Quartz crucible and production method thereof

Abstract

The quartz crucible comprises a transparent layer and a bubble layer, the transparent layer is sleeved with the bubble layer, the transparent layer comprises a first straight wall part and a first arc bottom part, the bubble layer comprises a second straight wall part and a second arc bottom part, and the joints of all the parts are in solidification connection through a high-purity quartz solution. The invention relates to the technical field of quartz crucible production. According to the quartz crucible and the production method thereof, the transparent layer and the bubble layer are prefabricated under the independent vacuum condition respectively, the transparent layer and the bubble layer are filled and connected through the high-temperature and high-purity quartz solution, integrated forming of a double-layer structure is achieved, the interlayer impurity pollution risk is eliminated, the transparent layer is subjected to electric arc melting under the condition that the vacuum degree is larger than or equal to 0 and smaller than or equal to 0.5 MPa, and the bubble layer is formed under the air or micro-negative pressure condition; in consideration of the requirements of low bubble rate and high bubble strength of the transparent layer, the transparent layer adopts a segmented structure of a straight wall part and an arc bottom part, and the arc bottom part is further subdivided into an arc part and a bottom part to ensure that no microscopic bubble remains in a silicon liquid contact area.

Description

Technical Field

[0001] The invention relates to the technical field of quartz crucible production, in particular to a quartz crucible and a production method thereof. Background Art

[0002] Quartz crucible has the advantages of high purity, strong temperature resistance, large size and high precision, good thermal insulation, energy saving, stable quality, etc. It is used more and more widely. The detection of quartz crucible is a very important link, and the detection of quartz crucible is developing towards on-site detection. Quartz crucible can be used below 1450 degrees and is divided into transparent and opaque types. The translucent quartz crucible made by arc method is an indispensable basic material for pulling large-diameter single crystal silicon and developing large-scale integrated circuits. Today, the world's semiconductor industry developed countries have replaced small transparent quartz crucibles with this crucible. It has the advantages of high purity, strong temperature resistance, large size and high precision, good thermal insulation, energy saving, stable quality, etc.

[0003] Traditional double-layer quartz crucibles have the following technical bottlenecks:

[0004] 1. Insufficient interlayer bonding strength:

[0005] The nested structure relies on graphite glue or carbon fiber ropes for connection, which are prone to oxidative decomposition at temperatures above 1500°C, leading to interlayer delamination and silicon rod breakage. Traditional nested crucibles experience an interlayer delamination rate of 12% after 180 hours of crystal pulling, increasing the cost per furnace by 30%.

[0006] 2. Low bubble control accuracy:

[0007] Molding under a single vacuum environment results in a bubble residual rate of up to 1.2 bubbles / cm in the transparent layer 2 , directly affecting the minority carrier lifetime of silicon rods (<10μs); the density gradient of the bubble layer is uncontrollable, the outer bubble diameter is >3mm, the inner bubble diameter is >1mm, and the thermal shock resistance is poor;

[0008] 3. Risk of impurity contamination:

[0009] Alkali metal impurities such as Li, Na, and K are easily introduced into the nested joints, causing the resistivity of the silicon rod to fluctuate by more than 15%, affecting the performance of semiconductor devices. Summary of the Invention

[0010] In view of the deficiencies in the prior art, the present invention provides a quartz crucible and a production method thereof, which solve the problems raised in the above background technology.

[0011] To achieve the above objectives, the present invention is implemented through the following technical solutions: a quartz crucible, including a transparent layer and a bubble layer, the bubble layer is sleeved on the outside of the transparent layer, the transparent layer includes a first straight wall portion and a first arc bottom, the bubble layer includes a second straight wall portion and a second arc bottom, and the joints of each part are solidified and connected by high-purity quartz solution.

[0012] Preferably, the transparent layer and the bubble layer are connected by filling and solidifying with a high-temperature high-purity quartz solution.

[0013] Preferably, the first arc bottom includes a first arc portion and a first bottom, and the second arc bottom includes a second arc portion and a second bottom. The connection between each arc portion and the bottom, and between the straight wall portion and the arc portion are filled and solidified with high-purity quartz solution.

[0014] Preferably, the SiO2 content of the high-purity quartz solution is ≥99.9%, and the viscosity is ≤0.1 Pa·s at 1800°C, ensuring that no bubbles remain in the filling layer.

[0015] The present invention also discloses a method for producing a quartz crucible, which specifically comprises the following steps:

[0016] S1: Under the condition of 0≤vacuum≤0.5MPa, use arc heat release to melt the inner layer of quartz sand to obtain a transparent layer preform;

[0017] S2: Under a slightly negative pressure (≤-0.05MPa), an arc is used to heat the outer layer of quartz sand to obtain a bubble layer preform;

[0018] S3: Assemble the transparent layer preform and the bubble layer preform into a dedicated mold, inject 1700°C high-purity quartz solution, fill the gap until the liquid level is 10 mm above the crucible mouth, keep the temperature at 1600°C for 2 hours to completely solidify the filling layer, and then cool to room temperature at a rate of 5°C / min;

[0019] S4: Grind the solidified crucible to ensure that the surface roughness of each connection part is Ra ≤ 0.8 μm;

[0020] S5: Use laser confocal microscopy to detect the bubble density in the transparent layer, which should be ≤0.5 / cm 2 The alkali metal impurities were detected by ICP-MS to ensure that the content of Li, Na, and K was ≤0.1ppbw. The crucible deformation was ≤0.5mm after a 300-hour thermal cycle test at 1500℃.

[0021] Preferably, the purity of the inner layer quartz sand is ≥4N8 (≥99.998%), the purity of the outer layer quartz sand is ≥4N5 (≥99.995%), and the Al2O3 content in the outer layer quartz sand is ≤50ppm, so as to control the crystallization rate of the bubble layer.

[0022] Preferably, the transparent layer is arc-melted under a vacuum of 0.3 MPa, with a current of 2000 A and a melting time of 15 minutes, and a bubble density of ≤0.5 / cm 2 The bubble layer is formed under a slight negative pressure (-0.03MPa), the current is 1800A, the melting time is 20 minutes, and the flexural strength is ≥30MPa.

[0023] Preferably, the preparation of the raw materials specifically includes the following steps:

[0024] A1, inner layer sand: Unimin IOTA-STD quartz sand, purity 99.9992%, particle size distribution D50 = 150μm;

[0025] A2, outer layer sand: TQC AQ-3 quartz sand, purity 99.995%, particle size distribution D50 = 300μm;

[0026] A3. Connecting solution: Mix high-purity quartz powder (SiO2 ≥ 99.99%) and deionized water in a mass ratio of 3:7, add 0.5wt% polyvinyl butyral (PVB) as a binder, and melt at 1500°C to prepare the solution.

[0027] Preferably, the transparent layer prefabrication specifically includes the following steps:

[0028] B1. Evenly spread the inner layer of sand on the inner wall of the rotating mold with a thickness of 3.5mm;

[0029] B2. Arc melting at a current of 2000A for 15 minutes under a vacuum degree of 0.3 MPa to form a transparent layer preform;

[0030] B3. Use a diamond grinding head to grind the bottom of the straight wall and the top of the arc bottom of the preform to remove the oxide layer.

[0031] Preferably, the bubble layer prefabrication specifically includes the following steps:

[0032] C1. Fill the outer layer of sand to the outer layer of the mold, with a thickness of 8mm;

[0033] C2. Arc melting at a current of 1800A for 20 minutes under a slight negative pressure of -0.03MPa to form a bubble layer preform;

[0034] C3. Sandblast the prefabricated body to remove loose sand on the surface.

[0035] Beneficial effects

[0036] The present invention provides a quartz crucible and a production method thereof. Compared with the prior art, the quartz crucible and the production method thereof have the following advantages: the quartz crucible and the production method thereof are provided with a bubble layer sleeved on the outside of a transparent layer, the transparent layer includes a first straight wall portion and a first arc bottom portion, the bubble layer includes a second straight wall portion and a second arc bottom portion, the joints of each portion are solidified and connected by a high-purity quartz solution, the transparent layer and the bubble layer are filled and solidified by a high-temperature high-purity quartz solution, the first arc bottom portion includes a first arc portion and a first bottom portion, the second arc bottom portion includes a second arc portion and a second bottom portion, the joints between each arc portion and the bottom portion, and between the straight wall portion and the arc portion are filled and solidified by a high-purity quartz solution, the transparent layer and the bubble layer are prefabricated under independent vacuum conditions, and are filled and connected by a high-temperature high-purity quartz solution, thereby realizing the integrated molding of a double-layer structure. To eliminate the risk of interlayer impurity contamination, the transparent layer is arc-melted under a vacuum degree of 0≤≤0.5MPa, and the bubble layer is formed in air or slightly negative pressure conditions, taking into account both the low bubble rate of the transparent layer and the high strength requirements of the bubble layer. The transparent layer adopts a "straight wall + arc bottom" segmented structure, and the arc bottom is further subdivided into the arc part and the bottom to ensure that there are no microscopic bubbles remaining in the contact area with the silicon liquid. The bubble layer adopts a gradient density design, with the outer bubble diameter ≤2mm and the inner bubble diameter ≤0.5mm, which improves the crucible's thermal shock resistance. Through high-purity quartz solution connection technology, the risk of interlayer impurity contamination is reduced, and the silicon rod scrap rate caused by interlayer impurities is reduced. The gradient density bubble layer design improves the crucible's thermal shock resistance to meet high-precision crystal pulling requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a flow chart of the steps of the present invention. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] See also Figure 1 The present invention provides a technical solution: a quartz crucible, comprising a transparent layer and a bubble layer, the bubble layer is sleeved on the outside of the transparent layer, the transparent layer comprises a first straight wall portion and a first arc bottom, the bubble layer comprises a second straight wall portion and a second arc bottom, and the joints of each part are solidified and connected by high-purity quartz solution.

[0040] In the present invention, the transparent layer and the bubble layer are filled with a high-temperature high-purity quartz solution and then solidified and connected.

[0041] In the present invention, the first arc bottom includes a first arc portion and a first bottom, and the second arc bottom includes a second arc portion and a second bottom. The connections between each arc portion and the bottom, and between the straight wall portion and the arc portion are filled and solidified with high-purity quartz solution.

[0042] In the present invention, the SiO2 content of the high-purity quartz solution is ≥99.9%, and the viscosity is ≤0.1 Pa·s at 1800° C., ensuring that no bubbles remain in the filling layer.

[0043] The present invention also discloses a method for producing a quartz crucible, which specifically comprises the following steps:

[0044] S1: Under the condition of 0≤vacuum≤0.5MPa, use arc heat release to melt the inner layer of quartz sand to obtain a transparent layer preform;

[0045] S2: Under a slightly negative pressure (≤-0.05MPa), an arc is used to heat the outer layer of quartz sand to obtain a bubble layer preform;

[0046] S3: Assemble the transparent layer preform and the bubble layer preform into a dedicated mold, inject 1700°C high-purity quartz solution, fill the gap until the liquid level is 10 mm above the crucible mouth, keep the temperature at 1600°C for 2 hours to completely solidify the filling layer, and then cool to room temperature at a rate of 5°C / min;

[0047] S4: Grind the solidified crucible to ensure that the surface roughness of each connection part is Ra ≤ 0.8 μm;

[0048] S5: Use laser confocal microscopy to detect the bubble density in the transparent layer, which should be ≤0.5 / cm 2 The alkali metal impurities were detected by ICP-MS to ensure that the content of Li, Na, and K was ≤0.1ppbw. The crucible deformation was ≤0.5mm after a 300-hour thermal cycle test at 1500℃.

[0049] In the present invention, the purity of the inner quartz sand is ≥4N8 (≥99.998%), the purity of the outer quartz sand is ≥4N5 (≥99.995%), and the Al2O3 content in the outer quartz sand is ≤50ppm to control the crystallization rate of the bubble layer.

[0050] In the present invention, the transparent layer is arc-melted under a vacuum of 0.3 MPa, with a current of 2000 A and a melting time of 15 minutes, and a bubble density of ≤0.5 / cm 2 The bubble layer is formed under a slight negative pressure (-0.03MPa), the current is 1800A, the melting time is 20 minutes, and the flexural strength is ≥30MPa.

[0051] In the present invention, the preparation of raw materials specifically comprises the following steps:

[0052] A1, inner layer sand: Unimin IOTA-STD quartz sand, purity 99.9992%, particle size distribution D50 = 150μm;

[0053] A2, outer layer sand: TQC AQ-3 quartz sand, purity 99.995%, particle size distribution D50 = 300μm;

[0054] A3. Connecting solution: Mix high-purity quartz powder (SiO2 ≥ 99.99%) and deionized water in a mass ratio of 3:7, add 0.5wt% polyvinyl butyral (PVB) as a binder, and melt at 1500°C to prepare the solution.

[0055] In the present invention, the transparent layer prefabrication specifically includes the following steps:

[0056] B1. Evenly spread the inner layer of sand on the inner wall of the rotating mold with a thickness of 3.5mm;

[0057] B2. Arc melting at a current of 2000A for 15 minutes under a vacuum degree of 0.3 MPa to form a transparent layer preform;

[0058] B3. Use a diamond grinding head to grind the bottom of the straight wall and the top of the arc bottom of the preform to remove the oxide layer.

[0059] In the present invention, the bubble layer prefabrication specifically includes the following steps:

[0060] C1. Fill the outer layer of sand to the outer layer of the mold, with a thickness of 8mm;

[0061] C2. Arc melting at a current of 1800A for 20 minutes under a slight negative pressure of -0.03MPa to form a bubble layer preform;

[0062] C3. Sandblast the prefabricated body to remove loose sand on the surface.

[0063] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0064] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0065] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A quartz crucible comprising a transparent layer and a bubble layer, characterized in that: The bubble layer is sleeved on the outside of the transparent layer. The transparent layer includes a first straight wall portion and a first arc bottom. The bubble layer includes a second straight wall portion and a second arc bottom. The joints of each part are solidified by high-purity quartz solution.

2. A quartz crucible according to claim 1, characterized in that: The transparent layer and the bubble layer are filled with a high-temperature high-purity quartz solution and are solidified and connected.

3. The quartz crucible according to claim 1, wherein: The first arc bottom includes a first arc portion and a first bottom, and the second arc bottom includes a second arc portion and a second bottom. The connection between each arc portion and the bottom, and between the straight wall portion and the arc portion are filled and solidified with high-purity quartz solution.

4. The quartz crucible according to claim 1, wherein: The SiO2 content of the high-purity quartz solution is ≥99.9%, and the viscosity is ≤0.1 Pa·s at 1800° C., ensuring that no bubbles remain in the filling layer.

5. A quartz crucible according to claims 1-4, characterized in that: Its production method specifically comprises the following steps: S1: Under the condition of 0≤vacuum≤0.5MPa, use arc heat release to melt the inner layer of quartz sand to obtain a transparent layer preform; S2: Under a slightly negative pressure (≤-0.05MPa), an arc is used to heat the outer layer of quartz sand to obtain a bubble layer preform; S3: Assemble the transparent layer preform and the bubble layer preform into a dedicated mold, inject 1700°C high-purity quartz solution, fill the gap until the liquid level is 10 mm above the crucible mouth, keep the temperature at 1600°C for 2 hours to completely solidify the filling layer, and then cool to room temperature at a rate of 5°C / min; S4: Grind the solidified crucible to ensure that the surface roughness of each connection part is Ra ≤ 0.8 μm; S5: Use laser confocal microscopy to detect the bubble density in the transparent layer, which should be ≤0.5 / cm 2 The alkali metal impurities were detected by ICP-MS to ensure that the content of Li, Na, and K was ≤0.1ppbw. The crucible deformation was ≤0.5mm after a 300-hour thermal cycle test at 1500℃.

6. The method for producing a quartz crucible according to claim 5, wherein: The purity of the inner layer quartz sand is ≥4N8 (≥99.998%), the purity of the outer layer quartz sand is ≥4N5 (≥99.995%), and the Al2O3 content in the outer layer quartz sand is ≤50ppm, so as to control the crystallization rate of the bubble layer.

7. The method for producing a quartz crucible according to claim 5, wherein: The transparent layer is arc-melted under a vacuum degree of 0.3 MPa, with a current of 2000 A and a melting time of 15 minutes, and a bubble density of ≤0.5 / cm 2 The bubble layer is formed under a slight negative pressure (-0.03MPa), the current is 1800A, the melting time is 20 minutes, and the flexural strength is ≥30MPa.

8. The method for producing a quartz crucible according to claim 5, wherein: The preparation of the raw materials specifically comprises the following steps: A1, inner layer sand: Unimin IOTA-STD quartz sand, purity 99.9992%, particle size distribution D50 = 150μm; A2, outer layer sand: TQC AQ-3 quartz sand, purity 99.995%, particle size distribution D50 = 300μm; A3. Connecting solution: Mix high-purity quartz powder (SiO2 ≥ 99.99%) and deionized water in a mass ratio of 3:7, add 0.5wt% polyvinyl butyral (PVB) as a binder, and melt at 1500°C to prepare the solution.

9. The method for producing a quartz crucible according to claim 5, wherein: The transparent layer prefabrication specifically includes the following steps: B1. Evenly spread the inner layer of sand on the inner wall of the rotating mold with a thickness of 3.5mm; B2. Arc melting at a current of 2000A for 15 minutes under a vacuum degree of 0.3 MPa to form a transparent layer preform; B3. Use a diamond grinding head to grind the bottom of the straight wall and the top of the arc bottom of the preform to remove the oxide layer.

10. The method for producing a quartz crucible according to claim 5, wherein: The bubble layer prefabrication specifically comprises the following steps: C1. Fill the outer layer of sand to the outer layer of the mold, with a thickness of 8mm; C2. Arc melting at a current of 1800A for 20 minutes under a slight negative pressure of -0.03MPa to form a bubble layer preform; C3. Sandblast the prefabricated body to remove loose sand on the surface.

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