Atomic layer etching method

Abstract

The present invention relates to an atomic layer etching method for etching a substrate surface using an atomic layer etching device. The present invention discloses an atomic layer etching method, comprising: a substrate preparation step (S10), preparing a substrate (100) on a substrate support frame; a modification step (S20), after the substrate preparation step (S10), supplying a modified gas containing a halogen gas other than HF to the substrate (100) through free radicalization by a remote plasma generating device combined with a process chamber, thereby modifying a surface layer (110) of the substrate (100); a first purge step (S30), for purging the surface layer; a surface layer removal step (S40), supplying a metal-containing precursor to the surface layer (110) to remove the surface layer (110) modified in the modification step (S20); and a second purge step (S50), purging the surface of the substrate (100).

Description

Technical Field

[0001] The invention relates to an atomic layer etching method for etching a substrate surface by utilizing an atomic layer etching device. Background Art

[0002] Semiconductor components such as DRAM, NAND flash memory, CPU, mobile CPU, and display panels such as LCD panels, OLED panels, and OLED are manufactured through one or more semiconductor processes such as deposition and etching.

[0003] Figure 1 As a schematic diagram showing a conventional atomic layer etching method, the conventional atomic layer etching method is performed through the following steps: a modification step of modifying a surface layer 110 on a substrate 100 surface using hydrogen fluoride (HF); and a removal step of reacting with the modified surface layer 110 to remove the surface layer 110 .

[0004] Here, conventional atomic layer etching methods generally use hydrogen fluoride, which easily modifies the surface layer due to its strong reactivity.

[0005] On the other hand, the conventional atomic layer etching method is performed while heating the substrate 100 at high temperature during the modification step and the removal step. However, when the process is performed in a high temperature environment, thermal shock is applied to the semiconductor structure formed on the substrate 100, which may cause defects in substrate manufacturing.

[0006] However, hydrogen fluoride (HF) used in conventional atomic layer etching methods has the advantage of being highly reactive, but has the problem of being unsuitable for isotropic process conditions because it reacts more anisotropically in the portion exposed upward than uniformly (isotropically) in the entire surface exposed to hydrogen fluoride.

[0007] On the other hand, when other halogenated substances are used as substitutes for hydrogen fluoride, the reactivity is not as high as that of hydrogen fluoride, so high-temperature heating of the substrate is required to improve the reactivity. However, when the substrate is heated, thermal shock is applied to the element structure formed on the substrate, causing damage to the element structure or reduction in performance.

[0008] (Patent Document 1) KR101080604 B1 Summary of the invention

[0009] (Technical issues to be resolved)

[0010] The present invention is proposed to achieve the above-mentioned purpose, and its purpose is to provide an atomic layer etching method that uses a modified gas obtained by radicalizing a halogen gas other than hydrogen fluoride to perform substrate processing and thereby achieve isotropic etching.

[0011] (Technical solution to the problem)

[0012] The present invention is proposed to achieve the purpose of the present invention as described above. The present invention discloses an atomic layer etching method, as an atomic layer etching method using an atomic layer etching device, the atomic layer etching device includes a process chamber, a gas injection unit, a substrate support frame and a remote plasma generating device, wherein the process chamber forms a sealed processing space, the gas injection unit is arranged on the upper side of the process chamber to inject gas into the processing space, and the substrate support frame is arranged on the lower side of the process chamber to install a substrate, comprising: a substrate preparation step S10, preparing a substrate on the substrate support frame 100; a modification step S20, after the substrate preparation step S10, supplying a modified gas containing a halogen gas other than HF to the substrate 100 through a remote plasma generator combined with the process chamber for radicalization, thereby modifying the surface layer 110 of the substrate 100; a first purge step S30 for purge the surface layer; a surface layer removal step S40, supplying a precursor containing a metal to the surface layer 110 to remove the surface layer 110 modified in the modification step S20; a second purge step S50, purge the surface of the substrate 100.

[0013] The remote plasma generator can convert the modified gas into radicals by one of a CCP method, an ICP method and an electromagnetic wave method.

[0014] The modifying step S20 to the surface layer removing step S40 may be repeated several times as a cycle.

[0015] Preferably, the process pressure of the modification step S20 is the same as or lower than the process pressure of the surface layer removal step S40.

[0016] The distance H between the gas injection part and the substrate is preferably such that the distance H in the modification step S20 and the distance H in the surface layer removal step S40 are the same as each other, or the distance H in the surface layer removal step S40 is longer.

[0017] Preferably, the atomic layer etching method of the present invention is performed at a temperature below 400°C.

[0018] The atomic layer etching method of the present invention may further include a post-processing step S60 , wherein the post-processing step S60 supplies a post-processing gas to post-process the surface of the substrate 100 , thereby removing the halogen compounds remaining on the surface of the substrate 100 after the surface layer removal step S40 .

[0019] The post-processing step S60 may be performed using a gas containing hydrogen or oxygen.

[0020] The post-processing step S60 may be performed by plasma or heating.

[0021] (Effects of the Invention)

[0022] The atomic layer etching method of the present invention utilizes a modified gas of a halogen gas other than hydrogen fluoride to modify the surface layer and remove the modified surface layer, thereby having the advantages of being able to achieve isotropic etching under relatively low temperature conditions while being able to perform substrate processing in an environmentally friendly and stable manner.

[0023] Furthermore, the atomic layer etching method of the present invention utilizes a modified gas obtained by free radicalization of a halogen gas other than hydrogen fluoride to modify the surface layer, and removes the modified surface layer. The process can be performed under relatively low temperature conditions, thereby minimizing the thermal shock to the substrate, thereby minimizing the damage to the semiconductor element or the performance degradation caused by the thermal shock. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram showing a conventional atomic layer etching method.

[0025] Figure 2 is a schematic diagram showing the atomic layer etching method of the present invention.

[0026] Figure 3 1 is a flowchart showing an example of the atomic layer etching method of the present invention.

[0027] (Explanation of Reference Numerals)

[0028] 100: substrate 110: surface layer DETAILED DESCRIPTION

[0029] Hereinafter, the atomic layer etching method of the present invention will be described with reference to the drawings.

[0030] like Figure 2 and Figure 3As shown, the atomic layer etching method of the present invention is an atomic layer etching method using an atomic layer etching device, wherein the atomic layer etching device includes a process chamber, a gas injection part, a substrate support frame and a remote plasma generator, wherein the process chamber forms a sealed processing space, the gas injection part is arranged on the upper side of the process chamber to inject gas into the processing space, and the substrate support frame is arranged on the lower side of the process chamber to install the substrate, comprising: a substrate preparation step S10, preparing a substrate 100 on the substrate support frame; a modification step S20, after the substrate preparation step S10, supplying a modified gas containing a halogen gas other than HF to the substrate 100 through radicalization of the remote plasma generator combined with the process chamber, thereby modifying the surface layer 110 of the substrate 100; a first purge step S30, for purging the surface layer; a surface layer removal step S40, supplying a metal precursor to the surface layer 110 to remove the surface layer 110 modified in the modification step S20; a second purge step S50, purging the surface of the substrate 100.

[0031] First, for the substrate 100 for performing the atomic layer etching method of the present invention, as long as it is a component that includes an etching process in the manufacturing process, it can be any substrate. As an example, it can be a substrate for manufacturing semiconductor elements such as DRAM, NAND flash memory, CPU, mobile CPU, etc., display panels such as LCD panels, OLED panels, etc., and can be various substrates.

[0032] Then, in the substrate 100, the physical properties of the etching target layer are Al2O3, HfO2, and ZrO2, and Al2O3 is the most preferred. Figure 2 Target materials are used in the figure to emphasize the physical properties of the etching object of the substrate 100.

[0033] In addition, the atomic layer etching method of the present invention is performed by an atomic layer etching device.

[0034] The atomic layer etching apparatus is an apparatus that replaces deposition with etching in a manner similar to the atomic layer deposition method, and can realize various structures.

[0035] As an example, similar to Patent Document 1, the atomic layer etching device may include: a process chamber, forming a sealed processing space; a gas injection part, arranged on the upper side of the process chamber to inject gas into the processing space; a substrate support frame, arranged on the lower side of the process chamber to install the substrate; and a remote plasma generating device.

[0036] The process chamber is a structure that forms a sealed processing space for performing an etching process, and may realize various structures, such as a chamber body with an upper side opened and a rod detachably coupled to the chamber body.

[0037] The gas injection part is a structure provided at an upper side of the process chamber to inject gas into the processing space, such as a substrate support frame, and may realize various structures.

[0038] The substrate support frame is a structure arranged at the lower side of the process chamber to mount the substrate, and various structures can be realized. Here, the substrate support frame can be provided with a lifting assembly, a heater, an electrostatic chuck, etc., wherein the lifting assembly is used to move the substrate up and down on the substrate support frame, the heater is used to heat the substrate mounted on the substrate support frame, and the electrostatic chuck absorbs and fixes the substrate through electrostatic force.

[0039] In addition, the substrate support frame may need to be changed in distance from the gas injection portion when exchanging substrates or performing processes, and in this case, the substrate support frame may be provided to be movable up and down.

[0040] The remote plasma generating device is combined with a gas injection unit to transfer gas, and further combined with a process chamber to supply a modified gas to be described later, and then the modified gas is converted into radicals and then injected through the gas injection unit.

[0041] Then, the remote plasma generating device can use CCP (Capacitor coupled plasma), ICP (Inductively Coupled Plasma), electromagnetic wave (Micro Waver), etc. as the plasma generating method.

[0042] The substrate preparation step S10 is a step of preparing the substrate 100 on the substrate support frame, and can be performed by various methods according to the substrate conveying method and the substrate exchanging method.

[0043] For example, the substrate preparation step S10 is to mount the substrate 100 to be processed on a substrate support frame after the substrate 100 that has been processed is transported out by an actuator of a transport robot (not shown).

[0044] At this time, a lifting pin assembly may be provided on the substrate support frame to receive the substrate 100 from the actuator of the transfer robot, and the substrate support frame can be lifted up and down together with the lifting pin assembly to lift the substrate 100 on the upper surface of the substrate support frame.

[0045] The modifying step S20 is a step of radicalizing a modifying gas including a halogen gas other than HF by a remote plasma generator coupled to a process chamber to modify the surface layer 110 of the substrate 100 after the substrate preparation step S10 , and can be performed by various methods.

[0046] exist Figure 2 In the figure, considering that the surface layer 110 has been modified, the surface layer 110 is represented by modified layer.

[0047] The modified gas may be a gas containing a halogen gas other than HF, and may include a gas containing NF3, F2, CF4, HCl, HBr, SF6, Cl2, or the like other than HF.

[0048] Then, the modification step S20 is as described above, the remote plasma generator for radicalizing the modified gas can use CCP (Capacitor coupled plasma) method, ICP (Inductively Coupled Plasma) method, electromagnetic wave (Micro Waver) method, etc.

[0049] In addition, the substrate 100 is modified by performing the modification step S20 so that the physical property of the surface layer 110 can be removed by performing the subsequent surface layer removal step S40 .

[0050] As an example, when the physical property of the etching target substrate 100 is Al 2 O 3 and the reforming gas is one of NF 3 , F 2 , and CF 4 , the physical property of the surface layer 110 after the reforming step S20 is changed from Al 2 O 3 to AlF.

[0051] On the other hand, the substrate 100 having the physical property of Al 2 O 3 should be heated at a temperature of 500° C. or more to react with the reforming gas, but this may cause thermal problems in the device formed on the substrate 100 .

[0052] Accordingly, if the modifying gas is converted into radicals and then sprayed onto the substrate 100 to modify the surface layer 110 when the modifying gas is sprayed onto the substrate 100 , the surface layer 110 of the substrate 100 can be modified under relatively low temperature conditions.

[0053] The first purging step S30 is a step for purging the surface layer and can be performed by various methods.

[0054] As an example, the first purging step S30 may be performed using an inert gas such as argon (Ar) to remove the modifying gas remaining on the surface of the substrate 100 .

[0055] Here, during the modification step S20 , an inert gas such as argon (Ar) is continuously injected into a process chamber (not shown), and then the first purge step S30 may be continuously performed after the modification gas is injected.

[0056] The surface layer removal step S40 , which is a step of supplying a precursor including a metal to the surface layer 110 to remove the surface layer 110 modified in the modification step S20 , may be performed by various methods.

[0057] The metal-containing precursor is used as a precursor for removing the surface layer 110 modified after the modification step S20 , and changes according to the physical properties of the modified surface layer 110 .

[0058] As an example, when the physical properties of the etching target layer in the substrate 100 are Al2O3, HfO2, or ZrO2, the precursor containing the metal may be a precursor such as TMA, DMAI, or ACAC.

[0059] As a specific example, after performing the modification step S20 , the physical property of the surface layer 110 is changed from Al 2 O 3 to AlF, and in the surface layer removal step S40 , AlF can be removed by a metal organic precursor (Metal organic precursor) such as TMA or DMAI, ACAC, etc.

[0060] exist Figure 2 In the figure, the layer removed by the metal-containing precursor is represented by Etched layer thickness.

[0061] The second purging step S50 is a step of purging the surface of the substrate 100 and can be performed by various methods.

[0062] Here, during the modification step S20 and the surface layer removal step S40 , an inert gas such as argon (Ar) is continuously sprayed into the process chamber (not shown), and then after the modification gas is injected, the second purge step S50 can be continuously performed together with the first purge step S30 .

[0063] On the other hand, the modification step S20 to the surface layer removal step S40 is a cycle, which can be repeatedly performed several times according to the thickness of the surface layer 110 to be removed.

[0064] That is, in order to etch the substrate 100 to the desired thickness, the modifying step S20 to the surface layer removing step S40 may be repeatedly performed several times as a cycle.

[0065] On the other hand, after performing the surface layer removing step S40 , the modified surface layer 110 is not completely removed, but a portion remains on the substrate 100 .

[0066] That is, after performing the surface layer removal step S40 , the modified substance remaining on the substrate 100 needs to be removed.

[0067] Accordingly, the atomic layer etching method of the present invention may further include a post-processing step S60, wherein the post-processing step S60 is to supply a post-processing gas to post-process the surface of the substrate 100 to remove the halogen compounds remaining on the surface of the substrate 100 after the surface layer removal step S40.

[0068] The post-treatment step S60 is a step of removing the halogen compound remaining on the surface of the substrate 100 after the surface layer removal step S40 , and can be performed by various methods.

[0069] Considering that the physical property to be removed is a halogen compound, the post-treatment gas may use a gas containing hydrogen (H) or oxygen (O).

[0070] More specifically, the post-treatment gas includes H2O, H2O2, NH3, H2, etc. as a gas containing hydrogen (H), and includes H2O, H2O2, O2, O3, etc. as a gas containing oxygen (O).

[0071] On the other hand, in the case of H2O, H2O2, and O3, the residual halogen compounds can be removed by heating the substrate, but in the case of NH3, H2, and O2, the reactivity is low and the residual halogen compounds can be removed by plasma radicalization.

[0072] That is, the post-processing step S60 may be performed by applying plasma to the post-processing gas.

[0073] Here, the post-processing gas may be converted into radicals by using a remote plasma generating device.

[0074] At this time, the remote plasma generating device for radicalizing the post-processing gas may be the remote plasma generating device for radicalizing the modifying gas described above.

[0075] Then, the remote plasma generating device can use a CCP (Capacitor coupled plasma) method, an ICP (Inductively Coupled Plasma) method, an electromagnetic wave (Micro Waver) method, etc.

[0076] On the other hand, the atomic layer etching method of the present invention, when including the post-processing step S60, can repeatedly perform the modification step S20 to the post-processing step S60 as one cycle for several times.

[0077] As another example, the atomic layer etching method of the present invention is to repeatedly perform the modification step S20 to the surface layer removal step S40 as a cycle for several times, and then finally perform the post-processing step S60.

[0078] On the other hand, as described above, the atomic layer etching method of the present invention including the modification step S20 to the surface layer removal step S40 or the modification step S20 to the post-processing step S60 can be performed under various process conditions, and can be performed continuously in a process chamber or in individual steps or only the surface layer removal step S40 can be performed in an independent process chamber.

[0079] As an example, the atomic layer etching method of the present invention can be performed in a process chamber while changing process conditions according to each step, wherein the process chamber has a susceptor on which the substrate 100 is mounted and a substrate support frame disposed on top of the susceptor.

[0080] Here, the process pressure of the modifying step S20 is the same as or lower than the process pressure of the surface layer removing step S40 and can be performed under this condition.

[0081] If the modification step S20 is performed under the condition that the process pressure is the same as or lower than the process pressure of the surface layer removal step S40, the mean free path of the modification gas and the lifetime of the free radicals are increased, and the modification gas can also be supplied in the pattern with a large aspect ratio (AR).

[0082] In the case of the modification step S20 , if the process pressure is high, a modified surface layer 110 with a relatively large thickness may be formed, so it is preferably performed under a relatively low process pressure.

[0083] In this regard, the surface layer removal step S40 is to effectively remove the surface layer 110 in a short time, so it is preferably performed under a relatively high process pressure.

[0084] As a similar process condition, a base on which the substrate 100 is mounted is arranged to be movable up and down. At this time, the distance H between the gas injection portion and the substrate is the same as the distance H in the modification step S20 and the distance H in the surface layer removal step S40, or the distance H in the surface layer removal step S40 is longer, and it can be performed under this condition.

[0085] In the case of the modification step S20 , if the process distance H between the gas injection part and the substrate is short, a modified surface layer 110 with a relatively large thickness can be formed, so it is preferably performed under the condition that the distance H is relatively long.

[0086] In this regard, the surface layer removal step S40 is to effectively remove the surface layer 110 in a short time, so it is preferably performed at a relatively short process distance H.

[0087] Furthermore, the distance between the substrate support frame and the substrate is adjusted, so if the distance becomes longer in the modification step S20, the surface density of the substrate 100 is relatively reduced, and the mean free path (Mean freepath) of the modified gas is ultimately increased, thereby allowing the modified gas to be supplied within a pattern with a large aspect ratio (AR).

[0088] On the other hand, the atomic layer etching method of the present invention is characterized in that the thermal impact on the substrate 100 is minimized in performing surface etching, and therefore is preferably performed at a temperature of 400° C. or less.

[0089] The above only describes a part of the preferred embodiments that can be implemented by the present invention. It is well known that the scope of the present invention is not limited to the above embodiments. The technical ideas of the present invention described above and their fundamental technical ideas are all included in the scope of the present invention.

Claims

1. An atomic layer etching method, as an atomic layer etching method using an atomic layer etching device, the atomic layer etching device comprises a process chamber, a gas injection unit, a substrate support frame and a remote plasma generating device, wherein the process chamber forms a sealed processing space, the gas injection unit is arranged on the upper side of the process chamber to inject gas into the processing space, and the substrate support frame is arranged on the lower side of the process chamber to install the substrate, characterized in that: include: A substrate preparation step (S10), preparing a substrate (100) on the substrate support frame; a modification step (S20), after the substrate preparation step (S10), supplying a modification gas containing a halogen gas other than HF to the substrate (100) through a remote plasma generator coupled to the process chamber to radicalize the gas, thereby modifying the surface layer (110) of the substrate (100); A first purging step (S30) for purging the surface layer; a surface layer removing step (S40) of supplying a precursor containing a metal to the surface layer (110) to remove the surface layer (110) modified in the modifying step (S20); The second purging step (S50) is to purge the surface of the substrate (100). The substrate support frame is configured to be movable up and down. The process distance (H) between the gas injection part and the substrate is, The process distance (H) in the modification step (S20) is longer than the process distance (H) in the surface layer removal step (S40), The modifying step (S20) to the surface layer removing step (S40) are repeatedly performed several times as a cycle, and the modifying step (S20) to the surface layer removing step (S40) are continuously performed in one process chamber.

2. The atomic layer etching method according to claim 1, characterized in that: The remote plasma generator converts the modified gas into radicals by one of a CCP method, an ICP method and an electromagnetic wave method.

3. The atomic layer etching method according to claim 1 or 2, characterized in that: The process pressure of the modifying step (S20) is the same as or lower than the process pressure of the surface layer removing step (S40).

4. The atomic layer etching method according to claim 1 or 2, characterized in that: The atomic layer etching method is performed at a temperature below 400°C.

5. The atomic layer etching method according to claim 1 or 2, characterized in that: Also includes: A post-treatment step (S60) is to supply a post-treatment gas to post-treat the surface of the substrate (100), thereby removing the halogen compound remaining on the surface of the substrate (100) after the surface layer removal step (S40).

6. The atomic layer etching method according to claim 5, characterized in that: The post-treatment step (S60) is performed using a gas containing hydrogen or oxygen.

7. The atomic layer etching method according to claim 6, characterized in that: The post-treatment step (S60) is performed by plasma or heating.

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