METHOD OF FRAGMENTING OR METHOD OF GENERATING CRACKS IN SEMICONDUCTOR MATERIAL, AND METHOD OF MANUFACTURING SEMICONDUCTOR MATERIAL LUMPS

Abstract

Provided are a method of fragmenting or a method of generating cracks in a semiconductor material, and a method of producing semiconductor material lumps, which can prevent contamination from an electrode material accompanied by application of a high-voltage pulse; in a method of fragmenting or generating cracks in the semiconductor material by applying high-voltage pulse to the semiconductor material disposed in liquid, new fluid is supplied towards at least one of a part on which the high-voltage pulse is applied and a vicinity of an electrode part, and the new fluid and a part of the liquid are drawn from the liquid and discharged.

Claims

1. A method of fragmenting or a method of generating cracks in semiconductor material wherein in a method of fragmenting the semiconductor material or a method of generating cracks in the semiconductor material by applying a high-voltage pulse on the semiconductor material disposed in liquid, a new fluid is continuously supplied to at least one of a part to which the high-voltage pulse is applied in the semiconductor material and the electrode parts.

2. The method of fragmenting or the method of generating cracks in semiconductor material according to claim 1, wherein the new fluid is continuously supplied and the new fluid and a part of the liquid is drawn and discharged from the liquid.

3. The method of fragmenting or the method of generating cracks in semiconductor material according to claim 1, wherein the new fluid is also supplied to semiconductor material after the high-voltage pulse is applied.

4. The method of fragmenting or the method of generating cracks in semiconductor material according to claim 1, wherein at least a part of the new fluid is flowed in a direction different from a direction toward the semiconductor material in an imaginary line in which a distance between a tip end of the electrode parts and the semiconductor material is minimum.

5. The method of fragmenting or the method of generating cracks in semiconductor material according to claim 1, wherein after the new fluid is supplied to a part to which the high-voltage pulse is applied or the electrode parts or the semiconductor material after the high-voltage pulse is applied, at least a part of the new fluid is discharged along with liquid from a system.

6. The method of fragmenting or the method of generating cracks in semiconductor material according to claim 1, wherein the liquid and the fluid are water or pure water.

7. The method of fragmenting or the method of generating cracks in semiconductor material according to claim 1, wherein the liquid and the fluid include bubbles.

8. The method of fragmenting or the method of generating cracks in semiconductor material according to claim 1, wherein the semiconductor material is polycrystalline silicon to be raw material for producing monocrystalline silicon.

9. A method of manufacturing semiconductor material lumps comprising: a forming step of a rod-shape material forming semiconductor material into a rod; and a fragmenting step fragmenting the semiconductor material by the fragmenting method of the semiconductor material according to claim 1 or fragmenting the semiconductor material by a mechanical method after cracks are generated, into semiconductor material lumps.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0036] FIG. 1 is a function drawing of a fragmenting method of semiconductor material.

DESCRIPTION OF EMBODIMENTS

[0037] An embodiment according to the present invention will be explained with referring a drawing.

[0038] FIG. 1 is a function drawing of a fragmenting method or a method of generating cracks of semiconductor material.

[0039] In the fragmenting method or the generating cracks of semiconductor material according to the present embodiment, a silicon rod (semiconductor material) 1 is disposed in liquid. In the present embodiment, high-voltage pulse is applied from a tip of one electrode part of two electrode parts 22 and 23, e.g., the electrode part 22, so that an insulation breakdown is generated between the silicon rod 1 and the electrode part 22; and shock waves are generated, and transmitted through the silicon rod 1. By the shock waves, a crack C is generated in the silicon rod 1, or the silicon rod 1 is fragmented. By grounding the other electrode part 23, the applied high-voltage pulse flows into the electrode part 23; and a part of the high-voltage pules flows to the ground by surface transmission between the electrode parts 22 and 23.

[0040] Although it is not necessarily limited, the silicon rod 1 on which this fragmenting method is applied is disposed in a prescribed vessel in a state of being insulated from the vessel, and prepared in a state of being soaked in liquid. Although the shape of the silicon rod 1 is not especially restricted, an arrangement is preferable so that a distance between the electrodes and the silicon rod 1 be in a prescribed range in order to apply the high-voltage pulse in a certain state. For example, it is preferable to dispose mutually to have substantially a constant distance of top end sides of the electrodes with respect to a side surface of a major axis of the rod. A size of the silicon rod that can be relatively easily handled is, for example, a diameter is about 50 mm or more and about 200 mm or less and a length is about 30 cm or more and about 2000 cm or less. A distance from the electrode parts 22 and 23 to the surface of the silicon rod 1 is preferably about 2 mm or more and about 50 mm or less; and a distance between the electrode parts 22 and 23 is preferably about 30 mm or more and about 100 mm or less. It is preferable that a voltage of the applied high-voltage pulse be about 100 kV or more and 300 kV or less, power per one pulse be 300 J or more and 1000 J or less, and frequency of the high-voltage pulse be about 0.5 Hz or more and 40 Hz or less.

[0041] Setting value of the above-described fragmenting setting condition can be modified according to the configuration of the equipment: it is preferable to set appropriately considering the form and the size of the fragmented objects, while forming the fragmented object or forming the cracks.

[0042] Into the liquid, by the shock when the high-voltage pulse is applied, a part of the electrode parts 22 and 23 is derived as abrasion chips and spread to the vicinity of the electrode parts 22 and 23 and to the part to which the high-voltage pulse is applied of the silicon rod 1. The derivation and the spread of the abrasion chips of the electrode parts are increased with increasing of the number of applying times.

[0043] Therefore, new fluid is supplied to at least one of the part to which the high-voltage pulse is applied of the silicon rod 1 and the electrode parts 22 and 23. FIG. 1 shows a state of supplying the new fluid toward the electrode parts 22 and 23 and toward an electric discharging region applied on the surface of the silicon rod 1: supplying ports 31 of supplying nozzles 30 for supplying the new fluid and a discharging port 33 of a discharging pipe 32 are disposed in the vicinity of the electrode parts 22 and 23 and a region on which the high-voltage pulse is applied, so that the new fluid is continuously supplied. Thereby the abrasion chips derived from the electrode parts 22 and 23 are removed from the part to which the high-voltage pulse is applied and the vicinity of the electrode parts 22 and 23.

[0044] The supplying nozzles 30 for the new fluid and the discharging pipe 32 are preferably disposed to have a certain distance from the electrode parts 22 and 23 and the high-voltage pulse applied part so as not to be influenced from the electric discharge accompanying application of the high-voltage pulse applying.

[0045] Thereby, a successive flow of the new fluid is generated around the part to which the high-voltage pulse is applied and the vicinity of the electrode parts 22 and 23 as shown by the solid arrows. This flow becomes a flow (a carrier flow) carrying the abrasion chips of the electrode parts derived accompanying the application of the high-voltage pulse; and the abrasion chips are removed with the flow from the part to which the high-voltage pulse is applied and the vicinity of the electrode parts 22 and 23. As a result, it is possible to prevent the contamination by the abrasion chips taken into the minute cracks formed on the surface of the silicon rod 1.

[0046] In this case, the new fluid flows in a different direction from a direction of the high-voltage pulse applied from the electrode part 22 (a direction from the tip of the electrode part 22 toward the silicon rod 1, a direction from the silicon rod 1 toward the electrode part 23). Specifically, it is preferable to supply the liquid in a different direction from a direction (a direction shown by the arrow A in FIG. 1) from the electrode parts 22 and 23 toward the silicon ingot 1 in an imaginary line in which the distance from the tips of the electrode parts 22 and 23 to the silicon ingot 1 is shortest, in order that the direction of the generation of the high-voltage pulse and the flow direction of the flow are different directions. The abrasion chips generated from the electrode parts 22 and 23 (especially the electrode part 22) accompanying the application of the high-voltage pulse go toward the silicon rod 1 side along with the shock wave; in a process of fragmenting the silicon rod 1 or generating cracks, they cause the contamination by being taken into the minute cracks generated on the surface. Therefore, the abrasion chips derived from the electrode parts 22 and 23 can be kept away from the silicon rod 1 by generating the flow of the new fluid successively in the different direction from a direction of electric field, and the contamination can be avoided or reduced. The supplying ports 31 and the discharging port 33 may be disposed to face each other.

[0047] In this case, in order to efficiently supply the liquid, it is desirable to dispose the supplying ports 31 in the vicinity of the part of the silicon ingot 1 to which the high-voltage pulse is applied or the vicinity of the electrode parts 22 and 23; however, there is a case of occurring damages and abrasion of the supplying ports 31 by being influenced of the shock wave accompanying the application of the high-voltage pulse, it is prone to be influenced by the contamination of the material of the supplying ports 31 of the new fluid and the material contamination of the new fluid itself. Therefore, it is desirable that the arrangement of the supplying ports 31 of the new fluid is an arrangement in a state with a certain distance from the part to which the high-voltage pulse is applied or the electrode parts 22 and 23.

[0048] It is desirable to decide a discharging amount in accordance with a supplying amount of the new fluid. Since the abrasion chips of the electrode parts in the vessel is relatively increased if the supplying amount of the new fluid is more than the discharging amount, it is desirable that the discharging amount is at least the same as the supplying amount or more than the supplying amount.

[0049] In a case in which the discharging amount is more than the supplying amount, since a liquid amount in the vessel is gradually reduced, it is desirable to supply the liquid into the vessel in a case in which the liquid amount is less than a certain amount in order that the whole silicon rod 1 is soaked or the electrode parts are soaked in the liquid so as to be at least a state in which the high-voltage pulse can be applied.

[0050] The supplying amount of the new fluid is, although it depends on an applying condition of the high-voltage pulse, preferably 90 L/min. or more, more preferably 100 L/min. or more. If the supplying amount of the new fluid is small, it may prone to rise the influence of the contamination on the surface of the fragmented objects by the spread of the abrasion chips since the spread of the abrasion chips of the electrode parts accompanying the application of the high-voltage pulse is more than engulfing by the flow of the new fluid.

[0051] In this embodiment, also after the cracks are formed or the silicon rod 1 is fragmented, by supplying the new fluid successively to the fragmented objects or cracked objects so as to generate the flow therearound, the spreading abrasion chips of the electrode parts 22 and 23 are removed by the carrier wave, and a probability of taken into the minute cracks generated when the high-voltage pulse is applied is even more reduced. As a result, also in the semiconductor material lumps after forming cracks or fragmented, the contamination by the abrasion chips derived from the electrode parts is effectively reduced.

[0052] The fluid is easy to be handled since it is water or pure water; it is possible to fragment under supplying high-purity liquid or fluid using pure water, furthermore, an influence by impurities other than the electrode material can be reduced.

[0053] If the liquid or the new fluid in which the silicon rod 1 is disposed has bubbles, the bubbles collapse by the application of the high-voltage pulse, so that the abrasion chips are even more difficult to be taken into the minute cracks by the shock and the like, and an effect of reducing the adhesion on the surface of the semiconductor material lumps after fragmenting can be expected.

[0054] Furthermore, diffusing the minute bubbles with a diameter of 100 μm or less evenly in the liquid in which the silicon rod 1 is disposed or the fluid which is newly supplied, an effect of floating and diffusing by an absorbing the abrasion chips of the electrode material on the surface of the minute bubbles can be expected. It is expected to obtain the same effect also by existing the minute bubbles in the water and the pure water in an even diffused state. It is more desirable that the minute bubbles are bubbles of nano level (nm).

[0055] Next, explained is a method of producing the semiconductor material lumps to be the material for producing monocrystalline silicon using the above-described fragmenting method or the crack generation method.

[0056] The producing method of the semiconductor material lumps according to the present embodiment includes as a main process: a making step of a rod-shape material making the rod-shape silicon rod 1 by deposition of silicon in a furnace; and a fragment step by fragmenting by the fragmenting method described above or fragmenting after at least cracks are generated to make the silicon rod 1 to the semiconductor material lumps. Furthermore, it includes a cleansing step, a drying step, a packaging step and the like performed on the semiconductor material lumps after the fragment step.

[0057] In the making step of a rod-shape material, the silicon rod 1 is obtained by touching material gas containing chlorosilane gas and hydrogen to a heated silicon core rod to deposit silicon on the surface in substantially a columnar shape.

[0058] In the fragment step, the semiconductor material lumps are obtained by fragmenting the silicon rod 1 by the above-described method or fragmenting after at least cracks are generated. The fragmented silicon rod 1 is used which is preferably cleansed by pure water in advance. More preferably, one may be used in which surface impurities are removed by etching by chemicals.

[0059] The semiconductor material lumps obtained by this fragment step are fragmented by the shock wave by the application of the high-voltage pulse, and can be formed in lumps having a desired size by settings or the like such as the applied voltage, the applied recovery, a distance between the electrodes and the semiconductor material lumps. Thereby, it is not necessary to use a hammer or a mechanical fragmenting device thereafter; or even in a case of using the hammer or the mechanical fragmenting device, it can be managed with a minimum use to fragment a lump in which a crack is generated, so that it is relatively easy to fragment and a fragmenting workload is small, so that a contact with the metal material accompanying fragmenting can be small and the metal contamination can be reduced.

[0060] When fragmenting, the electrode part 22 and 23 and the silicon rod 1 are relatively moved in a diameter direction and a length direction of the silicon rod; it is preferable that 0.5 pulse or more and 1.0 pulse or less be applied per 1 mm of the relative movement.

[0061] The cleansing step is a step of removing impurities adhered on the surface of the semiconductor material lumps using chemicals such as acid and washing the acid away by pure water.

[0062] In the drying step, the semiconductor material lumps washed by the pure water are put in a dryer to dry them.

[0063] In the packaging step, the semiconductor material lumps are inspected in size and appearance, and stored in a packaging bag made of resin (e.g., made of polyethylene).

[0064] In the producing method of the semiconductor material lumps of the present embodiment, the cracks are generated in the silicon rod 1 to fragment them by the above-mentioned fragmenting method; so that the purity of the fragmented polycrystalline silicon lumps can be maintained high. Accordingly, the semiconductor material lumps obtained by this method can maintain the quality of monocrystalline silicon produced from them.

[0065] The embodiment is an example of providing one supplying port of the new fluid; by providing a plurality of supplying ports and a plurality of supplying direction, the new fluid can be more efficiently supplied to the part of the semiconductor material where the high-voltage pulse is applied and the like.

EXAMPLES

Example 1

[0066] Table 1 shows a result of confirming states of derivation and spreading of the abrasion chips from the electrode parts accompanying the application of the high-voltage pulse.

[0067] The state of generation of the abrasion chips of the electrode parts in pure water by the application of the high-voltage pulse is confirmed by inserting the electrode parts (an electric voltage application part, a ground part) in the pure water filled in a vessel. The applied voltage is about 170 kV and the distance between the electrodes is about 100 mm. Polycrystalline silicon material is not used; only the electrode parts are soaked in the pure water. Confirmed are two cases in which the new fluid (pure water) is supplied to the electrode parts in the vessel and in which the new fluid is not supplied. The pulse application is performed 10 times.

[0068] The abrasion chips are confirmed by analyzing concentration of the electrode material respectively in the pure water collected in the vicinity of the electrode parts about one minute after the high-voltages pulse is applied and in the pure water within the vessel distant from the electrode parts after the high-voltage pulse is applied. In a case in which the new fluid (pure water) is supplied, the pure water in the vicinity of the electrode parts is collected in a position opposite to the fluid supplying position with the electrode parts therebetween.

[0069] The concentration of the electrode material in the collected pure water is measured by a method of ICP emission spectrochemical analysis (inductive coupling plasma emission spectrometry).

[0070] The concentration of the electrode material in the pure water in the vessel before the application of the high-voltage pulse is less than 1.0 ppbw.

TABLE-US-00001 TABLE 1 New Fluid New Fluid Not Supplied Supplied (ppbw) (ppbw) Vicinity of 56 50 Electrode Parts Inside Vessel 41 12

[0071] By applying the high-voltage pulse, a part of the material (the abrasion chips) of the electrode parts from the electrode parts is derived in the vicinity of the electrode parts and spread along with the application of the pulse; although a degree of the spread is uneven, it is confirmed that the concentration of the electrode material in the vicinity of the electrode parts is higher comparing with that in a position at a distant from the electrode parts in the vessel. In the case, as shown in Table 1, by supplying the new fluid, it is inferred that the abrasion chips derived around the electrode parts are moved along with the flow of the fluid from the vicinity of the electrode parts, so that the concentration of the electrode material in the pure water is reduced. Since it can be appeared that the spread of the derived abrasion chips from the vicinity of the electrode parts to the whole inside the vessel is reduced by forming the flow of the fluid, it can be found it is effective for prevention of contamination to the semiconductor material.

[0072] When supplying the above-described new fluid, pure water is injected at about 20 L/min. using a blade hose made of resin.

[0073] Regarding the abrasion chips derived from the electrode parts in the high-voltage pulse fragmentation in the present example, the size is several μm in a confirmation of collecting by filtering by a filter; and it is also found that hydroxide of oxide of the electrode material (hydroxide of iron oxide FeO) is included in the confirmation of the collected abrasion chips by Raman spectroscopy.

Example 2

[0074] Table 2 shows a result of confirming a state of contamination on the surface of fragmented material accompanying the application of the high-voltage pulse.

[0075] A rod-shape polycrystalline silicon material block with a diameter of about 110 mm and a length about 1000 mm is soaked in pure water filled in the vessel; the high-voltage pulse is applied on the material block at a condition of voltage of about 170 kV, a distance between fragmented material and the electrodes of about 30 mm, a frequency of 1 Hz; and a degree of contamination of electrode parts material contamination is confirmed on the surface of silicon after the application (after fragmenting). The new fluid (pure water) is supplied to the pulse application part, the electrode parts and the fragmented material (before and after the fragmentation) with a prescribed amount (about 90 L/min.).

[0076] The new fluid (pure water) has two patterns of (1) a case supplying to the electrode parts and therearound and (2) a case supplying both to the electrode parts and therearound and the material after fragmentation; and concentration of the fragmented material is measured respectively in a case in which the supplied fluid is drawn and removed and a case in which the supplied fluid is not drawn and not removed. The pure water is collected at a position opposite to the fluid supplying position with intervening the electrode parts; in a case in which the supplied fluid is drawn and removed, it is downstream of the position of drawing and removing.

[0077] Concentration of contamination of the electrode part material on the surface of the fragmented material is analyzed by ICP-MS method (inductive coupling plasma mass spectrometry) after fragmenting.

[0078] The number of samples is three (n=3); the minimum value and the maximum value are shown.

TABLE-US-00002 TABLE 2 Not Drawn and Drawn and Position of Supplying Removed Removed New Fluid (1) (2) (1) (2) Concentration of 0.021- 0.020- 0.010- 0.008- Fragmented Material 0.055 0.045 0.018 0.013 (ppbw)

[0079] From the result of Table 2, the result is that the contamination on the surface of the material lumps is uneven and the degree thereof is high by discontinuously supplying pure water comparing to by continuously supplying fluid.

Example 3

[0080] Table 3 shows a result of confirming the state of contamination on the surface of the fragmented material in a case in which bubbles (nano bubbles) are included in the liquid and the new fluid.

[0081] The condition of the application of the high-voltage pulse is the same as in Example 2; the new liquid is supplied at the same condition as in Example 2 to both the electrode parts and therearound and the material after fragmenting; the pure water is drawn and removed at the opposite side position to the fluid supplying position with intervening the electrode parts; and then the fragmented polycrystalline silicon is taken out from the vessel and dried, and the concentration of the electrode material on the surface of silicon is measured as in Example 2.

[0082] The number of samples is three (n=3); the minimum value and the maximum value are shown.

TABLE-US-00003 TABLE 3 Bubbles included Concentration of Fragmented 0.010-0.015 Material (ppbw)

[0083] As known from Table 3, in the fragmentation by the application of the high-voltage pulse using the liquid and the new fluid including the bubbles it is confirmed that there is effect of reducing the influence of the contamination of the abrasion chips of the electrode parts comparing with a case in which the bubbles are not included.

Example 4

[0084] Table 4 shows the result of confirming a state of contamination on the surface of the fragmented material depending on the supplying direction of the new fluid.

[0085] The liquid and the new liquid are pure water; the electrodes and the semiconductor material are soaked in the pure water; and the high-voltage pulse is applied on the semiconductor material via the electrodes to fragment it. A polycrystalline silicon rod (about 1.5 m, a diameter about 120 mm) is used as the semiconductor material. Two types of the supplying direction of the new fluid are performed: (1) a direction of about 90° to an imaginary line between the electrodes and the semiconductor material (disposing the fluid supplying ports at an one end side of the semiconductor material (this side of the paper) and disposing the discharging port at the other end side of the semiconductor material intervening the imaginary line (the far side of the paper) in FIG. 1) (2) a direction toward the semiconductor material from the electrodes in substantially a parallel direction to the imaginary line. The fluid (pure water) is supplied continuously into the liquid (pure water) at a flow rate of about 40 L/min. and drawn and removed from the discharging port. It is continuously supplied toward the vicinity of the electrodes, the application part of the discharged pulse to the semiconductor material, the semiconductor material fragmented by the application of the discharged pulse and the vicinity thereof (the supply amount of the pure water to the water bath and the discharge amount are in a range of substantially the same fixed amount within a unit time). The semiconductor material is fragmented into size having a maximum side length of about 30 mm. The fragmented objects are collected from the liquid and dried to measure the surface impurities.

[0086] The concentration of contamination of the electrode part material on the surface of the fragmented material is analyzed by the ICP-MS (inductive coupling plasma mass spectrometry) method as in Example 2.

[0087] The number of samples is five (n=5); the minimum value and the maximum value are shown.

TABLE-US-00004 TABLE 4 Direction of Fluid (1) Direction of Fluid (2) Concentration of Impurities 0.006-0.011 0.023-0.086 on Surface of Fragmented Object (ppbw)

[0088] Regarding the direction of supplying the new fluid when fragmenting by the high-voltage pulse, depending on the direction when the direction of the fluid is parallel to the imaginary line between the electrode parts and the semiconductor material, there is a possibility of that the concentration of impurities is uneven by the abrasion chips of the electrode parts deriving and spreading into the fluid or the liquid adhere on the surface of the fragmented objects or are taken into the surface of the fragmented objects. As known from the result in Table 4, in order to reduce them stably, preferably, the supplying direction of fluid is preferably a different direction from the direction toward the fragmented objects (the semiconductor material). It is desirable to draw and discharge in a case in which the liquid in the vessel and the supplied fluid are discharged to the supply direction of the new fluid. By drawing and discharging, it is possible to form the flow of the new fluid with efficiency.

[0089] Iron is used as the material of the electrode parts used for applying the high-voltage pulse in the present invention; however, electric conductive material other than iron may be used if it is material of the electrode part which can apply the high-voltage pulse. For example, it may be the electrode parts of material such as silver or the like.

[0090] In the present invention, an integrated type electrode parts are used as a structure of the electrode parts; however, it may be a structure of the electrode parts configured from detachable members of the same material in which the electrode parts can be partly replaced such that only defects by abrasion of the electrode parts are replaced. As mounting/dismounting methods, for example, screwing, combination, welding or the like can be cited.

INDUSTRIAL APPLICABILITY

[0091] The present invention can be utilized when producing the semiconductor material lumps by fragmenting the semiconductor material such as a silicon rod or the like.

REFERENCE SIGNS LIST

[0092] 1 Silicon rod (semiconductor material) [0093] 22, 23 Electrode parts [0094] 30 Supplying nozzle [0095] 31 Supplying port [0096] 32 Discharging pipe [0097] 33 Discharging port