Etching process, processing method and semiconductor manufacturing system

Abstract

We have developed a new cyclic etching method, wet atomic layer etching (ALE), or wet (plasma) ALE, or nanomist (plasma) ALE, for damage-free and selective isotropic etching using mist / vapor / plasma at low temperatures. This method minimizes sputtering damage in plasma ALE, high-temperature volatilization in thermal ALE, and damage to nanostructures in wet ALE. The modified layer after mist or plasma reaction can be removed by dissolving it in a highly volatile mist stream. A mist-vapor phase or nanomist phase, which has intermediate properties between the liquid and vapor phases of mist and maintains the wet properties of the liquid phase with minimal mist size, is proposed here for nanodevice applications. By utilizing the Leidenfrost effect, the sample surface can be modified and / or etched by the floating nanomist-assisted vapor.

Description

[Technical Field]

[0001] This invention relates to a semiconductor manufacturing equipment and semiconductor device manufacturing method that uses a new etching method called wet atomic layer etching (ALE), also known as wet (plasma) ALE or nanomist (plasma) ALE, which uses mist / vapor / plasma to perform damage-free and selective isotropic etching at relatively low temperatures. This method minimizes damage caused by the sputtering effect in plasma ALE, high-temperature processing during the volatilization process in thermal ALE, and damage to nanostructures in wet ALE. The modified layer after the mist / vapor / plasma reaction can be removed by dissolving it in a highly volatile nanomist flow. [Background technology]

[0002] In the fabrication of next-generation field-effect transistors (FETs) for logic semiconductor devices, device dimensions are shrinking to a few nanometers. Therefore, selective etching of materials such as metals (W, Cu, Mo, Ru), metal carbides (TiAlC, TiC, AlC), metal nitrides (TiN, TiAlN, AlN), and alloys (TiAl, SiGe) without damage is a challenging task, necessitating the development of high-performance etching technologies. This technology is required for controlled isotropic etching and selective removal of multiple metal gate materials, consisting of metals or metal-containing compounds, in logic devices.

[0003] Traditional dry etching techniques use halogen-based plasma etchants for metals and metal compounds. However, for selective etching of metal compounds such as TiN, TiAl, and TiAlC over TiO, fluorine-based plasmas produce the nonvolatile product AlF3 (boiling point (bp) >1290 °C). Chlorine-based plasmas produce AlCl3 (bp approximately 183 °C) but also similar volatile products such as TiCl4 (bp ​​approximately 136 °C), resulting in poor etch selectivity. In addition to halogen-based etchants, non-halogen etchants derived from various precursor forms, including gases, liquids, and solid powders, offer a wide selection of environmentally friendly etchants for highly selectively producing volatile products.

[0004] In the atomic layer etching (ALE) process, the sample surface is first modified to reduce its surface energy, and then the modified layer with lower surface energy is removed in the second step. Currently, two common ALE techniques are plasma atomic layer etching and thermal atomic layer etching. The drawbacks of these two techniques are the sputtering effect in plasma ALE and the high temperature during the volatilization step in thermal ALE. Recently, a new wet ALE technique has been developed at room temperature, as described in [1]. In this wet ALE, a self-limiting passivation layer is formed by reacting with the surface modification liquid, and this passivation layer is then removed by dissolving it in another liquid. This wet ALE technique can overcome the problems associated with thermal ALE if the processing temperature can be lowered. However, the wet etching process suffers from poor reproducibility due to the destruction of nanopatterns during the drying process. To overcome the problems of both wet and dry etching, we propose wet-dry etching, or wet-state plasma etching, which combines the advantages of wet etching (high isotropy and selectivity) and dry etching (high controllability). By using a floating-wire-assisted vapor plasma generated at medium pressure, wet-state plasma containing a high density of reactive radicals can be remotely generated, significantly enhancing the chemical reaction rate on the sample surface. Therefore, wet-state plasma etching is applicable to isotropic etching of metals and metal compounds with high selectivity in next-generation atomic layer etching. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] C. Netzband et al., “Wet Atomic Layer Etching of Copper Structures for Highly Scaled Copper Hybrid Bonding and Fully Aligned Vias,” 2022 IEEE 72nd Electronic Components and Technology Conference, pages 707-711 [Non-patent document 2] Yaguchi et al, “Molecular Dynamics Study of Vapor-Liquid Equilibrium State of an Argon Nanodroplet and Its Vapor,” J. Fluid Science and Technology 2010, pages 180-191 Summary of the Invention [Problem to be solved by the invention]

[0006] Next-generation fin-type field-effect transistors and nanosheet-type field-effect transistors require the deposition of thin metal layers, which necessitates isotropic, damage-free, and selective etching. Current atomic layer etching has limitations, including sputtering effects caused by plasma ALE, high temperatures caused by thermal ALE, and damage to nanostructures caused by wet ALE. Therefore, new ALE methods that cause less damage to the sample surface are required. [Means for solving the problem]

[0007] We have developed a new dry etching method for damage-free and selective isotropic etching using mist / vapor / plasma, called wet atomic layer etching (ALE), wet (plasma) ALE, or nanomist (plasma) ALE. This process consists of two steps: Step 1 involves the formation of a self-limiting passivation layer using mist / vapor / plasma, and Step 2 involves the removal of this passivation layer by dissolving it in a low-temperature, highly volatile nanomist flow. Furthermore, we propose a mist-vapor (nanomist) phase, an intermediate phase between mist and vapor, where the mist size is minimal and the wet properties of the liquid phase are maintained, for nanodevice applications.

[0008] Etchants come in various forms, including gases, liquids, and solid powders. Gas etchants can be used directly for dry etching. Liquid etchants, on the other hand, can be used directly for wet etching, but cannot be used directly for dry etching. To use liquid etchants in dry etching, they are often used in vapor form. However, when attempting to use liquid etchants containing multiple components in dry etching, several challenges arise, as it is difficult to simultaneously vaporize the components while maintaining their original concentration ratios.

[0009] Generally, methods for obtaining mist / vapor from liquid etchants include heating the liquid, lowering the pressure in the chamber, and using ultrasonic vaporization. Among these methods, ultrasonic vaporization is suitable for obtaining mist / vapor at low temperatures for mixtures of multiple liquids whose individual liquids have different boiling points and vapor pressures and decompose even at low temperatures. However, this method has difficulties in generating ultrasonic vibrations, because ultrasonic vibrations are generated using a mist generator or device called an atomizer, which contains corrosive materials.

[0010] To prevent the ultrasonic transducer from reacting with corrosive etching solutions (e.g., H2O2, acids, and alkalis), which could contaminate the mist, we developed a non-contact atomizer that transmits ultrasound from the ultrasonic transducer through an aqueous medium to a specially designed liquid container. To achieve uniform etching, it is important to control the ratio of chemicals in each mist droplet obtained from the mixed solution, as well as the size of the mist.

[0011] To maintain the wettability of the mist (liquid phase) and ensure deep penetration of the mist into the complex interior of nanodevices with small dimensions, we propose an intermediate phase between mist and vapor, termed the mist-vapor phase or nanomist phase. The mist-vapor phase or nanomist phase can maintain the wettability of the liquid phase even at the smallest mist size. There are several methods to reduce the mist size, including using high ultrasonic frequencies (megasonic frequencies), adding carrier or dilution gases, using a vacuum chamber to lower the operating pressure below atmospheric pressure, heating the sample surface, or heating the chamber walls to gasify the mist. By using a vacuum chamber, the operating pressure can be controlled to be lower than atmospheric pressure. Lowering the operating pressure reduces the mist size to nanoscale, while simultaneously lowering the mist's surface tension, allowing it to more easily penetrate into the nanopatterns of nanodevices. To maintain the mist properties, a medium pressure is preferred.

[0012] Here, we use a technique called cyclic etching. For atomic layer etching, surface modification is controlled by first treating the surface with nanomist / vapor or plasma-activated nanomist / vapor. Cyclic etching can be performed in a self-limiting manner, using mist / vapor or plasma-activated mist / vapor to form a liquid layer on the sample surface, which is then removed by a low-temperature, highly volatile mist flow, thereby modifying the sample surface.

[0013] Plasma is a source of ions, radicals, etc. At medium pressures (0.2 kPa to 50 kPa), plasma behaves like a fluid, mainly generating radicals that reach the sample surface and cause isotropic etching. Another novel ALE method here uses plasma to modify the sample surface and then removes this modified layer by dissolving it in a cold, highly volatile nano-mist stream (methanol, ethanol, or isopropanol).

[0014] This application discloses the best examples of wet atomic layer etching (ALE), or wet (plasma) ALE, or nanomist (plasma) ALE, for damage-free and selective isotropic etching using mist / vapor / plasma at low temperatures. The mist-vapor or nanomist can be generated by a non-contact atomizer. The size of the mist-vapor can be controlled by the carrier gas / dilution gas and the operating pressure of the vacuum chamber. Self-limiting passivation layers can be removed by dissolving them in the nanomist or plasma-activated nanomist stream. [Effects of the Invention]

[0015] The advantages of the exemplary configurations of the present invention disclosed herein are as follows: According to embodiments of the present invention, a new dry etching technology, called wet etching, wet (plasma) etching, or nanomist (plasma) etching, can be provided for damage-free, selective, isotropic etching using mist / vapor / plasma at low temperatures in a continuous or cyclic etching manner. Highly selective etching of materials such as metals or metal compounds can be achieved through various mist- or plasma-based surface reactions. Modified layers can be removed by dissolving them in a low-temperature, highly volatile nanomist flow, minimizing damage compared to high-temperature processing using thermal ALE. In addition to gas or plasma etchants, other etchants can be used in mist form from various precursors (liquid or powder) generated by an atomizer, allowing for a wide selection of environmentally friendly etchants. Importantly, an intermediate phase between mist and vapor, termed the mist-vapor phase or nanomist phase, which has the smallest mist size and can maintain the wet properties of the liquid phase, is proposed here for nanodevice applications. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 shows an example of a floating nanomist-assisted vapor atomic layer etching method or a Leidenfrost atomic layer etching method. [Figure 2] 1A-1C illustrate an example of a plasma activated nano-mist atomic layer etching method. [Figure 3] FIG. 1 illustrates an example of combining plasma and nanomist atomic layer etching methods. [Figure 4] FIG. 10 shows an example of removing a modified layer by dissolving it in a highly volatile nanomist flow during wet (plasma) atomic layer etching. [Figure 5]This figure shows an example of nanomist generation on a substrate surface at various substrate temperatures. The nanomist generated on the sample surface varies depending on the substrate temperature. In the non-boiling state, it is a single-phase nanomist, in the transition boiling state, bubbles / nanomist / vapor coexist, and in the film boiling state, a dual phase of nanomist / vapor film is formed. [Figure 6] FIG. 1 shows an example of nanomist floating on a cushion of its own vapor at the Leidenfrost point. [Figure 7] Figure 1 shows an example of wet ALE using a floating nanomist-assisted vapor film based on the Leidenfrost effect. [Figure 8a] FIG. 1 illustrates a method for producing mist / vapor from a liquid. [Figure 8b] FIG. 1 shows the generation of mist / vapor from a ternary (A, B and C) mixture. [Figure 9] FIG. 1 illustrates how to reduce the mist size and optimize the mist-vapor size by controlling the working pressure of the vacuum chamber. [Figure 10] FIG. 1 is a diagram showing a schematic diagram of a non-contact atomizer using an ultrasonic vibrator to generate nanomist. [Figure 11a] 1A-1C show examples of various designs of precursor or liquid containers used in contactless atomizers for generating nanomist. [Figure 11b] 1A-1C show examples of various designs of precursor or liquid containers used in contactless atomizers for generating nanomist. [Figure 11c] 1A-1C show examples of various designs of precursor or liquid containers used in contactless atomizers for generating nanomist. [Figure 11d] 1A-1C show examples of various designs of precursor or liquid containers used in contactless atomizers for generating nanomist. [Figure 12]Figure 1 shows the dependence of TiAlC film thickness on exposure time to (NH4OH, HO2, HO) mist obtained from a mixture of (NH4OH, HO2, HO) at room temperature and atmospheric pressure using a non-contact atomizer with a mist filter. [Figure 13] This is a diagram showing the mist / vapor / plasma system combined with a vacuum chamber. [Figure 14] FIG. 1 shows a plasma activated mist / vapor system combined with a vacuum chamber. [Figure 15] Figure 1 shows a mist / vapor / plasma system combined with a spectrometer to measure the reaction of the mist / vapor / plasma with the sample surface during the etching process. [Figure 16] FIG. 1 shows thermography images of nanomist being generated by a non-contact atomizer connected to a 20 kPa vacuum chamber. [Figure 17] Figure 11 shows the dependence of substrate temperature on the film thickness change of TiAlC during nanomist etching at an operating pressure of 20 kPa and an exposure time of 10 min. [Figure 18a] FIG. 1 shows the X-ray photoelectron spectra of Ti2p, Al2p, C1s, O1s, N1s, and Si2p of untreated TiAlC. [Figure 18b] FIG. 10 shows X-ray photoelectron spectra of Ti2p, Al2p, C1s, O1s, N1s, and Si2p of the nanomist-treated TiAlC sample at an operating pressure of 20 kPa, an exposure time of 10 min, no filter, and 25° C. [Figure 18c] Figure 10 shows the X-ray photoelectron spectra of Ti2p, Al2p, C1s, O1s, N1s, and Si2p of the nanomist-treated TiAlC sample at an operating pressure of 20 kPa, an exposure time of 10 min, with a filter, and at 25 °C. [Figure 18d]Figure 1 shows X-ray photoelectron spectra of Ti2p, Al2p, C1s, O1s, N1s, and Si2p of a nanomist-treated TiAlC sample at an operating pressure of 20 kPa, an exposure time of 10 min, with a filter, and at 100 °C. [Figure 18e] Figure 1 shows X-ray photoelectron spectra of Ti2p, Al2p, C1s, O1s, N1s, and Si2p of a nanomist-treated TiAlC sample at an operating pressure of 20 kPa, an exposure time of 10 min, with a filter, and at 175 °C. DETAILED DESCRIPTION OF THE INVENTION

[0017] The inventors of the present invention have been attempting to develop a new dry etching technology called wet atomic layer etching, or wet (plasma) atomic layer etching, or nanomist (plasma) atomic layer etching, which is performed at low temperatures to minimize damage caused by the sputtering effect in plasma ALE, high-temperature treatment during the volatilization process in thermal ALE, and damage to nanostructures in wet ALE. As a result, the inventors have discovered the following: (1) We successfully obtained H2O2 mist from a mixture of (H2O2, H2O) at room temperature. The boiling points of H2O2 and H2O are 150.2°C and 100°C, respectively. (2) For TiAlC etching, we successfully obtained (NH4OH, H2O2, and H2O) mist from a mixture of (NH4OH, H2O2, and H2O) at room temperature using a non-contact atomizer. The boiling points of NH4OH, H2O2, and H2O are 37.7°C, 150.2°C, and 100°C, respectively. (3) To prevent the corrosive liquid (etchant) from reacting with the ultrasonic vibrator, the atomizer was designed so that the liquid does not come into contact with the ultrasonic vibrator (non-contact atomizer). (4) The material, thickness, and shape of the liquid (or precursor) container used in the non-contact atomizer were examined and optimized to generate mist effectively. (5) To achieve uniform etching, the non-contact atomizer was designed with a mist filter to obtain uniform mist size. (6) TiAlC was etched by combining nanomist (NH4OH, H2O2, and H2O) generated by a non-contact atomizer equipped with a filter with a vacuum chamber controlled at medium pressure. (7) When a TiAlC substrate was heated to the Leidenfrost point in a mixture of (NH4OH, H2O2, and H2O), the TiAlC was etched by the floating nanomist-assisted vapor of (NH4OH, H2O2, and H2O).

[0018] The best mode of the present invention will now be described with reference to Figures 1 to 18e.

[0019] <Process Example 1> The first embodiment will be described with reference to Figures 1 to 4. This paper describes an example of a new dry etching technique called wet-type ALE, wet-type (plasma) ALE, or nanomist (plasma) ALE, which is performed at low temperatures and minimizes the sputtering effect in plasma ALE, the damage caused by high-temperature processing in the volatilization process in thermal ALE, and the damage to nanostructures in wet ALE.

[0020] Figure 1 shows an example of the floating nanomist-assisted vapor atomic layer etching method, or Leidenfrost atomic layer etching method. The "floating nanomist-assisted vapor" method, which utilizes the Leidenfrost effect as shown in Figure 7, will be explained in detail later. First, the sample surface is exposed to a floating nanomist-assisted vapor film to form a liquid layer for surface modification. This liquid layer is then removed by dissolving it in a flow of highly volatile nanomist, such as a nanomist of methanol, ethanol, or isopropanol.

[0021] An example of the floating-wire-assisted vapor plasma-activated nanomist atomic layer etching method is shown in Figure 2. First, the sample surface is exposed to plasma-activated nanomist for surface modification, forming a liquid layer, which is then removed by dissolving it in a stream of highly volatile nanomist, such as methanol, ethanol, or isopropanol nanomist.

[0022] Figure 3 shows an example of combining plasma and nanomist atomic layer etching methods. First, the sample surface is exposed to plasma to form a modified layer, which is then removed by dissolving it in a flow of highly volatile nanomist, such as a nanomist of methanol, ethanol, or isopropanol.

[0023] Figure 4 shows an example of removing a modified layer during wet (plasma) atomic layer etching by dissolving it in a highly volatile nanomist flow. After forming a modified layer on the sample surface, it is removed by dissolving it in a highly volatile nanomist flow, such as a nanomist of methanol, ethanol, or isopropanol.

[0024] <Process Example 2> The second embodiment will be described with reference to Figures 5 to 9. The characteristics of the nanomist and the generation of nanomist on a substrate that varies depending on the temperature will be described together with the generation of floating nanomist-assisted vapor at the Leidenfrost point for application to wet ALE.

[0025] Figure 5 shows an example of nanomist generation on a substrate surface at various substrate temperatures. Nanomist generation may vary depending on the substrate temperature. In the non-boiling state, the substrate temperature is lower than the boiling point, and single-phase nanomist is generated. It is possible to perform wet etching using a liquid layer composed of nanomist. Similar to conventional wet etching, a liquid layer composed of nanomist behaves as a liquid layer with surface tension, resulting in pattern collapse in nanodevices, making it unsuitable for application to nanodevices. Even in this state, it goes without saying that current nanomist technology, like conventional wet etching, can be applied to applications other than nanodevices.

[0026] In the transition boiling state, the substrate temperature is above the boiling point but below the Leidenfrost point, and bubbles, nanomist, and vapor coexist. Bubbles are generated within the coexisting nanomist, and vapor is generated when these bubbles burst. There are several problems with properly controlling the etching uniformity in this state. While this invention does not address these issues in depth, it may be possible to solve these problems by optimizing the composition of the raw materials for the nanomist to some extent.

[0027] At the film boiling state, the substrate temperature exceeds the Leidenfrost point, forming a nanomist / vapor dual phase. At the Leidenfrost point, the nanomist floats stably on a continuous, uniform cushion of its own vapor with frictionless motion. In this state, the continuous, uniform vapor film facilitates uniform etching. A wet-state ALE can be achieved using the floating nanomist-assisted vapor film to form an extremely thin reactive film (modified layer) on the sample surface.

[0028] Figure 6 shows an example of nanomists floating on a stable cushion of their own vapor at the Leidenfrost point. At the Leidenfrost point, nanomists drift and move across the substrate surface for the longest possible time. The nanomists float on their own vapor cushion with frictionless motion across the entire sample surface, forming an extremely thin liquid-like layer. The floating nanomists assisted vapor deposition enables uniform wet etching without pattern collapse. Even at temperatures above the boiling point, the evaporation of the floating nanomists is slow, resulting in a long residence time in the vapor layer, which accelerates the reaction rate due to the high-temperature acceleration effect. Furthermore, etchant molecules consumed in the vapor layer are quickly replenished by the floating nanomists, which have an accelerated mass flux between the nanomists and the vapor layer at higher temperatures. This also contributes to the higher reaction rate. In other words, when the substrate temperature reaches the Leidenfrost point, the nanomists function as a temporary source of etchant for the vapor film to react directly with the sample surface. Additionally, the volume and shape of the nanomist allows more etchant molecules to remain on the sample surface and be pushed by the weight or mass of the nanomist, resulting in less etchant being lost as it flows off the sample surface.

[0029] Figure 7 shows an example of wet-type ALE using a floating nanomist-assisted vapor film based on the Leidenfrost effect. The wet-type ALE process consists of two steps: the first step is surface modification using floating nanomist-assisted vapor A, and the second step is reaction layer removal using floating nanomist-assisted vapor B.

[0030] In the first step, the nanomist moves frictionlessly and floats on a cushion of its own vapor across the entire sample surface at the Leidenfrost point. A stable vapor film A forms beneath the floating nanomist, acting as an insulating film that suppresses heat transfer from the substrate surface to the nanomist, slowing the evaporation rate of the nanomist and ensuring the longest lifespan. At the Leidenfrost point, the nanomist pushes against the cushion film of its own vapor, reacting with the sample surface over the widest contact area and for the longest period of time. This is similar to the reaction that occurs in a pressure cooker and provides the optimal conditions for forming an extremely thin reaction film in the shortest time.

[0031] In the second step, the reaction layer is removed by floating nanomist-assisted vapor B. The reaction products desorb from the sample surface, dissolve in floating nanomist B, and are removed together with floating nanomist B. Nanomist B should preferably be a highly volatile, low-reactivity material. If nanomist B easily reacts with the sample surface, it may cause undesirable damage to the substrate. After absorbing the reaction products, frictionless nanomist or non-contact nanomist can remove them more easily than high-contact nanomist without a boiling point, thus achieving a clean surface and a controllable cyclic process.

[0032] To lower the Leidenfrost point, one can increase the ambient temperature by baking the chamber to compensate for the heat loss at the mist surface (top of the mist), or one can reduce the operating pressure or reduce the mist size to obtain a metastable Leidenfrost nanomist.

[0033] Figure 8a shows a method for generating nanomist from a liquid. For etching applications, a mist or vapor form is required. The conventional method for generating mist or vapor from a liquid is to heat or boil the liquid. Another conventional method is to connect a liquid container to a vacuum chamber and control the vapor pressure in the vacuum chamber to obtain vapor. Ultrasonic vibrations at frequencies ranging from several hundred kilohertz (kHz) to several megahertz (MHz) can be used to generate mist. An additional carrier gas may be used to generate bubbles or control the direction of the mist.

[0034] Figure 8b illustrates the generation of mist / vapor from a three-component mixture (A, B, and C). For mixtures consisting of multiple components, such as NH4OH, HO2, and HO, which have different boiling points and vapor pressures and are prone to decomposition even at low temperatures, ultrasonic vibration using an atomizer is a suitable method for obtaining a "cold" mist / vapor at room temperature. Vaporization of a three-component mixture (A, B, and C) produces vapors of each component, which can exist independently without ionic bonds. The combinatorial effect achieved by mixing these three chemical components (A, B, and C) in the wet phase would be lost. In the nanomist form, the intermediate phase between mist and vapor (nanomist) can maintain the three chemical components A, B, and C while maintaining ionic interactions between them, thereby maintaining the combinatorial effect achieved by mixing these three chemical components in the wet phase while minimizing the mist size. In this invention, the desired mist size is 0.5 to 10 nm. When the mist size is smaller than 0.5 nm, the combinatorial effect of mixing these three chemical components in the wet phase is lost, making it difficult to maintain an intermediate phase between mist and vapor. Furthermore, when the mist size is larger than 10 nm, the mist, especially the micromist, loses its vapor properties, making it difficult to maintain an intermediate phase between mist and vapor. Achieving a mist-vapor phase allows for control of the mist size and chemical composition ratio within each mist droplet, achieving uniform etching suitable for nanodevices. Micromist is a collection of three chemicals (A, B, and C). The combinatorial effect of mixing these three chemical components in the wet phase is maintained while maintaining ionic interactions among the three components. However, large, nonuniform mists (>100 nm, i.e., "submicron") are generated, making them unsuitable for nanodevice applications.

[0035] To determine the size of the mist, the mist was introduced into a wide-range particle spectrometer. In this study, the inventors used a WPS, Model 1000XP, manufactured by MSP. Needless to say, other known particle spectrometers may also be used for this purpose. For measurements in the 10 to 10,000 nm range, the mist was set at a constant flow rate, e.g., 1.00 liters / min (standard liters / min, slm), of which 0.7 slm passed through a laser particle spectrometer (LPS) for particle size analysis by laser light scattering. The remaining 0.30 slm passed through a differential mobility analyzer (DMA) and a condensation particle counter (CPC) to measure the size of aerosol particles down to a 10 nm limit. By increasing the aerosol flow rate through the DMA and CPC to 0.45 slm, measurements down to a 5 nm limit could be performed. This also increases the total flow rate of mist passing through the WPS to 1.15 L / min.

[0036] The uniformity of the nanomist etching reaction on the sample surface was analyzed using atomic force microscopy (AFM). The surfaces of samples, including untreated samples, nanomist-modified surface samples, and nanomist-etched surface samples, were observed and compared. When the mist size is sufficiently large and contacts the sample surface with high surface tension, as described above in the left diagram of Figure 5, it is not possible to form an extremely thin film, leaving large holes on the sample surface that are clearly visible with AFM. Furthermore, when the mist size is sufficiently small, such as within the 0.5 to 10 nm range, AFM images of the etched surface show a uniform, flat surface without large holes. These nanomists, with diameters in the 0.5 to 10 nm range, have extremely low surface tension due to the nanosize effect, which is described in detail in Non-Patent Document 2. These nanomists can also react with the sample surface without direct wet contact, as described in the right diagram of Figure 5.

[0037] Figure 9 illustrates a method for optimizing the mist-vapor phase by controlling the operating pressure of the vacuum chamber to achieve the desired mist size. To maintain the wet properties of the mist (liquid phase) and to reduce the vapor to a microscopic size suitable for nanodevice applications, it is important to control the mist size within the aforementioned range (0.5 to 10 nm). To obtain nanomists with the desired droplet size, acoustic frequencies between several hundred kilohertz and several megahertz are preferred. More specifically, frequencies in the range of 1.0 to 10 MHz are more preferred. The mist size can also be reduced by adding carrier and dilution gases (N, Ar, or He). To achieve the Leidenfrost effect, it is desirable to generate and use an intermediate phase between the mist and vapor or nanomist phases under temperature-controlled conditions on the sample surface. At the Leidenfrost point, the sample surface reacts with the floating nanomist-assisted vapor, forming an extremely thin liquid-like layer. In this embodiment, the mist-vapor phase is obtained by controlling the operating pressure to an optimal pressure (medium pressure).

[0038] In order to introduce mist into nanopatterns on nanodevices, the surface tension of the mist is also crucial, in addition to the mist size. The surface tension of the mist varies depending on the mist diameter. For mist with a diameter of 10 nm or less, the surface tension is too small to be measured. This is discussed in detail in Non-Patent Document 2. Furthermore, when the mist diameter is 10 nm or less and under the conditions of the Leidenfrost effect, the mist droplets do not adhere to the device surface, and the surface tension of the mist does not affect the nanopattern on the nanodevice. Therefore, in this embodiment, the nanomist has a desirable droplet size, which minimizes the collapse of the nanopattern and improves the reproducibility of nanodevice fabrication. The surface tension of the mist decreases as the size decreases. If a mist-vapor phase can be achieved, it is possible to achieve a minimum-sized nanomist with low surface tension, increasing the possibility of etching nanodevices. Furthermore, choosing a mist with high volatility (low boiling point), such as a mist of methanol, ethanol, or isopropanol, which has low surface tension, is considered a good way to dissolve the residue or modified layer and leave no residue. Dissolution and removal (etching / cleaning) may be performed simultaneously.

[0039] <Process Example 3> An example of generating mist from a single liquid and a mixture of multiple liquids using a non-contact atomizer will be described with reference to FIGS. 10 to 12. FIG.

[0040] Figure 10 is a schematic diagram of a non-contact atomizer using an ultrasonic vibrator to generate nanomist, suitable for the present invention. Ultrasonic vibrations can be used at frequencies ranging from several hundred kilohertz (100 kHz to 950 kHz) to several megahertz (1.6 to 2.4 MHz) to generate the mist. Megasonic frequencies are preferred for generating nanomist, with 1.7 MHz or 2.4 MHz being the most preferred due to the practical availability of corresponding ultrasonic generators. Because this is a non-contact atomizer, the ultrasonic waves must penetrate the water and coolant medium and then travel through the precursor or liquid container to the liquid used as the etchant raw material. Therefore, it is important to consider and optimize the material, thickness, and shape of the liquid container.

[0041] Although polypropylene and some polymer-based materials are superior to glass materials in generating mist as materials for liquid containers, polymer-based materials have a low melting point and may melt if the liquid level in the container is very low. Therefore, in the present invention, glass is one of the materials far superior to polymer-based materials for use in liquid containers due to its high melting point and high resistance to chemicals.

[0042] The shape of the liquid container should be rounded to maximize the efficiency of mist generation in the present invention by concentrating the ultrasonic energy to obtain the maximum transmitted energy at the liquid surface. When this transmitted energy exceeds the mist generation threshold, mist is generated. If the bottom of the liquid container is flat, the transmitted energy will be spread more evenly across the liquid surface, resulting in more large droplets, less efficient mist generation, and increased heat loss at the container wall.

[0043] The thickness of the liquid container, particularly the thickness of the bottom wall through which ultrasonic waves propagate, is crucial for effectively generating the nanomist desired in this invention. While aluminum metal is not a suitable material for transmitting ultrasonic waves, aluminum foil with a thickness of approximately 10 μm to 100 μm can effectively generate mist. In this invention, the material selected for making the liquid container is glass. To generate nanomist with the desired diameter in this invention, a thin glass container with a bottom thickness in the range of 0.3 mm to 2 mm is preferred. Glass containers with a bottom thickness greater than 2 mm significantly reduce the efficiency of mist generation and generate waves, mainly on the liquid surface, resulting in serious heat loss at the bottom wall of the container. Glass containers with a bottom thickness less than 0.3 mm are difficult to manufacture and are prone to breakage.

[0044] To achieve a uniform nanomist and prevent large droplets from forming, an additional side port filter is designed. This side port faces away from the center of the liquid container and faces the container wall, so that mist with undesirable diameters is filtered out and the desired nanomist can pass through the filter. The side port filter may have an inner diameter of the port ranging from 5 mm to 15 mm.

[0045] To prevent large droplets from forming and to filter a uniform nanomist, a filter with a mesh size of 0.1 mm to 1 mm made of a hydrophobic material or a material coated with a waterproof material such as polytetrafluoroethylene (PTFE) may be used.

[0046] To achieve a smaller, more uniform nanomist, a membrane filter with a mesh size of 100 nm to 500 nm made of a hydrophobic material or a material coated with a waterproof material such as polytetrafluoroethylene (PTFE) can be used. For nanomists of aqueous mixtures such as NH4OH, HO2, and HO, controlling the size of the mist is crucial in this invention to control the ratio of each chemical component. Changing the size of the mist can alter the ratio of the components. To achieve uniform etching, it is necessary to control the uniformity of the nanomist size using a mist filter.

[0047] Figures 11a through 11d each show examples of different types of precursor containers or glass liquid containers that can be used in contactless atomizers to generate the desired nanomist. Here, we describe four types of liquid containers that can be used in contactless atomizers.

[0048] Type 1 (Figure 11a) is a glass liquid container used in a non-contact atomizer to generate the desired nanomist using a carrier gas and dilution gas (He, Ar, or N2). The side port filter is designed with an inner diameter of 5 to 10 mm to prevent large droplets from being generated as a by-product of the ultrasonic transducer. A refill port is provided at the top of the container for adding liquid. The liquid level is controlled between 20 and 40% of the container height to prevent large droplets from being generated and mist from condensing on the side port filter. A liquid level higher than 40% results in excessive condensation on the side port. A liquid level lower than 20% facilitates mist generation, but requires more frequent precursor replenishment. The liquid level is preferably controlled at 30% of the container height. To optimize the ultrasonic energy transfer to the liquid surface and maximize mist generation efficiency, it is necessary to optimize the optimal wave energy transfer point M. The optimal wave energy transmission point M is the point at which the maximum ultrasonic wave energy exceeding the mist generation energy threshold can be transmitted to the liquid surface, and is the origin of mist generation (mist generation point). This point is located on the liquid level line. Because the bottom of the container has a rounded shape, ultrasonic energy waves can be more confined to the liquid surface at the center of the liquid level line. However, because the liquid level is highest and the center of the container's bottom is thicker due to the container manufacturing process, ultrasonic energy transmission to the liquid surface is not optimal. In this invention, the optimal wave energy transmission point M is located approximately 5 to 20 mm away from the center of the liquid level line. The position of the side port (MS line) is designed to be away from the normal (MV line) so that the angle α of the wave energy transmission point M on the liquid surface is optimized to be 30 to 60 degrees to prevent the generation of large, high-temperature droplets simultaneously with nanomist and cool mist. The center of the ultrasonic transducer is located on the MV line. To generate mist for a long time, it is better to apply a waterproof coating (hydrophobic coating) on ​​the surface of the side port filter to reduce the problem of mist condensation.This waterproof coating repels the aqueous mist generated by the atomizer.

[0049] Type 2 (Figure 11b) is a glass liquid container used in a non-contact atomizer to generate nanomist using a carrier gas and dilution gas (He, Ar, or N2). Liquid can be refilled using the carrier / dilution gas port or the nanomist port. The liquid level is controlled between 20% and 40% of the container's height to prevent large droplets and condensation of mist at the nanomist port. A liquid level higher than 40% increases condensation at the nanomist port. A liquid level lower than 20% facilitates mist generation, but requires more frequent precursor refills. The liquid level is preferably controlled at 30% of the container's height. A PTFE filter with a mesh diameter of 0.1 to 1 mm is installed near the mist outlet line to remove large droplets and achieve a uniform nanomist. A mesh diameter less than 0.1 mm increases condensation. A mesh diameter greater than 1 mm results in more nonuniform droplet size and larger droplets. In the present invention, it is preferable to use a PTFE filter with a mesh size of 0.5 mm.

[0050] Type 3 (Figure 11c) is a glass liquid container used in a non-contact atomizer for generating nanomist using a carrier gas and a dilution gas (He, Ar, or N2). Liquid can be replenished using either the carrier / dilution gas port or the nanomist port. The side port filter is designed with an inner diameter between 5 and 15 mm to prevent large droplets from being generated by the ultrasonic transducer. The liquid level is controlled between 20 and 40% of the container height to prevent large droplets from being generated and mist from condensing on the side port filter. A liquid level higher than 40% results in excessive condensation on the side port. A liquid level lower than 20% facilitates mist generation but requires more frequent precursor replenishment. It is preferable to control the liquid level at 30% of the container height. Other problems may arise, such as reduced mist generation efficiency, increased heat loss at the container wall, and increased generation of large droplets. In order to optimize the transmission of ultrasonic energy to the liquid surface and maximize the mist generation efficiency, it is necessary to optimize the optimal wave energy transmission point M. The optimal wave energy transmission point M is the point at which the liquid surface can receive the maximum ultrasonic wave energy that exceeds the mist generation energy threshold, and is the origin of mist generation (mist generation point). This point is located on the liquid level line. Because the bottom of the container has a rounded shape, ultrasonic energy waves can be more limited at the liquid surface at the center of the liquid level line. However, because the liquid level is highest and the center of the container's bottom is thicker due to the container manufacturing process, the transmission of ultrasonic energy to the liquid surface is not optimal. In the present invention, the optimal wave energy transmission point M is located approximately 10 to 20 mm away from the center of the liquid level line. The position of the side port (MS line) is designed to be away from the normal (MV line) so that the angle α of the wave energy transmission point M on the liquid surface is optimized to be between 30 and 60 degrees in order to prevent the generation of large, high-temperature droplets simultaneously with the nano-mist and cool mist. The center of the ultrasonic transducer is located on the MV line.To generate mist for a long time, it is better to apply a waterproof coating on the surface of the side port filter to reduce the problem of mist condensation. This waterproof coating repels the aqueous mist generated by the atomizer.

[0051] Type 4 (Figure 11d) is a glass liquid container used in a non-contact atomizer for generating nanomist using a carrier gas and a dilution gas (He, Ar, or N2). Liquid can be replenished using either the carrier / dilution gas port or the nanomist port. The side port filter is designed with an inner diameter between 5 and 15 mm to prevent large droplets from being generated by the ultrasonic transducer. The liquid level is controlled between 20 and 40% of the container height to prevent large droplets from being generated and mist from condensing on the side port filter. A liquid level higher than 40% results in excessive condensation on the side port. A liquid level lower than 20% facilitates mist generation but requires more frequent precursor replenishment. The liquid level is preferably controlled at 30% of the container height. Other problems may arise, such as reduced mist generation efficiency, increased heat loss at the container wall, and increased generation of large droplets. In order to optimize the transmission of ultrasonic energy to the liquid surface and maximize the mist generation efficiency, it is necessary to optimize the optimal wave energy transmission point M. The optimal wave energy transmission point M is the point at which the liquid surface can receive the maximum ultrasonic wave energy that exceeds the mist generation energy threshold, and is the origin of mist generation (mist generation point). This point is located on the liquid level line. Because the bottom of the container has a rounded shape, ultrasonic energy waves can be more limited at the liquid surface at the center of the liquid level line. However, because the liquid level is highest and the center of the container's bottom is thicker due to the container manufacturing process, the transmission of ultrasonic energy to the liquid surface is not optimal. In the present invention, the optimal wave energy transmission point M is located approximately 10 to 20 mm away from the center of the liquid level line. The position of the side port (MS line) is designed to be away from the normal (MV line) so that the angle α of the wave energy transmission point M on the liquid surface is optimized to be between 30 and 60 degrees in order to prevent the generation of large, high-temperature droplets simultaneously with the nano-mist and cool mist. The center of the ultrasonic transducer is located on the MV line.A PTFE filter with a mesh size of 0.1 to 1 mm near the mist outlet line removes large droplets to produce a uniform nanomist. Mesh sizes less than 0.1 mm tend to result in condensation. Mesh sizes greater than 1 mm result in more nonuniform droplet sizes and larger droplets. In this invention, a PTFE filter with a mesh size of 0.5 mm is preferred. To generate mist over a long period of time, a waterproof coating on the surface of the side port filter is recommended to reduce the problem of mist condensation. This waterproof coating repels the aqueous mist generated by the atomizer.

[0052] Figure 12 shows the experimental results of the dependence of film thickness on exposure time to nanomist of a ternary aqueous mixture of NH4OH, HO2, and HO at room temperature and atmospheric pressure. Increasing the exposure time to the nanomist decreased the thickness of the TiAlC film. The film thickness was estimated using ellipsometry. The etch rate of TiAlC by the (NH4OH, HO2, and HO) mist was 0.15 nm / min.

[0053] <Process Example 4> A fourth embodiment will be described with reference to Figure 13. An example of a mist / vapor / plasma system combined with a vacuum chamber for surface modification and etching purposes will be described.

[0054] Figure 13 shows a diagram of a mist / vapor / plasma system combined with a vacuum chamber. Room-temperature nanomist generated by a non-contact atomizer is flowed into the vacuum chamber. The mist size can be controlled by adding carrier and dilution gases (He, Ar, or N2) to prevent recombination of the nanomist or by varying the operating pressure of the vacuum chamber. Plasma treatment in the vacuum chamber can be performed using plasma sources such as capacitively coupled plasma, inductively coupled plasma, microwave plasma, and floating-wire-assisted plasma. Multi-step processes can be performed for plasma or nanomist treatment (surface modification) and nanomist treatment (removal of the modified layer by dissolving it in the highly volatile nanomist stream). The operating pressure can be controlled at a medium pressure (0.2 kPa to 50 kPa), in which case the nanomist stream behaves like a fluid (while maintaining its wetting properties), and the mist size can be controlled within a range suitable for etching nanodevices. The substrate temperature can be controlled using previously known methods, such as a circulator or infrared lamp. By heating the substrate to an appropriate temperature range where the Leidenfrost effect appears, all droplets in the nanomist do not adhere to the surface of the device, and the surface tension of the mist does not affect the nanopattern of the nanodevice. The nanomist in the chamber has beam scattering properties, but with some ingenuity, the plasma characteristics can be measured using several types of spectrometers, such as an optical emission spectrometer.

[0055] Figure 14 shows a diagram of a plasma-activated mist / vapor system combined with a vacuum chamber. A remote plasma source is introduced into the atomizer of the mist section, and nanomist is activated by incorporating certain radicals into the nanomist. For example, oxygen radicals O are generated by remote oxygen plasma. * is generated, which is taken up by (NH4OH and HO) and *and HO) may be generated to replace the HO in the mist (NH4OH, HO2, and HO). Because HO2 solutions are corrosive and explosive, especially at high concentrations (greater than 30%), replacement gases or plasma may be preferable in practice. Plasma (He plasma or Ar plasma) may be used to activate the mist, generating a negatively charged mist that can be accelerated by an electric field. By providing a positive charge to the sample surface, the negatively charged mist can reach the sample surface more uniformly and effectively. The plasma-activated nanomist obtained by a non-contact atomizer is then passed into a vacuum chamber. The size of the mist may be controlled by adding a carrier gas and diluent gas (He, Ar, or N2) to prevent recombination of the nanomist or by varying the operating pressure of the vacuum chamber. The operating pressure may be controlled to a medium pressure (0.2 kPa to 50 kPa), in which case the nanomist stream behaves as a fluid (while maintaining its wetting properties), and the mist size may be controlled to a range of values ​​suitable for etching nanodevices. The substrate temperature may be controlled by known methods such as a circulator or an infrared lamp.

[0056] FIG. 15 shows a mist / vapor / plasma system in combination with one of the spectrometers listed below. (1) Optical emission spectrometer (OES) for measuring plasma characteristics (2) A spectroscopic ellipsometer (SE) for analyzing the modification of the sample surface and the change in the sample film thickness. (3) Fourier-transform infrared spectrometer (FTIR) for analyzing sample surface modifications (4) X-ray photoelectron spectrometer (XPS) for analyzing sample surface modifications (5) A quadrupole mass spectrometer (QMS) for analyzing the composition of the nanomist / plasma and the volatile products generated from the sample surface during reaction with the mist / plasma. (6) Thermal desorption spectroscopy (TDS) for analyzing desorption products generated by heating nanomist / vapor / plasma-treated sample surfaces.

[0057] The nanomist at room temperature obtained by a non-contact atomizer is flowed into a vacuum chamber. A plasma source is introduced into the atomizer in the mist section, and the nanomist is activated by incorporating certain radicals into it. For example, oxygen radicals O * is generated, which is taken up by (NH4OH and HO) and *and HO) may be generated to replace HO in the (NH4OH, HO2, and HO) mist. The nanomist may be activated by plasma (He plasma or Ar plasma) to generate a negatively charged mist that can be accelerated by an electric field. The plasma-activated nanomist obtained by a non-contact atomizer is then flowed into a vacuum chamber. The mist size may be controlled by adding a carrier gas and a dilution gas (He, Ar, or N2) to prevent recombination of the nanomist or by changing the operating pressure of the vacuum chamber. The operating pressure may be controlled to a medium pressure (0.2 kPa to 50 kPa), in which case the nanomist stream behaves like a fluid (while maintaining its wetting properties), and the mist size may be controlled within a range suitable for etching nanodevices. Plasma sources such as capacitively coupled plasma, inductively coupled plasma, microwave plasma, and floating-wire-assisted plasma may be used for plasma processing. A multi-step process may be performed to perform plasma-activated nanomist treatment (surface modification) and nanomist treatment (removal of the modified layer by dissolving it in a highly volatile nanomist flow). The substrate temperature may be controlled by known methods, such as a circulator or infrared lamps.

[0058] Figure 16 shows thermography images showing some typical experimental results when generating nanomist using a non-contact atomizer (Type 2 in Figure 12) connected to a 20 kPa vacuum chamber. Because a non-contact atomizer is used to generate nanomist, the temperatures of the liquid and mist are close to room temperature, and there is little temperature change during mist generation. 15 minutes after generating the nanomist, the temperature of the liquid is lower than 30°C, and the temperature of the mist is also lower than 30°C.

[0059] Figure 17 shows the dependence of substrate temperature on the change in TiAlC film thickness during nanomist etching at an operating pressure of 20 kPa and an exposure time of 10 min. Increasing the substrate temperature increases the etching rate. At a temperature of 175 °C, the etching rate of the TiAlC film is highest, at 0.02 nm / min. 175 °C is considered the Leidenfrost point of the nanomist generated from the aqueous mixture of (NH4OH, HO2, and HO) at 20 kPa, and the TiAlC surface was etched by the floating nanomist-assisted vapor of the (NH4OH, HO2, and HO) mixture.

[0060] Figures 18a through 18e show typical experimental results, including Ti2p, Al2p, C1s, O1s, and N1s X-ray photoelectron spectra, respectively, for (a) untreated TiAlC and TiAlC samples treated with nanomist at a working pressure of 20 kPa for 10 minutes. The results are shown for (b) 25°C without a filter, (c) 25°C with a filter, (d) 100°C with a filter, and (e) 175°C with a filter. Without the PTFE filter, surface oxidation occurs on the TiAlC surface, resulting in the replacement of Ti(Al)-C bonds with Ti(Al)-O bonds. The N1s spectrum, derived from ammonium hydroxide residue, is also observed. With the PTFE filter, etching occurs at 100°C and 175°C, but the surfaces of the etched samples are as clean as those of the untreated samples. Using a PTFE filter during sequential mist etching may result in no mist residue.

Claims

1. An etching method, comprising: A first step of generating a phase having properties intermediate between the liquid phase and the vapor phase of a mist by using an atomizer; a second step of exposing the sample surface to a phase having a first composition with properties intermediate between the liquid and vapor phases of the mist to produce a surface-modified layer; a third step of exposing the surface-modified layer produced in the second step to a phase having a second composition with properties intermediate between the liquid and vapor phases of a mist; a fourth step of heating the substrate surface prior to the second step or the third step so that the temperature of the substrate surface is higher than the boiling point of each component of the first composition or the second composition, respectively; An etching method comprising:

2. An etching method, comprising: A first step of generating a phase having properties intermediate between the liquid phase and the vapor phase of a mist by using a non-contact atomizer having a mist filter; a second step of exposing the sample surface to a phase having a first composition with properties intermediate between the liquid and vapor phases of the mist to produce a surface-modified layer; a third step of removing the surface-modified layer formed in the second step by exposing the surface-modified layer to a phase having a second composition with properties intermediate between the liquid phase and the vapor phase of the mist, and dissolving the surface-modified layer formed in the second step into the phase; a fourth step of heating the substrate surface prior to the second step or the third step so that the temperature of the substrate surface is higher than the boiling point of each component of the first composition or the second composition, respectively; An etching method comprising:

3. 3. The etching method according to claim 1, wherein the sample surface is exposed to the plasma.

4. 3. The etching method according to claim 1, wherein the plasma activation is performed on the mist phase having properties intermediate between the liquid phase and the vapor phase.

5. 3. The etching method according to claim 1, wherein the mist phase, which has properties intermediate between the liquid phase and the vapor phase, contains nanodroplets having a diameter of 0.5 nm to 10 nm.

6. 3. The etching method according to claim 1, wherein the atomizer is a type of ultrasonic atomizer, and the ultrasonic vibration of the ultrasonic atomizer operates in the range of several hundred kilohertz to several megahertz.

7. 3. The etching method according to claim 2, wherein the non-contact atomizer has a liquid container made of glass and having a rounded bottom wall thickness in the range of 0.3 to 2.0 mm.

8. 3. The etching process of claim 2, wherein the non-contact atomizer is designed with a side port filter at the side port of the atomizer to prevent the large, hot droplets from being generated simultaneously with the nano-mist and cool mist.

9. 9. The etching method according to claim 8, wherein the side port is positioned at an angle of 30 to 60 degrees away from a normal to the liquid surface at the mist generation point in order to prevent the large, high-temperature droplets from being generated simultaneously with the nano mist and cool mist.

10. 9. The etching process of claim 8, wherein the sideport filter has an inner diameter in the range of 5 mm to 15 mm.

11. 3. The etching method according to claim 2, wherein the non-contact atomizer has a mist filter to prevent the large, high-temperature droplets from being generated simultaneously with the nano-mist and cool mist, and the mist filter is provided so as to directly face the surface of the liquid or precursor.

12. 12. The etching method according to claim 11, wherein the mist filter has a mesh diameter in the range of 0.1 mm to 1 mm.

13. 13. The etching method according to claim 11 or 12, wherein the mist filter has a surface made of a hydrophobic material.

14. 14. The etching method according to claim 13, wherein the mist filter is a PTFE filter.

15. 3. The etching method according to claim 2, wherein the non-contact atomizer has a membrane-type mist filter for obtaining a uniform nano-sized mist, and the mist filter is provided in a mist discharge line.

16. 16. The etching method according to claim 15, wherein the membrane mist filter has a mesh size ranging from 100 nm to 500 nm.

17. 17. The etching method according to claim 15 or 16, wherein the membrane mist filter has a surface made of a hydrophobic material.

18. 18. The etching method according to claim 17, wherein the membrane mist filter is a PTFE membrane filter.

19. 8. The etching method according to claim 7, wherein the liquid container is filled with liquid whose liquid level is controlled to effectively generate mist and prevent condensation of the mist.

20. 20. The etching method according to claim 19, wherein the liquid container is filled with the liquid to a height ranging from 20% to 40% of the height of the liquid container.

21. 4. The etching method according to claim 3, wherein the modified layer is formed by exposing the sample surface to the plasma.

22. The phase having properties intermediate between the liquid phase and the vapor phase of the mist is ２ O ２ 3. The etching method according to claim 1, wherein the etching solution is produced from an aqueous mixture containing:

23. The phase having properties intermediate between the liquid phase and the vapor phase of the mist is the following precursor: an aqueous mixture consisting of multiple components with different boiling points; Water-based liquids containing corrosive materials, Aqueous liquids containing materials that are susceptible to decomposition even at low temperatures, and of aqueous liquids containing high boiling point materials 3. The etching method according to claim 1, wherein the etching is performed from one of the above.

24. 3. The etching method according to claim 1, wherein the surface temperature of the substrate is heated to the Leidenfrost point of the liquid filled in the liquid container of the atomizer.

25. 25. The etching method according to claim 24, wherein the sample surface is modified by floating nanomist-assisted vapor to form a liquid modified layer, and then the surface modified layer is removed by another floating nanomist-assisted vapor.

26. 1. A semiconductor manufacturing system, comprising: A vacuum chamber; A non-contact atomizer for obtaining a phase having intermediate properties between the liquid phase and vapor phase of a mist from the liquid filled in a liquid container; a carrier gas line and a gas flow controller, both connected to the non-contact atomizer; an operating pressure controller that sets the vacuum chamber at a medium pressure at which the mist, which has intermediate properties between the liquid phase and the vapor phase, behaves as a fluid; an infrared lamp for controlling the detachment of the modified layer; a heating and cooling circulator for controlling the temperature of the substrate; a spectrometer for performing measurements within the vacuum chamber; A semiconductor manufacturing system comprising:

27. 1. A semiconductor manufacturing system, comprising: A vacuum chamber; A non-contact atomizer for obtaining a phase having intermediate properties between the liquid phase and vapor phase of a mist from the liquid filled in a liquid container; a carrier gas line and a gas flow controller, both connected to the non-contact atomizer; a plasma source for exposing to the plasma; an operating pressure controller that sets the vacuum chamber at a medium pressure at which the mist, which has intermediate properties between the liquid phase and the vapor phase, behaves as a fluid; an infrared lamp for controlling the detachment of the modified layer; a heating and cooling circulator for controlling the temperature of the substrate; a spectrometer for performing measurements within the vacuum chamber; A semiconductor manufacturing system comprising:

28. 30. The semiconductor manufacturing system of claim 27, wherein the plasma source for providing the plasma exposure comprises a floating wire-assisted plasma source.

29. 29. The semiconductor manufacturing system of claim 28, wherein a floating wire-assisted plasma is used to activate the phase of the mist having properties intermediate between the liquid phase and the vapor phase, thereby generating a negatively charged mist.

30. 30. The semiconductor manufacturing system of claim 29, wherein the sample surface is provided with a positive charge for effectively attracting the negatively charged mist.

31. The spectrometer comprises: an optical emission spectrometer (OES) for measuring the characteristics of the plasma; a spectroscopic ellipsometer (SE) for analyzing sample surface modifications and changes in sample film thickness; a Fourier-transform infrared spectrometer (FTIR) for analyzing sample surface modifications; an X-ray photoelectron spectrometer (XPS) for analyzing the modification of the sample surface; a quadrupole mass spectrometer (QMS) for analyzing the composition of the nanomist / plasma and the volatile products generated from the sample surface during reaction with the mist / plasma; and A temperature programmed desorption analyzer (TDS) for analyzing desorption products generated by heating a nanomist / vapor / plasma treated sample surface. : thermal desorption spectroscopy), 28. The semiconductor manufacturing system according to claim 26 or 27, wherein the semiconductor manufacturing system is selected from the group consisting of:

32. 28. The semiconductor manufacturing system according to claim 26 or 27, wherein the temperature of the substrate is heated to the Leidenfrost point of the liquid filled in the liquid container.

33. A processing method comprising: A step of modifying a sample surface by first floating nano-mist assisted vapor, wherein a first processing gas containing nano-mists having a diameter smaller than a predetermined value is supplied, the nano-mists being generated from a liquid of a first composition; removing the modified layer from the sample surface by a second floating nano-mist assisted vapor, wherein a second process gas containing nano-mists having a diameter smaller than the predetermined value is supplied, the nano-mists being generated from a liquid of a second composition; A processing method comprising:

34. 34. The processing method according to claim 33, wherein the nanomist contained in the first processing gas or the second processing gas has a diameter of less than 10 nm.

35. 34. The processing method according to claim 33, wherein each of the first processing gas and the second processing gas has properties intermediate between the liquid phase and the vapor phase of mist.

36. 34. The processing method according to claim 33, further comprising: applying ultrasonic vibrations to the liquid of the first composition to generate a nano-mist contained in the first processing gas; and applying ultrasonic vibrations to the liquid of the second composition to generate a nano-mist contained in the second processing gas.

37. 34. The method of claim 33, wherein the first composition and the second composition are both aqueous.

38. 34. The processing method according to claim 33, wherein the first processing gas and the second processing gas are supplied through a filter so that the diameter of nano-mists contained in the first processing gas and the second processing gas is smaller than the predetermined value.

39. 34. The processing method of claim 33, wherein the first processing gas comprises a plasma activated nanomist.

40. 34. The method of claim 33, further comprising heating the sample surface such that the temperature of the substrate surface is above the boiling point of each component of the first composition or the second composition.

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