A system and method for measuring crystal quality during liquid phase silicon carbide crystal growth

Abstract

The invention discloses a system for measuring the crystal quality during the growth of silicon carbide crystals by a liquid phase method, comprising a crucible provided with a liquid raw material, a graphite disk, and a graphite disk driving device for driving the graphite disk to move up and down, a growing crystal seed crystal is arranged below the graphite disk, the seed crystal or the crystal is always in contact with the liquid raw material, a first electrically connected conductive rod is arranged above the graphite disk, a second electrically connected conductive rod is arranged below the crucible, a resistance detection module is used to detect the resistance between the two conductive rods in real time, a data acquisition module is used to collect displacement data of the graphite disk movement, a calculation module is used to calculate the quality of the crystal, and a display module is used to display the quality of the crystal in real time. The conductive rod is electrically connected to the graphite disk, and the resistance between the conductive rods is measured in real time, so that the resistance is converted into the quality of the silicon carbide crystal growth process, and displayed in real time, which helps the operator to observe in real time whether the growth of the silicon carbide crystal meets the requirements, and the displayed silicon carbide crystal growth quality is relatively accurate.

Description

Technical Field

[0001] The invention relates to a semiconductor crystal growth auxiliary system, and in particular to a system and method for measuring crystal quality during silicon carbide crystal growth using a liquid phase method. Background Art

[0002] Silicon carbide crystal growth is carried out in an almost completely closed graphite crucible, and the actual growth state of silicon carbide cannot be observed. In addition, since the actual growth speed of silicon carbide crystals is very slow and the mass change rate is very small, when relying on conventional weighing methods to consider its growth state, firstly, the weighing error will affect the detection of the crystal mass change rate, and secondly, its mass change rate is very small and is easily affected by external interference, such as furnace pressure changes, airflow fluctuations, detection element accuracy, and the silicon carbide wafer mass ratio in the entire load is too low. At present, there is no effective solution for the detection of silicon carbide crystal growth state (i.e., measuring the real-time thickness of the diaphragm during the silicon carbide growth process). Summary of the invention

[0003] Purpose of the invention: In view of the above shortcomings, the present invention provides a system for measuring the crystal quality of silicon carbide crystal growth by the liquid phase method, which displays data in real time.

[0004] The invention also provides a method for measuring crystal quality during silicon carbide crystal growth by a liquid phase method.

[0005] Technical solution: To solve the above problems, the present invention adopts a crystal quality measurement system during silicon carbide crystal growth by a liquid phase method, comprising a crucible, a graphite disk and a graphite disk driving device for driving the graphite disk to move up and down, wherein a liquid raw material is arranged in the crucible, a seed crystal is arranged below the graphite disk, and the silicon carbide crystal grows on the seed crystal, and the seed crystal or the silicon carbide crystal is always in contact with the liquid raw material. The system also comprises a data acquisition module, a resistance detection module, a calculation module and a display module, wherein a first conductive rod is arranged above the graphite disk, and the first conductive rod is electrically connected to the graphite disk, a second conductive rod is arranged below the crucible, and the second conductive rod is electrically connected to the crucible, the resistance detection module is used to detect the resistance between the first conductive rod and the second conductive rod in real time, the data acquisition module is used to collect displacement data of the graphite disk movement, the calculation module is used to calculate the quality of the silicon carbide crystal according to the resistance detected by the resistance detection module and the collected displacement data, and the display module is used to display the quality of the silicon carbide crystal obtained by the calculation module in real time.

[0006] Furthermore, the first conductive rod and the second conductive rod are both made of graphite material.

[0007] The present invention also adopts a method for measuring crystal quality during silicon carbide crystal growth by a liquid phase method, comprising the following steps:

[0008] (1) Detect and obtain the total resistance of the system when the crystal is not grown;

[0009] (2) growing silicon carbide crystals, moving the graphite disk, measuring the real-time resistance between the first conductive rod and the second conductive rod, and collecting displacement data of the graphite disk;

[0010] (3) Calculating the resistance of the crystal at this time based on the real-time resistance value, the total resistance value of the device, and the displacement data of the graphite disk;

[0011] (4) Calculating the crystal quality based on the resistivity of the crystal and the obtained crystal resistance;

[0012] (5) Real-time display of calculated crystal quality.

[0013] Furthermore, in step (1), the total resistance R 总0 The calculation formula is:

[0014] R 总0 =R 系统 +R 原料1 +R 籽晶1

[0015] Among them, R 系统 is the total resistance of the first conductive rod, the second conductive rod, the graphite disk and the crucible, R 原料1 is the resistance of the liquid raw material in the crucible, R 籽晶1 is the resistance value of the seed crystal placed under the graphite disk.

[0016] Furthermore, the crystal resistance R in step (3) is 晶体 The calculation formula is:

[0017] R 总 =R 总0 +R 晶体 +ΔR 原料

[0018] Among them, R 总 is the real-time resistance between the first conductive rod and the second conductive rod, ΔR 原料 is the change in resistance of the liquid material.

[0019] Furthermore, the resistance R 晶体 The calculation formula is:

[0020]

[0021] Among them, ρ 晶体 is the resistivity of the crystal, L 晶体 is the elongation length of the crystal, S 晶体 is the cross-sectional area of ​​the crystal;

[0022] The ΔR 原料 The calculation formula is:

[0023]

[0024] Among them, ρ 原料 The resistivity of the liquid material is ΔL 原料 is the length change of liquid raw material, S 原料 is the cross-sectional area of ​​the liquid raw material;

[0025] The graphite disk displacement distance L 石墨盘 The calculation formula is:

[0026] L 石墨盘 =L 晶体 +ΔL 原料 .

[0027] Furthermore, the calculation formula of the crystal mass m in step (4) is:

[0028] m=m 籽晶 +ε·S 晶体 ·L 晶体

[0029] Among them, m 籽晶 is the mass of the seed crystal, and ε is the density of the crystal.

[0030] Beneficial effect: Compared with the prior art, the significant advantage of the present invention is that the conductive rod is electrically connected to the graphite disk, and the resistance between the conductive rods is measured in real time, the resistance is converted into the mass of the silicon carbide crystal during the growth process, and the real-time display is helpful for the operator to observe in real time whether the growth of the silicon carbide crystal meets the requirements, avoid many influencing factors brought by the weighing method, and the displayed silicon carbide crystal growth quality is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the structure of the seed crystal and the graphite disk being connected at the beginning of the measurement method of the present invention;

[0032] Figure 2 This is a schematic diagram of the structure of the connection between the crystal and the graphite disk during crystal growth in the measurement method of the present invention. DETAILED DESCRIPTION

[0033] Example 1

[0034] like Figure 1 and Figure 2As shown, a system for measuring the thickness of a crystal during the growth of silicon carbide crystals by a liquid phase method in this embodiment includes a first conductive rod 1, a second conductive rod 5, a graphite disk 2, a crucible 4, a seed crystal 6, a resistance detection module 7, a graphite disk driving device, a calculation module and a display module. Liquid raw material is arranged in the crucible 4, a seed crystal 6 is arranged under the graphite disk 2, and a silicon carbide crystal 8 grows on the seed crystal 6. The graphite disk driving device drives the graphite disk 2 to move up and down to ensure that the seed crystal 6 or the silicon carbide crystal 8 is always in contact with the liquid raw material 3.

[0035] A first conductive rod 1 is arranged above the graphite disk 2, and a second conductive rod 5 is arranged below the crucible 4. In this embodiment, the first conductive rod 1 and the second conductive rod 5 are both made of graphite material. The first conductive rod 1 is electrically connected to the graphite disk 2, and the graphite disk 2 is electrically connected to the seed crystal 6, the silicon carbide crystal 8, the liquid raw material 3 and the crucible 4. The crucible 4 is electrically connected to the second conductive rod 5. The first conductive rod 1 and the second conductive rod 5 are respectively used as the input end and the output end of the circuit. The resistance between the first conductive rod 1 and the second conductive rod 5 is detected in real time by the resistance detection module 7, and the calculation module calculates the mass of the silicon carbide crystal 8 according to the resistance detected by the resistance detection module. Before crystal growth, the resistance detection module 7 detects the total resistance value of the first conductive rod 1, the graphite disk 2, the seed crystal 6, the liquid raw material 3, the crucible 4, and the second conductive rod; during crystal growth, the calculation module obtains the resistance of the crystal according to the real-time total resistance value of the system detected by the resistance detection module, the resistance value of the initial system calculated in advance, and the length change of the crystal and the liquid raw material, thereby obtaining the mass of the silicon carbide crystal. The display module is used to display the silicon carbide crystal quality obtained by the calculation module in real time, and the operator can make real-time adjustments to the process according to the data displayed by the display module.

[0036] Example 2

[0037] In this embodiment, a method for measuring the crystal quality of silicon carbide crystal growth by a liquid phase method is used, and the measurement system in the above embodiment is used for measurement. The measurement system is not described in detail here. The measurement method includes the following steps:

[0038] (1) Detect the total resistance of the system when it is not grown; the total resistance R 总0 The calculation formula is:

[0039] R 总0 =R 系统 +R 原料1 +R 籽晶1

[0040] Among them, R 系统 is the total resistance of the first conductive rod, the second conductive rod, the graphite plate and the crucible, and the total resistance of the system is R 系统 is a constant value and will not change during the silicon carbide crystal growth process; R 原料1 is the resistance of the liquid raw material in the crucible; R 籽晶1The resistance value of the seed crystal set under the graphite disk can be pre-measured by the equipment before crystal growth.

[0041] (2) Silicon carbide crystal growth is performed. During the crystal growth process, the liquid raw material is consumed and the silicon carbide crystal becomes longer. As the silicon carbide crystal becomes longer, the graphite disk is moved to ensure that the silicon carbide crystal is always in contact with the liquid raw material. The real-time resistance value R between the first conductive rod and the second conductive rod is measured. 总 , collect the displacement data L of the graphite disk 石墨盘 ;

[0042] (3) The resistance of the crystal at this time is calculated based on the real-time resistance value, the total resistance value of the device, and the displacement data of the graphite disk; the crystal resistance value R 晶体 The calculation formula is:

[0043] R 总 =R 总0 +R 晶体 +ΔR 原料

[0044] Among them, R 总 is the real-time resistance between the first conductive rod and the second conductive rod, ΔR 原料 is the change in resistance of the liquid material.

[0045] And the resistance value R 晶体 The calculation formula is:

[0046]

[0047] Among them, ρ 晶体 is the resistivity of the crystal, L 晶体 is the elongation length of the crystal, S 晶体 is the cross-sectional area of ​​the crystal;

[0048] ΔR 原料 The calculation formula is:

[0049]

[0050] Among them, ρ 原料 The resistivity of the liquid material is ΔL 原料 is the length change of liquid raw material, S 原料 is the cross-sectional area of ​​the liquid raw material;

[0051] Graphite disk displacement distance L 石墨盘 The calculation formula is:

[0052] L 石墨盘 =L 晶体 +ΔL 原料

[0053] The elongation length of the crystal is obtained as:

[0054] (4) The crystal mass is calculated based on the resistivity of the crystal and the obtained crystal resistance; the calculation formula of the crystal mass m is:

[0055] m=m 籽晶 +ε·S 晶体 ·L 晶体

[0056] Among them, m 籽晶 is the mass of the seed crystal, and ε is the density of the crystal.

[0057] The mass of the crystal obtained is:

[0058] Among them, m 籽晶 ,ε,S 晶体 , 晶体 , S 原料 , 原料 These are parameters that can be measured in advance by the equipment. 总0 is the total resistance measured in the initial state, so the total resistance R of the current system is detected in real time 总 and graphite disk displacement distance L 石墨盘 , the mass m of the current crystal can be calculated.

[0059] (5) The calculated crystal mass m is displayed in real time, which helps the operator to observe in real time whether the growth of the silicon carbide crystal meets the requirements, avoids many influencing factors brought by the weighing method, and displays the growth quality of the silicon carbide crystal more accurately.

Claims

1. A system for measuring crystal quality during silicon carbide crystal growth by a liquid phase method, comprising a crucible (4), a graphite disk (2), and a graphite disk driving device for driving the graphite disk (2) to move up and down, wherein a liquid raw material (3) is arranged in the crucible (4), a seed crystal (6) is arranged below the graphite disk (2), a silicon carbide crystal (8) grows on the seed crystal (6), and the seed crystal (6) or the silicon carbide crystal (8) is always in contact with the liquid raw material (3), characterized in that: The invention also comprises a data acquisition module, a resistance detection module (7), a calculation module and a display module. A first conductive rod (1) is arranged above the graphite disk (2), and the first conductive rod (1) is electrically connected to the graphite disk (2). A second conductive rod (5) is arranged below the crucible (4), and the second conductive rod (5) is electrically connected to the crucible. The resistance detection module is used to detect the resistance between the first conductive rod (1) and the second conductive rod (5) in real time. The data acquisition module is used to collect displacement data of the graphite disk (2). Before crystal growth, the resistance detection module (7) ) detects the total resistance value of the first conductive rod (1), the graphite disk (2), the seed crystal (6), the liquid raw material (3), the crucible (4), and the second conductive rod; during crystal growth, the calculation module obtains the resistance of the silicon carbide crystal based on the real-time resistance detected by the resistance detection module and the total resistance value of the initial system calculated in advance and the displacement data of the graphite disk (2), and calculates the mass of the silicon carbide crystal based on the resistivity of the silicon carbide crystal and the obtained resistance of the silicon carbide crystal, and the display module is used to display in real time the mass of the silicon carbide crystal (8) obtained by the calculation module.

2. The measuring system according to claim 1, characterized in that The first conductive rod (1) and the second conductive rod (5) are both made of graphite material.

3. A measurement method of the measurement system according to claim 1 or 2, characterized in that: The following steps are involved: (1) Detect and obtain the total resistance of the system when the crystal is not grown; (2) growing silicon carbide crystals, moving the graphite disk, measuring the real-time resistance between the first conductive rod and the second conductive rod, and collecting displacement data of the graphite disk; (3) Calculate the resistance of the crystal at this time based on the real-time resistance value, the total resistance value of the device, and the displacement data of the graphite disk; (4) Calculating the crystal quality based on the resistivity of the crystal and the obtained crystal resistance; (5) Real-time display of calculated crystal quality.

4. The measuring method according to claim 3, characterized in that: The total resistance R in step (1) 总0 The calculation formula is: R 总0 =R 系统 +R 原料1 +R 籽晶1 Among them, R 系统 is the total resistance of the first conductive rod, the second conductive rod, the graphite disk and the crucible, R 原料1 is the resistance of the liquid raw material in the crucible, R 籽晶1 is the resistance value of the seed crystal placed under the graphite disk.

5. The measuring method according to claim 3, characterized in that: The crystal resistance R in step (3) 晶体 The calculation formula is: R 总 =R 总0 +R 晶体 +ΔR 原料 Among them, R 总 is the real-time resistance between the first conductive rod and the second conductive rod, ΔR 原料 is the change in resistance of the liquid material.

6. The measuring method according to claim 5, characterized in that: The resistance value R 晶体 The calculation formula is: Among them, ρ 晶体 is the resistivity of the crystal, L 晶体 is the elongation length of the crystal, S 晶体 is the cross-sectional area of ​​the crystal; The ΔR 原料 The calculation formula is: Among them, ρ 原料 The resistivity of the liquid material is ΔL 原料 is the variable length of the liquid raw material, S 原料 is the cross-sectional area of ​​the liquid raw material; The graphite disk displacement distance L 石墨盘 The calculation formula is: L 石墨盘 =L 晶体 +ΔL 原料 。 7. The measuring method according to claim 3, characterized in that: The calculation formula of the crystal mass m in step (4) is: m=m 籽晶 +ε·S 晶体 ·L 晶体 Among them, m 籽晶 is the mass of the seed crystal, and ε is the density of the crystal.

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