Atomic layer etching method and device

Abstract

An atomic layer etching method of one embodiment may include: a step of providing a substrate on which an etching object material is formed; a modification step of controlling the substrate at a first temperature and supplying a modifying gas to modify and remove a surface layer of the object material; and an etching step of controlling the substrate at a second temperature different from the first temperature and supplying an etching gas to remove the modified surface layer.

Description

Technical Field

[0001] The present invention relates to a semiconductor manufacturing method, and more particularly to an atomic layer etching method and device. Background Art

[0002] In the semiconductor device manufacturing process, the etching process is a process of selectively removing target materials in order to form a desired structure.

[0003] Atomic layer etching (ALE) is a process for removing a target material by a target amount (thickness).

[0004] The ALE process may be referred to as an etching process in which a step of modifying a surface of a target material and a step of removing the modified surface are repeatedly performed in a predetermined cycle period.

[0005] The ALE process can achieve atomic-level control over the removal of target materials, and is therefore being actively used in the manufacturing process of increasingly miniaturized semiconductor devices.

[0006] The current ALE process performs the modification step and the removal step while maintaining a state of heating the substrate at a high temperature.

[0007] According to this, a thermal shock is applied to the target material to change the crystal structure and the electrical characteristics can be changed. Summary of the invention

[0008] Means of solving the problem

[0009] An atomic layer etching method according to an embodiment of the present invention may include: a step of providing a substrate having an etching object material formed thereon; a modification step of controlling the substrate at a first temperature and supplying a modification gas to modify a surface layer of the removal object material; and an etching step of controlling the substrate at a second temperature different from the first temperature and supplying an etching gas to remove the modified surface layer.

[0010] An atomic layer etching device according to an embodiment of the present invention includes: a chamber, which forms a first processing space and a second processing space; a gas supply device, which is used to spray a process gas into the interior of the chamber; a plasma generating part, which is activated in a plasma environment, and free-radicalizes the process gas supplied from the gas supply part and supplies it to the interior of the chamber; a base, which is arranged to face the gas supply device and has at least one substrate placed on the upper part; a first temperature control tool, which is configured to surround the upper end of the inner wall of the chamber to form the first processing space; a second temperature control tool, which is configured to surround the lower end of the inner wall of the chamber to form the second processing space; and a controller, which controls the first temperature control tool to control the substrate loaded in the first processing space at the first temperature, and controls the second temperature control tool to control the substrate loaded in the second processing space at the second temperature; wherein, the surface layer of the etching object material is modified in any one of the first processing space and the second processing space, and the modified surface layer is etched in the other space. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A conceptual diagram for illustrating an atomic layer etching method according to an embodiment.

[0012] Figure 2 is a flow chart for describing an atomic layer etching method according to an embodiment.

[0013] Figure 3 FIG. 4 is a graph for illustrating a 1-cycle period of an ALE process according to an embodiment.

[0014] Figure 4 It is a structural diagram of an atomic layer etching device according to an embodiment.

[0015] Figure 5 It is a structural diagram of an atomic layer etching device according to an embodiment. DETAILED DESCRIPTION

[0016] Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0017] Figure 1 A conceptual diagram for illustrating an atomic layer etching method according to an embodiment.

[0018] Reference Figure 1 A substrate formed with a target material 1000 for performing an ALE process may be provided to an atomic layer etching apparatus.

[0019] Then, a modifying gas is supplied into the atomic layer etching apparatus to modify the surface layer 1100 of the target material 1000. The modifying gas is determined according to the type of the target material 1000.

[0020] An etching gas may be supplied after modifying the surface layer 1100. Accordingly, the modified surface layer 1100 of the target material 1000 may be removed.

[0021] Figure 2 is a flow chart for illustrating an atomic layer etching method according to an embodiment; Figure 3 FIG. 4 is a graph for illustrating a 1-cycle period of an ALE process according to an embodiment.

[0022] Reference Figure 2 After the substrate to be processed with the target material formed thereon is loaded into the chamber, a pretreatment process (S101) may be performed. The pretreatment process may be a process of injecting a gas selected from hydrogen or an inert gas into the chamber by radicalizing the gas. In one embodiment, the target material may be selected from a metal oxide film group including Al2O3, HfO2, and ZrO2, but is not limited thereto.

[0023] Then, if Figure 2 and Figure 3 As shown, the temperature of the substrate may be controlled to be at a first temperature (S103). The first temperature may be set to a temperature that can provide a minimum energy capable of modifying the surface layer of the target material.

[0024] If the substrate is controlled at the first temperature, a modified gas is supplied to modify the surface layer (S105). The modified gas is supplied after being radicalized by a plasma generator. The plasma generator can be selected from a direct plasma generator, a remote plasma generator, or a microwave plasma generator. At the same time, the remote plasma generator can use a CCP (Capacitor coupled plasma) method, an ICP (Inductively Coupled Plasma) method, etc.

[0025] In one embodiment, the modifying gas may be selected from the group consisting of NF3, F2, CHF3, OF2, etc.

[0026] As the modifying gas is supplied, the physical properties of the surface layer of the target material become physical properties that can be removed in the subsequent removal step.

[0027] In one embodiment, when the target material is Al2O3 and the modifying gas is one of NF3, F2, CHF3, and OF2, the physical properties of the Al2O3 surface layer are changed from Al2O3 to AlF after modification.

[0028] After the surface layer is modified, a first purge may be performed using an inert gas such as argon (Ar) (S107). The modified gas remaining on the substrate surface is removed by the first purge. In one embodiment, the purge gas may be continuously supplied from the modified gas supply step S105, but is not limited thereto.

[0029] Next, the temperature of the substrate may be controlled to a second temperature (S109). The second temperature may be set to a temperature that may cause a ligand exchange reaction between the subsequently supplied etching gas and the modified surface layer.

[0030] In one embodiment, the second temperature may be 50-100° C. higher than the first temperature.

[0031] When the temperature of the substrate rises to the second temperature, an etching gas is supplied ( S111 ). The etching gas may be supplied by vaporizing a metal-containing precursor and is determined according to the type of the target material.

[0032] In one embodiment, when the target material is Al2O3, HfO2, or ZrO2, the metal-containing precursor may be selected from metal organic precursors such as TMA (Trimethyl Aluminum), DMA (Dimethyl Aluminum chloride), or ACAC (Acetylacetonate).

[0033] Then, the reaction byproducts and residual gas can be removed by a secondary purge step S113 using an inert gas such as argon (Ar). In one embodiment, the purge gas can be continuously supplied while the etching gas is supplied.

[0034] The temperature control step S103 from the first temperature to the secondary purge step S113 is a 1-cycle period of the ALE process of the present invention. The total number of cycles (N=L / M) can be determined according to the removal object thickness L of the target material and the thickness M removed through the 1-cycle period.

[0035] After the surface layer is removed, the modified material remaining on the substrate surface may be removed by a post-treatment process (S115). In one embodiment, the post-treatment process may be a process of injecting a gas selected from hydrogen or an inert gas into the chamber in a radicalized state.

[0036] ZrO2 films having a high dielectric constant are used as dielectric films of semiconductor devices and have temperature-sensitive properties.

[0037] In the past, the ALE process was performed at the same high temperature for both the modification and removal processes.

[0038] Therefore, if a radicalized reforming gas is injected into the ZrO2 film at a temperature above 200°C, the crystal structure changes due to thermal stress caused by the surface reaction, and protrusions such as hillocks appear on the surface of the film, and the electrical characteristics change.

[0039] To prevent this phenomenon, if the ALE process is performed at a low temperature of about 100°C, a ligand exchange reaction will not occur through the chemical reaction of the etching gas, so etching is impossible.

[0040] According to the present invention, in order to supply the minimum energy capable of modifying the film surface, modification is performed at a low temperature, and the temperature is increased before the etching gas is injected to cause a ligand exchange reaction, thereby enabling the target film to be removed at a target thickness.

[0041] In another embodiment of the present invention, the target material may be selected from the group consisting of metal films including TiN and Ta.

[0042] like Figure 2 and Figure 3 As shown, in order to remove such a metal film by an atomic layer etching method, the temperature of the substrate may be controlled to a first temperature (S103). The first temperature may be set to a temperature that can provide a minimum energy capable of modifying the surface layer of the target material.

[0043] If the substrate is controlled at the first temperature, a modifying gas is supplied to modify the surface layer (S105). The modifying gas is supplied by vaporizing hydrogen peroxide using an oxygen-containing gas, such as O3 or H2O, as a carrier gas through corona discharge.

[0044] As the modifying gas is supplied, the physical properties of the surface layer of the target material are changed to physical properties that can be removed in the subsequent removal step.

[0045] When the surface material is TiN and the modified gas is one of O3 or H2O2, the surface layer of TiN after modification is changed to TiO2 by the following chemical formula:

[0046] TiN(s)+3 / 2O2(g)→TiO2(s)+NO(g);

[0047] TiN(s)+3H2O2(g)→TiO2(s)+NO(g)+3H2O(g).

[0048] After modifying the surface layer, a first purge (S107) may be performed using an inert gas such as argon (Ar). The modifying gas remaining on the substrate surface is removed by the first purge. In one embodiment, the purge gas may be continuously supplied from the modifying gas supply step S105, but is not limited thereto.

[0049] Next, the temperature of the substrate may be controlled to a second temperature (S109). The second temperature may be set to a temperature at which the subsequently supplied etching gas and the modified surface layer may react.

[0050] In one embodiment, the second temperature may be 50-100° C. lower than the first temperature.

[0051] If the temperature of the substrate drops to the second temperature, etching gas is supplied (S111). The etching gas can be supplied after being radicalized by a plasma generator. The plasma generator can be selected from a direct plasma generator, a remote plasma generator, or a microwave plasma generator. At the same time, the remote plasma generator can use a CCP (Capacitor coupled plasma) method, an ICP (Inductively Coupled Plasma) method, etc.

[0052] In one embodiment, the deformed surface layer TiO2 of the TiN film as the target material layer may be removed by using one of NF3, F2, CHF3, OF2, and CF4 as an etching gas.

[0053] The characteristics of the reaction of TiN film and TiO2 film with fluorine-containing gas are as follows:

[0054] TiN(s)+3HF(g)→TiF3(s)+NH3(g);

[0055] TiO2(s)+4HF(g)→TiF4(g)+2H2O(g).

[0056] TiF3 generated by fluorination of TiN film is solid and remains on the surface without being removed due to its non-volatile nature. In contrast, TiF4 generated by fluorination of TiO2 film is gaseous and therefore volatile, enabling ALE reaction.

[0057] Therefore, in order to provide the minimum energy capable of modifying the film surface of the target material, modification is performed at a first temperature, and the temperature is changed to a second temperature before the etching gas is injected to induce a ligand exchange reaction, thereby enabling the target film to be removed with a target thickness.

[0058] Next, a secondary purge step S113 using an inert gas such as argon (Ar) may be performed to remove the reaction byproducts and residual gas. In one embodiment, the purge gas may be continuously supplied while the etching gas is supplied.

[0059] After the surface layer is removed, the modified material remaining on the substrate surface can be removed by a post-treatment process (S115). In one embodiment, the post-treatment process can be a process of injecting a gas selected from hydrogen or an inert gas into the chamber after radicalization.

[0060] As described above, the ALE process of the TiN film repeatedly uses oxygen-containing gas (O3 or H2O2) as a modifying gas to oxidize the surface and convert it into TiO2, and then injects a radicalized etching gas. At this time, in order to oxidize the TiN film surface, a temperature of more than 200°C is required. On the contrary, in the case of a radicalized etching gas, a temperature of less than 150°C is required to selectively remove the TiO2 film.

[0061] According to this, the atomic layer etching process can be performed to achieve a desired thickness while controlling the temperatures of the modifying step and the removing step to maintain the characteristics of the removal target film.

[0062] Figure 4 It is a structural diagram of an atomic layer etching device according to an embodiment.

[0063] Reference Figure 4 The atomic layer etching device 10 may include: a chamber 100 , a gas supply unit 200 , a plasma generating unit 300 and a controller 400 .

[0064] The chamber 100 may include: a main body 110 with an open top; and a top cover 120 disposed on the outer periphery of the upper end of the main body 110. The inner space of the top cover 120 may be closed by a shower head 121. An insulating ring R is disposed between the shower head 121 and the top cover 120 to electrically insulate the chamber 100 from the shower head 121.

[0065] The inner spaces 101 and 103 of the chamber 100 may be spaces for processing the substrate W, such as a deposition process. A door G for entering and exiting the substrate W is disposed at a designated position on the side of the body 110. The support shaft 140 of the base 130 on which the substrate W is placed passes through the bottom surface of the body 110 and can be inserted into the chamber 100.

[0066] The susceptor 130 as a whole has a flat plate shape to place at least one substrate W thereon, and faces the gas supply device 120 and can be arranged in a horizontal direction. The support shaft 140 can be configured to be vertically coupled to the rear of the susceptor 130 and connected to a driving unit (not shown) outside the chamber 100 to lift and / or rotate the susceptor 130.

[0067] A heater 132 is disposed inside the susceptor 130 to adjust the temperature of the substrate W placed thereon.

[0068] The interior of the chamber 100 should generally be in a vacuum environment, and therefore an exhaust port connected to the pump 160 may be formed at a designated position of the main body 110 , such as a side surface of the lower portion.

[0069] The gas supply device 120 may be disposed on the upper portion of the body 110 facing the base 130. The gas supply device 120 may inject various process gases supplied from the gas supply unit 200 into the chamber 100. The gas supply device 120 may be a shower type, a jet type, a nozzle type, or other gas supply devices.

[0070] The gas supply unit 200 may be configured to supply a modifying gas, an etching gas, a purge gas, etc. to the gas supply device 120 through the plasma generating unit 300 .

[0071] When plasma power is applied to the plasma generating unit 300 , the plasma generating unit 300 is activated in a plasma environment, and the process gas supplied from the gas supply unit 200 can be converted into radicals.

[0072] The plasma generating unit 300 can be selected from a direct plasma generating device, a remote plasma generating device or a microwave plasma generating device. Meanwhile, the remote plasma generating device can use a CCP (capacitor coupled plasma) method, an ICP (inductively coupled plasma) method or the like.

[0073] The controller 400 is configured to control the overall operation of the atomic layer etching apparatus 10. In one embodiment, the controller 400 controls the operation of the chamber 100, the gas supply unit 200, and the plasma generating unit 300, and can set control parameters for depositing thin films through an operator interface. Although not shown, the controller 400 may include a central processing unit, a memory, an input / output interface, and the like.

[0074] The atomic layer etching apparatus 10 of one embodiment of the present invention may further include: a first temperature control tool 153 for controlling the first processing space 101 at a first temperature; and a second temperature control tool 155 for controlling the second processing space 103 at a second temperature.

[0075] The first temperature control tool 153 is configured to surround the upper end of the inner wall of the chamber 100 to form the first processing space 101. The second temperature control tool 155 is configured to surround the lower end of the inner wall of the chamber 100 to form the second processing space 103.

[0076] The first temperature control tool 153 and the second temperature control tool 155 may be isolated from each other by the insulating member 151 .

[0077] In one embodiment, during the modification process, the susceptor 130 is raised to the first processing space 101 by the support shaft 140, and the temperature of the substrate W can be controlled at the first temperature by controlling the first temperature control tool 153 by the controller 400. During the removal process, the susceptor 130 is lowered to the second processing space 103 by the support shaft 140, and the temperature of the substrate W can be controlled at the second temperature by controlling the second temperature control tool 155 by the controller 400.

[0078] However, the present invention is not limited thereto, and of course the substrate W may be controlled at the second temperature in the first processing space 101 and at the first temperature in the second processing space 103 .

[0079] The temperature of the substrate W may be changed by the first and second temperature control tools 153 and 155 while the substrate W is raised and lowered during the repeated N-cycle period of the ALE process for the modifying step and the removing step.

[0080] Figure 5 It is a structural diagram of an atomic layer etching device according to an embodiment.

[0081] Reference Figure 5 In one embodiment, an atomic layer etching device 50 may include a first processing device 510 and a second processing device 520 .

[0082] The first processing device 510 and the second processing device 520 actually have the same structure. Figure 5 Only the first processing device 510 is shown in detail.

[0083] The first and second processing apparatuses 510 and 520 may include a chamber 100 - 1 , a gas supply unit 200 , a plasma generating unit 300 , and a controller 400 , respectively.

[0084] Chamber 100-1 may be in Figure 4 In the illustrated chamber 100 , the structures of the first temperature control means 153 , the second temperature control means 155 , and the insulating member 151 are omitted.

[0085] In one embodiment, the substrate W loaded in the first processing apparatus 510 may be controlled at the first temperature or the second temperature by the heater 132 , and the substrate W loaded in the second processing apparatus 520 may be controlled at the second temperature or the first temperature by the heater 132 .

[0086] In the modification step of the ALE process, for example, the substrate W is loaded in any one of the first processing device 510 and the second processing device 520 and is controlled at a first temperature. In the subsequent removal step, the substrate W is loaded in a device different from the modification step and is controlled at a second temperature.

[0087] An atomic layer etching apparatus according to an embodiment of the present invention may utilize a susceptor having a substrate supporting portion placement groove in which a plurality of (eg, more than four) substrate supporting portions are disposed.

[0088] The multiple substrate supporting parts can be vacuum suction cups or electrostatic suction cups for adsorbing and fixing the supported substrates, and can include multiple lifting pins, which can lift and space the substrates supported by the substrate supporting surface upward when transporting the substrates.

[0089] The substrate transporting unit may have various structures as a structure for rotationally transporting a substrate from one substrate supporting unit to another substrate supporting unit among the plurality of substrate supporting units.

[0090] The substrate transporting part may include: a plurality of substrate placement blades, the number of which corresponds to the number of substrate supporting parts, and a placement area for placing the substrates is formed on the blade combining body part, which is radially combined with the plurality of substrate placement blades; a rotating support shaft, which is combined with the blade combining body part to support the blade combining body part, and can rotate around a rotation axis perpendicular to the ground.

[0091] The plurality of substrate supporting parts are arranged at equal intervals along the periphery of the blade coupling main body of the substrate conveying part with the blade coupling main body as the center.

[0092] The plurality of substrate placement blades may include a placement area that enters between the substrate lifted upward by the lifting pins of the substrate supporting portion and the substrate supporting portion to support the substrate.

[0093] At this time, the plurality of substrate placement blades may be formed in a shape that avoids interference with the plurality of lift pins when entering a space between the substrate supported by the lift pins and the substrate supporting portion.

[0094] The blade-combined main body is rotated by the rotating support shaft with the rotating shaft perpendicular to the ground as the center, and a plurality of substrate placement blades can be rotated and moved from one substrate supporting part to another substrate supporting part.

[0095] Each of the plurality of substrate supporting parts may be provided with a heater therein.

[0096] During the ALE process, the ALE process can be performed while the substrate is placed on each substrate support. In particular, the modification process and the removal process can be performed in different substrate supports. The substrate support performing the modification process is controlled at a first temperature by a heater, and the substrate support performing the removal process can be controlled at a second temperature by a heater.

[0097] The substrate that has completed the modification process in a certain substrate supporting part is moved to another substrate supporting part through the substrate transporting part to perform the removal process.

[0098] Use in Figure 4 or Figure 5 The ALE process can be performed by changing the substrate temperature in the modification step and the removal step of the atomic layer etching apparatus shown or the above-mentioned pedestal. Accordingly, the surface layer can be modified without changing the crystal structure or electrical properties of the target material, and the ligand exchange reaction between the modified surface layer and the etching gas can be removed.

[0099] As described above, those skilled in the art to which the present invention belongs may understand that the present invention can be implemented in other specific forms without changing the technical ideas or essential features. Therefore, it should be understood that the above-mentioned embodiments are exemplary in all aspects and not restrictive. The scope of the present invention should be interpreted as being represented by the scope of the claims rather than the above-mentioned detailed description, and all changes or variant forms derived from the meaning, scope and equivalent concepts of the claims are included in the scope of the present invention.

Claims

1. An atomic layer etching method, performing atomic layer etching in a chamber having a first processing space and a second processing space, comprising: providing a substrate having an etching target material formed thereon to a susceptor located between the first processing space and the second processing space in the chamber; a modification step, wherein the susceptor is vertically moved into the first processing space, the substrate on the susceptor is controlled at a first temperature, and a modifying gas is supplied to modify a surface layer of the etching target material; and an etching step, wherein the susceptor is vertically moved from the first processing space to the second processing space, the substrate is controlled at a second temperature different from the first temperature, and an etching gas is supplied to remove the modified surface layer, In the etching step, the first processing space and the second processing space are communicated with each other.

2. The atomic layer etching method according to claim 1, characterized in that: In the modification step, the modification gas is supplied by plasma radicalization.

3. The atomic layer etching method according to claim 1, characterized in that: In the etching step, the etching gas is supplied by being plasma radicalized.

4. The atomic layer etching method according to any one of claims 2 or 3, characterized in that: When the modifying gas or the etching gas supplied by being radicalized by the plasma is supplied, the temperature of the substrate is set to 150° C. or less.

5. The atomic layer etching method according to claim 1, characterized in that: The etching target material is a metal oxide film, and the second temperature is set to a temperature higher than the first temperature.

6. The atomic layer etching method according to claim 1, characterized in that: The etching target material is a metal film, and the first temperature is set to a temperature higher than the second temperature.

7. The atomic layer etching method according to claim 1, characterized in that: The modifying step and the etching step are repeated several times.

8. An atomic layer etching device, comprising: A chamber is formed with a first processing space and a second processing space; A gas supply device, used for injecting process gas into the interior of the chamber; A plasma generating part is activated in a plasma environment to convert a process gas supplied from a gas supply part into radicals and supply the radicals to the inside of the chamber; a base, which is arranged facing the gas supply device and can move vertically between the first processing space and the second processing space, and at least one substrate is placed on the upper part; a first temperature control tool configured to surround an upper end portion of an inner wall of the chamber to form the first processing space; a second temperature control tool configured to surround a lower end portion of an inner wall of the chamber to form the second processing space; and a controller that controls the first temperature control tool to control the substrate loaded in the first processing space at the first temperature, and controls the second temperature control tool to control the substrate loaded in the second processing space at the second temperature; The surface layer of the etching target material is modified in any one of the first processing space and the second processing space, and the modified surface layer is etched in the other space. When etching the modified surface layer, the first processing space and the second processing space are connected to each other.

9. The atomic layer etching device according to claim 8, characterized in that: Also includes: An insulating member isolating the first temperature control tool and the second temperature control tool.

10. The atomic layer etching device according to claim 8, characterized in that: The plasma generating part receives the modifying gas or the etching gas supplied from the gas supply part, converts the gas into radicals, and supplies the radicals into the interior of the chamber.

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