CN101631900A - System and method of forming a crystal - Google Patents
System and method of forming a crystal Download PDFInfo
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- CN101631900A CN101631900A CN200780044560A CN200780044560A CN101631900A CN 101631900 A CN101631900 A CN 101631900A CN 200780044560 A CN200780044560 A CN 200780044560A CN 200780044560 A CN200780044560 A CN 200780044560A CN 101631900 A CN101631900 A CN 101631900A
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Abstract
A system for producing a crystal formed from a material with impurities has a crucible for containing the material. The crucible has, among other things, a crystal region for forming the crystal, an introduction region for receiving the material, and a removal region for removing a portion of the material. The crucible is configured to produce a generally one directional flow of the material (in liquid form) from the introduction region toward the removal region. This generally one directional flow causes the removal region to have a higher concentration of impurities than the introduction region.
Description
Right of priority
That present patent application requires is that on December 6th, 2006 submitted to, name is called " UTILIZINGLOWER PURITY FEEDSTOCK IN SEMICONDUCTOR RIBBONGROWTH ", the invention people U.S. Provisional Patent Application the 60/873rd for David Harvey, Emanuel Michael Sachs, RichardLee Wallace Jr. and Weidong Huang, No. 177 right of priority is incorporated its whole disclosures into this paper by reference at this.
Present patent application also requires to submit on April 6th, 2007, name is called " UTILIZINGLOWER PURITY FEEDSTOCK IN SEMICONDUCTOR RIBBONGROWTH ", the invention people U.S. Provisional Patent Application the 60/922nd for David Harvey, Emanuel Michael Sachs, RichardLee Wallace Jr. and Weidong Huang, No. 355 right of priority is incorporated its whole disclosures into this paper by reference at this.
That present patent application also requires to submit on April 27th, 2007, denomination of invention is " SYSTEMAND METHOD OF FORMING A CRYSTAL ", the invention people U.S. Provisional Patent Application the 11/741st for David Harvey, Emanuel Michael Sachs, Richard Lee Wallace Jr., Leo van Glabbeek and Weidong Huang, No. 372 right of priority is incorporated its whole disclosures into this paper by reference at this.
Technical field
The present invention relates in general to crystal growth, more specifically, the present invention relates to promote the system and method for crystal growing process.
Background technology
Silicon wafer has formed the structure piece of the semiconducter device as solar cell, unicircuit and MEMS device miscellaneous.These devices often have the carrier lifetime of variation, and this influences the performance of device.For example, have the silica-based solar cell in higher carrier life-span and can more effectively solar energy converting be become electric energy than silica-based solar cell with low carrier lifetime with high-level efficiency more.The carrier lifetime of device normally forms the function of impurity concentration in the silicon wafer of device.Therefore the higher device of efficient is often formed by the silicon wafer with lower impurity concentration.
Yet the impurity concentration of silicon wafer depends on the impurity concentration in the silicon material that forms this silicon wafer usually.Unfavorable is that the silicon material with lower impurity concentration is more expensive than the silicon material with higher impurity concentration usually.Therefore, do not increase production cost in the art and can't produce the higher device of efficient usually.
Summary of the invention
According to an embodiment of the invention, a kind ofly be used to produce the crystalline system, described crystal is formed by the material with impurity, and described system has the crucible that is used to hold this material.Wherein, this crucible has introducing zone that is used to form the crystalline crystalline region, is used to receive material and the removal zone that is used to remove a part of material.This crucible is configured to produce material (liquid form) and flows to removing the unidirectional substantially of zone from introducing the zone.This unidirectional substantially flowing makes that removing the zone has than introducing the higher impurity concentration in zone.
Some embodiments of crucible have narrow end, and this narrow end holds at least a portion and removes the zone.Other embodiments of crucible have the elongated shape that has length dimension and width dimensions.Crystalline region can introduced the zone and remove between the zone along length dimension.In addition, length dimension can be at least three times of width dimensions.In addition, be configured to the crucible illustrative unidirectionally substantially along its length flow to removing the regional guidance material.
Removing the zone can adopt in many different modes any to remove material.For example, remove the zone and can have the removal port that is used to remove a part of material, this removal port and crystalline region are spaced apart.Therefore system can have and is used to impel material by removing the pressure source of port, or relies on the gravity charging.In order to receive the material of removal, this system can also have and remove the container that port connects.Alternatively, or additionally, this system also can have and passes the wick that is used to remove material (wick) of removing the zone.
Crucible can be constructed such that material has from introducing the zone to removing the basic impurity level that increases in zone.For example, unidirectional substantially flowing can make the removal zone have the impurity concentration higher than the mean impurity concentration in the crystalline region.
In some embodiments, crucible be substantially flat and hold material by surface tension.In addition, crucible can be constructed such that material is in crystalline region or be right after in the zone of crystalline region and do not have rotational flow substantially.Also can expect various embodiments a plurality of crystal that can be used to grow.In this case, crystalline region comprises many a plurality of crystalline crystal sub-region that are used to grow.
According to another implementation of the invention, a kind of crystalline method of making is added material in the introducing zone of crucible to.To be similar to the mode of crucible discussed above, this crucible has crystalline region equally and removes the zone.This method makes material flow in unidirectional substantially mode in the direction of removing the zone then.At least some impurity are removed the zone with unidirectional flowing to.This method is also removed a part of material from removing the zone.
According to another implementation of the invention, a kind of drawstring system is used to make the band crystal (ribbon crystal) that is formed by the silicon with impurity, and described drawstring system comprises the crucible that is used for receiving fluids silicon.In the mode of above-mentioned those embodiments, crucible has the introducing zone that is used to form the crystalline crystalline region, is used to receive silicon and is used to remove the removal zone of the silicon of a part of liquid form.Crucible is configured to produce material and flows to unidirectional substantially silicon (liquid form) of removing the zone from introducing the zone.This unidirectional substantially flowing makes that removing the zone has than introducing the higher impurity concentration in zone.
According to another implementation of the invention, a kind of manufacturing band crystalline system that is used for, described band crystal is formed by the material with impurity, and described system has the crucible that is used to hold this material.These crucibles also have introducing zone that is used to form the crystalline crystalline region, is used to receive material and the removal zone that is used to remove a part of material.Crucible is constructed such that most substantially material is substantially directly from introducing the zone to removing zone flows.Should flow and make that removing the zone had than introducing the higher impurity concentration in zone.
Description of drawings
Understand the advantage of various embodiments of the present invention the description of " embodiment " that the accompanying drawing that those skilled in the art should summarize is discussed more fully below following reference.
The schematically illustrated silicon ribbon crystal growing furnace that can implement illustrated embodiment of the present invention of Fig. 1.
The part sectioned view of the crystal growing furnace shown in the schematically illustrated Fig. 1 of Fig. 2.
The schematically illustrated crucible of Fig. 3 A according to illustrated embodiment structure of the present invention.
The embodiment of the crucible of the schematically illustrated receiving fluids silicon of Fig. 3 B and a plurality of silicon ribbon wafers of growing.
Fig. 4 illustrates the example of the impurity concentration in the melting material of crucible with graphic representation.
The sectional view of the schematically illustrated crucible as shown in Fig. 3 B of Fig. 5.
The longitudinal sectional view of the part of the crucible shown in the schematically illustrated Fig. 3 A of Fig. 6.
The outlet port of the schematically illustrated crucible of Fig. 7 A and according to the part sectioned view that is used to make the device that melt substance topples over of first embodiment of the invention.
The outlet port of the schematically illustrated crucible of Fig. 7 B and according to the part sectioned view that is used to make the device that melt substance topples over of second embodiment of the invention.
The outlet port of the schematically illustrated crucible of Fig. 7 C and according to the part sectioned view that is used to make the device that melt substance topples over of third embodiment of the invention.
The schematically illustrated part sectioned view that is used to make the device that melt substance topples over of Fig. 7 D and 7E according to four embodiment of the invention.
Fig. 8 illustrates the method for toppling over according to the melt substance of illustrated embodiment of the present invention.
The top view of the schematically illustrated crucible according to replacement embodiment of the present invention of Fig. 9 with narrow end.
The orthographic plan of three other alternate embodiments of Figure 10 A, 10B and the schematically illustrated crucible of 10C.
Embodiment
In illustrated embodiment, crystal growth system has crucible, and this crucible is configured to come the higher crystal of workmanship by the lower starting material of quality.Therefore, this system can reduce the crystal production cost, correspondingly reduces by these crystal formation device cost.
For this reason, this crucible has the zone of removal, is used for optionally removing the higher melting material of impurity that is washed into this removal zone by unidirectional substantially flowing.More particularly, this flow make many impurity (along with flowing of material) in the material from the upstream region of crucible to removing zone flows.Use the test of silicon melt substance to show, this flows and makes impurity accumulate in the removal zone.
Remove material and have the net effect of from crucible, removing impurity from removing the zone, therefore can make this system's manufacturing have crystal than low impurity concentration.Discuss the details of illustrated embodiment below.
The schematically illustrated silicon ribbon crystal growing furnace 10 that can implement illustrated embodiment of the present invention of Fig. 1.Wherein, stove 10 has the shell 12 that forms sealed inside, and sealing inside does not have oxygen (to prevent burning) substantially.It is not the another kind of gas or the mixed gas such as argon of oxygen that this inside has certain density.Wherein, this enclosure is also held crucible 14 and other parts (some of them are discussed below), and four silicon ribbon crystal 3s 2 are used for growing substantially simultaneously.Band crystal 32 can be any in the various crystal types, such as multiple crystalline substance, monocrystalline, compound crystal, crystallite or semi-crystalline.Opening for feed 18 in the shell 12 provides the device that is used for silicon material is directed to interior crucible 14, and simultaneously, optionally window 16 makes it possible to the parts of inside are checked.
The discussion that should be noted in the discussion above that silicon ribbon crystal 32 is illustrative, is not used for limiting all of the embodiments of the present invention.For example, crystal can be formed by the combination of the material except silicon or silicon and other material.As another example, illustrated embodiment can form non-band crystal.
The part sectioned view of the crystal growing furnace 10 shown in the schematically illustrated Fig. 1 of Fig. 2.Wherein, this view illustrates above-mentioned crucible 14, and this crucible 14 is supported on the inside panel 20 in the shell 12, and has the top surface of substantially flat.As shown in Figure 3A, this embodiment of crucible 14 has elongated shape, has along the grow zone of silicon ribbon crystal 32 of its length being used to of being arranged side by side.
In illustrative embodiment, crucible 14 is made and is resistively heated to by graphite and silicon can be maintained its temperature more than fusing point.In order to improve the result, crucible 14 has the length much larger than its width.For example, the length of crucible 14 can be three times or more times of its width.Certainly, in some embodiments, crucible 14 is not elongated like this.For example, crucible 14 can have roughly foursquare shape, or the shape of non-rectangle.For the sake of simplicity, all embodiments of crucible are by Reference numeral 14 expressions.
The zone that can think that crucible 14 has three independences but connect: just, 1) is used for receiving the introducing zone 22 of silicon materials from shell opening for feed 18; 2) four the crystalline regions 24 that are used to grow with crystal 32; With 3) the removal zone 26 that is used to remove a part of molten silicon (that is, toppling over operation) that holds by crucible 14.In the embodiment shown, remove zone 26 and have the port 34 that is used to make the silicon removal.Yet, as be discussed in more detail below, other embodiments do not have this port 34.
To be similar to the mode of other aspects of the present invention, the discussion of four crystal sub-region only is a kind of embodiment.All respects of the present invention can be used to have and (for example be less than four crystal sub-region, one, two or three sub regions) or greater than the crucible 14 of four crystal sub-region, therefore, the discussion of a crystal sub-region only is used for illustrative purpose, is not used for limiting all embodiments.In a similar fashion, the discussion more than one band crystal 32 is a kind of embodiment.Some embodiments only be applied to grow system of single band crystal 32.
The schematically illustrated embodiment of Fig. 3 B with crucible 14 of shallow perisporium 31.In addition, this illustrates receiving fluids silicon and the embodiment of this crucible 14 of four the silicon ribbon crystal 3s 2 of growing.As shown in the figure, the most close crystal sub-region of introducing zone 22 is called first subregion, growth " being with 3 ", and second subregion growth " being with 2 ".The 3rd subregion growth " being with 1 ", the most close the 4th subregion growth " being with 0 " of removing zone 26.As is known to the person skilled in the art, the crystal growth of successive silicon ribbon can be implemented by wear two high-temperature material lines of cable-through hole 28 introducings in crucible 14.This line stabilization the edge of zone of growth crystal 32, and as mentioned above, the final fringe region that forms growth silicon ribbon crystal 32.
Shown in Fig. 3 B, the molten silicon that is upwards drawn and line and the coagulation band crystal 32 that exists on the top surface that just in time is higher than molten silicon combine.(be called " interface ") in this position, solid band crystal 32 is discharged a part of impurity usually from its crystalline structure.Wherein, this impurity can comprise iron, carbon, tungsten and iron.Therefore impurity thereby be expelled back in the molten silicon increased the impurity concentration in the crystalline region 24.In this process, each band crystal 32 preferably is drawn out from molten silicon with extremely low speed.For example, each band crystal 32 can utilize the about one inch speed of per minute to be drawn out from molten silicon.
According to illustrated embodiment of the present invention, crucible 14 is constructed such that molten silicon flows to removing zone 26 from introducing zone 22 with extremely low speed.If this flow rate is too high, growing crystal may be grown in unfavorable mode undesirablely, thereby availability reduces.This low flow makes and comprises those impurity of being discharged by growing crystal by a part of impurity that molten silicon is interior, flows to removing zone 26 from crystalline region 24.
Several Factors has contribution to molten silicon to the flow rate of removing zone 26.Each factor all relates to crucible 14 interpolation silicon or from crucible 14 removal silicon in these factors.Specifically, first factor in these factors is to be removed by the caused silicon of the physical motion that makes progress of melt substance by line fully.For example, four band crystal 3s 2 are removed with the speed of 1 inch of per minute, and wherein each band crystal 32 has about three inches width and the thickness between about 190 microns to about 300 microns, and per minute is removed about 3 gram molten silicons.Second factor in these factors of flow rate of influencing is from removing regional 26 selective removals/topple over molten silicon.
Therefore, in order to keep substantially invariable melt height, system adds new silicon material as the function of the melt height of expectation in the crucible 14.For this reason, wherein, this system can detect the resistance change of crucible 14, and described resistance is the function of the melt substance that holds in the crucible.Therefore, where necessary, system can add new silicon material according to the resistance of crucible 14 in crucible 14.For example, in some was implemented, melt height can be added the roughly spheric silico briquette with about several millimeters diameter by about each second usually and be kept.For example, referring in the following United States Patent (USP) (incorporating its whole disclosures into this paper by reference) about in crucible 14, adding silicon material and keeping the Additional Information of melt height:
·US6,090,199
US6,200,383 and
·US6,217,649.
Therefore, the flow rate of the molten silicon in the crucible 14 dosing silicon and caused by this basic successive/intermittence from crucible 14 removal silicon to crucible 14.Can be contemplated that under suitable low flow rate it is unidirectional substantially mobile mobile to removing zone 26 that the geometry of the various embodiments of crucible 14 and shape will make that molten silicon passes through.By having this unidirectional substantially flowing, most substantially molten silicon (whole substantially molten silicons) directly flows to removing zone 26.
When flowing by this way, some molten silicons will contact the extremely thin side of zone of growth crystal 32.As mentioned above, in illustrated embodiment, being with being somebody's turn to do of crystal 32 to approach the side can be between about 190 micron and 300 microns.In some embodiments, band crystal 32 can have thin 60 microns part according to appointment.Therefore, to removing the flowing of zone 26, should ignore substantially with respect to silicon by the caused resistance to flow in side of band crystal 32.Yet this resistance can cause that molten silicon is in some very little, insignificant local flow of not pointing on the direction of removing zone 26.Yet can expect that molten silicon can flow through this point reposefully, and not cause that impurity is except having remarkable motion on any direction of removing the zone 26.In fact, because their thin profile, in fact the band crystal 32 of growth can be considered to work as fin (fins), to guarantee/to promote to unidirectional substantially fluid flow of removing zone 26.
As mentioned above, crucible 14 can have other and is used to produce device to the mobile resistance of molten silicon; That is, in the embodiment shown, a plurality of ridges 30 are separated the different subregions of crystalline region 24.Similar to the side of zone of growth crystal 32, expect that equally these ridges 30 cause that molten silicon is in the insignificant local flow of not pointing on the direction of removing zone 26.In other words, in the lateral mode of the band crystal 32 that is similar to growth, these ridges 30 can produce the insignificant substantially local flow that is generally perpendicular to whole fluid flow direction.However, in the present embodiment, under the condition of low flow rate, most substantially silicon still flows to removing regional 26 longitudinal axis that also generally are parallel to crucible 14 in unidirectional substantially mode.This phenomenon can be by proving in the increase of removing regional 26 impurity concentrations, especially when with crystalline region 24 with when introducing impurity concentration in the zone 22 and comparing.
In other words, although some negligible partial fluid turbulent flows are arranged, the molten silicon stream of end face that passes some embodiments of crucible 14 has to unidirectional substantially fluid flow of removing zone 26.These are different with some prior art system, and described prior art system makes a large amount of molten silicons in crystalline region 24 or be right after in the zone of crystalline region 24 with basic annular or the circulation of other rotary movement.Be different from those prior art system, the aforesaid insignificant local silicon in illustrated embodiment flows and performance is not made significant difference, and does not therefore change the character to unidirectional substantially fluid flow of removing zone 26.
To the mobile result, the impurity concentration in the molten silicon is being introduced zone 22 and is being removed increase between the zone 26 usually as this basic folk prescription.This is increased in some zones than higher in other zone.Fig. 4 illustrates the example of this relation with graphic representation.Specifically, impurity concentration substantially constant in introducing zone 22.Because the above-mentioned impurity at crystal growth interface is discharged, impurity concentration improves in crystalline region 24.This discharge is also referred to as " segregation " in the art.Concentration is stabilized to higher substantially invariable concentration usually in removing zone 26.Be desirably in and remove in the zone 26 this higher concentration greater than the mean concns of crystalline region 24.In addition, expect that also this higher concentration is greater than the concentration in any part of introducing zone 22.
As shown in the figure, impurity concentration only changes in crystalline region 24.Therefore, the general downstream end of crystalline region 24 (from the angle of fluid flow) has and the essentially identical impurity concentration of impurity concentration of removing zone 26.In a similar manner, the cardinal principle upstream extremity of crystalline region 24 has and the essentially identical impurity concentration of impurity concentration of introducing zone 22.Yet this expression only is the generalized desirable expression of an embodiment.In fact, Shi Ji impurity concentration can change in All Ranges to a certain extent.
The impurity concentration of the variation in the crystalline region 24 influences in four zone of growth crystal 3s 2 impurity concentration of each.Particularly, the most approaching band crystal 32 of introducing zone 22 of expectation has comparison near the band crystal impurity still less of removing zone 26 usually.In fact, the impurity concentration of single band crystal 32 can change owing to this distribution.Some embodiments in fact can be by removing the removal zone 26 zone of growth crystal 3s 2 of many impurity.This embodiment can use or can not use removal port 34.
Any the hold molten silicon of crucible 14 in can be in many different ways.In illustrated embodiment, the end face of crucible 14 is smooth substantially, does not have sidewall 31 (for example Fig. 3 A).Therefore, the surface tension of molten silicon makes crucible 14 hold silicon substantially.Fig. 5 illustrates this by illustrating along crucible 14 sectional views of the width of crucible 14.It also shows the side of zone of growth crystal 32.Should be noted that to be similar to the mode of other figure.Fig. 5 is a synoptic diagram, so its size not drawn on scale.
Yet other embodiments of crucible 14 can have the perisporium 31 of different heights (for example, referring to Fig. 3 B).Therefore, substantially flat or flat crucible 14 or the discussion with crucible of wall 31 only are used for illustrative purposes, are not used for limiting many other embodiments of the present invention.
For the details of each illustrated embodiment is described, the schematically illustrated sectional view of Fig. 6 from a part of length of removing the crucible 14 of zone 26 to any Fig. 3 A that only crosses the first line hole 28.In this embodiment, crucible 14 has the port 34 of removal, and this removal port 34 has bigger interior dimensions in the top surface plane of crucible 14.Yet this interior dimensions is converged to the shape of basic truncated cone to the passage with very small inner dimension.This shape is effective as the funnel that is used to remove molten silicon to be toppled over.
The bottom illustration ground of removing port 34 has wicking action and keeps functional component 36, and this wicking action keeps functional component 36 to make the surface tension of molten silicon come balancing gravity.As more detailed discussion hereinafter, molten silicon can be removed port 34 by using vacuum, differential pressure or other device to be forced to leave.Yet, in some embodiments, relying on the aperture, flow, reach other functional components, molten silicon can leave under no auxiliary situation removes port 34.Alternatively, the interior dimensions of removal port 34 can be enough big so that gravity can removed molten silicon (for example, under the situation in no vacuum) equally under the no auxiliary situation.For example, in gravity removal system, molten silicon can form droplet, and this droplet separates with removal port 34 after reaching critical size/quality.The size of this droplet can be controlled according to the size of material category that is used for melt substance and removal port 34.
Fig. 6 more specifically illustrates many other functional components of crucible 14, such as the ridge 30 and the described line hole 28 of the surface that is projected into crucible 14 a little.To be similar to the mode of removing port 34, the interior dimensions that provides similar wicking action to keep functional component 36 equally is provided in line hole 28, thereby as effectively sealing.In addition, the crucible 14 shown in Fig. 6 also has consent 38, and this consent 38 helps to control the temperature of crucible 14.For this reason, according to desired temperatures, can increase and/or the removal insulation from consent 38.
Illustrated embodiment can be used many different from removing the technology that molten silicons are removed in zone 26.An above-mentioned this technology comprises by removing zone 26 growths sacrifices band crystal 32.Fig. 7 A can be used to from removing the various other technologies that high impurity molten silicon is removed in zone 26 to 7E is schematically illustrated.In these technology each can be used separately or use jointly with other technologies.The discussion that should be noted that these technology is not used for hinting do not have other can be used to remove the technology of molten silicon.In fact, each embodiment of the present invention can use other to be used for from removing the technology that silicon are removed in zone 26.
The schematically illustrated a kind of device of Fig. 7 A, this device provides little positive pressure to the top of removing port 34, is used for removing molten silicon from removing zone 26.For this reason, this device has endless tube (collar) 40, and this endless tube 40 has the opening end of the over top that is arranged on removal port 34 and the opposite end of sealing.The sealing end has and is used to receive the pipe 42 of pressurized gas such as argon gas, is used for carrying positive pressures to removing port 34.This device can be active or fixed.
System also has removable receptor 44, this receptor 44 be combined in the bottom periphery of removing port 34 be used to receive removal/molten silicon of toppling over.This receptor 44 can be positioned within the shell 12, be positioned at the outside of shell 12 or be positioned partially within the shell 12.In illustrated embodiment, receptor 44 be water-cooled and in the outside of shell 12.
Therefore, apply positive pressure to the top of removing port 34 and produce pressure difference, this pressure difference forces molten silicon droplets arrives the receptor 44 from removing port 34.The size of each droplet is by the density and the surface tension control of the interior dimensions of removing port and molten silicon.For example, the droplet that can produce about 0.9 gram of quality substantially for the removal port 34 of circular interior dimensions that has 4 millimeters.
Be not positive pressure or except that positive pressure, some embodiments apply little vacuum (for example about 800Pa below barometric point) (being negative pressure) from the bottom of removing port 34.For this reason, the schematically illustrated receptor 44 that applies vacuum to the export department of removing port 34 of Fig. 7 B.The receptor 44 of present embodiment can be similar to the above-mentioned receptor of being discussed about Fig. 7 A, connects (not shown) but have extra vacuum.In some embodiments, comprise other embodiments that this paper discusses, the outside that laser or photo-sensor can be set at stove 10 is to measure droplet isolating time.This can control the withdrawal gradually of vacuum tightness and droplet.For example, a drip melt melt material can be by in about 800 milliseconds, jumping the vacuum tightness of about 6iwc (inch of water) and in 200 milliseconds, drop to about 0 and be extracted out.Test verifiedly, use the self-timing program can extract 12 one controlled drops.
Schematically illustrated another embodiment that does not need wicking action to keep of Fig. 7 C.Different is that this embodiment optionally freezes (promptly solidifying) and the molten silicon that thaws drips with metering by removing the fluid flow of port 34.For this reason, this embodiment has the pipe 46 that is used to carry the gas jet of cooling off removal port 34.For example, gas jet can optionally be carried argon gas to removing port 34.This embodiment also can have the receptor 44 that is used to receive the silicon that abandons.Receptor 44 can be to be similar to above-mentioned those receptors of being discussed about Fig. 7 A and 7B.
Schematically illustrated another of Fig. 7 D and 7E is used for from removing the technology that impurity is removed in zone 26.Be different from technology discussed above, this technology does not need to remove port 34.Different is, this embodiment uses make a return journey impurity in the silica removal of wick (wick) 48.For this reason, this embodiment has wick assembly 49, and this wick assembly 49 is through wick 48, and this wick 48 is by the molten silicon in the crucible 14.The schematically illustrated sectional view of Fig. 7 D, and the schematically illustrated wick assembly 49 that closes within the shell 12 of Fig. 7 E with stove 10 of wick assembly 49.
In this embodiment, wick 48 can be formed by the material of the material that is similar to the line that is used to form band crystal 32.Particularly, wick 48 can be wrapped on the bobbin 51, and wick 48 is removed and is directed to crucible 14 from this bobbin 51.Motor 50 is moved wick 48 to pivot arm 52 from bobbin 51 such as the direct current stepper-motor, and this pivot arm 52 is guided wick 48 into crucible 14 again.Pivoting action on second electric motor 54 or the similar pivoting device control arm 52.Through crucible 14, this guide member 56A extends upward from the removal zone 26 of crucible 14 wick 48 by guide member 56A.
After wick 48 was passed molten silicon, silicon freezed/adheres to the outside surface of wick 48.Specifically, in order from molten silicon, to remove impurity, wick 48 can pass the surface of molten silicon or pass molten silicon than the deep branch.A pair of motorized rollers 58 forces to cover the silicon of wick 48 to its external position that can be dropped motion.
In illustrated embodiment, wick assembly 49 has common wick shell 60 in main shell 12 outsides.This wick shell 60 holds the various piece of wick assembly 49, such as roller 58, second motor 54 with from another guide member (not shown) of bobbin 51 (part illustrates) guiding wick 48.In the mode of the inside that is similar to main shell 12, this shell 60 can be equally basic anaerobic and be filled with some place of gas such as argon.The wick 48 that sealing member 62 can be between two shells 12 and 60 provides sealed interface.
In alternate embodiments, wick 48 is taked the form except that line.For example, wick 48 can be wet section or porous or a moistening material of pipe, band crystal, line.Alternate embodiments can make wick 48 contact molten silicon with mode identical with the mode shown in the 7E with Fig. 7 D or different modes.
As mentioned above, can utilize other technologies from crucible 14, to remove molten silicon.For example, can make silicon leave crucible 14 by the mode of temperature fluctuation.Therefore, the discussion of various silicon removal technology is the discussion for those concrete embodiments.
After the installation, system mainly makes silicon ribbon crystal 32 in a substantially continuous manner.Fig. 8 illustrates the simplified method that forms silicon ribbon crystal 32 according to illustrated embodiment of the present invention.Each step in this method can be continuously, substantially side by side and/or in the different time implement with different orders.Therefore, should be noted that each step of the parallel enforcement shown in Fig. 8 only is a kind of embodiment.
Specifically, step 800 is periodically added silicon material in the crucible 14 by the opening for feed in the stove outer covering 12 18.As mentioned above, this silicon material can have the impurity concentration higher than other starting material.However, illustrated embodiment allows to use this starting material to make the lower silicon ribbon crystal 32 of impurity concentration.Illustrated embodiment can be by any conventional apparatus such as utilizing moving belt that silicon material is moved in the opening for feed 18 with transmitting.Can with any traditional form such as with particle, sheet or fully the silicon material of the form of the material of crushing add in the opening for feed 18.In other embodiment, the silicon material with liquid form is added in the opening for feed 18.
Step 802 is passed through the silicon ribbon crystal 32 that line hole 28 in the crucible 14 forms monocrystalline or polycrystalline state in a conventional manner simply by making line.Step 804 is periodically removed molten silicon from removing zone 26 in aforesaid mode.In alternate embodiments, system removes solid silicon rather than removes molten silicon from removing zone 26 from removing zone 26.Though should be noted that the interpolation of silicon and topple over to be considered to " periodically ", this step can be implemented by predetermined distance, or implements off and on according to " needs ".
Embodiment discussed above is described as having basic orthogonal elongated shape with crucible 14.In alternate embodiments, crucible 14 can be taked some other non-rectangles, non-elongated or neither the non-elongated again shape of orthogonal.The schematically illustrated this embodiment of Fig. 9, wherein crucible 14 has wide relatively introducing zone 22, comprises the narrow end of removing zone 26 but be converged to.This embodiment of crucible 14 has many and discussed above crucible 14 similar functional components, for example line hole 28, four crystal sub-region and flow control ridges 30.Because the flow rate of its shape and expection, flowing of most substantially molten silicon will be assembled to removing zone 26 usually.
The shape of the crucible 14 shown in Fig. 9 and structure only are can being used in the lump of shape miscellaneous.Can use other crucibles 14 irregularly shaped or regular shape.In the case, the geometry of crucible 14 and shape, have promoted to the basic folk prescription of removing zone 26 to flowing such as the expected flow speed of molten silicon in conjunction with other consideration.
In other embodiment more of the present invention, crucible 14 can be elongated but crooked.In this case, if most substantially molten silicon along the outer edge of this crucible 14, molten silicon can be considered to be in unidirectional substantially mode and flow.Therefore, for example, though silicon can move by the arc mode, if most substantially silica-based bending and contour direction along crucible 14, this material flows and still is considered to unidirectional substantially.
Figure 10 A is to the schematically illustrated basic various embodiments that have one type crucible 14 removing zone 26 at the center of crucible of 10C.Specifically, in the embodiment shown in these figure, stove 10 is configured to be provided for add silicon material in the crucible 14 one or more zones.For example, according to Figure 10 A, almost circular crucible 14 utilizes the clock time position as a reference shown in the figure, in the twelve-hour position, three position, six-o ' clock position and nine o ' clock positions (or some similar interval regions) add silicon material.Therefore, introduce zone 22 and be considered to a kind of annular shape zone (being shape image circle cake), have four feed hole area at the external edge of the end face of crucible 14.The internal diameter of introducing zone 22 is obviously much bigger than the internal diameter of removing zone 26.
To be similar to the mode of introducing zone 22, crystalline region 24 is the annular shape zone of crucible 14 equally, and this crystalline region 24 is radially being introduced zone 22 and removed between the zone 26.The internal diameter of crystalline region 24 is therefore less than the internal diameter of introducing zone 22.With to the similar mode of embodiment of the crucible 14 shown in Fig. 3 A, these embodiments of crucible 14 thereby make crystalline region 24 radially introduce zone 22 and remove between the zone 26.Like this, for the same cause of aforesaid crucible 14 about Fig. 3 A, this embodiment of crucible 14 is constructed such that also most substantially material substantially directly flows to removing zone 26 from introducing zone 22.In these embodiments, most substantially molten silicon is to removing regional 26 convergent flow; That is to say, in this case, mobile to the general center of crucible 14.This embodiment does not provide unidirectional substantially and flows.Therefore, this fluid flow should make a part of impurity with moving to removing regional 26 mobile silicon.This should advantageously cause the increase of removing impurity concentration in the zone 26.
To be similar to the mode of the crucible 14 shown in Fig. 3 A, this embodiment should be unable to make molten silicon flow in the mode of circle equally.On the contrary, molten silicon radially flows on substantially linear ground from the outer radial removal zone 26 of crucible 14.
As mentioned above, the shape of crucible 14 in this embodiment can change.For example, Figure 10 A illustrates round-shaped crucible 14, and Figure 10 B illustrates the crucible 14 of elliptical shape.As another example again, Figure 10 C illustrates the crucible 14 of rectangular shape.Certainly, the crucible 14 of this embodiment can be taked other unshowned shapes, such as octagonal shape or some irregular shapes.If the shape of the crucible of this embodiment 14 is asymmetric, removing zone 26 so can be in the position of certain substantial middle.
Can be by the silicon crystal that illustrated embodiment is made as the substrate of semiconductor product miscellaneous.Wherein, for example, band crystal 32 can be cut into the wafer that forms high efficiency solar cell.
Therefore, various embodiments wash away many impurity from the crystalline region 24 of crucible 14 effectively.With 1) introduce the impurity concentration and 2 in zone 22) mean impurity concentration of crystalline region 24 compares, this wash away make impurity in removing zone 26 with high relatively concentrations build-up.Therefore various embodiments of the present invention help to be made by starting material more cheap, that impurity is higher the crystal of high quality (promptly having lower impurity concentration).Therefore, various semiconducter device efficiently can utilize lower cost manufacturing.
Although above-mentioned discussion discloses various illustrative embodiments of the present invention, should be appreciated that those skilled in the art can realize the various modifications of advantages more of the present invention, and do not deviate from the real protection domain of the present invention.
Claims (40)
1. one kind is used to produce the crystalline system, and described crystal is formed by the material with impurity, and this system comprises:
Crucible is used to hold described material and has introducing zone that is used to form described crystalline crystalline region, is used to receive described material and the removal zone that is used to remove a part of described material,
The described material that described crucible is configured to produce liquid form is removed the unidirectional substantially of zone and is flowed to described from the described zone of introducing,
Described unidirectional substantially flowing makes the described zone of removing have than the described higher impurity concentration in zone of introducing.
2. the system as claimed in claim 1, wherein said crucible has the elongated shape that has length dimension, described crystalline region along described length dimension between described introducing zone and described removal zone.
3. system as claimed in claim 2, wherein said crucible has width dimensions, and described length dimension is at least three times of described width dimensions.
4. the system as claimed in claim 1, wherein said crucible has length dimension and width dimensions, described crucible be configured to basic along its length folk prescription to ground to removing flowing of the described material of regional guidance.
5. the system as claimed in claim 1 further comprises and passes the described wick of removing the zone.
6. the system as claimed in claim 1, wherein said crucible are constructed such that described material has from the described zone of introducing to the described impurity level of removing the basic described material that increases in zone.
7. the system as claimed in claim 1, wherein said crucible is shaped as has narrow end, and at least a portion in described removal zone is positioned at described narrow end.
8. the system as claimed in claim 1, wherein said material is a silicon.
9. the system as claimed in claim 1, wherein said crystal is the silicon ribbon crystal.
10. the system as claimed in claim 1, wherein said crucible are constructed such that described material is in described crystalline region or be right after in the zone of described crystalline region and do not have rotational flow substantially.
11. comprising, the system as claimed in claim 1, described crystalline region be used to grow a plurality of crystal sub-region of a plurality of crystalline.
12. the system as claimed in claim 1, wherein said crucible be substantially flat and hold described material by surface tension.
13. the system as claimed in claim 1 further comprises the described material of liquid form, described material is held by described crucible.
14. the system as claimed in claim 1, wherein said removal zone has the removal port that is used to remove a part of described material, and described removal port and described crystalline region are spaced apart.
15. system as claimed in claim 14 further comprises being used to impel the pressure source of material by described removal port.
16. system as claimed in claim 14 further comprises the container that connects with described removal port, described container is admitted the material of removing via described port.
17. the system as claimed in claim 1, wherein said unidirectional substantially flowing makes described removal zone have the impurity concentration higher than the mean impurity concentration of described crystalline region.
18. one kind forms the crystalline method, described method comprises:
With the introducing zone that material adds crucible to, described crucible also has and is used to produce described crystalline crystalline region, and described crucible further has the zone of removal;
Make described material flow in unidirectional substantially mode along the described direction of removing the zone, at least some impurity are with described unidirectional described removal zone that flow to; With
Remove a part of described material from described removal zone.
19. method as claimed in claim 18, wherein said crystalline region has first impurity concentration, and described removal zone has second impurity concentration, and described second impurity concentration is greater than described first impurity concentration.
20. method as claimed in claim 18, wherein said material comprise that silicon and described crystal are the silicon ribbon crystal.
21. method as claimed in claim 18 wherein saidly unidirectionally is flowing in the described crystalline region or does not have rotational flow substantially in being right after the zone of described crystalline region.
22. method as claimed in claim 18, wherein the removal of the described material of at least a portion makes described material flow in unidirectional substantially mode along the described direction of removing the zone at least in part.
23. method as claimed in claim 18, use surface tension to hold described material wherein feasible comprising at least.
24. method as claimed in claim 18, wherein said crystalline region is between described introducing zone and described removal zone.
25. method as claimed in claim 18, make described material flow in unidirectional substantially mode towards described removal zone property direction along the line wherein feasible comprising.
26. a drawstring system is used to produce the band crystal that is formed by the silicon with impurity, described system comprises:
Crucible, the removal zone that is used for receiving fluids silicon and has the introducing zone that is used to form described crystalline crystalline region, is used to receive silicon and be used to remove the described silicon of a part of liquid form,
The described silicon that described crucible is configured to produce liquid form is removed the unidirectional substantially of zone and is flowed to described from the described zone of introducing,
Described unidirectional substantially flowing makes the described zone of removing have than the described higher impurity concentration in zone of introducing.
27. system as claimed in claim 26, wherein said crucible has the elongated shape that has length dimension, described crystalline region along described length dimension between described introducing zone and described removal zone.
28. drawstring as claimed in claim 26 system, it is right that wherein said crystalline region has a plurality of lines hole.
29. drawstring as claimed in claim 26 system, wherein said crucible is smooth substantially and holds described silicon by surface tension.
30. drawstring as claimed in claim 26 system, wherein said crystalline region comprises a plurality of a plurality of crystalline crystal sub-region that are used to grow.
31. one kind is used for producing band crystalline system, described band crystal is formed by the material with impurity, and described system comprises:
Crucible is used to hold described material and has introducing zone that is used to form the crystalline crystalline region, is used to receive described material and the removal zone that is used to remove a part of described material,
Described crucible is constructed such that basic all materials are substantially directly regional to described removal zone flows from described introducing,
Described flowing makes the described zone of removing have than the described higher impurity concentration in zone of introducing.
32. system as claimed in claim 31, wherein said removal zone is positioned at the approximate centre of described crucible, the mobile approximate centre that is directed to described crucible of described material.
33. system as claimed in claim 31, wherein said crucible has the shape of essentially rectangular.
34. system as claimed in claim 31, wherein said crucible has the shape or the oval in shape of circular.
35. system as claimed in claim 31, wherein said crucible has the external edge in the outside, and described introducing zone is than more close described external edge, described removal zone.
36. system as claimed in claim 35, wherein said crystalline region is between described introducing zone and described removal zone.
37. system as claimed in claim 31, wherein said crucible has elongated shape, and described crucible is configured to produce the described material of liquid form from described unidirectional substantially flowing from the zone to described removal zone that introduce.
38. system as claimed in claim 31, wherein said crucible is constructed such that most substantially described material is to described removal zone convergence.
39. system as claimed in claim 31, wherein said crucible is constructed such that described material is in described crystalline region or be right after in the zone of described crystalline region and do not have rotational flow substantially.
40. system as claimed in claim 31, wherein said introducing zone comprises a plurality of introducings zone, and described crystalline region comprises a plurality of crystalline regions, and each is introduced the zone and has the crystalline region that is associated.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US87317706P | 2006-12-06 | 2006-12-06 | |
| US60/873,177 | 2006-12-06 | ||
| US60/922,355 | 2007-04-06 | ||
| US11/741,372 | 2007-04-27 |
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| Publication Number | Publication Date |
|---|---|
| CN101631900A true CN101631900A (en) | 2010-01-20 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200780044560A Pending CN101631900A (en) | 2006-12-06 | 2007-11-21 | System and method of forming a crystal |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104213198A (en) * | 2014-09-09 | 2014-12-17 | 江苏凯新隆石英科技有限公司 | Oval double-layer silica crucible and preparation method thereof |
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2007
- 2007-11-21 CN CN200780044560A patent/CN101631900A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104213198A (en) * | 2014-09-09 | 2014-12-17 | 江苏凯新隆石英科技有限公司 | Oval double-layer silica crucible and preparation method thereof |
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