Substrate processing method and substrate processing system

Abstract

A substrate processing method and a substrate processing system for forming an air gap structure in a substrate are provided. The substrate processing method includes the steps of: preparing a substrate having a recess having a protrusion; forming a sacrificial layer on the substrate; forming a sealing layer on the sacrificial layer, wherein the etching resistance of the sealing layer is higher than that of the sacrificial layer; and performing plasma etching on the substrate on which the sacrificial layer and the sealing layer are formed to form a sealing part for sealing the upper part of the concave part, thereby forming an air gap structure.

Description

Technical Field

[0001] The present disclosure relates to a substrate processing method and a substrate processing system. Background Art

[0002] Patent Document 1 discloses a method in which an interlayer sacrificial film is gasified and removed through a groove and a gas-permeable film, and a sealing layer is formed to seal the vicinity of the groove opening after the interlayer sacrificial film is removed, thereby forming an air gap.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2010-62242 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] In one aspect, the present disclosure provides a substrate processing method and a substrate processing system for forming an air gap structure on a substrate.

[0008] Solutions for solving problems

[0009] In order to solve the above-mentioned problem, according to one embodiment, a substrate processing method is provided, which includes the following steps: preparing a substrate having a recess having a protrusion; forming a sacrificial layer on the substrate; forming a sealing layer having higher etching resistance than the sacrificial layer on the sacrificial layer; and plasma etching the substrate on which the sacrificial layer and the sealing layer are formed to form a sealing portion that seals the upper part of the recess, thereby forming an air gap structure.

[0010] Effects of the Invention

[0011] According to one aspect, the present disclosure can provide a substrate processing method and a substrate processing system for forming an air gap structure on a substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a diagram illustrating an example of the configuration of a substrate processing system.

[0013] Figure 2 This is a flowchart showing an example of a method for forming an air gap structure.

[0014] Figure 3 This is an example of a schematic cross-sectional view of the substrate W after the processing after step S203.

[0015] Figure 4 This is an example of a schematic cross-sectional view of the substrate W after processing after step S204.

[0016] Figure 5 This is an example of the measurement results of the components of the sealing portion. DETAILED DESCRIPTION

[0017] Hereinafter, the embodiment of the present disclosure will be described with reference to the accompanying drawings. In each of the drawings, the same components are denoted by the same reference numerals, and overlapping descriptions may be omitted.

[0018] [Substrate processing system]

[0019] use Figure 1 The substrate processing system 100 according to this embodiment will be described. Figure 1 1 is a diagram illustrating an example of the configuration of the substrate processing system 100 .

[0020] The substrate processing system 100 is used to transport a concave portion 350 having a groove shape on the surface of a substrate (see Figure 3 ) of the substrate W, by forming a sealing portion 325 (see Figure 4 ) to form an air gap structure 360 ​​on a substrate W.

[0021] Furthermore, by forming the recess 350 into the air gap structure 360 ​​, the relative dielectric constant in the recess 350 can be reduced compared to a case where a dielectric (insulator) is buried in the recess 350 .

[0022] Furthermore, by forming a plurality of elements such as transistors on the substrate W and forming an air gap structure 360 ​​between one element and the other adjacent elements, leakage of current between the one element and the other elements can be suppressed.

[0023] The substrate processing system 100 includes a first film forming apparatus 110, a second film forming apparatus 120, and an etching apparatus 130. In addition, the first film forming apparatus 110, the second film forming apparatus 120, and the etching apparatus 130 may also be as follows. Figure 1 As shown, the substrates W are configured as separate devices. Alternatively, the processing can be performed within the same device. Furthermore, the substrates W can be transported between the first film forming device 110, the second film forming device 120, and the etching device 130 in either an atmospheric atmosphere or a vacuum atmosphere.

[0024] The first film forming apparatus 110 is used to form a sacrificial layer 310 (see FIG. Figure 3) film forming apparatus. Regarding the sacrificial layer 310, for example, silicon oxide and a film mainly composed of silicon oxide are formed as the sacrificial layer 310. Specifically, SiO2 or the like is formed as the sacrificial layer 310. In addition, the sacrificial layer 310 is not limited thereto. For example, the sacrificial layer 310 may be formed without using plasma treatment and low-density SiOC, SiOCN or the like may be used as the sacrificial layer 310. In addition, the first film forming apparatus 110 can use a film forming apparatus such as an ALD (Atomic Layer Deposition) apparatus and a CVD (Chemical Vapor Deposition) apparatus. In addition, in order to form the sacrificial layer 310 with good coverage in the recess 350, it is preferable to use an ALD apparatus.

[0025] The second film forming apparatus 120 is used to form a sealing layer 320 (see FIG. Figure 3 ) film forming apparatus. Regarding the sealing layer 320, for example, a film mainly composed of aluminum oxide, aluminum hydroxide (AlO(OH)), and AlO doped with oxides such as Mg, Zn, and Mn is formed as the sealing layer 320. Specifically, AlO, AlMgO, AlZnO, AlMnO, etc. are formed as the sealing layer 320. In addition, the second film forming apparatus 120 can use a film forming apparatus such as an ALD apparatus and a CVD apparatus. In addition, in order to form the sealing layer 320 with good coverage in the recess 350, it is preferable to use an ALD apparatus.

[0026] The etching device 130 is used to etch the sacrificial layer 310 and the sealing layer 320 (see Figure 3 ) is etched. The air gap structure 360 ​​is formed by etching the sacrificial layer 310 and the sealing layer 320 (refer to Figure 4 ). In addition, the etching device 130 can use a parallel plate type plasma etching device. The parallel plate type plasma etching device generates capacitively coupled plasma (CCP: Capacitively Coupled Plasma). In addition, the plasma etching device is a dry etching device that contains CF-based gas (a gas containing carbon (C) and fluorine (F)) as an etching gas. The plasma etching device causes ions to collide in a vertical direction of the substrate W to perform etching in the vertical direction (anisotropic etching). In addition, the CF-based gas can use, for example, C4F8 gas, CF4 gas, etc. In addition, in addition to the CF-based gas, O2 gas can also be added to the etching gas. In addition, Ar gas and N2 gas can also be added to the etching gas.

[0027] In addition, the etching gas, etching conditions, etc. of the etching device 130 may also use the etching gas, etching conditions, etc. for plasma etching of the sacrificial layer 310 .

[0028] Here, during the plasma etching process in etching apparatus 130, sacrificial layer 310 and sealing layer 320 have different etching resistances. Specifically, the etching rate of sacrificial layer 310 is higher than the etching rate of sealing layer 320. In other words, sealing layer 320 has higher etching resistance than sacrificial layer 310. In other words, sacrificial layer 310 is an easily etched layer, while sealing layer 320 is a difficult-to-etch layer. For example, while the dry etching rate in SiO2, which serves as sacrificial layer 310, is 50 nm / min, the dry etching rate in AlMgO, which serves as sealing layer 320, is 2 nm / min.

[0029] Next, use Figures 2 to 4 To illustrate the air gap structure 360 ​​(refer to Figure 4 ) formation method. Figure 2 This is a flowchart showing an example of a method for forming the air gap structure 360 ​​. Figure 3 This is an example of a schematic cross-sectional view of the substrate W after the processing after step S203. Figure 4 This is an example of a schematic cross-sectional view of the substrate W after processing after step S204.

[0030] In step S201, a substrate W having a recess 350 is prepared. Here, recess 350, such as a groove, is formed on the surface of layer 300 of substrate W. Furthermore, recess 350 has a protruding shape, with the width near the opening narrower than the width of the center portion in the height direction. Specifically, a protrusion 351 is formed on the sidewall of recess 350, tilting inwardly beyond vertical direction.

[0031] In step S202 , a sacrificial layer 310 is formed on the substrate W. Here, the sacrificial layer 310 is formed on the substrate W by the first film forming apparatus 110 . In the following description, it is assumed that SiO 2 is formed as the sacrificial layer 310 .

[0032] In step S203 , the sealing layer 320 is formed on the substrate W. Here, the sealing layer 320 is formed on the substrate W by the second film forming apparatus 120 . In the following description, it is assumed that AlMgO is formed as the sacrificial layer 310 .

[0033] like Figure 3 As shown, a sacrificial layer 310 is formed on the sidewalls and top of the recess 350 (the upper surface of the layer 300) of the substrate W. Here, the sacrificial layer 310 is well formed on the sidewalls and top of the recess 350 with a substantially uniform film thickness. As a result, a protrusion is formed on the sidewalls of the sacrificial layer 310 that is inclined toward the inside of the recess 350, exceeding the vertical.

[0034] Furthermore, a sealing layer 320 is formed on the substrate W on the sacrificial layer 310. Here, the sacrificial layer 310 is formed with good coverage and a substantially uniform film thickness along the sacrificial layer 310. Consequently, a protrusion 321 is formed on the sidewall of the recess 350 in the sacrificial layer 310, tilting inwardly from the vertical toward the recess 350.

[0035] In step S204 , the sacrificial layer 310 and the sealing layer 320 formed on the substrate W are etched to form the sealing portion 325 above the recess 350 . Here, the sacrificial layer 310 and the sealing layer 320 formed on the substrate W are etched by the etching device 130 .

[0036] Here, the plasma etching conditions can be conditions for etching SiO 2 as the sacrificial layer 310. For example, C 4 F 8 gas to which O 2 gas is added can be used as the etching gas.

[0037] Here, changes in the shape of the substrate W when plasma etching is performed will be described.

[0038] First, plasma etching is performed by causing ions to strike the substrate W in a direction perpendicular to the substrate W, thereby etching in the vertical direction. This forms cracks between the top portion 322 and the protrusion 321 of the sealing layer 320. For example, cracks are formed in a portion of the surface of the sealing layer 320 where the ions are incident during plasma etching and where the curvature of the sealing layer 320 is small and stress is applied to the sealing layer 320.

[0039] Next, plasma etching is continued to etch the sacrificial layer 310 from the cracked portion of the sealing layer 320. Here, the sacrificial layer 310 in contact with the protrusion 321 of the sealing layer 320 formed on the upper sidewall of the recess 350 is etched.

[0040] As a result, the protrusion 321 of the sealing layer 320 is in a state of being supported on one side, with the upper side not supported by the sacrificial layer 310 and the lower side supported by the sacrificial layer 310. Here, the protrusion 321 of the sealing layer 320 supported on one side has one surface facing the recess 350 side and the other surface on the opposite side (the surface in contact with the sacrificial layer 310 before etching). The other surface of the protrusion 321 of the sealing layer 320 supported on one side faces the incident direction of ions incident during plasma etching.

[0041] Furthermore, by further continuing the plasma etching, ions are implanted and / or collided with the other surface (the surface in contact with the sacrificial layer 310 before etching) of the protrusion 321 of the sealing layer 320 supported on one side. As a result, the protrusion 321 of the sealing layer 320 supported on one side bends (deforms) toward the inside of the recess 350.

[0042] Furthermore, the upper ends of the protrusions 321 of the sealing layer 320 bent from the two walls meet at the upper portion (near the opening) of the recess 350. Figure 4 As shown, a sealing portion 325 is formed to seal the upper portion of the recess 350 .

[0043] Furthermore, reaction byproducts generated when etching the sacrificial layer 310 are deposited on the curved protrusion 321. The sealing portion 325 includes the deposited reaction byproducts in addition to the protrusion 321 of the sealing layer 320 that is bent from both walls.

[0044] Thus, the protrusions 321 of the sealing layer 320 bent from the two walls are bonded by the deposited reaction by-products.

[0045] Here, use Figure 5 An example of the composition of the sealing portion 325 will be described. Figure 5 Show Figure 4 An example of the measurement results of the composition of the sealing portion 325 at the position indicated by the dotted line 400. Here, the element composition of the sealing portion 325 was measured by energy dispersive X-ray spectroscopy (EDX), and the composition ratios of O, F, Mg, Al, and Si were detected.

[0046] The sealing portion 325 contains Al, Mg, and O derived from the sealing layer 320 (AlMgO).

[0047] In addition, the sealing portion 325 contains Si, F, and O which are reaction by-products when the sacrificial layer 310 (SiO 2 ) is plasma-etched using an etching gas (C 4 F 8 gas to which O 2 gas is added).

[0048] In this manner, the sealing portion 325 is formed by the protrusion 321 bent from both walls and reaction byproducts when the sacrificial layer 310 is etched.

[0049] As above, as Figure 4 As shown, a sealing portion 325 is formed on the upper portion of the recess 350, and the opening of the recess 350 is sealed by the sealing portion 325. In other words, the sealing portion 325 is formed as a cover to block the opening of the recess 350. Thus, the recess 350 and the sealing portion 325 form an air gap structure 360.

[0050] Furthermore, the etching rate of the sacrificial layer 310 is preferably 10 times or more higher than the etching rate of the sealing layer 320. This allows the protrusion 321 of the sealing layer 320 to be formed while suppressing consumption of the sealing layer 320.

[0051] In addition, it is preferred that the film thickness of the sealing layer 320 is in the range of 2 nm or more and 10 nm or less during film formation (at the end of S203). By setting the film thickness of the sealing layer 320 to 2 nm or more, the protrusion 321 of the sealing layer 320 supported on one side can be stably formed. In addition, by setting the film thickness of the sealing layer 320 to 10 nm or less, cracks can be formed in the sealing layer 320 and the sacrificial layer 310 can be etched from the cracks. Thus, the protrusion 321 of the sealing layer 320 supported on one side can be stably formed. In addition, by setting the film thickness of the sealing layer 320 to 10 nm or less, the protrusion 321 of the sealing layer 320 can be appropriately bent (deformed) toward the inside of the recess 350 by ion implantation and / or impact.

[0052] The sealing layer 320 is preferably thinner than the sacrificial layer 310. By increasing the thickness of the sacrificial layer 310, the sacrificial layer 310 can be properly etched when etching the sacrificial layer 310 from the cracks in the sealing layer 320.

[0053] Alternatively, the sealing layer 320 may be composed of two layers: a layer formed of AlMgO, AlO, etc. and then bent to form the sealing portion 325, and a passivation layer formed on the layer. The passivation layer can improve the etching resistance of the sealing layer 320.

[0054] Furthermore, although the sealing portion 325 is formed by the upper end portions of the protrusions 321 bent from both walls contacting each other at the opening of the recess 350 , the present invention is not limited thereto.

[0055] The sealing portion 325 may also have the following structure: the upper ends of the protrusions 321 bent from the two walls do not contact each other, and there is a gap between the upper ends of the protrusions 321 bent from the two walls. That is, the sealing portion 325 may also have a gap. Even with the sealing portion 325 having such a gap, the opening of the recess 350 can be narrowed by forming the protrusions 321 bent from the two walls. In addition, the sealing portion 325 may be formed as follows: after narrowing the opening of the recess 350 by plasma etching, a film is formed on the sealing portion 325 having the gap by a film forming method with a low coverage rate, thereby closing the gap of the sealing portion 325.

[0056] While the method for forming the air gap structure 360 ​​according to one embodiment is described above using the substrate processing system 100 , the present disclosure is not limited to the above embodiment and various modifications and improvements are possible within the scope of the gist of the present disclosure as described in the claims.

[0057] In addition, this application claims priority based on Japanese Patent Application No. 2023-20295 for which it applied on February 13, 2023, and all the contents of this Japanese Patent Application are incorporated into this application by reference.

[0058] Description of Reference Numerals

[0059] W: substrate; 100: substrate processing system; 110: first film forming device; 120: second film forming device; 130: etching device; 300: layer; 310: sacrificial layer; 320: sealing layer; 321: protrusion; 322: top; 325: sealing part; 350: recess; 351: protrusion; 360: air gap structure.

Claims

1. A substrate processing method comprising the following steps: preparing a substrate having a recessed portion, wherein the recessed portion has a protrusion; forming a sacrificial layer on the substrate; forming a sealing layer on the sacrificial layer, the sealing layer having higher etching resistance than that of the sacrificial layer; as well as The substrate on which the sacrificial layer and the sealing layer are formed is subjected to plasma etching to form a sealing portion that seals an upper portion of the recess, thereby forming an air gap structure.

2. The substrate processing method according to claim 1, wherein: The process of etching the substrate is as follows: forming cracks in the sealing layer; etching the sacrificial layer from the crack in the sealing layer to set the sealing layer formed on the sidewall of the recess to a single-sided state; as well as The air gap structure is formed by bending the sealing layer supported on one side toward the inside of the recess to form the sealing portion in which the upper portion of the recess is sealed by the sealing layer.

3. The substrate processing method according to claim 2, wherein: The crack is formed between the top of the sealing layer and the protruding portion of the sealing layer.

4. The substrate processing method according to any one of claims 1 to 3, wherein: The step of etching the substrate is dry etching using a CF-based gas as etching gas.

5. The substrate processing method according to claim 4, wherein: The process of etching the substrate further includes using O2 gas as the etching gas.

6. The substrate processing method according to any one of claims 1 to 3, wherein: The sacrificial layer is silicon oxide or a film containing silicon oxide as a main component.

7. The substrate processing method according to any one of claims 1 to 3, wherein: The sealing layer is any one of films mainly composed of aluminum oxide, aluminum hydroxide, and AlO doped with oxides of Mg, Zn, and Mn.

8. The substrate processing method according to any one of claims 1 to 3, wherein: In the step of forming the sealing layer, The thickness of the sealing layer during film formation is within a range of 2 nm to 10 nm.

9. The substrate processing method according to any one of claims 1 to 3, wherein: In the process of etching the substrate, The etching rate of the sacrificial layer is more than 10 times that of the sealing layer.

10. A substrate processing system comprising: forming an air gap structure on a substrate having a recessed portion, wherein the recessed portion has a protrusion; the substrate processing system comprising: a first film forming device for forming a sacrificial layer on the substrate; a second film forming device for forming a sealing layer having higher etching resistance than that of the sacrificial layer on the sacrificial layer; as well as An etching device performs plasma etching on the substrate on which the sacrificial layer and the sealing layer are formed to form a sealing portion that seals an upper portion of the recess, thereby forming an air gap structure.

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