WO2008031321A1

WO2008031321A1 - Inductive coupling coil and inductive coupling plasma apparatus thereof

Info

Publication number: WO2008031321A1
Application number: PCT/CN2007/002451
Authority: WO
Inventors: Qiaoli Song; Jianhui Nan
Original assignee: Beijing Nmc Co., Ltd.
Priority date: 2006-08-23
Filing date: 2007-08-14
Publication date: 2008-03-20
Also published as: KR101068746B1; KR20090033877A; CN101131893A; SG173346A1; WO2008031320A1; CN101131893B

Abstract

An inductive coupling coil comprises a plenty of separate portions with the same structure. A plenty of separate portions are coaxial and are distributed symmetrically about an axes. An inductive coupling plasma apparatus which applies an inductive coupling coil comprises a reactive chamber, an dielectric window set on the reactive chamber, in which the inductive coupling coil is set on the dielectric window and is connected to an RF source via an RF adapter.

Description

Inductive coupling line 感应 and inductive coupling device using the same

The present invention relates to an accessory for a semiconductor wafer processing apparatus, and more particularly to an inductive coupling coil and an inductive coupling device using the inductive coupling coil. Background technique

At present, with the rapid development of electronic technology, people's integration requirements for integrated circuits are getting higher and higher, which requires enterprises that produce integrated circuits to continuously improve the processing capability of semiconductor wafers. Plasma devices are widely used in the fabrication of devices for IC (Integrated Circuit) or MEMS (Micro Electro Mechanical Systems) devices. Among them, ICP (Inductively Coupled Plasma Device) is widely used in etching and other processes. At low pressure, the reaction gas is excited by RF power to generate ionization to form a plasma. The plasma contains a large amount of active particles such as electrons, ions, excited atoms, molecules and radicals. These active particles and etched substances Various physical and chemical reactions occur on the surface and form volatile products, which can change the surface properties of the material.

The inductively coupled plasma device shown in Figure 1 is the structure employed in most current semiconductor etching equipment. During the semiconductor processing, the process gas entering the reaction chamber 3 from the air inlet 2 in the center of the dielectric window 1 is ionized by the upper inductive coupling coil 4 to form a plasma, and the generated plasma etches the material of the surface of the wafer 5. In the system, the molecular pump withdraws the gas from the reaction chamber 3 and discharges the gas from the reaction chamber 3. In this process, the RF power that causes the gas to ionize to form a plasma comes from the inductive coupling line 圏4. The current excitation method applied to the inductive coupling coil 4 is to add a 13.56 MHz radio frequency, so that the inductive coupling line 圏4 has an RF current and thus a varying magnetic field. According to Faraday's law of electromagnetic induction, the varying magnetic field induces an electric field, thereby ionizing the reaction gas into a plasma in the reaction chamber 3. The excited plasma interacts with the workpiece within the chamber 3, etching the workpiece or depositing material on the workpiece. The workpiece is generally a semiconductor with a circular plane Wafer. Due to the pumping mode or the asymmetry of the reaction chamber 3, asymmetry in particle density, temperature and flux in the reaction chamber 3 is usually caused. The asymmetry of the gas flow causes an asymmetry of the plasma conductivity, and the asymmetry of the plasma conductivity leads to uneven deposition of power, which causes the ionization ionization unevenness. As the size of the wafer 5 increases, the volume of the reaction chamber 3 also increases correspondingly, and the edge and center plasma density distribution unevenness is more pronounced. Therefore, most of the etching equipments currently have the problem of uneven etching rate, which has a great adverse effect on the semiconductor manufacturing process.

In order to obtain a relatively uniform etching rate on the surface of the object to be etched, it is necessary to obtain a relatively uniform plasma density distribution over the wafer 5 in the reaction chamber 3, that is, to obtain a more uniform plasma above the wafer 5. Distribution to improve the quality of the etch.

As shown in Fig. 2, the conventional inductive coupling coil 4 has a planar spiral structure, and the plasma excited is very uneven. Since the inductive coupling coil has a strong electromagnetic field excited in the central portion of the reaction chamber, the plasma density generated in the center is high, and diffusion can be used to compensate for the low peripheral density region, which causes dependence on gas pressure. Very large, only in the range of Ι-lOmTorr (to) can have the best performance. This makes the process's adjustable window very small and imposes significant limitations on the semiconductor manufacturing process. When the plasma density distribution is uneven, the etch depth on the wafer or the deposition thickness of the material on the wafer is not uniform, which will reduce the yield of the device. In particular, when the size of the wafer is increased from 100 mm to 300 mm, the volume of the reaction chamber is correspondingly increased, and it is unrealistic to rely on diffusion to make the plasma density uniform.

In addition, when the diameter of the wafer reaches 300 mm, it is necessary to correspondingly increase the size of the inductive coupling coil and increase the volume of the plasma chamber for processing the wafer, thus requiring the thickness of the dielectric window 1 to be correspondingly increased. Otherwise, the dielectric window 1 will be difficult to withstand the pressure difference between the extra-atmospheric pressure outside the chamber and the vacuum in the chamber. However, the thickened dielectric window 1 reduces the coupling efficiency of the energy because the RF field does not have sufficient flux density to excite the plasma after penetrating the thick dielectric window 1. And, as the diameter of the wafer increases, the length of this traditional inductive coupling line diagram is also Increase, close to or exceed one-eighth of the wavelength of the RF excitation source. In this way, the transmission line effect on the inductively coupled coil is significant, resulting in significant current and voltage variations, resulting in a significant change in magnetic flux density in the plasma, resulting in a non-uniform plasma density, resulting in uneven workpiece processing.

On the other hand, as the size of the inductive coupling coil increases, its inductance increases accordingly, so that the voltage across the inductive coupling coil increases accordingly. Large voltages cause capacitive coupling between the inductively coupled coil and the plasma. Such capacitive coupling increases the kinetic energy of the ions, making it difficult to accurately control the processing, which increases the microloading effect of the wafer and reduces the yield of the device. In addition, ions with higher kinetic energy collide with the inner walls of the plasma chamber to cause particle contamination. Moreover, large inductance also causes unstable impedance matching and low coupling efficiency, and correspondingly increases the non-uniformity of radial plasma density. Summary of the invention

SUMMARY OF THE INVENTION The present invention is directed to solving the above technical problems in the prior art, and provides an inductive coupling coil and an inductive coupling device using the same. In the inductive coupling coil which is the core of the present invention, since the coil is formed by a plurality of branches and each branch is organically combined by the planar portion and the solid portion, the plasma is distributed over the wafer of the reaction chamber to make the wafer surface The difference in the rate of occurrence of the chemical reaction is small, and the etching rate is hooked, thereby improving the etching quality of the wafer. The inductive coupling device using the inductive coupling coil also has the characteristics of uniform plasma distribution, uniform etching rate and high etching quality.

According to one aspect of the present invention, the present invention provides an inductive coupling coil which is constructed by a plurality of identically-structured independent branch nests, the plurality of independent branch coaxial lines being arranged symmetrically with respect to an axis.

Wherein each of the independent branches includes a solid portion and a planar portion, the solid portion extending in an axial direction; the planar portion extending circumferentially along a plane perpendicular to the axis; a bottom end portion of the solid portion and a planar portion Internal endpoints are smoothly connected. Wherein, the planar portion of each of the individual branches is substantially concentric, and preferably, the planar portion of each of the branches includes a plurality of arcuate pattern forming portions, and at least one of the pattern forming portions extends and connects The connecting portion, the pattern forming portions respectively extend along concentric circles.

Wherein each of the pattern forming portions has a length ranging between about one-half circumference and one-quarter circumference.

Wherein, the solid portion of each of the independent branches is spirally raised along the axis. The solid portion of each of the individual branches has the same diameter or a smaller diameter or a larger diameter in the ascending direction.

The independent branch has n (n is an integer greater than or equal to 2).

According to another aspect of the present invention, the present invention further provides an inductive coupling device using the above inductive coupling coil, comprising a reaction chamber, a dielectric window is disposed on an upper portion of the reaction chamber, and an inductor is disposed on an upper portion of the dielectric window. A coupling coil, the inductive coupling coil is connected to the RF power source through a RF matching device.

The plurality of independent branches of the inductive coupling coil are connected in parallel with each other and connected to the radio frequency matching device.

Wherein each independent branch of the inductive coupling coil is respectively connected to the radio frequency matching device. Wherein, each independent branch of the inductive coupling coil is connected in parallel, and the input terminal connected in parallel is connected in series with a variable capacitor, and the output end is grounded through a grounding capacitor.

The input ends of each of the independent branches of the inductive coupling coil are respectively connected in series with variable capacitors, and then connected in parallel, and the output ends are grounded through a grounding capacitor.

It can be seen from the above technical solution provided by the present invention that since each branch of the inductively coupled coil provided by the present invention is a combination of a planar portion and a solid portion, and the solid portion is located in the middle, the structure makes the inductive coupling coil react The electric field generated in the middle of the chamber is smaller than the electric field generated at the corresponding position of the planar portion of the inductive coupling coil at the corresponding position in the chamber, thus solving the defects of the aforementioned prior art inductive coupling coil, so that the plasma is at the center and the edge of the chamber The distribution is more uniform.

Further, in the present invention, by symmetrical connection of the independent branches having substantially the same structure, the inductance of the inductive coupling coil is reduced, so that a large-area plasma can be easily obtained, and the uniformity of plasma in a large-area process can be improved. At the same time, the inductively coupled coil structure symmetrical the electromagnetic field distribution in the reaction chamber, which further makes the distribution of the plasma more uniform at the center and the edge. The plasma is distributed in the reaction chamber to make the chemical reaction on the surface of the etched material have a small difference in speed and uniform etching rate, thereby improving the etching quality of the wafer.

In addition, the inductive coupling device using the inductive coupling coil provided by the invention also has the characteristics of uniform plasma distribution in the reaction chamber, small difference in speed of chemical reaction on the surface of the object to be etched, and uniform etching rate, and thus The inductive coupling device performs processing such as etching to improve the etching quality of the wafer. DRAWINGS

1 is a schematic structural view of a prior art inductively coupled plasma device;

2 is a schematic structural view of a prior art inductive coupling coil;

3 is a perspective view showing a first embodiment of an inductive coupling coil of the present invention; FIG. 4 is a schematic plan view showing a first embodiment of the inductive coupling coil of the present invention; FIG. 6 is a perspective view showing a second embodiment of the inductive coupling coil of the present invention; FIG. 7 is a schematic structural view of the second embodiment of the inductive coupling coil of the present invention; FIG. 9 is a perspective view showing a third embodiment of the inductive coupling coil of the present invention; FIG. 10 is a perspective view showing a third embodiment of the inductive coupling coil of the present invention; FIG. 11 is a schematic plan view showing a third embodiment of the inductive coupling coil of the present invention; FIG. 12 is a schematic structural view of the first embodiment of the inductive coupling device of the present invention; Figure 13 is a schematic structural view of a second embodiment of the inductive coupling device of the present invention;

Figure 14 is a schematic view showing the structure of a third embodiment of the inductive coupling device of the present invention. detailed description

The inductive coupling coil provided by the present invention is composed of a plurality of independent branches having the same structure, and the plurality of independent branch coaxial lines are symmetrically arranged with respect to the axis. The details will be described below with reference to Figs. 3 to 11 .

As shown in Fig. 3, Fig. 4 and Fig. 5, the inductive coupling coil of the first embodiment of the present invention is composed of two independent branches of the same structure, and the two independent branches are coaxially arranged symmetrically with respect to the axis. Each of the individual branches includes a solid portion 10 and a planar portion 11, and the inner end of the planar portion 11 is smoothly connected to the bottom end of the solid portion 10.

Among them, the three-dimensional portion 10 extends in the axial direction, and specifically, the three-dimensional portion 10 can be spirally raised along the axis. The diameters of the spirals may be the same or different, for example, the diameter may be gradually smaller in the rising direction or the diameter may be gradually increased in the rising direction. Moreover, the pitch of the ascending spirals is not limited, and may be equally spaced; or may be unequal pitches, such as pitches becoming larger or smaller.

The planar portion 11 extends circumferentially along a plane perpendicular to the axis, in particular, the planar portion 11 of each individual branch is substantially concentric in shape, the planar portion of each branch includes a plurality of arcuate pattern forming portions, and at least one A connecting portion extending and connected between the pattern forming portions, the pattern forming portions respectively extending along concentric circles. The pattern forming portion is a portion of the plane portion 11 which constitutes a substantially concentric circle. In this embodiment, each of the pattern forming portions has a length of about one-half of a circumference.

As shown in FIG. 6, FIG. 7, and FIG. 8, the structural principle of the inductive coupling coil of the second embodiment of the present invention is the same as that of the first embodiment, and the difference between the two is that the inductive coupling coil in the first embodiment is Two independent branches of the same structure are nested, and the inductive coupling coil of the second embodiment is composed of three independent branches of the same structure. In the present embodiment, each of the pattern forming portions has a length of about one third of a circumference. As shown in FIG. 9, FIG. 10 and FIG. 11, the structural principle of the inductive coupling coil of the third embodiment of the present invention is the same as that of the first embodiment, and the difference therebetween is: the inductive coupling line in the first embodiment The two independent branches of the same structure are nested, and the inductive coupling line 第三 in the third embodiment is composed of four independent branches of the same structure. In the present embodiment, each of the pattern forming portions has a length of about a quarter of a circumference.

It can be understood that the number of independent branches included in the inductive coupling coil provided by the present invention is not limited to two, three or four as described in the above embodiments, but may theoretically be n, wherein n is any integer greater than or equal to 2. In fact, as long as n satisfies the aforementioned relationship and constitutes n independent branch coaxial lines of the aforementioned inductive coupling coil and is symmetrically arranged with respect to the axis.

The present invention also provides an inductive coupling device using the above-described inductive coupling coil, which will be described in detail below with reference to Figs.

Referring to 12 to 14, the inductive coupling device provided by the present invention comprises a reaction chamber 3, a chuck 9 for placing the wafer 5 is disposed in the reaction chamber 3, and a dielectric window 1 is provided on the upper portion of the reaction chamber 3, and a dielectric window is provided. The middle portion of 1 is provided with an intake port 2 through which the gas introduction device 8 introduces a process gas into the reaction chamber 3. An upper portion of the dielectric window 1 is provided with an inductive coupling coil 4, and an input end of the inductive coupling coil 4 is connected to an RF (radio frequency) source 7 through a matching device (ie, a radio frequency matching device) 12, and an output terminal of the inductive coupling coil 4 passes through a grounding capacitor. CO grounding. An induced electric field is generated in the reaction chamber 3, and the gas entering the reaction chamber 3 is excited into a plasma to perform etching or the like on the wafer 5.

In the device, a plurality of independent branches of the inductive coupling coil 4 are connected in parallel with each other, and the input terminals of the plurality of independent branches can be connected in series with a variable capacitor C1, and the impedance of each individual branch can be changed by changing the size of the variable capacitor C1. The grounding capacitor CO determines the position of the maximum and minimum current and voltage on the coil, so the current and voltage on each individual branch are adjustable. Thus, the plasma density distribution can be adjusted by adjusting the current ratio on each branch to further control plasma uniformity.

As shown in FIG. 12, in the first embodiment of the inductive coupling device provided by the present invention, inductive coupling A plurality of independent branches of the coil 4 are connected in parallel with each other and then connected to an RF (Radio Frequency) source 7 through a matcher 12.

As shown in FIG. 13, in the second embodiment of the inductive coupling device provided by the present invention, a plurality of independent branches of the inductive coupling coil 4 are connected in parallel with each other, and a variable capacitor C1 is connected in series at the input end, and then passed through the matching device 12. Connect to RF (radio frequency) source 7.

As shown in Fig. 14, in the third embodiment of the inductive coupling device provided by the present invention, the inductively coupled overmatcher 12 is connected to an RF (Radio Frequency) source 7.

As can be seen from the above description, since each branch of the inductively coupled coil provided by the present invention is a combination of a planar portion and a solid portion, and the solid portion is located in the middle, the structure is such that the inductive coupling coil is generated in the middle of the reaction chamber. The electric field is smaller than the electric field generated at the corresponding position of the planar portion of the inductive coupling coil at the corresponding position in the chamber, thus solving the defects of the aforementioned prior art inductive coupling coil, thereby making the distribution of the plasma more uniform at the center and the edge of the chamber.

Further, in the present invention, by symmetrical connection of the independent branches having substantially the same structure, the inductance of the inductive coupling coil is reduced, so that a large-area plasma can be easily obtained, and the uniformity of plasma in a large-area process can be improved. At the same time, this inductively coupled coil structure symmetrical the electromagnetic field distribution in the reaction chamber, which further makes the plasma distribution more uniform at the center and edge. The uniform distribution of the plasma in the reaction chamber will result in a small difference in the rate of chemical reaction on the surface of the material to be etched, and the etching rate is uniform, thereby improving the etching quality of the wafer.

It can be understood that the inductive coupling device using the inductive coupling coil provided by the invention also has the characteristics of uniform plasma distribution in the reaction chamber, small difference in speed of chemical reaction on the surface of the shield to be etched, and uniform etching rate. The etching process using such an inductive coupling device can improve the etching quality of the wafer.

It should be noted that the RF (radio frequency) source used in the present invention may be one or more. Further, a plurality of independent branches may be separately connected to the RF (Radio Frequency) source 7 through the matcher 12, respectively.

It should be further noted that the inductive coupling coil provided by the present invention and the inductive coupling device using the inductive coupling coil are mainly used for semiconductor wafer processing equipment, but are not limited thereto, and are also applicable to other devices.

The above is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or within the technical scope disclosed by the present invention. Alternatives are intended to be covered by the scope of the present invention.

Claims

Claim

An inductive coupling coil, characterized in that it is composed of a plurality of independent branches having the same structure, and the plurality of independent branch coaxial lines are arranged symmetrically with respect to the axis.

2. The inductive coupling coil according to claim 1, wherein each of said independent branches comprises a solid portion and a planar portion, said solid portion extending in an axial direction; said planar portion being along a plane perpendicular to the axis Extending to the periphery; the bottom end of the solid portion is smoothly connected to the inner end of the planar portion.

The inductive coupling coil according to claim 2, wherein the planar portion of each of the independent branches is substantially concentric.

4. The inductive coupling coil according to claim 3, wherein the planar portion of each of the branches includes a plurality of arcuate pattern forming portions, and at least one connecting portion extending and connected between the pattern forming portions The pattern forming portions respectively extend along concentric circles.

The inductive coupling coil according to claim 4, wherein each of said pattern forming portions has a length ranging between about one-half circumference and one quarter circumference.

The inductive coupling coil according to any one of claims 1 to 5, characterized in that the solid portion of each of the individual branches is spirally raised along the axis.

7. The inductive coupling coil according to claim 6, wherein the three-dimensional portion of each of the individual branches has the same diameter or a decreasing diameter or a diameter of the spiral in the ascending direction.

The inductive coupling coil according to any one of claims 1 to 5, wherein the independent branch has n (n is an integer greater than or equal to 2).

The inductive coupling coil according to claim 6, wherein said independent branch has n (n is an integer greater than or equal to 2).

10. An inductive coupling device using the inductive coupling coil according to any one of claims 1 to 9, comprising a reaction chamber, a dielectric window is disposed on an upper portion of the reaction chamber, wherein an upper portion of the dielectric window is provided There is an inductive coupling coil, and the inductive coupling coil is connected to the RF power source through a radio frequency matcher.

11. The inductive coupling device according to claim 10, wherein the plurality of independent branches of the inductive coupling coil are connected in parallel with each other and connected to the radio frequency matching device.

12. The inductive coupling device of claim 10, wherein each of the independent branches of the inductive coupling coil is coupled to the RF matcher.

The inductive coupling device according to any one of claims 10 to 12, wherein each of the independent branches of the inductive coupling coil is connected in parallel, and the input terminal connected in parallel is connected in series with a variable capacitor, and the output end is grounded. The capacitor is grounded.

The inductive coupling device according to any one of claims 10 to 12, wherein the input ends of each of the independent branches of the inductive coupling coil are respectively connected in series with variable capacitors, and then connected in parallel, and the output ends are passed through Ground capacitor is grounded.