Zone-melting silicon single crystal preparation device for detecting minority carrier lifetime of polycrystalline silicon

Abstract

The utility model discloses a zone-melting silicon single crystal preparation device for detecting minority carrier lifetime of polycrystalline silicon. The zone-melting silicon single crystal preparation device comprises a zone-melting furnace, and an upper shaft, a lower shaft, a sample core clamp, a coil and a seed crystal clamp which are arranged in the zone-melting furnace, wherein the upper end of the upper shaft and the lower end of the lower shaft are respectively fixed at the inner top and the inner bottom of the zone melting furnace, and the upper shaft and the lower shaft are respectively connected with a driving mechanism; a sample core clamp used for clamping and fixing a sample core is arranged at the lower end of the upper shaft, a seed crystal clamp used for clamping and fixing a seed crystal is arranged at the upper end of the lower shaft, and the sample core clamp and the seed crystal clamp are relatively and vertically arranged; the coil is arranged around the sample core and is connected with a heating mechanism. Therefore, the technical problem that dislocation cannot be eliminated thoroughly and extends to a single crystal can be avoided, and the minority carrier lifetime in a polycrystalline silicon product can be represented more accurately during detection.

Description

Technical Field

[0001] This utility model relates to the field of machinery, and in particular to a zone melting silicon single crystal preparation device for detecting minority carrier lifetime of polycrystalline silicon. Background Technology

[0002] The concentrations of carbon, oxygen, donor and acceptor impurities in polycrystalline silicon rods were measured using horizontal zone melting crystal pulling and spectral analysis. The measured donor and acceptor impurity concentrations could also be used to estimate the resistivity of granular polycrystalline silicon. At the same time, the minority carrier lifetime of the obtained silicon single crystal rods was measured on a minority carrier lifetime meter to determine whether the content of each impurity in the polycrystalline silicon material met the index requirements.

[0003] In the process of realizing this utility model, it was found that the crystal rods produced by the existing granular polycrystalline silicon zone melting method cannot accurately achieve dislocation-free crystals. Therefore, when the concentrations of carbon, oxygen, donor and acceptor impurities in the polycrystalline silicon rods are measured on a spectrometer and the minority carrier lifetime is measured on a minority carrier lifetime meter, the measured minority carrier lifetime is very low and cannot meet the index requirements. In other words, it is difficult to accurately characterize the minority carrier lifetime in polycrystalline silicon products. Utility Model Content

[0004] In view of this, the present invention provides a zone-melting silicon single crystal preparation device for detecting minority carrier lifetime in polycrystalline silicon. It can add a zone-melting silicon single crystal preparation device to the original horizontally pulled crystal rod. By eliminating the crystal-leading dislocations through the necking process in the suspended zone-melting silicon single crystal, it grows a dislocation-free silicon single crystal, thereby avoiding the technical problem that dislocations cannot be completely eliminated and extend to the single crystal. This enables more accurate characterization of minority carrier lifetime in polycrystalline silicon products during detection.

[0005] To achieve the above objectives, an embodiment of this utility model provides a zone-melting silicon single crystal preparation apparatus for detecting minority carrier lifetime in polycrystalline silicon, comprising: a zone melting furnace and an upper shaft, a lower shaft, a sample core clamp, a coil, and a seed crystal clamp placed within the zone melting furnace; wherein, the upper end of the upper shaft and the lower end of the lower shaft are respectively fixed to the inner top and inner bottom of the zone melting furnace, and the upper shaft and the lower shaft are respectively connected to a driving mechanism; the lower end of the upper shaft is provided with a sample core clamp for clamping and fixing the sample core, and the upper end of the lower shaft is provided with a seed crystal clamp for clamping and fixing the seed crystal, and the sample core clamp and the seed crystal clamp are arranged perpendicularly to each other; the coil is arranged around the sample core, and the coil is connected to a heating mechanism.

[0006] Optionally, the sample core fixture adopts a four-bar sleeve and is equipped with a circular ferrule.

[0007] Optionally, the seed crystal fixture includes a fixture body and a rotating ferrule connected to the fixture body.

[0008] Optionally, an inner square space is formed between the rotating sleeve and the fixture body, and the rotating sleeve is provided with bolts for fixing the seed crystal in the square space.

[0009] Optionally, the coil is a high-frequency induction coil.

[0010] Optionally, the high-frequency induction coil is duckbill shaped, designed with a thick outer layer and a thin inner layer, and is hollow, with built-in cooling circulating water.

[0011] One embodiment of the above-mentioned utility model has the following advantages or beneficial effects: This utility model provides a portable zone-melting silicon single crystal preparation device for detecting minority carrier lifetime in polycrystalline silicon. It realizes the pulling of granular polycrystalline silicon rods into zone-melting single crystals and the growth into dislocation-free silicon single crystals, thereby avoiding the incomplete elimination of dislocations and their extension into the single crystal. This allows the silicon single crystal rods to be measured on a spectrometer and a minority carrier lifetime meter to measure the concentration of carbon, oxygen, donor and acceptor impurities, minority carrier lifetime, etc. in the polycrystalline silicon rods, more accurately characterizing the content of various impurities and minority carrier lifetime of granular polycrystalline silicon materials. In particular, the measured minority carrier lifetime of granular polycrystalline silicon materials meets the index requirements, improving the accuracy of granular polycrystalline silicon product testing.

[0012] The further effects of the aforementioned unconventional alternative methods will be explained below in conjunction with specific implementation methods. Attached Figure Description

[0013] The accompanying drawings are provided to better understand this utility model and do not constitute an undue limitation thereof. Wherein:

[0014] Figure 1 This is a schematic diagram of a zone melting silicon single crystal preparation apparatus for detecting minority carrier lifetime of polycrystalline silicon according to an embodiment of the present invention. Detailed Implementation

[0015] The following description, in conjunction with the accompanying drawings, illustrates exemplary embodiments of the present invention, including various details to aid understanding. These embodiments should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0016] At least one embodiment of this utility model provides a zone-melting silicon single-crystal preparation apparatus for detecting minority carrier lifetime in polycrystalline silicon, wherein minority carrier lifetime is the average survival time of minority carriers in a semiconductor, and lifetime indicates the time it takes for minority carriers to decrease to their original value. Figure 1As shown, the zone melting silicon single crystal preparation apparatus for polycrystalline silicon minority carrier lifetime detection may include a zone melting furnace 1 and an upper shaft 11, a lower shaft 12, a sample core clamp 9, a coil 10, and a seed crystal clamp 2 placed inside the zone melting furnace 1. In an embodiment, the upper end of the upper shaft 11 and the lower end of the lower shaft 12 are respectively fixed to the inner top and inner bottom of the zone melting furnace 1, and the upper shaft 11 and the lower shaft 12 are respectively connected to a driving mechanism (examples include hydraulic drive, pneumatic drive, mechanical drive, etc., which are not limited here). The lower end of the upper shaft 11 is provided with a sample core clamp 9 for clamping and fixing the sample core 8, and the upper end of the lower shaft 12 is provided with a seed crystal clamp 2 for clamping and fixing the seed crystal 3, and the sample core clamp 9 and the seed crystal clamp 2 are arranged perpendicularly to each other. In addition, the coil 10 is arranged around the sample core 8, and the coil 10 is connected to a heating mechanism (examples include resistance heating, infrared heating, electromagnetic heating, etc., which are not limited here).

[0017] Example: In the use of a zone melting silicon single crystal preparation apparatus for polycrystalline silicon minority carrier lifetime testing, the zone melting furnace 1 can use a core sample holder 9 to hold and fix a core sample 8, and the zone melting furnace 1 can use a seed crystal holder 2 to hold and fix a seed crystal 3. The core sample 8 is heated by the coil 10 to form a melt 7, and the upper end of the seed crystal 3 can be gently and vertically immersed into the melt 7. Then, the seed crystal 3 is heated. By monitoring the color change of the seed crystal 3 (e.g., turning red), the power setting of the coil 10 is reduced, the lower shaft is pulled up, and it is slowly raised. Monitoring continues until obvious sharp corners appear on each of the four edges of the seed crystal 3 and the width of the melt zone is not greater than the width of the seed crystal, the neck 4 is reduced and the size Φ is controlled to be ≤3mm, and the length L is at least 30-40mm. Then, the upper shaft 11 and the lower shaft 12 are simultaneously pulled down by the drive mechanism. The speed of the upper shaft 11 is maintained at approximately 1.5 mm / min, while the speed of the lower shaft 12 is gradually increased to 15 mm / min. The power and the pulling speed of the upper shaft 11 are adjusted according to the state of the melt 7 to ensure the diameter of the neck 4 is stable, so that the solid-liquid line is in the middle position of the coil. The neck 4 is then pulled to a length of at least 30-40 mm using the diameter Φ at this point. Finally, the three growth lines of the silicon single crystal are monitored to ensure that the equal-diameter silicon single crystal rod 6 is a single crystal. <111> The necking length L reaches 30-40mm, and the shoulder is formed to create the shoulder 5 (shoulder diameter Φ10±1mm). The length is recorded again, and the silicon single crystal rod 6 is grown with constant diameter. The state of the melt 7 is monitored, and the power of the coil 10 is adjusted to maintain the temperature gradient of the thermal field basically unchanged. The silicon single crystal rod 6 is grown with constant diameter to the required length. The power of the coil 10 is reduced until the melt 7 separates from the silicon single crystal rod 6. The silicon single crystal rod is taken out, and the furnace is cleaned according to the procedure to complete the preparation of the silicon single crystal rod for this test.

[0018] As can be seen, the zone melting silicon single crystal preparation device of this invention for detecting minority carrier lifetime in polycrystalline silicon grows dislocation-free silicon single crystals through necking, shoulder expansion, constant diameter growth, and tailing, avoiding the incomplete elimination of dislocations and their extension into the single crystal. This allows for more accurate characterization of the minority carrier lifetime in polycrystalline silicon products during detection, ensuring that the minority carrier lifetime of the polycrystalline silicon material meets the required specifications, thus improving the accuracy of polycrystalline silicon product detection. Simultaneously, the silicon single crystal rod is used to measure the concentration of carbon, oxygen, donor and acceptor impurities, and minority carrier lifetime in the polycrystalline silicon rod using a spectrometer and a minority carrier lifetime meter, further accurately characterizing the impurity content and minority carrier lifetime of the polycrystalline silicon material.

[0019] In some other embodiments of this utility model, the sample core clamp 9 may employ a four-bar sleeve and be equipped with a circular retainer, thereby enabling the clamping and fixing of sample cores of different diameters by moving the circular retainer. In a preferred embodiment, the sample core clamp 9 clamps and fixes sample cores with a diameter in the range of 10-25mm.

[0020] In some further embodiments of this utility model, the seed crystal clamp 2 may include a clamp body and a rotating sleeve connected to the clamp body. Further, an inner square space is formed between the rotating sleeve and the clamp body, and the rotating sleeve is provided with bolts for fixing the seed crystal in the square space, so that the cuboid seed crystal is inserted into the inner square space formed by the rotating sleeve and the clamp body, and finally fixed by the bolts on the rotating sleeve. In a preferred embodiment, the seed crystal clamp 2 may be designed to be 4.5 cm high and 2 cm in diameter.

[0021] In some embodiments of this invention, coil 10 can be a high-frequency induction coil of a zone melting single crystal furnace. Further, coil 10 is duckbill-shaped, designed with a thick outer layer, a thin inner layer, and a hollow interior, housing cooling circulating water. Furthermore, this invention utilizes a suspended zone melting method, generating eddy currents in the sample core using a high-frequency magnetic field produced by the high-frequency induction coil under argon protection. Due to the eddy currents, a zone melting zone is generated near the high-frequency induction coil on the sample core. A driving mechanism brings the sample core melting zone of the upper shaft 11 into contact with the seed crystal (5*5*60mm) and transfers heat to the seed crystal until the upper and lower melting zones reach a molten state. This process involves necking, dislocation removal, and pulling a zone melting single crystal.

[0022] In summary, the zone-melting silicon single crystal preparation device for minority carrier lifetime testing of polycrystalline silicon of this invention can pull granular polycrystalline silicon rods into zone-melting single crystals, and control the necking size Φ to ≤3mm and the length L to 30-40mm to eliminate seed dislocations and grow dislocation-free silicon single crystals, avoiding the incomplete elimination of dislocations and their extension into the single crystal. The minority carrier lifetime of the granular polycrystalline silicon material measured all meet the index requirements, improving the accuracy of polycrystalline silicon product testing.

[0023] Unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," etc., can refer to fixed connections, detachable connections, or integral connections. Those skilled in the art can understand the specific meaning of these terms in this utility model based on the specific circumstances.

[0024] The specific embodiments described above do not constitute a limitation on the scope of protection of this utility model. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can occur depending on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A zone-melting silicon single crystal preparation apparatus for detecting minority carrier lifetime in polycrystalline silicon, characterized in that, include: A zone melting furnace and an upper shaft, a lower shaft, a core sample holder, a coil, and a seed crystal holder placed inside the zone melting furnace; The upper end of the upper shaft and the lower end of the lower shaft are respectively fixed to the inner top and inner bottom of the zone melting furnace, and the upper shaft and the lower shaft are respectively connected to a drive mechanism; The lower end of the upper shaft is provided with a core clamp for holding and fixing the core sample, and the upper end of the lower shaft is provided with a seed crystal clamp for holding and fixing the seed crystal. The core clamp and the seed crystal clamp are arranged perpendicularly to each other. The coil is arranged around the sample core, and the coil is connected to a heating mechanism.

2. The apparatus for preparing a silicon single crystal by the zone melting method for detecting a lifetime of a minority carrier of polysilicon according to claim 1, wherein include: The sample core fixture uses a four-bar sleeve and is equipped with a circular ferrule.

3. The apparatus for preparing a zone-melted silicon single crystal for detection of polysilicon minority carrier lifetime according to claim 1, wherein include: The seed crystal fixture includes a fixture body and a rotating ferrule connected to the fixture body.

4. The apparatus for preparing a zone-melted silicon single crystal for detection of polysilicon minority carrier lifetime according to claim 3, wherein include: The rotating sleeve and the fixture body form an inner square space, and the rotating sleeve is provided with bolts for fixing the seed crystal in the square space.

5. The apparatus for preparing a silicon single crystal by the zone melting method for detecting a lifetime of a minority carrier of polysilicon according to claim 1, wherein include: The coil is a high-frequency induction coil.

6. The zone melting silicon single crystal preparation apparatus for detecting minority carrier lifetime in polycrystalline silicon according to claim 5, characterized in that, The high-frequency induction coil is duckbill shaped, designed with a thick outer layer and a thin inner layer, and is hollow with built-in cooling circulating water.

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