Heat shield radiation device for improving crystallization rate of heavily doped red phosphorus single crystal

Abstract

The invention relates to the technical field of wafer manufacturing equipment, in particular to a heat shield radiation device for improving the crystallization rate of heavily doped red phosphorus single crystals, which comprises a support ring, an upper heat insulation material mounted at the top of the support ring, and an outer heat shield assembly mounted at the bottom of the support ring, the outer heat shield assembly comprises a heat shield outer cover and a heat shield inner cover, the heat shield outer cover and the heat shield inner cover are both of an annular structure and are connected with each other, a cavity is formed between the inner cover and the outer cover, and the cavity is filled with an inner heat insulation material; the heat shield inner cover is composed of an inner upper cover, an inner lower cover and an inner upper molybdenum cylinder, the inner upper cover and the inner upper molybdenum cylinder are both of a V-shaped structure, the inner upper molybdenum cylinder is arranged on the inner wall of the inner upper cover, and the inner lower cover is of a splayed structure and is in butt joint with the inner upper cover.

Description

Technical Field

[0001] This invention relates to the field of wafer manufacturing equipment technology, and in particular to a thermal radiation device for improving the crystallization rate of heavily doped red phosphorus single crystals. Background Technology

[0002] With the development and application of integrated circuit technology, especially the increasingly stringent requirements for low power consumption in power devices, there is a growing demand for single-crystal silicon substrates with lower resistivity. The solid solubility of dopants in silicon determines the limiting resistivity of this type of single-crystal substrate. Currently, the main dopants for N-type silicon single crystals in the industry are arsenic and antimony. However, the resistivity of the resulting single-crystal silicon after doping with arsenic and antimony does not meet the required standards. Since phosphorus has a higher solid solubility in the silicon lattice, single-crystal silicon with even lower resistivity can be obtained. Therefore, heavily phosphorus-doped silicon single crystals have emerged, and market demand is increasing. Next-generation silicon microwave power devices, Schottky devices, field-controlled high-frequency power electronic devices, and power integrated circuits require silicon single-crystal substrate materials with ultra-low resistivity (below 0.0011 Ω·cm).

[0003] Typically, both domestically and internationally, the resistivity of silicon single crystals has been reduced to approximately 0.0023 Ω·cm through heavy arsenic doping technology. If it could be further reduced by 0.0011 Ω·cm, the power consumption of devices on silicon substrates could be reduced by more than 20%. Therefore, Czochralski-grown silicon single crystals with even lower resistivity are urgently needed to reduce the power consumption of microelectronic devices and promote the development of the microelectronics industry. Theoretically, Czochralski-grown silicon can achieve even lower resistivity through heavy phosphorus doping, but this technology is very challenging and has remained an international problem. The following difficulties need to be overcome: high concentrations of phosphorus incorporated into the silicon melt lead to supercooling of the melt composition, making it difficult to achieve dislocation-free single crystal growth. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a thermal radiation device for improving the crystallization rate of heavily doped red phosphorus single crystals.

[0005] The technical objective of this invention is achieved as follows: a heat shield radiation device for improving the crystallization rate of heavily doped red phosphorus single crystals, comprising a support ring, an upper heat insulation material installed on the top of the support ring, and an outer heat shield assembly installed at the bottom of the support ring; The external heat shield assembly includes an outer heat shield cover and an inner heat shield cover. Both the outer and inner covers are annular structures and are connected to each other, forming a cavity in the middle. The cavity is filled with an inner heat insulation material. The inner heat shield consists of an upper inner cover, a lower inner cover, and an upper inner molybdenum cylinder. Both the upper inner cover and the upper inner molybdenum cylinder have a V-shaped structure. The upper inner molybdenum cylinder is located on the inner wall of the upper inner cover. The lower inner cover has a figure-eight structure and is connected to the upper inner cover.

[0006] Preferably, both the upper heat insulation material and the inner heat insulation material are made of cured carbon felt.

[0007] Preferably, the inner upper molybdenum cylinder is made of molybdenum plate.

[0008] Preferably, the purity of the molybdenum plate is 4N-5N.

[0009] Preferably, the support ring, the outer heat shield, the upper inner cover, and the lower inner cover are made of graphite.

[0010] The beneficial effects of this invention are: The bottom of the inner heat shield of this invention has an eight-shaped structure, which mainly serves to purge and guide the airflow on the surface of the melt. This allows the tiny particles generated by the volatilization of heavily doped red phosphorus to be effectively blown away from the upper part of the melt by the argon gas flow. Compared with the existing radiation heat shield structure with a flat bottom, it is less likely to accumulate oxides, reducing the probability of edge breakage and single crystal breakage during crystal pulling, and improving the single crystal formation rate. The inner upper molybdenum cylinder can increase the longitudinal temperature gradient of the crystal rod, increase the solid-liquid interface crystallization rate, further increase the pulling speed and reduce power consumption.

[0011] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the existing thermal field structure.

[0014] Figure 2 This is a schematic diagram of the structure of the thermal radiation device provided in an embodiment of the present invention.

[0015] Figure 3 This is a schematic diagram of the airflow direction of the thermal radiation device provided in an embodiment of the present invention.

[0016] Attached reference numerals: 1. Inner upper molybdenum cylinder; 2. Upper heat insulation material; 3. Support ring; 4. Heat shield outer cover; 5. Inner upper cover; 6. Inner heat insulation material; 7. Inner lower cover. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0018] This embodiment provides a heat shield radiation device for improving the crystallization rate of heavily doped red phosphorus single crystals. It comprises: an upper heat insulation material 2, a support ring 3, an outer heat shield cover 4, an inner heat insulation material 6, an inner upper cover 5, an inner upper molybdenum cylinder 1, and an inner lower cover 7. The support ring 3 serves as the mounting base, with the annular upper heat insulation material 2 mounted on its top and an outer heat shield assembly consisting of the outer heat shield cover 4, the inner heat shield cover, and the inner heat insulation material 6 mounted on its bottom. The inner heat shield cover is composed of the inner upper cover 5, the inner lower cover 7, and the inner upper molybdenum cylinder 1.

[0019] The outer heat shield cover 4 has a ring-shaped structure. The inner upper cover 5 and the inner upper molybdenum cylinder 1 are both inner V-shaped cones, and the inner upper molybdenum cylinder 1 is fixed to the inner wall of the inner upper cover 5. The inner lower cover 7 has a figure-eight ring-shaped structure, and the top of the inner lower cover 7 is connected to the bottom of the inner upper cover 5. The inner upper cover 5, the inner lower cover 7, and the outer heat shield cover 4 are connected together to form a cavity in the middle, and the inner heat insulation material 6 is installed in the cavity.

[0020] In this embodiment, the outer heat shield 4, inner heat shield 4, and inner heat insulation material 6 effectively enhance the lateral heat preservation effect, reducing the lateral temperature gradient and making it more conducive to single crystal pulling. The inner upper molybdenum cylinder 1 further utilizes the high temperature resistance, large heat capacity, and low thermal radiation of molybdenum to increase the longitudinal temperature gradient of the crystal rod, improve the solid-liquid interface crystallization rate, further increase the pulling speed, and reduce power consumption. This embodiment solves the problem of not being able to grow 12-inch 300mm heavily doped red phosphorus Czochralski silicon single crystals in ordinary standard single crystal thermal fields, making the growth of 12-inch 300mm heavily doped phosphorus Czochralski silicon single crystals as easy as 6-inch and 8-inch heavily doped Czochralski silicon single crystals, effectively improving the single crystal success rate.

[0021] This embodiment differs from ordinary thermal fields ( Figure 1 The main difference is that this embodiment adds an upper heat insulation material 2 and an inner heat insulation material 6, and changes the shape of the inner upper cover 5, the inner upper molybdenum cylinder 1, and the inner lower cover 7. The support ring 3, the outer heat shield cover 4, the inner upper cover 5, and the inner lower cover 7 are all made of high-purity graphite. The upper heat insulation material 2 and the inner heat insulation material 6 are both made of high-purity cured carbon felt. The inner upper molybdenum cylinder 1 is a molybdenum product, made of molybdenum sheet with a purity of 4N-5N.

[0022] Among them, the upper heat insulation material 2, the support ring 3, and the inner heat insulation material 6 mainly serve to support and insulate; the outer heat shield 4 and the inner upper cover 5 mainly serve to insulate and regulate the flow field above the melt; the inner lower cover 7 mainly serves to purge and guide the airflow on the surface of the melt. Figure 3This allows the tiny particles generated by the volatilization of heavily doped red phosphorus to be effectively blown away from the top of the melt by the argon gas flow. Because the bottom of the radiant heating screen has a figure-eight ring structure, compared to existing flat-bottomed radiant heating screen structures, it is less prone to oxide accumulation and can be quickly discharged from the top of the melt with the argon gas flow, reducing the possibility of falling into the silicon melt, reducing edge breakage during crystal pulling, lowering the probability of single crystal breakage, and increasing the single crystal formation rate. The principle is: 1. Airflow guidance and velocity control The upper V-shaped structure forms a gradually narrowing channel from top to bottom, which gradually increases the flow velocity of argon gas as it flows through this region (according to Bernoulli's principle, the flow velocity increases as the cross-sectional area decreases), thereby enhancing the ability to carry and purge volatiles (such as red phosphorus oxides) from the surface of the melt. The lower V-shaped structure: the opening expands downward to form a diffusion channel, which allows the airflow to diffuse and slow down rapidly after leaving the melt surface, avoiding airflow rebound or eddy current generation, thereby reducing the deposition of oxides at the lower edge of the heat shield; 2. Optimization of oxide discharge pathways The inclined inner wall of the figure-eight structure can guide the airflow to flow outward and downward, so that the argon gas carrying oxides naturally moves away from the center of the melt and prevents the oxides from falling back into the melt. This structure avoids the airflow stagnation zone that is easily formed under the traditional flat heat shield and reduces the adhesion and accumulation of oxides at the bottom of the heat shield.

[0023] The table below summarizes the relevant parameters of 10 12-doped red phosphorus silicon single crystals manufactured using a hot-screen radiation device for high crystallization rate of heavily doped red phosphorus single crystals. The resistivity of all single crystals in the table is less than 0.0013 Ω·cm, the oxygen concentration is 6.6-17.4 ppma, and the radial resistivity uniformity (RRG) is less than 10%. <100> Crystal orientation), oxygen content uniformity ORG less than 10% <100> (Crystal orientation), crystallization rate >58%.

[0024] The above description is merely a preferred embodiment of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A heat shield radiation device for improving the crystal growth rate of heavily doped red phosphorus single crystals, characterized by: Includes a support ring (3), an upper heat insulation material (2) installed on the top of the support ring, and an external heat shield assembly installed at the bottom of the support ring; The external heat shield assembly includes an outer heat shield cover (4) and an inner heat shield cover. Both the outer and inner covers are annular structures and are connected to each other, forming a cavity in the middle. The cavity is filled with an inner heat insulation material (6). The inner heat shield consists of an upper inner cover (5), a lower inner cover (7), and an upper inner molybdenum cylinder (1). Both the upper inner cover and the upper inner molybdenum cylinder are V-shaped structures. The upper inner molybdenum cylinder is located on the inner wall of the upper inner cover. The lower inner cover is a figure-eight structure and is connected to the upper inner cover.

2. The thermal radiation device for improving the crystallization rate of heavily doped red phosphorus single crystals according to claim 1, characterized in that: Both the upper thermal insulation material and the inner thermal insulation material are made of cured carbon felt.

3. The thermal radiation device for improving the crystallization rate of heavily doped red phosphorus single crystals according to claim 1, characterized in that: The inner upper molybdenum cylinder is made of molybdenum plate.

4. A thermal radiation device for improving the crystallization rate of heavily doped red phosphorus single crystals according to claim 3, characterized in that: The purity of the molybdenum plate is 4N-5N.

5. A thermal radiation device for improving the crystallization rate of heavily doped red phosphorus single crystals according to claim 1, characterized in that: The support ring, outer heat shield, upper inner cover, and lower inner cover are made of graphite.

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