TW201338005A - Power supply system for regulating electric field distribution of plasma processing chamber - Google Patents

Abstract

The present invention discloses a power supply system for regulating electric field distribution of plasma processing chamber. The power supply system is located between a radio frequency power source and a lower electrode, and comprises a first power distribution circuit and a second power distribution circuit. The first power distribution circuit and the second power distribution circuit are connected to different contacts on the lower electrode. Two sets of stationary waves with different shapes are formed on the lower electrode. The regulation of phases and voltage amplitudes for the two sets of stationary waves can be realized by regulating the phase regulators and the adjustable capacitors on the two power distribution circuits, and thus the electric field distribution uniformity on the lower electrode may be regulated, such that the electric field distribution of the lower electrode may satisfy the requirements for different types of plasma processing, and better accomplish the processing of the substrate to be processed.

Description

Power supply system for adjusting electric field distribution of plasma processing chamber

The invention relates to the field of electric field distribution regulation of a plasma processing chamber, in particular to a power supply system capable of realizing an adjustable electric field uniformity in a plasma processing chamber.

In the plasma processing chamber, generally including a cylindrical or other shaped reaction chamber, a lower electrode for placing the substrate to be processed is disposed at the bottom of the reaction chamber, and an upper electrode is disposed at the top of the reaction chamber, The upper electrode is disposed opposite to the lower electrode and forms a plasma generating space therebetween. By applying a radio frequency voltage between the upper electrode and the lower electrode, a gas that is introduced into the reaction chamber forms a plasma, and thus can be placed on the lower electrode. The substrate to be processed is processed.

The electromagnetic field formed between the upper electrode and the lower electrode causes the low-pressure reaction gas to be ionized to generate a plasma, and whether the electromagnetic field intensity is uniformly distributed determines whether the plasma can be uniformly distributed in the reaction chamber, thereby determining the substrate to be processed. Whether it can be treated uniformly; therefore, the uniform distribution of the electromagnetic field between the upper and lower electrodes is a key factor determining whether the processing of the substrate to be processed is uniform. The commonly used radio frequency voltage is usually applied to the lower electrode, and the RF power source is connected to the center position of the lower electrode through a matching network to form an electromagnetic field above the lower electrode. However, due to the high frequency of the RF power source, it is usually a high-frequency power source, which easily forms a standing wave above the lower electrode and destroys the uniformity of the electromagnetic field. Therefore, the processing of the substrate to be processed is not uniform and cannot meet the needs of production.

In order to solve the above technical problems, the present invention provides a power supply system for adjusting the electric field distribution in a plasma processing chamber.

The Summary of the Invention provides only basic aspects of some aspects and features of the present invention. The introductory description, rather than the general summary of the invention, is not intended to be construed as limiting or limiting the scope of the invention. The preamble described in more detail below.

The invention discloses a power supply system for adjusting the electric field uniformity in a plasma processing chamber. The plasma processing chamber includes an upper electrode and a lower electrode, and the power supply system is connected to one of the lower electrode or the upper electrode. Between the RF power sources, wherein the power supply system comprises: a matching network connecting the RF power source; a phase adjuster for adjusting the phase of the input signal; and a tunable capacitor for distributing the input power; The output of the matching network includes a first power distribution circuit and a second power distribution circuit, and the phase adjuster and the adjustable capacitor are selected from the first power distribution circuit and the One of the two power distribution circuits or the two circuits; the first power distribution circuit output is electrically connected to a central area of the electrode to which the power supply system is connected, and the second power distribution circuit has a plurality of outputs a plurality of electrical connection points with the electrodes connected to the power supply system, the plurality of electrical connection points forming one or more of the same as the center of the electrode connected to the power supply system Concentric circles, the distance between adjacent two electrical connection points is equal to the plurality of electrical connection points are located on the same concentric circles.

The phase adjuster may be located on the first power matching circuit and electrically connected to a central area of the electrode to which the power supply system is connected. The adjustable capacitor is located on the second power matching circuit, and the electrode connected to the power supply system has Multiple electrical connection points.

The adjustable capacitor can also be located on the first power matching circuit, and the power supply The central region of the electrode to which the system is connected is electrically connected. The phase adjuster is located on the second power matching circuit and has a plurality of electrical connection points with the electrode connected to the power supply system.

The adjustable capacitor and the phase adjuster can also be located on the first power matching circuit at the same time, and are electrically connected to a central area of the electrode connected to the power supply system, and the second power matching circuit and the electrode connected to the power supply system have Multiple electrical connection points.

The first power matching circuit is further electrically connected to a central region of an electrode to which the power supply system is connected, and the adjustable capacitor and the phase adjuster are located on the second power matching circuit, and the electrode connected to the power supply system There are multiple electrical connection points.

The second power matching circuit and the electrode connected to the power supply system may have three electrical connection points, and the distance from the concentric circle of the three electrical connection points to the center of the electrode connected to the power supply system is less than or equal to the power supply system. The radius of the connected electrode; the distance between two adjacent points of the three electrical connection points is equal to each other.

The second power matching circuit may also have four electrical connection points with the electrodes connected to the power supply system, and the distance from the concentric circle of the electrical connection point to the center of the electrode connected to the power supply system is less than or equal to the connection of the power supply system. The radius of the electrodes is equal to the distance between two adjacent points of the four electrical connection points.

The second power matching circuit may further have more than six electrical connection points with the electrodes connected to the power supply system, and the electrical connection points may be located on one or more concentric circles, and the output ends of the second power matching circuit are The distances of the electrical connection points in the same concentric circle are equal, the distance between two adjacent points of the electrical connection points on the same concentric circle is equal, and the number of electrical connection points on one concentric circle is at least three.

The matching network output terminal may further include a third power distribution circuit, the third power distribution circuit including a plurality of outputs connected to the power supply system The electrodes have a corresponding number of electrical connection points, the electrical connection points being evenly distributed over one or more concentric circles of the electrodes, and at least three electrical connection points on each concentric circle.

The phase adjuster is an adjustable length wire, and the phase of the output potential is adjusted by adjusting the length of the wire. The frequency of the RF power source is greater than 60 MHz.

The invention has the advantages that the output of the matching network is divided into a first power distribution circuit and a second power distribution circuit, and then respectively connected to a central area and a peripheral area of the electrode connected to the power supply system, so that the power supply system is connected A plurality of standing waves superimposed on each other are formed on the electrodes, and phase and voltage amplitudes of the two sets of standing waves are adjusted by adjusting phase adjusters and adjustable capacitors on the two power distribution circuits, thereby solving the RF in the prior art. The output of the power source only connects the standing wave effect brought by the point of the lower electrode, so that the uniformity of the electric field distribution on the lower electrode can be adjusted, so that the electric field distribution of the lower electrode satisfies the needs of various plasma processing, and better Finish processing of the substrate to be processed.

The drawings, which are included in the specification, are exemplary embodiments of the invention The drawings are intended to illustrate the main features of the described embodiments. The figures are not intended to describe each feature of the actual embodiments and the relative dimensions of the depicted elements, which are not drawn to scale.

1 is a schematic view showing the structure of a plasma processing chamber according to the present invention. The plasma processing chamber 100 includes a lower electrode 3 for supporting a substrate 11 to be processed and an upper electrode 10 above the lower electrode 3. The upper electrode 10 is connected to the reaction gas source 110 on one side of the back electrode 3, and the small surface of the upper electrode 10 facing the lower electrode 3 is provided with a small hole allowing the reaction gas to pass therethrough. The reaction gas source 110 The reaction gas is introduced into the reaction region 200 formed by the upper electrode 10 and the lower electrode 3 by the control valve 111.

The lower electrode 3 is connected to a radio frequency power source 5, and the radio frequency power source supplies radio frequency power to the plasma processing chamber, so that the reaction gas in the reaction region 200 is ionized to generate plasma, and the plasma processing substrate 11 is processed.

The upper electrode 10 and the lower electrode 3 of the embodiment are circular, and one of the upper electrode 10 and the lower electrode 3 is connected to the RF power source 5, and the power supply system is connected to the RF power source 5. The present embodiment uses the lower electrode 3 and the RF power source. A solution for connecting the power supply system between 5. The power supply system includes: a matching network 4 connected to an output of the RF power source 5; a phase adjuster 2 for adjusting the phase of the input signal; and a tunable capacitor 1 for distributing the input power. The output of the matching network 4 comprises a first power distribution circuit and a second power distribution circuit, the phase adjuster 2 and the adjustable capacitance 1 being located on a circuit or two circuits selected from the first power distribution circuit and the second power distribution circuit In this embodiment, the phase adjuster 2 is located on the first power distribution circuit and is electrically connected to the central region of the lower electrode 3. The adjustable capacitor 1 is located on the second power distribution circuit and has multiple electrical connection points with the lower electrode 3. The electrical connection points establish one or more concentric circles identical to the center of the lower electrode 3, and the distance between adjacent two electrical connection points on a concentric circle is equal to each other. In this embodiment, the second power distribution circuit where the adjustable capacitor 1 is located has three electrical connection points with the lower electrode 3, which are respectively A1, A2, and A3, and are located on a concentric circle. The distance from the concentric circle to the center of the three electrical connection points is equal to the radius of the lower electrode 3. The distance from the output end of the second power distribution circuit to the three electrical connection points of the lower electrode 3 is equal, so that the phases of the points A1, A2, and A3 are the same.

In this embodiment, the matching network 4 is divided into a first power distribution circuit and a second distributed power circuit at point C. By adjusting the size of the adjustable capacitor 1, the A point and the respectively passed through the first power distribution circuit are controlled. Power distribution through the second distribution The power of point B of the road. The phase adjuster 2 can adjust the phase of point B. Since the paths are equal, the phases of the three points A1, A2, and A3 must be in phase.

It can be assumed that the voltages at three points A1, A2, and A3 are: A1 = A2 = A3 = f1 (c) cos( ω t), where ω is the frequency and f1 (c) is a function related to the size of the capacitor.

The voltage at point B is B = f2 (c) cos( ω t + Φ), and f2 (c) is also a function related to the magnitude of the capacitance, and Φ is adjusted according to the phase adjuster 2.

Any point D(X, Y) above the lower electrode 3 can be regarded as the phase superposition of four points A1, A2, A3, B. It is assumed that the voltage at point D is: V(D)=f1(c)*cos(ωt+ Fa(D))+f2(c)*cos(ωt+fb(D)+Φ) where fa(D) represents the function of the distance from A1, A2, A3 to point D, and fb(D) represents point B. The function of the distance to point D, f1(c)*cos( ω t+fa(D)) represents the function of the standing wave generated by the three-point electrodes of A1, A2, A3, f2(c)*cos( ω t +fb(D)+Φ) represents a function of the standing wave generated by the B-point electrode, and the voltage amplitude and phase of the two sets of standing waves are both adjustable, since the two sets of standing wave shapes are different, The group standing waves are superimposed together, and the voltage amplitude and phase difference of the two sets of standing waves are adjusted to realize the uniformity of the electric field on the lower electrode 3. The voltage amplitude and phase of the two sets of standing waves can be achieved by adjusting the adjustable capacitor 1 and the phase adjuster 2. The phase adjuster 2 described in this embodiment is a wire whose length can be adjusted, and the output potential phase adjustment is realized by adjusting the length of the wire.

When the input wavelength of the RF power source used in this embodiment is 1000 mm, the adjustable capacitance and the phase difference Φ are respectively taken as fixed values for simulation, and the obtained electric field distribution curve is shown in FIG. 3 and FIG. 4 . 3 shows the power supply system of the present invention when the phase difference Φ is π, when the two power distribution circuits PA:PB are 0:1, 0.5:1, 1:1, 10:1, and 10000:1, respectively. Electric field distribution simulation diagram; FIG. 4 shows the power supply system of the present invention when the two-way power distribution circuit PA:PB is 1:1, The electric field simulation diagram when the phase difference Φ is 0, π/8, π/4, π/2, and π.

The second power distribution circuit of the present invention may have four output ends, and the corresponding lower electrode 3 has four electrical connection points, four electrical connection points are distributed on one concentric circle, and the output end of the second power distribution circuit The distance between the four electrical connection points is equal, and the distance between two adjacent points of the four electrical connection points is equal to each other. The principle of adjusting the electric field is the same as described above.

The second power distribution circuit of the present invention may further have more than six output terminals, and the lower electrode 3 has a corresponding number of electrical connection points. When all the electrical connection points are located on the same concentric circle of the lower electrode 3, The distance from the output end of the second power distribution circuit to all electrical connection points is equal, and the distance between two adjacent electrical connection points is equal to each other; the plurality of electrical connection points may also be located on different concentric circles, each concentric circle The upper electrical connection points are at least three, the distances from the output ends of the second power distribution circuit to the electrical connection points on the same concentric circle are equal, and the distances between adjacent electrical connection points on the same concentric circle are equal.

The matching network output end of the present invention may further comprise a third power distribution circuit, the third power distribution circuit comprising a plurality of output ends, and a corresponding number of electrical connection points with the lower electrode 3, the electrical connection point Uniformly distributed on one or more concentric circles of the electrode, the electrical connection point on each concentric circle is at least three.

The power supply system of the present embodiment can also be connected between the RF power source 5 and the upper electrode 10. The specific working principle is the same as the above embodiment.

The phase adjuster 2 and the adjustable capacitor 1 are respectively located outside the first power distribution circuit and the second power distribution circuit, and the positions of the adjustable capacitor 1 and the phase adjuster 2 are interchangeable or may be located at the same time. One of the power distribution circuit and the second power distribution circuit operates on the same principle as the above embodiment.

The present invention has been described with reference to the specific embodiments, and all aspects thereof should be Illustrative rather than limiting. In addition, other embodiments of the invention will be apparent to those skilled in the <RTIgt; Different aspects and/or elements of the described embodiments may be used alone or in any combination in the plasma processing chamber field. The above specific embodiments are to be considered as illustrative only, and the scope and spirit of the invention are defined by the scope of the claims.

100‧‧‧ Plasma processing chamber

110‧‧‧Responsive gas source

111‧‧‧Control valve

200‧‧‧Reaction area

10‧‧‧Upper electrode

11‧‧‧Substrate to be processed

1‧‧‧ adjustable capacitor

2‧‧‧ phase adjuster

3‧‧‧ lower electrode

4‧‧‧matching network

5‧‧‧RF power source

A‧‧‧ points

A1‧‧‧Electrical connection point

A2‧‧‧ electrical connection point

A3‧‧‧Electrical connection point

B‧‧‧ points

1 is a schematic structural view of a plasma processing chamber according to the present invention; FIG. 2 is a schematic diagram showing the circuit connection of the power supply system according to the present invention; and FIG. 3 is a diagram showing the power supply system of the present invention having a phase difference Φ of π. At the same time, the electric field distribution simulation diagram of the two-way power distribution circuit at different power ratios; FIG. 4 shows a simulation diagram of the electric field distribution with different phase differences Φ when the power of the two power distribution circuits is equal in the power supply system of the present invention.

1‧‧‧ adjustable capacitor

2‧‧‧ phase adjuster

3‧‧‧ lower electrode

4‧‧‧matching network

5‧‧‧RF power source

A‧‧‧ points

A1‧‧‧Electrical connection point

A2‧‧‧ electrical connection point

A3‧‧‧Electrical connection point

B‧‧‧ points

Claims (12)

A power supply system for adjusting an electric field uniformity in a plasma processing chamber, the plasma processing chamber including an upper electrode and a lower electrode, the power supply system being connected between the lower electrode and the upper electrode and an RF power source, The power supply system includes: a matching network connected to the RF power source; a phase adjuster for adjusting the phase of the input signal; and a tunable capacitor for distributing the input power; the output end of the matching network includes a a first power distribution circuit and a second power distribution circuit, the phase adjuster and the adjustable capacitor being located on one or both of the first power distribution circuit and the second power distribution circuit; An output end of the power distribution circuit is electrically connected to a central area of the electrode to which the power supply system is connected, and the second power distribution circuit has a plurality of output ends, and the plurality of electrical connection points are connected to the electrode connected to the power supply system, the plurality of electricity The connection point constitutes one or more concentric circles identical to the center of the electrode to which the power supply system is connected, among the plurality of electrical connection points on the same concentric circle O two electrical connection points equal distance. The power supply system of claim 1, wherein the phase adjuster is located on the first power matching circuit, and is electrically connected to a central area of an electrode to which the power supply system is connected, the adjustable capacitor is located at the second power On the matching circuit, the electrodes connected to the power supply system have a plurality of electrical connection points. The power supply system of claim 1, wherein the adjustable capacitor is located on the first power matching circuit, and is electrically connected to a central area of an electrode to which the power supply system is connected, and the phase adjuster is located in the second power On the rate matching circuit, the electrodes connected to the power supply system have a plurality of electrical connection points. The power supply system of claim 1, wherein the adjustable capacitor and the phase adjuster are located on the first power matching circuit, and are electrically connected to a central area of an electrode to which the power supply system is connected, the second power The matching circuit has a plurality of electrical connection points with the electrodes connected to the power supply system. The power supply system of claim 1, wherein the first power matching circuit is electrically connected to a central region of an electrode to which the power supply system is connected, and the adjustable capacitor and the phase adjuster are located in the second power matching circuit. The electrode connected to the power supply system has a plurality of electrical connection points. The power supply system of any one of claims 1 to 5, wherein the second power matching circuit has three electrical connection points with electrodes connected to the power supply system, and concentric circles of the three electrical connection points The distance from the center of the electrode to which the power supply system is connected is less than or equal to the radius of the electrode to which the power supply system is connected; the distance between two adjacent points of the three electrical connection points is equal to each other. The power supply system according to any one of claims 1 to 5, wherein the second power matching circuit and the electrode connected to the power supply system have four electrical connection points, and the concentric circles of the electrical connection point are The distance between the centers of the electrodes to which the power supply system is connected is less than or equal to the radius of the electrodes to which the power supply system is connected, and the distance between two adjacent points of the four electrical connection points is equal to each other. The power supply system according to any one of claims 1 to 5, wherein the second power matching circuit has more than six electrical connection points with electrodes connected to the power supply system, and the electrical connection point may be located. On a concentric circle, the electrical connection in the concentric circle at the output of the second power matching circuit The distance between the contacts is equal, and the distance between adjacent electrical connection points on the electrical connection points on the concentric circles is equal. The power supply system according to any one of claims 1 to 5, wherein the second power matching circuit has more than six electrical connection points with electrodes connected to the power supply system, and the plurality of electrical connection points are located On different concentric circles, the electrical connection points on each concentric circle are at least three, and the distance from the output end of the second power distribution circuit to the electrical connection points on the same concentric circle is equal, adjacent on the same concentric circle The distance between the electrical connection points is equal to each other. The power supply system of claim 1, wherein the output of the matching network further comprises a third power distribution circuit, the third power distribution circuit includes a plurality of outputs, and the electrodes connected to the power supply system have Corresponding number of electrical connection points, the electrical connection points are evenly distributed on more than one concentric circle of the electrode, and the electrical connection points on each concentric circle are at least three. The power supply system of claim 1, wherein the frequency of the RF power source is greater than 60 MHz. The power supply system of claim 1, wherein the phase adjuster is an adjustable length wire, and the phase of the output potential is adjusted by adjusting the length of the wire.