Method for manufacturing silicon wafers from silicon ingot wings
By cutting and bonding silicon ingot wings to form high-quality wafers, the method addresses the inefficiency of recycling ingot wings, achieving cost-effective and high-performance solar panel production.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- RELIANCE IND LTD
- Filing Date
- 2025-12-02
- Publication Date
- 2026-06-11
AI Technical Summary
Conventional methods waste significant amounts of prime-quality silicon ingot wings during wafer production, as they are recycled inefficiently, requiring energy-intensive processes.
A method involving cutting rectangular silicon blocks from ingot wings, bonding them with a material like high-temperature epoxy or glass, and then cutting these blocks perpendicularly to form high-quality silicon wafers, reducing energy consumption and utilizing the wings effectively.
This method efficiently transforms silicon ingot wings into high-quality wafers, reducing energy costs and enabling the production of shingled solar panels with improved performance by minimizing heat-affected zones.
Smart Images
Figure IN2025051982_11062026_PF_FP_ABST
Abstract
Description
[0001] “METHOD FOR MANUFACTURING SIEICON WAFERS FROM SILICON INGOT WINGS”
[0002] TECHNICAL FIELD
[0003] The present disclosure relates to the field of manufacturing. Particularly but not exclusively, the present invention relates to a method for manufacturing silicon wafers from silicon ingot wings.
[0004] BACKGROUND
[0005] A solar cell or photovoltaic cell is an electronic device that converts solar energy into electricity by means of photovoltaic effect. In general, photovoltaic cells use amorphous silicon, polycrystalline and monocrystalline silicon wafers based on field of application.
[0006] Monocrystalline silicon (Si) wafer based solar cells remains one of the crucial technologies in renewable energy. A conventional process for manufacturing monocrystalline silicon is Czochralski (Cz) process. Generally, silicon ingots grown from the Cz process are inspected for their electrical and material properties. A section of the ingot qualifying the electrical and material requirements is called usable / qualified / prime material. The prime material is obtained by removing a crown, tail and body sections which do not meet the requirements. The qualified section of ingot is sliced into smaller pieces (e.g. 850-950mm) for further processing. However, length of these ingot pieces can be <200mm to >1000 mm, depending on ingot length and processing capabilities of the equipment. As an example, in order to process a cylindrical ingot piece, the cylindrical ingot piece is fed into a squarer and chamfering machine to cut it into rectangular parallelepiped brick with full square or pseudo-square cross section as per the requirements of final wafer dimensions. Apart from the cut and processed silicon brick, four convex-flat sections termed as wings are also produced from periphery of the cylindrical ingot during squaring.
[0007] In existing process of producing silicon wafers from Cz-Si ingots, about 30-36% of the prime quality Cz-Si material is produced in the form of wings (particularly about 36% in production of square wafers from cylindrical Cz-Si ingots such as commercial G12 full square / G12 half - cut wafers). The leftover material (wings) is not utilized properly and is generally recycled and used with fresh polysilicon for crystal growth. However, the wings of the silicon ingot are prime material and exhibit similar properties to squared or half cut silicon bricks. Recycling the wings back again into the Cz process is energy intensive and expensive.
[0008] The present disclosure is directed to overcome one or more limitations stated above or any other limitation associated with the conventional arts.
[0009] The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
[0010] SUMMARY OF THE DISCLOSURE
[0011] One or more shortcomings of the conventional methods are overcome by the method disclosed in present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.
[0012] In a non-limiting embodiment of the present disclosure, a method for manufacturing silicon wafers from silicon ingot wings is disclosed. The method includes cutting, by a wire saw machine, a plurality of rectangular silicon blocks from silicon ingot wings. Further, the method includes bonding the plurality of rectangular silicon blocks along at least one of a width or a thickness of each of the plurality of rectangular silicon blocks to obtain a joined silicon blocks. Furthermore, the method includes cutting, by a wire saw machine, the joined silicon blocks along a cutting plane substantially perpendicular to a length of the joined rectangular silicon blocks to obtain a plurality of silicon wafers.
[0013] In an embodiment of the present disclosure, the bonding includes coating a bonding material on a major surface of each of the plurality of rectangular silicon blocks, wherein the major surface is a surface defined by at least of a length and width, or length and thickness of the plurality of rectangular silicon blocks.
[0014] In an embodiment of the present disclosure, the joined silicon blocks being cut at an angle of about 90°± 10° with respect to a length of the joined silicon blocks. In an embodiment of the present disclosure, the bonding material is at least one of high temperature epoxy glues, glass, ceramics, glass-ceramics, dielectrics, high purity semiconductors and polymers.
[0015] In an embodiment of the present disclosure, a thickness of the coating of the bonding material ranges between 0.001 mm to 5.0 mm.
[0016] In an embodiment of the present disclosure, the method includes at least one of drying, heating, application of pressure upon coating of the biding agent.
[0017] In an embodiment of the present disclosure, the methods includes shaping and grinding the joined silicon blocks to obtain a defect free surface of the joined silicon blocks.
[0018] In an embodiment of the present disclosure, the wire saw machine is a loop wire saw machine to cut the plurality of rectangular silicon blocks and a multi-diamond wire saw machine to cut the plurality of joined silicon blocks.
[0019] In an embodiment of the present disclosure, a shingled PV panel manufactured using the plurality of silicon wafers obtained by the method of the present disclosure.
[0020] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.
[0021] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
[0022] BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[0023] The novel features and characteristics of the disclosure are set forth in the appended description. The disclosure itself, however, as well as a preferred mode of use, further objectives, and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which: Fig- 1 is a flowchart describing a process for preparing silicon wafers from wings, in accordance with an embodiment of the present disclosure.
[0024] Fig- 2 is a schematic view of rectangular blocks cut from the wings, in accordance with an embodiment of the present disclosure.
[0025] Fig- 3 is a schematic view of process of joining the rectangular blocks obtained from wings, in accordance with an embodiment of the present disclosure.
[0026] Fig. 4 is a magnified view of the joining interface between the joined silicon blockss, in accordance with an embodiment of the present disclosure.
[0027] Fig. 5 is a schematic view of wafering of joined brick cutting done along thickness of wings, in accordance with an embodiment of the present disclosure.
[0028] Fig. 6 is a schematic view of wafering of joined brick cutting done along width of wings, in accordance with an embodiment of the present disclosure.
[0029] Fig. 7 is a sectional view of shingled solar panel, in accordance with an embodiment of the present disclosure.
[0030] The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the apparatus and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
[0031] DETAILED DESCRIPTION
[0032] The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent processes do not depart from the scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure.
[0033] The terms “comprises”, “comprising”, or any other variations thereof used in the specification, are intended to cover a non-exclusive inclusion, such that the system comprises a list of features / elements or steps does not include only those features / elements, but may include other features and elements not expressly listed or inherent to such setup or structure. In other words, one or more features / elements in a system proceeded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system thereof. Also, the terms like “at least one” and “one or more” may be used interchangeably or in combination throughout the description.
[0034] Embodiments of the present disclosure relate to a method for manufacturing silicon wafers from silicon ingot wings. The method includes cutting, by a wire saw machine, a plurality of rectangular silicon blocks from silicon ingot wings. Further, the method includes bonding, the plurality of rectangular silicon blocks along at least one of a width or a thickness of each of the plurality of rectangular silicon blocks to obtain one or more stacks of rectangular silicon blocks. Furthermore, the method includes cutting, by a wire saw machine, the one or more stacks of rectangular silicon blocks along a cutting plane substantially perpendicular to a length of the one or more stacks of rectangular silicon blocks to obtain silicon wafer of predefined dimensions. Reference will now be made to the exemplary embodiments of the disclosure, as illustrated in the accompanying drawings. Wherever possible, the same numerals will be used to refer to the same or like parts. Embodiments of the disclosure are described in the following paragraphs with reference to Fig. 1 to Fig. 7. In Fig. 1 to Fig. 7, the same element or elements which have same functions are indicated by the same reference signs.
[0035] Referring now to Fig. 1 which is an embodiment of the present disclosure illustrating a flow chart of a method (200) for describing a process for preparing silicon wafers from wings (20).
[0036] The order in which the method (200) is described is not intended to be construed as a limitation, and any number of the described method (200) blocks may be combined in any order to implement the method (200). Additionally, individual blocks may be deleted and added from the method (200) without departing from the scope of the subject matter described herein.
[0037] Referring to Fig. 2, which illustrates sequence of operation of obtaining a rectangular silicon blocks (30) from a silicon ingot (100). Here, the Silicon ingot (100) may be obtained from a Czochralski process (Cz-process). The silicon ingot (100) may be defined with a geometric cross section such as but not limited to square, rectangle, circle, triangle etc. In the foregoing disclosure, reference may be made to silicon ingots having a circular cross section or a cylindrical shape, however, the same should not be construed as a limitation but rather an example for easy understanding. Further, the cylindrical silicon ingot (10) [best seen in Fig. 2] may be termed as qualified ingot or pure silicon ingot (100). The cylindrical silicon ingot (10) may be passed through a squarer to remove a central portion (15) of the cylindrical silicon ingot (10). The central portion (15) of the silicon ingot (100) may be defining a square or a pseudo-square cross section. In a Czochralski process, a plane parallel to the square or pseudo-square cross section may be {100} plane. The {100} plane may be a plane with low resistivity variation and least variation of MLCT (minority carrier lifetime). Further, the central portion (15) may be defining a length ranging between 200 mm to 1000 mm. However, the length of the central portion (15) should not be construed as a limitation as the same is used as an example and not a structural limitation for implementation of the method (200). In consequence of the squaring operation, four curved blade like structures but not limited to its shape (i.e. convex-flat cross section), size, or length may be obtained [best seen in Fig. 2], Such structures may be termed as wings (20) [also termed as silicon wing]. The silicon wing (20) may be obtained from the silicon ingot (100) and defined with a length equivalent to the length of the central portion (15).
[0038] At block 101, the method (200) includes cutting a plurality of rectangular silicon blocks (30) from the plurality of wings (20). Here a wire saw machine may be used to cut the plurality of rectangular silicon block. The wire saw machine may correspond to a loop wire saw machine having a thick wire coated with diamond for cutting the plurality of rectangular blocks. The rectangular silicon blocks (30) [best seen in Fig. 3] cut from the plurality of wings (20) may be defined with a thickness (t), a width (w) and a length (1). The length (1) of the rectangular silicon blocks (30) cut from the wings (20) may be equivalent to the length of the central portion (15) of the qualified silicon ingot (10).
[0039] At block 102, the method (200) includes bonding the plurality of rectangular silicon blocks (30) [as seen in Fig. 3 ] to join the plurality of rectangular silicon blocks (30) one over other to obtain a joined silicon blocks (40). Here, bonding includes coating a bonding material (31) on a major surface of each of the plurality of rectangular silicon blocks (30). The major surface is a surface defined by at least of a length and width, or length and thickness of the plurality of rectangular silicon blocks (30). Here, the plurality of rectangular silicon blocks (30) may be arranged along at least one of the width (w) or the thickness (t) of the plurality of rectangular silicon blocks (30) such that total dimensions of the joined silicon blocks (40) may be equivalent to at least one of predefined length (L), predefined width (W) or predefined thickness (T). For example, as seen in Fig. 4, eight rectangular silicon blocks (30) of dimensions (1 xw xt = 950 mm x l07 mm x26.5 mm), obtained from wings (20) of standard 12-inch Cz-Si ingot for G-12 full square wafer production, may bejoined parallel to its width forming the joined silicon blockss (40) of predefined dimensions (1 xw xT = 950 mm x l07 mm x212 mm) to produce G12 half-cut wafers (105 mm x210 mm). The rectangular silicon blocks (30) may be joined parallel to width (w) or thickness (t) or a combination of width and thickness depending on final wafer dimensions as per requirements. The rectangular silicon blocks (30) may be joined in the same orientation with similar MCLT / resistivity range. Further, the bonding process may include coating a bonding material (31) to at least one face of the rectangular silicon blocks (30). In an embodiment, the bonding material (31) may be materials such as but not limited to high temperature epoxy-glues, glass, ceramics e.g. silica (SiOx), glass-ceramics, dielectrics, high purity semiconductors e.g. Si, organics such as polymers BCBs, etc.. The bonding material (31) may be applied in the form of dry powder, molten form, frit, water based slurry or non-water-based slurry, two or multicomponent solutions, etc. The particle size of the bonding material (31) may be of micron, submicron, or nano-size as per feasibility of coating techniques used. Furthermore, the bonding process may include stacking a plurality of rectangular silicon blocks (30) one over the other such that the joined silicon blocks (40) sandwich the bonding material (31). Such sandwiched portion may be termed as a bonding interface (41). In an embodiment, thickness of the bonding interface (41) of the bonding material (31) may range between 0.001 mm to 5.0 mm. Furthermore, the bonding process may include drying, heating, and application of pressure / force and / or specific ambient such as vacuum, N2, Ar, etc. to impart required force to join the plurality of rectangular silicon blocks (30). In this bonding process, the type, form, and composition of bonding material (31), process conditions and its application method (200) used should not be construed as a limitation but rather an example without departing from the scope of the present disclosure. In an embodiment, stacking of rectangular silicon blocks (30) may be performed by providing an additional margin of 2 mm in at least one of the predefined width (W) and predefined thickness (T) of the joined silicon blockss (40). Such a margin may be provided for grinding and surface finishing step [As indicated in block 104] required before the wafering process.
[0040] At block 104, the joined silicon blocks (40) may be subjected to shaping and grinding operations followed by surface finishing to obtain a defect free and smooth surface.
[0041] At block 103, the joined silicon blocks (40) may be cut along at least one of width [best seen in Fig. 5] or thickness [best seen in Fig. 6] of rectangular silicon blocks (30) perpendicular to the length (1) of the rectangular silicon blocks (30) to obtain a plurality of joined silicon wafers (60) of required dimensions. The silicon wafers thus produced contain a predefined number of bonding interface (41). In an embodiment, a wire saw machine such as multi-diamond wire saw machine may be used for cutting the joined silicon blocks (40). The cutting of the joined silicon blocks (40) may be along a cutting plane at 90°± 10° with respect to the length (1) of the rectangular silicon blocks (30). Cutting of the joined silicon blocks (40) in the cutting plane substantially perpendicular to the length (1) of the rectangular silicon blocks (30) assists in exposing a surface of the silicon wafers possessing {100} plane. Such planes in silicon wafers may be defining reduced variation of resistivity of individual silicon wafer as well as lower variation in MCLT of the silicon wafer. Such effect may be achieved by cutting the joined silicon blocks (40) in the cutting plane perpendicular to the length i.e., parallel to {100} plane. Thus, the obtained plurality of joined silicon wafers (60) may be inspected for geometric inconsistencies and further processed into solar cells.
[0042] In an operational embodiment, the wings (20) obtained from the squaring process of the silicon ingot (100) may be subjected to cutting operation to obtain rectangular silicon blocks (30) of predefined dimensions. In another embodiment, the rectangular silicon blocks (30) may be cut from the wings (20) such that a largest possible rectangular silicon blocks (30) may be cut from the wings (20). The plurality of rectangular silicon blocks (30) obtained from the wings (20) may be joined together by stacking along any one of the width (w) or the thickness (t) of the rectangular silicon blocks (30) and applying a bonding material (31) between them. Further, the joined silicon blocks (40) may be subjected to shaping, grinding and polishing for defect free and smooth joined silicon blocks (40) with required dimensions. Furthermore, the joined silicon blocks (40) may be cut in a direction perpendicular to the length of the joined silicon blocks (40) to expose a {100} plane of the rectangular silicon blocks (30) and obtain joined silicon wafers (60) of required dimension with {100} surface orientation.
[0043] The method (200) of the present disclosure may assist in reducing energy spent to recycle silicon wings (20) by reusing the portions of the wings (20) to obtain joined silicon wafers (60) for processing to solar cells. Further, the joined silicon wafers (60) may be processed and used as solar cell. Manufacturing of shingled solar PV panels may be a prospective application of joined silicon wafers (60) produced in this method (200). Unlike conventional methods, in the present disclosure heat affected zones formed during laser cutting and causing edge recombination may not be occur during formation of shingled solar panels (70) [as seen in Fig. 7],
[0044] The silicon wafers obtained through the method (200) of the present disclosure advantageously includes a bonding interface (41), which can be cut using laser cutting to obtain defect free edge of the processed silicon wafer thereby overcoming need to post process (i.e. edge passivation) of processed silicon wafers (71) to form shingled solar panels (70). Accordingly, during assembly of the shingled solar panels (70), the processed silicon wafers (71) maybe be assembled [best seen in Fig. 7] in a form of a ‘tiled roof’ configuration with electrical contacts (72) and electrically conductive adhesive (73).
[0045] Equivalents:
[0046] With respect to the use of substantially any plural and / or singular terms herein, those having skill in the art can translate from the plural to the singular and / or from the singular to the plural as is appropriate to the context and / or application. The various singular / plural permutations may be expressly set forth herein for sake of clarity. While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purpose of illustration and are not intended to be limiting.
[0047] Referral numerals:
Claims
We claim:
1. A method (200) for manufacturing silicon wafers from silicon ingot wings (20), the method (200) comprising: cutting, by a wire saw machine, a plurality of rectangular silicon blocks (30) from silicon ingot wings (20); bonding the plurality of rectangular silicon blocks (30) along at least one of a width or a thickness of each of the plurality of rectangular silicon blocks (30) to obtain a plurality of joined silicon blocks (40); and cutting, by a wire saw machine, the plurality of joined silicon blocks (40) along a cutting plane substantially perpendicular to a length of the plurality of joined silicon blocks (40) to obtain a plurality of joined silicon wafers.
2. The method (200) as claimed in claim 1 , wherein the bonding includes coating a bonding material on a major surface of each of the plurality of rectangular silicon blocks (30), wherein the major surface is a surface defined by at least of the length and width, or the length and the thickness of the plurality of rectangular silicon blocks (30).
3. The method (200) as claimed in claim 1, wherein the plurality of joined silicon blocks (40) being cut at an angle of about 90°± 10° with respect to the length (1) of the joined silicon blocks (40).
4. The method (200) as claimed in claim 2, wherein the bonding material is at least one of high temperature epoxy glues, glass, ceramics, glass-ceramics, dielectrics, high purity semiconductors and polymers.
5. The method (200) as clamed in claim 2, wherein thickness of the coating of the bonding material ranges between 0.001 mm to 5.0 mm.
6. The method (200) as claimed in claim 2 comprises at least one of drying, heating, application of pressure upon coating of the bonding material.
7. The method (200) as claimed in claim 1 comprising shaping the joined silicon blocks (40) to obtain a defect free surface of the plurality of joined silicon blocks (40).
8. The method (200) as claimed in claim 1, wherein the wire saw machine is a loop wire saw machine to cut the plurality of rectangular silicon blocks (30) and a multi-diamond wire saw machine to cut the plurality of joined silicon blocks (40).
9. A shingled PV panel manufactured using the plurality of joined silicon wafers obtained by the method (200) as claimed in claim 1.