Claims:WE CLAIM
1. A device for drying a semiconductor wafer comprising:
a dryer body (1);
a centrifugal power assembly(2);
an air knife(3);
a lockable wafer carrier placing fixture (4)
a central air knife(5);
a drying (perforated) drum(6);
a drying chamber (7)
a sensor(8);
a temperature controller (9);
a centrifugal baskets (10);
a drive motor;
a drive shaft;
wherein the interior of the dryer body (1) is provided with perforated drying drum (6) and the bottom of the drying drum (6) is extended via rotatable shaft connected with spin drive motor through belt and pulley mechanism.
2. The device as claimed in claim 1, wherein The inner bottom end of the drying drum is surrounded by a lockable wafer carrier placing fixture (4).
3. The device as claimed in claim 1, wherein the top end of the dryer body spin motor is movably provided with transparent acrylic top cover, and the bottom end of the body is arranged around.
4. The device as claimed in claim 1, wherein the dryer is equipped with air blower in conjugation with particulate filters along with heater to provide hot air inside drying chamber (6) via two different air knives(3 &5).
5. The device as claimed in claim 3, wherein one end of the total transfer pipe is connected with air pipe routed through heater, and the other end of the air pipe is connected with an air blower.
6. The device as claimed in claim 1, wherein the bottom of one end of the dryer body is provided with a drain outlet.
7. The device as claimed in claim 1, wherein the drying silicon wafer is done in centrifugal dryer by configuring two separate air knives (3 & 5) oriented inward and outward direction.
, Description:DEVELOPMENT OF CENTRIFUGAL DRYER FOR DRYING SILICON WAFER AFTER TEXURISATION

FIELD OF THE INVENTION:
[001] This invention relates generally to a method of drying a semiconductor wafer. More particularly the invention relates to a method for removing water, from the semiconductor wafer.

BACKGROUND/PRIOR ART OF THE INVENTION:

[002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[003] Silicon is a gray, brittle, tetravalent, chemical element. It makes up 27.8% of the earth’s crust and next to oxygen, it is the most abundant element in nature. In photovoltaic industry, current market share of silicon is more than 90%. Silicon wafer are cut from ingot. In order to increase efficiency, of solar cell, several light trapping techniques are applied in industry, one of such method is texturisation.

[004] In large scale solar cell manufacturing lines, after texturisation of silicon wafers by known chemicals, wafers are dipped in DI water to wash off the chemicals from the surface of the wafers. Further, to dry the wafers, it is treated with IPA solution. Because the IPA has a lower surface tension than water, it introduces a surface tension gradient where it interfaces with the water on the wafer surface. As a result of the Marangoni drying effect, water flows off the surface of the silicon wafer and leaves it dry and clean. Further, PTFE carrier containing silicon wafer is heated in oven to evaporate IPA liquid. The current industrial practice consume lot of hazardous chemical, a source of environment pollution. Further, a dedicated treatment plant is required to process chemical waste. The wafer carrier, made up of PTFE gets deformed over long use in heated oven.

[005] The conventional dryer generally has a poor drying effect, and some of the silicon wafers are wetly bonded together after the operation is completed. If these silicon wafers are not completely dried, they will leave water marks on the surface of the silicon wafer, which will affect the surface quality and consistency of the surface of the wafer. The surface quality of the cleaned silicon wafer is unqualified and discarded. Many attempt have been made to improve the process, few of them are mentioned below.

[006] In a prior art, JPS5687442A, titled “Centrifugal dryer” relates to a centrifugal dryer that dries a liquid to avoid breakage of wafer at high speed, air is fed through a nozzle, from center.

[007] In another prior art, CN209371638U, titled “A kind of new type solar energy silicon wafer drying machine” a utility model provides a kind of new type solar energy silicon wafer drying machine. A brush is introduced in the utility model to enhance cleaning of wafer followed by purge of heated air.

[008] Another prior art, CN202149675U, titled “Drier for solar wafers” discloses a solar wafer dryer, comprising a casing and an upper cover, the casing has a cavity, and a turntable, a turntable and a cavity inner wall are arranged at the bottom of the cavity. The upper cover is movably connected with the casing, the upper cover can cover the mouth of the cavity, and the inner pipe facing the cavity is provided on the inner surface of the upper cover. This dryer uses only centrifugal force to dry Si wafer. The platform is rotated at high speed due to which vibration are being generated which may in turn break the Si wafer.

[009] In conventional dryer water droplet gets trapped at joining position of wafer and carrier. These droplets are tough to be dried as any amount of air is unable to reach it.

[0010] To solve these problem, some industries are using Centrifugal dryer, the conventional dryer is either top loaded or front loaded, the wafer is held on a platform by suitable method and whole assembly is rotated at high speed by an electric induction motor. The centrifugal force exert pressure on water/ chemical droplet radially and subsequently dried.

[0011] In view of the above, there is requirement to devise an apparatus which can address the aforesaid shortcoming(s). Hence, the present invention has been introduced to overcome this problem.

[0012] 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.

OBJECTS OF THE INVENTION:
[0013] It is therefore the object of the present subject matter to overcome the aforementioned and other drawbacks in prior method/product/apparatus.

[0014] The present invention is based on the object of providing a centrifugal dryer for drying both multicrystalline and monocrystalline silicon wafer after texturisation.

[0015] Said object is achieved according to the invention by the features of claim 1. Further, particularly advantageous embodiments of the invention are disclosed in the sub-claims.

[0016] Another object of the present invention is to improve production lines and increase its throughout.

[0017] These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.

SUMMARY OF THE INVENTION:

[0018] One or more drawbacks of conventional systems and process are overcome, and additional advantages are provided through the apparatus/composition and a method as claimed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be part of the claimed disclosure.
[0019] As a green energy source, emphasis on solar energy is increasingly day by day. Silicon wafers are key and basic components in the solar industry. Silicon wafers need to undergo multiple processing steps and layer deposition in during course of production to ensure the photoelectric conversion effect and light utilization efficiency of the silicon wafer. For reducing the reflectance of Si wafers, the surface of the silicon wafer is etched by using an alkali solution for monocrystalline wafers and acidic solution in case of multicrystalline wafers. The area of the etched silicon wafer needs to be immersed in the water tank, the chemical tank, and the water tank in turn. After the silicon wafer is finished, the surface of the silicon wafer needs to be dried to perform the next process on the silicon wafer. For drying various technique such as heating, treatment with IPA, spinning in centrifugal dryer is used.

[0020] The present invention is an improvement to existing centrifugal dryer wherein, air is introduced in drying chamber from two different direction to effectively dry Si wafer.

[0021] The present invention is achieved by the features of principal claim and subsequent claims.

[0022] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

[0023] 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 to form a further embodiment of the disclosure.

[0024] 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.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:

[0025] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods or structure in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:

[0026] Figure 1 illustrates the isometric view of the centrifugal dryer.

[0027] Figure 2 illustrates the cross section view of the Central Air Knives.

[0028] Figure 3 illustrates the closer view of the Loading station.

[0029] Figure 4 illustrates the front view of the dual drum centrifugal dryer.

[0030] Figure 4 illustrates the process of loading PTFE carriers filled with solar cell wafers prior to drying.

[0031] 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 structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S) OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS:

[0032] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.

[0033] The present invention makes a disclosure regarding a technology pertinent to drying a semiconductor wafer, and more particularly, to a method for removing water, from the semiconductor wafer.

[0034] The Present invention relates to the drying both multicrystalline and monocrystalline Si wafer.

[0035] Now reference may be made to Figure-1 illustrating the centrifugal drying assembly comprises two loading stations (1) and a PLC (2).

[0036] Now referring to Figure-2 and 3 illustrating the Central air knife and Loading station arrangement. The Loading station arrangement comprises perforated drying assembly (6), a rotating platform (7), lockable wafer carrier jig (4) a centrifugal power assembly (2), air knife (3) and central air knife (5) are provided for purging air inside drying assembly.

[0037] Now referring to Figure-4 and 5 illustrating the front view of the dual drum centrifugal dryer and process of loading PTFE carriers filled with solar cell wafers prior to drying. The dual drum centrifugal dryer comprises two loading stations (1), two air knives (3 & 5), a sensor (8) mounted on top of brim to acknowledge Lid ON/OFF position, lockable wafer carrier jig (4), temperature controller (9) and two centrifugal baskets (10) of loading station (1). The centrifugal basket (10) of loading station (1) is top loading in nature and is of a "+" shape.

[0038] This equipment has two Loading stations (1), each designed to hold 4 nos. of PTFE wafer carriers (11) (25 wafers per carrier). Thus a maximum of 100 wafers per station can be dried at a time. The wafer carriers (11) are lockable for secure and safe operation. In addition, one blower per station and a fin heater (4.5 kW) is provided in the system. The air is heated with fin heater up to 100 degrees Celsius. The temperature is regulated through temp controller. Air volume flowing in heater is regulated through adjustable valve. One single phase induction motor having linear acceleration, with no jerks, is provided per station, to rotate the carrier platform in both directions. The speed and direction of dryer is controlled through PLC (2).

[0039] The interior of the dryer body of the centrifugal wafer dryer is provided with the perforated drying drum (6). Outer casing of centrifugal wafer dryer is made up of noncorrosive material. The bottom of the dryer body (1) is provided with a spin drive motor. The bottom of the drying drum (6) is extended via rotatable shaft connected with spin drive motor through belt and pulley mechanism. The top end of the driving shaft is fixed to the bottom end of the drying drum (6). The inner bottom end of the drying drum is surrounded by a lockable wafer carrier placing fixture (4). The top end of the dryer body spin motor is movably provided with transparent acrylic top cover, and the bottom end of the body is arranged around.

[0040] The two air knives (3 & 5) are placed at two different position, one (3) lowered from center of closing lid and other (5) from side wall of drying assembly (6) oriented towards center. A blower (not shown in drawings) is provided at the bottom of the dryer in conjugation with particulate filters along with heater to provide hot air inside drying chamber via two different air knives (3 & 5). The blower sucks in ambient air with suitable filters to provided dust free air and forces it through the heaters fins. The air gets heated to preselected temperature and then released in the drying chamber via two different ducts through air knives. One end of the total transfer pipe is connected with air pipe routed through heater, and the other end of the air pipe is connected with an air blower.

[0041] One duct releases the air radially from the centre and the other radially from the side. This ensures that the water droplet on the wafer surface is alternately pushed radially towards and away from the centre. This motion of hot air aids in the drying process and leads to rapid drying. To make the drying more effective, the entire carrier assembly rotates in both directions which ensures that any two adjoining wafers do not stick to one another and thereby result in complete drying of the wafers.

[0042] The advantage of present Invention is that it can be used to dry both multicrystalline and monocrystalline silicon wafers.

[0043] Another advantage of present Invention is that it can be used in production lines.

[0044] The material above has been given as an example without restricting scope of the invention to the same. Thus, other materials readily apparent to a person skilled in the art are within scope of the invention.

[0045] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.

[0046] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.

[0047] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particulars claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogues to “at least one of A, B and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B”.

[0048] The above description does not provide specific details of manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.

[0049] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.

[0050] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.

[0051] 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 purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.