Radio frequency inductively coupled plasma uniformity regulation and control device

Abstract

The invention discloses a radio frequency inductive coupling plasma uniformity regulation and control device, and relates to the technical field of radio frequency plasmas, and the device comprises a discharge chamber, a quartz dielectric window, a radio frequency coil pair and a double-cavity shielding cover. The quartz dielectric window is arranged on the upper surface of the discharge chamber; the radio frequency coil pair is arranged on the upper surface of the quartz dielectric window; the double-cavity shielding cover is arranged on the upper surface of the quartz dielectric window, and two cavities are formed by the double-cavity shielding cover and the upper surface of the quartz dielectric window; the radio frequency coil pair is arranged on the upper surface of the quartz dielectric window, and two radio frequency coils in the radio frequency coil pair are respectively arranged in different cavities; according to the invention, the double-cavity shielding cover is arranged to shield the two radio frequency coils in the radio frequency coil pair, and the position relation of the two radio frequency coils in the radio frequency coil pair is adjusted at the same time, so that the uniformity of the radio frequency inductive coupling plasma can be regulated and controlled.

Description

Technical Field

[0001] The present application relates to the field of radio frequency plasma technology, and in particular to a radio frequency inductively coupled plasma uniformity control device. Background Art

[0002] Low-pressure radio frequency inductively coupled plasma source (RF-ICP) has been widely used in etching, thin film deposition, and material surface treatment due to its advantages such as high plasma density and large-area uniform plasma. The process quality is usually evaluated by some key indicators: the etching process is mainly evaluated by parameters such as etching selectivity, uniformity, anisotropy, low ion energy damage, and etching rate; the deposition process is usually evaluated by parameters such as deposition uniformity and deposition rate. The characteristics of the plasma (such as uniformity, independent control of ion flux and ion energy, plasma density, flux ratio of ions to neutral particles, etc.) directly determine the process results of etching and deposition. Therefore, regulating plasma parameters has become the key to achieving high-quality processing technology, and regulating plasma parameters requires a deep understanding of the generation and transport mechanism of plasma.

[0003] Low-pressure RF inductively coupled plasma source is an important device for preparing flat panel displays. With the development of technology, the size of flat panel displays is getting larger and larger. It has now developed to the 8.5th generation, and the area of ​​flat panel displays has reached 2200×2500mm. 2 In such a large rectangular chamber, when the size of the discharge chamber is comparable to the wavelength of the electromagnetic wave in the plasma (when the electromagnetic wave propagates in the plasma, its wavelength is about 3-5 times smaller than that in the vacuum), the electromagnetic wave will form a standing wave in the discharge chamber, which will seriously damage the uniformity of the plasma. This will directly affect the uniformity and efficiency of the processing technology, resulting in inconsistent product performance or even defects. Summary of the invention

[0004] The purpose of the present application is to provide a radio frequency inductively coupled plasma uniformity control device, which can control the uniformity of radio frequency inductively coupled plasma.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] The present application provides a radio frequency inductively coupled plasma uniformity control device, comprising: a discharge chamber, a quartz dielectric window, a radio frequency coil pair and a double-cavity shielding cover;

[0007] The quartz dielectric window is arranged on the upper surface of the discharge chamber;

[0008] The dual-cavity shielding cover is arranged on the upper surface of the quartz dielectric window, and forms two cavities with the upper surface of the quartz dielectric window;

[0009] The radio frequency coil pair is arranged on the upper surface of the quartz dielectric window, and two radio frequency coils in the radio frequency coil pair are respectively arranged in different cavities.

[0010] Optionally, both radio frequency coils in the radio frequency coil pair are square spiral structures.

[0011] Optionally, the two radio frequency coils in the radio frequency coil pair have the same number of spiral turns.

[0012] Optionally, the number of spiral turns is 4.

[0013] Optionally, the positional relationship between the two radio frequency coils in the radio frequency coil pair is rotational.

[0014] Optionally, the positional relationship between the two radio frequency coils in the radio frequency coil pair is translation.

[0015] Optionally, the positional relationship between the two radio frequency coils in the radio frequency coil pair is a mirror image.

[0016] Optionally, the first distance, the second distance and the third distance of the radio frequency inductively coupled plasma uniformity control device are all equal;

[0017] The first distance is the distance between adjacent turns in the same radio frequency coil;

[0018] The second distance is the distance from the outermost circle of the radio frequency coil to the edge of the upper surface of the quartz dielectric window;

[0019] The third distance is the distance between the outermost circles of the two radio frequency coils in the radio frequency coil pair.

[0020] Optionally, the first distance is 4 cm.

[0021] Optionally, the discharge chamber is a vacuum chamber.

[0022] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0023] The present application provides a radio frequency inductively coupled plasma uniformity control device, comprising a discharge chamber, a quartz dielectric window, a radio frequency coil and a double-cavity shielding cover; a changing magnetic field is induced by an alternating radio frequency current in the radio frequency coil, and the changing magnetic field induces an electric field; the initial seed electrons obtain sufficiently high energy under the acceleration of the induced electric field, bombarding the background gas, thereby causing avalanche ionization of the background gas molecules or atoms, and then generating plasma in the discharge chamber; by changing the geometric shape of the radio frequency coil and the number of coil turns, the coil spacing, etc., the spatial distribution of the electromagnetic field can be affected, thereby significantly improving the uniformity of the plasma; by adding a shielding device between the radio frequency coils, the mutual inductance between the two coils can be weakened, thereby improving the uniformity of the plasma. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 This is a schematic structural diagram of a radio frequency inductively coupled plasma uniformity control device in one embodiment of the present application;

[0026] Figure 2 It is a schematic diagram of a radio frequency coil in a rotational position relationship in one embodiment of the present application;

[0027] Figure 3 It is a schematic diagram of a radio frequency coil in a translational position relationship in one embodiment of the present application;

[0028] Figure 4 This is a schematic diagram of a radio frequency coil in a mirror image position relationship in one embodiment of the present application;

[0029] Figure 5 A distribution diagram of the electron density on the xy plane of a rotating coil structure with electromagnetic shielding in one embodiment of the present application;

[0030] Figure 6 A distribution diagram of the electron density in the xy plane of the electromagnetic shielding translation coil structure in one embodiment of the present application;

[0031] Figure 7 A distribution diagram of the electron density in the xy plane with an electromagnetic shielding mirror coil structure in one embodiment of the present application;

[0032] Figure 8 The distribution diagram of the electron temperature on the xy plane of the electromagnetic shielding rotating coil structure in one embodiment of the present application;

[0033] Fig. 9 A distribution diagram of the electron temperature on the xy plane of an electromagnetic shielding translation coil structure in an embodiment of the present application;

[0034] Fig.10 A distribution diagram of the electron temperature on the xy plane with an electromagnetic shielding mirror coil structure in one embodiment of the present application;

[0035] Fig.11 A distribution diagram of the ionization rate of the electromagnetic shielding rotating coil structure in an embodiment of the present application on the xy plane;

[0036] Fig.12 A distribution diagram of the ionization rate of the electromagnetic shielding translation coil structure in an embodiment of the present application on the xy plane;

[0037] Fig.13 A distribution diagram of the ionization rate of the electromagnetic shielding mirror coil structure in an embodiment of the present application on the xy plane;

[0038] Fig.14 A distribution diagram of the electron flux of the electromagnetic shielding rotating coil structure in the xy plane in one embodiment of the present application;

[0039] Fig.15 A distribution diagram of the electron flux of the electromagnetic shielding translation coil structure in the xy plane in one embodiment of the present application;

[0040] Fig.16 A distribution diagram of the electron flux of the electromagnetic shielding mirror coil structure in the xy plane in one embodiment of the present application;

[0041] Fig.17 A distribution diagram of the electric field of the electromagnetic shielding rotating coil structure in an embodiment of the present application on the xy plane;

[0042] Fig.18 A distribution diagram of the electric field of the electromagnetic shielding translation coil structure in an embodiment of the present application on the xy plane;

[0043] Fig.19 A distribution diagram of the electric field of the electromagnetic shielding mirror coil structure in an embodiment of the present application on the xy plane;

[0044] Fig. 20 In one embodiment of the present application, a distribution diagram of normalized electron density along the x direction of different coil structures of the double coil with or without shielding is obtained by calculating the three-dimensional fluid model.

[0045] Figure numerals: discharge chamber-1; quartz dielectric window-2; radio frequency coil pair-3; double-cavity shielding cover 4. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0047] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0048] In an exemplary embodiment, Figure 1 As shown, a radio frequency inductively coupled plasma uniformity control device is provided, comprising: a discharge chamber 1, a quartz dielectric window 2, a radio frequency coil pair 3 and a dual-cavity shielding cover 4; the quartz dielectric window 2 is arranged on the upper surface of the discharge chamber 1; the discharge chamber 1 is a vacuum chamber. The vacuum chamber system provides a low-pressure environment for the application of the invention. After the discharge gas is introduced into the vacuum chamber, power is applied to the coil, and plasma will be generated in the vacuum chamber. In practical applications, the discharge chamber 1 can be a plasma chamber of any size according to needs to meet different application needs. The radio frequency coil pair 3 is arranged on the upper surface of the quartz dielectric window 2; the dual-cavity shielding cover 4 is arranged on the upper surface of the quartz dielectric window 2, and forms two cavities with the upper surface of the quartz dielectric window 2; the radio frequency coil pair 3 is arranged on the upper surface of the quartz dielectric window 2, and the two radio frequency coils in the radio frequency coil pair 3 are respectively arranged in different cavities. The two radio frequency coils in the radio frequency coil pair 3 have the same number of spiral turns. The number of spiral turns is 4. The positional relationship between the two radio frequency coils in the radio frequency coil pair 3 can be rotation (such as Figure 2 ), translation (such as Figure 3 ) or mirror image (such as Figure 4). Changing the arrangement of the rectangular coils and the distance between the two coils can change the distribution of the electromagnetic field, thereby improving the uniformity of the plasma; by applying a shield between the two coils and reducing the mutual inductance between the two coils, the uniformity of the plasma can be improved; the vacuum chamber is 100 cm long, 50 cm wide, and 20 cm high; the cross-sectional radius of the coil is 0.5 cm; the first distance, the second distance, and the third distance of the RF inductively coupled plasma uniformity control device are all equal; the first distance is the distance between adjacent turns in the same RF coil; the second distance is the distance from the outermost circle of the RF coil to the upper surface edge of the quartz dielectric window 2; the third distance is the distance between the outermost circles of the two RF coils in the RF coil pair 3. The first distance is 4 cm. The present application builds a set of RF discharge chambers in a rectangular process chamber. By changing the coil structure and adding shielding to the double coils, the uniformity of high-density plasma generated in large-area discharge can be effectively improved, which is of great significance for the design of large-area ICP sources and the optimization of flat panel display processes. Both RF coils in the RF coil pair 3 are square spiral structures. In addition, the radio frequency coil includes any radio frequency coil structure (rectangular, circular, elliptical, conical, etc.), and in practical applications, a radio frequency coil of any structure can be used according to requirements.

[0049] RF inductively coupled plasma uniformity control device such as Figure 1 The discharge chamber 1 structure of the large-area rectangular RF ICP source includes a (plasma) discharge chamber 1, a quartz dielectric window 2, a RF coil and a dual-cavity shielding cover 4. The length of the discharge chamber 1 is 100 cm, the width is 50 cm, and the height is 20 m. The thickness of the quartz dielectric window 2 is 2 cm, and the RF dual coil is placed above the quartz dielectric window 2. There is a dual-cavity shielding cover 4 around the RF coil, and its height is 10 cm. The alternating RF current in the RF coil induces a changing magnetic field, and the changing magnetic field induces an electric field. The initial seed electrons are accelerated by the induced electric field and obtain sufficiently high energy to bombard the background gas, thereby causing avalanche ionization of the background gas molecules or atoms, and then generating plasma in the discharge chamber 1.

[0050] Figure 2-Figure 4 This is a schematic diagram of a double-coil structure, where each coil has 4 turns, the distance between two turns of the coil is 4 cm, and the distance between the outermost coil and the chamber wall is also 4 cm. Figure 2 It is a rotated coil structure. The coil on the right is obtained by rotating the coil on the left 180 degrees around the z-axis. Figure 3 It is a translation coil structure. The coil on the right can be obtained by translating the coil on the left by 48 cm in the positive direction of the x-axis. The sizes of the two coils are exactly the same. Figure 4 It is a mirror coil structure, and the left and right coils are mirror-symmetrical about the center of the chamber.

[0051] For this application, a three-dimensional fluid model was used for simulation verification. It consists of three parts: plasma module, electromagnetic field module and electrostatic field module. Under appropriate boundary conditions, the spatial distribution of plasma parameters can be obtained through the mutual coupling of these three modules.

[0052] The distribution of electron density, electron temperature, ionization rate, electron flux and deposition power density of the three coils under shielding conditions is shown in Figure 2. Figure 5-Figure 19 . For the rotating coil structure, the coil shielding has no effect on the spatial distribution of the electron density. For the translational coil structure, adding a shield between the double coils can eliminate the phenomenon of the left-right asymmetry of the electron density about the symmetry axis. This is because the two coils do not affect each other after the shielding is added. Since the sizes of the two coils are exactly the same, the electric fields generated are the same, so that the ionization rate is symmetrical about the symmetry axis at x = 0 cm, and the electron flux is almost unchanged after the shielding is added. Therefore, adding a shield to the translational coil structure can eliminate the phenomenon of asymmetric electron density. For the mirror coil structure, the electron density at the center of the XY plane decreases after the shielding is added. Because the mirror coil structure weakens the mutual inductance between the two coils after the shielding is added, the electric field near x = 0 cm is weakened, the ionization rate is reduced, and the electron density at the center of the XY plane is reduced. After the shielding is added, the electron flux of the rotating and translational coil structure is almost unchanged, but the electron flux of the mirror coil structure near x = 0 cm is reduced. Therefore, for the rotating and translational coil structure, the coil shielding has no effect on the electron temperature distribution. For the mirror coil structure, the electron temperature near x = 0 cm is reduced after the shielding is added.

[0053] Fig. 20 This is an application verification example of the method of adjusting the dual coil structure to improve plasma uniformity. It shows the distribution of normalized electron density along the x direction of different coil structures in the case of dual coils without shielding and with shielding. For the rotating and translating coil structure, the electron density shows a saddle-shaped distribution regardless of whether there is a shield between the two coils. However, when shielding is added to the mirror coil structure, the electron density in the center of the chamber decreases, producing a more uniform plasma. This is because the addition of shielding to the mirror coil structure weakens the mutual inductance between the two coils, resulting in a weakening of the electric field near x = 0 cm and a decrease in the ionization rate, so the electron density in the center of the chamber decreases and the uniformity improves. For the rotating and translating coil structure, coil shielding has no effect on the electron temperature distribution. For the mirror coil structure, after adding shielding, the electron temperature near x = 0 cm decreases, and the electron temperature changes from a single-peak distribution to a quasi-bimodal distribution. From the distribution of normalized electron density along the x direction, it can be found that the shielded mirror coil structure produces the best plasma uniformity. The results show that the shielded mirror coil structure can improve the uniformity of plasma.

[0054] Among the rotating coil, translation coil and mirror coil structures, the rotating coil structure produces the best plasma uniformity. When shielding is added to the mirror coil structure, the electron density in the center of the chamber is reduced, producing a more uniform plasma. In summary, by changing the coil structure and adding shielding to the double coils, high-density and uniform plasma can be produced in large-area discharges, which is of great significance for the design of large-area ICP sources and the optimization of flat panel display processes.

[0055] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A radio frequency inductively coupled plasma uniformity control device, characterized in that: include: A discharge chamber, a quartz dielectric window, a radio frequency coil pair, and a dual-cavity shield; The quartz dielectric window is arranged on the upper surface of the discharge chamber; The dual-cavity shielding cover is arranged on the upper surface of the quartz dielectric window, and forms two cavities with the upper surface of the quartz dielectric window; The radio frequency coil pair is arranged on the upper surface of the quartz dielectric window, and two radio frequency coils in the radio frequency coil pair are respectively arranged in different cavities.

2. The radio frequency inductively coupled plasma uniformity control device according to claim 1, characterized in that: The two radio frequency coils in the radio frequency coil pair are both square spiral structures.

3. The radio frequency inductively coupled plasma uniformity control device according to claim 2, characterized in that: The two radio frequency coils in the radio frequency coil pair have the same number of spiral turns.

4. The radio frequency inductively coupled plasma uniformity control device according to claim 3, characterized in that: The number of spiral turns is 4.

5. The radio frequency inductively coupled plasma uniformity control device according to claim 1, characterized in that: The positional relationship between the two radio frequency coils in the radio frequency coil pair is rotational.

6. The radio frequency inductively coupled plasma uniformity control device according to claim 1, characterized in that: The positional relationship between the two radio frequency coils in the radio frequency coil pair is translation.

7. The radio frequency inductively coupled plasma uniformity control device according to claim 1, characterized in that: The positional relationship between the two radio frequency coils in the radio frequency coil pair is a mirror image.

8. The radio frequency inductively coupled plasma uniformity control device according to claim 1, characterized in that: The first distance, the second distance and the third distance of the radio frequency inductively coupled plasma uniformity control device are all equal; The first distance is the distance between adjacent turns in the same radio frequency coil; The second distance is the distance from the outermost circle of the radio frequency coil to the edge of the upper surface of the quartz dielectric window; The third distance is the distance between the outermost circles of the two radio frequency coils in the radio frequency coil pair.

9. The radio frequency inductively coupled plasma uniformity control device according to claim 8, characterized in that: The first distance is 4 cm.

10. The radio frequency inductively coupled plasma uniformity control device according to claim 9, characterized in that: The discharge chamber is a vacuum chamber.

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