Substrate processing method and substrate processing apparatus

Abstract

The invention relates to a substrate processing method and a substrate processing apparatus. Provided is a technique capable of adjusting an in-plane distribution of an etching amount. A substrate processing method according to one embodiment of the present disclosure includes: a step (a) of preparing a substrate having a silicon oxide film on a surface thereof; (b) supplying a first gas, which contains hydrogen fluoride gas and does not contain alkaline gas, to the surface of the substrate; and a step (c) in which, after the step (b), a second gas containing a hydrogen fluoride gas and a basic gas is supplied to the surface of the substrate.

Description

Technical Field

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

[0002] A technique for etching a silicon oxide film using a mixed gas of hydrogen fluoride gas and ammonia gas is known (for example, refer to Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2004-343094 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] The present disclosure provides a technology capable of adjusting the in-plane distribution of an etching amount.

[0008] Solutions for solving problems

[0009] A substrate processing method according to one embodiment of the present invention comprises the following steps: step (a), preparing a substrate having a silicon oxide film on its surface; step (b), supplying a first gas containing hydrogen fluoride gas and not containing alkaline gas to the surface of the substrate; and step (c), after step (b), supplying a second gas containing hydrogen fluoride gas and alkaline gas to the surface of the substrate.

[0010] Effects of the Invention

[0011] According to the present disclosure, it is possible to adjust the in-plane distribution of the etching amount. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 1 is a flowchart showing a substrate processing method according to an embodiment.

[0013] Figure 2 It is a cross-sectional view showing an example of a substrate.

[0014] Figure 3 This is a diagram showing the surface reaction when the HF supply process is performed before the COR process.

[0015] Figure 4 It is a diagram showing the surface reaction when the HF supply process is not performed before the COR process.

[0016] Figure 5 It is a cross-sectional view showing a substrate processing apparatus according to an embodiment.

[0017] Figure 6This is a diagram showing the results of measuring the in-plane distribution of the etching amount of the silicon oxide film.

[0018] Figure 7 This is a diagram showing the results of measuring the in-plane distribution of the etching amount of the silicon nitride film. DETAILED DESCRIPTION

[0019] Hereinafter, non-limiting exemplary embodiments of the present disclosure will be described with reference to the attached drawings. In all the attached drawings, the same or corresponding components or parts are marked with the same or corresponding reference numerals, and repeated descriptions are omitted.

[0020] 〔Etching of silicon oxide film〕

[0021] A technique for etching a silicon oxide film formed on a surface of a substrate by chemical oxide removal (COR) is known. In the COR process, a mixed gas of hydrogen fluoride (HF) gas and ammonia (NH 3 ) gas is supplied to the silicon oxide film to etch the silicon oxide film.

[0022] The etching of silicon oxide film by COR treatment is a highly reactive process. Therefore, when the mixed gas of hydrogen fluoride gas and ammonia gas is supplied from the periphery of the substrate along the surface of the substrate, the etching amount of the silicon oxide film at the periphery of the substrate is sometimes greater than the etching amount of the silicon oxide film at the center of the substrate, and the in-plane uniformity of the etching amount deteriorates. It is believed that this is because the hydrogen fluoride gas and ammonia gas react with the silicon oxide film at the periphery of the substrate before reaching the center of the substrate and are consumed.

[0023] When the COR treatment time is increased, the center of the substrate is gradually easier to be etched than the peripheral part, and the in-plane uniformity is improved. However, when the etching time is increased, the etching amount of the silicon oxide film increases. Therefore, it is difficult to improve the in-plane uniformity of the etching amount of the silicon oxide film with a small etching amount.

[0024] When a silicon nitride film is formed as a hard mask on the surface of the substrate, it is required that the silicon nitride film is not etched or is hardly etched when the silicon oxide film is etched. However, when the COR treatment time is prolonged, the silicon nitride film is easily etched.

[0025] The inventors of the present invention have found that by supplying a first gas containing hydrogen fluoride gas and no alkaline gas to the surface of the substrate before performing COR treatment, the in-plane distribution of the etching amount of the silicon oxide film can be adjusted with a small etching amount. The substrate processing method and substrate processing apparatus according to the embodiment are described below.

[0026] 〔Substrate processing method〕

[0027] Reference Figure 1 and Figure 2 A substrate processing method according to an embodiment will be described. Figure 1 1 is a flowchart showing a substrate processing method according to an embodiment. Figure 2 1 is a cross-sectional view showing an example of the substrate 100 .

[0028] like Figure 1 As shown, the substrate processing method according to the embodiment includes a preparation step S10 , an HF supply step S20 , a COR step S30 , and a PHT step S40 .

[0029] like Figure 2 As shown, the preparation step S10 includes preparing a substrate 100 having a silicon nitride film 102 and a silicon oxide film 103 on the surface. The silicon nitride film 102 and the silicon oxide film 103 are formed on a base substrate 101. The base substrate 101 is, for example, a silicon wafer. The silicon oxide film 103 is, for example, a thermal oxide film formed by thermal oxidation treatment. The preparation step S10 may include adjusting and maintaining the substrate 100 at a predetermined temperature. The predetermined temperature may be the same temperature as the first processing temperature described later. In this case, the temperature may not be changed when transferring from the preparation step S10 to the HF supply step S20. Therefore, productivity is improved.

[0030] The HF supply process S20 is performed after the preparation process S10. The HF supply process S20 includes supplying a first gas containing hydrogen fluoride gas and not containing alkaline gas to the surface of the substrate 100. When the hydrogen fluoride gas is supplied to the surface of the substrate 100, the silicon oxide film 103 reacts with the hydrogen fluoride gas and generates silicon tetrafluoride (SiF4). In the case where there is a natural oxide film on the silicon nitride film 102, the natural oxide film reacts with the hydrogen fluoride gas and is etched. The first gas may also include an inactive gas such as nitrogen (N2) gas. The first gas is, for example, a mixed gas of hydrogen fluoride gas and nitrogen gas. The HF supply process S20 may include adjusting and maintaining the substrate 100 to a first processing temperature. The first processing temperature is, for example, the same as the second processing temperature described later.

[0031] The COR process S30 is performed after the HF supply process S20. The COR process S30 includes a COR process in which etching is performed chemically without generating plasma to at least transform the surface layer of the silicon oxide film 103 into a reaction product. The COR process S30 includes supplying a second gas containing hydrogen fluoride gas and an alkaline gas to the surface of the substrate 100. When the hydrogen fluoride gas and the alkaline gas are supplied to the surface of the substrate 100, the silicon oxide film 103 reacts with the hydrogen fluoride gas and the alkaline gas and generates ammonium fluorosilicate [(NH4)2SiF6]. The alkaline gas is, for example, ammonia. The alkaline gas may also be hydrazine (N2H4) gas. The second gas may also further include an inactive gas such as nitrogen. The second gas is, for example, a mixed gas of hydrogen fluoride gas, ammonia and nitrogen.

[0032] The COR process S30 can be continuously performed in a state where the supply of hydrogen fluoride gas is continued after the HF supply process S20. In other words, the COR process S30 can be performed without performing a purge process after the HF supply process S20. In this case, the COR process S30 can be performed without causing silicon tetrafluoride generated on the surface of the substrate 100 in the HF supply process S20 to be separated from the surface of the substrate 100.

[0033] The COR process S30 may include maintaining the temperature of the substrate 100 at a second processing temperature. The second processing temperature may be, for example, 0° C. or higher, or a temperature higher than room temperature. The second processing temperature may be 120° C. or lower, or 80° C. or lower. When the second processing temperature is 120° C. or lower, the silicon oxide film 103 is easily etched.

[0034] The time of the HF supply step S20 may be longer than the time of the COR step. In this case, silicon tetrafluoride is easily generated on the entire surface of the substrate 100. The time of the HF supply step S20 is, for example, 20 minutes. The time of the COR step S30 is, for example, 60 seconds.

[0035] The PHT process S40 is performed after the COR process S30. The PHT process S40 includes sublimating the reaction product by performing PHT (post heat treatment) on the substrate 100 while maintaining the substrate 100 at a third treatment temperature higher than the second treatment temperature. By performing the PHT process S40, the reaction product remaining on the surface of the substrate 100 can be removed. The PHT process S40 may include supplying a third gas to the surface of the substrate 100. The third gas is, for example, hydrogen (H2) gas.

[0036] Reference Figure 3 The surface reaction in the case where the HF supply step S20 and the COR step S30 are performed continuously in this order will be described. Figure 3 This is a diagram showing the surface reaction when the HF supply step S20 is performed before the COR step S30.

[0037] like Figure 3 As shown in (a) of FIG. 1 , when hydrogen fluoride gas is supplied to the surface of the substrate 100 in the HF supply step S20 , the silicon oxide film 103 reacts with the hydrogen fluoride gas to generate silicon tetrafluoride. The chemical reaction formula at this time is as follows.

[0038] SiO2+4HF→Si F 4+2H2O (1)

[0039] Next, in the COR process S30, when fluorine gas and ammonia gas are supplied to the surface of the substrate 100, the silicon oxide film 103 reacts with the hydrogen fluoride gas and the ammonia gas to generate silicon tetrafluoride. The chemical reaction formula at this time is as follows.

[0040] SiO2+4HF+4NH3→SiF4+2H2O+4NH3 (2) In addition, in the COR process S30, the silicon tetrafluoride generated in the HF supply process S20 reacts with the fluorine gas and the ammonia gas to generate ammonium fluorosilicate [(NH4)2SiF6]. The chemical reaction formula at this time is as follows.

[0041] SiF4+2HF+2NH3→(NH4)2SiF6 (3)

[0042] When the COR process S30 is performed in a state where silicon tetrafluoride exists on the surface of the substrate 100, the reaction represented by the chemical reaction formula (3) is easier to proceed than the reaction represented by the chemical reaction formula (2). Therefore, when hydrogen fluoride gas and ammonia gas are supplied to the surface of the substrate 100, ammonium fluorosilicate is easily generated by the reaction of silicon tetrafluoride with the hydrogen fluoride gas and ammonia gas.

[0043] like Figure 3 As shown in (b), when fluorine gas and ammonia gas are supplied from the periphery of substrate 100 along the surface of substrate 100, immediately after the supply starts, silicon tetrafluoride in the outer peripheral portion of substrate 100 reacts with hydrogen fluoride gas and ammonia gas to generate ammonium fluorosilicate. This is considered to be because the reactivity of the reaction represented by chemical reaction formula (3) is high, and hydrogen fluoride gas and ammonia gas react with silicon tetrafluoride in the outer peripheral portion of substrate 100 before reaching the center portion of substrate 100 and are consumed.

[0044] Ammonium fluorosilicate suppresses the generation of silicon tetrafluoride caused by the reaction of the silicon oxide film 103 with the hydrogen fluoride gas and the ammonia gas. Therefore, the etching of the silicon oxide film 103 is suppressed by the ammonium fluorosilicate at the periphery of the substrate 100. As a result, the etching rate of the silicon oxide film 103 at the center of the substrate 100 becomes greater than the etching rate of the silicon oxide film 103 at the periphery of the substrate 100. As a result, the in-plane distribution becomes such that the etching amount of the silicon oxide film 103 at the center of the substrate 100 is greater than the etching amount of the silicon oxide film 103 at the periphery of the substrate 100. That is, the in-plane shape of the etching amount becomes convex.

[0045] When the hydrogen fluoride gas and the ammonia gas are continuously supplied to the substrate 100, Figure 3 (c) and Figure 3 As shown in (d), the region where ammonium fluorosilicate is generated expands from the periphery to the center of the substrate 100. Therefore, the etching rate of the silicon oxide film 103 at the center of the substrate 100 approaches the etching rate of the silicon oxide film 103 at the periphery of the substrate 100.

[0046] Reference Figure 4 , the surface reaction in the case where the COR step S30 is performed without performing the HF supply step S20 will be described. Figure 4 1 is a diagram showing the surface reaction in the case where the HF supply step S20 is not performed before the COR step S30.

[0047] When the COR step S30 is performed without performing the HF supply step S20, when hydrogen fluoride gas and ammonia gas are supplied to the surface of the substrate 100 in the COR step S30, the silicon oxide film 103 reacts with the hydrogen fluoride gas and ammonia gas to generate silicon tetrafluoride. The chemical reaction formula at this time is the same as the above formula (2).

[0048] like Figure 4 As shown in (a), when hydrogen fluoride gas and ammonia gas are supplied from the periphery of the substrate 100 along the surface of the substrate 100, immediately after the supply starts, the silicon oxide film 103 at the periphery is etched more than the center of the substrate 100. It is believed that this is because the reactivity of the reaction represented by the chemical reaction formula (2) is high, and the hydrogen fluoride gas and ammonia gas react with the silicon oxide film 103 at the periphery of the substrate 100 before reaching the center of the substrate 100 and are consumed. As a result, the etching amount of the silicon oxide film 103 at the periphery of the substrate 100 is greater than the etching amount of the silicon oxide film 103 at the center of the substrate 100. That is, the in-plane shape of the etching amount becomes concave.

[0049] When the hydrogen fluoride gas and the ammonia gas are continuously supplied to the substrate 100, Figure 4 As shown in (b), ammonium fluorosilicate begins to be generated at the periphery of the substrate 100. Furthermore, when hydrogen fluoride gas and ammonia gas are continuously supplied to the substrate 100, as shown in Figure 4 As shown in (c), the region where ammonium fluorosilicate is generated expands from the periphery to the center of the substrate 100. Therefore, the etching rate of the silicon oxide film 103 at the center of the substrate 100 becomes greater than the etching rate of the silicon oxide film 103 at the periphery of the substrate 100. As a result, the in-plane distribution changes from the in-plane distribution in which the etching amount of the silicon oxide film 103 at the periphery of the substrate 100 is greater than the etching amount of the silicon oxide film 103 at the center of the substrate 100 to the in-plane distribution in which the etching amount of the silicon oxide film 103 at the center of the substrate 100 is greater than the etching amount of the silicon oxide film 103 at the periphery of the substrate 100. That is, the in-plane shape of the etching amount changes from a concave shape to a convex shape.

[0050] In this way, when the COR process S30 is performed without performing the HF supply process S20, the etching time becomes long in order to adjust the in-plane shape of the etching amount to a convex shape. Therefore, it is difficult to adjust the in-plane shape of the etching amount of the silicon oxide film 103 from a concave shape to a convex shape by an etching amount less than the desired etching amount. In addition, in the case where the silicon nitride film 102 as a hard mask is formed on the surface of the substrate 100, when the etching time becomes long, the silicon nitride film 102 is easily etched, and the etching selectivity of the silicon oxide film 103 to the silicon nitride film 102 decreases.

[0051] As described above, according to the substrate processing method according to the embodiment, the HF supply step S20 is performed before the COR step S30. This makes it possible to adjust the in-plane distribution of the etching amount of the silicon oxide film 103 with a small etching amount.

[0052] 〔Substrate processing equipment〕

[0053] Reference Figure 5 The substrate processing apparatus 1 according to the embodiment will be described. Figure 5 As shown, the substrate processing apparatus 1 is a batch type apparatus that processes a plurality of substrates W simultaneously.

[0054] The substrate processing apparatus 1 includes a processing container 10 , a gas supply unit 30 , an exhaust unit 40 , a heating unit 50 , and a control unit 80 .

[0055] The processing container 10 can reduce the pressure inside. The processing container 10 accommodates the substrate W inside. The processing container 10 has an inner tube 11 and an outer tube 12. The inner tube 11 and the outer tube 12 have a cylindrical shape with a top and an open lower end. The outer tube 12 covers the outer side of the inner tube 11. The inner tube 11 and the outer tube 12 have a double-layer tube structure arranged coaxially. The inner tube 11 and the outer tube 12 are formed of a heat-resistant material such as quartz.

[0056] The top of the inner tube 11 may be flat, for example. On one side of the inner tube 11, a receiving portion 13 for receiving the gas nozzle is formed along the longitudinal direction (vertical direction) of the inner tube 11. For example, a portion of the side wall of the inner tube 11 is made to protrude outward to form a convex portion 14, and the convex portion 14 is formed as the receiving portion 13.

[0057] A rectangular opening 15 is formed along the longitudinal direction (vertical direction) of the side wall of the inner tube 11 on the side opposite to the housing portion 13 .

[0058] The opening 15 is a gas exhaust port formed to exhaust the gas in the inner tube 11. The opening 15 is formed to have a length equal to or longer than the length of the wafer boat 16 and extends in both the vertical directions.

[0059] The lower end of the processing container 10 is supported by a cylindrical manifold 17. The manifold 17 is formed of, for example, stainless steel. A flange 18 is formed at the upper end of the manifold 17. The flange 18 supports the lower end of the outer tube 12. A sealing member 19 such as an O-ring is provided between the flange 18 and the lower end of the outer tube 12. Thus, the interior of the outer tube 12 is maintained airtight.

[0060] An annular support portion 20 is provided on the inner wall of the upper portion of the manifold 17. The support portion 20 supports the lower end of the inner tube 11. A cover 21 is airtightly attached to the opening of the lower end of the manifold 17 via a sealing member 22 such as an O-ring. Thus, the opening of the lower end of the processing container 10, that is, the opening of the manifold 17 is airtightly blocked. The cover 21 is formed of, for example, stainless steel.

[0061] A rotating shaft 24 is provided through the center of the cover 21 via a magnetic fluid seal 23. The lower portion of the rotating shaft 24 is rotatably supported by an arm 25A of an elevating mechanism 25 formed of a wafer boat elevating mechanism.

[0062] A rotating plate 26 is provided at the upper end of the rotating shaft 24. A wafer boat 16 for holding a substrate W is placed on the rotating plate 26 via a quartz heat-insulating table 27. The wafer boat 16 is rotated by rotating the rotating shaft 24. The wafer boat 16 and the cover 21 are moved up and down integrally by raising and lowering the lifting mechanism 25. Thus, the wafer boat 16 is inserted into and pulled out of the processing container 10. The wafer boat 16 can be accommodated in the processing container 10. The wafer boat 16 holds a plurality of (e.g., 50 to 150) substrates W in a substantially horizontal manner with intervals in the vertical direction.

[0063] The gas supply unit 30 is configured to be able to introduce various processing gases used in the above-mentioned substrate processing method into the inner tube 11. The gas supply unit 30 includes a hydrogen fluoride supply unit 31 and an ammonia supply unit 32.

[0064] The hydrogen fluoride supply unit 31 includes a hydrogen fluoride supply pipe 31a in the processing container 10 and a hydrogen fluoride supply path 31b outside the processing container 10. In the hydrogen fluoride supply path 31b, a hydrogen fluoride supply source 31c, a mass flow controller 31d, and a valve 31e are sequentially arranged from the upstream side to the downstream side in the flow direction of the gas. Thus, the supply timing of the hydrogen fluoride gas from the hydrogen fluoride supply source 31c is controlled by the valve 31e, and the mass flow controller 31d is adjusted to a predetermined flow rate. The hydrogen fluoride gas flows from the hydrogen fluoride supply path 31b into the hydrogen fluoride supply pipe 31a, and is ejected from the hydrogen fluoride supply pipe 31a into the processing container 10.

[0065] The ammonia supply unit 32 includes an ammonia supply pipe 32a in the processing container 10 and an ammonia supply path 32b outside the processing container 10. In the ammonia supply path 32b, an ammonia source 32c, a mass flow controller 32d, and a valve 32e are sequentially arranged from the upstream side to the downstream side in the flow direction of the gas. Thus, the ammonia gas of the ammonia source 32c is controlled by the valve 32e in supply timing, and is adjusted to a predetermined flow rate by the mass flow controller 32d. Ammonia gas flows from the ammonia supply path 32b into the ammonia supply pipe 32a, and is ejected from the ammonia supply pipe 32a into the processing container 10.

[0066] Each gas supply pipe (hydrogen fluoride supply pipe 31a, ammonia supply pipe 32a) is fixed to the manifold 17. Each gas supply pipe is formed of, for example, quartz. Each gas supply pipe extends linearly in the vertical direction near the inner tube 11, and is bent into an L-shape in the manifold 17 and extends in the horizontal direction, thereby penetrating the manifold 17. The gas supply pipes are arranged in a row along the circumferential direction of the inner tube 11 and are formed at the same height.

[0067] A plurality of hydrogen fluoride ejection ports 31f are provided at a portion of the hydrogen fluoride supply pipe 31a located inside the inner pipe 11. A plurality of ammonia ejection ports 32f are provided at a portion of the ammonia supply pipe 32a located inside the inner pipe 11.

[0068] Each of the nozzles (hydrogen fluoride nozzle 31f, ammonia nozzle 32f) is formed at a predetermined interval along the extension direction of each gas supply pipe. Each nozzle discharges gas in a horizontal direction. The interval between each nozzle is set to be the same as the interval between substrates W held on the wafer boat 16, for example. The position of each nozzle in the height direction is set at the middle position between adjacent substrates W in the vertical direction. Thus, each nozzle can efficiently supply gas to the facing surfaces between adjacent substrates W.

[0069] The gas supply unit 30 may also mix a plurality of gases and eject the mixed gas from one gas supply pipe. The gas supply pipes (hydrogen fluoride supply pipe 31a, ammonia supply pipe 32a) may also have different shapes and configurations. The substrate processing apparatus 1 may also include a gas supply pipe for supplying other gases besides hydrogen fluoride gas and ammonia gas.

[0070] The exhaust unit 40 exhausts the gas exhausted from the inner tube 11 through the opening 15 and exhausted from the gas outlet 41 through the space P1 between the inner tube 11 and the outer tube 12. The gas outlet 41 is formed on the upper side wall of the manifold 17 and is located above the support unit 20. The gas outlet 41 is connected to the exhaust passage 42. The exhaust passage 42 is provided with a pressure regulating valve 43 and a vacuum pump 44 in order to exhaust the inside of the processing container 10.

[0071] The heating unit 50 is provided around the outer tube 12. The heating unit 50 is provided on, for example, the bottom plate 28. The heating unit 50 has a cylindrical shape so as to cover the outer tube 12. The heating unit 50 includes, for example, a heater, and heats each substrate W in the processing container 10.

[0072] The control unit 80 controls the operation of each unit of the substrate processing apparatus 1. The control unit 80 may be, for example, a computer. The computer program for operating each unit of the substrate processing apparatus 1 is stored in the storage medium 90. The storage medium 90 may be, for example, a floppy disk, an optical disk, a hard disk, a flash memory, a DVD, or the like.

[0073] [Operation of substrate processing apparatus]

[0074] Operations when the substrate processing method according to the embodiment is performed in the substrate processing apparatus 1 will be described.

[0075] First, the control unit 80 controls the lifting mechanism 25 to move the wafer boat 16 holding a plurality of substrates W into the processing container 10, and seals the lower opening of the processing container 10 by airtightly blocking it with the cover 21. Next, the control unit 80 controls the exhaust unit 40 to reduce the pressure in the processing container 10, and controls the heating unit 50 to adjust the temperature of the substrates W to a predetermined temperature. Each substrate W may be the substrate 100 described above.

[0076] Next, the control unit 80 controls the gas supply unit 30, the exhaust unit 40, and the heating unit 50 to perform the HF supply process S20. Specifically, first, the control unit 80 controls the gas supply unit 30 to supply the first gas into the processing container 10 while controlling the heating unit 50 to maintain the temperature of the substrate W at the first processing temperature, and controls the exhaust unit 40 to maintain the processing container 10 at the processing pressure. The first gas is a gas that contains hydrogen fluoride gas and does not contain an alkaline gas. As a result, the silicon oxide film 103 reacts with the hydrogen fluoride gas to generate silicon tetrafluoride.

[0077] Next, the control unit 80 controls the gas supply unit 30, the exhaust unit 40, and the heating unit 50 to perform the COR process S30. Specifically, first, the control unit 80 controls the gas supply unit 30 to supply the second gas into the processing container 10 while controlling the heating unit 50 to adjust and maintain the temperature of the substrate W at the second processing temperature, and controls the exhaust unit 40 to maintain the processing container 10 at the processing pressure. The second gas is a gas containing hydrogen fluoride gas and an alkaline gas. As a result, the silicon oxide film 103 reacts with the hydrogen fluoride gas and the alkaline gas to generate ammonium fluorosilicate.

[0078] Next, the control unit 80 increases the pressure in the processing container 10 to the atmospheric pressure and decreases the temperature in the processing container 10 to the unloading temperature, and then controls the lifting mechanism 25 to unload the wafer boat 16 from the processing container 10 .

[0079] [Example]

[0080] (Example 1)

[0081] In Example 1, a wafer having a silicon oxide film and a silicon nitride film on the surface is prepared. Next, the prepared wafer is placed in the processing container 10 of the substrate processing apparatus 1, and the above-mentioned HF supply process S20, COR process S30 and PHT process S40 are sequentially performed. Next, the etching amount of the silicon oxide film and the silicon nitride film is measured. The conditions of the HF supply process S20, the COR process S30 and the PHT process S40 are as follows.

[0082] (HF supply step S20)

[0083] Wafer temperature: 65°C

[0084] Processing pressure: 0.2 Torr (26.7 Pa)

[0085] First gas: HF gas / N2 gas=300sccm / 2100sccm

[0086] Processing time: 20 minutes

[0087] (COR process S30)

[0088] Wafer temperature: 65°C

[0089] Processing pressure: 0.2 Torr (26.7 Pa)

[0090] Second gas: HF gas / NH3 gas / N2 gas=300 sccm / 300 sccm / 1800 sccm

[0091] Processing time: 60 seconds

[0092] (PHT process S40)

[0093] Wafer temperature: 200°C

[0094] The third gas: H2 gas

[0095] Processing time: 30 minutes

[0096] (Comparative Example 1)

[0097] In Comparative Example 1, a wafer having a silicon oxide film and a silicon nitride film on the surface was prepared in the same manner as in Example 1. Next, the prepared wafer was placed in the processing container 10 of the above-mentioned substrate processing apparatus 1, and the COR process S30 and the PHT process S40 were sequentially performed without performing the above-mentioned HF supply process S20. Next, the etching amounts of the silicon oxide film and the silicon nitride film were measured in the same manner as in Comparative Example 1. The conditions of the COR process S30 and the PHT process S40 were the same as those of the COR process S30 and the PHT process S40 in Example 1.

[0098] Figure 6 2 is a diagram showing the results of measuring the in-plane distribution of the etching amount of the silicon oxide film. Figure 6 In FIG. 1 , the horizontal axis represents the position in the radial direction of the wafer, and the vertical axis represents the etching amount [nm] of the silicon oxide film. Figure 6 In the figure, the circular mark indicates the result of Example 1, and the triangular mark indicates the result of Comparative Example 1.

[0099] like Figure 6 As shown by the circular mark in , it can be seen that the etching amount of the silicon oxide film at the center of the wafer is greater than the etching amount of the silicon oxide film at the outer periphery of the wafer in Example 1. In other words, it can be seen that the in-plane shape of the etching amount of the silicon oxide film in Example 1 is convex.

[0100] In contrast, Figure 6 As shown by the triangle mark in , it can be seen that the etching amount of the silicon oxide film at the center of the wafer is less than the etching amount of the silicon oxide film at the outer periphery of the wafer in Comparative Example 1. In other words, it can be seen that the in-plane shape of the etching amount of the silicon oxide film is concave in Comparative Example 1. According to this result, it is shown that the in-plane shape of the etching amount of the silicon oxide film can be adjusted from a concave shape to a convex shape by performing the HF supply step S20 before the COR step S30.

[0101] Figure 7 2 is a diagram showing the results of measuring the in-plane distribution of the etching amount of the silicon nitride film. Figure 7 In FIG. 1 , the horizontal axis represents the position in the radial direction of the wafer, and the vertical axis represents the etching amount [nm] of the silicon nitride film. Figure 7 In the figure, the circular mark indicates the result of Example 1, and the triangular mark indicates the result of Comparative Example 1.

[0102] like Figure 7 As shown, it can be seen that the etching amount of the silicon nitride film in Comparative Example 1 is about 1 nm, while the etching amount of the silicon nitride film in Example 1 is about 0.2 nm. According to this result, it is shown that the etching amount of the silicon nitride film can be reduced by performing the HF supply step S20 before the COR step S30. In other words, it is shown that the etching selectivity of the silicon oxide film to the silicon nitride film can be increased.

[0103] According to the experiments conducted by the inventors so far, it is known that the more natural oxide film there is on the silicon nitride film, the more the silicon nitride film is etched by the COR process S30. Based on this, it can be considered that the natural oxide film on the silicon nitride film is etched by the HF supply process S20, and thus there is almost no natural oxide film on the silicon nitride film at the time point of the COR process S30, thereby suppressing the etching of the silicon nitride film.

[0104] The embodiments disclosed herein are to be considered in all respects as illustrative and non-restrictive. The above embodiments may be omitted, replaced, or modified in various ways without departing from the appended claims and the gist thereof.

[0105] In the above-mentioned embodiment, the substrate processing apparatus is described as a batch type apparatus that processes a plurality of substrates simultaneously, but the present disclosure is not limited thereto. For example, the substrate processing apparatus may also be a single type apparatus that processes substrates one by one. For example, the substrate processing apparatus may also be a semi-batch type apparatus that rotates a plurality of substrates mounted on a rotating table through a rotating table in a processing container, so that the substrates are processed sequentially through a plurality of processing areas arranged along the rotation direction of the rotating table.

[0106] Description of Reference Numerals

[0107] S10: preparation process; S20: HF supply process; S30: COR process.

Claims

1. A substrate processing method, comprising the following steps: Step (a), preparing a substrate having a silicon oxide film on its surface; Step (b), supplying a first gas including hydrogen fluoride gas and not including alkaline gas to the surface of the substrate; and A step (c) of supplying a second gas including a hydrogen fluoride gas and an alkaline gas to the surface of the substrate after the step (b).

2. The substrate processing method according to claim 1, wherein: The step (c) is continuously performed after the step (b) while the supply of the hydrogen fluoride gas is continued.

3. The substrate processing method according to claim 1, wherein: The time of the step (b) is longer than that of the step (c).

4. The substrate processing method according to claim 1, wherein: The step (b) includes reacting the silicon oxide film with the hydrogen fluoride gas to generate silicon tetrafluoride, The step (c) includes reacting the silicon tetrafluoride, the hydrogen fluoride gas, and the alkaline gas to generate ammonium fluorosilicate.

5. The substrate processing method according to claim 1, wherein: In the step (b) and the step (c), the substrate is maintained at the same temperature.

6. The substrate processing method according to claim 1, wherein: In the step (c), the second gas is supplied along the surface of the substrate.

7. The substrate processing method according to claim 1, wherein: The step (c) includes etching the silicon oxide film so that an etching amount of the silicon oxide film at a central portion of the substrate is greater than an etching amount of the silicon oxide film at an outer peripheral portion of the substrate.

8. The substrate processing method according to claim 1, wherein: The alkaline gas is ammonia.

9. The substrate processing method according to any one of claims 1 to 8, wherein: The method further includes a step (d) of, after the step (c), heat-treating the substrate at a temperature higher than the temperature in the step of supplying the second gas.

10. A substrate processing device comprising: a processing container that receives a substrate; a gas supply unit for supplying a processing gas into the processing container; and Control Department, in, The control unit is configured to execute a process including the following steps: placing a substrate having a silicon oxide film on its surface into the processing container; supplying a first gas including hydrogen fluoride gas and not including alkaline gas to the surface of the substrate accommodated in the processing container; and After the step of supplying the first gas, a second gas including a hydrogen fluoride gas and an alkaline gas is supplied to the surface of the substrate accommodated in the processing container.

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