Patent ID: 12247313

DETAILED DESCRIPTION

Some embodiments of the present disclosure provide a Czochralski single crystal furnace (i.e., single crystal growth furnace) for preparing monocrystalline silicon. The Czochralski single crystal furnace is provided with a first heat-preserving barrel and a second heat-preserving barrel respectively arranged around a reaction chamber. A side wall of the first heat-preserving barrel is provided with a first opening. An axial direction of the first heat-preserving barrel is the same as an axial direction of the second heat-preserving barrel. One of the first heat-preserving barrel and the second heat-preserving barrel is arranged around the other. The Czochralski single crystal furnace has a first operation state and a second operation state, and the Czochralski single crystal furnace may be switched between the first operation state and the second operation state. Herein, in response to the Czochralski single crystal furnace being switched between the first operation state and the second operation state, the first heat-preserving barrel moves relative to the second heat-preserving barrel. In response to the Czochralski single crystal furnace being in the first operation state, a side wall of the second heat-preserving barrel covers the first opening so as to isolate the reaction chamber from outside of the Czochralski single crystal furnace. In response to the Czochralski single crystal furnace being in the second operation state, the second heat-preserving barrel exposes the first opening, so as to enable the reaction chamber to connected to the outside of the Czochralski single crystal furnace through the first opening. Thus, when the reaction chamber of the Czochralski single crystal furnace requires to connected to the outside of the Czochralski single crystal furnace, the first heat-preserving barrel is moved relative to the second heat-preserving barrel to enable the Czochralski single crystal furnace to be in the second operation state, so that the reaction chamber is connected to the outside of the Czochralski single crystal furnace through the first opening. When the reaction chamber inside the Czochralski single crystal furnace requires to isolate from the outside of the Czochralski single crystal furnace, the first heat-preserving barrel is moved relative to the second heat-preserving barrel to enable the Czochralski single crystal furnace to be in in the first operation state, so that the side wall of the second heat-preserving barrel covers the first opening. In this way, the reaction chamber inside the Czochralski single crystal furnace may be quickly connected or isolated from the outside of the Czochralski single crystal furnace. The Czochralski single crystal furnace may further includes a furnace shell, a crucible, a guide barrel and a heater and the like. An insulation quilt is disposed between the first/second heat-preserving barrel and the furnace shell. The insulation quilt may be made of thermal insulation material.

Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings in order to make the objectives, technical solutions and advantages of the present disclosure clearer. However, those skilled in the art may appreciate that, in the various embodiments of the present disclosure, numerous technical details are set forth in order to provide the reader with a better understanding of the present disclosure. However, the technical solutions claimed in the present disclosure may be implemented without these technical details and various changes and modifications based on the following embodiments.

FIG.1shows a Czochralski single crystal furnace for preparing monocrystalline silicon according to a first embodiment of the present disclosure. The Czochralski single crystal furnace includes a reaction chamber110; and a first heat-preserving barrel120and a second heat-preserving barrel130respectively arranged around the reaction chamber110. A side wall of the first heat-preserving barrel120is provided with a first opening121. An axial direction of the first heat-preserving barrel120is the same as an axial direction of the second heat-preserving barrel130. One of the first heat-preserving barrel120and the second heat-preserving barrel130is arranged around the other of the first heat-preserving barrel120and the second heat-preserving barrel130. The Czochralski single crystal furnace has a first operation state and a second operation state, and the Czochralski single crystal furnace may be switched between the first operation state and the second operation state. Herein, in response to the Czochralski single crystal furnace being switched between the first operation state and the second operation state, the first heat-preserving barrel120moves relative to the second heat-preserving barrel130. In response to the Czochralski single crystal furnace being in the first operation state, a side wall of the second heat-preserving barrel130covers the first opening121so as to isolate the reaction chamber110from outside of the Czochralski single crystal furnace. In response to the Czochralski single crystal furnace being in the second operation state, the second heat-preserving barrel130exposes the first opening121, so as to enable the reaction chamber110to connect to the outside of the Czochralski single crystal furnace through the first opening121.

In an embodiment, the second heat-preserving barrel130is arranged around the first heat-preserving barrel120as an example for description. It should be noted that in other embodiments, the first heat-preserving barrel may be arranged around the second heat-preserving barrel, which is not limited in this embodiment.

In an embodiment, a crucible111is provided in the reaction chamber110.

In an embodiment, a material of the first heat-preserving barrel120may be graphite. It should be noted that the material of the first heat-preserving barrel is not limited in this embodiment. For example, in some examples, the material of the first heat-preserving barrel may be a carbon-carbon composite material or a cured felt.

In an embodiment, the material of the second heat-preserving barrel130may be the cured felt. It should be noted that the material of the second heat-preserving barrel is not limited in this embodiment. For example, in some examples, the material of the second heat-preserving barrel may also be the carbon-carbon composite material or the graphite.

The above-mentioned Czochralski single crystal furnace may further include a top cover140and a bottom cover150. The top cover140is located on the tops of the first heat-preserving barrel120and the second heat-preserving barrel130, and is in contact with one of the first heat-preserving barrel120and the second heat-preserving barrel130. The bottom cover150is located on the bottoms of the first heat-preserving barrel120and the second heat-preserving barrel130, and is in contact with the other of the first heat-preserving barrel120and the second heat-preserving barrel130. Herein, the tops of the first heat-preserving barrel120and the second heat-preserving barrel130and the bottoms of the first heat-preserving barrel120and the second heat-preserving barrel130are sequentially arranged along a direction of gravity (i.e., an X direction shown inFIG.1).

This embodiment takes the top cover140being in contact with the second heat-preserving barrel130and the bottom cover150being in contact with the first heat-preserving barrel120as an example for description. In another embodiment, the top cover may be in contact with the first heat-preserving barrel, and in this case, the bottom cover is in contact with the second heat-preserving barrel.

In an embodiment, the materials of the top cover140and the bottom cover150may be graphite. It should be noted that the materials of the top cover and the bottom cover are not limited in this embodiment. For example, in some examples, the materials of the top cover and the bottom cover may be the carbon-carbon composite material or the cured felt, etc.

The Czochralski single crystal furnace may further include a first drive assembly160. The first drive assembly160is configured to drive one of the first heat-preserving barrel120and the second heat-preserving barrel130to move relative to the other along the axial direction of the first heat-preserving barrel120, so that the Czochralski single crystal furnace may be switched between the first operation state and the second operation state. In this way, when the Czochralski single crystal furnace requires to be switched between the first operation state and the second operation state, one of the first heat-preserving barrel120and the second heat-preserving barrel130is driven by the first drive assembly160to move relative to the other along the axial direction of the first heat-preserving barrel120, so that the side wall of the second heat-preserving barrel130covers or exposes the first opening121.

In an embodiment, the first drive assembly160may be four synchronously lifted cylinders161. The four synchronously lifted cylinders161are connected with the bottom of the second heat-preserving barrel130, and then the second heat-preserving barrel130is driven to move relative to the first heat-preserving barrel120in the axial direction of the first heat-preserving barrel120by a lifting or lowering of the four synchronously lifted cylinders161, so that the Czochralski single crystal furnace is switched between the first operation state and the second operation state, and the side wall of the second heat-preserving barrel130covers or exposes the first opening121.

It should be noted that in other embodiments, the number of synchronously lifted cylinders may not be four. In an embodiment, there may be six synchronously lifted cylinders. In another embodiment, there may be eight synchronously lifted cylinders. In addition, the synchronously lifted cylinder may not be connected with the bottom of the second heat-preserving barrel. In an embodiment, the synchronously lifted cylinder may be connected with the bottom of the first heat-preserving barrel, and then the first heat-preserving barrel is driven to move relative to the second heat-preserving barrel along the axial direction of the first heat-preserving barrel by the lifting or lowering of the synchronously lifted cylinder. Alternately, the first drive assembly may not be a synchronously lifted cylinder. In an embodiment, the first drive assembly may be a traction rope. The traction rope is fixed with an end of one of the first heat-preserving barrel and the second heat-preserving barrel, so that the end of the one of the first heat-preserving barrel and the second heat-preserving barrel is pulled by the traction rope to drive the first heat-preserving barrel to move relative to the second heat-preserving barrel along the axial direction of the first heat-preserving barrel.

Further, the first heat-preserving barrel120may include a first upper heat-preserving barrel122, a first middle heat-preserving barrel123and a first lower heat-preserving barrel124which are sequentially arranged along the axial direction of the first heat-preserving barrel120. The first middle heat-preserving barrel123is connected with the first upper heat-preserving barrel122and the first lower heat-preserving barrel124respectively to form the first heat-preserving barrel120together. The first upper heat-preserving barrel122, the first middle heat-preserving barrel123and the first lower heat-preserving barrel124are sequentially arranged along a direction of gravity.

In an embodiment, the first opening121may be disposed at a side wall of the first lower heat-preserving barrel124. The crucible111is located inside the reaction chamber110when the Czochralski single crystal furnace is in use. In this way, after the Czochralski single crystal furnace is used and the crucible111requires to be cooled, the Czochralski single crystal furnace may be in the second operation state, so that the reaction chamber110may be connected with the outside of the Czochralski single crystal furnace through the first opening121, thereby accelerating the cooling speed of the crucible111.

In an embodiment, there may be a plurality of first openings121. In this way, when the second heat-preserving barrel130is moved relative to the axial direction of the first heat-preserving barrel120, the second heat-preserving barrel130may expose a plurality of first openings121, thereby further accelerating the cooling speed of the crucible111. In an example, the plurality of the first openings121may be distributed at equal intervals along a circumferential direction of the first heat-preserving barrel120.

As shown inFIG.2, in an embodiment, there may be six first openings121. Further, the material between two adjacent first openings121of the first heat-preserving barrel120needs to just ensure that it may be used without deformation when the first heat-preserving barrel120is in contact with the bottom cover150. In this way, an opening area of the first opening121may be increased without increasing the size of the first opening121in the axial direction of the first heat-preserving barrel120, thereby further accelerating the cooling speed of the crucible111.

With continued reference toFIG.1, in this embodiment, when the Czochralski single crystal furnace is in a silicon melting stage for preparing the monocrystalline silicon, the Czochralski single crystal furnace is in the first operation state. In this case, the side wall of the second heat-preserving barrel130covers the first opening121so as to isolate the reaction chamber110from the outside of the Czochralski single crystal furnace. When the Czochralski single crystal furnace is in a shutdown and cooling stage for preparing the monocrystalline silicon, the Czochralski single crystal furnace is in the second operation state. In this case, the second heat-preserving barrel130exposes the first opening121, so that the reaction chamber110is connected to the outside of the Czochralski single crystal furnace through the first opening121.

In an embodiment, when the Czochralski single crystal furnace is in a pulling stage for preparing the monocrystalline silicon, the Czochralski single crystal furnace is in the first operation state. In this case, the second heat-preserving barrel130exposes the first opening121, so that the reaction chamber110is connected to the outside of the Czochralski single crystal furnace through the first opening121, and an area of the first opening121exposed by the second heat-preserving barrel130ranges from one tenth to one half of an area of the first opening121.

The second heat-preserving barrel130may include a second upper heat-preserving barrel131, a second middle heat-preserving barrel132and a second lower heat-preserving barrel133which are sequentially arranged along the axial direction of the second heat-preserving barrel130. The second middle heat-preserving barrel132is connected with the second upper heat-preserving barrel131and the second lower heat-preserving barrel133respectively to form the second heat-preserving barrel130. A side wall of the second upper heat-preserving barrel131is provided with a second opening134, and the first heat-preserving barrel120may expose the second opening134, so that the reaction chamber110is connected to the outside of the Czochralski single crystal furnace through the second opening134.

In this way, when the Czochralski single crystal furnace is in use and requires to feed with raw material into the reaction chamber110, the second opening134may be exposed through the first heat-preserving barrel120, so as to facilitate feeding with raw material into the reaction chamber through the second opening134.

In an embodiment, when the Czochralski single crystal furnace is in a pause stage for feeding with raw material for preparing the monocrystalline silicon, the Czochralski single crystal furnace is in the second operation state. In this case, the second heat-preserving barrel130exposes the first opening121so that the reaction chamber110is connected to the outside of the Czochralski single crystal furnace through the first opening121, and the first heat-preserving barrel120exposes the second opening134so that the reaction chamber110is connected to the outside of the Czochralski single crystal furnace through the second opening134and may feed with raw material into the reaction chamber110through the second opening134.

In an embodiment, a lower edge of the first opening121is connected (i.e., flushed) with a lower edge of the first heat-preserving barrel120. A size of the first opening121in the axial direction of the first heat-preserving barrel120ranges from 150 mm to 200 mm (mm: millimeter), that is, the first opening121has a height ranges from 150 mm to 200 mm. The second opening134is a circular feeding port with a diameter ranging from 150 mm to 200 mm. A lifting or lowering stroke of the cylinder161of the first drive assembly160ranges from 180 mm to 200 mm.

In an embodiment, the size of the first opening121in the axial direction of the first heat-preserving barrel120may be 150 mm. The second opening134is a circular feeding port with a diameter of 150 mm. The lifting or lowering stroke of the cylinder161of the first drive assembly160is 180 mm.

A second embodiment of the present disclosure provides a method for preparing monocrystalline silicon, including: a feeding stage of a Czochralski single crystal furnace; a silicon melting stage, a pulling stage of the Czochralski single crystal furnace; and a shutdown and cooling stage of the Czochralski single crystal furnace. With continued reference toFIG.1, in the silicon melting stage, the Czochralski single crystal furnace is in the first operation state, and the side wall of the second heat-preserving barrel130covers the first opening121, thereby isolating the reaction chamber110from the outside of the Czochralski single crystal furnace and enhancing the heat preservation effect of the Czochralski single crystal furnace. The Czochralski single crystal furnace may be the Czochralski single crystal furnace provided in the first embodiment above.

In addition, it should be noted that in the silicon melting stage, the side wall of the first heat-preserving barrel120may cover the second opening134, thereby further enhancing the heat preservation effect of the Czochralski single crystal furnace.

Further,FIG.3shows the Czochralski single crystal furnace is in the pulling stage, and the Czochralski single crystal furnace is in the second operation state. The side wall of the second heat-preserving barrel130exposes the first opening121, and the side wall of the first heat-preserving barrel120covers the second opening134, so that the reaction chamber110may be connected to the outside of the Czochralski single crystal furnace through the first opening121. Herein, an area of the first opening121exposed by the second heat-preserving barrel130ranges from one tenth to one half of an area of the first opening121, thereby reducing an oxygen content in the Czochralski single crystal furnace and further reducing an oxygen content in the monocrystalline silicon.

Furthermore, before the pulling stage of the Czochralski single crystal furnace, the first drive assembly160drives the second heat-preserving barrel130to move along the axial direction of the first heat-preserving barrel120, so that the area of the first opening121exposed by the second heat-preserving barrel130ranges from one tenth to one half of the area of the first opening121.

In an embodiment, a lower edge of the first opening121may be connected (i.e., flushed) with a lower edge of the first heat-preserving barrel120. A size of the first opening121in the axial direction of the first heat-preserving barrel120ranges from 150 mm to 200 mm. A lifting or lowering stroke of the cylinder161of the first drive assembly160ranges from 180 mm to 230 mm.

In an embodiment, the size of the first opening121in the axial direction of the first heat-preserving barrel120is 150 mm. Before the pulling stage of the Czochralski single crystal furnace, the cylinder161of the first drive assembly160is lifted to move the second heat-preserving barrel130by 20 mm in the axial direction of the first heat-preserving barrel120, so that the area of the first opening121exposed by the second heat-preserving barrel130is two fifteenth of the area of the first open121, and the Czochralski single crystal furnace is in the second operation state.

In an example, in the pulling stage of the Czochralski single crystal furnace, when the Czochralski single crystal furnace does not expose the first opening121, the oxygen content in the silicon in the Czochralski single crystal furnace is 14.46 ppma (parts per million atoms). When the second heat-preserving barrel130moves 20 mm along the axial direction of the first heat-preserving barrel120, so that the Czochralski single crystal furnace exposes the first opening121, the oxygen content in the silicon in the Czochralski single crystal furnace is 12.24 ppma. In another example, when the Czochralski single crystal furnace does not expose the first opening121, the oxygen content in the silicon in the Czochralski single crystal furnace is 15.46 ppma. When the second heat-preserving barrel130moves 20 mm along the axial direction of the first heat-preserving barrel120, so that the Czochralski single crystal furnace exposes the first opening121, the oxygen content in the silicon in the Czochralski single crystal furnace is 14.06 ppma. It can be seen that when the second heat-preserving barrel130moves 20 mm along the axial direction of the first heat-preserving barrel120, so that the Czochralski single crystal furnace exposes the first opening121, the oxygen content in the silicon in the Czochralski single crystal furnace is reduced by approximately 11.2% compared with the Czochralski single crystal furnace not exposing the first opening121.

Further,FIG.4shows the Czochralski single crystal furnace is in the feeding stage, or in the shutdown and cooling stage; and the Czochralski single crystal furnace is in the second operation state. The side wall of the second heat-preserving barrel130exposes the first opening121and the side wall of the first heat-preserving barrel120exposes the second opening134, so that the reaction chamber110may be connected to the outside of the Czochralski single crystal furnace through both the first opening121and the second opening134.

Further, before the feeding stage of the Czochralski single crystal furnace, or before the shutdown and cooling stage of the Czochralski single crystal furnace, the first drive assembly160drives the second heat-preserving barrel130to move along the axial direction of the first heat-preserving barrel120, so that the first heat-preserving barrel120exposes the second opening134and the second heat-preserving barrel130exposes the first opening121.

In the feeding stage of the Czochralski single crystal furnace, the reaction chamber110inside the Czochralski single crystal furnace may be fed with raw material through the second opening134. In the shutdown and cooling stage of the Czochralski single crystal furnace, the reaction chamber110may be connected to the outside of the Czochralski single crystal furnace through the first opening121and the second opening134, thereby further accelerating the cooling rate of the Czochralski single crystal furnace.

In an embodiment, the lower edge of the first opening121is connected (i.e., flushed) with the lower edge of the first heat-preserving barrel120. The size of the first opening121in the axial direction of the first heat-preserving barrel120ranges from 150 mm to 200 mm. The second opening134is a circular feeding port with a diameter ranging from 150 mm to 200 mm. The lifting or lowering stroke of the cylinder161of the first drive assembly160ranges from 180 mm to 230 mm.

In an embodiment, the second opening134is a circular feeding port with a diameter of 150 mm. Before the feeding stage of the Czochralski single crystal furnace, or before the shutdown and cooling stage of the Czochralski single crystal furnace, the cylinder161of the first drive assembly160is lifted to move the second heat-preserving barrel130by 180 mm along the axial direction of the first heat-preserving barrel120, so that the first heat-preserving barrel120exposes the second opening134and the second heat-preserving barrel130exposes the first opening121.

FIG.5shows a Czochralski single crystal furnace for preparing monocrystalline silicon according to a third embodiment of the present disclosure. The Czochralski single crystal furnace includes a reaction chamber310, and a first heat-preserving barrel320and a second heat-preserving barrel330respectively arranged around the reaction chamber310. A side wall of the first heat-preserving barrel320is provided with a first opening321. An axial direction of the first heat-preserving barrel320is the same as an axial direction of the second heat-preserving barrel330. One of the first heat-preserving barrel320and the second heat-preserving barrel330is arranged around the other of the first heat-preserving barrel320and the second heat-preserving barrel330. The Czochralski single crystal furnace has a first operation state and a second operation state. The Czochralski single crystal furnace may be switched between the first operation state and the second operation state. Herein, in response to the Czochralski single crystal furnace being switched between the first operation state and the second operation state, the first heat-preserving barrel320moves relative to the second heat-preserving barrel330; in response to the Czochralski single crystal furnace being in the first operation state, a side wall of the second heat-preserving barrel330covers the first opening321so as to isolate the reaction chamber310from an outside of the Czochralski single crystal furnace; and in response to the Czochralski single crystal furnace being in the second operation state, the second heat-preserving barrel330exposes the first opening321, so that the reaction chamber310is connected to the outside of the Czochralski single crystal furnace through the first opening321.

In an embodiment, the second heat-preserving barrel330is arranged around the first heat-preserving barrel320as an example for description. It should be noted that in other embodiments, the first heat-preserving barrel may be arranged around the second heat-preserving barrel. In addition, reference may be made to the above-mentioned first embodiment for the materials of the first heat-preserving barrel320and the second heat-preserving barrel330in this embodiment, which will not be repeated here.

In addition, in an embodiment, a crucible311is provided in the reaction chamber310.

In an embodiment, the Czochralski single crystal furnace provided may further include a top cover340and a bottom cover350. For the functions and connections of the top cover340and the bottom cover350, reference may be made to the above-mentioned first embodiment, which will not be repeated here.

In an embodiment, the top cover340is in contact with the second heat-preserving barrel330, and the bottom cover350is in contact with the first heat-preserving barrel320.

Further, in an embodiment, the side wall of the second heat-preserving barrel330is provided with a third opening331. In response to the Czochralski single crystal furnace being in the second operation state, the third opening331is aligned with the first opening321, so that the reaction chamber310is connected to the outside of the Czochralski single crystal furnace through the first opening321and the third opening331.

Furthermore, in an embodiment, the Czochralski single crystal furnace further includes a second drive assembly360. The first drive assembly360is configured to drive one of the first heat-preserving barrel320and the second heat-preserving barrel330to move relative to the other along the axial direction of the first heat-preserving barrel320, so that the Czochralski single crystal furnace is switched between the first operation state and the second operation state.

In this way, when the Czochralski single crystal furnace requires to be switched between the first operation state and the second operation state, one of the first heat-preserving barrel320and the second heat-preserving barrel330is driven by the second drive assembly360to move relative to the other along the axial direction of the first heat-preserving barrel320, so that the side wall of the second heat-preserving barrel330covers or exposes the first opening121.

It should be noted that in other embodiments, the second drive assembly may not be provided. In an example, the Czochralski single crystal furnace may be provided with a third drive assembly (not shown in the figure). A distance between the first opening and the top cover is the same as a distance between the third opening and the top cover. The third drive assembly is configured to drive one of the first heat-preserving barrel and the second heat-preserving barrel to rotate relative to the other in a circumferential direction of the first heat-preserving barrel. In this way, the third opening may be aligned with the first opening, so that the reaction chamber may be connected to the outside of the Czochralski single crystal furnace through the first opening and the third opening.

In an embodiment, the second drive assembly360may be four synchronously lifted cylinders361. The four synchronously lifted cylinders361are connected with the bottom of the second heat-preserving barrel330, and then the second heat-preserving barrel330is driven to move relative to the first heat-preserving barrel320along the axial direction of the first heat-preserving barrel320by lifting or lowering of the four synchronously lifted cylinders361, so that the Czochralski single crystal furnace is switched between the first operation state and the second operation state, and the side wall of the second heat-preserving barrel330covers or exposes the first opening321.

It should be noted that in other embodiments, the number of synchronously lifted cylinders may not be four. In an embodiment, there may be six synchronously lifted cylinders. In an embodiment, there may be eight synchronously lifted cylinders. In addition, the synchronously lifted cylinder may not be connected with the bottom of the second heat-preserving barrel. In an embodiment, the synchronously lifted cylinder is connected with the bottom of the first heat-preserving barrel, and then the first heat-preserving barrel is driven to move relative to the second heat-preserving barrel along the axial direction of the first heat-preserving barrel by the lifting or lowering of the synchronously lifted cylinder. In addition, the second drive assembly may not be synchronously lifted cylinders. In an embodiment, the second drive assembly may be a traction rope. The traction rope is fixed with an end of one of the first heat-preserving barrel and the second heat-preserving barrel, so that the end of the one of the first heat-preserving barrel and the second heat-preserving barrel is pulled by the traction rope to drive the first heat-preserving barrel to move relative to the second heat-preserving barrel along the axial direction of the first heat-preserving barrel.

In an embodiment, the side wall of the first heat-preserving barrel320or the side wall of the second heat-preserving barrel330is provided with a fourth opening322. One of the first heat-preserving barrel320and the second heat-preserving barrel330may move relative to the other along the axial direction of the first heat-preserving barrel320, so that the reaction chamber310is connected to the outside of the Czochralski single crystal furnace through the fourth opening322.

Further, the first heat-preserving barrel320includes a third upper heat-preserving barrel323, a third middle heat-preserving barrel324and a third lower heat-preserving barrel325which are sequentially arranged along the axial direction of the first heat-preserving barrel320. The third middle heat-preserving barrel324is connected with the third upper heat-preserving barrel323and the third lower heat-preserving barrel325respectively to form the first heat-preserving barrel320together. The second heat-preserving barrel330includes a fourth upper heat-preserving barrel332, a fourth middle heat-preserving barrel333and a fourth lower heat-preserving barrel334which are sequentially arranged along the axial direction of the second heat-preserving barrel330. The fourth middle heat-preserving barrel333is connected with the fourth upper heat-preserving barrel332and the fourth lower heat-preserving barrel334respectively to form the second heat-preserving barrel330together. The first opening321is disposed at a side wall of the third upper heat-preserving barrel323. The third opening331is disposed at a side wall of the fourth upper heat-preserving barrel332or a side wall of the fourth middle heat-preserving barrel333. The fourth opening322is disposed at a side wall of the third lower heat-preserving barrel325.

In an embodiment, the first opening321is disposed at the side wall of the third upper heat-preserving barrel323, the third opening331is disposed at the side wall of the fourth middle heat-preserving barrel333, and the fourth opening322is disposed at the side wall of the third lower heat-preserving barrel325. In an embodiment, the first opening is disposed at the side wall of the third upper heat-preserving barrel, the third opening is disposed at the side wall of the fourth upper heat-preserving barrel, and the fourth opening is disposed at the side wall of the third lower heat-preserving barrel.

In yet another embodiment, the first opening is disposed at the side wall of the third upper heat-preserving barrel or a side wall of the third middle heat-preserving barrel. The third opening is disposed at the side wall of the fourth upper heat-preserving barrel. The fourth opening is disposed at a side wall of the fourth lower heat-preserving barrel. In this case, the drive assembly is configured to drive the first heat-preserving barrel to move along the axial direction of the first heat-preserving barrel, so that the first opening is aligned with the third opening and the first heat-preserving barrel exposes the fourth opening.

Further, in an embodiment, when the Czochralski single crystal furnace is in a silicon melting stage of the monocrystalline silicon preparation, the Czochralski single crystal furnace is in the first operation state. In this case, the side wall of the second heat-preserving barrel330covers the first opening321. In addition, the side wall of the second heat-preserving barrel330may cover the fourth opening322so as to isolate the reaction chamber310from the outside of the Czochralski single crystal furnace. When the Czochralski single crystal furnace is in a pause and feeding stage or a shutdown and cooling stage for preparing the monocrystalline silicon, the Czochralski single crystal furnace is in the second operation state. Herein, when the Czochralski single crystal furnace is in the pause and feeding stage, the temperature in the furnace holds at a high temperature, e.g., greater than 500°. In this case, the second heat-preserving barrel330exposes the first opening321, that is, the third opening331is aligned with the first opening321, so that the reaction chamber310is connected to the outside of the Czochralski single crystal furnace through the first opening321. The second heat-preserving barrel330exposes the fourth opening322, so as to facilitate feeding with raw material into the reaction chamber310through both the third opening331and the first opening321. Further, the reaction chamber310is connected to the outside of the Czochralski single crystal furnace through the fourth opening322, thereby further accelerating the cooling rate of the Czochralski single crystal furnace.

Further, in an embodiment, when the Czochralski single crystal furnace is in a pulling stage for preparing the monocrystalline silicon, the Czochralski single crystal furnace is in the first operation state. In this case, the side wall of the second heat-preserving barrel330exposes the fourth opening322, and the side wall of the second heat-preserving barrel330covers the first opening321, so that the reaction chamber may be connected to the outside of the Czochralski single crystal furnace through the fourth opening322. An area of the fourth opening322exposed by the second heat-preserving barrel330ranges from one tenth to one half of an area of the fourth opening322.

In an embodiment, the first opening321and the third opening331are circular feeding ports with a diameter ranging from 150 mm to 200 mm. A lower edge of the fourth opening322is connected (i.e., flushed) with a lower edge of the first heat-preserving barrel320. A size of the fourth opening322in the axial direction of the first heat-preserving barrel320ranges from 150 mm to 200 mm. A lifting or lowering stroke of the cylinder361of the second drive assembly360ranges from 180 mm 230 mm.

In an embodiment, the first opening321and the third opening331are circular feeding ports with a diameter of 150 mm. The size of the fourth opening322in the axial direction of the first heat-preserving barrel320is 150 mm. The lifting or lowering stroke of the cylinder361of the second drive assembly360is 180 mm.

A fourth embodiment of the present disclosure provides a method for preparing monocrystalline silicon, including: a feeding stage of a Czochralski single crystal furnace; a silicon melting stage, a pulling stage of the Czochralski single crystal furnace, and a shutdown and cooling stage of the Czochralski single crystal furnace. With continued reference toFIG.5, in the silicon melting stage, the Czochralski single crystal furnace is in the first operation state, and the side wall of the second heat-preserving barrel330covers the first opening321, thereby isolating the reaction chamber310from the outside of the Czochralski single crystal furnace. The Czochralski single crystal furnace may be the Czochralski single crystal furnace provided in the third embodiment above.

In addition, it should be noted that in the silicon melting stage, the side wall of the second heat-preserving barrel330may also cover the fourth opening322, thereby further enhancing the heat preservation effect of the Czochralski single crystal furnace.

Further,FIG.6shows the Czochralski single crystal furnace is in the pulling stage, and the Czochralski single crystal furnace is in the first operation state. The side wall of the second heat-preserving barrel330exposes the fourth opening322, and the side wall of the second heat-preserving barrel330covers the first opening321, so that the reaction chamber may be connected to the outside of the Czochralski single crystal furnace through the fourth opening322. An area of the fourth opening322exposed by the second heat-preserving barrel330ranges from one tenth to one half of an area of the fourth opening322.

Furthermore, before the pulling stage of the Czochralski single crystal furnace, the second drive assembly360drives the second heat-preserving barrel330to move along the axial direction of the first heat-preserving barrel320, so that the area of the fourth opening322exposed by the second heat-preserving barrel330ranges from one tenth to one half of the area of the fourth opening322.

In an embodiment, a lower edge of the fourth opening322is connected (i.e., flushed) with a lower edge of the first heat-preserving barrel320. A size of the fourth opening322in the axial direction of the first heat-preserving barrel320ranges from 150 mm to 200 mm. A lifting or lowering stroke of the cylinder361of the second drive assembly360ranges from 180 mm 230 mm.

In an embodiment, the lower edge of the fourth opening322is connected (i.e., flushed) with the lower edge of the first heat-preserving barrel320. The size of the fourth opening322in the axial direction of the first heat-preserving barrel320is 150 mm. Before the pulling stage of the Czochralski single crystal furnace, the cylinder361of the second drive assembly360is lifted to move the second heat-preserving barrel330by 20 mm in the axial direction of the first heat-preserving barrel320, so that the area of the fourth opening322exposed by the second heat-preserving barrel330is two fifteenths of the area of the fourth opening322.

In an example, in the pulling stage of the Czochralski single crystal furnace, when the Czochralski single crystal furnace does not expose the fourth opening322, the oxygen content in the silicon in the Czochralski single crystal furnace is 14.46 ppma. When the second heat-preserving barrel330moves 20 mm along the axial direction of the first heat-preserving barrel320, so that the Czochralski single crystal furnace exposes the fourth opening322, the oxygen content in the silicon in the Czochralski single crystal furnace is 12.24 ppma. In another example, when the Czochralski single crystal furnace does not expose the fourth opening322, the oxygen content in the silicon in the Czochralski single crystal furnace is 15.46 ppma. When the second heat-preserving barrel330moves 20 mm along the axial direction of the first heat-preserving barrel320, so that the Czochralski single crystal furnace exposes the fourth opening322, the oxygen content in the silicon in the Czochralski single crystal furnace is 14.06 ppma. It can be seen that when the second heat-preserving barrel330moves 20 mm along the axial direction of the first heat-preserving barrel320, so as to expose the fourth opening322of the Czochralski single crystal furnace, the oxygen content in the silicon in the Czochralski single crystal furnace is reduced by approximately 11.2% compared with the Czochralski single crystal furnace not exposing the fourth opening322.

FIG.7shows the feeding stage of the Czochralski single crystal furnace, or in the shutdown and cooling stage of the Czochralski single crystal furnace, and the Czochralski single crystal furnace is in the second operation state. The third opening331is aligned with the first opening321, and the side wall of the second heat-preserving barrel330exposes the fourth opening322, so that the reaction chamber310may be connected to the outside of the Czochralski single crystal furnace through the first opening321and the third opening331, and the reaction chamber310may be further connected to the outside of the Czochralski single crystal furnace through the fourth opening322.

Further, before the feeding stage of the Czochralski single crystal furnace, or before the shutdown and cooling stage of the Czochralski single crystal furnace, the second drive assembly360drives the second heat-preserving barrel330to move along the axial direction of the first heat-preserving barrel320, so that the second heat-preserving barrel330exposes the fourth opening322and the first opening321is aligned with the third opening331.

In the feeding stage of the Czochralski single crystal furnace, the reaction chamber310inside the Czochralski single crystal furnace may be fed with raw material through the first opening321and the third opening331. In the shutdown and cooling stage of the Czochralski single crystal furnace, the reaction chamber310may be connected to the outside of the Czochralski single crystal furnace through the first opening321and the third opening331, and the reaction chamber310may also be connected to the outside of the Czochralski single crystal furnace through the fourth opening322, thereby further accelerating the cooling rate of the Czochralski single crystal furnace.

In an embodiment, the first opening321and the third opening331are circular feeding ports with a diameter ranging from 150 mm to 200 mm. The lower edge of the fourth opening322is connected (i.e., flushed) with the lower edge of the first heat-preserving barrel320. The size of the fourth opening322in the axial direction of the first heat-preserving barrel320ranges from 150 mm to 200 mm. The lifting or lowering stroke of the cylinder361of the second drive assembly360ranges from 180 mm to 230 mm.

In an embodiment, the first opening321and the third opening331are circular feeding ports with a diameter of 150 mm. Before the feeding stage of the Czochralski single crystal furnace, or before the Czochralski single crystal furnace shutdown and cooling stage of the Czochralski single crystal furnace, the cylinder361of the second drive assembly360is lifted to move the second heat-preserving barrel330by 180 mm along the axial direction of the first heat-preserving barrel320, so that the second heat-preserving barrel330exposes the fourth opening322, and the first opening321is aligned with the third opening331.

Those skilled in the art shall appreciate that the aforementioned embodiments are specific embodiments for implementing the present disclosure. In practice, however, various changes may be made in the forms and details of the specific embodiments without departing from the scope of the present disclosure. Any person skilled in the art may make their own changes and modifications without departing from the scope of the present disclosure, so the protection scope of the present disclosure shall be subject to the scope defined by the claims.