Substrate processing method and substrate processing apparatus

Abstract

To provide technique enabling etching amount of an object film to be controlled.SOLUTION: A substrate processing method according to an embodiment of a present disclosure, includes: a step of preparing a substrate having an object film including silicon, carbon and nitrogen on a front surface; a step of supplying hydrogen gas and oxygen gas to the object film, and oxidizing a front layer of the object film thereby forming an oxidized film; and a step of etching the oxidized film.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus.

Background Art

[0002] A technique for etching a silicon nitride film by a chemical oxide removal treatment is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a technique capable of controlling the etching amount of a target film.

Means for Solving the Problems

[0005] A substrate processing method according to an aspect of the present disclosure includes: preparing a substrate having a target film containing silicon, carbon, and nitrogen on a surface; supplying hydrogen gas and oxygen gas to the target film to oxidize a surface layer of the target film to form an oxide film; and etching the oxide film. death 、 The etching step includes supplying a gas containing a fluorine-containing gas and a basic gas to the target film and, without generating plasma, transforming at least a portion of the target film into a reaction product; and heating the substrate to sublimate the reaction product. 。

Effects of the Invention

[0006] According to the present disclosure, the etching amount of the target film can be controlled.

Brief Description of the Drawings

[0007] [Figure 1] FIG. 1 is a flowchart showing a substrate processing method according to an embodiment. [Figure 2]Figure 2 is a cross-sectional view showing a substrate processing method according to an embodiment. [Figure 3] Figure 3 is a time chart showing the substrate processing method according to the embodiment. [Figure 4] Figure 4 is a schematic diagram showing a substrate processing apparatus according to an embodiment. [Figure 5] Figure 5 shows the results of the etching amount evaluation. [Modes for carrying out the invention]

[0008] Hereinafter, exemplary embodiments of the present disclosure, not limited to those described herein, will be described with reference to the attached drawings. In all attached drawings, identical or corresponding members or components are denoted by the same or corresponding reference numerals, and redundant descriptions are omitted.

[0009] [Substrate processing method] Referring to Figures 1 to 3, the substrate processing method according to the embodiment will be described. As shown in Figure 1, the substrate processing method according to the embodiment includes a preparation step S10, an oxidation step S20, and an etching step S30.

[0010] In preparation step S10, a substrate 101 having the target film 102 on its surface is prepared, as shown in Figure 2(a). The substrate 101 may be, for example, a silicon wafer. The target film 102 may be, for example, a film containing silicon (Si), carbon (C), and nitrogen (N). The target film 102 may be, for example, a SiCN film. The target film 102 may further contain elements other than silicon, carbon, and nitrogen. These different elements may be, for example, oxygen (O), boron (B), or a combination thereof.

[0011] The oxidation step S20 is performed after the preparation step S10. In the oxidation step S20, as shown in Figure 2(b), the surface layer of the target film 102 is oxidized to form an oxide film 103. The oxidation step S20 includes, for example, as shown in Figure 3, supplying hydrogen gas and oxygen gas to the target film 102 while maintaining the temperature of the substrate 101 at a first temperature T1, and oxidizing the surface layer of the target film 102 to form an oxide film 103. The first temperature T1 may be, for example, 700°C or higher and 800°C or lower. The oxidation step S20 may also include supplying an inert gas simultaneously with the hydrogen gas and oxygen gas.

[0012] The etching process S30 is performed after the oxidation process S20. In the etching process S30, the oxide film 103 is selectively etched, as shown in Figure 2(c). The etching process S30 includes, for example, a cooling process S31, a COR process S32, a heating process S33, and a PHT process S34, as shown in Figure 3.

[0013] The cooling step S31 includes lowering the temperature of the substrate 101 from a first temperature T1 to a second temperature T2, as shown in Figure 3. The second temperature T2 may be, for example, lower than the first temperature T1. The second temperature T2 may be, for example, 50°C or higher and 100°C or lower.

[0014] The COR step S32 is performed after the temperature of the substrate 101 has stabilized at a second temperature T2 in the cooling step S31. The COR step S32 includes chemical oxide removal (COR), which is a chemical etching process performed without generating plasma, thereby transforming at least a portion of the target film 102, including the surface layer, into a reaction product. The COR step S32 may include, for example, maintaining the temperature of the substrate 101 at the second temperature T2. The COR step S32 includes supplying a fluorine-containing gas and a basic gas to the target film 102, as shown in Figure 3, for example, and reacting the fluorine-containing gas and the basic gas with the oxide film 103 to produce ammonium silicoid fluoride [(NH4)2SiF6]. The fluorine-containing gas may be, for example, hydrogen fluoride (HF) gas. The basic gas may be, for example, ammonia (NH3) gas. The COR step S32 may also include supplying an inert gas simultaneously with the fluorine-containing gas and the basic gas.

[0015] The heating step S33 is performed after the COR step S32. The heating step S33 includes raising the temperature of the substrate 101 from a second temperature T2 to a third temperature T3. The third temperature T3 may be, for example, lower than the first temperature T1 and higher than the second temperature T2. The third temperature T3 may also be higher than the first temperature T1. The third temperature T3 may be, for example, 300°C or higher.

[0016] The PHT step S34 is performed after the heating step S33. The PHT step S34 includes sublimating the reaction product, such as ammonium silicofluoride, by PHT (post heat treatment), which is performed by heating while maintaining the temperature of the substrate 101 at a third temperature T3, as shown in Figure 3, for example.

[0017] When the etching step S30 includes the COR step S32 and the PHT step S34, the target film 102 can be left remaining and the oxide film 103 can be selectively etched and removed. Therefore, by adjusting the thickness of the oxide film 103 formed on the surface layer of the target film 102 in the oxidation step S20, the etching amount of the target film 102 can be controlled. The thickness of the oxide film 103 can be adjusted, for example, by controlling the time for supplying hydrogen gas and oxygen gas to the target film 102 in the oxidation step S20. The thickness of the oxide film 103 can be adjusted, for example, by controlling the first temperature T1 in the oxidation step S20.

[0018] The etching step S30 may be performed, for example, in the same processing container as the oxidation step S20. In this case, the target film can be etched in one processing container. The etching step S30 may be performed, for example, in a processing container different from the oxidation step S20. In this case, the temperature reduction step S31 and the temperature increase step S33 can be omitted.

[0019] The etching step S30 may be performed, for example, in a processing container that accommodates a plurality of substrates 101 in a shelf shape. In this case, the target film 102 can be etched for a plurality of substrates 101 at once. Therefore, the productivity is improved.

[0020] 〔Substrate Processing Apparatus〕 Referring to FIG. 4, the substrate processing apparatus involved in the embodiment will be described. As shown in FIG. 4, the substrate processing apparatus 1 is a batch-type apparatus that processes a plurality of substrates W at once.

[0021] 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.

[0022] The processing container 10 can be depressurized inside and accommodates the substrate W. The processing container 10 has a ceilinged cylindrical inner tube 11 with an open lower end and a ceilinged cylindrical outer tube 12 with an open lower end that covers the outside of the inner tube 11. The inner tube 11 and the outer tube 12 are formed of a heat-resistant material such as quartz. The inner tube 11 and the outer tube 12 have a double-tube structure arranged coaxially.

[0023] The ceiling of the inner tube 11 may be, for example, flat. A housing portion 13 for accommodating a gas nozzle is formed on one side of the inner tube 11 along its longitudinal direction (vertical direction). For example, a part of the side wall of the inner tube 11 is made to protrude outward to form a convex portion 14, and the inside of the convex portion 14 is formed as the housing portion 13.

[0024] On the side wall opposite the inner tube 11, facing the housing section 13, a rectangular opening 15 is formed along its longitudinal direction (vertical direction).

[0025] The opening 15 is a gas exhaust port formed to allow the gas inside the inner pipe 11 to be exhausted. The length of the opening 15 is the same as the length of the boat 16, or it is longer than the length of the boat 16 and extends vertically in both directions.

[0026] The lower end of the processing container 10 is supported by a cylindrical manifold 17. The manifold 17 is made 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 pipe 12. A sealing member 19, such as an O-ring, is provided between the flange 18 and the lower end of the outer pipe 12. This maintains an airtight seal inside the outer pipe 12.

[0027] An annular support portion 20 is provided on the inner wall of the upper part of the manifold 17. The support portion 20 supports the lower end of the inner pipe 11. A lid 21 is airtightly attached to the opening at the lower end of the manifold 17 via a sealing member 22 such as an O-ring. This airtightly closes the opening at the lower end of the processing container 10, i.e., the opening of the manifold 17. The lid 21 is made of, for example, stainless steel.

[0028] A rotating shaft 24 is provided through the center of the lid 21 via a magnetic fluid seal 23. The lower part of the rotating shaft 24 is rotatably supported by an arm 25A of a lifting mechanism 25, which consists of a boat elevator.

[0029] A rotating plate 26 is provided at the upper end of the rotating shaft 24. A boat 16 for holding substrates W is placed on the rotating plate 26 via a quartz warming stand 27. The boat 16 rotates by rotating the rotating shaft 24. The boat 16 moves up and down together with the lid 21 by raising and lowering the lifting mechanism 25. This allows the boat 16 to be inserted into and removed from the processing container 10. The boat 16 can be housed inside the processing container 10. The boat 16 holds multiple (e.g., 50 to 150) substrates W in a substantially horizontal position with vertical spacing between them.

[0030] The gas supply unit 30 is configured to allow the introduction of various processing gases used in the substrate processing method described above into the inner tube 11. The gas supply unit 30 includes a hydrogen supply unit 31, an oxygen supply unit 32, a hydrogen fluoride supply unit 33, and an ammonia supply unit 34.

[0031] The hydrogen supply unit 31 includes a hydrogen supply pipe 31a inside the processing container 10 and a hydrogen supply path 31b outside the processing container 10. In the hydrogen supply path 31b, a hydrogen source 31c, a mass flow controller 31d, and a valve 31e are provided in order from the upstream side to the downstream side in the direction of gas flow. As a result, the hydrogen gas from the hydrogen source 31c is supplied at a timing controlled by the valve 31e and adjusted to a predetermined flow rate by the mass flow controller 31d. The hydrogen gas flows from the hydrogen supply path 31b into the hydrogen supply pipe 31a and is discharged from the hydrogen supply pipe 31a into the processing container 10.

[0032] The oxygen supply unit 32 includes an oxygen supply pipe 32a inside the processing container 10 and an oxygen supply path 32b outside the processing container 10. In the oxygen supply path 32b, an oxygen source 32c, a mass flow controller 32d, and a valve 32e are provided in order from the upstream side to the downstream side in the direction of gas flow. As a result, the supply timing of the oxygen gas from the oxygen source 32c is controlled by the valve 32e, and the flow rate is adjusted to a predetermined level by the mass flow controller 32d. The oxygen gas flows from the oxygen supply path 32b into the oxygen supply pipe 32a and is discharged from the oxygen supply pipe 32a into the processing container 10.

[0033] The hydrogen fluoride supply unit 33 includes a hydrogen fluoride supply pipe 33a inside the processing container 10 and a hydrogen fluoride supply path 33b outside the processing container 10. The hydrogen fluoride supply path 33b is equipped with a hydrogen fluoride source 33c, a mass flow controller 33d, and a valve 33e, arranged in order from upstream to downstream in the gas flow direction. As a result, the hydrogen fluoride gas from the hydrogen fluoride source 33c is supplied at a timing controlled by the valve 33e and adjusted to a predetermined flow rate by the mass flow controller 33d. The hydrogen fluoride gas flows from the hydrogen fluoride supply path 33b into the hydrogen fluoride supply pipe 33a and is discharged from the hydrogen fluoride supply pipe 33a into the processing container 10. Hydrogen fluoride gas is an example of a fluorine-containing gas.

[0034] The ammonia supply unit 34 includes an ammonia supply pipe 34a inside the processing container 10 and an ammonia supply path 34b outside the processing container 10. In the ammonia supply path 34b, an ammonia source 34c, a mass flow controller 34d, and a valve 34e are provided in order from the upstream side to the downstream side in the direction of gas flow. As a result, the supply timing of the ammonia gas from the ammonia source 34c is controlled by the valve 34e, and the flow rate is adjusted to a predetermined level by the mass flow controller 34d. The ammonia gas flows from the ammonia supply path 34b into the ammonia supply pipe 34a and is discharged from the ammonia supply pipe 34a into the processing container 10. Ammonia gas is an example of a basic gas.

[0035] Each gas supply pipe (hydrogen supply pipe 31a, oxygen supply pipe 32a, hydrogen fluoride supply pipe 33a, ammonia supply pipe 34a) is fixed to the manifold 17. Each gas supply pipe is made of, for example, quartz. Each gas supply pipe extends linearly in the vertical direction near the inner pipe 11 and then extends horizontally in an L-shape within the manifold 17, thereby penetrating the manifold 17. The gas supply pipes are arranged side by side along the circumferential direction of the inner pipe 11 and are formed at the same height.

[0036] Multiple hydrogen outlets 31f are provided in the hydrogen supply pipe 31a at the location inside the inner pipe 11. Multiple oxygen outlets 32f are provided in the oxygen supply pipe 32a at the location inside the inner pipe 11. Multiple hydrogen fluoride outlets 33f are provided in the hydrogen fluoride supply pipe 33a at the location inside the inner pipe 11. Multiple ammonia outlets 34f are provided in the ammonia supply pipe 34a at the location inside the inner pipe 11.

[0037] Each outlet (hydrogen outlet 31f, oxygen outlet 32f, hydrogen fluoride outlet 33f, ammonia outlet 34f) is formed at predetermined intervals along the extending direction of each gas supply pipe. Each outlet releases gas horizontally. The spacing between each outlet is set to be the same as, for example, the spacing between substrates W held in the boat 16. The height position of each outlet is set to be an intermediate position between adjacent substrates W in the vertical direction. This allows each outlet to efficiently supply gas to the opposing surfaces between adjacent substrates W.

[0038] The gas supply unit 30 may mix multiple types of gases and discharge the mixed gas from a single supply pipe. Each gas supply pipe (hydrogen supply pipe 31a, oxygen supply pipe 32a, hydrogen fluoride supply pipe 33a, ammonia supply pipe 34a) may have a different shape or arrangement from one another. In addition, the substrate processing apparatus 1 may further include supply pipes for supplying other gases in addition to hydrogen gas, oxygen gas, hydrogen fluoride, and ammonia gas.

[0039] The exhaust section 40 exhausts the gas discharged from the inner pipe 11 through the opening 15 and through the space P1 between the inner pipe 11 and the outer pipe 12, which is discharged from the gas outlet 41. The gas outlet 41 is located on the upper side wall of the manifold 17 and is formed above the support section 20. An exhaust passage 42 is connected to the gas outlet 41. A pressure regulating valve 43 and a vacuum pump 44 are sequentially installed in the exhaust passage 42 to allow exhaust from inside the processing container 10.

[0040] The heating section 50 is provided around the outer tube 12. The heating section 50 is provided, for example, on the base plate 28. The heating section 50 has a cylindrical shape so as to cover the outer tube 12. The heating section 50 includes, for example, a heating element and heats the substrate W inside the processing container 10.

[0041] The control unit 80 controls the operation of each part of the substrate processing apparatus 1. The control unit 80 may be, for example, a computer. The computer program that controls the operation of each part of the substrate processing apparatus 1 is stored in the storage medium 90. The storage medium 90 may be, for example, a flexible disk, compact disk, hard disk, flash memory, DVD, etc.

[0042] [Operation of the circuit board processing unit] The operation when the substrate processing method according to the embodiment is implemented in the substrate processing apparatus 1 will be described below.

[0043] First, the control unit 80 controls the lifting mechanism 25 to load the boat 16 holding multiple substrates W into the processing container 10, and then seals the opening at the lower end of the processing container 10 airtight with the lid 21. Each substrate W is a substrate 101 having a target film 102 on its surface.

[0044] Next, the control unit 80 controls the gas supply unit 30, the exhaust unit 40, and the heating unit 50 to execute the oxidation process S20. Specifically, first, the control unit 80 controls the exhaust unit 40 to reduce the pressure inside the processing container 10 to a predetermined level, and controls the heating unit 50 to adjust and maintain the temperature of the substrate W at a first temperature T1. Then, the control unit 80 controls the gas supply unit 30 to supply hydrogen gas and oxygen gas into the processing container 10. As a result, the surface layer of the target film 102 is oxidized and an oxide film 103 is formed.

[0045] Next, the control unit 80 controls the gas supply unit 30, the exhaust unit 40, and the heating unit 50 to execute the etching process S30. Specifically, first, the control unit 80 controls the exhaust unit 40 to reduce the pressure inside the processing container 10 to a predetermined level, and controls the heating unit 50 to adjust and maintain the temperature of the substrate W at a second temperature T2. Next, the control unit 80 controls the gas supply unit 30 to supply hydrogen fluoride gas and ammonia gas into the processing container 10. As a result, the hydrogen fluoride gas and ammonia gas react with the oxide film 103 to produce ammonium silicofluoride [(NH4)2SiF6]. Next, the control unit 80 controls the heating unit 50 to heat the temperature of the substrate W to a third temperature T3, and sublimate the ammonium silicofluoride. This allows the oxide film 103 to be selectively etched and removed while leaving the target film 102 intact. Therefore, the amount of etching of the target film 102 can be controlled by adjusting the thickness of the oxide film 103 formed on the surface of the target film 102 in the oxidation process S20.

[0046] Next, the control unit 80 increases the pressure inside the processing container 10 to atmospheric pressure, then lowers the temperature inside the processing container 10 to the discharge temperature, and then controls the lifting mechanism 25 to discharge the boat 16 from inside the processing container 10.

[0047] [Examples] An example in which it was confirmed that the amount of etching of the target film 102 can be controlled by the substrate processing method according to the embodiment will be described.

[0048] In this example, a substrate having a SiCN film on its surface was prepared, and the prepared substrate was placed in the processing container 10 of the substrate processing apparatus 1 described above. The SiCN film was etched according to conditions 1 to 6 shown below. The amount of etching of the SiCN film was calculated by measuring the film thickness before and after etching with a spectroscopic ellipsometer and determining the difference between the two. The SiCN film is an example of the target film 102.

[0049] (Condition 1) Under condition 1, the etching process S30 was performed on the prepared substrate without performing the oxidation process S20. In the etching process S30, the cooling process S31, the COR process S32, the heating process S33, and the PHT process S34 were performed in this order. In the COR process S32, the substrate was heated for 5 minutes while maintaining its temperature at 75°C.

[0050] (Condition 2) In Condition 2, the time for the COR process S32 was changed to 10 minutes compared to Condition 1. All other conditions were the same as in Condition 1.

[0051] (Condition 3) In condition 3, the oxidation process S20 and etching process S30 were performed on the prepared substrate in this order. In the oxidation process S20, the time for supplying hydrogen gas and oxygen gas into the processing container 10 was set to 10 minutes. The conditions for the etching process S30 were the same as those for the etching process S30 in condition 1.

[0052] (Condition 4) In Condition 4, the time for the COR process S32 was changed to 10 minutes compared to Condition 3. All other conditions were the same as in Condition 3.

[0053] (Condition 5) In condition 5, the time of oxidation step S20 was changed to 30 minutes compared to condition 3. All other conditions were the same as in condition 3.

[0054] (Condition 6) In Condition 6, the time for the COR process S32 was changed to 10 minutes compared to Condition 5. All other conditions were the same as in Condition 5.

[0055] For comparison, a substrate having a SiN film on its surface was prepared, and the prepared substrate was placed in the processing container 10 of the substrate processing apparatus 1 described above, and the SiN film was etched according to the conditions 7 and 8 shown below. The amount of etching of the SiN film was calculated by measuring the film thickness before and after etching with a spectroscopic ellipsometer and determining the difference between the two.

[0056] (Condition 7) Condition 7 is the same as Condition 1.

[0057] (Condition 8) Condition 8 is the same as condition 2.

[0058] For comparison, a substrate having an SiO2 film on its surface was prepared, and the prepared substrate was placed in the processing container 10 of the substrate processing apparatus 1 described above, and the SiO2 film was etched according to the conditions 9 and 10 shown below. The amount of etching of the SiO2 film was calculated by measuring the film thickness before and after etching with a spectroscopic ellipsometer and determining the difference between the two.

[0059] (Condition 9) Condition 9 is the same as Condition 1.

[0060] (Condition 10) Condition 10 is the same as condition 2.

[0061] Figure 5 shows the results of evaluating the etching amount. Figure 5 shows the etching amount [nm] of the SiCN film etched under conditions 1 to 6, the etching amount [nm] of the SiN film etched under conditions 7 and 8, and the etching amount [nm] of the SiO2 film etched under conditions 9 and 10.

[0062] As shown in Figure 5, the etching amount is approximately 0 nm under conditions 1 and 2, while the etching amount is in the range of 20 nm to 60 nm under conditions 3 to 6. This result indicates that the SiCN film is hardly etched when the oxidation process S20 is not performed, but becomes etchable when the oxidation process S20 is performed.

[0063] As shown in Figure 5, the etching amount is in the range of 20 nm to 30 nm under conditions 3 and 4, and under conditions 5 and 6, the etching amount is in the range of 50 nm to 60 nm. From these results, it was shown that the etching amount of the SiCN film depends on the time of the oxidation process S20 and not on the time of the COR process S32. In other words, it was shown that the etching amount of the SiCN film can be controlled by changing the time of the oxidation process S20. Specifically, the etching amount of the SiCN film can be increased by increasing the time of the oxidation process S20.

[0064] As shown in Figure 5, the etching amount is in the range of 15 nm to 30 nm under conditions 7 to 10. This result indicates that, unlike SiCN films, SiN films and SiO2 films can be etched by performing the etching process S30 without performing the oxidation process S20.

[0065] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The above embodiments may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims.

[0066] In the embodiments described above, the substrate processing apparatus is described as a batch-type apparatus that processes multiple substrates at once, but the disclosure is not limited thereto. For example, the substrate processing apparatus may be a single-wafer apparatus that processes substrates one at a time. [Explanation of symbols]

[0067] S10 Preparation process S20 Oxidation process S30 Etching process

Claims

1. A step of preparing a substrate having a target film containing silicon, carbon, and nitrogen on its surface, A step of supplying hydrogen gas and oxygen gas to the target film and oxidizing the surface layer of the target film to form an oxide film, The process of etching the aforementioned oxide film, It has, The etching process described above is: A step of supplying a gas containing a fluorine-containing gas and a basic gas to the target film and converting at least a portion of the target film into a reaction product without generating plasma, A step of heating the substrate to sublimate the reaction product, including, Substrate processing method.

2. The fluorine-containing gas is hydrogen fluoride gas. The basic gas is ammonia gas. The substrate processing method according to claim 1.

3. The etching step is performed in the same processing vessel as the oxide film formation step. The substrate processing method according to claim 1.

4. The processing container accommodates a plurality of substrates in a shelf-like manner. The substrate processing method according to claim 3.

5. The aforementioned target film further comprises elements other than silicon, carbon, and nitrogen. The substrate processing method according to claim 1.

6. The aforementioned elements are oxygen, boron, or a combination thereof. The substrate processing method according to claim 5.

7. The aforementioned target film is a SiCN film. The substrate processing method according to claim 1.

8. Processing container and A gas supply unit that supplies gas to the processing container, Control unit and Equipped with, The control unit, A step of preparing a substrate having a target film containing silicon, carbon, and nitrogen on its surface, A step of supplying hydrogen gas and oxygen gas to the target film and oxidizing the surface layer of the target film to form an oxide film, The process of etching the aforementioned oxide film, It is configured to perform, The etching process described above is: A step of supplying a gas containing a fluorine-containing gas and a basic gas to the target film and converting at least a portion of the target film into a reaction product without generating plasma, A step of heating the substrate to sublimate the reaction product, including, Circuit board processing equipment.

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