention is not limited to these values.
[0137] The first (101) and second (102) storage devices and the first (103.1) and second grinding heads (104.1) (which, as explained above, are physically identical in the present embodiment, meaning that the first grinding device (103) is physically identical to the second grinding device (104)) rotate about their respective axes of rotation or height at rotational speeds customary in the prior art. The rotational speed of the first and second storage devices is in the range of 10 rpm to 200 rpm (specifically, 100 rpm in this embodiment), and the rotational speed of the grinding head (designed as a cup wheel in the present embodiment) is in the range of 1000 rpm to 10000 rpm (specifically, 2000 rpm in this embodiment). In other preferred variants, the selected values can also be varied depending on the machining sequence.
[0138] In other preferred embodiments of the invention, it is also possible to select a first or second machining sequence in which the associated grinding head (103.1 or 104.1) processes the second disc facing the workpiece to a curved surface via an infeed angle (an infeed axis inclined relative to the height axis or rotation axis of the associated storage device) that varies over the grinding step.
[0139] Preferably, this alternative configuration is provided in a first processing sequence in conjunction with a substantially planar first storage device, wherein in the second processing sequence a planar or at least partially concave and / or convex curved storage device is selected and 2023P00024WQ / HA
[0140] 24
[0141] The feed axis of the grinding head is selected to be essentially parallel to the rotation axis of the second storage device, as is otherwise customary. Figure 3 schematically shows, for this preferred alternative embodiment of the first machining sequence, a state towards the end of the grinding step in which a specifically predetermined, curved contour is set during grinding by varying the feed axis of a first grinding head (105.1) during grinding (compare with the grinding steps in Figure 2(c) and Figure 2(i) of the preferred embodiment with a feed axis of the first grinding head (103.1) that, in a known manner, runs essentially parallel to the rotation axis of the respective storage device).In this alternative preferred embodiment, the feed axis of the grinding wheel is inclined during the first grinding step, and during the second grinding step, the feed axis is positioned substantially parallel to the rotation axis of the second storage device. (As a further alternative to the embodiment shown in Figure 3, it is conceivable that two physically distinct grinding heads are used for the two machining sequences, each with different positions of the feed axes relative to the rotation axis of the storage device. Another alternative would be to adjust the position of the rotation axis of the storage device instead of the position of the feed axes of the grinding head.)
[0142] In the present embodiment, following processing on the processing device (100) and after removal from the processing device (100), the processed substrate semiconductor disk (1 ) is coated with an epitaxial layer (3) comprising silicon, wherein the following manufacturing steps are carried out on the substrate semiconductor disk before the epitaxial coating:
[0143] • Following the removal, an etching step of the substrate semiconductor disk (1) is carried out, and then a polishing step is carried out on the first (1.1) and the second (1.2) disk side using a polishing device, wherein during the polishing step the substrate semiconductor disk on the first (1.1) and the second (1.2) disk side is selectively polished by the polishing device with a local polishing removal on the substrate semiconductor disk (1) on the respective disk side.
[0144] • Next, the substrate semiconductor wafer (1) undergoes a cleaning step. • A low thermal oxide layer (2) is then applied to the second side (1.2) of the substrate semiconductor wafer (1).
[0145] • Next, the substrate semiconductor disk (1) is placed into a hole susceptor in an epi-reactor (with the second disk side (1.2) facing the hole susceptor recess) and the epitaxial layer (3) comprising silicon is deposited on the first disk side (1.1).
[0146] The epitaxial layer (3) is applied locally to the substrate semiconductor disk (1) until a predefinable target thickness of the produced semiconductor disk (10) in the range of approximately 800 pm is achieved and the produced semiconductor disk (10) (after removal from the epi-reactor and reduction of thermal stresses) has a warp value of approximately 3 pm.
[0147] Thus, after epitaxial coating, an approximate compensation of the deformations or curvatures caused by thermal stresses during epitaxial coating was achieved, or essentially planar parallelism between the outer surfaces (10.1, 10.2) of the epitaxially coated semiconductor disk (10) was achieved.
[0148] The invention is not limited to the preferred embodiment described above.
Claims
26 Patent claims 1. Method for processing a substrate semiconductor wafer (1) on a processing device, comprising • at least the following steps in a coating sequence: - Applying a film to a coating surface of a coating device and applying a curable layer thereon, - Placing the substrate semiconductor disk (1) onto the curable layer, wherein a first disk side (1.1) of the substrate semiconductor disk (1) faces the curable layer, - Curing of the curable layer, - Removal of the substrate semiconductor disk including curable layer and film from the coating device, • at least the following steps of an initial processing sequence: - Placing the substrate semiconductor disk (1) onto a first placement surface (101.1) of a first placement device (101), wherein the first disk side (1.1) faces the first placement surface (101.1), - Building up an intake pressure in the first storage device (101) via a first intake unit, - Suction of the curable layer, and in particular the substrate semiconductor disk (1), to the first depositing surface (101), - Grinding a second (1.2) side of the substrate semiconductor disk (1) opposite the first (1.1) side of the disk over a first grinding head (103.1) of a first grinding device (103), - Removal of the substrate semiconductor wafer including curable layer and film from the first deposit surface (101.1), - Detachment of the curable layer from the substrate semiconductor disk (1 ), and • at least the following steps of a second processing sequence: - Placing the substrate semiconductor disk (1) onto a second storage surface (102.1) of a second storage device (102), wherein the second disk side (1.2) faces the second storage surface (102.1), - Building up suction pressure in the second storage device (102) via a second suction unit, - Suction of the substrate semiconductor disk (1) to the second deposit surface (102.1), - Grinding the first side of the disc (1.1) over a second grinding head (104.1) of a second grinding device (104), - Removal of the substrate semiconductor disk (1) from the second storage surface, characterized by the fact that - at least one of the first (101.1) and second (102.1) storage surfaces is designed as a curved surface which, viewed along an associated radial axis through the associated storage device (101, 102), defines an associated storage device contour, wherein a projected contour diameter, viewed along the associated radial axis, is assigned to this contour diameter which has a value in the range of 300 mm to 320 mm, and wherein the course of the value of the curvature, viewed at least sectionally, preferably predominantly, and further preferably over the entire storage surface, is in a range of 7.81 x 10' 5 m' 1 up to 5.33x10' 3 m' 1 , preferably in the range of 3.12x10' 4 m' 1 up to 2.67x10' 3 m' 1 , preferably in the range of 5.47x10' 4 m' 1 up to 1.33x10' 3 m' 1 , lies.
2. The method of claim 1, wherein the second processing sequence is immediately preceded by a further coating sequence in which a further curable layer and a further film are applied to the second deposit surface (102.1), resulting in the following steps after completion of the first processing sequence: • at least the following steps in the further coating sequence: - Applying another film to another coating surface of another coating device and then applying another curable layer to it, - Placing the substrate semiconductor disk (1) onto the further curable layer, wherein the first disk side (1.1) of the substrate semiconductor disk (1) is facing the further curable layer, - Curing of the next curable layer, - Removal of the substrate semiconductor disk including further curable layer and further film from the further coating device, and • at least the following steps of the second processing sequence: - Placing the substrate semiconductor disk (1) onto the second deposit surface (102.1) of the second deposit device (102), wherein the second disk side (1.2) faces the second deposit surface (102.1), - Building up an intake pressure in the second storage device (102) via the second intake unit, - Suction of the substrate semiconductor disk (1) to the second deposit surface (102.1), - Grinding of the first disc side (1.1) over the second grinding head (104.1) of the second grinding device (104), - Removal of the substrate semiconductor disk (1) from the second storage surface, - Detachment of the further curable layer from the substrate semiconductor disk (1).
3. Method according to claim 1 or 2, wherein A first storage device (101) is selected whose first storage surface (101.1), viewed along a first radial axis through the first storage device (101), defines a first storage device contour, wherein the course of the value of the curvature within at least one concave and / or within at least one convex curved section in the region of 7.81x10' 5 rrr 1 up to 5.33x10' 3 m' 1 , preferably in the range of 3.12x10' 4 m' 1 up to 2.67x10' 3 m' 1 , preferably in the range of 5.47x10' 4 rrr 1 up to 1.33x10' 3 rrr 1 , lies. 29 4. Method according to any one of claims 1 to 3, wherein - as a second storage device (102) is selected a storage device whose second storage surface (102.1), viewed along a second radial axis through the second storage device (102), defines a second storage device contour, wherein the course of the value of the curvature within at least one concave and / or within at least one convex curved section in the range of 7.81x10' 5 rrr 1 up to 5.33x10' 3 m' 1 , preferably in the range of 3.12x10' 4 m' 1 up to 2.67x10' 3 m' 1 , preferably in the range of 5.47x10' 4 rrr 1 up to 1.33x10' 3 m' 1 , lies.
5. Method according to any one of the preceding claims, wherein - one of the two storage devices is selected with a storage surface (101.1) that is at least partially concave and / or convex, - and the other of the two storage devices is selected with a substantially flat surface.
6. Method according to any one of the preceding claims, wherein For the grinding step during the first and / or second machining sequence, a detachably mountable grinding head (105.1) is selected as part of the associated grinding device (103, 104), which is designed as a flat grinding wheel or cup wheel, wherein During the grinding step, the feed axis of the first and / or second grinding head (105.1) is inclined relative to a rotation axis of the associated storage device via a feed angle, and this feed angle is varied during the grinding step to process the facing side of the substrate semiconductor disk.
7. Substrate semiconductor wafer with a nominal diameter of substantially 300 mm, wherein the substrate semiconductor wafer (1) has a global grinding target geometry with at least one section having a warp value in the range of 1 pm to 60 pm, preferably in a range of 4 pm to 30 pm, more preferably in a range of 7 pm to 15 pm, and 2023P00024WG / HA 30 wherein the nanotopography values on each of the two disk sides, in particular measured and filtered by double Gaussian filtration in a round, local window with a diameter of 25 mm according to SEMI M78-0923 - Guide for determining nanotopography of unpatterned silicon wafers high volume manufacturing - 2010 / 2023, do not exceed a value of 15 nm, preferably 10 nm, at each position of the disk sides of the substrate semiconductor disk.
8. Substrate semiconductor disk according to claim 7, wherein the first disk side is at least sectionally concave and / or at least sectionally convexly curved.
9. Substrate semiconductor disk according to claim 7 or 8, wherein the second disk side is at least partially concave and / or at least partially convex.
10. Method for producing a semiconductor wafer (10) comprising a substrate semiconductor wafer (1) with at least one epitaxial layer (3), wherein - starting from the processing method according to one of the preceding claims 1 to 6, after removal of the substrate semiconductor disk (1) from the processing device after completion of the second processing sequence, the substrate semiconductor disk (1) has a global grinding target geometry with at least one section with a warp value in the range of 1 pm to 60 pm, preferably in a range of 4 pm to 30 pm, more preferably in a range of 7 pm to 15 pm, - following the removal, at least one etching step of the substrate semiconductor disk (1) is performed, - and then at least one polishing step is performed on the first (1.1) and / or the second (1.2) side of the disk on a polishing device, wherein during the at least one polishing step the substrate semiconductor disk (1) on the first (1.1) and / or the second (1.2) side of the disk is selectively polished by the polishing device with a local polishing removal on the substrate semiconductor disk (1) on the relevant side of the disk, 31 - and then in particular a cleaning step of the substrate semiconductor disk (1) takes place, - and then a layer is deposited on at least one disk side (1.1, 1.2) of the substrate semiconductor disk (1), wherein o on one of the two disk sides of the substrate conductor disk (1 ) at least one epitaxial layer (3) is deposited within an epitaxial device, wherein the at least one epitaxial layer (3) comprises in particular GaN and / or silicon, o and in a time prior, in particular on the other side of the substrate semiconductor disk (1) a low thermal oxide layer (2) is applied.
11. Method according to claim 10, wherein the at least one epitaxial layer (3) is locally applied to the substrate semiconductor disk (1) such that a predefinable target thickness of the produced semiconductor disk (10) in the range of 600 pm to 1000 pm is achieved and / or the produced semiconductor disk (10) has a warp value of less than 4 pm.
12. Processing device designed for processing a substrate semiconductor disk (1) according to any one of claims 1 to 6, comprising - at least one grinding head (103.1, 104.1) on an associated at least one grinding device (103, 104) and - at least one coating device with an associated coating surface, - a first storage device (101) with a first storage surface (101.1) and a first intake unit, - a second storage device (102) with a second storage surface (102.1) and a second intake unit, characterized by the fact that, - at least one of the first (101.1) and second (102.1) storage surfaces is designed as a curved surface, wherein, viewed along an associated radial axis through the associated storage device (101, 102), an associated storage device contour is defined, wherein this a 32 projected contour diameter, viewed along the associated radial axis, which has a value in the range of 300 mm to 320 mm, and wherein the course of the value of the curvature, viewed at least sectionally, preferably predominantly, further preferably over the entire storage surface, in a range of 7.81x10' 5 m' 1up to 5.33x10' 3 m' 1 , preferably in the range of 3.12x10' 4 m' 1 up to 2.67x10' 3 m' 1 , preferably in the range of 5.47x10' 4 m' 1 up to 1.33x10' 3 m' 1 , lies.