阅读说明：本技术 一种用于晶体生长的液面检测装置及晶体生长装置 (Liquid level detection device for crystal growth and crystal growth device ) 是由 赵旭良 于 2020-12-23 设计创作，主要内容包括：本发明公开了一种用于晶体生长的液面检测装置及晶体生长装置,所述液面检测装置包括：炉体,所述炉体内设置有坩埚,所述坩埚内包括熔体；导流筒,所述导流筒位于所述熔体的上方,所述导流筒的底部设置有定位销,所述定位销的至少一部分由不透明材料填充；相机,用于获取所述定位销与所述定位销在所述熔体液面上的倒影的图像；图像处理器,基于所述定位销与所述定位销在所述熔体液面上的倒影的图像计算所述定位销与所述熔体液面之间的距离。根据本发明提供的用于晶体生长的液面检测装置,定位销的至少一部分由不透明材料填充,以利用相机获取设置在导流筒底部的定位销与所述定位销在熔体液面上的倒影的清晰图像,以准确计算所述定位销与所述熔体液面之间的距离,操作简便、成本低。(The invention discloses a liquid level detection device for crystal growth and a crystal growth device, wherein the liquid level detection device comprises: the crucible furnace comprises a furnace body, wherein a crucible is arranged in the furnace body, and a melt is contained in the crucible; the guide cylinder is positioned above the melt, a positioning pin is arranged at the bottom of the guide cylinder, and at least one part of the positioning pin is filled with an opaque material; the camera is used for acquiring images of the positioning pin and the reflection of the positioning pin on the liquid level of the melt; an image processor that calculates a distance between the locating pin and the melt level based on an image of a reflection of the locating pin and the locating pin on the melt level. According to the liquid level detection device for crystal growth, at least one part of the positioning pin is filled with the opaque material, so that a camera is used for acquiring a clear image of the positioning pin arranged at the bottom of the guide cylinder and a reflection image of the positioning pin on the liquid level of the melt, the distance between the positioning pin and the liquid level of the melt is accurately calculated, and the liquid level detection device is simple and convenient to operate and low in cost.)

1. A liquid level detection apparatus for crystal growth, comprising:

the crucible furnace comprises a furnace body, wherein a crucible is arranged in the furnace body, and a melt is contained in the crucible;

the guide cylinder is positioned above the melt, a positioning pin is arranged at the bottom of the guide cylinder, and at least one part of the positioning pin is filled with an opaque material;

the camera is used for acquiring images of the positioning pin and the reflection of the positioning pin on the liquid level of the melt;

an image processor that calculates a distance between the locating pin and the melt level based on an image of a reflection of the locating pin and the locating pin on the melt level.

2. The fluid level sensing device of claim 1, wherein the alignment pin comprises a housing portion and a fill portion.

3. The fluid level sensing device of claim 2, wherein the housing portion comprises a high temperature resistant material.

4. The fluid level sensing device of claim 3, wherein the housing portion comprises quartz.

5. The fluid level sensing device of claim 4, wherein the housing portion comprises high transparency quartz with low impurity content.

6. The fluid level sensing device of claim 2, wherein the filling portion comprises an opaque material.

7. The liquid level detecting device according to claim 6, wherein the filling part comprises graphite or silicon.

8. The liquid level detecting device according to claim 1, wherein an observation window is provided on the furnace body, and the camera is provided outside the furnace body, and liquid level detection is performed through the observation window.

9. A crystal growth apparatus comprising the liquid level detection apparatus according to any one of claims 1 to 8.

Technical Field

The invention relates to the technical field of crystal growth, in particular to a liquid level detection device for crystal growth and a crystal growth device.

Background

With the rapid development of the Integrated Circuit (IC) industry, device manufacturers have placed more stringent requirements on IC-grade silicon single crystal materials, which are the substrate materials necessary for device fabrication. The Czochralski method is the most important method for growing single crystal from melt in the prior art, and is characterized by that the raw materials for forming crystal are placed in a quartz crucible, heated and melted, then the crystal is pulled up by inoculating seed crystal on the surface of melt, under the controlled condition, the seed crystal and melt are continuously rearranged in atom or molecule on the interface, and then the crystal is gradually solidified with the cooling down so as to grow out the crystal.

In the process of crystal growth, the distance between the liquid level of the melt and the guide cylinder needs to be measured, and the accurate measurement of the distance is difficult to realize through the existing technical means.

Therefore, it is necessary to provide a new crystal growth apparatus to solve the above problems.

Disclosure of Invention

In this summary, concepts in a simplified form are introduced that are further described in the detailed description. This summary of the invention is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

The invention provides a liquid level detection device for crystal growth, which comprises:

the crucible furnace comprises a furnace body, wherein a crucible is arranged in the furnace body, and a melt is contained in the crucible;

the guide cylinder is positioned above the melt, a positioning pin is arranged at the bottom of the guide cylinder, and at least one part of the positioning pin is filled with an opaque material;

the camera is used for acquiring images of the positioning pin and the reflection of the positioning pin on the liquid level of the melt;

an image processor that calculates a distance between the locating pin and the melt level based on an image of a reflection of the locating pin and the locating pin on the melt level.

Further, the positioning pin is made of opaque materials.

Further, the locating pin includes a housing portion and a filler portion.

Further, the housing portion comprises a high temperature resistant material.

Further, the housing portion comprises quartz.

Further, the housing portion comprises high transparency quartz with low impurity content.

Further, the filling portion includes an opaque material.

Further, the filling part includes graphite or silicon.

Further, an observation window is arranged on the furnace body, the camera is arranged outside the furnace body, and liquid level detection is carried out through the observation window.

The invention also provides a crystal growth device which comprises the liquid level detection device.

According to the liquid level detection device for crystal growth, at least one part of the positioning pin is filled with the opaque material, so that a camera is used for acquiring a clear image of the positioning pin arranged at the bottom of the guide cylinder and a reflection image of the positioning pin on the liquid level of the melt, the distance between the positioning pin and the liquid level of the melt is accurately calculated, and the liquid level detection device is simple and convenient to operate and low in cost.

Drawings

The following drawings of the invention are included to provide a further understanding of the invention. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

In the drawings:

FIG. 1 is a schematic view of a liquid level detection apparatus for crystal growth and a crystal growth apparatus according to an exemplary embodiment of the present invention;

fig. 2 is a schematic structural view of a locating pin according to an exemplary embodiment of the present invention.

Reference numerals

1. Furnace body 2, crystal

3. Draft tube 4, melt

5. Crucible 6 and heater

7. Crucible lifting mechanism 8 and camera

9. Positioning pin 901, housing part

902. Filling part

Detailed Description

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the invention.

In order to provide a thorough understanding of the present invention, a detailed description will be given in the following description to illustrate the liquid level detection apparatus for crystal growth of the present invention. It is apparent that the practice of the invention is not limited to the specific details familiar to those skilled in the art of crystal growth. The following detailed description of the preferred embodiments of the invention, however, the invention is capable of other embodiments in addition to those detailed.

It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular is intended to include the plural unless the context clearly dictates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Exemplary embodiments according to the present invention will now be described in more detail with reference to the accompanying drawings. These exemplary embodiments may, however, be embodied in many different forms and should not be construed as limited to only the embodiments set forth herein. It is to be understood that these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of these exemplary embodiments to those skilled in the art. In the drawings, the thicknesses of layers and regions are exaggerated for clarity, and the same elements are denoted by the same reference numerals, and thus the description thereof will be omitted.

Referring to fig. 1, the apparatus for crystal growth includes a furnace body 1, the furnace body 1 includes a crucible 5, a heater 6 is disposed at the periphery of the crucible 5, a melt 4 is disposed in the crucible 5, a crystal 2 is formed above the melt 4, and a guide cylinder 3 is disposed above the crucible 5 and around the crystal 2. As an example, the crystal 2 is a monocrystalline silicon ingot.

Illustratively, the furnace body 1 is a stainless steel cavity, and the furnace body 1 is vacuum or filled with protective gas. As an example, the protective gas is argon, the purity of the argon is more than 99.999%, the pressure is 5mbar-100mbar, and the flow rate is 70slpm-200 slpm.

Illustratively, the crucible 5 is made of a high temperature and corrosion resistant material, and the crucible 5 contains a melt 4 for crystal growth. In one embodiment, the crucible 5 comprises a quartz crucible and/or a graphite crucible. The crucible 5 contains a raw material such as polycrystalline silicon. The raw material is heated in a crucible 5 to a melt 4 for growing a single crystal silicon rod, specifically, a seed crystal is immersed in the melt, rotated and slowly pulled by a seed crystal shaft, so that silicon atoms grow along the seed crystal to a single crystal silicon rod. The seed crystal is formed by cutting or drilling a silicon single crystal with a certain crystal orientation, the common crystal orientation is <100>, <111>, <110> and the like, and the seed crystal is generally a cylinder.

Illustratively, the periphery of the crucible 5 is provided with a heater 6, and the heater 6 may be a graphite heater and may be arranged on the side and/or the bottom of the crucible 5 for electrically heating the crucible 5. Further, the heater 6 includes one or more heaters disposed around the crucible 5 to make the thermal field distribution of the crucible 5 uniform.

Illustratively, a guide shell 3 is further arranged in the furnace body 1, is positioned above the crucible 5, and is positioned outside the crystal 2 and surrounds the crystal 2, so that the heat of the melt 4 is prevented from being transferred to the furnace body 1 in the form of heat radiation and the like to cause heat loss.

Further, the crystal growing apparatus further includes a crucible elevating mechanism 7 for supporting and rotating the crucible shaft to effect elevation of the crucible 5.

Illustratively, the crystal growth process of the monocrystalline silicon crystal bar sequentially comprises the stages of seeding, shouldering, shoulder rotating, diameter equalizing and ending.

The seeding stage is first performed. Namely, after the melt 4 is stabilized to a certain temperature, the seed crystal 3 is immersed into the melt 4, and the seed crystal 3 is lifted at a certain pulling speed, so that silicon atoms grow into a thin neck with a certain diameter along the seed crystal until the thin neck reaches a preset length. The main function of the seeding process is to eliminate dislocation defects formed by the monocrystalline silicon due to thermal shock, and to utilize the supercooling degree of the crystallization front to drive silicon atoms to be sequentially arranged on the silicon solid at the solid-liquid interface to form the monocrystalline silicon. Illustratively, the drawing speed is 1.5mm/min-4.0mm/min, the length of the thin neck is 0.6-1.4 times of the diameter of the crystal bar, and the diameter of the thin neck is 4mm-6 mm.

Then, a shouldering stage is carried out, and after the neck reaches a predetermined length, the speed of pulling up the seed crystal 3 is slowed down while the temperature of the melt 4 is slightly lowered, and the lowering of the temperature is carried out in order to promote the lateral growth of the single crystal silicon, even if the diameter of the single crystal silicon is increased, and the process is called the shouldering stage.

Then, the shoulder turning stage is entered. When the diameter of the silicon single crystal is increased to a target diameter, the temperature of the melt 4 is increased by increasing the heating power of the heater 6, and the lateral growth of the silicon single crystal is suppressed and the longitudinal growth thereof is promoted by adjusting the speed of pulling up the seed crystal 3, the speed of rotation, the rotation speed of the crucible 5, and the like, so that the silicon single crystal grows nearly in the same diameter.

Then, the equal diameter stage is entered. When the diameter of the monocrystalline silicon ingot reaches a preset value, the diameter-equaling stage is carried out, and the cylindrical ingot formed in the stage is the diameter-equaling section of the ingot. Specifically, the crucible temperature, the crystal pulling speed, the crucible rotating speed and the crystal rotating speed are adjusted to stabilize the growth rate and keep the crystal diameter unchanged until the crystal pulling is finished. The isodiametric process is the main stage of growth of single crystal silicon, and can grow for dozens of hours or even more than one hundred hours.

And finally, entering a final stage. At the end of the run, the lifting rate is increased and the temperature of the melt 4 is raised so that the diameter of the ingot gradually decreases to form a cone which eventually leaves the liquid surface when the cone tip is sufficiently small. And raising the finished crystal bar to the upper furnace chamber, cooling for a period of time, and taking out to finish a growth cycle.

In the crystal growth process, it is important to measure the distance between the liquid level of the melt 4 and the guide cylinder 3, and therefore, the crystal growth apparatus provided by the present invention includes a liquid level detecting device for crystal growth, as shown in fig. 1, including:

the furnace comprises a furnace body 1, wherein a crucible 5 is arranged in the furnace body 1, and a melt 4 is contained in the crucible 5;

the guide cylinder 3 is positioned above the melt 4, a positioning pin 9 is arranged at the bottom of the guide cylinder 3, and at least one part of the positioning pin 9 is filled with an opaque material;

the camera 8 is used for acquiring images of the positioning pin 9 and the reflection of the positioning pin on the liquid level of the melt 4;

and the image processor calculates the distance between the positioning pin 9 and the liquid level of the melt 4 based on the images of the positioning pin 9 and the reflection image of the positioning pin on the liquid level of the melt.

Illustratively, the camera 8 includes any device capable of being used for optical imaging, including, but not limited to, digital cameras, high-definition video cameras, and the like. In one embodiment, the camera 8 comprises a CCD camera.

Further, the camera 8 is arranged outside the furnace body 1, and liquid level detection is performed through an observation window arranged on the furnace body 1.

Illustratively, the liquid level detection device for crystal growth provided by the invention further comprises an image processor, and the image processor can calculate the distance between the positioning pin 9 and the liquid level of the melt 4 based on the images of the positioning pin 9 and the reflection image of the positioning pin on the liquid level of the melt 4.

Because of the high-temperature environment of crystal growth, the positioning pin needs to be made of high-temperature resistant materials, transparent high-purity quartz is preferred, the quartz can be normally used at 1350 ℃, the softening temperature of the quartz is about 1700 ℃, and meanwhile, the expansion coefficient is low, so that the positioning pin is suitable for crystal growth. Further, since crystal growth has high requirements for impurities and metals and the content of impurities with high transparency is minimum, quartz is more pure and transparent as the content of impurities in quartz is lower, and the high-temperature resistance is better, a high-purity and transparent quartz pin is mostly selected as an internal positioning pin.

However, when the positioning pin 9 is made of a transparent material, the reflection of the positioning pin 9 on the liquid surface of the melt 4 is very blurred, it is difficult to accurately calculate the distance between the positioning pin 9 and the liquid surface of the melt 4 by using an image processor, and the camera 8 with higher replacement precision has no obvious effect on improving the imaging effect of the reflection, and the production cost is increased.

Based on the advantages of the transparent high-purity quartz as the positioning pin, under the condition that the transparent high-purity quartz is continuously adopted as the material of the positioning pin, in order to solve the problem that the reflection of the high-purity transparent quartz is not clear, at least one part of the positioning pin needs to be filled with an opaque material so as to achieve the purpose of clear reflection shadow.

In one embodiment, as shown in fig. 2, the positioning pin 9 includes a housing portion 901 and a filling portion 902.

Illustratively, the housing portion 901 comprises a high temperature resistant material. Further, the housing portion 901 is made of transparent high-purity quartz.

In one embodiment, the central portion of a quartz locating pin, which is widely used in the prior art, is removed to form a hollow quartz locating pin, with the quartz serving as a housing portion for the locating pin.

In one embodiment, a hollow design is used to make a hollow quartz locating pin, with the quartz serving as the housing portion of the locating pin.

Further, since the housing portion 901 is made of a transparent material, an opaque material must be used as the filling portion 902. As one example, the filled portion 902 includes, but is not limited to, graphite or silicon, based on high temperature resistance of high purity graphite, which is much higher than quartz, and a coefficient of thermal expansion less than quartz.

For the quartz positioning pin widely adopted in the prior art, the positioning pin 9 of the liquid level detection device for crystal growth can be used as the positioning pin 9 only by forming a hollow part and filling opaque materials in the hollow part, the manufacturing difficulty is low, the cost is low, the imaging effect of reflection can be obviously improved, and the distance between the positioning pin 9 and the liquid level of the melt 4 can be accurately calculated.

According to the liquid level detection device for crystal growth, the camera is used for obtaining the clear image of the reflection of the positioning pin arranged at the bottom of the guide cylinder and the positioning pin on the liquid level of the melt, so that the distance between the positioning pin and the liquid level of the melt is accurately calculated, and the liquid level detection device is simple and convenient to operate and low in cost.

The present invention has been illustrated by the above embodiments, but it should be understood that the above embodiments are for illustrative and descriptive purposes only and are not intended to limit the invention to the scope of the described embodiments. Furthermore, it will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that many variations and modifications may be made in accordance with the teachings of the present invention, which variations and modifications are within the scope of the present invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.