阅读说明：本技术 氮掺杂剂加料装置、方法及氮掺杂单晶硅棒的制造系统 (Nitrogen-doped agent feeding device and method and manufacturing system of nitrogen-doped silicon single crystal rod ) 是由 徐鹏 衡鹏 李阳 于 2021-09-29 设计创作，主要内容包括：本发明实施例公开了一种氮掺杂剂加料装置、方法及氮掺杂单晶硅棒的制造系统；所述氮掺杂剂加料装置包括：底部设置有开口的承载管,所述承载管用于承载待熔化的氮化硅；环绕于所述承载管外侧的加热装置,所述加热装置用于加热所述待熔化的氮化硅使其完全熔化成氮化硅熔体；设置于所述承载管内部的隔挡装置,所述隔挡装置能够与所述承载管的底部贴合以遮挡所述开口,以防止所述待熔化的氮化硅从所述开口处掉落至所述石英坩埚中；以及,所述隔挡装置能够与所述承载管的底部产生间隙以打开所述开口,以使得所述氮化硅熔体从所述开口处滴落至承载有含硼原子的硅熔体的所述石英坩埚中；升降机构,所述升降机构用于提升或下降所述隔挡装置。(The embodiment of the invention discloses a nitrogen dopant feeding device and method and a manufacturing system of a nitrogen-doped silicon single crystal rod; the nitrogen dopant charging device comprises: the bottom of the bearing tube is provided with an opening, and the bearing tube is used for bearing silicon nitride to be melted; the heating device is arranged around the outer side of the bearing pipe and used for heating the silicon nitride to be melted to be completely melted into a silicon nitride melt; the baffle device is arranged inside the bearing pipe and can be attached to the bottom of the bearing pipe to shield the opening so as to prevent the silicon nitride to be melted from falling into the quartz crucible from the opening; and the baffle device can generate a gap with the bottom of the bearing tube to open the opening, so that the silicon nitride melt drops from the opening into the quartz crucible carrying the boron atom-containing silicon melt; and the lifting mechanism is used for lifting or descending the blocking device.)

1. The nitrogen dopant charging device is characterized in that the nitrogen dopant charging device is arranged right above a quartz crucible, and comprises:

the bottom of the bearing tube is provided with an opening, and the bearing tube is used for bearing silicon nitride to be melted;

the heating device is arranged around the outer side of the bearing pipe and used for heating the silicon nitride to be melted to be completely melted into a silicon nitride melt;

the baffle device is arranged inside the bearing pipe and can be attached to the bottom of the bearing pipe to shield the opening so as to prevent the silicon nitride to be melted from falling into the quartz crucible from the opening; and the baffle device can generate a gap with the bottom of the bearing tube to open the opening, so that the silicon nitride melt drops from the opening into the quartz crucible carrying the boron atom-containing silicon melt;

and the lifting mechanism is used for lifting or descending the blocking device.

2. The nitrogen dopant charging apparatus of claim 1, wherein the carrier tube is made of high density silicon nitride.

3. The nitrogen dopant charging apparatus of claim 1, wherein the heating apparatus is a resistive heater.

4. The nitrogen dopant charging apparatus of claim 1, wherein the baffle means comprises a trace and a baffle ball; wherein, the trace and separate and keep off ball fixed connection.

5. The nitrogen dopant charging apparatus of claim 4, wherein the material of the trace and the spacer ball is high density silicon nitride.

6. The nitrogen dopant charging apparatus of claim 5, wherein the spacer ball has a diameter greater than a diameter of the opening.

7. The nitrogen dopant charging apparatus as claimed in claim 5, wherein the linkage is fixedly connected to the lifting mechanism.

8. A nitrogen dopant charging method that can be applied to the nitrogen dopant charging apparatus described in any one of claims 1 to 7, the nitrogen dopant charging method comprising:

placing a polycrystalline silicon raw material and a boron dopant in a quartz crucible and heating to 1450 ℃ so that the polycrystalline silicon raw material and the boron dopant are melted to form a silicon melt containing boron atoms;

putting a set mass of silicon nitride to be melted into a nitrogen dopant feeding device, and heating to 1800 ℃ by a heating device so as to melt the silicon nitride to be melted to form a silicon nitride melt;

and lifting the blocking device by a lifting mechanism so that the silicon nitride melt drops into the boron atom-containing silicon melt through an opening at the bottom of the bearing tube.

9. A system for producing a nitrogen-doped single crystal silicon rod, the system comprising: the nitrogen dopant charging apparatus of claims 1 to 7, and a crystal pulling apparatus; wherein the content of the first and second substances,

the nitrogen dopant feeding device is used for feeding silicon nitride melt into the boron atom-containing silicon melt in the quartz crucible of the crystal pulling equipment;

the crystal pulling apparatus is used for pulling a single crystal silicon rod by a Czochralski method using a silicon melt containing nitrogen atoms and boron atoms.

Technical Field

The embodiment of the invention relates to the technical field of semiconductors, in particular to a nitrogen dopant feeding device and method and a manufacturing system of a nitrogen-doped monocrystalline silicon rod.

Background

Silicon wafers for producing semiconductor electronic components such as Integrated Circuits (ICs) are mainly produced by slicing a single crystal silicon rod drawn by a Czochralski (Czochralski) method. The Czochralski method includes melting a polycrystalline silicon raw material in a crucible made of quartz to obtain a silicon melt, dipping a seed crystal into the silicon melt, and continuously lifting the seed crystal to move away from the surface of the silicon melt, thereby growing a single crystal silicon rod at a phase interface during the movement.

In the above production process, it is very advantageous to produce a dislocation-free, even twinning-free and polycrystal-free single crystal silicon rod having good mechanical properties and excellent electrical characteristics. One of the methods for producing the silicon single crystal rod is to dope nitrogen atoms in the silicon melt to play a role of pinning dislocations through the nitrogen atoms, which is mainly because the dislocation movement activation energy of the nitrogen-doped silicon single crystal rod is higher than that of the undoped silicon single crystal rod, and further the dislocation slip distance of the nitrogen-doped silicon single crystal rod is short, so that the doping of nitrogen in the silicon single crystal rod can inhibit the generation of dislocations, even twin crystals and polycrystal. At present, as one implementation of nitrogen doping, nitrogen may be doped in a silicon melt in a quartz crucible, and a single crystal silicon rod thus drawn and a silicon wafer cut from the single crystal silicon rod are doped with nitrogen.

Currently, nitrogen doping techniques generally use silicon nitride (Si)₃N₄) As a nitrogen source, a sheet or granular silicon nitride material is put into a polysilicon raw material to realize the addition of nitrogen element, but because the melting temperature of silicon nitride (about 1800 ℃) is higher than the melting point of silicon (1425 ℃), the silicon nitride needs to be heated and stabilized for a period of time at high temperature (more than 1600 ℃) to be completely melted in the silicon melt, and unmelted silicon nitride particles can not exist in the silicon melt when the silicon single crystal rod is pulled, otherwise the silicon nitride particles can enter the silicon single crystal rod to generate dislocation in the silicon single crystal rod, and further the silicon single crystal rod can be further causedScrapping silicon rod products; too high a silicon nitride melt temperature also tends to cause the quartz crucible to soften more, resulting in SiO₂The amount of precipitated oxygen in the process is increased, so that the oxygen content in the process of pulling the silicon single crystal rod is difficult to control, the oxygen content at the top of the silicon single crystal rod is higher, and the product quality of the silicon single crystal rod is influenced.

In addition, especially when the silicon single crystal rod containing nitrogen doping and other dopants such as boron is drawn, the too high temperature of the silicon melt can cause the volatilization amount of the dopant boron to increase, and more seriously, boron atoms and nitrogen atoms form refractory boron nitride at a high temperature exceeding 1600 ℃, and the boron nitride substance is always present in the silicon melt and is easy to cause dislocation, twin crystals and even polycrystal of the silicon single crystal rod, thereby causing the rejection of the silicon single crystal rod product.

Disclosure of Invention

In view of the above, embodiments of the present invention are directed to a nitrogen dopant charging apparatus, a method and a system for manufacturing a nitrogen-doped single crystal silicon rod; can obtain a high-quality nitrogen-doped single crystal silicon rod without dislocation, twin crystal and polycrystal.

The technical scheme of the embodiment of the invention is realized as follows:

in a first aspect, an embodiment of the present invention provides a nitrogen dopant charging apparatus, which is disposed directly above a quartz crucible, and includes:

the bottom of the bearing tube is provided with an opening, and the bearing tube is used for bearing silicon nitride to be melted;

the heating device is arranged around the outer side of the bearing pipe and used for heating the silicon nitride to be melted to be completely melted into a silicon nitride melt;

the baffle device is arranged inside the bearing pipe and can be attached to the bottom of the bearing pipe to shield the opening so as to prevent the silicon nitride to be melted from falling into the quartz crucible from the opening; and the baffle device can generate a gap with the bottom of the bearing tube to open the opening, so that the silicon nitride melt drops from the opening into the quartz crucible carrying the boron atom-containing silicon melt;

and the lifting mechanism is used for lifting or descending the blocking device.

In a second aspect, an embodiment of the present invention provides a nitrogen dopant charging method, which can be applied to the nitrogen dopant charging apparatus described in the first aspect, and the nitrogen dopant charging method includes:

placing a polycrystalline silicon raw material and a boron dopant in a quartz crucible and heating to 1450 ℃ so that the polycrystalline silicon raw material and the boron dopant are melted to form a silicon melt containing boron atoms;

putting a set mass of silicon nitride to be melted into a nitrogen dopant feeding device, and heating to 1800 ℃ by a heating device so as to melt the silicon nitride to be melted to form a silicon nitride melt;

and lifting the blocking device by a lifting mechanism so that the silicon nitride melt drops into the boron atom-containing silicon melt through an opening at the bottom of the bearing tube.

In a third aspect, embodiments of the present invention provide a system for manufacturing a nitrogen-doped single crystal silicon rod, where the system includes: a nitrogen dopant dosing apparatus according to the first aspect, and a crystal pulling apparatus; wherein the content of the first and second substances,

the nitrogen dopant feeding device is used for feeding silicon nitride melt into the boron atom-containing silicon melt in the quartz crucible of the crystal pulling equipment;

the crystal pulling apparatus is used for pulling a single crystal silicon rod by a Czochralski method using a silicon melt containing nitrogen atoms and boron atoms.

The embodiment of the invention provides a nitrogen dopant feeding device and method and a manufacturing system of a nitrogen-doped silicon single crystal rod; in the nitrogen dopant feeding device, before silicon nitride to be melted is put into the bearing tube, the baffle device is descended by the lifting mechanism to be attached to the bottom of the bearing tube so as to shield the opening, so that the silicon nitride to be melted is prevented from falling into the quartz crucible from the opening; after the silicon nitride to be melted is completely melted into the silicon nitride melt, the baffle device is lifted by the lifting mechanism to open the opening, so that the silicon nitride melt drops into the silicon melt containing boron atoms; the nitrogen dopant feeding device can be used for feeding the silicon nitride melt into the silicon melt containing boron atoms, so that the temperature of the silicon melt containing boron atoms in the quartz crucible does not need to exceed 1600 ℃, and under the condition that the melting temperature of the silicon melt containing boron atoms does not exceed 1600 ℃, the nitrogen atoms in the silicon nitride melt can be doped into the silicon melt containing boron atoms, so that boron nitride particles cannot be generated in the whole single crystal silicon rod drawing process, and dislocation, even twin crystal and polycrystalline defects cannot be generated in the finally formed single crystal silicon rod.

Drawings

Fig. 1 is a schematic diagram of an implementation manner of nitrogen doping in a conventional technical solution provided by an embodiment of the present invention;

FIG. 2 is a schematic illustration of boron nitride formation in a silicon melt provided by an embodiment of the present invention;

fig. 3 is a schematic view of a nitrogen dopant loading apparatus according to an embodiment of the present invention;

FIG. 4 is a schematic illustration of nitrogen doping in a silicon melt using a nitrogen dopant charging apparatus in accordance with an embodiment of the present invention;

fig. 5 is a schematic flow chart of a nitrogen dopant loading method according to an embodiment of the present invention;

fig. 6 is a system for manufacturing a silicon single crystal rod doped with nitrogen according to an embodiment of the present invention.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

Referring to fig. 1, one implementation of nitrogen doping in a conventional solution is shown. As shown in fig. 1, polysilicon raw material B1 and other dopants such as boron B2 are contained in a quartz crucible QC together with silicon nitride B3, wherein polysilicon raw material B1 is schematically shown by a region surrounded by a wire frame, boron dopant B2 is schematically shown by a region filled with oblique lines, and silicon nitride B3 is schematically shown by a region filled with black. When the quartz crucible QC was heated to melt the polycrystalline silicon raw material B1, the boron dopant B2, and the silicon nitride B3 contained in the quartz crucible QC, a melt M including silicon atoms, boron atoms, and nitrogen atoms was obtained. However, in the above implementation, since the melting temperature of silicon nitride B3 is about 1800 ℃, and the melting temperatures of polysilicon raw material B1 and boron dopant B2 cannot exceed 1600 ℃, nitrogen atoms from silicon nitride B3 cannot be sufficiently melted, but can be melted only within a certain range around each silicon nitride B3, and thus the distribution of doped nitrogen in the entire melt M is not uniform. Specifically, referring to fig. 1, the obtained melt M can still be roughly divided into three regions according to the difference in nitrogen concentration or nitrogen content as follows: a first melt zone M1 with a low nitrogen content, as schematically shown in fig. 1 by a low-density dot-filled zone, which is located in the quartz crucible QC at a distance from the geometric center of silicon nitride B3; a second melt zone M2 of moderate nitrogen content, as schematically shown in fig. 1 by the region filled with dots of moderate density, which is located in the quartz crucible QC at a moderate distance from the geometric center of silicon nitride B3; a third melt zone M3, which is high in nitrogen content, is located in the quartz crucible QC at a short distance from the geometric center of silicon nitride B3, as schematically shown by the high-density dot-filled zone in fig. 1.

The shape of the silicon nitride B3 is not limited to a sheet shape, and may be a granular shape.

On the other hand, if the melting temperature of the polysilicon raw material B1 and the boron dopant B2 is increased to 1600 ℃ or higher in order to completely melt the silicon nitride B3, boron nitride particles B4 are formed in the melt M, as shown in the black circles in fig. 2. The boron nitride particles B4 are infusible substances and always exist in the melt M, so that the defects of dislocation, twin crystals and even polycrystal are easily generated in the single crystal silicon rod, and the single crystal silicon rod product is scrapped in serious cases.

Based on the above explanation, in order to obtain a dislocation-free, twin-crystal-free and polycrystalline defect-free single crystal silicon rod containing nitrogen atoms and boron atoms, embodiments of the present invention are expected to improve the feeding manner of silicon nitride B3 on the basis of being able to obtain a boron atom-containing silicon melt M'. Fig. 3 is a schematic view of a nitrogen dopant charging apparatus 30 according to an embodiment of the present invention, wherein the nitrogen dopant charging apparatus 30 is disposed directly above a quartz crucible QC, and the nitrogen dopant charging apparatus 30 may specifically include:

the bottom of the bearing pipe 301 is provided with an opening 3011, and the bearing pipe 301 is used for bearing silicon nitride B3 to be melted;

a heating device 302 surrounding the outer side of the carrying tube, wherein the heating device 302 is used for heating the silicon nitride B3 to be melted to be completely melted into a silicon nitride melt M';

a baffle 303 disposed inside the carrier tube, the baffle 303 being capable of engaging with the bottom of the carrier tube 301 to block the opening 3011 to prevent the silicon nitride B3 to be melted from falling from the opening 3011 into the quartz crucible QC; and the blocking device 303 can generate a gap with the bottom of the carrier tube 301 to open the opening 3011, so that the silicon nitride melt M ″ drops from the opening 3011 to the quartz crucible QC of the silicon melt M' carrying boron atoms;

a lifting mechanism 304, wherein the lifting mechanism 304 is used for lifting or lowering the blocking device 303.

It is to be understood that with the nitrogen dopant charging apparatus 30 according to the present invention, as shown in fig. 3, before the silicon nitride B3 to be melted is placed on the nitrogen dopant charging apparatus 30, the stopper is first lowered by the elevating mechanism 304 to abut against the bottom of the carrier tube 301 to block the opening 3011, so as to prevent the silicon nitride B3 to be melted from falling from the opening 3011 into the quartz crucible QC; as shown in fig. 4, after the silicon nitride B3 to be melted is completely melted into silicon nitride melt M ", the stopper 303 is lifted by the lifting mechanism 304 to open the opening 3011, so that the silicon nitride melt M" drops into the silicon melt M' containing boron atoms.

The nitrogen dopant feeding device 30 can be used to feed the silicon nitride melt M ″ into the silicon melt M 'containing boron atoms, so that the temperature of the silicon melt M' containing boron atoms in the quartz crucible QC does not need to exceed 1600 ℃, and the nitrogen atoms in the silicon nitride melt M ″ can be doped into the silicon melt M 'containing boron atoms when the melting temperature of the silicon melt M' containing boron atoms does not exceed 1600 ℃, so that boron nitride particles B4 are not generated during the whole pulling process of the single crystal silicon rod, and dislocations, even twin crystals and polycrystalline defects are not generated in the finally formed single crystal silicon rod.

Further, it is understood that the method of adding the silicon nitride melt M 'to the boron atom-containing silicon melt M' does not cause the final temperature in the quartz crucible QC to be excessively high and thus does not easily cause the quartz crucible QC to be softened more so as to cause SiO₂The precipitated oxygen is increased, so that the phenomenon that the oxygen content is difficult to control in the process of pulling the silicon single crystal rod can not occur.

It should be noted that the quality of the silicon nitride B3 to be melted placed in the carrier tube 301 is predetermined to ensure that the nitrogen content in the finally drawn single crystal silicon rod meets the product requirement.

For the nitrogen dopant dosing apparatus 30 shown in fig. 3, in some examples, the material of the carrier tube 301 is high density silicon nitride. It can be understood that when the silicon nitride B3 to be melted is heated and melted, the overall temperature inside the entire nitrogen dopant charging apparatus 30 is raised to 1800 ℃, so that the carrier tube 301 needs to be made of a high temperature resistant material to ensure the service life of the carrier tube 301; on the other hand, in order to ensure that the silicon nitride B3 to be melted does not introduce new impurities during the heating melting process, the material of the carrier tube 301 is preferably a high-density silicon nitride material.

For the nitrogen dopant dosing device 30 shown in fig. 3, in some examples, it is preferred that the heating device be a resistive heater. This is mainly because the melting temperature of silicon nitride B3 to be melted can be accurately controlled when carrier tube 301 is heated by the resistance heater; next, the carrier tube 301 is heated uniformly by the resistance heater, so that the silicon nitride B3 to be melted can be uniformly melted. Of course, it can be understood that the resistance heater has high thermal efficiency, and the heating cost can be effectively saved because the heat loss is small when the carrier tube 301 is heated.

For the nitrogen dopant dosing device 30 shown in fig. 3, in some examples, it is preferred that the baffle device 303 comprises a trace 3031 and a baffle ball 3032; the linkage rod 3031 and the blocking ball 3032 are fixedly connected. It should be noted that the linking rod 3031 and the blocking ball 3032 may be fixedly connected together by welding, or the linking rod 3031 and the blocking ball 3032 may be manufactured as an integral structure in a specific implementation process.

For the above example, in some specific embodiments, it is preferable that the material of the coupling rod 3031 and the blocking ball 3032 is high-density silicon nitride. It can be understood that, during the heating and melting process of the silicon nitride B3 to be melted, the linkage rod 3031 and the baffle ball 3032 are always located inside the carrier tube 301, and therefore, in order to ensure the service life of the linkage rod 3031 and the baffle ball 3032 and not introduce new impurities, the material of the linkage rod 3031 and the baffle ball 3032 is preferably high-temperature-resistant high-density silicon nitride material.

For the above example, in some specific embodiments, it is preferable that the diameter of the blocking ball 3032 is larger than the diameter of the opening 3011. It will be appreciated that in the practice of the invention, to prevent silicon nitride B3 to be melted from falling through opening 3011, the diameter of spacer ball 3032 is therefore greater than the diameter of opening 3011 to ensure that when spacer ball 3032 is lowered into engagement with the bottom of carrier tube 301, it completely blocks opening 3011, even when silicon nitride B3 to be melted is in the form of particles, silicon nitride B3 in the form of particles will not fall through opening 3011.

For the above example, in some specific embodiments, the linkage 3031 is fixedly connected to the lifting mechanism 304. It is understood that, in order to facilitate the ascending or descending of the isolation ball 3032, in the embodiment of the present invention, the linkage 3031 is fixedly connected to the ascending and descending mechanism 304, so as to control the ascending or descending of the isolation ball 3032 and thus the blocking or opening of the opening 3011 by the ascending and descending mechanism 304.

Referring to fig. 5, an embodiment of the present invention further provides a nitrogen dopant charging method, which can be applied to the nitrogen dopant charging apparatus 30 described above, and the nitrogen dopant charging method includes:

s501, placing polycrystalline silicon raw material B1 and boron dopant B2 in a quartz crucible QC and heating to 1450 ℃ so that the polycrystalline silicon raw material B1 and the boron dopant B2 are melted to form a boron atom-containing silicon melt M';

s502, putting a set mass of silicon nitride B3 to be melted into the nitrogen dopant feeding device 30, and heating the silicon nitride B3 to 1800 ℃ by the heating device 302 to melt the silicon nitride B3 to form a silicon nitride melt M ";

s503, lifting the blocking device 303 by the lifting mechanism 304, so that the silicon nitride melt M 'drops into the boron atom-containing silicon melt M' through the opening at the bottom of the bearing tube.

It is understood that after the silicon nitride melt M 'is dropped completely to the boron atom-containing silicon melt M', the pulling of the single crystal silicon rod can be started after the silicon melt containing nitrogen atoms and boron atoms in the quartz crucible QC is stabilized.

Referring to fig. 6, an embodiment of the present invention further provides a manufacturing system 50 for a nitrogen-doped single crystal silicon rod, where the manufacturing system 50 specifically includes: a nitrogen dopant dosing apparatus 30 as described above, and a crystal pulling apparatus 40; wherein the content of the first and second substances,

the nitrogen dopant feeding device 30 is used to incorporate a silicon nitride melt M "into a boron atom containing silicon melt M' within a quartz crucible QC in the crystal pulling apparatus 40;

the crystal pulling apparatus 40 is used for pulling a single crystal silicon rod using a Czochralski method using a silicon melt containing nitrogen atoms and boron atoms.

It should be noted that the crystal pulling apparatus 1 described above may be a device in a crystal pulling furnace, such as a guide cylinder, a silicon single crystal rod pulling device, and the like, associated with pulling a silicon single crystal rod, and a device in a crystal pulling furnace, such as a quartz crucible QC, a graphite heater, and the like, associated with melting polycrystalline silicon feedstock B1 and boron dopant B2, and therefore the nitrogen dopant feeding device 30 and the crystal pulling apparatus 1 of the present invention may be implemented in the same conventional crystal pulling furnace.

It should be noted that: the technical schemes described in the embodiments of the present invention can be combined arbitrarily without conflict.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.