CN112786420B

CN112786420B - Plasma processing device and method for processing substrate by using same

Info

Publication number: CN112786420B
Application number: CN201911081973.1A
Authority: CN
Inventors: 连增迪; 赵馗; 黄允文
Original assignee: Advanced Micro Fabrication Equipment Inc Shanghai
Current assignee: Advanced Micro Fabrication Equipment Inc Shanghai
Priority date: 2019-11-07
Filing date: 2019-11-07
Publication date: 2023-03-07
Anticipated expiration: 2039-11-07
Also published as: CN112786420A; TWI775166B; TW202119467A

Abstract

The present invention provides a plasma processing apparatus, including: the device comprises a reaction cavity, a substrate, an insulating material window and an inductance coil, wherein the base is arranged below the reaction cavity, the substrate to be processed is arranged on the base, the top of the reaction cavity comprises the insulating material window, and the inductance coil is arranged above the insulating material window; a cavity for containing a metal liquid; a source radio frequency power supply device; biasing a radio frequency power supply; an actuating device for extracting the metal liquid from the cavity or injecting the metal liquid into the cavity; and the controller is connected to the source radio frequency power supply device, the bias radio frequency power supply and the actuating device and is used for controlling the source radio frequency power supply device and the bias radio frequency power supply to input radio frequency power to the reaction cavity and controlling the actuating device to extract or inject metal liquid into the cavity. The invention also provides a method of processing a substrate.

Description

Plasma processing device and method for processing substrate by using same

Technical Field

The present invention relates to plasma processing apparatuses, and more particularly, to an inductively coupled plasma processing apparatus and a method for processing a substrate using the same.

Background

In recent years, with the development of semiconductor manufacturing processes, the requirements for integration and performance of elements have been increased, and Plasma Technology (Plasma Technology) has been widely used. The plasma technology is to introduce reaction gas into a reaction chamber of a plasma processing apparatus and introduce electron current, accelerate electrons by using a radio frequency electric field, and generate plasma by ionizing the reaction gas by colliding with the reaction gas, and the generated plasma can be used for various semiconductor manufacturing processes, such as a deposition process (e.g., chemical vapor deposition), an etching process (e.g., dry etching), and the like.

The plasma processing apparatus includes common capacitively-coupled and inductively-coupled plasma processing devices. The capacitive coupling plasma processing device generates plasma in a reaction cavity by a radio frequency (direct current) power supply applied to a polar plate in a capacitive coupling mode to etch a substrate. Generally, the ion energy of the plasma generated by means of capacitive coupling is large, reaching 100-1000eV. The capacitively coupled plasma processing apparatus is used for dielectric etching in many cases. The inductively coupled plasma processing apparatus generates plasma for etching a substrate by introducing energy of a radio frequency power source into the interior of a reaction chamber through an induction coil in the form of magnetic field coupling. The ion energy of the plasma generated by the inductive coupling mode is about 10-100eV, which is mostly used for etching silicon materials.

Disclosure of Invention

In one aspect, the present invention provides a plasma processing apparatus comprising: the device comprises a reaction cavity, a substrate, an insulating material window and an inductance coil, wherein the base is arranged below the reaction cavity, the substrate to be processed is arranged on the base, the top of the reaction cavity comprises the insulating material window, and the inductance coil is arranged above the insulating material window; a cavity disposed within the insulating material window, the cavity for containing a metal liquid; the source radio frequency power supply device is used for applying a source radio frequency signal to the induction coil and/or the metal liquid in the cavity; a bias radio frequency power supply for applying a bias radio frequency signal to the pedestal; actuating means for withdrawing the molten metal from or injecting the molten metal into the cavity; and the controller is connected to the source radio frequency power supply device, the bias radio frequency power supply and the actuating device and is used for controlling the source radio frequency power supply device and the bias radio frequency power supply to input radio frequency power to the reaction cavity and controlling the actuating device to extract or inject metal liquid into the cavity.

Optionally, the source rf power supply means comprises an inductively coupled rf power supply coupled to the inductive coil and a capacitively coupled rf power supply coupled to the metallic liquid within the cavity of the insulating material window.

Optionally, the source rf power supply device includes a source rf power supply and a power divider, and the power divider is configured to divide rf power output by the source rf power supply to the inductor coil and the cavity of the insulating material window.

Optionally, the magnetic field generated by the inductor coil above the insulating material window entirely enters the cavity via the insulating material window.

Optionally, a portion of a magnetic field generated by the inductive coil above the insulating material window enters the cavity through the insulating material window, and another portion of the magnetic field enters the reaction chamber through the insulating material window.

Optionally, the actuating means comprises a pump for drawing the metallic liquid at least partially into the cavity from the reservoir or at least partially into the reservoir from the cavity.

In another aspect, the present invention provides a method of processing a substrate in a plasma processing apparatus, comprising: introducing a process gas into the reaction chamber; injecting a metal liquid into a cavity in an insulating material window at the top of the reaction chamber; feeding radio frequency power into the cavity through a source radio frequency power supply device; feeding radio frequency power into an inductance coil above the insulating material window through a source radio frequency power supply device; and pumping the metal liquid into the liquid storage device from the cavity, and stopping the radio-frequency power supply device from feeding radio-frequency power into the cavity.

Optionally, the method further comprises: RF power is simultaneously fed into the inductive coil above the insulating material window and the cavity in the insulating material window by a source RF power supply device to ignite plasma.

Optionally, the method further comprises: radio frequency power is fed into the induction coil above the insulating material window through a source radio frequency power supply device, and meanwhile, the metal liquid is pumped into the liquid storage device from the cavity.

Optionally, the method further comprises: and inputting bias radio frequency power to the base through the bias radio frequency power supply.

Drawings

Fig. 1 is a schematic structural diagram of an inductively coupled plasma processing apparatus according to the prior art.

Fig. 2 is a schematic structural view of a plasma processing apparatus according to an embodiment of the present invention.

Fig. 3 a-3 b show schematic views of different embodiments of the cavity in the processing device of fig. 2.

Fig. 3c shows a schematic cross-sectional view of a cavity of a further embodiment in the processing device of fig. 2.

Fig. 4 is a schematic structural view of a plasma processing apparatus according to another embodiment of the present invention.

Fig. 5-7 are flow diagrams of methods of processing a substrate according to embodiments of the invention.

Detailed Description

In order to make the contents of the present invention more comprehensible, the present invention is further described below with reference to the accompanying drawings. The invention is of course not limited to this particular embodiment, and general alternatives known to those skilled in the art are also covered by the scope of the invention.

Fig. 1 shows a schematic structure of an inductively coupled plasma processing apparatus in the prior art, in the schematic structure shown in fig. 1, the inductively coupled plasma processing apparatus includes a vacuum reaction chamber 100', the vacuum reaction chamber includes a substantially cylindrical reaction chamber sidewall 105' made of a metal material, an insulating material window 130 'is disposed above the reaction chamber sidewall 105', an inductor coil 140 'is disposed above the insulating material window 130', and the inductor coil 140 'is connected to a source rf power source 145'. Optionally, a heater layer 170' may be disposed between the insulating material window 130' and the induction coil 140 '. The side wall 105' of the reaction chamber has a gas injection port 150' at one end adjacent to the insulating material window 130', and the gas injection port 150' is connected to the gas supply device 10'. A susceptor 110' is disposed at a downstream position of the vacuum reaction chamber 100', and an electrostatic chuck 115' is disposed on the susceptor 110' for supporting and fixing the substrate 120 '. An exhaust pump 125 'is further disposed below the vacuum reaction chamber 100' for exhausting the reaction by-products out of the vacuum reaction chamber.

Before the process begins, the substrate 120 'is transferred to the electrostatic chuck 115' above the susceptor, and the reaction gas in the gas supply apparatus 10 'is introduced into the vacuum reaction chamber through the gas injection port 150', and then the source rf power source 145 'is applied to the induction coil 140'. In the conventional technology, the inductive coupling coil is a multi-turn coil structure, and the high-frequency alternating current outputted from the source rf power source 145 'after flowing through the coupling coil will generate a varying magnetic field passing through the insulating material window 130', and the varying magnetic field will generate a varying electric field in the vacuum reaction chamber 100', so that the reaction gas in the chamber is ionized to generate the plasma 160'. The plasma 160' contains a large number of active particles such as electrons, ions, excited atoms, molecules, and radicals, which can react with the surface of the substrate to be processed in various physical and chemical ways, so that the topography of the substrate surface is changed, i.e., the etching process is completed. In a plasma etching process, a source power source 145' is applied to the inductive coupling coil assembly 140' to primarily control plasma dissociation or plasma density, and a radio frequency bias power source 146' applies bias power to the pedestal 110' through a matching network 200', which acts to control ion energy and its energy distribution.

In an inductively coupled plasma processing apparatus, the changing magnetic field produced by the inductive coil generates a changing electric field within the reaction chamber that causes the gas within the reaction chamber to ionize into a plasma. The electric field is distributed in a spiral shape in a plane parallel to the insulating material window, and the electrons are promoted to move in a spiral shape. Due to the short electron motion path, it is not easy to ignite plasma under low pressure and low power conditions. Therefore, it is necessary to first ignite the plasma under high pressure and high power conditions and then switch to low pressure and low power to process the substrate. The sudden switching from high pressure high power to low pressure low power can easily affect the etching morphology of the substrate.

For the above reasons, the inventors thought that plasma could be generated by capacitive coupling, which is a method of generating a high electric field between upper and lower electrodes, causing electrons to move between the upper and lower electrodes, and striking gas molecules to generate plasma. The electron movement path in this manner is long and the plasma can be ignited even at low gas pressure and low radio frequency power. And after the plasma is generated, switching to an inductive coupling mode to maintain the plasma, and etching the substrate. The plasma generating mode of the invention combines an inductive coupling mode and a capacitive coupling mode, can generate plasma under the same air pressure and power and carry out substrate etching, avoids igniting the plasma under the conditions of high air pressure and high power, and then switches to low air pressure and low power to process the substrate.

Fig. 2 is a schematic configuration diagram of a plasma processing apparatus according to an embodiment of the present invention. In this processing apparatus, a cavity 132 for containing a metal liquid to serve as an upper electrode in a capacitive coupling manner is provided in an insulating material window 130. The metal liquid may be a pure metal such as mercury, or may be an alloy containing mercury or an alloy of alkali metals. The cavity 132 has a variety of shapes. Fig. 3 a-3 b show schematic views of different embodiments of the cavity 132 in the processing device of fig. 2. The cavity 132a may be cylindrical in shape with a horizontal cross-section as shown in fig. 3 a. The volume of the cavity 132a occupying the volume of the insulating material window 130 may be varied according to the requirements of different processes, i.e., the area of the upper electrode is changed, so that the magnetic field generated by the upper inductor 140 enters the cavity 132a either completely or partially, or the cavity 132a partially enters the lower reaction chamber. Fig. 3b shows a schematic cross-sectional view of another embodiment of the cavity 132 b. The cavity 132b is formed by a plurality of centrally connected segments, with adjacent segments being separated by windows 130 of insulating material. Fig. 3c shows a schematic cross-sectional view of a cavity 132c of a further embodiment. The cavity has a spiral wound configuration with an inner coil portion spaced from an outer coil portion by a window 130 of insulating material. When the inductor coil 140 above the insulating material window 130 is fed with rf current, the magnetic field generated by the inductor coil 140 enters the insulating material window 130 and the

cavities

132a, 132b, 132c. For the cavity 132a shown in fig. 3a, the magnetic fields enter the cavity 132a through the insulating material window 130, and due to the metal liquid introduced into the cavity 132a, the magnetic fields end up in the cavity 132a and do not enter the lower reaction chamber 100. With respect to the

cavities

132b and 132c shown in fig. 3b and 3c, since the adjacent sector portions of the cavity 132b are separated by the insulation material window 130 and the inner winding portion and the outer winding portion of the cavity 132c are separated by the insulation material window 130, a part of the magnetic field generated by the inductor coil 140 is terminated in the

cavities

132b and 132c, and another part of the magnetic field can enter the lower reaction chamber 100 through the insulation material windows 130, that is, a part of the magnetic field generated by the inductor coil 140 can enter the reaction chamber through the insulation material window 130. Several embodiments of the cavity 132 are exemplarily described above. It is noted that the cavity 132 may also have other shapes to completely or partially block the magnetic field generated by the inductor coil 140.

The source rf power supply 180 is connected to the inductor 140 and the cavity 132 in the insulating material window 130, and feeds rf power of high frequency, which may be 60MHz or 27MHz, to the inductor 140 and the metal liquid in the cavity 132 to ignite plasma. When the source rf power supply device 180 feeds the high-frequency rf power into the inductive coil 140, the plasma is ignited in an inductive coupling manner; when the source rf power supply 180 feeds rf power into the metal liquid in the cavity 132, the plasma is ignited by capacitive coupling. In this embodiment, the source rf power supply device 180 includes two rf power supplies: an inductively coupled rf power supply 1801 and a capacitively coupled rf power supply 1802 are connected to the inductive coil 140 and the cavity 132 in the insulating material window 130, respectively.

The actuating means 190 is used to withdraw the molten metal from the cavity 132 and to inject the molten metal into the cavity 132. In this embodiment, the actuation device 190 includes a pump 1901 and a reservoir 1902. Prior to igniting a plasma in reaction chamber 100, pump 1901 injects a metallic liquid from reservoir 1902 into cavity 132. After ignition of the plasma, pump 1901 draws the metal liquid from cavity 132 partially or completely back into reservoir 1902. A bias rf power supply 146 is coupled to the pedestal 110 to provide low frequency (e.g., 2MHz or 13.56 MHz) bias rf power for the etching process. In one embodiment, the bias rf power supply 146 applies a bias power to the pedestal 110 through the matching network 200, the bias power supply 146 acting to control the ion energy and its energy distribution.

The controller 250 is connected to the source rf power supply 180, the bias rf power supply 146, and the actuator 190 for controlling the feeding of rf power into the reaction chamber 100 and the flow of the metal liquid between the cavity 132 and the reservoir 1902. As will be described in more detail below.

Fig. 4 is a schematic structural view of a plasma processing apparatus according to another embodiment of the present invention. Which is different from the plasma processing apparatus of fig. 2 in that a source rf power supply apparatus 180. In this embodiment, the source rf power supply device 180 includes a source rf power supply 1803 and a power splitter 1804, the power splitter 1804 being used to split the rf power output by the source rf power supply 180 to the inductive coil 140 and the cavity 132 of the window of insulating material. The controller 250 may be used to adjust the distribution of rf power from the power splitter 1804 to the inductive coil 140 and the cavity 132, depending on actual demand. For example, the power divider 1804 distributes 50% of the rf power to the inductive coil 140 and 50% of the rf power to the cavity 132. Alternatively, the power divider 1804 distributes 40% of the rf power to the inductive coil 140 and 60% of the rf power to the cavity 132.

Fig. 5 shows a flow diagram of a method of processing a substrate according to one embodiment of the invention. For example, the substrate is processed by the plasma processing apparatus shown in fig. 2. Substrate 120 is placed on electrostatic chuck 115. The substrate 120 may be monocrystalline silicon, gallium arsenide, silicon carbide, gallium nitride, zinc oxide, or the like. Process gas is introduced into the reaction chamber 100 through the gas injection port 150 according to process requirements. After stabilization, pump 1901 in actuator 190 draws the metal liquid from reservoir 1902 into cavity 132 of insulating material window 130. The capacitively coupled rf power source 1802 of the source rf power supply 180 inputs rf power into the cavity 132 to capacitively ignite the gases in the reaction chamber 100 to form a plasma. Next, the inductively coupled rf power supply 1801 in the source rf power supply device 180 inputs high frequency rf power to the inductive coil 140. Finally, the pump 1901 in the actuator 190 draws the metal liquid from the cavity 132 of the insulating material window 130 into the reservoir 1902 and stops the rf power feed of the capacitively coupled rf power source 1802 to the cavity 132. At this time, the inductively coupled rf power source 1801 feeds power into the reaction chamber by means of inductive coupling to maintain plasma in the reaction chamber 100. And after the plasma is stabilized, etching the substrate.

Fig. 6 is a flow chart of a method of processing a substrate according to another embodiment of the invention. For example, the substrate is processed by the plasma processing apparatus shown in fig. 2. The substrate 120 is placed on the electrostatic chuck 115. The substrate 120 may be monocrystalline silicon, gallium arsenide, silicon carbide, gallium nitride, zinc oxide, or the like. Process gas is introduced into the reaction chamber 100 through the gas injection port 150 according to process requirements. After stabilization, pump 1901 in actuator 190 draws the metal liquid from reservoir 1902 into cavity 132 of insulating material window 130. The capacitively coupled RF power source 1802 of the source RF power device 180 inputs RF power into the cavity 132, while the inductively coupled RF power source 1801 of the source RF power device 180 inputs RF power into the inductive coil 140 to jointly ignite the gases in the reaction chamber 100 to form a plasma. After ignition of the plasma, pump 1901 in actuator 190 draws the metallic liquid from cavity 132 of insulating material window 130 into reservoir 1902. Next, the rf power feed of the capacitively coupled rf power source 1802 to the cavity 132 is stopped. At this time, the inductively coupled rf power source 1801 feeds power into the reaction chamber by means of inductive coupling to maintain plasma in the reaction chamber 100. And after the plasma is stabilized, etching the substrate.

Fig. 7 is a flow chart of a method of processing a substrate according to yet another embodiment of the invention. For example, a substrate is processed by the plasma processing apparatus shown in fig. 2. The substrate 120 is placed on the electrostatic chuck 115. The substrate 120 may be monocrystalline silicon, gallium arsenide, silicon carbide, gallium nitride, zinc oxide, and the like. Process gas is introduced into the reaction chamber 100 through the gas injection port 150 according to process requirements. After stabilization, pump 1901 in actuator 190 draws the metal liquid from reservoir 1902 into cavity 132 of insulating material window 130. The capacitively coupled rf power source 1802 of the source rf power supply 180 inputs rf power into the cavity 132 to capacitively ignite the gases in the reaction chamber 100 to form a plasma. After ignition of the plasma, the inductively coupled rf power supply 1801 in the source rf power supply device 180 inputs high frequency rf power to the inductive coil 140, and at the same time, the pump 1901 in the actuator 190 draws the metallic liquid from the cavity 132 of the insulating material window 130 into the reservoir 1902. Finally, the rf power feed into cavity 132 by capacitively coupled rf power source 1802 is stopped. At this time, the inductively coupled rf power source 1801 feeds power into the reaction chamber by means of inductive coupling to maintain plasma in the reaction chamber 100. And after the plasma is stabilized, etching the substrate.

When the cavity 132 filled with the metal liquid completely blocks the magnetic field generated by the upper inductor 140, for example, the cavity 132 is configured as shown in fig. 3a, the rf power fed from the capacitively coupled rf power source 1802 to the cavity 132 must be maintained before the metal liquid is completely pumped out to the reservoir 1902, and the inductively coupled rf power source 1801 must input the rf power to the inductor 140 at the latest before the metal liquid is completely pumped out, so as to maintain the plasma in the reaction chamber 100 not to extinguish. When the cavity 132 filled with the metal liquid does not completely shield the magnetic field generated by the upper inductor 140 (i.e., the magnetic field generated by the inductor 140 partially enters the lower reaction chamber 100), for example, the structure of the cavity 132 is as shown in fig. 3b or fig. 3c, after the inductively coupled rf power source 1801 inputs the high-frequency rf power to the inductor 140, the rf power feeding of the capacitively coupled rf power source 1802 to the cavity 132 can be stopped, and the plasma in the reaction chamber 100 is maintained by the inductive coupling.

As described above, by providing a cavity structure in the insulating material window of the inductively coupled plasma processing apparatus and injecting and extracting the metal liquid into and from the cavity by the actuator, it is possible to combine two types of plasma generation methods of capacitive coupling and inductive coupling. The plasma is ignited by means of capacitive coupling, which ignites at low pressure and low power, and then generates a plasma of higher concentration by means of inductive coupling. The combination of the two modes can produce the required plasma state more quickly and efficiently.

Although the present invention has been described with respect to the preferred embodiments, it will be understood by those skilled in the art that the foregoing and various other changes, omissions and deviations in the form and detail thereof may be made without departing from the scope of this invention.

Claims

1. A plasma processing apparatus, comprising:

the device comprises a reaction cavity, a substrate, an insulating material window and an inductance coil, wherein the base is arranged below the reaction cavity, the substrate to be processed is arranged on the base, the top of the reaction cavity comprises the insulating material window, and the inductance coil is arranged above the insulating material window;

a cavity disposed within the insulating material window, the cavity for containing a metal liquid;

the source radio frequency power supply device is used for applying a source radio frequency signal to the induction coil and/or the metal liquid in the cavity;

a bias radio frequency power supply for applying a bias radio frequency signal to the base;

actuating means for withdrawing the molten metal from or injecting the molten metal into the cavity;

and the controller is connected to the source radio frequency power supply device, the bias radio frequency power supply and the actuating device, and is used for controlling the source radio frequency power supply device and the bias radio frequency power supply to input radio frequency power to the reaction cavity and controlling the actuating device to extract or inject metal liquid into the cavity from or into the cavity, wherein the controller is used for controlling the source radio frequency signal to be sequentially or simultaneously applied to the metal liquid and the induction coil in the cavity in the process of processing the substrate.

2. The plasma processing apparatus of claim 1 wherein the source rf power supply means comprises an inductively coupled rf power supply coupled to the inductive coil and a capacitively coupled rf power supply coupled to the metallic liquid within the cavity of the insulating material window.

3. The plasma processing apparatus of claim 1 wherein the source rf power supply means includes a source rf power supply and a power divider for dividing rf power output by the source rf power supply to the inductor coil and the cavity of the insulating material window.

4. A plasma processing apparatus according to claim 2 or 3, characterized in that the magnetic field generated by the induction coil above the insulating material window entirely enters the cavity via the insulating material window.

5. A plasma processing apparatus according to claim 2 or 3, wherein a portion of the magnetic field generated by the inductive coil above the insulating material window enters the cavity via the insulating material window and another portion of the magnetic field enters the reaction chamber via the insulating material window.

6. A plasma treatment device according to claim 1, characterized in that the actuating means comprise a pump and a reservoir, the pump being adapted to at least partly draw the metallic liquid from the reservoir into the cavity or from the cavity into the reservoir.

7. A method of processing a substrate in a plasma processing apparatus, comprising:

introducing a process gas into the reaction chamber;

injecting a metal liquid into a cavity in an insulating material window at the top of the reaction chamber;

feeding radio frequency power into the cavity through a source radio frequency power supply device;

feeding radio frequency power into an inductance coil above the insulating material window through a source radio frequency power supply device;

and pumping the metal liquid into the liquid storage device from the cavity, and stopping the radio frequency power feeding of the source radio frequency power supply device to the cavity.

8. The method of claim 7, comprising:

RF power is simultaneously fed into the inductive coil above the insulating material window and the cavity in the insulating material window by a source RF power supply device to ignite plasma.

9. The method of claim 7, comprising:

radio frequency power is fed into the induction coil above the insulating material window through a source radio frequency power supply device, and meanwhile, the metal liquid is pumped into the liquid storage device from the cavity.

10. The method according to any one of claims 7-9, further comprising: the bias radio frequency power is input to the pedestal through the bias radio frequency power supply.