阅读说明：本技术 一种生长czt单晶锭的方法 (Method for growing CZT single crystal ingot ) 是由 庞昊 谢雨凌 于 2021-04-26 设计创作，主要内容包括：本发明公开了一种生长CZT单晶锭的方法,属于半导体材料制造工艺技术领域,该种生长CZT单晶锭的方法,包括以下步骤：步骤A、将无定形无定形三氧化二硼和微米级石墨粉质量比混合形成混合浆料；步骤B、将混合浆料以刷浆法或脉冲电弧放电沉积法均匀涂覆在热解氮化硼坩埚内壁上；步骤C、将碲化锌多晶体合成料置于热解氮化硼坩埚内放肩区,并在籽晶区放入籽晶,然后将热解氮化硼坩埚放入石英容器内,加热熔融、冷却、CZT单晶锭生长,生长完成后获得一种CZT单晶锭。且本发明将无定形三氧化二硼和石墨粉混合形成混合浆料涂覆在热解氮化硼坩埚内壁上,使得生长平面和切割面的夹角小于4°,减小CZT衬底片上不同区域的Zn元素含量波动。(The invention discloses a method for growing a CZT single crystal ingot, which belongs to the technical field of semiconductor material manufacturing process and comprises the following steps: step A, mixing amorphous boron trioxide and micron-sized graphite powder in a mass ratio to form mixed slurry; b, uniformly coating the mixed slurry on the inner wall of the pyrolytic boron nitride crucible by a slurry brushing method or a pulse arc discharge deposition method; and step C, placing the zinc telluride polycrystal synthetic material in a shoulder area in a pyrolytic boron nitride crucible, placing seed crystals in a seed crystal area, then placing the pyrolytic boron nitride crucible in a quartz container, heating, melting, cooling, growing CZT single crystal ingots, and obtaining the CZT single crystal ingots after the growth is finished. In addition, amorphous diboron trioxide and graphite powder are mixed to form mixed slurry, and the mixed slurry is coated on the inner wall of the pyrolytic boron nitride crucible, so that the included angle between a growth plane and a cutting surface is smaller than 4 degrees, and the fluctuation of the Zn element content in different regions on the CZT substrate is reduced.)

1. A method of growing CZT single crystal ingots using as a container a pyrolytic boron nitride crucible comprising an ingot region (10), a shouldering region (20) and a seed region (30), comprising the steps of:

step A, mixing amorphous boron trioxide and micron-sized graphite powder in a mass ratio to form mixed slurry;

b, uniformly coating the mixed slurry on the inner wall of the pyrolytic boron nitride crucible by a slurry brushing method or a pulse arc discharge deposition method;

and step C, placing the tellurium-zinc-cadmium polycrystal synthetic material in a shoulder region (20) in a pyrolytic boron nitride crucible, placing seed crystals in a seed crystal region (30), then placing the pyrolytic boron nitride crucible in a vacuum closed quartz container, heating, melting, cooling and growing the CZT single crystal ingot, and obtaining the CZT single crystal ingot after the growth is finished.

2. The method for growing a CZT single crystal ingot according to claim 1, wherein in the step a, the micron-sized graphite powder has an average particle size of less than 50 μm, and a mass ratio of the amorphous diboron trioxide to the micron-sized graphite powder is 82-87: 12-18.

3. A method of growing a CZT single crystal ingot according to claim 1, wherein in the step B, the thickness of the coating layer of the mixed slurry on the inner wall of the pyrolytic boron nitride crucible is 2-3 mm.

4. A method of growing a CZT single crystal ingot according to claim 1, wherein in the step B, the slurry method is operated as follows: and uniformly coating the slurry on the inner layer of the crucible, rotating the crucible for 15-25s after coating, keeping the rotating speed at 440RPM for 360 plus materials, then putting the rotated crucible into a furnace at 120 plus materials and 143 ℃ for heat preservation for 9-11 hours, and then cooling along with the furnace to finish coating.

5. A method of growing a CZT single crystal ingot according to claim 1, wherein the melt temperature in step C is 1103-.

6. A method of growing a CZT single crystal ingot according to claim 1, wherein the temperature gradient in step C is 1-10 ℃; the growth speed of the CZT single crystal ingot is 0.5-2 mm/h; the length-diameter ratio of the obtained CZT single crystal ingot is 1.3-1.7.

Technical Field

The invention belongs to the technical field of semiconductor material manufacturing processes, and particularly relates to a method for growing a CZT single crystal ingot.

Background

Cadmium zinc telluride (CdZnTe), hereinafter abbreviated as CZT, is an important compound semiconductor material, and a substrate slice made of CZT single crystals is one of key raw materials for manufacturing Mercury Cadmium Telluride (MCT) detectors (currently mainstream middle-high end infrared detectors). CZT can play a role in this function, and the crystallographic parameters can be obtained by regulating the content ratio of Zn element, so as to meet the growth requirements of different MCT crystals. Therefore, the content of Zn element is one of the key indicators for evaluating the quality of CZT crystal as an epitaxial growth substrate.

In the prior art, the growth of CZT single crystal adopts the principle of solidifying liquid into solid, namely, the CZT crystal is grown in a high-temperature furnace by a melt method, and the principle of the growth of the CZT single crystal is realized by the temperature gradient in the furnace body. The principal methods for growing CZT crystals by the melt method include the bridgman method (bridgman) and the Vertical Gradient Freeze (VGF). However, the fluctuation of the Zn element content in different areas of the CZT substrate slice prepared by growing the CZT crystal by the melt method is large, so that the crystallographic parameters of the CZT crystal are uncontrollable, the yield of the CZT substrate slice is directly reduced due to the large fluctuation of the Zn element content in the CZT substrate slice, even the growth and the qualification rate of MCT crystal are influenced, and the growth cost is increased. The reasons for causing the great fluctuation of the Zn element content in different regions of the CZT substrate sheet can be divided into the following aspects:

1. whether the CZT single crystal is grown by the Bridgman method or the vertical gradient solidification method, the growth of the CZT single crystal is a very slow process, the growth process is approximate to a quasi-steady state process, and the distribution coefficient (slightly different according to the composition and the common value is 1.35) of Zn element determines that the distribution of the Zn element in the whole crystal ingot is not uniform;

2. the CZT crystal used as the substrate must have a (111) plane or a (211) plane as a cut surface, and the (111) plane is selected for cutting in most cases. The crystal ingot grown by the prior art cannot ensure that the plane (111) of the growth plane is controlled within an acceptable range, so that the cutting plane and the growth plane always form a certain angle, the growth process of CZT determines that the distribution of Zn on the same growth plane is always uniform, and the existence of the angle causes the substrate slice prepared by the working procedures of cutting, grinding and polishing and the like, and the Zn content of the substrate slice is limited by the Zn distribution trend of the whole crystal ingot in the solidification direction and has larger fluctuation.

Therefore, the invention provides a method for growing a CZT single crystal ingot, which aims to solve the problem that the content fluctuation of Zn elements in different regions of a substrate is large.

Disclosure of Invention

The invention aims to provide a method for growing a CZT single crystal ingot, which aims to solve the problem that the content fluctuation of Zn elements in different regions of a substrate is large.

The purpose of the invention can be solved by the following technical scheme:

a method of growing a CZT single crystal ingot comprising the steps of:

step A, mixing amorphous boron trioxide and micron-sized graphite powder in a mass ratio to form mixed slurry;

b, uniformly coating the mixed slurry on the inner wall of the pyrolytic boron nitride crucible by a slurry brushing method or a pulse arc discharge deposition method;

and step C, placing the tellurium-zinc-cadmium polycrystal synthetic material in an inner shoulder area of a boron nitride crucible, placing seed crystals in a seed crystal area, then placing the pyrolytic boron nitride crucible in a closed quartz container, vacuumizing the quartz container, heating, melting, cooling and growing the CZT single crystal ingot, and obtaining the CZT single crystal ingot after the growth is finished.

Further, the pyrolytic boron nitride crucible comprises an ingot area, a shouldering area and a seed crystal area, wherein the ingot area is arranged at the top of the shouldering area and is cylindrical, the shouldering area is arranged at the top of the seed crystal area and is in a right circular cone shape, and the seed crystal area is cylindrical.

Further, the ingot region has a size of 111mm phi (145mm-190mm), the top angle of the shouldering region is 107 DEG, and the seed region has a size of 1.7mm phi 57 mm.

Further, in the step A, the average grain diameter of the micron-sized graphite powder is less than 50 microns, and the mass ratio of the amorphous diboron trioxide to the micron-sized graphite powder is 82-87: 12-18.

Further, in the step B, the thickness of the coating of the mixed slurry on the inner wall of the pyrolytic boron nitride crucible is 2-3 mm.

Further, in the step B, the slurry is uniformly coated on the inner layer of the crucible, the crucible is rotated for 15-25s after the coating is finished, the rotating speed is 360-.

Further, the melt temperature in step C is 1103-1110 ℃, preferably 1106 ℃.

Further, the temperature gradient in step C is 1-10 deg.C, preferably 7 deg.C.

Further, the growth rate of the CZT single crystal ingot in step C is 0.5-2mm/h, preferably 1.2 mm/h.

Further, the CZT single crystal ingot obtained in step C has an aspect ratio of 1.3 to 1.7, preferably 1.6.

The invention has the beneficial effects that:

1. according to the invention, amorphous diboron trioxide and micron-grade graphite powder are mixed according to the mass ratio to form mixed slurry, the mixed slurry is coated on the inner wall of the pyrolytic boron nitride crucible, so that the included angle between the growth plane and the cutting plane is smaller than 4 degrees, the problem of Zn element content fluctuation of different regions on the substrate sheet caused by overlarge angles between the cutting plane and the growth plane can be solved, the quality and the qualification rate of the CZT substrate sheet are effectively improved, and the growth cost of the CZT substrate sheet is reduced.

2. The CZT single crystal ingot growth method adopted by the invention has the advantages of less twin crystals, less tellurium precipitation, simple growth method and easy control.

Drawings

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

FIG. 1 is a pyrolytic boron nitride crucible for use in the present invention.

In the drawings, the components represented by the respective reference numerals are listed below: 10. an ingot region; 20. placing a shoulder area; 30. a seed crystal region.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1, the pyrolytic boron nitride crucible comprises an ingot region 10, a shoulder region 20 and a seed crystal region 30, the ingot region 10 is disposed on the upper portion of the shoulder region 20 and is cylindrical, the shoulder region 20 is disposed on the upper portion of the seed crystal region 30 and is right conical, and the seed crystal region 30 is cylindrical.

Example 1:

a method of growing a CZT single crystal ingot comprising the steps of:

step A, mixing amorphous boron trioxide and micron-sized graphite powder according to a mass ratio of 82:12 to form mixed slurry, wherein the average particle size of the micron-sized graphite powder is 45 microns;

step B, coating the mixed slurry on the inner wall of the pyrolytic boron nitride crucible, wherein the thickness of the coating is 2mm, rotating the crucible for 15s at the rotating speed of 360RPM after the coating is finished, then putting the rotated crucible into a 120 ℃ furnace, preserving heat for 9 hours, and cooling along with the furnace to finish the coating;

and step C, placing the tellurium-zinc-cadmium polycrystal synthetic material with the purity of 7N in a boron nitride crucible in a shouldering area, placing seed crystals in the seed crystal area, then placing the pyrolytic boron nitride crucible in a closed quartz container, vacuumizing the quartz container, heating, melting, cooling and growing the CZT single crystal ingot, and obtaining the CZT single crystal ingot after the growth is finished, wherein the melt temperature is 1103 ℃, the temperature gradient is 1 ℃, the growth speed is 0.5mm/h, and the length-diameter ratio is 1.3.

Wherein, the size of the ingot zone 10 in the adopted pyrolytic boron nitride crucible is phi 111 mm/144 mm, the top angle of the shouldering zone 20 is 107 degrees, and the size of the seed crystal zone 30 is phi 1.7 mm/57 mm.

Cutting and polishing the prepared CZT single crystal ingot to obtain a substrate slice with the thickness of 50mm x 50mm, then selecting 20 points on the substrate slice to measure the Zn content to obtain 20 groups of data, and calculating the range difference and the average difference of the group of data to obtain the range difference R of 0.08 and the average difference MD of 0.0357.

Example 2:

step A, mixing amorphous boron trioxide and micron-sized graphite powder according to a mass ratio of 85:15 to form mixed slurry, wherein the average particle size of the micron-sized graphite powder is 40 micrometers;

step B, coating the mixed slurry on the inner wall of the pyrolytic boron nitride crucible, wherein the thickness of the coating is 2.5mm, rotating the crucible for 15s after the coating is finished, the rotating speed is 400RPM, then putting the rotated crucible into a 130 ℃ furnace, preserving heat for 10 hours, and cooling along with the furnace to finish the coating;

and step C, placing the tellurium-zinc-cadmium polycrystal synthetic material with the purity of 7N in a boron nitride crucible in an inner shoulder area, placing seed crystals in the seed crystal area, then placing the pyrolytic boron nitride crucible in a closed quartz container, vacuumizing the quartz container, heating, melting, cooling and growing the CZT single crystal ingot, and obtaining the CZT single crystal ingot after the growth is finished, wherein the melt temperature is 1106 ℃, the temperature gradient is 7 ℃, the growth speed is 1.5mm/h, and the length-diameter ratio is 1.6.

Wherein, the size of an ingot zone 10 in the adopted pyrolytic boron nitride crucible is phi 111 mm/178 mm, the top angle of a shouldering zone 20 is 107 degrees, and the size of a seed crystal zone 30 is phi 1.7 mm/57 mm.

Cutting and polishing the prepared CZT single crystal ingot to obtain a substrate slice with the thickness of 50mm x 50mm, measuring the Zn content at 15 points on the substrate slice to obtain 15 groups of data, and calculating the range difference and the average difference of the data to obtain the range difference R of 0.064 and the average difference MD of 0.0344.

Example 3:

step A, mixing amorphous boron trioxide and micron-sized graphite powder according to a mass ratio of 85:15 to form mixed slurry, wherein the average particle size of the micron-sized graphite powder is 40 micrometers;

step B, coating the mixed slurry on the inner wall of the pyrolytic boron nitride crucible, wherein the thickness of the coating is 2.5mm, rotating the crucible for 25s after the coating is finished, and keeping the temperature of the rotated crucible in a 143-DEG C furnace for 11 hours, and then cooling the crucible along with the furnace to finish the coating;

and step C, placing the tellurium-zinc-cadmium polycrystal synthetic material with the purity of 7N in a boron nitride crucible in an inner shoulder area, placing seed crystals in the seed crystal area, then placing the pyrolytic boron nitride crucible in a closed quartz container, vacuumizing the quartz container, heating, melting, cooling and growing the CZT single crystal ingot, and obtaining the CZT single crystal ingot after the growth is finished, wherein the melt temperature is 1106 ℃, the temperature gradient is 7 ℃, the growth speed is 1.5mm/h, and the length-diameter ratio is 1.6.

Wherein, the size of an ingot zone 10 in the adopted pyrolytic boron nitride crucible is phi 111 mm/178 mm, the top angle of a shouldering zone 20 is 107 degrees, and the size of a seed crystal zone 30 is phi 1.7 mm/57 mm.

Cutting and polishing the prepared CZT single crystal ingot to obtain a substrate slice with the thickness of 50mm x 50mm, then selecting 25 points on the substrate slice to measure the Zn content to obtain 25 groups of data, and calculating the range difference and the average difference of the group of data to obtain the range difference R of 0.061 and the average difference MD of 0.0319.

Example 4:

step A, mixing amorphous boron trioxide and micron-sized graphite powder according to a mass ratio of 85:15 to form mixed slurry, wherein the average particle size of the micron-sized graphite powder is 35 microns;

step B, uniformly coating the mixed slurry on the inner wall of the pyrolytic boron nitride crucible by a pulse arc discharge deposition method, wherein the thickness of the coating is 3mm, and finishing coating;

and step C, placing the tellurium-zinc-cadmium polycrystal synthetic material with the purity of 7N in a boron nitride crucible in a shouldering area, placing seed crystals in the seed crystal area, then placing the pyrolytic boron nitride crucible in a closed quartz container, vacuumizing the quartz container, heating, melting, cooling and growing the CZT single crystal ingot to obtain the CZT single crystal ingot after the growth is finished, wherein the melt temperature is 1110 ℃, the temperature gradient is 10 ℃, the growth speed is 2mm/h, and the length-diameter ratio is 1.7.

Wherein, the size of an ingot zone 10 in the adopted pyrolytic boron nitride crucible is phi 111mm 189mm, the top angle of a shouldering zone 20 is 107 degrees, and the size of a seed crystal zone 30 is phi 1.7mm 57 mm.

And cutting and polishing the prepared CZT single crystal ingot to obtain a substrate slice with the thickness of 50mm x 50mm, selecting 20 points on the substrate slice to measure the Zn content to obtain 20 groups of data, and calculating the range difference and the average difference of the group of data to obtain the range difference R of 0.066 and the average difference MD of 0.0337.

Comparative example 1:

a CZT substrate slice is purchased in the market, 20 points are selected on the substrate slice to measure the Zn content, 20 groups of data are obtained, and the group of data is calculated to have the range difference R of 0.12 and the average difference MD of 0.1013.

The Zn content test data on CZT substrate sheets from examples 1-4 and comparative example 1 above are shown below.

From the above data, it can be seen that the measured numerical value dispersion degree of the Zn content on the CZT substrate sheets obtained in examples 1 to 4 is lower than the numerical value on the Zn content side on the CZT substrate sheet in comparative example 1, which indicates that the fluctuation of the Zn content on the CZT substrate sheet obtained by the present invention is smaller than the fluctuation of the Zn content on the CZT substrate sheet in comparative example 1, i.e. that the growth method provided by the present invention can reduce the fluctuation of the Zn elemental content in different regions on the substrate sheet and improve the quality of the CZT substrate sheet.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing is merely exemplary and illustrative of the principles of the present invention and various modifications, additions and substitutions of the specific embodiments described herein may be made by those skilled in the art without departing from the principles of the present invention or exceeding the scope of the claims set forth herein.