JP2010212408A - Method for preventing close adhesion among mutual cut sheet, and device for preventing close adhesion used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently supply the surface of each cut sheet with a treatment liquid by providing a method for preventing close adhesions among mutual cut sheets in case of washing and a device for preventing the close adhesions in the method. <P>SOLUTION: In the method for preventing the close adhesions among the mutual cut sheets, an ingot is cut continuously in a laminar shape, a sheet group 4 fixing one end of each cut sheet 8 is used as an object. Bubbles 11 are mixed among the sheets 8 of the sheet group 4 in a process of immersing the sheet group 4 fixing one end of each cut sheet 8 in a treatment liquid tank 2 convecting the treatment liquid 1 and removing impurities from the surface of each cut sheet 8. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an adhesion prevention method between cut thin plates and an adhesion prevention apparatus used in the method.

  Conventionally, silicon ingots used for semiconductor elements and solar cells are cut into thin plates by using a wire saw so that they can be used as product materials (hereinafter referred to as “cut thin plates” in this application) ). Each cut sheet immediately after cutting is held on one side by an adhesive for the convenience of subsequent cleaning treatment, so that it is not separated and separated (hereinafter referred to as the cut sheet in this state). Is referred to as a “thin plate group” in this application).

  One step of washing each cut sheet is called slurry washing, but typical slurry washing involves spray washing each cut sheet with water, and then washing with water, washing with washing liquid, washing with water, and adhesion with stripping solution. It will be washed in the order of agent peeling and water washing.

  In slurry cleaning, each cutting thin plate is contaminated with liquid dirt used at the time of cutting, so the treatment liquid is convected around each cutting thin plate, and the surface of the cutting thin plate is cleaned by the cleaning power and convection effect of the liquid itself. The process of removing dirt is performed. At that time, each cut thin plate is held with an adhesive on one side as described above, but after removing the dirt with the treatment liquid, the adhesive is melted by peeling the adhesive with the peeling liquid, and each cutting The thin plate is broken apart.

  Then, after the slurry cleaning, in order to remove finer dirt, the main cleaning is performed on each cut thin plate one by one.

JP 2008-98439 A (0016, 0017, 0050, 0060) JP 2008-103701 A (0013 stage)

  By the way, there is only about 0.2 mm between the cut thin plates holding one side. For this reason, at the time of the first water washing of the slurry washing, the adjacent cut thin plates are in close contact with each other due to the influence of the surface tension of water and other influences. As a result, in the thin plate group, there are scattered portions where the cut thin plates are in close contact with each other, and the treatment liquid does not spread over the close contact surface, which causes a problem that cleaning is liable to occur. In this way, the portions where the cut thin plates are in close contact with each other are left with a large amount of dirt, resulting in poor cleaning even in the subsequent main cleaning step, and ultimately defective products.

  Further, as a recent trend, from the viewpoint of resource saving, each cut sheet is required to be thinner, and the above problem becomes more serious.

  The present invention was devised in view of the above problems of the prior art, and provides a technique for preventing adhesion between the respective cut thin plates during cleaning, thereby sufficiently supplying the treatment liquid to the surface of each cut thin plate. It is something to try.

  Conventionally, it is known from various documents that various cleaning processing efficiencies can be improved by using bubbles in the substrate processing liquid process (for example, Patent Documents 1 and 2).

  Initially, the present inventors thought that the cleaning processing efficiency could be improved even in the cleaning processing step of a cutting thin plate such as a silicon wafer based on such known knowledge, and the effect was confirmed. Therefore, under the same conditions as the main cleaning, that is, each thin plate obtained by cutting the ingot was put into the treatment liquid, and air bubbles were blown there, and the test was performed. No cleaning effect was obtained.

  On the other hand, when the test was performed with air bubbles mixed under the same conditions as so-called slurry cleaning, that is, in the state of a thin plate group in which one end of each cut thin plate was fixed, this time, the cleaning effect was remarkably improved. did.

  As a result of careful examination of the results of this experiment, the present inventors, in slurry cleaning, did not directly increase the cleaning effect of bubbles, but actively formed gaps between the cut thin plates in the thin plate group. Thought that the cleaning effect was enhanced. In other words, if bubbles enter the gap and give elasticity to assist in forming the gap, the treatment liquid efficiently penetrates into the gap, and the treatment liquid comes into contact with every corner of the thin plate surface. Will increase. Therefore, in order to confirm the inference, when the test described in the example described later was performed, the result of forming the gap between the cut thin plates reliably and evenly was obtained, and the inference of the present inventors can be affirmed As a result.

  Such a novel finding found by the present inventors is the technology itself that can solve the problems in the slurry cleaning as described above, and therefore, the inventors of the present invention based on the novel finding. It came to invent. That is, the method for preventing adhesion between the cut thin plates according to the present invention is a method in which an ingot is continuously cut into a thin plate shape, and a thin plate group in which one end of each cut thin plate is fixed is immersed in a processing liquid tank in which processing liquid is convected. In the step of removing impurities from the surface of each cut thin plate, air bubbles are mixed between the thin plates of the thin plate group to which one end of each cut thin plate is fixed.

  Here, the bubble needs to have a size that can penetrate into the gap between the cut thin plates of the thin plate group. For example, when the thin plate is a silicon wafer of a semiconductor element, the bubble is also an ultrafine microbubble. Or a size called nanobubble, that is, a diameter of about 1 / 1,000,000 mm to 1 / 1,000,000 mm. Moreover, the ingot of the material of each cut thin plate is not limited to a silicon ingot, and other ingots are included.

  The above method can be easily carried out if there is an air bubble generating device and an injection device that injects the generated air bubbles so as to be mixed between the thin plates of the respective cut thin plates of the thin plate group. Therefore, such an apparatus is also proposed as the invention of claim 2.

  According to the present invention, the bubbles in the processing liquid can enter between the adjacent cut thin plates, and the elasticity of the bubbles can prevent the cut thin plates from being adhered to each other. For this reason, the processing liquid completely enters between the respective cut thin plates, thereby preventing a cleaning failure.

  Further, even if each cut thin plate is taken out from the processing liquid, if the bubbles remain attached, the adjacent cut thin plates can be kept separated from each other. Therefore, in the main cleaning process, the processing liquid spreads in the gaps between the respective cut thin plates, and the cleaning accuracy is greatly improved.

It is the schematic of a slurry washing | cleaning apparatus, Comprising: It is a figure which shows the embodiment example to which this invention was applied. It is explanatory drawing of the process liquid tank part of FIG.

  Specific embodiments of the invention according to the present application will be described with reference to the drawings. This embodiment is an example in which the present invention is applied to an apparatus in which slurry cleaning, which is one step for obtaining a semiconductor element or a solar cell base material from a silicon ingot, is performed. It should be noted that the embodiments shown below are merely examples of the present invention, and not only the applied bubble generation device and bubble injection device, but also the specific forms of the injection nozzle, pump, and processing liquid tank are included in these examples. Of course, the invention is not limited.

  FIG. 1 is a schematic view of a slurry cleaning apparatus, in which 1 is a processing liquid, 2 is a processing liquid tank, 3 is a circulation device, 4 is a group of thin plates obtained by cutting a silicon ingot, 5 is a pump, 6 is An injection device, 7 is an injection nozzle, 8 is a cut thin plate, 9 is a fixed adhesive portion, 10 is a bubble generating device, and 11 is a nanobubble.

  As shown in the figure, the slurry cleaning device is obtained by cutting the treatment liquid tank 2 filled with the treatment liquid 1, the circulation device 3 for circulating the treatment liquid 1 in the treatment liquid tank 2 and the silicon ingot. And a supporting device (not shown) for supporting the thin plate group 4 to be movable up and down. The circulation device 3 draws the processing liquid 1 from the bottom of the tank and returns the extracted processing liquid 1 to the tank, and in order to cause convection in the tank when the processing liquid 1 is returned to the tank by the pump 5. And a circulation flow path is formed by a flow path connecting them. The injection device 6 includes an injection nozzle 7 at the tip. The support device is disposed on the upper part of the processing liquid tank 2, and raises and lowers the thin plate group 4 in the processing liquid tank 2 by a moving mechanism. Here, as described in the prior art, the thin plate group 4 is formed by continuously cutting a silicon ingot with a wire saw to form a cut thin plate 8, and each of the cut thin plates 8 has one upper end at each fixed adhesive portion 9. It is formed by being held in the.

  In this embodiment, in such a slurry cleaning apparatus, the bubble generation device 10 is disposed in the flow path between the pump 5 and the injection device 6, and the injection nozzle 7 of the injection device 6 is described later. The thin plate group 4 is set so as to face between the thin plates.

  The bubble generating device 10 of the present embodiment is a device for generating ultrafine so-called nanobubbles 11. First, a gas is sucked using the negative pressure of the pump 5, and a gas-liquid consisting of a gas and a circulating processing liquid is used. A mixture is prepared, and the gas-liquid mixture is stirred and mixed in a mixer provided therein to generate nanobubbles 11. Such nanobubbles 11 flow in the circulation flow path in the same manner as the other processing liquids 1 and are jetted in the processing liquid tank 2 by the jetting device 6. In this embodiment, since the nozzle 7 of the injection device 6 is set so as to face between the thin plates of the thin plate group 4 (in FIG. 2, the arrow is the injection direction), the nanobubbles generated in the bubble generation device 10 11 goes to the space between the thin plates together with the processing liquid 1 and is actively mixed in the gap.

  In the present embodiment configured as described above, the support device is lowered to lower the thin plate group 4 in which the upper ends of the respective cut thin plates 8 are fixed to a position in the processing liquid layer 2 where the injection nozzle 7 is installed. The thin plate group 4 receives the treatment liquid 1 ejected from the ejection nozzle 7 while being immersed in the filled treatment liquid 1. In the jetting treatment liquid 1, nanobubbles 11 are mixed and mixed into the gaps between the cut thin plates of the thin plate group 4. As a result, the cut thin plates are prevented from closely contacting each other, and an elastic and uniform gap is formed, so that the treatment liquid 1 penetrates into every corner and contacts the surface of each cut thin plate 8, and from the surface. Impurities will be removed.

  In the above embodiment, the treatment liquid and the nanobubble injection device are common, but it is natural that separate injection devices may be used. Including that point, it goes without saying that the present invention is not limited to the above-described embodiments, and if the bubbles are used in a method for preventing adhesion between cut thin plates, the function of the bubble generating device or bubble jetting device is used. The size, shape, etc. of the injection nozzle, pump, and treatment liquid layer can be changed as appropriate, and these are of course included in the scope of the present invention.

  A test for confirming a gap forming effect by nanobubbles, which is a basic knowledge of the present invention, was conducted. In the bubble generating apparatus of the above embodiment, when nano bubbles are generated and sprayed together with the processing liquid from the spray nozzle (test example of the present invention), only the processing liquid is sprayed from the spray nozzle without generating nano bubbles. In each case (comparative example), the gap state between the cut thin plates of the thin plate group was confirmed. According to the results, in the test example of the present invention, there is a clean gap between the cut thin plates, whereas in the comparative example, the cut thin plates are in close contact with each other. ing. From these experimental results, it was clearly confirmed that the use of nanobubbles had fewer portions where the cut thin plates were in close contact with each other, and gaps were evenly formed.

  The present invention is a technique that can be used in a substrate processing liquid process.

1 Treatment liquid
2 Treatment tank
4 Thin plate group obtained by cutting silicon ingot
6 Injection device
7 Injection nozzle
8 Cutting sheet
10 Bubble generator
11 Nano bubbles

Claims (2)

A group of thin plates in which ingots are continuously cut into thin plates and one end of each cut thin plate is fixed,
In the process of removing impurities from the surface of each cut thin plate by immersing in a treatment liquid tank in which the treatment liquid convects,
A method for preventing adhesion between cut thin plates, wherein bubbles are mixed between the thin plates of the thin plate group to which one end of each cut thin plate is fixed. A bubble generating device;
An injection device for injecting the generated bubbles so as to be mixed between the respective cut thin plates;
The adhesion prevention apparatus used for the adhesion prevention method between the cut thin plates of Claim 1 characterized by these.

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