A hollow probe for plasma diagnostics

Abstract

A hollow probe for plasma diagnosis, belonging to the field of plasma scientific parameter measurement technology, includes a hollow shell, an insulating sleeve and a metal wire, one end of the hollow shell is a closed end, and the other end is an open end, the insulating sleeve enters the hollow shell through the open end and is fixedly connected to the hollow shell, the hollow shell is located on the outside of the insulating sleeve, there is a gap between the insulating sleeve and the hollow shell, the metal wire is installed in the insulating sleeve, one end of the metal wire is connected to the hollow shell, and the other end extends to the outside of the insulating sleeve. It can be used for plasma diagnosis in a conductive film deposition environment to avoid the probe being scrapped due to a short circuit with the conductive coating on the insulating bracket, and can more accurately measure the density of the plasma.

Description

Technical Field

[0001] The invention belongs to the technical field of plasma scientific parameter measurement, and in particular relates to a hollow probe for plasma diagnosis. Background Art

[0002] The probe is a commonly used device for diagnosing plasma parameters, and can be divided into single-probe, double-probe, and triple-probe diagnostic methods. The single-probe method is a small metal electrode placed in the plasma. A scanning bias voltage is applied between the probe and the plasma ground, and then the probe current is measured as the scanning bias voltage changes to obtain a volt-ampere characteristic curve. The plasma parameters can be obtained by analyzing the volt-ampere characteristic curve. The double-probe method uses two small metal electrodes close to each other. A scanning bias voltage is applied between the two electrodes, and the plasma parameters are also obtained by analyzing the volt-ampere characteristic curve. The triple-probe method uses three small metal electrodes close to each other. A fixed voltage is applied between two of the electrodes, and the voltage and current between the two electrodes and the third electrode are measured. The plasma density and electron temperature can be calculated using the formula.

[0003] The shapes of the probes used in the prior art are usually cylindrical, spherical or planar. Cylindrical probes are the most widely used because they are easy to make and have less disturbance to the plasma, but the cylindrical probes have poor spatial symmetry, the electric field at the tip is strong, and the collected current density on the probe is uneven, thereby generating a surface potential difference and current, which affects the accuracy of the measurement. In addition, the part of the cylindrical probe close to its insulating support will be blocked by the sheath of the insulating support and cannot effectively collect charges, so the effective charge collection area cannot be accurately determined, resulting in inaccurate calculation of the electron density. Compared with the cylindrical probe, the spherical probe has less disturbance to the plasma and good spatial symmetry, but the spherical probe cannot avoid the problem that the part close to the insulating support is blocked by the sheath of the insulating support and cannot effectively collect charges, so the effective charge collection area cannot be accurately determined and the electron density calculation is inaccurate. Planar probes are the least used because of their large disturbance to the plasma and imperfect theory, and the planar probe also has the problem of uneven electric field and the probe being blocked by the sheath of the insulating support.

[0004] More importantly, probes of these shapes cannot be used for plasma diagnosis in conductive film deposition environments, because in such environments, the probes of these shapes and their insulating support surfaces will be quickly coated with a layer of conductive film and short-circuit, making the probes unusable. Since there are a large number of plasmas in conductive film deposition environments that need to be diagnosed in actual production applications, such as plasmas in TiN, CrN, ITO and other thin film deposition environments, it is very necessary to solve this problem. Summary of the invention

[0005] The purpose of the present invention is to provide a hollow probe for plasma diagnosis to solve the problem that the prior art probe cannot be used for plasma diagnosis in a conductive film deposition environment and is inaccurate in measuring other plasma diagnosis.

[0006] The present invention is a hollow probe for plasma diagnosis realized in the following manner, comprising a hollow shell, an insulating sleeve and a metal wire. The hollow shell has a closed end at one end and an open end at the other end, and the interior thereof is a cavity. After the insulating sleeve enters the interior of the hollow shell through the open end, the insulating sleeve can be fixedly connected to the inner wall of the closed end of the hollow shell by gluing, or can be fixedly connected to the inner wall of the closed end of the hollow shell by tightening with screws, so that the hollow shell is sleeved on the outer wall of the insulating sleeve, so that the hollow shell is located outside the insulating sleeve. A gap is left between the insulating sleeve and the hollow shell, and the metal wire is installed in the insulating sleeve, that is, the insulating sleeve wraps the metal wire, and one end of the metal wire is connected to the hollow shell. There are two ways of connection, one is that the metal wire is directly in contact with the hollow shell for connection, and the other is that the metal wire is indirectly in contact with the hollow shell through a conductive medium for connection, and the other end extends to the outside of the insulating sleeve and is connected to an external device.

[0007] The hollow shell is made of metal material.

[0008] The preferred hollow shell is a hemispherical shell or a spherical cylindrical shell.

[0009] At least two grooves are arranged at one end of the insulating sleeve fixed to the hollow shell.

[0010] The outer diameter of the hollow shell is 1mm-100mm, and the wall thickness of the hollow shell is 0.1mm-1mm.

[0011] The width of the gap is less than one fifth of the outer diameter of the hollow shell, and the depth of the gap is greater than 3 times the maximum width of the gap.

[0012] Preferred metal materials are tungsten, molybdenum, tantalum, nickel, platinum, brass or stainless steel.

[0013] The beneficial effects of the present invention are as follows: when used in a conductive thin film deposition environment, it can avoid the probe and the conductive coating on the insulating support from being short-circuited and thus being scrapped, and thus can be used for plasma diagnosis in a conductive thin film deposition environment; on the other hand, it avoids shielding of the probe by the sheath of the insulating support, and can more accurately measure the density of the plasma. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The figure is a structural diagram of a hollow probe whose hollow shell is a hemispherical shell;

[0015] Figure 2 A structural diagram of a hollow probe in which a hollow shell and an insulating sleeve are connected by screws;

[0016] Figure 3 The structure diagram of the hollow probe whose hollow shell is a spherical cylindrical shell;

[0017] Figure 4 The structure diagram of the hollow probe using an insulating sleeve with grooves;

[0018] like Figures 1 to 4 The hollow shell (1), the insulating sleeve (2), the metal wire (3), the closed end (4), the open end (5), the gap (6), the screw (7), and the groove (8). DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0020] See also Figure 1-Figure 4 A hollow probe for plasma diagnosis includes a hollow shell 1, an insulating sleeve 2 and a metal wire 3. The hollow shell 1 has a closed end 4 at one end and an open end 5 at the other end, and the interior thereof is a cavity. The hollow shell 1 is made of metal materials such as tungsten, molybdenum, tantalum, nickel, platinum, brass, or stainless steel. The size of the hollow shell 1 is related to the density of the plasma to be measured. The outer diameter generally ranges from 1mm to 100mm. In order to ensure the strength of the hollow shell 1, the wall thickness ranges from 0.1mm to 1mm. After the insulating sleeve 2 enters the interior of the hollow shell 1 through the open end 5, the insulating sleeve 2 can be fixedly connected to the inner wall of the closed end 4 of the hollow shell 1 by gluing, or can be tightened with the hollow shell by screws 7. 1 is fixedly connected to the inner wall of the closed end 4 of the hollow shell 1, so that the hollow shell 1 is sleeved on the outer wall of the insulating sleeve 2, so that the hollow shell 1 is located on the outside of the insulating sleeve 2, and a gap 6 is left between the insulating sleeve 2 and the hollow shell 1, the width of the gap 6 is less than one-fifth of the outer diameter of the hollow shell 1, and the depth of the gap 6 is greater than 3 times its maximum width; the metal wire 3 is installed in the insulating sleeve 2, one end of the metal wire 3 is connected to the hollow shell 1, that is, the metal wire 3 is directly connected to the connection of the hollow shell 1, or the metal wire 3 is indirectly connected to the hollow shell 1 through a conductive medium, and the other end extends to the outside of the insulating sleeve 2 and is connected to an external device.

[0021] The preferred hollow shell 1 is a hemispherical shell or a spherical cylindrical shell.

[0022] At least two grooves are arranged at one end of the insulating sleeve fixed to the hollow shell.

[0023] Embodiment 1, as Figure 1 The hollow probe used in plasma diagnostics for measuring conductive film deposition environments is shown in the plasma density range of 10 8 -10 10 / cm 3 The hollow shell 1 is a hemispherical shell made of 304 stainless steel with an outer diameter of 1.2 mm and a wall thickness of 0.1 mm. The outer diameter of the insulating sleeve 2 is 0.6 mm. The gap 6 between the insulating sleeve 2 and the hollow shell 1 is less than 0.24 mm, and the depth of the gap 6 is greater than 3 times its maximum width. The insulating sleeve 2 is bonded and fixed to the hollow shell 1 with silver glue. The metal wire 3 is bonded and directly connected to the hollow shell 1 with silver glue, and is led out through the insulating sleeve 2.

[0024] Embodiment 2, as Figure 2 The hollow probe used in the diagnosis of low-density space plasmas is shown in the figure. The plasma density range is 10 5 -10 6 / cm 3 The hollow shell 1 is a hemispherical shell made of brass with an outer diameter of 50 mm and a wall thickness of 1 mm. The outer diameter of the insulating sleeve 2 is 30 mm. The gap 6 between the insulating sleeve 2 and the hollow shell 1 is less than 10 mm, and the depth of the gap 6 is greater than 3 times its maximum width. The screw 7 is fixed on the inner wall of the closed end 4 of the hollow shell 1, and the insulating sleeve 2 is installed on the screw 7 through a threaded connection. The metal wire 3 is fixed on the screw 7 by welding to form an indirect conduction with the hollow shell 1, and is led out through the insulating sleeve 2.

[0025] Compared with Example 1, in Example 2, the insulating sleeve 2 is not in direct contact with the hollow shell 1, forming a curved gap 6, which can more effectively avoid a short circuit between the hollow shell 1 and the conductive coating on the insulating sleeve 2.

[0026] Embodiment 3, as Figure 3 The hollow probe used in plasma diagnostics for measuring conductive film deposition environments is shown in the plasma density range of 10 8 -10 10 / cm 3 The hollow shell 1 is a spherical cylindrical shell made of 304 stainless steel. The outer diameters of the spherical top and the cylinder are both 1.2 mm, and the wall thickness is 0.1 mm. The outer diameter of the insulating sleeve 2 is 0.6 mm. The gap 6 between the insulating sleeve 2 and the hollow shell 1 is less than 0.24 mm, and the depth of the gap 6 is greater than 3 times its maximum width. The insulating sleeve 2 is bonded and fixed to the hollow shell 1 with silver glue. The metal wire 3 is bonded and directly connected to the hollow shell 1 with silver glue, and is led out through the insulating sleeve 2.

[0027] Compared with Example 1, Example 3 has a deeper gap between the insulating sleeve 2 and the hollow shell 1, and the conductive coating component is less likely to be deposited into the gap, which can more effectively avoid the short circuit between the hollow shell 1 and the conductive coating on the insulating sleeve 2. However, compared with the hollow shell 1 of the hemispherical shell, the hollow shell 1 of the spherical cylindrical shell of the same diameter has a larger surface area, a larger collection current, a larger disturbance to the plasma, and a larger power consumption of the probe. Therefore, it is necessary to select a suitable hollow shell 1 according to the actual plasma situation during use, so as to overcome the problem of short circuit of the conductive coating, reduce the collection current and plasma disturbance, and obtain accurate measurement results.

[0028] Embodiment 4, as Figure 4 A hollow probe used in plasma diagnosis for measuring the deposition environment of a conductive film, wherein the hollow shell 1 is a spherical cylindrical shell made of 304 stainless steel, at least two annular grooves 8 are formed on one end of the insulating sleeve 2, the insulating sleeve 2 is bonded and fixed to the hollow shell 1 with silver glue, the metal wire 3 is bonded and directly connected to the hollow shell 1 with silver glue, and is led out through the insulating sleeve 2.

[0029] Compared with Example 3, in Example 4, an annular groove 8 is provided on the insulating sleeve 2, and the conductive coating component is not easy to form a continuous conductive film layer, which can more effectively avoid the short circuit between the hollow shell 1 and the conductive coating on the insulating sleeve 2. On the other hand, the enhanced short circuit prevention effect relaxes the depth requirement of the gap 6, and can reduce the surface area of ​​the hollow shell 1, thereby reducing the collection current and the disturbance to the plasma and the power consumption of the probe.

[0030] In Examples 1-4, the hollow shell 1 is located outside the insulating sleeve 2, which prevents the hollow shell 1 from being shielded by the sheath of the insulating sleeve 2, and the charge collection area is exactly the outer surface area of ​​the hollow shell 1, so that the plasma density can be accurately measured; in contrast, the metal probes in the prior art are located inside the insulating sleeve, and are inevitably partially shielded by the sheath of the insulating sleeve, so that the effective charge collection area of ​​the probe cannot be accurately determined, and thus the plasma density cannot be accurately measured. In addition, in Examples 1-4, the gap between the insulating sleeve and the hollow shell does not directly face the coating source and the plasma, which can more effectively prevent the deposition of coating materials in the gap 6 on the one hand; on the other hand, it is not easy for the plasma to enter the gap 6 and be additionally collected, so the measurement is more accurate.

Claims

1. A hollow probe for plasma diagnosis, characterized in that: The invention comprises a hollow shell (1), an insulating sleeve (2) and a metal wire (3); one end of the hollow shell (1) is a closed end (4) and the other end is an open end (5); the hollow shell (1) is located outside the insulating sleeve (2); the insulating sleeve (2) enters the interior of the hollow shell (1) through the open end (5) and is fixedly connected to the inner wall of the hollow shell (1) by gluing or screws (7); a gap (6) is provided between the insulating sleeve (2) and the hollow shell (1); the metal wire (3) is installed in the insulating sleeve (2); one end of the metal wire (3) is in conduction with the hollow shell (1) and the other end extends to the outside of the insulating sleeve (2); the width of the gap (6) is less than one fifth of the outer diameter of the hollow shell (1), and the depth of the gap (6) is greater than three times the maximum width of the gap (6); and at least two grooves (8) are provided at the end of the insulating sleeve (2) fixed to the hollow shell (1).

2. A hollow probe for plasma diagnosis according to claim 1, characterized in that: The hollow shell (1) is made of metal material.

3. A hollow probe for plasma diagnosis according to claim 1 or 2, characterized in that: The hollow shell (1) is a hemispherical shell or a spherical cylindrical shell.

4. A hollow probe for plasma diagnosis according to claim 3, characterized in that: The outer diameter of the hollow shell (1) is 1 mm-100 mm, and the wall thickness of the hollow shell (1) is 0.1 mm-1 mm.

5. A hollow probe for plasma diagnosis according to claim 2, characterized in that: The metal material is tungsten, molybdenum, tantalum, nickel, platinum, brass or stainless steel.

6. A hollow probe for plasma diagnosis according to claim 1, characterized in that: The screw (7) is fixed on the inner wall of the closed end (4).

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