Film forming method and processing apparatus

Abstract

To provide a technology that can form boron-containing silicon films with good adhesion.SOLUTION: A film deposition method according to an aspect of the present disclosure has the steps of forming a boron nitride film on a substrate and forming a boron-containing silicon film on the boron nitride film.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a film forming method and a processing apparatus. [Background technology]

[0002] A technique is known in which a seed layer made of a boron-based thin film is formed on the wafer surface, and then a carbon film is formed thereon (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-210640 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique for forming a boron-containing silicon film with good adhesion. [Means for solving the problem]

[0005] A film forming method according to one aspect of the present disclosure includes: A first process gas containing a boron-containing gas, a nitrogen-containing gas, and a hydrogen gas is supplied to the substrate; forming a boron nitride film on a substrate; supplying a second process gas to the substrate, the second process gas including the boron-containing gas, the silicon-containing gas, and a hydrogen gas; and forming a boron-containing silicon film on the boron nitride film. Effect of the Invention

[0006] According to the present disclosure, a boron-containing silicon film with good adhesion can be formed. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic diagram illustrating an example of a processing apparatus according to an embodiment; [Diagram 2] 1 is a flowchart showing an example of a film forming method according to an embodiment. [Diagram 3] 1 is a cross-sectional view showing a process of an example of a film forming method according to an embodiment; [Figure 4] FIG. 1 is a diagram for explaining the bonding state on the substrate surface. [Diagram 5] A diagram showing a part of the manufacturing process of a semiconductor device using a B-Si film. [Figure 6] A diagram for explaining the method for evaluating the adhesion of a B-Si film. [Figure 7] Figure showing the results of evaluating the adhesion of B-Si film [Figure 8] Figure showing the results of evaluating the adhesion of B-Si film [Figure 9] Figure showing the results of evaluating the adhesion of B-Si film DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, non-limiting exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. In all of the accompanying drawings, the same or corresponding members or parts are designated by the same or corresponding reference numerals, and duplicated descriptions will be omitted.

[0009] [Processing Device] An example of a processing apparatus according to an embodiment will be described with reference to FIG.

[0010] The processing apparatus 100 is configured as a vertical batch-type film forming apparatus. The processing apparatus 100 includes a cylindrical outer tube 101 with a ceiling, and a cylindrical inner tube 102 provided inside the outer tube 101. The outer tube 101 and the inner tube 102 are made of, for example, quartz, and the inner region of the inner tube 102 forms a processing chamber S in which a plurality of substrates W to be processed are processed at once. The substrates W may be, for example, semiconductor wafers.

[0011] The outer pipe 101 and the inner pipe 102 are separated from each other in the horizontal direction with the annular space 104 between them, and their lower ends are joined to a base material 105. The upper end of the inner pipe 102 is separated from the ceiling of the outer pipe 101, and the upper part of the processing chamber S is connected to the annular space 104. The annular space 104 connected to the upper part of the processing chamber S serves as an exhaust path. The gas supplied to the processing chamber S and diffused flows from the lower part of the processing chamber S to the upper part of the processing chamber S and is sucked into the annular space 104. An exhaust pipe 106 is connected to, for example, the lower end of the annular space 104, and the exhaust pipe 106 is connected to an exhaust device 107. The exhaust device 107 is configured to include a vacuum pump or the like, and exhausts the processing chamber S and adjusts the internal pressure of the processing chamber S to a pressure appropriate for processing.

[0012] A heating device 108 is provided outside the outer tube 101 so as to surround the periphery of the processing chamber S. The heating device 108 adjusts the temperature inside the processing chamber S to a temperature appropriate for processing, and heats multiple substrates W collectively.

[0013] The lower part of the processing chamber S is in communication with an opening 109 provided in the base material 105. A manifold 110 formed in a cylindrical shape from, for example, stainless steel is connected to the opening 109 via a seal member 111 such as an O-ring. The lower end of the manifold 110 is opened, and a boat 112 is inserted into the processing chamber S through this opening. The boat 112 is made of, for example, quartz, and has a plurality of supports 113. The supports 113 are formed with grooves (not shown), and the grooves support a plurality of substrates to be processed at once. This allows the boat 112 to mount a plurality of substrates W (for example, 50 to 150 substrates) in multiple stages. By inserting the boat 112 on which the plurality of substrates W are mounted into the processing chamber S, the processing chamber S can accommodate a plurality of substrates W.

[0014] The boat 112 is placed on a table 115 via a thermal insulation tube 114 made of quartz. The table 115 is supported on a rotating shaft 117 penetrating a lid 116 made of, for example, stainless steel. The lid 116 opens and closes an opening at the lower end of the manifold 110. A magnetic fluid seal 118, for example, is provided at the penetrating portion of the lid 116, and rotatably supports the rotating shaft 117 while sealing it airtight. A seal member 119 made of, for example, an O-ring is interposed between the periphery of the lid 116 and the lower end of the manifold 110, and keeps the inside of the processing chamber S airtight. The rotating shaft 117 is attached to the tip of an arm 120 supported by a lifting mechanism (not shown) such as a boat elevator. As a result, the boat 112 and the lid 116 are vertically raised and lowered together to be inserted into and removed from the processing chamber S.

[0015] The processing apparatus 100 has a processing gas supply unit 130 that supplies a processing gas inside the processing chamber S. In this embodiment, the processing gas supply unit 130 includes a boron-containing gas supply source 131a, a nitrogen-containing gas supply source 131b, a silicon-containing gas supply source 131c, and an inert gas supply source 131d.

[0016] The boron-containing gas supply source 131a is connected to a gas supply port 134a via a flow rate controller (MFC) 132a and an on-off valve 133a. The nitrogen-containing gas supply source 131b is connected to a gas supply port 134b via a flow rate controller (MFC) 132b and an on-off valve 133b. The silicon-containing gas supply source 131c is connected to a gas supply port 134c via a flow rate controller (MFC) 132c and an on-off valve 133c. The inert gas supply source 131d is connected to a gas supply port 134d via a flow rate controller (MFC) 132d and an on-off valve 133d. The gas supply ports 134a to 134d are each provided to penetrate a side wall of the manifold 110 in the horizontal direction, and diffuse the supplied gas toward the inside of the processing chamber S located above the manifold 110.

[0017] The boron-containing gas supplied from the boron-containing gas supply source 131a is used to form a boron-containing silicon film (B-Si film) by, for example, thermal CVD. The boron-containing gas supplied from the boron-containing gas supply source 131a is also used to form a boron nitride film (BN film) on the underlayer by thermal CVD in order to improve the adhesion between the underlayer and the B-Si film. As the boron-containing gas, for example, a borane-based gas such as diborane (B2H6), boron trichloride (BCl3), or a gas obtained by diluting these gases with hydrogen (H2), nitrogen (N2), or the like can be used.

[0018] The nitrogen-containing gas supplied from the nitrogen-containing gas supply source 131b is used to form a BN film together with a boron-containing gas, for example. As the nitrogen-containing gas, one or more gases selected from the group consisting of ammonia (NH), diazene (N2H2), hydrazine (N2H4), and organic hydrazine compounds such as monomethylhydrazine (CH3(NH)NH2) can be used.

[0019] The silicon-containing gas supplied from the silicon-containing gas supply source 131c is used to form a B-Si film together with, for example, a boron-containing gas. As the silicon-containing gas, for example, one or more gases selected from the group consisting of monosilane (SiH4), disilane (Si2H6), hexachlorodisilane (HCD), dichlorosilane (DCS), hexaethylaminodisilane, hexamethyldisilazane (HMDS), tetrachlorosilane (TCS), disilylamine (DSA), trisilylamine (TSA), and bis(tert-butylaminosilane) (BTBAS) can be used.

[0020] The inert gas supplied from the inert gas supply source 131d is used, for example, to purge the inside of the processing chamber S. As the inert gas, for example, a rare gas such as N2 gas or Ar gas can be used.

[0021] The processing device 100 has a control unit 150. The control unit 150 includes a process controller 151 formed of, for example, a microprocessor (computer), and the process controller 151 controls each component of the processing device 100. A user interface 152 and a storage unit 153 are connected to the process controller 151.

[0022] The user interface 152 includes an input unit and a display unit. The input unit includes a touch panel display, a keyboard, and the like, which allow an operator to input commands to manage the processing device 100. The display unit includes a display that visualizes and displays the operating status of the processing device 100.

[0023] The storage unit 153 stores so-called process recipes, which include control programs for implementing various processes executed by the processing apparatus 100 under the control of the process controller 151, and programs for causing each component of the processing apparatus 100 to execute processes according to processing conditions. The process recipes are stored in a storage medium in the storage unit 153. The storage medium may be a hard disk or a semiconductor memory, or may be a portable medium such as a CD-ROM, a DVD, or a flash memory. The process recipes may also be appropriately transmitted from another apparatus via, for example, a dedicated line.

[0024] The process recipe is read from the storage unit 153 as required, for example, in response to an instruction from an operator via a user interface 152, and the process controller 151 causes the processing device 100 to execute processing in accordance with the read process recipe.

[0025] [Film formation method] 2 to 4, the film forming method of the embodiment will be described by taking as an example a case where the film forming method is performed by the above-mentioned processing apparatus 100. However, the film forming method of the embodiment can also be performed by an apparatus other than the above-mentioned processing apparatus 100.

[0026] As shown in FIG. 2, the film forming method of the embodiment includes a step S1 of preparing a substrate, a step S2 of forming a BN film on the substrate, and a step S3 of forming a B—Si film on the BN film.

[0027] In the step S1 of preparing a substrate, as shown in FIG. 3(a), a substrate W having a base 12 formed on a base 11 is prepared. In this embodiment, a plurality of substrates W (e.g., 50 to 150 substrates) having a base 12 formed on a base 11 are loaded on a boat 112, and the boat 112 is inserted from below into the processing chamber S of the processing device 100 to carry the plurality of substrates W into the processing chamber S. Next, the lower end opening of the manifold 110 is closed with the lid 116 to make the processing chamber S a sealed space. In this state, the processing chamber S is evacuated to maintain a predetermined reduced pressure atmosphere, and the power supplied to the heating device 108 is controlled to raise the substrate temperature and maintain it at the process temperature, and the boat 112 is rotated. The base 12 may be, for example, a SiN film or a SiCN film.

[0028] In the step S2 of forming the BN film, as shown in FIG. 3(b), the BN film 13 is formed on the underlayer 12 by, for example, thermal CVD. In this embodiment, a boron-containing gas is supplied from the boron-containing gas supply source 131a into the processing chamber S, and a nitrogen-containing gas is supplied from the nitrogen-containing gas supply source 131b into the processing chamber S, thereby forming the BN film 13 on the underlayer 12. As the boron-containing gas, for example, a borane-based gas such as B2H6, BCl3, or a gas obtained by diluting these gases with H2, N2, or the like can be used. As the nitrogen-containing gas, for example, one or more gases selected from the group consisting of NH3, N2H2, N2H4, and organic hydrazine compounds such as CH3(NH)NH2 can be used. The temperature of the substrate W when forming the BN film 13 may be, for example, 250°C to 400°C.

[0029] In the step S3 of forming the B-Si film, as shown in FIG. 3(c), the B-Si film 14 is formed on the BN film 13 by, for example, thermal CVD. In this embodiment, the boron-containing gas is supplied from the boron-containing gas supply source 131a into the processing chamber S, and the silicon-containing gas is supplied from the silicon-containing gas supply source 131c into the processing chamber S, thereby forming the B-Si film 14 on the BN film 13. As the boron-containing gas, for example, the same type of gas as the boron-containing gas used in the step S2 of forming the BN film can be used. However, as the boron-containing gas, for example, a gas different from the boron-containing gas used in the step S2 of forming the BN film can be used. As the silicon-containing gas, for example, one or more gases selected from the group consisting of SiH4, Si2H6, HCD, DCS, hexaethylaminodisilane, HMDS, TCS, DSA, TSA, and BTBAS can be used. The temperature of the substrate W when forming the B-Si film may be, for example, 250° C. to 400° C.

[0030] After forming the B-Si film with a desired thickness, the processing chamber S is evacuated by the exhaust device 107, and an inert gas is supplied from the inert gas supply source 131d to the processing chamber S to purge the processing chamber S. As the inert gas, for example, a rare gas such as N2 gas or Ar gas can be used. Then, the processing chamber S is returned to atmospheric pressure, and the boat 112 is lowered to unload the substrate W.

[0031] Incidentally, the adhesion between a substrate and a film depends on the hydrogen (H) concentration of the film. For example, as shown in FIG. 4, when the H concentration of the film formed on the substrate W is high, in addition to the covalent bond (shown by the dashed line in FIG. 4) between the substrate and the film, a bond due to an intermolecular force (shown by the dashed line in FIG. 4) occurs, and therefore, it is considered that the adhesion between the substrate W and the film F is weakened. In FIG. 4, X represents an element (e.g., Si) on the surface of the substrate W. For example, the H concentration of the B-Si film 14 formed in the above-mentioned step S3 for forming the B-Si film is relatively high (about 10% to 20%), so when the B-Si film 14 is formed on the base 12, the adhesion between the base 12 and the B-Si film 14 is likely to be weakened.

[0032] In contrast, according to the film forming method of the embodiment, a BN film 13 is formed on a base 12, and then a B-Si film 14 is formed on the BN film 13. The BN film 13 is found to be 50% B and 50% N by elemental analysis, and is a film that does not contain or contains very little hydrogen (H) in the film. That is, according to the film forming method of the embodiment, when forming the B-Si film 14 on the base 12, a BN film 13 that does not contain or contains very little H in the film is inserted between the base 12 and the B-Si film 14. This makes it possible to form a B-Si film 14 with good adhesion.

[0033] Furthermore, according to the film forming method of the embodiment, there is no or only a small temperature difference between the film forming temperature in the step S2 for forming the BN film and the step S3 for forming the B-Si film. This improves productivity by shortening the time required for changing the temperature when the step S2 for forming the BN film and the step S3 for forming the B-Si film are performed in the same processing chamber S. Also, peeling of the B-Si film accumulated on the dummy substrate can be suppressed.

[0034] [Application example of B-Si film] An application example of the B-Si film formed by the film forming method of the embodiment will be described with reference to Fig. 5. Fig. 5 is a diagram showing a part of the manufacturing process of a semiconductor device using the B-Si film, and shows a part of the manufacturing process of a DRAM (Dynamic Random Access Memory).

[0035] As shown in Fig. 5, the B-Si film formed by the film forming method of the embodiment is used as a hard mask 23 when etching an interlayer insulating film 21 to form a capacitor hole 22 in, for example, a DRAM manufacturing process. The formation of the capacitor hole 22 requires a technique for etching a hole with a very large aspect ratio (depth / hole diameter). In the example of Fig. 5, the interlayer insulating film 21 is a laminated film of a SiO2 film 21a and a SiN film 21b.

[0036] Conventionally, an amorphous silicon (a-Si) film is used as the hard mask 23, but the a-Si film may also be slightly etched when etching the interlayer insulating film 21. If the aspect ratio of the capacitor hole 22 increases, the a-Si film is exposed to the etching gas for a longer period of time, and the amount of etching increases. Therefore, the a-Si film is made thicker to maintain its function as the hard mask 23.

[0037] In contrast, the B-Si film formed by the film formation method of the embodiment has a higher selectivity to the interlayer insulating film 21 than the a-Si film, and therefore the hard mask 23 can be made thinner. In addition, in the film formation method of the embodiment, a BN film is formed on the underlayer (interlayer insulating film 21), and then a B-Si film is formed on the BN film as the hard mask 23, so that a B-Si film with good adhesion can be formed. Thus, according to the film formation method of the embodiment, a B-Si film with a thin film thickness and good adhesion to the underlayer can be provided as the hard mask 23 used in the manufacturing process of a DRAM.

[0038] [Example] First, an example in which the adhesion of the B-Si film formed by the film forming method of the embodiment was evaluated will be described. In the example, a silicon wafer with a SiN film formed on its surface and a silicon wafer with a SiCN film formed on its surface were prepared. Next, a BN film and a B-Si film were successively formed on the SiN film and the SiCN film under a vacuum atmosphere by the above-mentioned processing apparatus 100. Next, the silicon wafer with the B-Si film formed thereon was heat-treated at 550° C. for 30 minutes.

[0039] The conditions for forming the BN film are as follows.

[0040] 10% B2H6 / H2 gas flow rate: 700sccm NH3 gas flow rate: 100sccm Film forming temperature: 300℃ Pressure inside the processing chamber: 0.5 Torr (66.7 Pa) Film thickness: 20 nm

[0041] The deposition conditions for the B-Si film are as follows.

[0042] 10%B2H6 / H2 gas flow rate: 800sccm SiH4 gas flow rate: 666sccm Film forming temperature: 250℃ Pressure inside the processing chamber: 0.5 Torr (66.7 Pa) Film thickness: 580nm

[0043] Next, the adhesion of each B-Si film was evaluated by a tape test before and after the silicon wafer was heat-treated. In the tape test, first, a cutter knife 603 was used to make a checkerboard pattern of cuts penetrating the B-Si film 602 and reaching the silicon wafer 601 (see Fig. 6(a) and Fig. 6(b)). The interval L between adjacent cuts was 2 mm, and the angle of the cutter knife 603 when making the cuts was 35 degrees to 45 degrees with respect to the B-Si film 602. Next, as shown in Fig. 6(c), a cellophane adhesive tape 604 was attached to the cut B-Si film 602, and the end of the cellophane adhesive tape 604 was held and pulled in the direction of the arrow A, and the presence or absence of peeling of the B-Si film 602 was observed.

[0044] Comparative Example 1, which was carried out for comparison, will now be described. In Comparative Example 1, a silicon wafer having a SiN film formed on its surface and a silicon wafer having a SiCN film formed on its surface were prepared. Then, a B-Si film was formed under the same conditions as in the embodiment, using the processing apparatus 100 described above, without forming a BN film on the SiN film or the SiCN film. Then, the silicon wafer having the B-Si film formed thereon was heat-treated at 550°C for 30 minutes. Also, before and after the heat treatment of the silicon wafer, the adhesion of each B-Si film was evaluated by the same tape test as in the embodiment.

[0045] Comparative Example 2, which was carried out for comparison, will be described. In Comparative Example 2, a silicon wafer with a SiN film formed on its surface and a silicon wafer with a SiCN film formed on its surface were prepared. Next, an a-Si film and a B-Si film were successively formed on the SiN film and the SiCN film under a vacuum atmosphere by the above-mentioned processing apparatus 100. Next, the silicon wafer with the B-Si film formed thereon was heat-treated at 550°C for 30 minutes. In addition, before and after the heat treatment of the silicon wafer, the adhesion of each B-Si film was evaluated by the same tape test as in the embodiment. The a-Si film was formed to a thickness of 20 nm by supplying SiH4 gas while the silicon wafer was heated to 470°C. In addition, the film formation conditions of the B-Si film were the same as in the embodiment.

[0046] 7 to 9 are diagrams showing the evaluation results of the adhesion of the B-Si film, and show the results of the example, the comparative example 1, and the comparative example 2, respectively.

[0047] As shown in FIG. 7, in the embodiment in which the BN film and the B-Si film were successively formed on the underlayer under a vacuum atmosphere, it was confirmed that the B-Si film did not peel off both before and after the heat treatment, regardless of whether the underlayer was a SiN film or a SiCN film.

[0048] In contrast, as shown in FIG. 8, in Comparative Example 1 in which a B-Si film was formed without forming a BN film on a base, peeling of the B-Si film was confirmed both before and after heat treatment, regardless of whether the base was a SiN film or a SiCN film.

[0049] 9, in Comparative Example 2 in which an s-Si film and a B-Si film were successively formed on a base under a vacuum atmosphere, when the base was a SiN film, there was no peeling of the B-Si film before the heat treatment, but peeling of the B-Si film occurred at the beveled portion after the heat treatment. Also, in Comparative Example 2, when the base was a SiCN film, there was no peeling of the B-Si film both before and after the heat treatment.

[0050] The above results show that by successively forming a BN film and a B-Si film on a substrate under a vacuum atmosphere, a B-Si film with good adhesion can be formed on the substrate regardless of the type of substrate.

[0051] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0052] In the above embodiment, the processing apparatus is a batch type apparatus that processes a plurality of substrates at once, but the present disclosure is not limited thereto. For example, the processing apparatus may be a single-wafer type apparatus that processes substrates one by one. Also, for example, the processing apparatus may be a semi-batch type apparatus that processes substrates by rotating a plurality of substrates arranged on a turntable in a processing vessel by the turntable, and passing the substrates through an area where a first gas is supplied and an area where a second gas is supplied in sequence. [Explanation of symbols]

[0053] 100 Processing equipment 130 Processing gas supply unit 150 Control section S Processing Room

Claims

1. A method for manufacturing a substrate, comprising: supplying a first process gas, the first process gas including a boron-containing gas, a nitrogen-containing gas, and a hydrogen gas, to a substrate; and forming a boron nitride film on the substrate; supplying a second process gas containing the boron-containing gas, the silicon-containing gas, and hydrogen gas to the substrate to form a boron-containing silicon film on the boron nitride film; The film forming method includes the steps of:

2. the step of forming the boron nitride film and the step of forming the boron-containing silicon film are performed successively under a vacuum atmosphere; The film forming method according to claim 1 .

3. the step of forming the boron nitride film and the step of forming the boron-containing silicon film are performed successively in the same processing chamber; The film forming method according to claim 1 or 2.

4. The boron-containing gas is B2H6 gas, The nitrogen-containing gas is NH 3 gas. The film forming method according to claim 1 .

5. The boron-containing gas is B2H6 gas, The silicon-containing gas is SiH 4 gas; The film forming method according to claim 1 .

6. Before the step of forming the boron nitride film, a step of preparing the substrate having a SiN film or a SiCN film formed on a surface thereof is included. The film forming method according to claim 1 .

7. The boron nitride film is formed while the substrate is heated to 250° C. to 400° C. The film forming method according to claim 1 .

8. a processing chamber for processing a substrate; a processing gas supply unit for supplying a processing gas to the processing chamber; A control unit; Equipped with The control unit is supplying a first process gas containing a boron-containing gas, a nitrogen-containing gas, and a hydrogen gas into the process chamber to form a boron nitride film on the substrate accommodated in the process chamber; supplying a second process gas containing the boron-containing gas, the silicon-containing gas, and hydrogen gas into the process chamber to form a boron-containing silicon film on the boron nitride film; and configured to control the process gas supply to perform Processing unit.

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