Embedding method and film forming apparatus

Abstract

To provide a technology that can form a metal oxide film with high quality and excellent embedding characteristics.SOLUTION: An embedding method for embedding a metal oxide film into a recess formed on the surface of a substrate includes the steps of depositing the metal oxide film by supplying a metal source gas and an oxidant into the recess and etching a portion of the metal oxide film by supplying an etching gas including at least one of SOCl2 and (COCl)2 to the metal oxide film.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] A technique is known for forming an aluminum-containing oxide thin film by atomic layer deposition using an aluminum-containing composition containing trimethylaluminum and dimethylaluminum hydride and an oxygen-containing compound containing oxygen atoms as raw materials (see, for example, Patent Document 1). Also known is a technique for removing the Al2O3 film from the reactor surface by reacting an Al2O3 film covering the reactor surface with BCl3 and COCl2 to produce a volatile product, and removing the volatile product from the reactor (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-141882 A [Patent Document 2] JP 2005-175466 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique capable of forming a high-quality metal oxide film with excellent filling properties. [Means for solving the problem]

[0005] A method for embedding according to one aspect of the present disclosure includes: A method for embedding a metal oxide film in a recess formed on a surface of a substrate, the method comprising the steps of: loading the substrate into a processing vessel; supplying a metal source gas and an oxidizing agent into the processing vessel to form the metal oxide film in the recess and on an inner wall of the processing vessel; and depositing SOCl on the metal oxide film. 2 and (COCl) 2 and a step of etching a part of the metal oxide film by supplying an etching gas containing at least one of the above. In the etching step, the substrate is heated to 500° C. or higher, and in the etching step, the metal oxide film formed in the recess is selectively etched with respect to the metal oxide film formed on the inner wall of the processing vessel. . Effect of the Invention

[0006] According to the present disclosure, a high-quality metal oxide film with excellent filling properties can be formed. [Brief description of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view showing an example of a process of a filling method according to an embodiment of the present invention; [Diagram 2] 5A to 5C are cross-sectional views showing another example of the embedding method according to the embodiment; [Diagram 3] FIG. 1 is a schematic cross-sectional view showing an example of a film forming apparatus for carrying out a filling method according to an embodiment. 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] [Metal oxide film] There is a need to fill recesses with high-quality metal oxide films. High-quality metal oxide films are formed by high-temperature processes, for example at temperatures of 500° C. or higher. However, high-temperature processes tend to deteriorate the step coverage of recesses, resulting in poor filling characteristics.

[0010] Therefore, the present inventors have intensively studied a method for forming a high-quality metal oxide film with excellent filling properties. As a result, they have found that a high-quality metal oxide film with excellent filling properties can be formed by a filling method including a step of forming a metal oxide film and a step of etching a part of the metal oxide film with thionyl chloride [SOCl2] and / or oxalyl chloride [(COCl)2]. The details are described below.

[0011] [Embedding method] An example of the embedding method of the embodiment will be described with reference to Fig. 1. The embedding method of the embodiment is a method for embedding an aluminum oxide film (Al2O3 film) in a recess formed on a surface of a substrate by repeating a cycle including a film forming step and an etching step.

[0012] In the film formation process, as shown in FIG. 1(a), an Al source gas and an oxidizing agent are supplied to a recess 110 formed on the surface of a substrate 100 to form an Al2O3 film 120. The substrate 100 may be, for example, a semiconductor wafer such as a silicon wafer. The recess 110 may be, for example, a trench or a via. In the film formation process, the Al2O3 film 120 is formed so that the opening of the recess 110 is not blocked. In the film formation process, it is preferable to form the Al2O3 film 120 by atomic layer deposition (ALD). That is, in the film formation process, it is preferable to form the Al2O3 film 120 in the recess 110 by repeating the supply of an Al source gas, the supply of a purge gas, the supply of an oxidizing agent, and the supply of a purge gas in this order. This allows the Al2O3 film 120 to be conformally formed in the recess 110, so that voids, seams, and the like are unlikely to occur when the Al2O3 film 120 is filled in the recess 110. Furthermore, in the film formation process, it is preferable to heat the substrate to a high temperature of 500°C or higher. This allows a high-quality Al2O3 film 120 to be formed. In film formation by ALD, which is performed with the substrate heated to a temperature of 500°C or higher, the Al source gas can be, for example, AlCl3, (CH3)3Al2Cl3, EADC[(CH3CH2)AlCl2], DEAC[(CH3CH2)2AlCl], EASC[(CH3CH2) 1.5 AlCl 1.5 ], DMAC[(CH3)2AlCl], or other halogen-containing Al source gases can be used. As the oxidizing agent, for example, O2 gas, O3 gas, H2O gas, H2O2 gas, a mixed gas of H2 and O2, or IPA (isopropyl alcohol) gas can be used. As the purge gas, inert gases such as N2 gas and Ar gas can be used.

[0013] For example, when DMAC [(CH3)2AlCl] is used as the Al source gas and H2O gas is used as the oxidizing gas, the Al2O3 film 120 is formed by the chemical reaction represented by the following formula (A).

[0014] (CH3)2AlCl+H2O→Al2O3(s)+CH4(g)+HCl(g) (A)

[0015] In the etching process, as shown in FIG. 1(b), an etching gas containing at least one of thionyl chloride [SOCl2] and oxalyl chloride [(COCl)2] is supplied to the Al2O3 film 120 to etch a part of the Al2O3 film 120. For example, in the etching process, the Al2O3 film 120 is selectively etched so as to widen the opening of the recess 110. In the etching process, it is preferable to heat the substrate to the same temperature as in the film formation process or to a temperature approximately the same as that in the film formation process, for example, a high temperature of 500° C. or higher. Approximately the same temperature means a temperature within a range of ±5% from the same temperature. SOCl2 and (COCl)2 have an etching rate of 1 nm / min to 100 nm / min for the Al2O3 film 120 at a temperature of 500° C. or higher. Therefore, by using SOCl2 and (COCl)2 as the etching gas, a part of the Al2O3 film 120 can be etched with good controllability without changing the processing temperature in the film formation process and the etching process. Thus, in the etching process, it is preferable to use an etching gas that provides an etching rate of 1 nm / min to 100 nm / min for the Al2O3 film 120 at a temperature of 500°C or higher. It is more preferable to use an etching gas that provides an etching rate of 5 nm / min to 50 nm / min. Also, SOCl2 and (COCl)2 have a low etching rate for the Al2O3 film 120 at a temperature of less than 500°C. Therefore, the film deposited on the inner wall of the processing vessel, which is at a lower temperature than the substrate, is hardly etched, and the generation of particles due to peeling of the deposited film from the inner wall of the processing vessel can be suppressed. For example, when SOCl2 gas is used as the etching gas, a part of the Al2O3 film 120 can be etched by a chemical reaction represented by the following formula (B).

[0016] Al2O3+SOCl2→AlCl3(g)+SO2(g) (B)

[0017] According to the filling method of the embodiment described above, a cycle including a film forming step and an etching step is repeated in the recess 110 formed on the surface of the substrate 100, so that the Al2O3 film 120 is filled in the recess 110. In the etching step, an etching gas including at least one of SOCl2 and (COCl)2 is supplied to the Al2O3 film 120 to etch a part of the Al2O3 film. This makes it possible to form a high-quality metal oxide film with excellent filling properties.

[0018] Although the case where the Al2O3 film 120 is embedded in the recess 110 consisting only of a vertical hole has been described above with reference to Fig. 1, the present disclosure is not limited thereto. For example, as shown in Fig. 2, the embedding method of the embodiment can also be applied to a case where a recess 210 formed in a surface of a substrate 200 includes a vertical hole 211 extending in the thickness direction of the substrate 200 and a lateral hole 212 extending from a side wall 211a of the vertical hole 211 in a direction parallel to the surface of the substrate 200.

[0019] Specifically, in the film forming step, as shown in Fig. 2(a), an Al source gas and an oxidizing agent are supplied to a recess 210 formed on the surface of a substrate 200 to form an Al2O3 film 220. In the etching step, as shown in Fig. 2(b), an etching gas containing at least one of thionyl chloride [SOCl2] and oxalyl chloride [(COCl)2] is supplied to the Al2O3 film 220 to etch a part of the Al2O3 film 220. Then, by repeating a cycle including the film forming step and the etching step, the Al2O3 film 220 can be embedded in the recess 210.

[0020] [Film forming equipment] An example of a film formation apparatus for carrying out the filling method of the embodiment will be described with reference to Fig. 3. The film formation apparatus of the embodiment is configured as an apparatus capable of carrying out film formation by atomic layer deposition (ALD) method and film formation by chemical vapor deposition (CVD) method.

[0021] The film forming apparatus includes a processing chamber 1, a mounting table 2, a shower head 3, an exhaust unit 4, a gas supply unit 5, a control unit 6, and the like.

[0022] The processing vessel 1 is made of a metal such as aluminum and has a substantially cylindrical shape. The processing vessel 1 accommodates a substrate W therein. The substrate W may be, for example, a semiconductor wafer. A side wall of the processing vessel 1 is provided with a loading / unloading port 11 for loading or unloading the substrate W. The loading / unloading port 11 is opened and closed by a gate valve 12. An annular exhaust duct 13 having a rectangular cross section is provided on the main body of the processing vessel 1. A slit 13a is formed along the inner peripheral surface of the exhaust duct 13. An exhaust port 13b is formed on the outer wall of the exhaust duct 13. A ceiling wall 14 is provided on the upper surface of the exhaust duct 13 so as to close the upper opening of the processing vessel 1. The space between the exhaust duct 13 and the ceiling wall 14 is airtightly sealed by a seal ring 15.

[0023] The mounting table 2 horizontally supports the substrate W in the processing chamber 1. The mounting table 2 has a disk shape larger than the substrate W and is made of a ceramic material such as aluminum nitride (AlN) or a metal material such as an aluminum or nickel alloy. A heater 21 for heating the substrate W is embedded inside the mounting table 2. The heater 21 generates heat when powered by a heater power supply (not shown). The output of the heater 21 is controlled by a temperature signal from a thermocouple (not shown) provided near the upper surface of the mounting table 2, thereby controlling the substrate W to a predetermined temperature. The mounting table 2 is provided with a cover member 22 made of ceramics such as alumina so as to cover the outer circumferential region of the upper surface and the side surfaces.

[0024] The mounting table 2 is supported by a support member 23. The support member 23 extends from the center of the bottom surface of the mounting table 2 to below the processing vessel 1 through a hole formed in the bottom wall of the processing vessel 1, and its lower end is connected to a lifting mechanism 24. The mounting table 2 is raised and lowered by the lifting mechanism 24 between a processing position shown in FIG. 3 and a transfer position shown by a two-dot chain line below the processing position where the substrate W can be transferred. A flange 25 is attached to the support member 23 below the processing vessel 1. A bellows 26 is provided between the bottom surface of the processing vessel 1 and the flange 25. The bellows 26 separates the atmosphere inside the processing vessel 1 from the outside air, and expands and contracts with the lifting and lowering operation of the mounting table 2.

[0025] Three wafer support pins 27 (only two shown) are provided near the bottom surface of the processing vessel 1 so as to protrude upward from a lift plate 27a. The wafer support pins 27 are raised and lowered via the lift plate 27a by a lift mechanism 28 provided below the processing vessel 1. The wafer support pins 27 are inserted into through holes 2a provided in the mounting table 2 at the transfer position, and can be protruded and retracted from the upper surface of the mounting table 2. The substrate W is transferred between a transfer robot (not shown) and the mounting table 2 by raising and lowering the wafer support pins 27.

[0026] The shower head 3 supplies a processing gas into the processing chamber 1 in a shower-like manner. The shower head 3 is made of, for example, a metal material, and is disposed facing the mounting table 2. The shower head 3 has approximately the same diameter as the mounting table 2. The shower head 3 includes a main body 31 and a shower plate 32. The main body 31 is fixed to the lower surface of the ceiling wall 14. The shower plate 32 is connected below the main body 31. A gas diffusion space 33 is formed between the main body 31 and the shower plate 32. A gas introduction hole 36 is provided in the gas diffusion space 33 so as to penetrate through the center of the ceiling wall 14 and the main body 31. A ring-shaped protrusion 34 protruding downward is formed on the periphery of the shower plate 32. A large number of gas discharge holes 35 are formed on the flat surface on the inner side of the ring-shaped protrusion 34 of the shower plate 32.

[0027] When the mounting table 2 is moved to the processing position, a processing space 37 is formed between the mounting table 2 and the shower plate 32, and the upper surface of the cover member 22 and the annular protrusion 34 are adjacent to each other to form an annular gap 38.

[0028] The exhaust unit 4 exhausts the inside of the processing vessel 1. The exhaust unit 4 includes an exhaust pipe 41 and an exhaust mechanism 42. The exhaust pipe 41 is connected to the exhaust port 13b. The exhaust mechanism 42 is connected to the exhaust pipe 41 and includes a vacuum pump, a pressure control valve, etc. The exhaust mechanism 42 exhausts gas inside the processing vessel 1 via the exhaust duct 13 and the exhaust pipe 41.

[0029] The gas supply unit 5 supplies various gases to the shower head 3. The gas supply unit 5 includes a gas source 51 and a gas line 52. The gas source 51 includes, for example, various process gas supply sources, a mass flow controller, and a valve (none of which are shown). The various process gases include an Al source gas, an oxidizing agent, and an etching gas used in the filling method of the above-mentioned embodiment. The various gases are introduced from the gas source 51 through the gas line 52 and the gas introduction hole 36 into the gas diffusion space 33.

[0030] The control unit 6 controls each part of the film forming apparatus to implement, for example, the above-mentioned embedding method. The control unit 6 may be, for example, a computer. In addition, a computer program for operating each part of the film forming apparatus is stored in a storage medium. The storage medium may be, for example, a flexible disk, a compact disk, a hard disk, a flash memory, a DVD, or the like.

[0031] Next, an example of the operation of the film forming apparatus will be described in the case where the filling method according to the embodiment shown in FIGS.

[0032] First, the control unit 6 opens the gate valve 12 and causes the transfer mechanism (not shown) to transfer the substrate W having a recess on its surface into the processing vessel 1 and place it on the mounting table 2. The substrate W is placed horizontally with its surface facing up. The control unit 6 retracts the transfer mechanism from inside the processing vessel 1, and then closes the gate valve 12. Next, the control unit 6 heats the substrate W to a predetermined temperature using the heater 21 of the mounting table 2, and adjusts the inside of the processing vessel 1 to a predetermined pressure using the exhaust mechanism 42.

[0033] Next, the control unit 6 controls each part of the film forming apparatus to implement the filling method of the above-mentioned embodiment. That is, the control unit 6 controls the exhaust unit 4, the gas supply unit 5, etc., and repeats a cycle including the film forming step and the etching step to fill the recess with the Al2O3 film.

[0034] After the Al2O3 film is embedded in the recesses formed on the surface of the substrate W, the control unit 6 unloads the substrate W from the processing chamber 1 in a reverse order to the loading procedure of the substrate W into the processing chamber 1.

[0035] In the above embodiment, the Al source gas is an example of a metal source gas, and the Al2O3 film is an example of a metal oxide film.

[0036] 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.

[0037] In the above embodiment, the case where an Al2O3 film is formed as the metal oxide film has been described, but the present disclosure is not limited thereto. For example, the metal oxide film may be a high-k film such as an HfO2 film or a ZrO2 film. For example, when forming an HfO2 film, HfCl4 can be used as the metal source gas. Also, for example, when forming a ZrO2 film, ZrCl4 gas can be used as the metal source gas. SOCl2 and (COCl)2 have an etching rate of 1 nm / min to 100 nm / min for HfO2 film and ZrO2 film at a temperature of 500° C. or higher. Therefore, by using SOCl2 and (COCl)2 as the etching gas, a part of the HfO2 film and the ZrO2 film can be etched with good controllability without changing the processing temperature of the film formation process and the etching process, as in the case of an Al2O3 film.

[0038] In the above embodiment, the case where thionyl chloride [SOCl2] and oxalyl chloride [(COCl)2] are used as the etching gas is described, but the present disclosure is not limited thereto. For example, Cl2 gas, BCl3 gas, and ClF3 gas can be used as the etching gas.

[0039] In the above embodiment, the case where the film forming apparatus is a single-wafer type apparatus that processes substrates one by one has been described, but the present disclosure is not limited thereto. For example, the film forming apparatus may be a batch type apparatus that processes multiple substrates at once. Also, for example, the film forming apparatus may be a semi-batch type apparatus that processes the substrates by rotating multiple 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.

[0040] In the above embodiment, the film forming apparatus does not have a plasma generating unit, but the present disclosure is not limited to this. For example, the film forming apparatus may have a plasma generating unit. [Explanation of symbols]

[0041] 1 Processing vessel 5 Gas supply section 6. Control Unit

Claims

1. A method for filling a recess formed on a surface of a substrate with a metal oxide film, comprising the steps of: loading the substrate into a processing chamber; supplying a metal source gas and an oxidizing agent into the processing vessel to form the metal oxide film on the recess and an inner wall of the processing vessel; The metal oxide film is then coated with SOCl. ２ and (COCl) ２ supplying an etching gas containing at least one of the above to etch a portion of the metal oxide film; having In the etching step, the substrate is heated to 500° C. or higher; In the etching step, the metal oxide film formed in the recess is selectively etched relative to the metal oxide film formed on the inner wall of the processing vessel. Embedding method.

2. A method for filling a recess formed on a surface of a substrate with a metal oxide film, comprising the steps of: loading the substrate into a processing chamber; supplying a metal source gas and an oxidizing agent into the processing vessel to form the metal oxide film on the recess and an inner wall of the processing vessel; The metal oxide film is then coated with SOCl. ２ and (COCl) ２ supplying an etching gas containing at least one of the above to etch a portion of the metal oxide film; having the metal oxide film is an aluminum oxide film, In the etching step, the substrate is heated to 500° C. or higher; In the etching step, the metal oxide film formed in the recess is selectively etched relative to the metal oxide film formed on the inner wall of the processing vessel. Embedding method.

3. The deposition step and the etching step are performed at the same or substantially the same temperature. The embedding method according to claim 1 or 2.

4. repeating the film forming step and the etching step; The embedding method according to any one of claims 1 to 3.

5. In the film forming step and the etching step, the substrate is heated to 500° C. or higher. The embedding method according to any one of claims 1 to 4.

6. In the film forming step, the metal oxide film is formed by atomic layer deposition. The embedding method according to any one of claims 1 to 5.

7. The recess includes a vertical hole extending in a thickness direction of the substrate. The embedding method according to any one of claims 1 to 6.

8. The recess includes a lateral hole extending from a side wall of the vertical hole in a direction parallel to a surface of the substrate. The embedding method according to claim 7.

9. The metal oxide film is a high-k film. The embedding method according to any one of claims 1 to 8.

10. The metal source gas contains a metal and a halogen. The embedding method according to any one of claims 1 to 9.

11. the metal is aluminum; The metal oxide film is an aluminum oxide film. The embedding method according to claim 10.

12. A processing vessel; a gas supply unit for supplying a metal source gas, an oxidizing agent, and an etching gas into the processing chamber; A control unit; Equipped with The etching gas is SOCl ２ and (COCl) ２ At least one of The control unit is placing a substrate having a recess formed on a surface thereof in the processing vessel; supplying the metal source gas and the oxidizing agent into the processing vessel to form a metal oxide film on the recess and an inner wall of the processing vessel; The metal oxide film is then coated with SOCl. ２ and (COCl) ２ supplying an etching gas containing at least one of the above to etch a portion of the metal oxide film; and configured to control the gas supply to perform In the etching step, the substrate is heated to 500° C. or higher; In the etching step, the metal oxide film formed in the recess is selectively etched relative to the metal oxide film formed on the inner wall of the processing vessel. Film deposition equipment.

13. A processing vessel; a gas supply unit for supplying a metal source gas, an oxidizing agent, and an etching gas into the processing chamber; A control unit; Equipped with The etching gas is SOCl ２ and (COCl) ２ At least one of The control unit is placing a substrate having a recess formed on a surface thereof in the processing vessel; supplying the metal source gas and the oxidizing agent into the processing vessel to form a metal oxide film on the recess and an inner wall of the processing vessel; The metal oxide film is then coated with SOCl. ２ and (COCl) ２ supplying an etching gas containing at least one of the above to etch a portion of the metal oxide film; and configured to control the gas supply to perform the metal oxide film is an aluminum oxide film, In the etching step, the substrate is heated to 500° C. or higher; In the etching step, the metal oxide film formed in the recess is selectively etched relative to the metal oxide film formed on the inner wall of the processing vessel. Film deposition equipment.

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