阅读说明：本技术 一种大尺寸锗单晶生长方法 (Large-size germanium single crystal growth method ) 是由 黄治成 熊聪 郭晨光 尹士平 黄雪丽 于 2021-09-17 设计创作，主要内容包括：本发明公开了一种大尺寸锗单晶生长方法,包括以下步骤：S100：将高纯度的区熔锗锭装入石墨坩埚中进行高温熔化为熔体,将籽晶插入所述熔体表面进行熔接；S200：引晶阶段；S300：缩径阶段；S400：放肩阶段；S500：等径阶段；S600：收尾脱离阶段；S700：降温退火阶段。该大尺寸锗单晶生长方法通过在等径阶段中的前阶段、中阶段和后阶段三个阶段不断的提高坩埚的埚转速率,使得坩埚出现离心力,通过离心力降低熔体的中间液面的凸起幅度,使得熔体的中间液面和周围液面的高度保持一致,从而使得液面保持平整,当晶体在平整的液面中生长时,就不容易出现变晶现象。因此,该大尺寸锗单晶生长方法有效避免大尺寸锗单晶在生长过程中出现变晶现象,提高产品的良率。(The invention discloses a method for growing a large-size germanium single crystal, which comprises the following steps: s100: loading a high-purity zone-melting germanium ingot into a graphite crucible, melting at high temperature to obtain a melt, and inserting a seed crystal into the surface of the melt for fusion welding; s200: a seeding stage; s300: reducing the diameter; s400: a shouldering stage; s500: a diameter-equaling stage; s600: a final separation stage; s700: and (5) cooling and annealing. According to the large-size germanium single crystal growth method, the crucible rotation rate of the crucible is continuously increased in the front stage, the middle stage and the rear stage in the equal-diameter stage, so that centrifugal force occurs in the crucible, the protruding amplitude of the middle liquid level of the melt is reduced through the centrifugal force, the heights of the middle liquid level and the surrounding liquid level of the melt are kept consistent, the liquid level is kept flat, and when crystals grow in the flat liquid level, the crystal change phenomenon is not easy to occur. Therefore, the method for growing the large-size germanium single crystal effectively avoids the phenomenon of crystal transformation of the large-size germanium single crystal in the growing process and improves the yield of products.)

1. A method for growing a large-size germanium single crystal is characterized by comprising the following steps:

s100: loading a high-purity zone-melting germanium ingot into a graphite crucible, melting at high temperature to obtain a melt, and inserting a seed crystal into the surface of the melt for fusion welding;

s200: in the seeding stage, a crystal is led out from the seed crystal, so that the diameter of the crystal is 5mm-7mm, and the length of the crystal is 250mm-300 mm;

s300: in the diameter reducing stage, the pulling speed of the crystal is adjusted to be 2-2.5mm/min, the crystal of the crystal is adjusted to be 4r/min-6r/min, and the crucible of the crucible is adjusted to be 1.5r/min-3 r/min;

s400: in the shouldering stage, reducing the pulling speed of the crystal in the growth process, and linearly cooling the crystal when the pulling speed is reduced to a preset pulling speed and the length of the crystal is a preset length;

when the diameter of the crystal reaches a preset diameter, crucible lift feeding is carried out on the crucible;

s500: the constant diameter stage comprises a pre-constant diameter stage, a middle constant diameter stage and a post-constant diameter stage, when the crystal is in the pre-constant diameter stage, the crucible rotation rate of the crucible is adjusted to be 1.5r/min-2r/min, when the crystal is in the middle constant diameter stage, the crucible rotation rate of the crucible is adjusted to be 2r/min-2.5r/min, and when the crystal is in the post-constant diameter stage, the crucible rotation rate of the crucible is adjusted to be 2.5r/min-3 r/min;

s600: a final separation stage: lowering the crucible to separate the crystal from the melt, and adjusting the distance between the crystal and the liquid level of the melt to be a preset distance;

s700: and (3) cooling and annealing: and adjusting the cooling rate in the crucible by stages to perform cooling annealing on the crystal.

2. The method for growing large-size germanium single crystals according to claim 1, further comprising cleaning the high-purity zone-melting germanium ingot before S100.

3. The method for growing a large-size germanium single crystal according to claim 1, wherein in S400, the predetermined pulling rate is 0.3mm/min to 0.5mm/min, and the predetermined length is 230mm to 250 mm.

4. The method for growing large-size germanium single crystals according to claim 1, wherein in the step S400, the linear cooling rate is 2-3 ℃/min.

5. The method for growing a large-size germanium single crystal according to claim 1, wherein in the step S400, when the crystal is linearly cooled, the angle between the crystal and the liquid level of the melt is 50 ° to 65 °.

6. The method for growing a large-size germanium single crystal according to claim 1, wherein the predetermined diameter is 170mm or more in S400.

7. The method for growing a large-size germanium single crystal according to claim 1, wherein in the S400, the crucible-lift rate is 0.01mm/min to 0.02 mm/min.

8. The method for growing large-size germanium single crystals according to claim 1, wherein the predetermined distance is 50mm to 100mm in S600.

9. The method for growing large-size germanium single crystals according to claim 1, wherein in S600, the temperature rise is performed with a small amplitude before the crystal and the melt are separated.

10. The method for growing a large-size germanium single crystal according to claim 1, wherein in S700, when the temperature in the crucible is greater than 800 ℃, the cooling rate is controlled to be 1 ℃/min; when the temperature in the crucible is between 600 ℃ and 800 ℃, controlling the cooling speed to be 3 ℃/min; when the temperature in the crucible is between 300 ℃ and 600 ℃, controlling the cooling speed to be 5 ℃/min; and when the temperature in the crucible is less than 300 ℃, powering off the crucible and naturally cooling.

Technical Field

The invention relates to the technical field of germanium single crystals, in particular to a large-size germanium single crystal growth method.

Background

With the continuous development of the application market of germanium single crystals, the demand for large-size germanium single crystals of more than 100kg is greater and greater, and the requirement for the crystal quality of the germanium single crystals is also increased continuously. The CZ method is generally adopted as a process method for producing germanium single crystals, and when the current CZ method is used for producing large-size germanium single crystals with the weight of more than 100kg, the crucible rotation speed of a crucible cannot be effectively controlled, so that the liquid level of a melt cannot be guaranteed to be flat, and the phenomenon that the grown germanium single crystals are easy to generate crystal transformation is caused.

Therefore, how to effectively avoid the phenomenon of crystal transformation of the large-size germanium single crystal during the growth process and improve the yield of the product is a technical problem that needs to be solved by those skilled in the art.

Disclosure of Invention

In view of the above, the present invention provides a method for growing a large-size germanium single crystal, which can effectively avoid the phenomenon of crystal transformation of the large-size germanium single crystal during the growth process, and improve the yield of products.

In order to achieve the purpose, the invention provides the following technical scheme:

a method for growing a large-size germanium single crystal comprises the following steps:

s100: loading a high-purity zone-melting germanium ingot into a graphite crucible, melting at high temperature to obtain a melt, and inserting a seed crystal into the surface of the melt for fusion welding;

s200: in the seeding stage, a crystal is led out from the seed crystal, so that the diameter of the crystal is 5mm-7mm, and the length of the crystal is 250mm-300 mm;

s300: in the diameter reducing stage, the pulling speed of the crystal is controlled to be 2-2.5mm/min, the crystal of the crystal is controlled to be 4-6 r/min, and the crucible of the crucible is controlled to be 1.5-3 r/min;

s400: in the shouldering stage, reducing the pulling speed of the crystal in the growth process, and linearly cooling the crystal when the pulling speed is reduced to a preset pulling speed and the length of the crystal is a preset length;

and when the diameter of the crystal reaches a preset diameter, performing crucible-liter material supplementing on the crucible.

S500: and the constant diameter stage comprises a pre-constant diameter stage, a middle constant diameter stage and a post-constant diameter stage, when the crystal is in the pre-constant diameter stage, the crucible rotation rate of the crucible is adjusted to be 1.5r/min-2r/min, when the crystal is in the middle constant diameter stage, the crucible rotation rate of the crucible is adjusted to be 2r/min-2.5r/min, and when the crystal is in the post-constant diameter stage, the crucible rotation rate of the crucible is adjusted to be 2.5r/min-3 r/min.

S600: a final separation stage: and lowering the crucible to separate the crystal from the melt, and adjusting the distance between the crystal and the liquid level of the melt to be a preset distance.

S700: and (3) cooling and annealing: and adjusting the cooling rate in the crucible by stages to perform cooling annealing on the crystal.

Preferably, before S100, the method further comprises cleaning the high-purity zone-melting germanium ingot.

Preferably, in the step S400, the preset pulling speed is 0.3mm/min to 0.5mm/min, and the preset length is 230mm to 250 mm.

Preferably, in the step S400, the linear cooling rate is 2 to 3 ℃/min.

Preferably, in S400, when the crystal is linearly cooled, the included angle between the crystal and the liquid level of the melt is 50 ° to 65 °.

Preferably, in S400, the preset diameter is 170mm or more.

Preferably, in the S400, the rate of crucible rise is 0.01mm/min to 0.02 mm/min.

Preferably, in S600, the preset distance is 50mm to 100 mm.

Preferably, in S600, the crystal and the melt are subjected to a small temperature rise before being separated.

Preferably, in S700, when the temperature in the crucible is greater than 800 ℃, the cooling rate is controlled to be 1 ℃/min; when the temperature in the crucible is between 600 ℃ and 800 ℃, controlling the cooling speed to be 3 ℃/min; when the temperature in the crucible is between 300 ℃ and 600 ℃, controlling the cooling speed to be 5 ℃/min; and when the temperature in the crucible is less than 300 ℃, powering off the crucible and naturally cooling.

According to the technical scheme, the crucible rotation rate of the crucible is continuously increased in the front stage, the middle stage and the rear stage of the equal-diameter stage, so that the crucible generates centrifugal force, the projection amplitude of the middle liquid level of the melt is reduced through the centrifugal force, the heights of the middle liquid level and the peripheral liquid level of the melt are kept consistent, the liquid level is kept flat, and the phenomenon of crystal change is not easy to occur when crystals grow in the flat liquid level. Therefore, the method for growing the large-size germanium single crystal effectively avoids the phenomenon of crystal transformation of the large-size germanium single crystal in the growing process and improves the yield of products.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art are briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a flow chart of a germanium single crystal growth method disclosed in an embodiment of the present invention.

FIG. 2 is a schematic structural view of a finished germanium single crystal produced by a prior art process;

fig. 3 is a schematic structural view of a germanium single crystal produced by the process of the embodiment of the present invention.

Detailed Description

In view of the above, the core of the present invention is to provide a method for growing a large-size germanium single crystal, which can effectively avoid the crystal transformation phenomenon of the large-size germanium single crystal during the growth process, and improve the yield of the product.

In order to make the technical field of the invention better understand, the invention is further described in detail with reference to the accompanying drawings and the specific embodiments, and please refer to fig. 1 to 3.

The inventor researches and discovers that a plurality of factors influencing the crystallization of the germanium single crystal include: 1) the crucible rotation rate of the crucible; 2) temperature change during diameter reduction; 3) temperature change gradient in the shoulder rotating process; 4) whether the crucible lift is not matched with the crystal lift rate or not; 5) temperature changes during the isodiametric process; 6) temperature changes during growth. Particularly, the crucible rotation rate of the crucible is an important factor influencing the crystal transformation of the germanium single crystal, because the graphite crucible is heated annularly, under the molten state, the intermediate temperature of the solution in the graphite crucible is low, the peripheral temperature is high, the germanium metal is cold-expanded and hot-shrunk (different from other metals), and the temperature is faster along with the longitudinal transfer of the crystal (slower in transverse transfer) when the germanium metal starts to grow, so the intermediate of the solution in the initial growth stage is convex, the centrifugal force can appear after the crucible rotation is improved, the centrifugal force can reduce the convex amplitude of the intermediate liquid level of the solution, and therefore, the crucible rotation rate of the crucible and the flatness of the liquid level of the melt have a great relationship.

Based on the reasons, the flatness of the melt liquid level can be changed by changing the crucible rotation rate, and the occurrence of the phenomenon of crystal transformation can be avoided by improving the flatness of the melt liquid level.

Referring to fig. 1, a method for growing a large-size germanium single crystal according to an embodiment of the present invention includes the following steps: s100: loading a high-purity zone-melting germanium ingot into a graphite crucible, melting at high temperature to obtain a melt, and inserting a seed crystal into the surface of the melt for fusion welding;

s200: in the seeding stage, a crystal is led out from the seed crystal, so that the diameter of the crystal is 5mm-7mm, and the length of the crystal is 250mm-300 mm;

s300: in the diameter reducing stage, the pulling speed of the crystal is adjusted to be 2-2.5mm/min, the crystal of the crystal is adjusted to be 4r/min-6r/min, and the crucible of the crucible is adjusted to be 1.5r/min-3 r/min;

s400: in the shouldering stage, the pulling speed of the crystal in the growth process is reduced, and when the pulling speed is reduced to the preset pulling speed and the length of the crystal is the preset length, the crystal is linearly cooled;

and when the diameter of the crystal reaches a preset diameter, performing crucible-liter material supplementing on the crucible.

S500: and the isodiametric stage comprises an isodiametric front stage, an isodiametric middle stage and an isodiametric rear stage, when the crystal is in the isodiametric front stage, the crucible rotating speed of the crucible is adjusted to be 1.5r/min-2r/min, when the crystal is in the isodiametric middle stage, the crucible rotating speed of the crucible is adjusted to be 2r/min-2.5r/min, and when the crystal is in the isodiametric rear stage, the crucible rotating speed of the crucible is adjusted to be 2.5r/min-3 r/min.

S600: a final separation stage: and lowering the crucible to separate the crystal from the crucible, and controlling the distance between the crystal and the liquid level of the melt to be a preset distance.

S700: and (3) cooling and annealing: and cooling and annealing the crystal in a sectional linear cooling mode.

According to the embodiment of the invention, the crucible rotation rate of the crucible is continuously increased in the front stage, the middle stage and the rear stage of the equal-diameter stage, so that the crucible generates centrifugal force, the projection amplitude of the middle liquid level of the melt is reduced through the centrifugal force, and the heights of the middle liquid level and the peripheral liquid level of the melt are kept consistent, so that the liquid level is kept flat, and the phenomenon of crystal change is not easy to occur when the crystal grows in the flat liquid level. Therefore, the method for growing the large-size germanium single crystal effectively avoids the phenomenon of crystal transformation of the large-size germanium single crystal in the growing process and improves the yield of products.

In order to optimize the above embodiment, the present invention further discloses a germanium single crystal growth method, which further includes a cleaning step of cleaning a high-purity zone-melting germanium ingot before S100.

In order to further optimize the above embodiments, in the germanium single crystal growth method disclosed in the embodiments of the present invention, in S400, a mode that the pulling rate of the crystal needs to be reduced is first selected to achieve the shoulder-off effect, and after the pulling rate is stabilized and the shoulder does not grow any further, that is, the pulling rate reaches the preset pulling rate, and when the length of the crystal is the preset length, the shoulder effect is achieved by linear cooling.

The embodiment of the invention does not limit the specific values of the preset pulling speed and the preset length of the crystal, and the structure meeting the use requirements of the invention is within the protection scope of the invention.

In order to optimize the above embodiment, in S400, the preset pulling speed disclosed by the embodiment of the present invention is preferably 0.3mm/min to 0.5mm/min, and the preset length is preferably 230mm to 250mm, so that the crystal can achieve a better shouldering effect.

Currently, in S400, the embodiment of the present invention does not specifically limit the specific rate of the linear cooling, and the structure that meets the usage requirement of the present invention is within the protection scope of the present invention.

In order to optimize the above embodiment, in S400, the linear cooling rate disclosed in the embodiment of the present invention is preferably 2-3 ℃/min.

It should be noted that when the crystal is shouldered in a linear cooling mode, the included angle between the crystal and the liquid level of the melt is preferably 50-65 degrees, and the pulling speed of the crystal is reduced to the growth speed in the equal-diameter stage, and the shouldered crystal reaches the preset diameter, wherein the preset diameter is preferably more than 170 mm.

When the preset diameter of the crystal reaches the target diameter, the shoulder correction effect is realized through linear temperature rise, the correction time is controlled to be about 1-1.5h, and the crystal slowly grows to the target diameter range.

When the diameter of the crystal reaches the target diameter range, namely more than 170mm, the material is supplemented through crucible lift, wherein the rate of crucible lift is 0.01mm/min-0.02mm/min, and thus, the phenomenon that the crystal is changed or dislocation is formed due to the fact that the material is less in the large-diameter shoulder portion can be effectively avoided.

In order to further optimize the above embodiment, in S600 disclosed in the embodiment of the present invention, the crucible is lowered to separate the crystal from the melt, and the distance between the crystal and the liquid level of the melt is preferably adjusted to 50mm to 100 mm.

On the basis of the above embodiment, in order to further optimize the above embodiment, in the germanium single crystal growth method disclosed in the embodiment of the present invention, in the ending detachment stage in S600, in order to avoid the phenomenon of sticking to the pot of the large-diameter germanium single crystal, in the germanium single crystal growth method disclosed in the embodiment of the present invention, a small-amplitude temperature rise is performed before the crystal and the melt are separated, so as to avoid the probability of cracking at the tail of the germanium single crystal.

When the crystal and the melt are separated, the balance of the bottom material of the crucible bottom is about 25kg to 35 kg. In the method for growing the large-size germanium single crystal disclosed by the embodiment of the invention, in the cooling annealing stage of S700, when the temperature in the crucible is more than 800 ℃, the cooling speed is controlled to be 1 ℃/min; when the temperature in the crucible is between 600 ℃ and 800 ℃, controlling the cooling speed to be 3 ℃/min; when the temperature in the crucible is between 300 ℃ and 600 ℃, controlling the cooling speed to be 5 ℃/min; and when the temperature in the crucible is less than 300 ℃, powering off the crucible and naturally cooling. The large-size germanium single crystal grown by the method can effectively avoid the phenomenon of crystal transformation and improve the yield of products.

By comparing the crucible rotation rate and the finished product effect of the comparative example and the example, it can be found that the germanium single crystal finished product produced by the process of the comparative example shows the phenomenon of crystal transformation, and the germanium single crystal finished product produced by the process of the example does not show the phenomenon of crystal transformation.

Referring to the comparative data in the table, fig. 2 and fig. 3 show, wherein fig. 2 shows a germanium single crystal product obtained by a conventional process, and fig. 3 shows a germanium single crystal product obtained by a process according to an embodiment of the present invention.

In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are intended to be inclusive and mean, for example, that they may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.