Plasma source-free radical source free switching cavity and process

Abstract

The invention provides a plasma source-free radical source free switching cavity and process, and the cavity comprises an upper cylinder which is used for generating plasma and free radicals, is provided with a first radio frequency coil and a first air inlet, is provided with an open bottom surface, and is arranged on a lower cover plate; the lower cover plate is arranged at the open end of the lower cylinder body; the plasma filter is arranged on the lower cover plate and is used for filtering plasmas generated in the upper barrel body; and the lower cylinder is used for generating plasma or receiving free radicals, a radio frequency coil II is arranged on the lower cylinder, a base is arranged in the lower cylinder, a wafer is placed on the base, and the top surface of the lower cylinder is opened to form an open end. The free radical mode and the plasma mode can be provided and can be freely switched.

Description

Technical Field

[0001] The present invention belongs to the technical field of plasma source chambers, and in particular relates to a chamber and process for freely switching between a plasma source and a free radical source. Background Art

[0002] In the field of semiconductor manufacturing, such as etching, degumming, surface modification and deposition, plasma is widely used. Inductively coupled plasma sources are widely used due to their high efficiency, high plasma density and low plasma bias. However, in some processes, the plasma potential will cause the plasma to bombard the wafer surface, which will not improve the selectivity, or electrical deviation, or even cause device damage. In this case, free radicals are needed to replace the plasma; free radicals are active particles, without charge, only active energy, and will not cause any plasma damage, electrical deviation or device damage. However, in the process, sometimes a certain amount of plasma energy is needed to bombard the wafer surface, such as plasma is needed in the etching process of SiO2, and only free radicals are needed in the etching process of Si or TiN. This requires a chamber design that can provide both free radical and plasma modes and can switch freely. Summary of the invention

[0003] The purpose of the present invention is to provide a chamber and process for freely switching between plasma source and free radical source, which can provide two modes, free radical and plasma, and can be freely switched. The technical solution adopted is as follows:

[0004] A plasma source-free radical source freely switchable chamber, comprising:

[0005] An upper cylinder, used for generating plasma and free radicals, on which a radio frequency coil and an air inlet are arranged, and whose bottom surface is open and arranged on a lower cover plate; the lower cover plate is arranged on the open end of the lower cylinder;

[0006] A plasma filter, installed on the lower cover plate, for filtering the plasma generated in the upper cylinder;

[0007] The lower cylinder is used to generate plasma or receive free radicals. A second radio frequency coil is arranged on the lower cylinder. A base is arranged inside the lower cylinder. A wafer is placed on the base. The top surface of the base is open to form the open end.

[0008] Preferably, the lower cover plate extends out of the upper cylinder and defines a second air inlet.

[0009] Preferably, the lower surface of the upper cylinder and the upper surface of the lower cover plate are polished, and an O-ring seal is provided in the contact area between the upper cylinder and the lower cover plate.

[0010] Preferably, the lower cover plate is placed on the open end of the lower cylinder, the contact surfaces of the two are polished, and an O-ring seal is provided in the contact area between the lower cylinder and the lower cover plate.

[0011] Preferably, the plasma filter is clamped in a mounting hole on the lower cover plate.

[0012] Preferably, the plasma filter is single-layer or multi-layer.

[0013] Preferably, process gas one introduced into gas inlet one and process gas two introduced into gas inlet two, the two process gases can be selected as a mixture of multiple gases or a single gas according to process requirements, and process gas one and process gas two can be the same or different.

[0014] Preferably, the upper cylinder is a quartz cylinder or a ceramic cylinder; the lower cylinder is a quartz cylinder or a ceramic cylinder; and the lower cover plate is any one of an aluminum alloy plate, a quartz plate, and a ceramic plate.

[0015] Preferably, one terminal of the RF coil is connected to a matcher and a RF power supply in sequence.

[0016] A plasma source-free radical source free switching process, based on the plasma source-free radical source free switching chamber, comprises the following steps:

[0017] Free radical formation mode: process gas 1 enters the upper cylinder from the gas inlet 1, at which time the RF coil 2 does not work, and the RF is coupled into the upper cylinder by the RF coil 1, and the process gas 1 dissociates to form plasma, and the plasma passes through the plasma filter, and the electrons and ions are guided away, and the mixture of free radicals and process gas 1 reaches the upper surface of the wafer to carry out the process;

[0018] Plasma mode formation:

[0019] Process gas 1 enters the upper cylinder from gas inlet 1, at which time the RF power supply corresponding to RF coil 1 may be turned on or off, and the RF power supply corresponding to RF coil 2 is turned on;

[0020] When the RF power supply corresponding to the RF coil 1 is turned on, the RF is coupled into the upper cylinder by the RF coil 1, the gas dissociates to form plasma, the plasma passes through the plasma filter, the electrons and ions are guided away, and the mixture of free radicals and process gas 1 enters the lower cylinder;

[0021] When the RF power supply corresponding to the RF coil 1 is not turned on, the process gas 1 entering through the gas inlet 1 directly passes through the plasma filter and enters the lower cylinder;

[0022] The RF coil 2 applies RF, and the gas inlet 2 can be selected to be gas-intake or gas-free at this time. The RF coupled into the lower cylinder by the RF coil 2 dissociates the gas in the lower cylinder to generate plasma for the process.

[0023] Compared with the prior art, the advantages of the present invention are:

[0024] 1. A design for free switching between free radicals and plasma is provided.

[0025] 2. For some processes, free radical reaction and plasma reaction are two different process nodes. After adopting this design, they can be combined into one, saving process steps and reducing costs. Specifically, it can improve etching performance and reduce wafer processing steps.

[0026] 3. Compared with the design with only one RF coil, the dual RF coil can perform secondary dissociation of the gas, which improves the dissociation efficiency, the plasma or free radical concentration, and the reaction efficiency, such as the etching rate, the degumming rate, and the deposition rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of a chamber structure for freely switching between a plasma source and a free radical source in a free radical mode;

[0028] Figure 2 Schematic diagram of the cavity structure in which the plasma source and free radical source can be switched freely in the plasma mode. DETAILED DESCRIPTION

[0029] The plasma source-radical source free switching chamber and process of the present invention will be described in more detail below in conjunction with the schematic diagram, wherein the preferred embodiment of the present invention is shown, and it should be understood that those skilled in the art can modify the present invention described herein, and still achieve the beneficial effects of the present invention. Therefore, the following description should be understood as being widely known to those skilled in the art, and not as a limitation of the present invention.

[0030] The plasma source has charged ions and electric potential, which are very necessary in some processes that require energy. For example, in the etching of SiO2 or SiN, a certain amount of plasma energy is needed to break the molecular bonds of SiO2 or SiN. However, there are no charged ions in free radicals, which are very suitable for some processes that are very sensitive to plasma damage, or some processes that require extremely high selectivity, which require free radical etching.

[0031] The plasma source-free radical source freely switchable chamber can freely select the plasma source and the free radical source according to the process requirements. The chamber can be used as an etching chamber, a degumming chamber, a surface modification chamber or a deposition chamber.

[0032] like Figures 1-2 , a plasma source-free radical source freely switchable chamber, comprising:

[0033] The upper cylinder is used to generate plasma and free radicals, and is provided with a radio frequency coil and an air inlet. The bottom surface of the upper cylinder is open and is provided on the lower cover plate. The lower cover plate is placed on the open end of the lower cylinder, and the top surface of the upper cylinder is open and is provided with an upper cover plate. The air inlet is provided on the upper cover plate.

[0034] A plasma filter is installed on the lower cover plate and is used to filter the plasma generated in the upper cylinder;

[0035] The lower cylinder is used to generate plasma or receive free radicals. A second radio frequency coil is arranged on the lower cylinder. A base is arranged inside the lower cylinder. A wafer is placed on the base. The top surface of the base is opened to form an open end.

[0036] Furthermore, the lower cover plate extends out of the upper cylinder to form a second air inlet.

[0037] The upper and lower end surfaces of the upper cylinder are polished, and the contact area between the upper cylinder and the lower cover plate, and the contact area between the upper cylinder and the upper cover plate are all provided with O-rings. The connection is completed by gravity, vacuum, and sealing rings.

[0038] The lower cover is placed on the open end of the lower cylinder, the upper and lower contact surfaces of the lower cover are polished, and an O-ring is set in the contact area between the lower cylinder and the lower cover. The connection is completed by gravity, vacuum, and sealing ring.

[0039] The plasma filter is clamped in the mounting hole on the lower cover plate and can be single-layer or multi-layer. The selection is based on process requirements. The pore size and distribution of the filter are designed based on uniformity.

[0040] The upper cylinder is a quartz cylinder or a ceramic cylinder; the lower cylinder is a quartz cylinder or a ceramic cylinder; the lower cover plate is any one of an aluminum alloy plate, a quartz plate, and a ceramic plate;

[0041] One terminal of the RF coil is connected to a matching device and a RF power source in sequence.

[0042] One terminal of the RF coil 2 is connected to a matcher and a RF power source in sequence.

[0043] The two radio frequency coils may be planar structures or three-dimensional structures, one may be a planar structure and the other may be a three-dimensional structure, and the two coils may be single-turn or multi-turn.

[0044] In other embodiments, the RF coil 2 and the RF coil 1 have corresponding matchers and RF power supplies respectively; for a low-cost solution, the RF coil 2 and the RF coil 1 may also share a RF matcher and RF power supply. In this case, the energy is distributed to the two RF coils through proportional distribution of current in the RF matcher. The advantage is low cost, and the disadvantage is that the RF power supply cannot be completely turned off in one coil, and most of it can only be distributed to the other RF coil.

[0045] A plasma source-free radical source free switching process comprises the following steps:

[0046] Free radical mode is formed: process gas 1 enters the upper cylinder from the gas inlet 1. At this time, RF coil 2 is not working (the RF power supply of RF coil 2 is not turned on). RF is coupled into the upper cylinder by RF coil 1. Process gas 1 dissociates to form plasma. The plasma passes through the plasma filter, and electrons and ions are conducted away. A mixture of free radicals and process gas 1 reaches the upper surface of the wafer to carry out the process.

[0047] Plasma mode formation:

[0048] Process gas 1 enters the upper cylinder from gas inlet 1, at which time the RF power supply corresponding to RF coil 1 may be turned on or off, and the RF power supply corresponding to RF coil 2 is turned on;

[0049] When the RF power supply corresponding to the RF coil 1 is turned on, the RF is coupled into the upper cylinder by the RF coil 1, the gas dissociates to form plasma, the plasma passes through the plasma filter, the electrons and ions are guided away, and the mixture of free radicals and process gas 1 enters the lower chamber;

[0050] When the RF power supply corresponding to the RF coil 1 is not turned on, the process gas 1 entering through the gas inlet 1 directly passes through the plasma filter and enters the lower cylinder;

[0051] The RF coil 2 applies RF, and the gas inlet 2 can be selected to be gas-intake or gas-free at this time. The RF coupled into the lower cylinder by the RF coil 2 dissociates the gas in the lower cylinder to generate plasma for the process.

[0052] Switching from the free radical mode to the plasma mode: Based on the free radical mode, the RF coil 2 is started. At this time, the RF coil 1 may or may not have RF energy.

[0053] Switch the plasma mode to the free radical mode: on the basis of the plasma mode, turn off the RF coil 2 (when sharing an RF power supply, adjust the power supply energy of the RF coil 2 to an extremely low level), and turn on the RF coil 1.

[0054] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. A chamber with a plasma source and a free radical source that can be switched freely, characterized in that: include: An upper cylinder, used for generating plasma and free radicals, on which a radio frequency coil and an air inlet are arranged, and whose bottom surface is open and arranged on a lower cover plate; the lower cover plate is arranged on the open end of the lower cylinder; A plasma filter, installed on the lower cover plate, for filtering the plasma generated in the upper cylinder; The lower cylinder is used to generate plasma or receive free radicals. A second radio frequency coil is arranged on the lower cylinder. A base is arranged inside the lower cylinder. A wafer is placed on the base. The top surface of the base is open to form the open end.

2. The plasma source-free radical source freely switchable chamber according to claim 1, characterized in that: The lower cover plate extends out of the upper cylinder and is provided with a second air inlet.

3. The plasma source-free radical source freely switchable chamber according to claim 1, characterized in that: The lower surface of the upper cylinder and the upper surface of the lower cover plate are polished, and an O-ring seal is arranged in the contact area between the upper cylinder and the lower cover plate.

4. The plasma source-free radical source freely switchable chamber according to claim 1, characterized in that: The lower cover plate is placed on the open end of the lower cylinder, the contact surfaces of the two are polished, and an O-ring seal is arranged in the contact area between the lower cylinder and the lower cover plate.

5. The plasma source-free radical source freely switchable chamber according to claim 1, characterized in that: The plasma filter is clamped in the mounting hole on the lower cover plate.

6. The plasma source-free radical source freely switchable chamber according to claim 1, characterized in that: The plasma filter is single-layer or multi-layer.

7. The plasma source-free radical source freely switchable chamber according to claim 1, characterized in that: Process gas one introduced into gas inlet one and process gas two introduced into gas inlet two, the two process gases can be selected as a mixture of multiple gases or a single gas according to process requirements, and process gas one and process gas two can be the same or different.

8. The plasma source-free radical source freely switchable chamber according to claim 1, characterized in that: The upper cylinder is a quartz cylinder or a ceramic cylinder; the lower cylinder is a quartz cylinder or a ceramic cylinder; the lower cover plate is any one of an aluminum alloy plate, a quartz plate, and a ceramic plate.

9. The plasma source-free radical source freely switchable chamber according to claim 1, characterized in that: One terminal of the RF coil is connected to a matcher and a RF power source in sequence.

10. A plasma source-free radical source free switching process, based on the plasma source-free radical source free switching chamber according to any one of claims 1 to 9, characterized in that: The following steps are involved: Free radical formation mode: process gas 1 enters the upper cylinder from the gas inlet 1, at which time the RF coil 2 does not work, and the RF is coupled into the upper cylinder by the RF coil 1, and the process gas 1 dissociates to form plasma, and the plasma passes through the plasma filter, and the electrons and ions are guided away, and the mixture of free radicals and process gas 1 reaches the upper surface of the wafer to carry out the process; Plasma mode formation: Process gas 1 enters the upper cylinder from gas inlet 1, at which time the RF power supply corresponding to RF coil 1 may be turned on or off, and the RF power supply corresponding to RF coil 2 is turned on; When the RF power supply corresponding to the RF coil 1 is turned on, the RF is coupled into the upper cylinder by the RF coil 1, the gas dissociates to form plasma, the plasma passes through the plasma filter, the electrons and ions are guided away, and the mixture of free radicals and process gas 1 enters the lower cylinder; When the RF power supply corresponding to the RF coil 1 is not turned on, the process gas 1 entering through the gas inlet 1 directly passes through the plasma filter and enters the lower cylinder; The RF coil 2 applies RF, and the gas inlet 2 can be selected to be gas-intake or gas-free at this time. The RF coupled into the lower cylinder by the RF coil 2 dissociates the gas in the lower cylinder to generate plasma for the process.

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