Plasma treatment method and apparatus

Abstract

The plasma processing apparatus of the embodiment includes a plasma source, a nozzle in a plasma chamber, the nozzle capable of guiding plasma from the plasma source to a wafer to be processed, the plasma having the form of a plasma stream at the nozzle outlet, an outer annular portion disposed on the wafer in the plasma chamber and surrounding the nozzle, a gas exhaust port disposed between the inner side wall of the outer annular portion and the outer side wall of the nozzle, and a first vacuum pump connected to the gas exhaust port between the inner side wall of the outer annular portion and the outer side wall of the nozzle.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims priority and the benefit of the filing date of U.S. Patent Application No. 18 / 328,345, filed on June 2, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention generally relates to plasma processing, and in specific embodiments, relates to plasma processing methods and apparatuses.

Background Art

[0003] Semiconductor manufacturing processes can involve various manufacturing techniques including the formation, patterning, and removal of multiple layers on a substrate. In various steps of semiconductor manufacturing processes, plasma processes are commonly used. For example, reactive ion etching (RIE), plasma - enhanced CVD (PECVD), and plasma - enhanced atomic layer deposition (PEALD) are common process steps in the manufacture of semiconductor devices.

[0004] Semiconductor wafer die manufacturing processes can also include various processes used for wafer thinning and planarization. Chemical mechanical planarization (CMP) is a process that can be used to thin and planarize the entire wafer, but it has limited ability to controllably thin local regions of the wafer.

[0005] Local or partial plasma etching can be used to remove materials within specific regions of a wafer using plasma while leaving materials in other surrounding regions of the wafer. As plasma processes in the semiconductor industry further advance, there is a need to improve existing plasma etching processes. These improvements are necessary to reduce etching damage to the surrounding regions of the wafer from uncontrolled plasma flow during local or partial plasma etching. Improvements are also needed to enable better control of etching across the entire surface of the wafer, resulting in improved uniformity across the entire wafer. [Overview of the Initiative]

[0006] According to one embodiment, the plasma processing apparatus comprises a plasma source, a nozzle in a plasma chamber, the nozzle capable of guiding plasma from the plasma source to a wafer to be processed, the plasma having the form of a plasma stream at the nozzle outlet, an outer annular portion disposed on the wafer in the plasma chamber and surrounding the nozzle, a gas exhaust port disposed between the inner side wall of the outer annular portion and the outer side wall of the nozzle, and a first vacuum pump connected to the gas exhaust port between the inner side wall of the outer annular portion and the outer side wall of the nozzle.

[0007] According to one embodiment, a plasma processing method includes generating plasma from a plasma source, and guiding the plasma into a processing chamber and onto the outer surface of a wafer using a nozzle, wherein the plasma exits from the end of a nozzle positioned above the outer surface of the wafer, and the plasma exits in the form of a plasma stream, the nozzle extends through a gas shroud surrounding the nozzle and positioned on the wafer, and a gas exhaust port is positioned between the inner side wall of the gas shroud and the outer side wall of the nozzle, and maintaining a first pressure at the gas exhaust port using a first vacuum pump, and maintaining a second pressure in the processing chamber using a second vacuum pump, wherein the first pressure and the second pressure are different.

[0008] According to one embodiment, the apparatus comprises a plasma source; a gas shroud having a concave shape with a flat central portion and positioned on a wafer to be processed within a processing chamber; a nozzle extending through a first opening in the flat central portion and configured to deliver plasma from the plasma source to the outer surface of the wafer; and a plurality of exhaust outlets extending from a second opening in the flat central portion and arranged radially around the nozzle.

[0009] The above has provided a fairly broad overview of the features and technical advantages of the Disclosure so that the detailed description of the Disclosure below may be better understood. This specification describes additional features and advantages of the Disclosure that form the subject matter of the claims of the Disclosure. It should be understood by those skilled in the art that the concepts and particular embodiments disclosed can be readily used as a basis for modifying or designing other structures or processes to accomplish the same objectives of the Disclosure. It should also be recognized by those skilled in the art that such equivalent structures do not deviate from the spirit and scope of the Disclosure as set forth in the appended claims. [Brief explanation of the drawing]

[0010] For a more complete understanding of this disclosure and its advantages, the following description should be referred to in conjunction with the attached drawings.

[0011] [Figure 1] Block diagrams of plasma processing systems according to various embodiments of this disclosure are shown. [Figure 2] Figure 1 shows cross-sectional views of a region of a plasma processing system according to various embodiments of the present disclosure. [Figure 3] A block diagram of a plasma processing system according to an embodiment of the present disclosure is shown. [Figure 4] Figure 3 shows a cross-sectional view of a region of the plasma processing system according to an embodiment of the present disclosure. [Figure 5] A block diagram of a plasma processing system according to an embodiment of the present disclosure is shown. [Figure 6A] Figure 5 shows a perspective view of the gas shroud of the plasma processing system according to an embodiment of the present disclosure. [Figure 6B] Figure 5 shows a perspective view of the region of the plasma processing system according to an embodiment of the present disclosure. [Figure 7] Figure 5 shows a symmetrical cross-sectional view representing one-eighth of the hollow space of the plasma processing system shown in the present disclosure, according to an alternative embodiment of the present disclosure. [Figure 8]A symmetrical cross-sectional view representing one-eighth of the hollow space of a plasma processing system according to an alternative embodiment of the present disclosure is shown. [Figure 9A] Exemplary temperature-versus-distance traces along the top surface of a wafer during different etching processes are shown according to alternative embodiments of the present disclosure. [Figure 9B] Exemplary traces of pressure versus distance along the upper surface of a wafer during different etching processes are shown according to alternative embodiments of the present disclosure.

[0012] Corresponding numbers and symbols in different drawings generally refer to corresponding parts unless otherwise indicated. The drawings are drawn to clearly illustrate relevant aspects of various embodiments and are not necessarily drawn to scale. [Modes for carrying out the invention]

[0013] The preparation and use of current preferred embodiments will be discussed in detail below. However, it should be understood that this disclosure provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific methods for preparing and using this disclosure and do not limit the scope of this disclosure.

[0014] This disclosure describes preferred embodiments in a specific context, namely, apparatus and methods for local or partial plasma etching, including a nozzle that guides plasma and reactive species (e.g., ions, electrons, radicals, etc.) from a plasma source to a wafer to be etched. The plasma is guided in the form of a plasma stream at the nozzle exit. The wafer to be etched and the nozzle exit may be within a plasma chamber. The apparatus and methods may include a gas annular portion fitted around the nozzle. In alternative embodiments, the apparatus and methods may include a gas shroud instead of a gas annular portion, and the nozzle is fitted within and surrounded by the gas shroud. When the inlet pressure at the nozzle, the outlet pressure at the gas annular portion (or gas shroud), and the chamber pressure in the plasma chamber are properly calibrated, the gas annular portion (or gas shroud) functions as an outlet or vent (e.g., exhaust port) through which unreacted plasma, gas, and by-products generated during the plasma processing of the wafer are removed from the plasma chamber.

[0015] Benefits can be realized by appropriately calibrating the inlet pressure at the nozzle, the outlet pressure at the gas annular section (or gas shroud), and the chamber pressure at the plasma chamber, so that the gas annular section (or gas shroud) functions as an outlet or vent (e.g., an exhaust port) for unreacted plasma to exit the plasma chamber. This includes the ability to control the plasma flow after it strikes the wafer, so that the unreacted plasma interacts only with a reduced area (e.g., a first region) on the upper surface of the wafer. This thus enables high-resolution etching, better uniformity across the entire wafer surface, and reduced etching damage from unreacted plasma to surrounding areas of the wafer (e.g., other areas surrounding the first region) during partial plasma etching. Various embodiments are described in detail below with reference to the accompanying drawings.

[0016] Figure 1 shows a schematic cross-sectional view of an example of a plasma processing system 100 according to the technology described herein. Depending on the implementation, the plasma processing system 100 may be a capacitively coupled plasma (CCP) processing system, an inductively coupled plasma (ICP) processing system, a microwave-generated plasma system, etc. The plasma processing system 100 will be described later for use in connection with etching operations. However, aspects of the embodiments described herein may be used for other plasma operations, including ashing, deposition, cleaning, plasma polymerization, plasma-enhanced chemical vapor deposition (PECVD), plasma atomic layer deposition (PEALD), etc. The plasma processing can be performed in a plasma processing chamber 114, which may be a vacuum chamber made of a metal such as aluminum or stainless steel.

[0017] The plasma processing system 100 may use a high-voltage, high-frequency (RF) power supply to assist in plasma generation. The RF power supply may be a high-frequency (HF) power supply, a microwave source, etc. Figure 1 shows a microwave generator 104 that generates electromagnetic waves (microwaves) distributed to the plasma source 106 from which the plasma is generated. The plasma source 106 is located above the plasma processing chamber 114 and may comprise a plasma cavity and plasma elements (e.g., one or more electrodes) used to generate and maintain plasma within the plasma cavity. In one embodiment, the plasma source 106 may be a remote plasma source located at a different location, and the plasma, after being generated, is guided to the surface to be etched. The plasma elements can generate plasma, which then flows into the plasma processing chamber 114 through a nozzle 108. Thus, the plasma is generated outside the plasma processing chamber 114 and then introduced into the plasma processing chamber using a gas flow.

[0018] A process gas is introduced into the plasma cavity of the plasma source 106, where it is ionized and excited by the plasma. Depending on the specific process being performed, this gas may be a mixture of one or more reactive gases such as oxygen, nitrogen, hydrogen, and fluorine. The process gas is supplied using the process gas supply unit 118 and introduced into the plasma cavity through the gas inlet. The process gas may be mixed with a carrier gas such as argon or helium to ensure uniform distribution and stable plasma operation. The gas mixture is then excited by the plasma, which dissociates the gas molecules into reactive species such as radicals, ions, or excited molecules.

[0019] Next, the plasma and reactive species generated by the plasma source 106 flow into the plasma processing chamber 114 through the nozzle 108, and the outlet of the nozzle 108 is positioned above the wafer support 117 (e.g., a wafer vacuum chuck, etc.) within the plasma processing chamber 114. The wafer support 117 is configured to hold the wafer 126 (or, e.g., a substrate, etc.) to be etched such that the reactive species and plasma are discharged from the outlet of the nozzle 108 toward the upper surface of the wafer 126. In one embodiment, the wafer support 117 is capable of rotating the wafer 126 while the etching process is being performed on the wafer 126. The plasma and reactive species are directed toward the upper surface of the wafer 126 in the form of a plasma stream 112 at the outlet of the nozzle 108. The plasma stream 112 includes a narrow column or stream of plasma and reactive species. (Hereinafter, it may also be referred to as the inner annular portion) The nozzle 108 comprises a tube or pipe having an annular cross-section. For example, the nozzle 108 may comprise a hollow cylindrical structure having a central open space or hole and a circular cross-section, resulting in an annular cross-section. The nozzle 108 may have an outer diameter D1 between the outermost sidewalls of the nozzle 108. The nozzle 108 may have an inner diameter D2 (subsequently shown in FIG. 2) between the innermost sidewalls of the nozzle 108. In one embodiment, the inner diameter D2 of the nozzle 108 is constant throughout the length of the nozzle 108. In one embodiment, the nozzle 108 may comprise a material that is non-reactive or inert with respect to the plasma delivered by the nozzle 108 toward the upper surface of the wafer 126. For example, the nozzle 108 may comprise sapphire, tungsten, or a ceramic (e.g., silicon carbide, alumina, yttria, etc.).

[0020] The plasma processing system 100 may also include an outer annular portion 110. The outer annular portion 110 comprises a tube or pipe having an annular cross-section. For example, the outer annular portion 110 may comprise a hollow cylindrical structure having a central open space or hole and a circular cross-section, resulting in a ring-shaped cross-section. The nozzle 108 is disposed inside the outer annular portion 110 such that the outer annular portion surrounds the nozzle 108. The outer annular portion 110 may have an outer diameter D3 between the outermost sidewalls of the outer annular portion 110, and the outer diameter D3 is larger than the outer diameter D1. The outer annular portion 110 may have an inner diameter D4 (subsequently shown in FIG. 2) between the innermost sidewalls of the outer annular portion 110, and the inner diameter D4 is larger than the outer diameter D1. The nozzle 108 is disposed inside the outer annular portion 110 such that a gas exhaust port 109 is formed between the inner sidewall of the outer annular portion 110 and the outer sidewall of the nozzle 108. The gas exhaust port 109 comprises a space or gap between the inner sidewall of the outer annular portion 110 and the outer sidewall of the nozzle 108. The gas exhaust port 109 surrounds the peripheral portion of the outer sidewall of the nozzle 108. In one embodiment, unreacted plasma (and reactive species), as well as gases and by-products generated during the plasma processing of the wafer 126, are removed from the plasma processing chamber 114 through the gas exhaust port 109. In one embodiment, the outer annular portion 110 may comprise materials such as stainless steel, ceramics (e.g., alumina, silicon carbide, yttria).

[0021] The vacuum pump 120 is connected to the gas exhaust port 109 between the outer annular portion 110 and the nozzle 108 and is used to discharge unreacted plasma (and reactive species) and gases and by-products generated during the plasma processing of the wafer 126 out of the plasma processing chamber 114 through the gas exhaust port 109 and through the gas outlet. Accordingly, the gas exhaust port 109 between the inner sidewall of the outer annular portion 110 and the outer sidewall of the nozzle 108 is an outlet or exhaust port through which unreacted plasma (and reactive species) and gases and by-products generated during the plasma processing of the wafer are removed from the plasma processing chamber 114.

[0022] During the etching process using the plasma processing system 100, the wafer 126 can be moved or scanned under the plasma stream 112 to etch material from the wafer 126. The wafer scanning speed and residence time during the etching process can be controlled to control uniformity across the entire wafer 126 and enable uniform etching across the entire surface of the wafer 126.

[0023] The vacuum pump 122 is connected to the plasma processing chamber 114 through a gas outlet, and the vacuum pump 122 helps maintain a desired pressure in region 115 of the plasma processing chamber 114.

[0024] Figure 2 shows a cross-sectional view of region 124 of the plasma processing system 100 previously shown in Figure 1. The outer annular portion 110 and nozzle 108 are shown as being positioned on the wafer 126. Specifically, the nozzle 108 and outer annular portion 110 are positioned on the area of ​​the wafer 126 to be etched. The outer annular portion 110 may include materials such as stainless steel, ceramics (e.g., alumina, silicon carbide, yttria), etc. The nozzle 108 may include materials such as sapphire, tungsten, ceramics (e.g., silicon carbide, alumina, yttria), etc. Although the outer annular portion 110 and nozzle 108 are described as being used in connection with an etching process, it should be noted that the embodiments described herein (including the outer annular portion 110 and nozzle 108) may be used in connection with other types of plasma operations. These operations include ashing, deposition, cleaning, plasma polymerization, plasma-enhanced chemical vapor deposition (PECVD), plasma atomic layer deposition (PEALD), etc.

[0025] As shown in various embodiments, the nozzle 108 (which may hereafter also be called the inner annular section) comprises a tube or pipe having an annular cross-section. For example, the nozzle 108 may comprise a hollow cylindrical structure having an open space or hole in the center and a circular cross-section, resulting in a ring-shaped cross-section. The nozzle 108 may have an outer diameter D1 between its outermost side walls. The nozzle 108 may have an inner diameter D2 between its innermost side walls. In one embodiment, the outer diameter D1 is in the range of 6 mm to 25 mm, and the inner diameter D2 is in the range of 5 mm to 20 mm. The outer annular section 110 comprises a tube or pipe having an annular cross-section. For example, the outer annular section 110 may comprise a hollow cylindrical structure having an open space or hole in the center and a circular cross-section, resulting in a ring-shaped cross-section. The nozzle 108 is positioned inside the outer annular section 110 such that the outer annular section surrounds the nozzle 108. The axis (hereinafter also referred to as the length) of the nozzle 108 is positioned perpendicular to the inside of the outer annular portion 110. The outer annular portion 110 may have an outer diameter D3 between its outermost side walls, and the outer diameter D3 is greater than the outer diameter D1. The outer annular portion 110 may have an inner diameter D4 between its innermost side walls, and the inner diameter D4 is greater than the outer diameter D1. In one embodiment, the outer diameter D3 may be in the range of 8 mm to 40 mm, and the inner diameter D4 may be in the range of 7 mm to 30 mm.

[0026] The outer annular portion 110 may be positioned such that its lowest surface is below the lowest surface (e.g., the outlet) of the nozzle 108. In this way, the lowest surface of the outer annular portion 110 is closer to the top surface of the wafer 126 than the lowest surface of the nozzle 108, and the bottom of the side wall of the outer annular portion 110 may be below the side wall of the nozzle 108. For example, the lowest surface (e.g., the outlet) of the nozzle 108 may be above the top surface of the wafer 126 by a height H1 in the range of 0.5 mm to 20 mm. The lowest surface of the outer annular portion 110 may be above the top surface of the wafer 126 by a height H2 in the range of 0.5 mm to 20 mm. In an alternative embodiment, heights H1 and H2 are equal. The nozzle 108 is positioned inside the outer annular portion 110 such that a gas exhaust port 109 is formed between the inner side wall of the outer annular portion 110 and the outer side wall of the nozzle 108. The gas exhaust port 109 surrounds the peripheral area of ​​the outer side wall of the nozzle 108.

[0027] Plasma and reactive species flowing from the plasma source 106 into the plasma processing chamber 114 travel through the nozzle 108. The outlet of the nozzle 108 is positioned a height H1 above the top surface of the wafer 126. In one embodiment, the pressure P1 at the nozzle 108 (hereinafter also called the plasma inlet) can be in the range of 1 Torr to 20 Tor. The pressure P1 depends on both the plasma flow rate and the gas flow rate through the nozzle 108. A vacuum pump 120 is connected to a gas exhaust port 109 between the outer annular portion 110 and the nozzle 108 and is used to maintain the pressure P2 at the gas exhaust port 109. In one embodiment, the pressure P2 at the gas exhaust port 109 can be in the range of 0 Torr to 2 Tor. A vacuum pump 122 is connected to the plasma processing chamber 114 through a gas outlet and helps maintain the pressure P3 in region 115 (shown earlier in Figure 1) of the plasma processing chamber 114. Pressure P3, sometimes referred to as chamber pressure from now on, can range from 1 Torr to 100 Torr.

[0028] In various embodiments, the ratio of pressure P3 to pressure P2 can vary within the range of 2:1 to 100:1, for example, 10:1 to 20:1 in one embodiment. The relative pressure difference between pressure P2 and pressure P3 causes the plasma and byproduct flow 119 to move relatively vertically upward, ensuring that it is reliably discharged from the plasma processing chamber 114 through the gas exhaust port 109.

[0029] During the etching process for etching material from wafer 126, plasma and reactive species are ejected from the outlet of nozzle 108 toward the upper surface of wafer 126 in the form of a plasma stream 112 (as described above in Figure 1). The plasma stream 112 moves away from the outlet of nozzle 108 (for example, vertically downward) until it encounters the upper surface of wafer 126 to be etched. Unreacted plasma (and reactive species), as well as gases and by-products generated from the etching process of wafer 126, may tend to move in the form of a flow 119 into region 115 of the plasma processing chamber 114.

[0030] Vacuum pump 120 is used to maintain pressure P2 at gas exhaust port 109, and vacuum pump 122 is used to maintain pressure P3 in region 115 (shown earlier in Figure 1) of the plasma processing chamber 114. Pressure P1 at nozzle 108 is maintained by appropriately setting the flow rates of plasma and gas through nozzle 108. Pressure P2 at gas exhaust port 109 is maintained lower than pressure P3 in region 115 (shown earlier in Figure 1) of the plasma processing chamber 114.

[0031] In various embodiments, advantages can be realized when the ratio of pressure P3 to pressure P2 varies in the range of 2:1 to 100:1, for example, in one embodiment, in the range of 10:1 to 20:1. These advantages include the ability to control the plasma flow immediately after impact with the wafer 126, and the immediate removal of all unreacted plasma (and reactive species) from the plasma processing chamber 114 through the gas exhaust port 109 adjacent to the nozzle 108. This ensures that the unreacted plasma (and reactive species) interacts only with a reduced area (e.g., a first region) on the upper surface of the wafer 126 before being removed from the plasma processing chamber 114. Thus, this enables high-resolution etching, better uniformity across the entire surface of the wafer 126, and reduced etching damage from unreacted plasma (and reactive species) to surrounding areas of the wafer 126 (e.g., other areas surrounding the first region) during the etching process.

[0032] In one embodiment in which the outer annular portion 110 has an outer diameter D3 and an inner diameter D4 as described above, if the pressure P2 at the gas exhaust port 109 is kept lower than the pressure P3 in region 115 of the plasma processing chamber 114 (shown earlier in Figure 1), and the difference between pressure P3 and pressure P2 is kept within the range of 50 Torr to 100 Torr, the entire flow 119 moves vertically upward and is discharged from the plasma processing chamber 114 through the gas exhaust port 109. The flow 119 includes unreacted plasma (and reactive species), as well as gases and by-products generated from the etching process of the wafer 126. In addition, there is also a gas flow (flow 121) that exits the plasma processing chamber 114 from region 115 of the plasma processing chamber 114 through the gas exhaust port 109. Therefore, if the pressure P1 at nozzle 108, the pressure P2 at gas exhaust port 109, and the pressure P3 in region 115 of plasma processing chamber 114 are properly calibrated, gas exhaust port 109 functions as an adjacent exhaust port through which all unreacted plasma (and reactive species), as well as gases and by-products generated during the etching process of wafer 126, are removed from plasma processing chamber 114. The unreacted plasma (and reactive species), as well as gases and by-products generated during the etching process of wafer 126, are removed in the form of flow 119.

[0033] The advantages can be achieved by performing an etching process on the wafer 126 using a plasma processing system 100 comprising an outer annular portion and a nozzle 108, the nozzle 108 being located inside the outer annular portion 110 and surrounded by the outer annular portion 110. In addition, the plasma processing system 100 is used to maintain the pressure P1 at the nozzle 108, the pressure P2 at the gas exhaust port 109, and the pressure P3 at the region 115 of the plasma processing chamber 114 during the etching process, such that the pressure P2 at the gas exhaust port 109 is lower than the pressure P3 at the region 115 of the plasma processing chamber 114, and the difference between pressure P3 and pressure P2 is maintained within the range of 50 Torre to 100 Torre. These advantages include the ability to control the plasma flow immediately after impact with the wafer 126, and the immediate removal of all unreacted plasma (and reactive species) from the plasma processing chamber 114 through the gas exhaust port 109 adjacent to the nozzle 108. This ensures that unreacted plasma (and reactive species) interacts only with a reduced area (e.g., the first region) on the upper surface of the wafer 126 before being removed from the plasma processing chamber 114. This thus enables high-resolution etching, better uniformity across the entire surface of the wafer 126, and reduced etching damage from unreacted plasma (and reactive species) to surrounding areas of the wafer 126 (e.g., other areas surrounding the first region) during the etching process. If the pressure P2 at the gas exhaust port 109 is lower than the pressure P3 in region 115 of the plasma processing chamber 114, and the difference between pressure P3 and pressure P2 is less than 50 Torre, the flow 119 (including, for example, unreacted plasma (and reactive species)) will flow into region 115 of the plasma processing chamber 114 in addition to moving into the gas exhaust port 109. As a result, surrounding regions of the wafer 126 (for example, other regions surrounding the first region) are exposed to the flow 119, and consequently, etching damage is caused to these surrounding regions by unreacted plasma (and reactive species).If the pressure P2 at the gas exhaust port 109 is lower than the pressure P3 in region 115 of the plasma processing chamber 114, and the difference between pressure P3 and pressure P2 is greater than 100 Torre, the plasma flowing through the nozzle 108 cannot flow effectively from the nozzle 108, negatively affecting the formation of the plasma stream 112. This results in a decrease in the etching performance of the etching process on the wafer 126.

[0034] Further advantages can be realized by performing an etching process on a wafer 126 using a plasma processing system 100 comprising the outer annular portion 110 and nozzle 108 as described above, wherein the lowest surface of the nozzle 108 (e.g., the exit) is above the upper surface of the wafer 126 by a height H1 in the range of 0.5 mm to 20 mm, and the lowest surface of the outer annular portion 110 is above the upper surface of the wafer 126 by a height H2 in the range of 0.5 mm to 20 mm. In this way, the bottom of the side wall of the outer annular portion 110 is below the side wall of the nozzle 108. These advantages include assisting and guiding all unreacted plasma (and reactive species), as well as gases and by-products generated during the etching process of the wafer 126, into the gas exhaust port 109 to remove them from the plasma processing chamber 114.

[0035] Figure 3 shows a schematic cross-sectional view of the plasma treatment system 100 according to an alternative embodiment. The plasma treatment system 100 in Figure 3 includes the features described in Figures 1 and 2, as well as additional features that provide further advantages. Unless otherwise specified, similar reference numerals discussed in this embodiment (and embodiments discussed hereafter) represent similar components formed by similar processes described and illustrated in Figures 1 and 2. Accordingly, process steps and applicable materials may not be repeated herein.

[0036] The plasma processing system 100 shown in Figure 3 may differ from the plasma processing systems shown in Figures 1 and 2 in that the plasma processing system 100 does not include the outer annular portion 110 described in Figures 1 and 2. Instead, the plasma processing system 100 of Figure 3 includes a gas shroud 130 (which may hereafter also be called the outer annular portion).

[0037] As previously described in Figures 1 and 2, the plasma and reactive species generated in the plasma source 106 flow into the plasma processing chamber 114 through the nozzle 108. The outlet of the nozzle 108 is positioned on a wafer support 117 (e.g., a wafer vacuum chuck) in the plasma processing chamber 114. The wafer support 117 is configured to hold the wafer 126 (or, for example, a substrate) to be etched so that the reactive species and plasma are ejected from the outlet of the nozzle 108 toward the upper surface of the wafer 126. In one embodiment, the wafer support 117 can rotate the wafer 126 while the etching process is being performed on the wafer 126. The plasma and reactive species are guided toward the upper surface of the wafer 126 in the form of a plasma stream 112 at the outlet of the nozzle 108, in the manner previously described in Figures 1 and 2. The nozzle 108 (which may hereafter be called the inner annular section) comprises a tube or pipe having an annular cross-section. For example, the nozzle 108 may have a hollow cylindrical structure having an open space or hole in the center and a circular cross-section, resulting in a ring-shaped cross-section. The nozzle 108 may have an outer diameter D5 (later shown in Figure 4) between its outermost side walls. The nozzle 108 may have an inner diameter D6 (later shown in Figure 4) between its innermost side walls. In one embodiment, the nozzle 108 may include a material that is non-reactive or inert to the plasma that the nozzle 108 delivers toward the upper surface of the wafer 126. For example, the nozzle 108 may include sapphire, tungsten, or ceramic (e.g., silicon carbide, alumina, yttria, etc.).

[0038] The plasma processing system 100 may also include a gas shroud 130 (which may hereafter also be called an outer annular section). The gas shroud 130 may comprise a tube or pipe having an annular cross-section. For example, the gas shroud 130 may comprise a hollow cylindrical structure having an open space or hole in the center and a circular cross-section, resulting in a ring-shaped cross-section. The nozzle 108 is positioned perpendicularly inside the gas shroud 130 such that the gas shroud 130 surrounds the nozzle 108. The gas shroud 130 may have different cross-sectional diameters such that the outer diameter between the outermost side walls of the gas shroud 130 can vary perpendicularly along the axis (hereafter also called the length) of the gas shroud 130. For example, a gas shroud 130 may comprise a first portion 130a, a second portion 130b, and a third portion 130c, wherein the first portion 130a has a constant first outer diameter (e.g., outer diameter D8 shown subsequently in Figure 4), and the third portion 130c has a constant second outer diameter (e.g., outer diameter D10 shown subsequently in Figure 4), the second outer diameter being greater than the first outer diameter. The second portion 130b is positioned between the first portion 130a and the third portion 130c, connecting them, such that the second portion 130b has a third outer diameter that varies along the axis (hereinafter also called the length) of the second portion 130b. The third outer diameter has a value that ranges from a value equal to the first outer diameter at one end of the second portion 130b of the gas shroud to a value equal to the second outer diameter at the second end of the second portion 130b of the gas shroud.

[0039] The first and second outer diameters of the second portion of the gas shroud 130 are larger than the outer diameter D5 of the nozzle 108. The nozzle 108 is positioned inside the gas shroud 130 such that a gas exhaust port 109 is formed between the inner side wall of the gas shroud 130 and the outer side wall of the nozzle 108. The gas exhaust port 109 has a space or gap between the inner side wall of the gas shroud 130 and the outer side wall of the nozzle 108. The gas exhaust port 109 surrounds the periphery of the outer side wall of the nozzle 108. In one embodiment, unreacted plasma (and reactive species), as well as gases and by-products generated during the plasma processing of the wafer 126, are removed from the plasma processing chamber 114 through the gas exhaust port 109. In one embodiment, the gas shroud 130 may include a material such as stainless steel. In other embodiments, the gas shroud 130 may include a chemical-resistant high-temperature alloy.

[0040] The vacuum pump 120 is connected to the gas exhaust port 109 of the gas shroud 130 and is used to expel unreacted plasma (and reactive species) as well as gases and by-products generated during the plasma processing of the wafer 126 from the plasma processing chamber 114 through the gas exhaust port 109 and one or more gas outlets. Therefore, the gas exhaust port 109 between the inner side wall of the gas shroud 130 and the outer side wall of the nozzle 108 is an outlet or exhaust port from which unreacted plasma (and reactive species) as well as gases and by-products generated during the plasma processing of the wafer are removed from the plasma processing chamber 114.

[0041] Figure 4 shows a cross-sectional view of region 132 of the plasma processing system 100 previously shown in Figure 3. The gas shroud 130 and nozzle 108 are shown as being positioned on the wafer 126 within the plasma processing chamber 114. Specifically, the nozzle 108 and gas shroud 130 are positioned on the area of ​​the wafer 126 to be etched. The gas shroud 130 may include a material such as stainless steel. In other embodiments, the gas shroud 130 may include a chemical-resistant high-temperature alloy. The nozzle 108 may include a material such as sapphire, tungsten, or ceramic (e.g., silicon carbide, alumina, yttria, etc.). Although the gas shroud 130 and nozzle 108 are described as being used in connection with an etching process, it should be noted that the embodiments described herein (including the gas shroud 130 and nozzle 108) may be used in connection with other types of plasma operations. These operations include ashing, deposition, cleaning, plasma polymerization, plasma-enhanced chemical vapor deposition (PECVD), and plasma atomic layer deposition (PEALD).

[0042] As shown in various embodiments, the nozzle 108 (which may hereafter also be called the inner annular section) comprises a tube or pipe having an annular cross-section. For example, the nozzle 108 may comprise a hollow cylindrical structure having an open space or hole in the center and a circular cross-section, resulting in a ring-shaped cross-section. The nozzle 108 may have an outer diameter D5 between its outermost side walls. The nozzle 108 may have an inner diameter D6 between its innermost side walls. In one embodiment, the outer diameter D5 is in the range of 6 mm to 25 mm, and the inner diameter D6 is in the range of 5 mm to 20 mm.

[0043] The gas shroud 130 (which may hereafter also be called the outer annular section) may comprise a tube or pipe having an annular cross-section. For example, the gas shroud 130 may comprise a hollow cylindrical structure having an open space or hole in the center and a circular cross-section, resulting in a ring-shaped cross-section. The nozzle 108 is positioned perpendicularly inside the gas shroud 130 such that the gas shroud 130 surrounds the nozzle 108. The gas shroud 130 may have different cross-sectional diameters such that the outer diameter between the outermost side walls of the gas shroud 130 may vary perpendicularly along the axis (hereafter also called the length) of the gas shroud 130. For example, the gas shroud 130 may comprise a first portion 130a, a second portion 130b, and a third portion 130c, where the first portion 130a may have an inner diameter D7 between its innermost side walls and an outer diameter D8 between its outermost side walls. The inner diameter D7 and outer diameter D8 may be constant along the axis (hereinafter also called the length) of the first portion 130a. The third portion 130c may have an inner diameter D9 between its innermost side walls and an outer diameter D10 between its outermost side walls. The inner diameter D9 and outer diameter D10 may be constant along the axis (hereinafter also called the length) of the third portion 130c of the gas shroud. The second portion 130b of the gas shroud is positioned between the first portion 130a and the third portion 130c of the gas shroud, connecting the first portion 130a and the third portion 130c of the gas shroud, such that the second portion 130b of the gas shroud has an outer diameter and inner diameter that vary along the axis (hereinafter also called the length) of the second portion 130b of the gas shroud. The outer diameter of the second portion 130b of the gas shroud varies from a value equal to the outer diameter D8 at the first end of the second portion 130b of the gas shroud to a value equal to the outer diameter D10 at the second end of the second portion 130b of the gas shroud.The inner diameter of the second portion 130b of the gas shroud has a value that ranges from equal to the inner diameter D7 at the first end of the second portion 130b of the gas shroud to equal to the inner diameter D9 at the second end of the second portion 130b of the gas shroud.

[0044] In one embodiment, the inner diameter D7 may be in the range of 20 mm to 60 mm, the outer diameter D8 may be in the range of 21 mm to 65 mm, the inner diameter D9 may be in the range of 40 mm to 100 mm, and the outer diameter D10 may be in the range of 41 mm to 110 mm. In one embodiment, the first portion 130a of the gas shroud is closer to the wafer 126 than the second portion 130b and the third portion 130c of the gas shroud. In one embodiment, the inner diameters D7, D8, D9, and D10 are larger than the outer diameters D5 and D6. In one embodiment, the outer diameter D10 is larger than the outer diameter D8, and the inner diameter D9 is larger than the inner diameter D7.

[0045] In one embodiment, the gas shroud 130 may also include a sleeve 133, which may be a tube or pipe having an annular cross-section. For example, the sleeve 133 may be a hollow cylindrical structure having an open space or hole in the center and a circular cross-section, resulting in a ring-shaped cross-section. The sleeve 133 is designed to fit around the outer side wall of the nozzle 108 and to be in physical contact with it. In this way, the sleeve 133 is positioned to fit around the top of the nozzle 108 and to be in physical contact with it. The bottom of the nozzle 108 extends downward from the lowest surface of the sleeve 133. The sleeve 133 may include a flange 131 around its peripheral portion, the flange 131 projecting perpendicular to the innermost side wall of the first portion 130a of the gas shroud. In one embodiment, the opening between the innermost side wall of the first portion 130a of the gas shroud and the flange 131 has a width W1. In one embodiment, the gas shroud 130 may or may not include a sleeve 133. In one embodiment where the sleeve 133 is not positioned to fit around the nozzle 108, the width W2 between the innermost side wall of the first portion 130a of the gas shroud and the nozzle 108 can be in the range of 1 mm to 30 mm. In one embodiment, the sleeve 133 may include a metal such as stainless steel or a high-temperature plasma-resistant alloy.

[0046] The gas shroud 130 may be positioned such that the lowest surface of the gas shroud 130 (e.g., a first portion of the gas shroud 130) is at the same height as the lowest surface of the nozzle 108 (e.g., the outlet). In other embodiments, the lowest surface of the gas shroud 130 is not at the same height as the lowest surface of the nozzle 108 (e.g., the outlet). The lowest surface of the gas shroud 130 may be above the upper surface of the wafer 126 by a height H3 in the range of 1 mm to 30 mm. The nozzle 108 is positioned inside the gas shroud 130 such that a gas exhaust port 109 (also called a space) is formed between the inner side wall of the gas shroud 130 and the outer side wall of the nozzle 108, and between the inner side wall of the gas shroud 130 and the outer side wall of the sleeve 133. The gas exhaust port 109 surrounds the peripheral portions of the outer side walls of the nozzle 108 and the sleeve 133. For example, the first portion of the gas exhaust port 109 includes a space between the innermost side wall of the first portion 130a of the gas shroud and the outermost side wall of the nozzle 108, as well as a space between the innermost side wall of the first portion 130a of the gas shroud and the sleeve 133 (including the flange 131). The second portion of the gas exhaust port 109 includes a space between the innermost side wall of the second portion 130b of the gas shroud and the sleeve 133. The third portion of the gas exhaust port 109 includes a space between the innermost side wall of the third portion 130c of the gas shroud and the sleeve 133. In one embodiment, the volume of the space in the third portion of the gas exhaust port 109 is greater than the volume of the space in the second portion of the gas exhaust port 109 and the volume of the first portion of the gas exhaust port 109.

[0047] Plasma and reactive species flowing from the plasma source 106 into the plasma processing chamber 114 travel through a nozzle 108. The outlet of the nozzle 108 is located above the upper surface of the wafer 126. The pressure P4 depends on both the plasma flow rate and the gas flow rate through the nozzle 108. A vacuum pump 120 is connected to a gas exhaust port 109 in the gas shroud 130 and is used to maintain the pressure P5 at the gas exhaust port 109 (hereinafter also referred to as the exhaust port). In one embodiment, the pressure P5 at the gas exhaust port 109 can be in the range of 0 Torr to 100 Torr. A vacuum pump 122 is connected to the plasma processing chamber 114 through a gas outlet and helps maintain the pressure P6 in region 115 of the plasma processing chamber 114 (shown earlier in Figure 3). The pressure P6 may hereafter be referred to as the chamber pressure and can be in the range of 10 Torr to 200 Torr. The gas shroud 130 is positioned above the top surface of the wafer 126 by a height H3 in the range of 1 mm to 30 mm.

[0048] During the etching process for etching material from wafer 126, plasma and reactive species are ejected from the outlet of nozzle 108 toward the upper surface of wafer 126 in the form of a plasma stream 112 (as described above in Figures 1 and 3). The plasma stream 112 moves away from the outlet of nozzle 108 (for example, vertically downward) until it encounters the upper surface of wafer 126 to be etched. Unreacted plasma (and reactive species), as well as gases and by-products generated from the etching process of wafer 126, may tend to move in the form of a flow 119 into region 115 of the plasma processing chamber 114.

[0049] Vacuum pump 120 is used to maintain pressure P5 at the gas exhaust port 109, and vacuum pump 122 is used to maintain pressure P6 in region 115 (shown earlier in Figure 3) of the plasma processing chamber 114. Pressure P4 at nozzle 108 is maintained by appropriately setting the flow rates of plasma and gas through nozzle 108. Pressure P5 at gas exhaust port 109 is maintained lower than pressure P6 in region 115 (shown earlier in Figure 3) of the plasma processing chamber 114. In various embodiments, the ratio of pressures P6 to pressure P5 can vary within the range of 2:1 to 100:1, for example, 10:1 to 20:1 in one embodiment. The relative pressure difference between pressures P6 and P5 allows the plasma and byproduct flow 119 to move relatively vertically upward, ensuring that it is discharged from the plasma processing chamber 114 through the gas exhaust port 109.

[0050] In various embodiments, advantages can be realized when the ratio of pressure P6 to pressure P5 varies in the range of 2:1 to 100:1, for example, in one embodiment, in the range of 10:1 to 20:1. These advantages include the ability to control the plasma flow immediately after impact with the wafer 126, and the immediate removal of all unreacted plasma (and reactive species) from the plasma processing chamber 114 through the gas exhaust port 109 adjacent to the nozzle 108. This ensures that the unreacted plasma (and reactive species) interacts only with a reduced area (e.g., a first region) on the upper surface of the wafer 126 before being removed from the plasma processing chamber 114. Thus, this enables high-resolution etching, better uniformity across the entire surface of the wafer 126, and reduced etching damage from unreacted plasma (and reactive species) to surrounding areas of the wafer 126 (e.g., other areas surrounding the first region) during the etching process.

[0051] In one embodiment, if the pressure P5 at the gas exhaust port 109 is kept lower than the pressure P6 in region 115 of the plasma processing chamber 114 (shown earlier in Figure 3), and the difference between pressure P6 and pressure P5 is kept within the range of 50 Torr to 200 Torr, the entire flow 119 moves vertically upward and is discharged from the plasma processing chamber 114 through the gas exhaust port 109. The flow 119 includes unreacted plasma (and reactive species), as well as gases and by-products generated from the etching process of the wafer 126. In addition, there is also a gas flow (flow 121) that exits the plasma processing chamber 114 from region 115 of the plasma processing chamber 114 through the gas exhaust port 109. Therefore, if the pressure P4 at nozzle 108, the pressure P5 at gas exhaust port 109, and the pressure P6 in region 115 of plasma processing chamber 114 are properly calibrated, gas exhaust port 109 functions as an adjacent exhaust port through which all unreacted plasma (and reactive species), as well as gases and by-products generated during the etching process of wafer 126, are removed from plasma processing chamber 114. The unreacted plasma (and reactive species), as well as gases and by-products generated during the etching process of wafer 126, are removed in the form of flow 119.

[0052] The advantages can be achieved by performing an etching process on a wafer 126 using a plasma processing system 100 comprising a gas shroud 130 and a nozzle 108, where the nozzle 108 is located inside and surrounded by the gas shroud 130. In addition, the plasma processing system 100 is used to maintain the pressure P4 at the nozzle 108, the pressure P5 at the gas exhaust port 109, and the pressure P6 in the region 115 of the plasma processing chamber 114 during the etching process, such that the pressure P5 at the gas exhaust port 109 is lower than the pressure P6 in region 115 of the plasma processing chamber 114, and the difference between pressure P6 and pressure P5 is maintained within the range of 50 Torr to 100 Torr. These advantages include the ability to control the plasma flow immediately after impact with the wafer 126, and the immediate removal of all unreacted plasma (and reactive species) from the plasma processing chamber 114 through the gas exhaust port 109 adjacent to the nozzle 108. This ensures that unreacted plasma (and reactive species) interact only with a reduced area (e.g., the first region) on the upper surface of the wafer 126 before being removed from the plasma processing chamber 114. This, in turn, enables high-resolution etching, better uniformity across the entire surface of the wafer 126, and reduced etching damage from unreacted plasma (and reactive species) to surrounding areas of the wafer 126 (e.g., other areas surrounding the first region) during the etching process.

[0053] In one embodiment, as shown in Figure 4, the second portion 130b of the gas shroud may have a porous side wall. For example, the side wall of the second portion 130b of the gas shroud may have a plurality of orifices 134 that directly connect the gas exhaust port 109 to the region 115 of the plasma processing chamber 114, allowing gas flow between them. The plurality of orifices 134 may be arranged at equal intervals, and each of the plurality of orifices 134 may have a diameter D1 in the range of 0.5 mm to 3 mm. In one embodiment, the third portion 130c of the gas shroud may also have a side wall having a plurality of orifices 134. When the pressure P5 at the gas exhaust port 109 is maintained lower than the pressure P6 in region 115 of the plasma processing chamber 114 (as shown earlier in Figure 3), the flow 119 moves vertically upward through an opening with a width W1 between the innermost sidewall of the first portion 130a of the gas shroud and the flange 131, and through the multiple orifices 134, and is exhausted from the plasma processing chamber 114 through the gas exhaust port 109. The flow 119 contains unreacted plasma (and reactive species), as well as gases and by-products generated from the etching process of the wafer 126. In addition, there is also a gas flow (flow 121) exiting the plasma processing chamber 114 from region 115 of the plasma processing chamber 114, through an opening with a width W1 between the innermost sidewall of the first portion 130a of the gas shroud and the flange 131, and through the multiple orifices 134.

[0054] The advantages can be realized by performing an etching process on a wafer 126 using a plasma processing system 100, which includes a gas shroud 130 and nozzles 108 as described above, wherein a second portion 130b of the gas shroud includes a side wall with multiple orifices 134 that directly connect the gas exhaust port 109 to a region 115 of the plasma processing chamber 114, allowing gas flow between them. When the pressure P5 at the gas exhaust port 109 is maintained lower than the pressure P6 in the region 115 of the plasma processing chamber 114 (shown earlier in Figure 3), the flow 119 moves vertically upward through an opening having a width W1 between the innermost side wall of the first portion 130a of the gas shroud and the flange 131, and through the multiple orifices 134, and is exhausted from the plasma processing chamber 114 through the gas exhaust port 109. The flow 119 includes unreacted plasma (and reactive species), as well as gases and by-products generated from the etching process of the wafer 126. Therefore, the flow 119 has multiple paths through which it passes to reach the gas exhaust port 109, which allows for a smoother flow 119 with reduced turbulence and friction as the flow 119 enters the gas exhaust port 109 and then exits the plasma processing chamber 114.

[0055] Further advantages can be realized by performing the etching process on the wafer 126 using a plasma processing system 100 equipped with the gas shroud 130 and nozzle 108 as described above, wherein the lowest surface of the gas shroud 130 (e.g., the first portion 130a of the gas shroud) is above the upper surface of the wafer 126 by a height H3 in the range of 1 mm to 30 mm. These advantages include the ability to enhance the removal of all unreacted plasma (and reactive species), as well as gases and by-products generated during the etching process of the wafer 126, into the gas exhaust port 109 from the plasma processing chamber 114.

[0056] Further advantages can also be realized by performing the etching process on the wafer 126 using the gas shroud 130. The gas shroud 130 comprises a third portion 130c of the gas shroud having an inner diameter D9 in the range of 40 mm to 100 mm and an outer diameter D10 in the range of 41 mm to 110 mm. The gas shroud 130 also comprises a first portion 130a of the gas shroud having an inner diameter D7 in the range of 20 mm to 60 mm and an outer diameter D8 in the range of 21 mm to 65 mm. These dimensions allow for an increase in the volume of space in the gas exhaust port 109 and improve the efficiency of removing unreacted plasma (and reactive species), as well as gases and by-products generated during the etching process of the wafer 126, from the plasma processing chamber 114. In addition, the gas shroud 130 having these dimensions allows for the gas shroud 130 to be manufactured more cost-effectively, with reduced manufacturing costs and improved ease of manufacture, resulting in shorter manufacturing times.

[0057] Figure 5 shows a schematic cross-sectional view of the plasma processing system 100 according to an alternative embodiment. Figure 6A shows a perspective view of the gas shroud 141 of the plasma processing system 100 shown in Figure 5. Figure 6B shows a perspective view of region 143 of the plasma processing system 100 shown in Figure 5. Figure 6B shows a hollow space 139 located between the gas shroud 141 and the wafer 126 of the plasma processing system 100 shown in Figure 5. The hollow space 139 may also include a space within the plasma nozzle and an exhaust outlet connected to the gas shroud 141, allowing gas flow into or from the gas shroud 141. Figure 7 shows a symmetrical cross-section representing one-eighth of the hollow space 139 shown in Figures 5 and 6B. The plasma processing system 100 of Figures 5 to 7 includes the features described above in Figures 1 to 4, as well as additional features that provide further advantages. Unless otherwise specified, similar reference numerals used in this embodiment (and subsequent embodiments) refer to similar components described and illustrated in Figures 1-4 and formed by similar processes. Therefore, process steps and applicable materials may not be repeated herein.

[0058] The plasma processing system 100 shown in Figures 5 to 7 may differ from the plasma processing system shown in Figures 1 to 4 in that the plasma processing system 100 does not include the outer annular portion 110 described in Figures 1 to 2 or the gas shroud 130 described in Figures 3 to 4. Instead, the plasma processing system 100 in Figures 5 to 6 includes a gas shroud 141.

[0059] The gas shroud 141 is positioned above the wafer support 117 and the wafer 126 within the plasma processing chamber 114. (Shown in Figure 6A) The gas shroud 141 has a circular shape when viewed from above, and may have a concave shape with a flat central portion 148. This means that the gas shroud 141 is curved or recessed around its edges, but the central portion 148 of the gas shroud 141 is flat or horizontal. The central portion 148 is lower than the edges of the gas shroud 141 and forms a recess or bowl-shaped form. The gas shroud 141 is fitted between the side walls of the plasma processing chamber 114 and is in physical contact with them so that the gas shroud 141 is positioned above the wafer 126 and the wafer support 117 (e.g., a wafer vacuum chuck). The central portion 148 may have an adjustable height such that the height H4 between the bottom surface of the central portion 148 and the top surface of the wafer 126 (as shown in Figure 7) is in the range of 2 mm to 30 mm. The outer portion 150 (hereinafter also called a baffle) of the gas shroud 141 may surround the central portion 148. The region of the outer portion 150 adjacent to the central portion 148 may have a height H5 between the bottom surface of the adjacent region and the top surface of the wafer 126 (as shown in Figure 7), and the height H5 is in the range of 2 mm to 50 mm. The hollow space 139 (shown in Figures 5, 6B, and 7) is located beneath the curved or concave sidewall of the gas shroud 141. This hollow space 139 is positioned between the gas shroud 141 and the wafer 126, and the hollow space 139 is connected to region 115 (shown in Figure 5) of the plasma processing chamber 114, allowing for the flow of gas into and out of region 115.

[0060] The gas shroud 141 may have a nozzle opening 147 (hereinafter also referred to as the plasma inlet), which is located above a central portion 148 and comprises an opening or hole extending through the central portion 148. Plasma and reactive species generated in the plasma source 106 flow into the plasma processing chamber 114 using a nozzle 151 that may extend through the nozzle opening 147 (shown in Figure 5). The nozzle opening 147 is positioned above a wafer support 117 (e.g., a wafer vacuum chuck) in the plasma processing chamber 114. The wafer support 117 is configured to hold a wafer 126 (or, for example, a substrate) to be etched so that reactive species and plasma are discharged toward the upper surface of the wafer 126 from the outlet of the nozzle 151 extending through the nozzle opening 147. The plasma and reactive species are guided toward the upper surface of the wafer 126 in the form of a plasma stream 112 at the outlet of the nozzle 151. The plasma stream 112 comprises a narrow column or stream of plasma and reactive species. The nozzle 151 extending through the nozzle opening 147 includes a tube or pipe having an annular cross-section. For example, the nozzle 151 may comprise a hollow cylindrical structure having an open space or hole in the center and a circular cross-section, resulting in a ring-shaped cross-section.

[0061] The gas shroud 141 may also have three or more exhaust openings 146 positioned above the central portion 148 and extending through the central portion 148. The exhaust openings 146 may be arranged radially around the nozzle opening 147. An exhaust outlet 149 may extend from each of the exhaust openings 146, and each exhaust outlet 149 may be inclined with respect to the vertical axis of the nozzle 151 extending through the nozzle opening 147 to improve the outflow of plasma reflected from the wafer. Thus, the exhaust outlets 149 are positioned or oriented in a circular or radial pattern around the nozzle 151. In various embodiments, the exhaust outlets 149 may be oriented at an angle of 30° to 60° with respect to the vertical axis of the nozzle 151. For example, the top of each exhaust outlet 149 may be further away from the vertical line AA (shown in Figure 7) passing through the center of the nozzle 151 than the bottom of the exhaust outlet 149. The angle of the exhaust outlets 149 may be selected to improve the outflow of plasma reflected from the wafer.

[0062] Each exhaust outlet 149 comprises a tube or pipe having an annular cross-section. For example, each exhaust outlet 149 may comprise a hollow cylindrical structure having an open space or hole in the center and a circular cross-section, resulting in a ring-shaped cross-section. Each exhaust outlet 149 may be positioned such that the corresponding exhaust opening 146 is above the upper surface of the wafer 126 and adjacent to the outlet of a nozzle 151 extending through a nozzle opening 147. In one embodiment, unreacted plasma (and reactive species), as well as gases and by-products generated during the plasma processing of the wafer 126, are removed from the plasma processing chamber 114 through the exhaust gas outlet 149. In one embodiment, the gas shroud 141 may include a material such as stainless steel or a high-temperature plasma-resistant alloy.

[0063] The vacuum pump 120 is connected to each of the exhaust outlets 149 and is used to remove unreacted plasma (and reactants), as well as gases and by-products generated during the plasma processing of the wafer 126, from the plasma processing chamber 114 through the exhaust outlets 149 and the gas outlets. Thus, the exhaust outlets 149 are exhaust ports from which unreacted plasma (and reactants), as well as gases and by-products generated during the plasma processing of the wafer 126, are removed from the plasma processing chamber 114. The unreacted plasma (and reactants), as well as gases and by-products, move through the exhaust outlets 149 in the form of a flow 119 (shown in Figures 5 and 7).

[0064] Vacuum pump 120 is connected to exhaust outlet 149 and is used to maintain pressure P8 at exhaust outlet 149. Vacuum pump 122 is connected to plasma processing chamber 114 through gas outlet and is used to maintain pressure P9 in region 115 (shown in Figure 5) of plasma processing chamber 114 and in the hollow space 139. Pressure P7 at nozzle 151 is maintained by appropriately setting the flow rates of plasma and gas through nozzle 151. In one embodiment, pressure P8 at exhaust outlet 149 can be in the range of 0 Tor to 20 Tor. Pressure P9, which may hereafter also be called chamber pressure, can be in the range of 200 Tor to 800 Tor. Pressure P8 at exhaust outlet 149 is maintained lower than pressure P9 in region 115 (shown in Figure 5) of plasma processing chamber 114 and in the hollow space 139. In various embodiments, the ratio of pressure P9 to pressure P8 can vary from 2:1 to 100:1, for example, from 10:1 to 20:1 in one embodiment. The relative pressure difference between pressure P9 and pressure P8 causes the plasma and byproduct flow 119 to move relatively vertically upward, ensuring that it is reliably discharged from the plasma processing chamber 114 through the exhaust outlet 149.

[0065] During the etching process for etching material from wafer 126, plasma and reactive species are ejected in the form of a plasma stream 112 from the outlet of nozzle 151 toward the upper surface of wafer 126. The plasma stream 112 moves away from the outlet of nozzle 151 (for example, vertically downward) until it encounters the upper surface of wafer 126 to be etched. Unreacted plasma (and reactive species), as well as gases and by-products generated from the etching process of wafer 126, may tend to move in the form of a flow 119 into region 115 of the plasma processing chamber 114.

[0066] In various embodiments, advantages can be realized when the ratio of pressure P9 to pressure P8 varies in the range of 2:1 to 100:1, for example, in one embodiment, in the range of 10:1 to 20:1. These advantages include the ability to control the plasma flow immediately after impact with the wafer 126, and the immediate removal of all unreacted plasma (and reactive species) from the plasma processing chamber 114 through the exhaust outlet 149 adjacent to the nozzle 151. This ensures that the unreacted plasma (and reactive species) interacts only with a reduced area (e.g., a first region) on the upper surface of the wafer 126 before being removed from the plasma processing chamber 114. Thus, this enables high-resolution etching, better uniformity across the entire surface of the wafer 126, and reduced etching damage from unreacted plasma (and reactive species) to surrounding areas of the wafer 126 (e.g., other areas surrounding the first region) during the etching process.

[0067] In one embodiment, if the pressure P8 at the exhaust outlet 149 is kept lower than the pressure P9 in the region 115 (shown earlier in Figure 5) of the plasma processing chamber 114 and the hollow space 139, and the difference between pressure P9 and pressure P8 is kept within the range of 200 Torr to 800 Torr, the entire flow 119 moves vertically upward and is discharged from the plasma processing chamber 114 and the hollow space 139 through the exhaust outlet 149. The flow 119 includes unreacted plasma (and reactive species), as well as gases and by-products generated from the etching process of the wafer 126. In addition, there is also a gas flow (flow 121) from the region 115 of the plasma processing chamber 114 and the hollow space 139, which exits the plasma processing chamber 114 through the exhaust outlet 149. Therefore, if the pressure P7 at nozzle 151, the pressure P8 at exhaust outlet 149, and the pressure P9 in region 115 of plasma processing chamber 114 and the hollow space 139 are properly calibrated, exhaust outlet 149 functions as an adjacent exhaust port through which all unreacted plasma (and reactive species), as well as gases and by-products generated during the etching process of wafer 126, are removed from plasma processing chamber 114 and the hollow space 139. The unreacted plasma (and reactive species), as well as gases and by-products generated during the etching process of wafer 126, are removed in the form of flow 119.

[0068] The advantages can be realized by performing an etching process on a wafer 126 using a plasma processing system 100 equipped with a gas shroud 141. The gas shroud 141 has exhaust openings 146 arranged radially around a nozzle opening 147. A nozzle 151 extends through the nozzle opening 147, and an exhaust outlet 149 extends from the corresponding exhaust opening 146. In addition, the plasma processing system 100 is used to maintain the pressure P7 at nozzle 151, the pressure P8 at exhaust outlet 149, and the pressure P9 at region 115 and hollow space 139 of the plasma processing chamber 114 during the etching process, such that the pressure P8 at exhaust outlet 149 is lower than the pressure P9 at region 115 and hollow space 139 of the plasma processing chamber 114, and the difference between pressure P9 and pressure P8 is maintained within the range of 200 Torr to 800 Torr. These advantages include the ability to control the plasma flow immediately after impact with the wafer 126, and the immediate removal of all unreacted plasma (and reactive species) from the plasma processing chamber 114 through the exhaust outlet 149 adjacent to the nozzle 151. This ensures that the unreacted plasma (and reactive species) interacts only with a reduced area (e.g., the first region) on the upper surface of the wafer 126 before being removed from the plasma processing chamber 114. This, in turn, enables high-resolution etching, better uniformity across the entire surface of the wafer 126, and reduced etching damage from unreacted plasma (and reactive species) to surrounding areas of the wafer 126 (e.g., other areas surrounding the first region) during the etching process.

[0069] Figure 8 shows a symmetrical cross-section representing one-eighth of the hollow space 139 of the gas shroud 141 of the plasma processing system 100. The gas shroud 141 of the plasma processing system 100 in Figure 8 includes the features described in Figures 5 to 7, as well as additional features that provide further advantages. Unless otherwise specified, similar reference numerals discussed in this embodiment (and embodiments discussed hereafter) represent similar components described and illustrated in Figures 5 to 7 and formed by similar processes. Accordingly, process steps and applicable materials may not be repeated herein.

[0070] The gas shroud 141 shown in Figure 8 may differ from the gas shrouds 141 shown in Figures 5-7 in that the exhaust outlet 149 is either omitted or completely blocked to restrict any gas flow entering and passing through the exhaust outlet 149. As a result, the flow 119 containing unreacted plasma (and reactive species), as well as gases and by-products generated during the etching process of the wafer 126, cannot move through the exhaust outlet 149. This, in turn, enhances the tendency for the unreacted plasma (and reactive species), as well as gases and by-products generated from the etching process of the wafer 126, to move into the region 115 and the hollow space 139 of the plasma processing chamber 114 in the form of flow 119.

[0071] The central portion 148 of the gas shroud 141 may have an adjustable height such that a height H4 (as shown in Figure 8) is maintained between the bottom surface of the central portion 148 and the top surface of the wafer 126 during the etching process of the wafer 126, with the height H4 ranging from 2 mm to 30 mm. The outer portion 150 (hereinafter also called a baffle) of the gas shroud 141 may surround the central portion 148. During the etching process of the wafer 126, the region of the outer portion 150 adjacent to the central portion 148 may be maintained at a height H5 between the top surface of the wafer 126 and the bottom surface of the adjacent region, with the height H5 ranging from 2 mm to 50 mm. By maintaining the heights H4 and H5 as described above, the temperature and pressure of the flow 119 can be controlled. For example, by maintaining the central portion 148 of the gas shroud 141 at a height H4, and the region of the outer portion 150 adjacent to the central portion 148 at a height H5, both the temperature and pressure of the flow 119 (e.g., the gas in the flow 119) may drop rapidly when the plasma stream 112 collides with the wafer 126. This occurs because, when the plasma stream 112 collides with the wafer 126 while it is under the gas shroud 141, the gas in the flow 119 cools rapidly and the pressure of the gas in the flow 119 drops rapidly. At these low temperatures and pressures, the unreacted plasma (and reactive species) in the flow 119 become inactive and are unable to etch surrounding regions of the wafer 126 (e.g., other regions surrounding the region to be etched) during the etching process.

[0072] Figure 9A shows traces 152A, 154A, and 156A, which are exemplary traces of temperature versus distance along the top surface of wafer 126, from a point on wafer 126 located vertically below the exit of nozzle 151. The point on wafer 126 is etched using the plasma stream 112 from the exit of nozzle 151. Traces 152a, 154a, and 156a represent different etching processes performed on different wafers 126 using gas shroud 141, with a different height maintained between the top surface of each wafer 126 being etched and the bottom surface of the outer portion 150 of the gas shroud 141 adjacent to the central portion 148 during each etching process. Trace 152A shows an etching process in which the maximum height is maintained between the top surface of the wafer 126 being etched and the bottom surface of the outer portion 150 of the gas shroud 141 adjacent to the central portion 148. Trace 156A shows an etching process in which a minimum height is maintained between the top surface of the wafer 126 being etched and the bottom surface of the outer portion 150 of the gas shroud 141 adjacent to the central portion 148. As can be seen from traces 152A, 154A, and 156A in Figure 9A, when using the gas shroud 141, the gas in the flow 119 is rapidly cooled as the plasma stream 112 collides with each wafer 126, resulting in the unreacted plasma (and reactive species) in the flow 119 becoming inert within a very short distance from the nozzle 151 exit and the plasma stream 112. Figure 9B shows exemplary traces of pressure versus distance along the top surface of the wafer 126, from a point on the wafer 126 vertically below the nozzle 151 exit. Each of the exemplary traces 152B, 154B, and 156B corresponds to the same etching process described by traces 152A, 154A, and 156A, respectively. As can be seen from the exemplary traces 152B, 154B, and 156B in Figure 9B, when the plasma stream 112 collides with each wafer 126, the gas in the flow 119 is rapidly cooled, resulting in a rapid decrease in pressure along with a change in the temperature of the gas in the flow 119.

[0073] The advantages can be realized by performing an etching process on a wafer 126 using a plasma processing system 100 equipped with a gas shroud 141. The gas shroud 141 is equipped with a nozzle 151 but has no exhaust outlet 149. During the etching process of wafer 126, a height H4 is maintained between the bottom surface of the central portion 148 and the top surface of wafer 126, and the height H4 is in the range of 2 mm to 30 mm. In addition, during the etching process of wafer 126, the region of the outer portion 150 adjacent to the central portion 148 is maintained to have a height H5 between the top surface of wafer 126 and the bottom surface of the adjacent region, and the height H5 is in the range of 2 mm to 50 mm. These advantages include the ability to control the plasma flow and characteristics immediately after impact with wafer 126. When the plasma stream 112 impacts wafer 126, both the temperature and pressure of the flow 119 (e.g., the gas in the flow 119) can drop rapidly. This occurs because, when the plasma stream 112 collides with the wafer 126 while it is under the gas shroud 141, the gas in the flow 119 cools rapidly, causing a rapid decrease in the pressure of the gas in the flow 119. At these low temperatures and pressures, the unreacted plasma (and reactive species) in the flow 119 becomes inactive at a short distance from the plasma stream 112. This ensures that the unreacted plasma (and reactive species) in the flow 119 interacts only with a reduced area (e.g., a first region) on the upper surface of the wafer 126 before it becomes inactive and can no longer further etch the wafer 126. Thus, this enables high-resolution etching, better uniformity across the entire surface of the wafer 126, and reduced etching damage from the unreacted plasma (and reactive species) to surrounding areas of the wafer 126 (e.g., other areas surrounding the first region) during the etching process.

[0074] While embodiments and their advantages of this disclosure have been described in detail, it should be understood that various modifications, substitutions, and alterations can be made without departing from the spirit and scope of this disclosure as defined by the attached claims.

[0075] Exemplary embodiments of the present invention are described below. Other embodiments can also be understood from the entirety of this specification and the claims submitted herein.

[0076] Example 1. The plasma processing apparatus includes a plasma source and a nozzle in a plasma chamber capable of guiding plasma from the plasma source onto a wafer to be processed. The plasma has the form of a plasma stream at the nozzle exit. The plasma processing apparatus also includes an outer annular portion positioned above the wafer in the plasma chamber and surrounding the nozzle, and a gas exhaust port positioned between the inner sidewall of the outer annular portion and the outer sidewall of the nozzle. The plasma processing apparatus further includes a first vacuum pump connected to the gas exhaust port between the inner sidewall of the outer annular portion and the outer sidewall of the nozzle.

[0077] Example 2. The plasma apparatus according to Example 1, further comprising a second vacuum pump connected to the plasma chamber, the second vacuum pump configured to maintain the plasma chamber at a second pressure, and the first vacuum pump configured to maintain the gas exhaust port at a first pressure.

[0078] Example 3. The plasma processing apparatus according to Example 2, wherein the second pressure is greater than the first pressure.

[0079] Example 4. The plasma processing apparatus according to Example 2 or 3, wherein the ratio of the second pressure to the first pressure is within the range of 10:1 to 20:1.

[0080] Example 5. A plasma processing apparatus according to one of Examples 2 to 4, wherein the first pressure is in the range of 0 Torr to 2 Torr, and the second pressure is in the range of 1 Torr to 100 Torr.

[0081] Example 6. A plasma processing apparatus according to one of Examples 1 to 5, wherein the outer diameter of the nozzle is in the range of 6 mm to 25 mm, and the outer diameter of the outer annular portion is in the range of 8 mm to 40 mm.

[0082] Example 7. A plasma processing apparatus according to one of Examples 1 to 6, wherein the bottom surface of the outer annular portion is located below the bottom surface of the nozzle.

[0083] Example 8. A plasma processing apparatus according to one of Examples 1 to 7, wherein the outer diameter of the outer annular portion changes perpendicularly along the axis of the outer annular portion.

[0084] Example 9. A plasma processing method comprises generating plasma from a plasma source and guiding the plasma into a processing chamber and onto the outer surface of a wafer using a nozzle. The plasma exits from the end of a nozzle positioned above the outer surface of the wafer, and the plasma exits in the form of a plasma stream. The nozzle extends through a gas shroud surrounding the nozzle and positioned above the wafer. A gas exhaust port is located between the inner sidewall of the gas shroud and the outer sidewall of the nozzle. The plasma processing method also comprises maintaining a first pressure at the gas exhaust port using a first vacuum pump and maintaining a second pressure in the processing chamber using a second vacuum pump. The first and second pressures are different.

[0085] Example 10. The method according to Example 9, wherein the first pressure is less than the second pressure.

[0086] Example 11. The method according to Example 9 or 10, wherein the difference between the second pressure and the first pressure is in the range of 50 Torr to 200 Torr.

[0087] Example 12. The method according to one of Examples 9-11, further comprising removing unreacted plasma from the processing chamber through a gas exhaust port after the plasma has been guided to the outer surface of the wafer.

[0088] Example 13. The gas shroud comprises a first part having a first outer diameter constant along the axis of the first part of the gas shroud, a second part having an outer diameter that varies along the axis of the second part of the gas shroud, and a third part having a second outer diameter constant along the axis of the third part of the gas shroud, wherein the second part of the gas shroud is positioned between the first part and the third part of the gas shroud, and the first part of the gas shroud is connected to the third part of the gas shroud, according to one of Examples 9 to 12.

[0089] Example 14. The method according to Example 13, wherein the second outer diameter is larger than the first outer diameter.

[0090] Example 15. The method according to Example 13 or 14, wherein the second portion of the gas shroud has a side wall including an orifice, the orifice enabling gas flow between the gas exhaust port and the area of ​​the processing chamber on the side of the side wall opposite the gas exhaust port.

[0091] Example 16. Apparatus comprising a plasma source and a gas shroud positioned above a wafer to be processed in a processing chamber. The gas shroud has a concave shape with a flat central portion. The apparatus also includes a nozzle extending through a first opening in the flat central portion and configured to deliver plasma from the plasma source to the outer surface of the wafer. The apparatus further includes a plurality of exhaust outlets extending from a second opening in the flat central portion and arranged radially around the nozzle.

[0092] Example 17. The apparatus as in Example 16, wherein the flat central portion is lower than the edge of the gas shroud.

[0093] Example 18. The apparatus according to Example 16 or 17, wherein the height between the top surface of the wafer and the bottom surface of the flat central portion is in the range of 2 mm to 30 mm.

[0094] Example 19. The apparatus according to one of Examples 16 to 18, further comprising a first vacuum pump connected to a plurality of exhaust outlets and configured to maintain a first pressure at each of the plurality of exhaust outlets, and a second vacuum pump connected to a processing chamber and configured to maintain a second pressure in the processing chamber, wherein the first pressure and the second pressure are different.

[0095] Example 20. The apparatus according to Example 19, wherein the ratio of the second pressure to the first pressure is within the range of 10:1 to 20:1.

[0096] Furthermore, the scope of this application is not intended to be limited to any specific embodiment of the processes, machines, products, material compositions, means, methods, and steps described herein. Those skilled in the art will readily understand from the disclosure that existing or future-developed processes, machines, products, material compositions, means, methods, or steps that perform substantially the same functions or achieve substantially the same results as the corresponding embodiments described herein may be utilized in accordance with this disclosure. Accordingly, the appended claims are intended to include within their scope such as the processes, machines, products, material compositions, means, methods, or steps.

Claims

1. Plasma source and A nozzle in a plasma chamber, wherein the nozzle is capable of guiding plasma from the plasma source to a wafer to be processed, and the plasma has the form of a plasma stream at the nozzle's outlet. The outer annular portion is disposed on the wafer within the plasma chamber and surrounds the nozzle, A gas exhaust port is positioned between the inner side wall of the outer annular portion and the outer side wall of the nozzle, A plasma processing apparatus comprising a first vacuum pump connected to the gas exhaust port between the inner side wall of the outer annular portion and the outer side wall of the nozzle.

2. The plasma apparatus according to claim 1, further comprising a second vacuum pump connected to the plasma chamber, wherein the second vacuum pump is configured to maintain the plasma chamber at a second pressure, and the first vacuum pump is configured to maintain the gas exhaust port at a first pressure.

3. The plasma processing apparatus according to claim 2, wherein the second pressure is greater than the first pressure.

4. The plasma processing apparatus according to claim 2, wherein the ratio of the second pressure to the first pressure is within the range of 10:1 to 20:

1.

5. The plasma processing apparatus according to claim 2, wherein the first pressure is in the range of 0 Tor to 2 Tor, and the second pressure is in the range of 1 Tor to 100 Tor.

6. The plasma processing apparatus according to claim 1, wherein the outer diameter of the nozzle is in the range of 6 mm to 25 mm, and the outer diameter of the outer annular portion is in the range of 8 mm to 40 mm.

7. The plasma processing apparatus according to claim 1, wherein the bottom surface of the outer annular portion is located below the bottom surface of the nozzle.

8. The plasma processing apparatus according to claim 1, wherein the outer diameter of the outer annular portion changes in a direction perpendicular to the axis of the outer annular portion.

9. A plasma processing method, Generating plasma from a plasma source, The method involves using a nozzle to guide the plasma into a processing chamber and onto the outer surface of a wafer, wherein the plasma exits from the end of the nozzle positioned above the outer surface of the wafer, the plasma exits in the form of a plasma stream, the nozzle extends through a gas shroud, the gas shroud surrounds the nozzle and is positioned on the wafer, and a gas exhaust port is positioned between the inner side wall of the gas shroud and the outer side wall of the nozzle. Using a first vacuum pump, maintain a first pressure at the gas exhaust port, A method comprising using a second vacuum pump to maintain a second pressure in the processing chamber, which is different from the first pressure and the second pressure.

10. The method according to claim 9, wherein the first pressure is less than the second pressure.

11. The method according to claim 10, wherein the difference between the second pressure and the first pressure is within the range of 50 Torr to 200 Torr.

12. The method according to claim 11, further comprising removing unreacted plasma from the processing chamber through the gas exhaust port after the plasma has been guided to the outer surface of the wafer.

13. The aforementioned gas shroud is, A first portion of the gas shroud having a first outer diameter that is constant along the axis of the first portion of the gas shroud, A second portion of the gas shroud, having an outer diameter that changes along the axis of the second portion of the gas shroud, The method according to claim 9, comprising: a third portion of the gas shroud having a second outer diameter constant along the axis of the third portion of the gas shroud, wherein the second portion of the gas shroud is positioned between the first portion of the gas shroud and the third portion of the gas shroud, and the first portion of the gas shroud is connected to the third portion of the gas shroud.

14. The method according to claim 13, wherein the second outer diameter is larger than the first outer diameter.

15. The method according to claim 13, wherein the second portion of the gas shroud has a side wall having an orifice, the orifice enabling gas flow between the gas exhaust port and the region of the processing chamber on the side of the side wall opposite to the gas exhaust port.

16. Plasma source and A gas shroud, which is placed on the wafer to be processed within the processing chamber and has a concave shape with a flat central portion, A nozzle extending through a first opening in the flat central portion and configured to deliver plasma from the plasma source to the outer surface of the wafer, The apparatus comprises a plurality of exhaust outlets extending from a second opening in the flat central portion and arranged radially around the nozzle.

17. The apparatus according to claim 16, wherein the flat central portion is lower than the edge of the gas shroud.

18. The apparatus according to claim 16, wherein the height between the upper surface of the wafer and the bottom surface of the flat central portion is within the range of 2 mm to 30 mm.

19. A first vacuum pump connected to the plurality of exhaust outlets and configured to maintain a first pressure at each of the plurality of exhaust outlets, The apparatus according to claim 16, further comprising a second vacuum pump connected to the processing chamber and configured to maintain a second pressure in the processing chamber, wherein the first pressure and the second pressure are different.

20. The apparatus according to claim 19, wherein the ratio of the second pressure to the first pressure is within the range of 10:1 to 20:1.

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