KR20220117946A - Atomic layer etching method using liquid precursor - Google Patents

Abstract

According to an embodiment of the present invention, provided is an atomic layer etching method using a liquid etching precursor which can achieve the almost same effect even at a relatively high temperature compared to conventional atomic layer etching using a cryogenic temperature. In addition, provided is the atomic layer etching method which can prevent process problems that may be accompanied by a liquid precursor.

Description

Atomic layer etching method using liquid precursor {ATOMIC LAYER ETCHING METHOD USING LIQUID PRECURSOR}

The present invention relates to an atomic layer etching method using a liquid precursor.

In general, a semiconductor device manufacturing process is made to repeatedly perform various unit processes, such as a thin film deposition process, an etching process, a cleaning process, and a photo process, on a substrate such as a wafer.

With the miniaturization and integration of semiconductor devices, design rules have been further reduced in the design of semiconductor integrated circuits in recent years, and critical dimensions of nanometer level are required. In order to realize such a nanometer-level semiconductor device, precise control of the etching process is essential, and research on atomic layer etching (ALE), which is one of the etching methods for precision etching, is being actively conducted.

Atomic layer etching includes a cycle consisting of adsorption, purge, desorption, and purge, among which an object to be etched may be etched by adsorption and desorption processes. Theoretically, one layer can be etched with one cycle, and the cycle can be repeated until the desired depth is reached. In addition, since the atomic layer etching has a self-limited characteristic in which the reaction is automatically stopped when the surface is saturated, it has the advantage of accurately removing as many layers as desired.

1 is a diagram illustrating an example of a conventional atomic layer etching.

1(a) is a diagram illustrating a first-generation atomic layer etching process. First-generation atomic layer etching is characterized by adsorption using plasma. Ions, electrons, and photons in plasma collide with the substrate, causing physical and electrical damage to the substrate. there is a problem with

1(b) is a diagram illustrating a second-generation atomic layer etching process. The second-generation atomic layer etching is characterized in that the precursor is adsorbed by cooling the substrate to cryogenic temperature. Physical damage is not applied to the substrate, but there is a difficulty in cooling the substrate to -100°C or less, thereby There is a problem that thermal damage may occur. In addition, a problem of contamination of the substrate may occur due to the low-temperature adsorption principle.

In a nanometer-class semiconductor device, physical and electrical damage to the substrate by plasma is a factor of a decrease in productivity by lowering the reliability of the device, and cooling the substrate to cryogenic temperatures is also very inefficient in terms of cost and time.

Accordingly, an object of the present invention is to provide an atomic layer etching method capable of performing an atomic layer etching process at room temperature without damaging a substrate.

In addition, an atomic layer etching method having higher precision and preventing damage to a substrate as compared to conventional atomic layer etching may be provided.

Problems to be solved are not limited thereto, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

According to an embodiment of the present invention, vaporizing the etching precursor maintained in a liquid phase and supplying it to the chamber; an adsorption step in which the etching precursor is adsorbed to the substrate surface; a first purge step of purging the inside of the chamber by supplying an inert gas into the chamber after the adsorption step; a desorption step of etching the substrate by generating plasma in the chamber; After the desorption step, a second purge step of purging the inside of the chamber by supplying an inert gas into the chamber; may be provided.

The etching precursor is a material having a boiling point of 0° C. or higher at atmospheric pressure, and may be one of a fluorocarbon (CF)-based compound, which is a compound of carbon and fluorine.

Alternatively, the etching precursor may be a material having a boiling point of 0° C. or higher at atmospheric pressure, and may be one of a hydrofluorocarbon (HFC) system, which is a compound of carbon, fluorine, and hydrogen.

The etching precursor may be vaporized in a bubbling manner by a vibrator.

In the first purge step, the remaining precursors other than the precursor adsorbed on the surface of the substrate may be discharged to the outside of the chamber.

Alternatively, the first purge step may include generating plasma by supplying a weaker power than the desorption step.

The adsorption step may include a temperature control step of the substrate.

The atomic layer etching method may further include a chamber wall heating step of heating the chamber wall temperature to a temperature higher than a boiling point of the etching precursor.

The chamber wall heating step may be performed at least during the adsorption step.

The chamber wall heating step may be performed by electromagnetic waves.

The chamber wall heating step may be performed by any one light source of an IR lamp, a UV lamp, a halogen lamp, an LED, an incandescent lamp, and a fluorescent lamp.

According to an embodiment of the present invention, a chamber providing a substrate processing space; a support unit for supporting the substrate; An atomic layer etching apparatus may be provided that includes a gas supply unit that vaporizes the etching precursor maintained in a liquid phase and supplies it into the chamber, and the gas supply unit includes a canister for storing the liquid precursor.

The canister may include a vibrator for vibrating the liquid precursor, and the liquid precursor may be vaporized in a bubbling manner using the vibrator.

The etching precursor is a material having a boiling point of 0° C. or higher at atmospheric pressure, and is one of a fluorocarbon (CF)-based compound of carbon and fluorine or a hydrofluorocarbon (HFC)-based compound of carbon, fluorine, and hydrogen. can be

The atomic layer etching apparatus may further include a chamber heating unit for heating the chamber wall.

The chamber heating unit may heat the wall surface of the chamber to a temperature higher than a boiling point of the etching precursor.

According to the embodiment of the present invention, atomic layer etching without damage to the substrate is possible at room temperature using a liquid precursor with good adsorption, so it is relatively efficient in process time and cost and prevents contamination and damage to the substrate can do.

Effects of the present invention are not limited thereto, and other effects not mentioned will be clearly understood by those skilled in the art from this specification and the accompanying drawings.

1 is a view for explaining a conventional atomic layer etching.
2 is a diagram illustrating an etching processing apparatus for performing an etching process according to an embodiment of the present invention.
FIG. 3 is an enlarged view for explaining the gas supply unit of FIG. 2 .
4 is a flowchart illustrating an etching processing method according to an embodiment of the present invention.
5 is a diagram for explaining the principle of atomic layer etching according to an embodiment of the present invention.
6 is a table for explaining optimization according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement them. However, the present invention may be embodied in various other forms and is not limited to the embodiments described herein.

In describing an embodiment of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the specific description is omitted, and parts with similar functions and actions are omitted. The same reference numerals are used throughout the drawings.

At least some of the terms used in the specification are defined in consideration of functions in the present invention, and thus may vary according to user, operator intention, custom, and the like. Therefore, the terms should be interpreted based on the content throughout the specification.

In addition, in the specification, when a certain component is included, this means that other components may be further included, rather than excluding other components, unless otherwise stated. And, when it is said that a part is connected (or coupled) with another part, it is not only directly connected (or coupled), but also indirectly connected (or coupled) with another part therebetween. include

On the other hand, in the drawings, the size or shape of the component, the thickness of the line, etc. may be expressed somewhat exaggerated for the convenience of understanding.

Embodiments of the present invention are described with reference to a schematic illustration of ideal embodiments of the present invention. Accordingly, changes from the shape of the diagram, for example, changes in manufacturing methods and/or tolerances, are those that can be fully expected. Accordingly, embodiments of the present invention are not to be described as being limited to the specific shapes of the areas described as diagrams, but rather to include deviations in shape, the elements described in the drawings are schematic in nature and their shapes are not elements It is not intended to describe the precise shape of these, nor is it intended to limit the scope of the present invention.

As shown in FIG. 2 , an etching apparatus for performing an atomic layer etching process according to an embodiment of the present invention includes a substrate processing unit 1 and a gas supply unit 2 .

The substrate processing unit 1 may include a chamber 100 , a substrate support unit 200 , a gas supply unit 300 , a plasma generation unit 400 , and a chamber heating unit 500 . The etching processing apparatus according to an embodiment of the present invention may be an inductively coupled plasma apparatus.

The chamber 100 provides a processing space for etching the substrate W therein. The etching process may be performed in a vacuum atmosphere. The chamber 100 may be provided to be hermetically sealed, and an entrance (not shown) may be formed on a side wall. The substrate W may be brought into the processing space in the chamber 100 through the entrance and the substrate W may be taken out from the processing space in the chamber 100 . The doorway may be configured to be opened and closed by a separate driving device (not shown). The chamber 100 may be grounded, and an exhaust hole 102 may be formed at a lower portion thereof. Although not shown in detail, the exhaust hole 102 may be connected to the exhaust line 104 and an exhaust pump (not shown). Reaction by-products generated in the process and gas remaining in the inner space of the chamber 100 may be discharged to the outside through the exhaust hole 102 . Also, the inside of the chamber 100 may be decompressed to a predetermined pressure by the exhaust process.

A substrate support unit 200 for supporting the substrate W may be provided in the chamber 100 . The substrate support unit 200 may include an electrostatic chuck 220 for adsorbing and fixing the substrate W, and a base plate 210 supporting the electrostatic chuck 220 . The electrostatic chuck 220 may be made of a plate of a dielectric material such as alumina, and a chuck electrode 230 for generating an electrostatic force therein may be provided. When a voltage is applied to the chuck electrode 230 by the power source 232 , an electrostatic force may be generated so that the substrate W may be adsorbed and fixed to the electrostatic chuck 220 .

The base plate 210 is positioned under the electrostatic chuck 220 and may be made of a metal material such as aluminum. The base plate 210 may include a cooling unit 212 therein. The cooling unit 212 may include a refrigerant passage through which a cooling fluid flows, and may function as a cooling means for cooling the electrostatic chuck 220 . The refrigerant passage may be formed in the base plate 210 to serve as a circulation passage through which the cooling fluid circulates. The electrostatic chuck 220 may be cooled through circulation of the cooling fluid, and thus the substrate W supported by the electrostatic chuck 220 may be cooled to a desired temperature. Although not shown, by forming a heat transfer gas supply passage in the base plate 210 and the electrostatic chuck 220 and supplying the heat transfer gas to the rear surface of the substrate W, the cooling unit 212 and the substrate W via the heat transfer gas Heat transfer may be made between the substrates W to be cooled.

The gas supply unit 300 is configured to supply a process gas for an etching process into the chamber 100 , and may include a supply nozzle 302 connected to the gas supply unit 2 . The supply nozzle 302 may be formed on a sidewall of the chamber 100 . Although FIG. 2 shows that the gas supply unit is provided in the form of a supply nozzle, the present invention is not limited thereto. For example, a shower head formed to face the substrate and including a plurality of injection holes may be provided on the upper portion of the chamber 100 to inject gas into the chamber 100 .

The plasma generating unit 400 is configured to generate plasma in the processing space inside the chamber 100 . The plasma generating unit 400 may apply electric power to the gas supplied into the chamber 100 to be excited into a plasma state.

Plasma can be generated in a variety of ways. For example, an inductively coupled plasma (ICP) method, a capacitively coupled plasma (CCP) method, or a remote plasma (Remote Plasma) method may be used. Taking the inductively coupled plasma (ICP) apparatus of FIG. 2 as an example, the plasma generating unit 400 includes a plasma source 410 installed in a coil shape on the upper portion of the chamber 100 and one for applying power to the plasma source 410 . The above RF power source 420 may be included. The plasma source 410 and the RF power source 420 may be electrically connected, and a matching unit 430 may be provided between the plasma source 410 and the RF power source 420 .

The plasma source 410 may receive RF power from the RF power source 420 to induce a time-varying magnetic field in the chamber, and accordingly, the process gas supplied to the chamber 100 may be excited into plasma. That is, the plasma source 410 may induce an electromagnetic field in the chamber 100 by receiving RF power. Although not shown, the plasma generating unit 400 may further include an electromagnetic field adjusting unit for adjusting the electromagnetic field induced by the plasma source 410 .

For example, the plasma source 410 may include a planar coil having at least one winding. That is, the plasma source 410 may include a plurality of coils receiving RF power from different power sources.

For example, as shown in FIG. 2 , the plasma source 410 is located outside the upper part of the chamber 100 so as to surround the first coil 412 and the first coil 412 positioned inside the upper part of the chamber 100 . It may include a second coil 414 positioned. The RF power source 420 may include a first RF power source 421 connected to the first coil 412 and a second RF power source 422 connected to the second coil 414 . The first RF power source 421 may apply RF power to the first coil 412 , and the second RF power source 422 may apply RF power to the second coil 414 .

The first RF power source 421 and the second RF power source 422 may output RF power of different frequencies. The matching unit 430 is a device for matching the impedance of the RF power sources 421 and 422 with the impedance of the load, and includes a plurality of matching units to respectively correspond to the first RF power source 421 and the second RF power source 422 . circuit may be included. In addition to the first RF power source 421 and the second RF power source 422 , a third RF power source having another frequency may be provided. Alternatively, a separate bias power supply may be connected to the base plate 210 . Alternatively, both the first and second coils 412 and 414 may receive power from one RF power source.

Meanwhile, the structure of the plasma source 410 is not limited to the above-described embodiment. For example, the plasma source 410 may be configured as a single coil having at least one winding.

The gas supply unit 2 is configured to supply gas to the gas supply unit 300 , and may include an etching precursor 5 . For example, the gas supply unit 2 may include a canister 310 for storing the etching precursor 5 . The etching precursor 5 according to the present invention may exist in a liquid phase at room temperature. That is, it may be a material having a boiling point of 0° C. or higher at atmospheric pressure. The etching precursor 5 may be a material for etching the substrate W by reacting with the layer to be etched of the substrate W. For example, the layer to be etched may be a silicon oxide layer. In this case, the layer to be etched may be etched in a specific pattern such as a hole or a trench. To this end, a mask layer may be patterned on the layer to be etched. The mask layer may be a silicon nitride layer (Si3N4) or an amorphous carbon layer (ACL). In order to secure the etching selectivity, the etching rate by the etching precursor 5 may be large for the etched layer and small for the mask layer. The etching precursor 5 according to the embodiment of the present invention has a high boiling point and may be one of liquid fluorocarbon (CF) series, which is a compound of carbon and fluorine atoms. Alternatively, the etching precursor 5 according to an embodiment of the present invention may be one of a hydrofluorocarbon (HFC) series, which is a compound of carbon, fluorine, and hydrogen atoms.

Specifically, the etching precursor 5 according to the embodiment of the present invention is C ₆ F ₆ , C ₅ F ₁₀ , C ₅ F ₁₂ , C ₆ F ₁₀ , C ₆ F ₁₂ , C ₆ F ₁₄ , C ₇ F ₁₄ . , C ₇ F ₁₆ , and C ₈ F ₁₆ . or C ₃ H ₂ F ₆ , C ₄ H ₂ F ₆ , C ₄ H ₂ F ₈ , C ₄ H ₄ F ₆ , C ₅ HF ₉ , C ₅ H ₂ F ₈ , C ₅ HF ₇ , C ₅ H ₃ F ₇ , C ₆ HF ₁₃ , C ₆ H ₂ F ₁₂ , C ₆ H ₅ F ₉ , C ₆ H ₇ F ₇ , C ₆ H ₈ F ₆ , C ₆ H ₃ F ₉ , C ₆ H ₄ F ₈ , C ₆ H ₅ F ₇ .

Since the etching precursor 5 according to the embodiment of the present invention exists in a liquid phase at room temperature, it may be well adsorbed to the substrate.

During the process, the etching precursor 5 may be maintained in a liquid phase, and must be vaporized and supplied into the chamber 100 in the form of a gas for the etching process. Although a heating method can be used to vaporize the liquid etching precursor 5, the liquid etching precursor 5 is a very stable material, so it is not well dispersed. have. According to the unstable supply, an excessive amount of the precursor 5 unsuitable for atomic layer etching may be non-uniformly adsorbed to the substrate, thereby limiting the self-limited reaction. Accordingly, a phenomenon may occur in which the roughness of the substrate on which the process is completed becomes worse than that of the substrate before the process.

Accordingly, in order to vaporize the liquid etching precursor 5 and supply it to the chamber 100 , a carrier gas 51 and a vibrator applied to a humidifier may be used. As the carrier gas 51 , an inert gas such as nitrogen (N2), argon (Ar), or helium (He) may be used. The carrier gas 51 may be introduced into the canister 310 in which the etching precursor 5 is stored through the gas flow path 52 .

As shown in FIG. 3 , the canister 310 may include a vibrator 318 for supplying the liquid etching precursor 5 to the chamber 100 by vaporizing it. When the carrier gas 51 flows into the canister 310 , the canister 310 may drive the vibrator 318 to vaporize the liquid etching precursor 5 in a bubbling manner. The liquid-phase etching precursor 5 vaporized by the carrier gas 51 and the vibrator 318 may be delivered to the gas supply unit 300 through the gas flow path 312 . A mass flow controller (MFC) 314 and a valve 316 for controlling a gas flow rate may be installed in the gas flow path 312 . In addition, a temperature maintaining member (not shown) may be provided in the canister 310 to maintain the etching precursor 5 at a constant temperature. The temperature maintaining member may be a heater or a cooler. Meanwhile, as a method of vaporizing the etching precursor 5 in the liquid phase, a method of supplying to the chamber 100 by vaporizing by a heating method using a heating system in addition to a bubbling method using a carrier gas may be used.

Although it has been described in FIG. 3 that the vibrator 318 is provided inside the canister 310 , the vibrator 318 may be provided outside the canister 310 to vibrate the etching precursor 5 .

Meanwhile, one or more other processing gases 6 in addition to the etching precursor 5 may be supplied to the gas supply unit 300 . The processing gas 6 may be supplied to adjust an etch rate or an etch selectivity ratio. For example, the processing gas 6 may be an inert gas such as argon (Ar), helium (He), krypton (Kr), or xenon (Xe). Alternatively, the process gas 6 may be oxygen (O2) or hydrogen (H2). The processing gas 6 may be connected to the gas supply unit 300 through the gas flow path 62 . An MFC 63 and a valve 64 for controlling a gas flow rate may be installed in the gas flow path 62 .

The chamber heating unit 500 may heat the chamber 100 wall by including a heat source in a configuration for heating the chamber 100 wall. The chamber heating unit 500 may use electromagnetic waves to heat the walls of the chamber 100 . For example, a light source such as an IR lamp, a UV lamp, a halogen lamp, an LED, an incandescent lamp, or a fluorescent lamp may be used as the heat source. It is possible to prevent contamination inside the chamber by the precursor. The chamber heating unit 500 may be provided to be in contact with the outer wall of the chamber 100 to directly heat the wall of the chamber 100 . Alternatively, the chamber 100 may be supported by a separate support member spaced apart from the chamber 100 by a predetermined distance to transmit radiant heat to the outer wall of the chamber 100 .

Since the liquid fluorocarbon precursor exists as a liquid at room temperature, it is not only used on the substrate W but also on the inner wall of the chamber 100, the electrostatic chuck 220, the supply nozzle 300, and the internal components of the chamber 100, such as the gas flow path 312. can be adsorbed. The liquid precursor adsorbed to the internal components of the chamber 100 may cause contamination of the chamber and may be polymerized by plasma. Contamination of the chamber can affect the reliability of the process. Also, when the precursor is adsorbed to the electrostatic chuck 220 made of a dielectric and polymerized, it may be difficult to stably transmit power to the electrostatic chuck 220 by the polymer. In addition, the DC voltage induced to the substrate is changed according to the thickness of the polymer and the degree of contamination, so that the ion energy distribution is changed, and as the impedance of the chamber is changed, the uncertainty in the process may increase. That is, the reliability of the process may be greatly affected.

Accordingly, in order to prevent the liquid precursor from being adsorbed to a region other than the substrate, the chamber heating unit 500 may be provided to heat the wall of the chamber 100 . At this time, the temperature of the wall of the chamber 100 is preferably heated to a temperature higher than the boiling point of the liquid precursor. As an example, the walls of the chamber 100 may be heated to a temperature of one of 30°C to 150°C.

Hereinafter, an atomic layer etching method according to an embodiment of the present invention will be described with reference to FIGS. 4 and 5 .

4 is a flowchart illustrating an atomic layer etching method according to an embodiment of the present invention, and FIG. 5 is a diagram illustrating an atomic layer etching principle.

Referring to FIG. 4 , the atomic layer etching method according to an embodiment of the present invention includes an adsorption process for adsorbing a process gas to a substrate, and a desorption process for generating plasma to desorb an atomic layer. process, and may include a purge process in which a purge gas is injected into the chamber 100 between the adsorption process and the desorption process and after the desorption process is completed to discharge the material inside the chamber. Whenever one cycle consisting of an adsorption process → a purge process → a desorption process → a purge process is performed, atoms in a layer unit can be removed from the substrate.

Specifically, the atomic layer etching method according to an embodiment of the present invention includes a substrate preparation step (S10), an adsorption step (S20), a first purge step (S30), a desorption step (S40), a second purge step (S50), It may include a process termination and substrate unloading step (S60).

The substrate preparation step S10 may include loading the substrate W into the chamber 100 and seating the loaded substrate W on the substrate support unit 200 . When the substrate W is seated, a voltage is applied to the chuck electrode 230 by the power supply 232 , so that the substrate W may be electrostatically adsorbed to the electrostatic chuck 220 . When the substrate is adsorbed, the internal pressure of the chamber 100 may be adjusted to a predetermined vacuum pressure. The pressure inside the chamber 100 may be differently controlled according to process steps.

The adsorption step ( S20 ) may include supplying an etching gas into the chamber 100 . The etching gas may be the canister 310 including the vibrator 318 and the etching precursor 5 conveyed by being vaporized in a bubbling manner by the carrier gas 51 . The etching precursor 5 used in the embodiment of the present invention is a material having a boiling point of 0° C. or higher at atmospheric pressure, and is a fluorocarbon (CF)-based compound of carbon and fluorine, or hydrofluorocarbon, a compound of fluorine and hydrogen. It may be one of the hydrofluorocarbon (HFC) systems. As shown in FIG. 5 , the liquid-phase etching precursor 5 supplied to the substrate W by the gas supply unit 200 may be adsorbed on the surface atomic layer of the substrate W.

In this case, by controlling the cooling unit 212 so that the temperature of the substrate has a difference from the temperature inside the chamber 100 , the etching precursor 5 may be induced to be adsorbed onto the substrate. In addition, the amount and uniformity of the precursor adsorbed to the surface of the substrate may be controlled by controlling the temperature of the substrate according to the characteristics of the etching precursor 5 . Alternatively, although not shown, an electromagnetic wave source capable of supplying an electromagnetic wave to the substrate may be provided to activate the precursor by supplying the electromagnetic wave to the substrate to control the amount of the precursor adsorbed to the substrate surface.

For example, in the adsorption step ( S20 ), the C5F8 gas may be supplied into the chamber 100 having a vacuum pressure of 3 mTorr for 5 seconds.

In the first purge step ( S30 ), materials including the process gas remaining in the chamber 100 without being adsorbed on the surface of the substrate W in the adsorption step ( S20 ) are removed from the chamber 100 through the exhaust hole 102 . It can be removed by discharging. The first purge step S30 may be performed using an inert gas such as argon (Ar), helium (He), krypton (Kr), or xenon (Xe).

In particular, when the precursor 5 is excessively supplied in the adsorption step S20 , the execution time of the first purge step S30 is increased to adsorb on the substrate surface among the etching precursors 5 supplied into the chamber 100 . Materials such as the remaining precursors except for the precursor 5 of one layer or the desired number of N layers may be discharged to the outside of the chamber 100 .

For example, the first purge step ( S30 ) may be performed for a sufficient time period for all other precursors except for the precursor 5 of the N layer adsorbed on the substrate surface to be discharged to the outside of the chamber 100 . Alternatively, the first purge step ( S30 ) may include a plasma generation step of generating a weak plasma by the supplied inert gas. By forming a weak plasma, the reactivity is increased and materials such as the remaining precursors other than the precursor 5 of the N layer adsorbed on the substrate surface among the etching precursors 5 supplied into the chamber 100 in a relatively short time are transferred to the chamber 100 ) can be discharged outside. That is, according to the first purge step S30 , all materials such as the remaining precursors except for the precursor 5 adsorbed on the substrate surface among the etching precursors 5 supplied into the chamber 100 are discharged to the outside of the chamber 100 . can do it As described above, according to the first purge step ( S30 ), since the thickness of the precursor adsorbed on the substrate surface can be uniformly controlled, the surface roughness of the substrate on which the etching process is completed can be improved.

For example, in the first purge step S30 , argon (Ar) gas may be supplied into the chamber 100 having a vacuum pressure of 10 mTorr for 1 minute. Alternatively, argon (Ar) gas may be supplied into the chamber 100 having a vacuum pressure of 5 mTorr to generate weak plasma for 5 seconds.

The desorption step S40 may include a step of supplying the processing gas 6 into the chamber 100 and a plasma generation step of generating plasma by the plasma generating unit 400 . The processing gas 6 may be one of an inert gas such as argon (Ar), helium (He), krypton (Kr), or xenon (Xe). RF power may be provided by an RF power source 420 coupled to the plasma source 410 for plasma generation. The RF power source 420 may include two or more RF power sources 421 and 422 . Also, a bias voltage may be applied to the substrate through the base plate 210 .

As shown in FIG. 5 , in the desorption step S40 , the processing gas 6 is ionized by plasma and incident in the direction of the substrate W, so that the atomic layer of the substrate W combined with the etching precursor 5 is the substrate. It can separate from (W) and fall off. According to the desorption step ( S40 ), the substrate may be etched in a predetermined pattern. For this, a mask having a pattern formed thereon may be provided on the substrate.

For example, in the desorption step ( S40 ), power of 200 W is applied to the plasma source 410 , a voltage of -7 V may be applied to the base plate 410 , and the vacuum pressure is 5 mTorr to the inside of the chamber 100 . Argon (Ar) gas may be supplied to generate argon plasma for 20 seconds.

Subsequently, the materials of the atomic layer separated by the second purge step S50 may be discharged to the outside of the chamber 100 through the exhaust hole 102 . For example, in the second purge step ( S50 ), argon (Ar) gas may be supplied into the chamber 100 having a vacuum pressure of 5 mTorr for 10 seconds.

Each time the process from the adsorption step ( S20 ) to the desorption step ( S40 ) is performed once, one atomic layer may be etched. Accordingly, by controlling the number of repetitions of the process from the adsorption step ( S20 ) to the desorption step ( S40 ), a desired number of atomic layers can be etched.

When the desired number of atomic layers is etched, the step ( S60 ) of terminating the process and unloading the substrate may be performed. The unloading of the substrate may be a step in which the substrate transport robot, which has entered from the transport module arranged to communicate with the chamber 100 , grips the substrate W and carries it out.

Atomic layer etching processing apparatus according to an embodiment of the present invention uses a high boiling point liquid fluorocarbon or liquid hydrofluorocarbon as a precursor. The liquid precursor may be applied as an etching gas and at the same time react with the silicon wafer to form a passivation on a sidewall of a layer to be etched (eg, a trench). Therefore, the high aspect ratio, high selectivity, and high directionality that could be obtained by second-generation atomic layer etching using cryogenic temperatures can be obtained at a relatively high temperature.

On the other hand, since the etching precursor 5 used in the embodiment of the present invention is a fluorocarbon or hydrofluorocarbon precursor that exists in a liquid phase at room temperature, it may be easily adsorbed to the substrate. However, for the same reason, it may be adsorbed not only to the substrate W but also to internal components of the chamber 100 , such as the inner wall of the chamber 100 , the electrostatic chuck 220 , the supply nozzle 300 , and the gas flow path 312 . The liquid precursor adsorbed to the internal components of the chamber 100 may cause contamination of the chamber and may be polymerized by plasma. Contamination of the chamber can affect the reliability of the process. Also, when the precursor is adsorbed to the electrostatic chuck 220 made of a dielectric and polymerized, it may be difficult to stably transmit power to the electrostatic chuck 220 .

To prevent this, the etching processing method according to the embodiment of the present invention may include a chamber heating step. In the chamber heating step, the temperature of the chamber wall may be heated to a temperature higher than the boiling point of the etching precursor 5 . The chamber heating step may be performed by the chamber heating unit 500 , and adsorption of the precursor 5 to the chamber internal components may be prevented by chamber wall heating. The chamber heating step may be continuously performed during the entire period of the etching process.

6 is a view for comparing the general atomic layer etching and the atomic layer etching using a liquid precursor according to an embodiment of the present invention.

6(a) shows a conventional atomic layer etching process, FIG. 6(b) shows an atomic layer etching process using a liquid precursor, and FIG. 6(c) shows an atomic layer etching process optimized according to an embodiment of the present invention. The atomic layer etching process using a liquid fluorocarbon precursor is shown.

As shown in FIG. 6( a ) , the general atomic layer etching process includes an adsorption process for adsorbing a process gas to the substrate, and desorption of an atomic layer by generating plasma, as described above. It includes a desorption process for etching the , and between the adsorption process and the desorption process and after the desorption process is completed, a purge gas is injected into the chamber 100 to discharge the material inside the chamber. Purge process may be included. The adsorption process is a step in which the surface layer of the object to be etched can be easily removed in the desorption process, and is also referred to as a modification step. Atomic layer etching can remove one atomic layer from the substrate and reach a desired depth whenever one cycle consisting of adsorption process → purge process → desorption process → purge process is performed. The cycle can be repeated until In addition, since the atomic layer etching has a self-limited characteristic in which the reaction is automatically stopped when the surface is saturated, it has the advantage of accurately removing as many layers as desired.

However, as described above, general atomic layer etching may cause contamination and damage to the substrate, and may be inefficient in terms of cost and time. In order to solve this problem, the present invention proposes atomic layer etching using a liquid precursor existing in a liquid phase at room temperature. According to the liquid precursor, there is an advantage in that the cryogenic characteristics by the second-generation atomic layer etching can be realized at a temperature close to room temperature.

However, since the liquid precursor is a very stable material, it is not well dispersed, so that when vaporization by heating is used, a problem may occur in the stable supply of the precursor. In addition, as shown in the purge step of FIG. 6(b), which is not suitable for atomic layer etching, an excessive amount of the precursor 5 is non-uniformly adsorbed to the substrate, thereby limiting the self-limited reaction. can occur Accordingly, as shown in the desorption step of FIG. 6( b ), some surfaces of the substrate may be removed more than the desired number of layers. As a result, a phenomenon may occur in which the roughness of the substrate on which the process is completed becomes worse than that of the substrate before the process.

Therefore, in the present invention, the liquid precursor is supplied by vaporizing it in a bubbling manner using a vibrator, controlling the temperature of the substrate in the adsorption step, and controlling the execution time or gas supply method of the first purge step. A method for optimizing the atomic layer etching method was also presented. Specifically, in the adsorption step, in order to stably supply the liquid precursor in a stable state, it is vaporized and supplied in a bubbling method using a vibrator, and the temperature of the substrate is controlled using a cooling unit so that the precursor can be adsorbed to the surface of the substrate. In the first purge step, the process time is increased until all of the liquid precursor is removed except for the N layer adsorbed on the substrate surface, or an inert gas (eg Ar, Xe, Kr, etc.) is supplied by generating a weak plasma. The thickness of the precursor adsorbed to the substrate was uniformly controlled by applying a method such as the above method. As a result, as shown in the last step of FIG. 6(c) , a uniform and smooth substrate surface can be realized by the optimized liquid-phase precursor atomic layer etching. In addition, it is possible to prevent a problem of adsorption of the precursor in the area outside the substrate, which may be caused by using the liquid precursor by heating the outer wall of the chamber during the entire process.

As described above, according to the atomic layer etching method according to the embodiment of the present invention, uniform and precise atomic layer etching, which is an advantage of cryogenic etching, can be implemented even at a temperature close to room temperature.

Those skilled in the art to which the present invention pertains should understand that the present invention may be embodied in other specific forms without changing the technical spirit or essential characteristics thereof, so the embodiments described above are illustrative in all respects and not restrictive. only do

The scope of the present invention is indicated by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. .

100: chamber
200: substrate support unit
300: gas supply unit
400: plasma generating unit
500: chamber heating unit

Claims (16)

supplying an etching precursor maintained in a liquid phase to a chamber by vaporizing;
an adsorption step in which the etching precursor is adsorbed to the substrate surface;
a first purge step of purging the inside of the chamber by supplying an inert gas into the chamber after the adsorption step;
a desorption step of etching the substrate by generating plasma in the chamber;
a second purge step of purging the inside of the chamber by supplying an inert gas into the chamber after the desorption step;
Atomic layer etching method comprising a.
According to claim 1,
The etch precursor is a material having a boiling point of 0° C. or higher at atmospheric pressure, and is one of fluorocarbon (CF)-based compounds of carbon and fluorine.
According to claim 1,
The etching precursor is a material having a boiling point of 0° C. or higher at atmospheric pressure, and an atomic layer etching method, characterized in that it is one of a hydrofluorocarbon (HCF) system, which is a compound of carbon, fluorine, and hydrogen.
According to claim 1,
An atomic layer etching method, characterized in that the etching precursor is vaporized in a bubbling manner by a vibrator.
According to claim 1,
The first purge step is
Atomic layer etching method, characterized in that for discharging the remaining precursors except for the precursor adsorbed on the surface of the substrate to the outside of the chamber.
According to claim 1,
The first purge step is
Atomic layer etching method comprising the step of generating a plasma by supplying a weaker power than the desorption step.
According to claim 1,
The adsorption step is an atomic layer etching method comprising the step of controlling the temperature of the substrate.
According to claim 1,
Atomic layer etching method, characterized in that it further comprises a chamber wall heating step of heating the temperature of the chamber wall to a temperature higher than the boiling point of the etching precursor.
The atomic layer etching method of claim 8, wherein the heating of the chamber wall is performed at least during the adsorption step.
10. The method of claim 9,
The atomic layer etching method, characterized in that the chamber wall heating step is performed by electromagnetic waves.
11. The method of claim 10,
The chamber wall heating step is an atomic layer etching method, characterized in that performed by any one light source of IR lamp, UV lamp, halogen lamp, LED, incandescent lamp, fluorescent lamp.
a chamber providing a substrate processing space;
a support unit for supporting the substrate;
and a gas supply unit that vaporizes the etching precursor maintained in a liquid phase and supplies it into the chamber,
The gas supply unit atomic layer etching apparatus including a canister for storing the precursor in the liquid phase.
13. The method of claim 12,
The canister includes a vibrator for vibrating the liquid precursor, and vaporizing the liquid precursor in a bubbling manner using the vibrator.
13. The method of claim 12,
The etching precursor is a material having a boiling point of 0° C. or higher at atmospheric pressure, and is one of a fluorocarbon (CF)-based compound of carbon and fluorine or a hydrofluorocarbon (HFC)-based compound of carbon, fluorine, and hydrogen. Atomic layer etching apparatus, characterized in that.
13. The method of claim 12,
Atomic layer etching apparatus according to claim 1, further comprising a chamber heating unit for heating the chamber wall.
16. The method of claim 15,
The chamber heating unit is an atomic layer etching apparatus, characterized in that for heating the wall surface of the chamber to a temperature higher than the boiling point of the etching precursor.

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