WO2022143144A1

WO2022143144A1 - Ion source having coil structure capable of changing along with discharge cavity structure

Info

Publication number: WO2022143144A1
Application number: PCT/CN2021/137797
Authority: WO
Inventors: 张瑶瑶; 刘小波; 胡冬冬; 张怀东; 刘海洋; 李娜; 郭颂; 李晓磊; 许开东
Original assignee: 江苏鲁汶仪器有限公司
Priority date: 2021-01-04
Filing date: 2021-12-14
Publication date: 2022-07-07
Also published as: TW202228180A; CN114724912A; KR20230119210A

Abstract

Disclosed is an ion source having a coil structure capable of changing along with a discharge cavity structure, comprising an ion source cavity, a coil support, a coil, and a discharge cavity body which are coaxially arranged in sequence from outside to inside. The discharge cavity body comprises a discharge cavity top part, a discharge cavity middle part, and a discharge cavity bottom part; the discharge cavity top part is a hollow ring; the discharge cavity bottom part is a disc provided with an air inlet in the center; the discharge cavity middle part comprises an upper straight cylinder and a lower dome-shaped cylinder; an outer ring of the coil support is mounted on the inner wall surface of the ion source cavity, and the shape of the inner wall surface of the coil support is the same as the shape of the discharge cavity body; the coil is mounted in the coil support and comprises a cylindrical helical coil and a dome-shaped coil; the position of the cylindrical helical coil corresponds to the position of the upper straight cylinder, and the position of the dome-shaped coil corresponds to the position of the lower dome-shaped cylinder; the distance from each layer of the coil and the outer wall surface of the discharge cavity body is equal. According to the present application, a spiral ICP source is combined with a cylindrical ICP source, such that the plasma density in a discharge cavity body can be adjusted in a segmented manner, and then the etching uniformity is improved.

Description

An ion source whose coil structure can be changed with the discharge chamber structure

Related applications

This application claims the priority of the Chinese patent application filed on January 4, 2021 with the application number 202110002163.3 and the application title "An ion source whose coil structure can change with the discharge chamber structure", the entire contents of which are Incorporated herein by reference.

technical field

The present application relates to the field of ion beam etching, in particular to an ion source whose coil structure can be changed with the discharge cavity structure.

Background technique

An ion source is a device that ionizes neutral atoms or molecules and extracts an ion beam from it. It is various types of ion accelerators, mass spectrometers, electromagnetic isotope separators, ion implanters, ion beam etching devices, and ion thrusters. And an indispensable part of equipment such as neutral beam injectors in controlled fusion devices.

Radio Frequency Inductively Coupled Plasma (RFICP) sources can resonate in the megahertz range and can efficiently generate plasma at low gas pressures and transfer energy to the plasma efficiently. Due to its simple structure, it can generate high-density plasma The advantages of pure plasma, long service life, and good performance-price ratio, so it has developed rapidly in recent years. The currently used RF ICP (Inductively Coupled Plasma) sources are mainly cylindrical, as shown in Figure 1. RF ICP The RF coil of the source is wound around the electrically insulated quartz discharge chamber. When RF power is applied to the coil through the matching network, a radio frequency current flows through the coil, thus generating a radio frequency magnetic flux, which is axially generated inside the discharge chamber. A radio frequency electric field is induced in which the electrons are accelerated by the electric field, resulting in a plasma, and the energy of the coil is coupled into the plasma.

Because the radio frequency ICP source is cylindrical, when the radio frequency power supply is loaded on the radio frequency coil, due to the skin effect of the current, the current mainly flows in the cavity wall of the discharge cavity and gradually decays in the skin layer, so the current in the discharge cavity The plasma density generally shows a trend of high on both sides and low in the middle, as shown by the solid line in Figure 2. Affected by RF power and working pressure, the plasma density distribution in the reaction chamber will also have a saddle-shaped trend (shown by the dotted line in Figure 2). Due to the uneven plasma density distribution, the etching rate is uneven, which affects the etching uniformity. .

SUMMARY OF THE INVENTION

Exemplary embodiments of the present application provide an ion source whose coil structure can be changed with the discharge cavity structure, and the ion source with the coil structure changing with the discharge cavity structure combines a coil-shaped ICP source with a cylindrical ICP source, The plasma density in the discharge chamber body can be adjusted in stages, and the etching uniformity can be improved.

Exemplary embodiments of the present application provide an ion source whose coil structure can be changed with the structure of a discharge cavity, including an ion source cavity, a coil support, a coil and a discharge cavity body that are coaxially arranged in sequence from outside to inside.

The discharge chamber body includes a discharge chamber top, a discharge chamber middle and a discharge chamber bottom which are connected in sequence.

The top of the discharge chamber is a hollow ring and is located on the plasma outlet side.

The bottom of the discharge chamber is a disc with an air inlet hole in the center. Among them, the air inlet hole is used to introduce the gas to be ionized. The center of the hollow ring and the center of the disk are both located on the central axis of the discharge chamber body.

The middle part of the discharge chamber includes an upper end straight tube and a lower end dome tube which are connected in sequence. The top of the upper straight cylinder is connected with the top of the discharge chamber in sequence, and the bottom of the lower Dome-shaped cylinder is connected with the outer edge of the bottom of the discharge chamber in sequence.

The outer ring supported by the coil is installed on the inner wall surface of the ion source cavity, and the shape of the inner wall surface supported by the coil is the same as the shape of the body of the discharge chamber.

The coil is installed in the coil support, and the two ends of the coil are respectively connected with the radio frequency source. Coils include cylindrical helical coils and Dome-type coils. The position of the cylindrical helical coil corresponds to the position of the upper end straight cylinder, and the position of the Dome type coil corresponds to the position of the lower end Dome type cylinder. The distances from each layer of coils to the outer wall of the discharge chamber body are equal.

In one embodiment, the wall thickness of the discharge chamber body ranges from 2 mm to 20 mm.

In one embodiment, the material of the discharge chamber body is quartz or ceramic.

In one embodiment, when the material of the discharge chamber body is quartz, the distance between each layer of coils and the outer wall surface of the discharge chamber body ranges from 2 mm to 30 mm. When the material of the discharge chamber body is ceramic, the distance between each layer of coils and the outer wall surface of the discharge chamber body ranges from 0 mm to 30 mm.

In one embodiment, the wall thickness of the discharge chamber body is H, the distance from each layer of coils to the outer wall of the discharge chamber body is L, and H and L are determined according to the required plasma density in the discharge chamber body.

In one embodiment, the values of H and L are chosen to be small when the desired plasma density within the discharge chamber body is high. Larger values of H and L are chosen when the desired plasma density within the discharge vessel body is low.

In one embodiment, when the wall thickness H of the discharge chamber body is determined, the plasma density in the discharge chamber body is adjusted by adjusting the distance L from each layer of coils to the outer wall surface of the discharge chamber body. When the wall thickness H of the discharge chamber body is relatively large, by reducing L, the plasma density in the discharge chamber body can be made uniform. When the wall thickness H of the discharge chamber body is small, by increasing L, the plasma density in the discharge chamber body can be made uniform.

In one embodiment, a uniform air plate is coaxially installed on the inner wall surface of the bottom of the discharge chamber, and the air uniform plate has a uniform air cavity communicated with the air inlet hole.

In one embodiment, the inner wall surface of the coil support is provided with a notch for installing the coil.

In one embodiment, the coil is formed by 3D printing.

This application has the following beneficial effects:

In the present application, a coil-shaped inductively coupled plasma (Inductive Coupled Plasma, ICP) source is combined with a cylindrical ICP source, which can adjust the plasma density in sections and improve the etching uniformity.

Inside the Dome-type cylinder at the lower end of the discharge chamber body, the plasma ionization is performed by the Dome-type coil; the Dome-type coil can be decomposed into an axial helical coil and a radial coil-shaped plane coil; wherein, the helical coil can make the discharge chamber The radio frequency electric field is induced along the axial direction, while the coil-shaped planar coil induces the radio frequency electric field in the radial direction in the discharge chamber, so that the plasma density distribution in the entire discharge chamber is uniform and the etching uniformity is ensured.

Description of drawings

FIG. 1 shows a schematic diagram of the structure of the coil and the discharge chamber of the ion source in the prior art.

FIG. 2 shows a schematic diagram of the plasma density distribution in the discharge chamber of the ion source in the prior art.

FIG. 3 shows a schematic diagram of an ion source in which the coil structure can be changed with the discharge cavity structure according to an embodiment of the present application.

FIG. 4 shows a schematic structural diagram of a discharge chamber according to an embodiment of the present application.

FIG. 5 shows a schematic structural diagram of a coil support according to an embodiment of the present application.

FIG. 6 shows a schematic structural diagram of a coil according to an embodiment of the present application.

FIG. 7 shows a schematic diagram of manufacturing a coil using a coil tool according to an embodiment of the present application.

Reference number:

1. The body of the discharge chamber; 11. The top of the discharge chamber; 12. The middle of the discharge chamber; 121. The upper end straight cylinder; 122. The lower end Dome-shaped cylinder;

2. Coil;

3. Coil support; 31. Notch;

4. Coil tooling;

51～52. Radio frequency column; 61～62. Conductor; 7. Air distribution plate; 10. Grid assembly.

Detailed ways

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. The drawings in the following description are only some embodiments of the present application, and for those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort. The embodiments described below are some, but not all, embodiments of the present application. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of this application.

It is to be understood that the terms "comprising" and "comprising" used in the description and claims of this application indicate the presence of the described features, integers, steps, operations, elements and/or components, but do not exclude one or more other The presence or addition of features, integers, steps, operations, elements, components and/or sets thereof.

In the description of this application, it should be understood that the orientations or positional relationships indicated by the terms "left", "right", "upper", "lower", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for convenience This application is described and simplified without indicating or implying that the referred device or element must have a particular orientation, be constructed and operate in a particular orientation.

As shown in FIG. 3 , an embodiment of the present application proposes an ion source whose coil structure can be changed with the discharge cavity structure, including an ion source cavity, a coil support 3 , a coil 2 and a discharge cavity that are coaxially arranged from outside to inside. Body 1.

As shown in FIG. 4 , the discharge chamber body 1 includes a discharge chamber top 11 , a discharge chamber middle 12 and a discharge chamber bottom 13 which are connected in sequence. The top 11 of the discharge chamber, the middle part 12 of the discharge chamber and the bottom 13 of the discharge chamber can be formed by fusion welding, and can also be integrally formed.

The top of the discharge chamber is a hollow ring and is located on the plasma outlet side, that is, close to the grid assembly 10 of the ion source. The grid assembly 10 includes a screen grid, an acceleration grid, and the like.

The bottom 13 of the discharge chamber is a disk with an air inlet 131 in the center. Wherein, the center of the hollow ring and the center of the disk are both located on the central axis of the discharge chamber body 1 .

The above-mentioned gas inlet holes are used to introduce gas to be ionized, such as argon (Ar) and the like. The outer circumference of the air inlet hole 131 may also be provided with a gas-distribution plate installation hole 132 for coaxially installing the gas-distribution plate 7 on the inner wall surface of the bottom 13 of the discharge cavity. cavity. The setting of the air distribution plate 7 can make the air intake uniform. The diameter of the bottom 13 of the discharge chamber should be more than 5 mm larger than the outer diameter of the gas-distributing plate 7 , and should not exceed the maximum inner diameter of the body 1 of the discharge chamber.

The middle part of the discharge chamber includes an upper end straight cylinder 121 and a lower end Dome type cylinder 122 which are connected in sequence. The top of the upper straight cylinder 121 is connected to the top of the discharge chamber in sequence, and the bottom of the lower Dome-shaped cylinder 122 is sequentially connected to the outer edge of the bottom 13 of the discharge chamber.

In order to ensure that the discharge chamber body 1 has sufficient strength, the wall thickness of the discharge chamber body 1 should not be too thin. At the same time, in order to ensure the plasma density of the discharge chamber and the influence of material processing, the wall thickness of the discharge chamber body 1 should not be too thick. Therefore, the discharge chamber body 1 should not be too thick. The wall thickness of the main body 1 can be selected from 2 to 20 mm.

The material of the discharge chamber body 1 can be ceramic or quartz.

The outer ring of the coil support 3 is installed on the inner wall surface of the ion source cavity, and the shape of the inner wall surface of the coil support 3 is the same as that of the discharge chamber body 1 . As shown in FIG. 5 , the inner wall surface of the coil support 3 is provided with a notch 31 for installing the coil for installing the coil 2 . The material of the coil support 3 can be insulating materials such as ceramics and polytetrafluoroethylene.

Both ends of the coil 2 are connected to the radio frequency source through the

radio frequency column

51 or 52 and the

wire

61 or 62 respectively.

As shown in FIG. 6, the coil 2 includes a cylindrical helical coil and a Dome type coil. The position of the cylindrical helical coil corresponds to the position of the upper end straight cylinder, and the position of the Dome type coil corresponds to the position of the lower end Dome type cylinder.

The distances from each layer of coils 2 to the outer wall surface of the discharge chamber body 1 are equal. Ensuring the distance between the coil 2 and the discharge chamber body 1 is of great significance to the plasma density distribution in the discharge chamber body 1. The shape of the coil 2 should be consistent with the structure of the discharge chamber body 1. If the material of the discharge chamber body 1 is quartz , the distance from each layer of coil 2 to the outer wall of the discharge chamber body 1 is 2-30 mm. If the material of the discharge chamber body 1 is ceramic, the distance L from each layer of coil 2 to the outer wall of the discharge chamber body is 0-30mm. Due to the high hardness and high temperature resistance of ceramics, when L=0, that is, the coil 2 is fixed on the ceramic discharge chamber body 1 .

In order to ensure that the distance between each coil 2 and the middle 12 of the discharge cavity is consistent, a coil tool 4 is required when winding the coil 2. The structure of the coil 2 tool is shown in Figure 7, which can be integrated or composed of multiple parts. 3D printing can be used during processing.

In addition, the distance from the coil 2 to the bottom 1 of the discharge cavity is adjustable, and the position of the bottom end of the coil 2 may be below or above the bottom 13 of the discharge cavity.

When the flow rate of Ar plasma gas entering the discharge chamber body 1 is determined, the wall thickness of the discharge chamber body is H, and the distance between each layer of coils and the outer wall of the discharge chamber body is L, then H and L are determined according to the inside of the discharge chamber body. The desired plasma density is selected. In one embodiment, the selection method includes:

A. If the plasma density in the discharge chamber body 1 is required to be high, the wall thickness of the discharge chamber body 1 can be selected to be small, and the distance between the discharge chamber body 1 and the coil 2 can be reduced at the same time; L, it can be understood that when the plasma density in the discharge chamber body 1 is higher, the wall thickness of the discharge chamber body 1 can be selected to be smaller, and the distance between the discharge chamber body 1 and the coil 2 can be reduced, that is, the selected H and L is smaller; and

B. If the plasma density in the discharge chamber body 1 is required to be low, the wall thickness of the discharge chamber body 1 can be selected to be large, and the distance between the discharge chamber body 1 and the coil 2 can be increased at the same time; L, it can be understood that the lower the plasma density in the discharge chamber body 1, the thicker the wall thickness of the discharge chamber body 1 can be selected, and at the same time the distance between the discharge chamber body 1 and the coil 2 is increased, that is, the selected H and L is larger.

In addition, if the plasma density in the discharge chamber body 1 is expected to be uniform, the wall thickness of the discharge chamber body 1 should be inversely proportional to the distance from the coil 2 to the outer wall of the central portion 12 of the discharge chamber. Specifically, the adjustment method includes:

A. When the wall thickness H of the discharge chamber body 1 is small, the distance between the coil 2 and the discharge chamber body 1 can be selected to be larger; that is, by increasing L, the plasma density in the discharge chamber body 1 can be made uniform. It can be understood that when the wall thickness of the discharge chamber body 1 is smaller, a larger distance can be selected between the coil 2 and the discharge chamber 1, that is, by increasing L, the plasma density in the discharge chamber body 1 can be uniform; as well as

B. When the wall thickness H of the discharge chamber body 1 is large, the distance between the coil 2 and the middle part 1 of the discharge chamber should be reduced; It is understood that the larger the wall thickness H of the discharge chamber body 1 is, the distance between the coil 2 and the middle part 1 of the discharge chamber should be correspondingly reduced, that is, by reducing L, the plasma density in the discharge chamber body 1 can be uniform.

When etching is required, the Ar plasma gas enters the discharge chamber body 1 , and after the RF power supply is connected to the coil 2 , the ionized gas in the discharge chamber body 1 is ionized. Since the distance between the coil 2 and the middle 12 of the discharge chamber remains the same, therefore:

A. Inside the Dome-type cylinder at the lower end of the discharge chamber body, the plasma ionization is performed by the Dome-type coil; the Dome-type coil can be decomposed into an axial spiral coil and a radial coil-shaped plane coil; among them, the spiral coil can make the discharge The radio frequency electric field is induced in the cavity along the axial direction, and the coil-shaped planar coil induces the radio frequency electric field in the radial direction in the discharge cavity, so that the plasma density distribution in the entire discharge cavity is uniform and the etching uniformity is ensured; and

B. Inside the straight cylinder at the upper end of the discharge chamber body 1, plasma ionization is performed by a cylindrical helical coil; the cylindrical helical coil can induce a radio frequency electric field in the discharge chamber along the axial direction. The coil is spread evenly at the bottom. The length of the coil is related to the inductance. Ensuring that the inductance is sufficient can make the plasma density distribution evenly distributed.

Some embodiments of the present application have been described in detail above. However, the present application is not limited to the specific details of the above-mentioned embodiments. Within the scope of the technical concept of the present application, various equivalent transformations can be performed on the technical solutions of the present application. These equivalent transformations All belong to the protection scope of this application.

Claims

An ion source whose coil structure can be changed with the discharge cavity structure, including:

The ion source cavity, the coil support, the coil and the discharge cavity body are arranged coaxially from outside to inside in sequence;

The discharge chamber body includes a discharge chamber top, a discharge chamber middle and a discharge chamber bottom which are connected in sequence; the discharge chamber top is a hollow ring and is located on the plasma outlet side; the center of the discharge chamber bottom is provided with a disc , the disk is provided with an air inlet hole; wherein, the air inlet hole is used to pass the gas to be ionized; the center of the hollow ring and the center of the disk are both located in the center of the discharge chamber body On the axis; the middle part of the discharge chamber includes an upper end straight cylinder and a lower end Dome-shaped cylinder which are connected in sequence; the top end of the upper end straight cylinder is connected with the top of the discharge chamber, and the bottom of the lower end Dome-shaped cylinder is connected with the outer part of the bottom of the discharge chamber. edge connection;

Wherein, the outer ring supported by the coil is installed on the inner wall of the ion source cavity, and the shape of the inner wall supported by the coil is the same as the shape of the discharge chamber body; the coil is installed in the coil support, Both ends of the coil are respectively connected with a radio frequency source; the coil includes a cylindrical helical coil and a Dome-type coil; wherein, the position of the cylindrical helical coil corresponds to the position of the upper straight cylinder, and the Dome-type coil Corresponding to the position of the Dome-shaped cylinder at the lower end; the distances from the coils of each layer to the outer wall surface of the discharge chamber body are equal.
The ion source of claim 1, wherein the wall thickness of the discharge chamber body is in the range of 2 mm to 20 mm.
The ion source according to claim 1, wherein the material of the discharge chamber body is quartz or ceramic.
The ion source according to claim 1, wherein, when the material of the discharge chamber body is quartz, the distance between each layer of the coil and the outer wall of the discharge chamber body ranges from 2 mm to 30 mm; When the material of the discharge chamber body is ceramic, the distance between each layer of the coil and the outer wall surface of the discharge chamber body ranges from 0 mm to 30 mm.
The ion source according to claim 1, wherein the wall thickness of the discharge chamber body is H, and the distance from each layer of the coil to the outer wall of the discharge chamber body is L, wherein according to the The desired plasma density within the discharge vessel body determines H and L.
6. The ion source of claim 5, wherein the values of H and L are selected to be smaller when the desired plasma density within the discharge chamber body is higher; and when the desired plasma density within the discharge chamber body is higher; Larger values of H and L are chosen when the desired plasma density is low.
The ion source according to claim 5, wherein, when the wall thickness H of the discharge chamber body is determined, the distance from each layer of the coil to the outer wall of the discharge chamber body is adjusted by adjusting the distance L, to adjust the plasma density in the discharge chamber body; when the wall thickness H of the discharge chamber body is relatively large, by reducing the distance L, the The plasma density is uniform; when the wall thickness H of the discharge chamber body is small, the distance L is increased to make the plasma density in the discharge chamber body uniform.
The ion source according to claim 1, wherein a uniform air plate is coaxially installed on the inner wall surface of the bottom of the discharge chamber, and the air uniform plate has a uniform air cavity communicated with the air inlet hole.
The ion source according to claim 1, wherein a notch for installing the coil is provided on the inner wall surface of the coil support.
The ion source of claim 1, wherein the coil is 3D printed.