TWI852339B - Crucible device, single crystal furnace device and working method thereof - Google Patents

Abstract

The invention provides a crucible device, a single crystal furnace device and a working method thereof, belonging to the field of semiconductor manufacturing technology. The crucible device comprises: a graphite crucible; a quartz crucible sleeved in the graphite crucible; and a crucible heat insulation structure located outside the graphite crucible and covering the lower half of the graphite crucible. The single crystal furnace device comprises: a furnace body; a heater is arranged in the furnace body, the heater is fixed to the bottom of the furnace body through electrode bolts, and is connected to the heating electrode at the bottom of the furnace body; a crucible shaft is arranged in the center of the heater, a crucible tray is arranged at the upper end of the crucible shaft, the lower end of the crucible shaft passes through the bottom of the furnace body, and the crucible tray carries the crucible device; a control unit is respectively connected to the crucible shaft and the crystal rod pulling device, and is used to control the rotation direction and speed of the crucible shaft and the crystal rod respectively.

Description

Crucible device, single crystal furnace device and working method thereof

The present invention belongs to the field of semiconductor manufacturing technology, and in particular relates to a crucible device, a single crystal furnace device and a working method thereof.

As a semiconductor material, single crystal silicon is generally used to manufacture integrated circuits and other electronic components. Currently, there are two single crystal silicon growth technologies: zone melting method and Czochralski method, of which Czochralski method is the most commonly used method. When manufacturing single crystal silicon by Czochralski method, polycrystalline material is placed in a quartz crucible, heated to high temperature to melt it, and then the seed crystal is lowered from the top into the molten polycrystalline silicon. By controlling the temperature of the liquid surface, the molten polycrystalline silicon is re-crystallized around the seed crystal to form neatly arranged single crystal silicon rods.

With the continuous improvement of the quality of semiconductor silicon wafers, there are higher control requirements for the crystal defects of the crystal rods in the crystal pulling process. There are two main factors that affect the crystal defects. The first is the crystal pulling process parameters. Using optimized process parameters to pull crystals can produce better quality crystal rods; the second is the structure and performance of the thermal field. Its quality is a prerequisite for the quality of the crystal rod. The thermal field is a crucial component of the crystal pulling furnace. Due to the strict requirements on the crystal pulling environment of the crystal pulling furnace, the quality and material requirements of the thermal field are extremely high. It must not only be resistant to high temperatures and have good thermal stability, but also have high purity.

As one of the most important components in the thermal field, the crucible is generally divided into two parts. The outer part is usually a graphite crucible, which supports the quartz crucible and transfers heat. The inner quartz crucible is used to hold the silicon solution. At the same time, the oxygen in the crystal rod is decomposed from the quartz crucible. Usually, the amount of oxygen precipitation at the R-shaped arc surface is the largest. The oxygen content at the head of the crystal rod is very high. At the tail of the crystal rod, the contact area between the silicon solution and the R part of the quartz crucible is reduced due to the reduction of the solution, resulting in too low oxygen content at the tail of the crystal rod.

In order to solve the above technical problems, the present invention provides a crucible device, a single crystal furnace device and a working method thereof, which can increase the uniformity of oxygen in the crystal rod and improve the problem of low oxygen content at the tail of the crystal rod.

In order to achieve the above-mentioned purpose, the technical solution adopted in the embodiment of the present invention is: A crucible device, comprising: A graphite crucible; A quartz crucible sleeved in the graphite crucible; A crucible insulation structure located outside the graphite crucible and covering the lower half of the graphite crucible.

In some embodiments, the crucible insulation structure includes: A graphite bottom cylinder; A graphite outer cylinder supported on the graphite bottom cylinder; A graphite inner cylinder sleeved in the graphite outer cylinder.

In some embodiments, the crucible insulation structure further includes: Insulating felt located between the graphite outer cylinder and the graphite inner cylinder. In some embodiments, the crucible device further includes: A stirring propeller disposed at the bottom of the quartz crucible.

In some embodiments, the propeller blade of the stirring propeller has a blade span of 30 mm to 40 mm.

In some embodiments, the height of the propeller blade of the stirring propeller is 40mm-60mm.

The embodiment of the present invention also provides a single crystal furnace device, comprising: A furnace body; A heater is arranged in the furnace body, the heater is fixed to the bottom of the furnace body through electrode bolts, and is connected to the heating electrode at the bottom of the furnace body; A crucible shaft is arranged in the center of the heater, a crucible tray is arranged at the upper end of the crucible shaft, the lower end of the crucible shaft passes through the bottom of the furnace body, and the crucible tray carries the crucible device as described above; A control unit is connected to the crucible shaft and the crystal rod pulling device respectively, and is used to control the rotation direction and speed of the crucible shaft and the crystal rod pulling device respectively.

In some embodiments, the control unit is also connected to the stirring propeller to control the rotation direction and speed of the stirring propeller.

The embodiment of the present invention also provides a working method of a single crystal furnace device, which is applied to the single crystal furnace device as described above, and the working method includes: During the crystal pulling process, the control unit controls the rotation direction of the crucible shaft to be the same as the rotation direction of the crystal rod of the pulling device, and the rotation speed is the same.

In some embodiments, the working method further includes: During the crystal pulling process, the control unit controls the rotation direction of the stirring propeller to be opposite to the rotation direction of the crucible shaft.

The advantages of the present invention are: The crucible device is conducive to blocking the radiation of the heater heat to the crucible R part, reducing the precipitation of oxygen in the R part of the quartz crucible during the crystal pulling process. At the same time, during the crystal pulling process, the crucible rotates in the same direction and at the same speed as the crystal rod, reducing the relative convection between the melt and the crystal rod, thereby reducing the oxygen content immersed in the crystal rod.

In order to avoid the solution at the bottom of the crucible from being overcooled and solidified, especially the oxygen content at the tail of the crystal rod is too low (the contact area between the silicon solution and the R part of the crucible is reduced, which greatly reduces the precipitation of oxygen content), a bottom stirring screw is set to increase the forced convection of the melt, so that the oxygen precipitated from the inner surface of the quartz crucible (mainly the oxygen at the R-shaped arc of the quartz crucible) is evenly immersed in the crystal rod, increasing the uniformity of oxygen in the crystal rod axis.

In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the embodiments of the present invention will be clearly and completely described below in conjunction with the attached drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by those with ordinary knowledge in the field are within the scope of protection of the present invention.

In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are based on the directions or positional relationships shown in the attached drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or components referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

The present invention provides a crucible device, a single crystal furnace device and a working method thereof, which can increase the uniformity of oxygen in a crystal rod and improve the problem of low oxygen content at the tail of the crystal rod.

The present invention provides a crucible device, as shown in FIG1 and FIG2, comprising: A graphite crucible 2; A quartz crucible 1 sleeved in the graphite crucible 2; A crucible insulation structure located outside the graphite crucible 2 and covering the lower half of the graphite crucible 2.

In this embodiment, a crucible insulation structure covering the lower half of the graphite crucible 2 is provided on the outer side of the graphite crucible 2. The crucible insulation structure can effectively prevent the heat of the heater from radiating to the R portion of the graphite crucible 2, thereby reducing the precipitation of oxygen in the R portion and reducing the natural convection near the R portion, thereby improving the uniformity of oxygen in the crystal rod and improving the problem of low oxygen content at the tail of the crystal rod.

In some embodiments, as shown in FIG. 1 and FIG. 2 , the crucible heat insulation structure includes: A graphite bottom cylinder 7; A graphite outer cylinder 5 supported on the graphite bottom cylinder 7; A graphite inner cylinder 4 sleeved in the graphite outer cylinder 5.

The crucible insulation structure adopts a three-layer graphite structure, which can effectively prevent the heat of the heater from radiating to the R part of the graphite crucible 2, thereby reducing the precipitation of oxygen in the R part. In addition, because graphite has a high thermal conductivity at high temperature, it can well transfer the heat of the heater to the quartz crucible 1 evenly, and the quartz crucible 1 then transfers the heat to the silicon solution to maintain a constant liquid surface temperature, which is conducive to the stable progress of the crystal pulling solidification process.

As shown in FIG. 3 , the graphite bottom cylinder 7 is in a disc shape, which can provide good support for the graphite outer cylinder 5 and the graphite inner cylinder 4 .

As shown in FIG. 4 , the shape of the graphite inner tube 4 matches the shape of the lower half of the graphite crucible 2 , and can fit well with the lower half of the graphite crucible 2 , preventing the heat of the heater from radiating to the R portion of the graphite crucible 2 .

As shown in FIG5 , the graphite outer cylinder 5 is cylindrical, and the shape of the bottom surface of the graphite outer cylinder 5 can match the upper surface of the graphite bottom cylinder 7. As shown in FIG3 , the upper surface of the graphite bottom cylinder 7 is provided with a circle of grooves, and the bottom surface of the graphite outer cylinder 5 can be provided with a circle of protrusions matching the circle of grooves, so that the graphite outer cylinder 5 can be stably fixed on the graphite bottom cylinder 7.

In some embodiments, as shown in FIG. 1 and FIG. 2 , the crucible insulation structure further includes: Insulating felt 6 located between the graphite outer cylinder 5 and the graphite inner cylinder 4. The insulating felt 6 has a good thermal insulation coefficient and can effectively prevent the heat of the heater from radiating to the R portion of the graphite crucible 2, thereby reducing the precipitation of oxygen in the R portion.

As shown in Figure 6, the shape of the outer surface of the insulating felt 6 can match the shape of the inner surface of the graphite outer cylinder 5, and the shape of the inner surface of the insulating felt 6 can match the shape of the outer surface of the graphite inner cylinder 4, so that the insulating felt 6 can fit tightly with the graphite inner cylinder 4 and the graphite outer cylinder 5 respectively.

In some embodiments, as shown in FIG. 2 , in order to prevent the silicon solution at the bottom of the quartz crucible 1 from being overcooled and solidified, especially the oxygen content at the tail of the crystal rod is too low (the contact area between the silicon solution and the R part of the crucible is reduced, which greatly reduces the precipitation of oxygen content), the crucible device also includes: A stirring propeller 3 arranged at the bottom of the quartz crucible 1, through which the forced convection of the melt can be increased, so that the oxygen precipitated on the inner surface of the quartz crucible 1 (mainly the oxygen at the R-shaped arc of the quartz crucible 1) is uniformly immersed in the crystal rod, thereby increasing the uniformity of oxygen in the crystal rod.

In some embodiments, the propeller blade of the stirring propeller 3 has a blade span of 30-40 mm. When the propeller blade of the stirring propeller 3 has a blade span of 30-40 mm, the silicon solution can be effectively stirred.

In some embodiments, the height of the propeller blades of the stirring propeller 3 is 40-60 mm. When the height of the propeller blades of the stirring propeller 3 is 40-60 mm, the silicon solution can be effectively stirred.

This embodiment can produce N-type low-oxygen products with uniform axial oxygen content (4.5 ppma±0.5 ppma).

The embodiment of the present invention also provides a single crystal furnace device, as shown in FIG2, comprising: A furnace body; A heater is arranged in the furnace body, the heater is fixed to the bottom of the furnace body by electrode bolts, and is connected to the heating electrode at the bottom of the furnace body; A crucible shaft 9 is arranged in the center of the heater, a crucible tray 8 is arranged at the upper end of the crucible shaft 9, the lower end of the crucible shaft 9 passes through the bottom of the furnace body, and the crucible tray 8 carries the crucible device as described above; A control unit is connected to the crucible shaft 9 and the crystal rod pulling device respectively, and is used to control the rotation direction and speed of the crucible shaft 9 and the crystal rod pulling device respectively.

In this embodiment, a crucible insulation structure covering the lower half of the graphite crucible is provided on the outer side of the graphite crucible. The crucible insulation structure can effectively block the heat of the heater from radiating to the R portion of the graphite crucible, thereby reducing the precipitation of oxygen in the R portion and reducing the natural convection near the R portion, thereby improving the uniformity of oxygen in the crystal rod and improving the problem of low oxygen content at the tail of the crystal rod.

In this embodiment, the control unit can control the rotation direction and speed of the crucible shaft 9 and the crystal rod pulling device. In this way, during the crystal pulling process, the control unit can control the rotation direction of the crucible device and the rotation direction of the crystal rod to be the same direction and the same speed, which can reduce the relative convection between the melt and the crystal rod, thereby reducing the oxygen content immersed in the crystal rod.

In some embodiments, the control unit is also connected to the stirring propeller to control the rotation direction and speed of the stirring propeller. The control unit can drive the stirring propeller 3 to rotate, so that during the crystal pulling process, the control unit can control the rotation direction of the stirring propeller 3 to be opposite to the rotation direction of the crucible shaft 9, which can increase the forced convection of the melt, so that the oxygen precipitated from the inner surface of the quartz crucible (mainly the oxygen at the R-shaped arc of the quartz crucible) is uniformly immersed in the crystal rod, thereby increasing the uniformity of oxygen in the crystal rod.

The embodiment of the present invention also provides a working method of a single crystal furnace device, which is applied to the single crystal furnace device as described above, and the working method includes: During the crystal pulling process, the control unit controls the rotation direction of the crucible shaft to be the same as the rotation direction of the crystal rod pulling device, and the rotation speed is the same.

In this embodiment, the control unit can control the rotation direction and speed of the crucible shaft and the crystal rod pulling device, so that during the crystal pulling process, the control unit can control the rotation direction of the crucible device and the rotation direction of the crystal rod to be the same direction and the same speed, which can reduce the relative convection between the melt and the crystal rod, thereby reducing the oxygen content immersed in the crystal rod.

In some embodiments, the working method further includes: During the crystal pulling process, the control unit controls the rotation direction of the stirring propeller to be opposite to the rotation direction of the crucible shaft.

The control unit can drive the stirring screw 3 to rotate, so that during the crystal pulling process, the control unit can control the rotation direction of the stirring screw to be opposite to the rotation direction of the crucible shaft 9, so as to increase the forced convection of the melt, so that the oxygen precipitated from the inner surface of the quartz crucible (mainly the oxygen at the R-shaped arc of the quartz crucible) is evenly immersed in the crystal rod, thereby increasing the uniformity of oxygen in the crystal rod.

It should be noted that each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the embodiments, since they are basically similar to the product embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of the product embodiments.

In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person of ordinary skill in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the patent application.

1: Quartz crucible 2: Graphite crucible 3: Stirring propeller 4: Graphite inner cylinder 5: Graphite outer cylinder 6: Insulation felt 7: Graphite bottom cylinder 8: Crucible tray 9: Crucible shaft

Figure 1 is a schematic diagram of the structure of the crucible device of the embodiment of the present invention; Figure 2 is a schematic diagram of the structure of the single crystal furnace device of the embodiment of the present invention; Figure 3 is a schematic diagram of the structure of the graphite bottom cylinder of the embodiment of the present invention; Figure 4 is a schematic diagram of the structure of the graphite inner cylinder of the embodiment of the present invention; Figure 5 is a schematic diagram of the structure of the graphite outer cylinder of the embodiment of the present invention; Figure 6 is a schematic diagram of the structure of the heat insulating felt of the embodiment of the present invention.

1: Quartz crucible

2: Graphite crucible

3: Stirring propeller

4: Graphite inner cylinder

5: Graphite outer cylinder

6: Insulation felt

7: Graphite bottom tube

8: Crucible tray

9: Crucible shaft

Claims (9)

A crucible device includes: a graphite crucible; a quartz crucible sleeved in the graphite crucible; a crucible heat insulation structure located outside the graphite crucible and covering the lower half of the graphite crucible; wherein the crucible heat insulation structure includes: a graphite bottom cylinder; a graphite outer cylinder supported on the graphite bottom cylinder; a graphite inner cylinder sleeved in the graphite outer cylinder; wherein the shape of the graphite inner cylinder matches the shape of the lower half of the graphite crucible; and the shape of the bottom surface of the graphite outer cylinder matches the upper surface of the graphite bottom cylinder. The crucible device as described in claim 1, wherein the crucible insulation structure further comprises: an insulating felt located between the graphite outer cylinder and the graphite inner cylinder. The crucible device as described in claim 1 further comprises: a stirring propeller disposed at the bottom of the quartz crucible. The crucible device as described in claim 3, wherein the propeller blade of the stirring propeller has a blade span of 30-40 mm. The crucible device as described in claim 3, wherein the propeller blade of the stirring propeller has a height of 40-60 mm. A single crystal furnace device comprises: a furnace body; a heater is arranged in the furnace body, the heater is fixed to the bottom of the furnace body through electrode bolts and connected to the heating electrode at the bottom of the furnace body; a crucible shaft is arranged in the center of the heater, a crucible tray is arranged at the upper end of the crucible shaft, the lower end of the crucible shaft passes through the bottom of the furnace body, and the crucible tray carries the crucible device as described in any one of claims 1 to 5; a control unit is connected to the crucible shaft and the crystal rod pulling device respectively, and is used to control the rotation direction and speed of the crucible shaft and the crystal rod pulling device respectively. The single crystal furnace device as described in claim 6 includes the crucible device as described in claim 3, and the control unit is also connected to the stirring propeller to control the rotation direction and speed of the stirring propeller. A working method of a single crystal furnace device is applied to the single crystal furnace device as described in claim 6 or 7, and the working method includes: during the crystal pulling process, the control unit controls the rotation direction of the crucible shaft to be the same as the rotation direction of the crystal rod pulling device, and the rotation speed is the same. The working method of the single crystal furnace device as described in claim 8 is applied to the single crystal furnace device as described in claim 7, and the working method further includes: during the crystal pulling process, the control unit controls the rotation direction of the stirring propeller to be opposite to the rotation direction of the crucible shaft.