Substrate processing method and substrate processing device

Abstract

To provide a technique capable of selectively removing part of a silicon film.SOLUTION: A substrate processing method includes the steps of: preparing a substrate including a non-doped silicon film and a phosphorus-doped silicon film, at least the phosphorus-doped silicon film being exposed on a surface thereof; and supplying a halogen gas to the substrate to selectively etch and remove the phosphorus-doped silicon film out of the non-doped silicon film and the phosphorus-doped silicon film.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] A technique for etching a silicon film using chlorine gas is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-228580 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides techniques that can selectively remove portions of a silicon film. [Means for solving the problem]

[0005] A substrate processing method according to an aspect of the present disclosure includes the steps of: preparing a substrate including a non-doped silicon film and a phosphorus-doped silicon film, with at least the phosphorus-doped silicon film exposed on a surface; and supplying a halogen gas to the substrate to selectively etch and remove the phosphorus-doped silicon film from the non-doped silicon film and the phosphorus-doped silicon film. Effect of the Invention

[0006] According to the present disclosure, portions of the silicon film can be selectively removed. [Brief description of the drawings]

[0007] [Figure 1] 3 is a flowchart illustrating a substrate processing method according to the embodiment. [Diagram 2]1A to 1C are cross-sectional views illustrating a substrate processing method according to an embodiment of the present invention. [Diagram 3] 1 is a cross-sectional view showing a substrate processing apparatus according to an embodiment. [Figure 4] FIG. 13 is a diagram showing the measurement results of the etching rate of an amorphous silicon film. [Diagram 5] FIG. 13 is a diagram showing the measurement results of the etching rate of a polysilicon film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0009] [Substrate Processing Method] A substrate processing method according to an embodiment will be described with reference to Figures 1 and 2. As shown in Figure 1, the substrate processing method according to the embodiment includes steps S1 and S2.

[0010] 2(a), a substrate 100 is prepared, which includes a non-doped silicon film 102 and a phosphorus-doped silicon film 103, with at least the phosphorus-doped silicon film 103 exposed on the surface. The non-doped silicon film 102 and the phosphorus-doped silicon film 103 are stacked in this order on a base 101, for example.

[0011] The substrate 100 is, for example, a silicon wafer. There is no particular limitation on the type of the substrate 100. The substrate 100 may be another semiconductor wafer.

[0012] The base 101 is, for example, a silicon oxide film. There is no particular limitation on the type of the base 101. The base 101 may be another film such as a silicon nitride film.

[0013] The non-doped silicon film 102 is provided on a base 101. The non-doped silicon film 102 is, for example, a non-doped polysilicon film. The non-doped polysilicon film can be formed by heat treating and crystallizing a non-doped amorphous silicon film. The non-doped amorphous silicon film is formed by, for example, crystallizing a silicon-containing gas, such as monosilane (SiH 4 The non-doped silicon film 102 may be an non-doped amorphous silicon film.

[0014] The phosphorus-doped silicon film 103 is provided on the non-doped silicon film 102. The phosphorus-doped silicon film 103 is, for example, a phosphorus-doped polysilicon film. The phosphorus-doped polysilicon film can be formed by heat-treating and crystallizing the phosphorus-doped amorphous silicon film. The phosphorus-doped amorphous silicon film can be formed by, for example, crystallizing a monosilane gas, which is a silicon-containing gas, and a phosphine (PH 3 The phosphorus-doped silicon film 103 may be a phosphorus-doped amorphous silicon film.

[0015] Step S2 is performed after step S1. In step S2, as shown in FIG. 2(b), a halogen gas, chlorine (Cl 2) gas is supplied to selectively etch and remove the phosphorus-doped silicon film 103 out of the non-doped silicon film 102 and the phosphorus-doped silicon film 103. At this time, it is preferable to adjust the temperature of the substrate 100 to a temperature (hereinafter referred to as "etching temperature") at which the etching selectivity of the phosphorus-doped silicon film 103 to the non-doped silicon film 102 becomes high. In this case, etching of the non-doped silicon film 102 can be suppressed. The etching temperature can be determined, for example, by a preliminary experiment. For example, when the non-doped silicon film 102 is a non-doped polysilicon film and the phosphorus-doped silicon film 103 is a phosphorus-doped polysilicon film, the etching temperature is preferably 200°C or more and 400°C or less. When the etching temperature is 200°C or more, the phosphorus-doped polysilicon film is easily etched. When the etching temperature is 400°C or less, etching of the non-doped polysilicon film is easily suppressed.

[0016] According to the substrate processing method of the embodiment described above, first, a substrate 100 including a non-doped silicon film 102 and a phosphorus-doped silicon film 103, at least the phosphorus-doped silicon film 103 being exposed on the surface, is prepared. Next, chlorine gas is supplied to the substrate 100, and the phosphorus-doped silicon film 103 of the non-doped silicon film 102 and the phosphorus-doped silicon film 103 is selectively etched and removed. The chlorine gas etches and removes the phosphorus-doped silicon film 103 without etching the non-doped silicon film 102. Therefore, when etching the phosphorus-doped silicon film 103, the non-doped silicon film 102 under the phosphorus-doped silicon film 103 can be left. That is, the phosphorus-doped silicon film 103 of the non-doped silicon film 102 and the phosphorus-doped silicon film 103 can be selectively etched and removed.

[0017] In the above embodiment, the case where the substrate 100 in which only the phosphorus-doped silicon film 103 is exposed on the surface is prepared in step S1 has been described, but the present invention is not limited to this. For example, the substrate 100 in which the non-doped silicon film 102 and the phosphorus-doped silicon film 103 are exposed on the surface may be prepared in step S1.

[0018] In the above embodiment, the case where the phosphorus-doped silicon film 103 is formed on the non-doped silicon film 102 in step S1 has been described, but the present invention is not limited to this. For example, the phosphorus-doped silicon film 103 may be formed by modifying the surface layer of the non-doped silicon film 102 by supplying phosphine gas without supplying monosilane gas to the substrate 100 having the non-doped silicon film 102 formed on the underlayer 101.

[0019] In the above embodiment, the case where step S2 is performed after step S1 has been described, but the present invention is not limited to this. For example, between steps S1 and S2, a step of immersing the substrate 100 in dilute hydrofluoric acid (DHF) to remove a native oxide film that may be present on the surface of the phosphorus-doped silicon film 103 may be performed.

[0020] [Substrate Processing Apparatus] The substrate processing apparatus 1 according to the embodiment will be described with reference to Fig. 3. As shown in Fig. 3, 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 vessel 10 is capable of reducing the pressure inside. The processing vessel 10 accommodates a substrate W therein. The processing vessel 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 ceiling and an open lower end. The outer tube 12 covers the outside of the inner tube 11. The inner tube 11 and the outer tube 12 have a double tube structure arranged coaxially. The inner tube 11 and the outer tube 12 are formed of a heat-resistant material such as quartz.

[0023] The ceiling of the inner pipe 11 may be flat, for example. A storage section 13 for storing a gas nozzle is formed along the longitudinal direction (vertical direction) of the inner pipe 11 on one side. For example, a part of the side wall of the inner pipe 11 protrudes outward to form a convex section 14, and the inside of the convex section 14 is formed as the storage section 13.

[0024] In the side wall on the opposite side of the inner tube 11 facing the storage portion 13, a rectangular opening 15 is formed along the longitudinal direction (vertical direction).

[0025] The opening 15 is a gas exhaust port formed so as to be able to exhaust the gas inside the inner tube 11. The length of the opening 15 is the same as the length of the boat 16, or is formed so as to extend longer than the length of the boat 16 in the vertical direction.

[0026] The lower end of the processing vessel 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 tube 12. A seal member 19 such as an O-ring is provided between the flange 18 and the lower end of the outer tube 12. This keeps the inside of the outer tube 12 airtight.

[0027] An annular support 20 is provided on the inner wall of the upper part of the manifold 17. The support 20 supports the lower end of the inner tube 11. A lid 21 is air-tightly attached to the opening at the lower end of the manifold 17 via a seal member 22 such as an O-ring. This air-tightly closes the opening at the lower end of the processing vessel 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 penetrating the center of the lid 21 via a magnetic fluid seal 23. A lower portion of the rotating shaft 24 is rotatably supported by an arm 25A of an elevation mechanism 25 made up of a boat elevator.

[0029] A rotating plate 26 is provided at the upper end of the rotating shaft 24. The boat 16, which holds the substrates W, is placed on the rotating plate 26 via a quartz heat retention 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 vessel 10. The boat 16 can be accommodated within the processing vessel 10. The boat 16 holds a plurality of substrates W (e.g., 50 to 150 substrates) approximately horizontally with a gap between them in the vertical direction.

[0030] The gas supply unit 30 is configured to be able to introduce various process gases used in the above-mentioned substrate processing method into the inner tube 11. The gas supply unit 30 includes a phosphine supply unit 31 and a monosilane supply unit 32.

[0031] The phosphine supply unit 31 includes a supply pipe 31a inside the processing vessel 10 and a supply path 31b outside the processing vessel 10. A phosphine source 31c, a mass flow controller 31d, and a valve 31e are provided on the supply path 31b, in this order from the upstream side to the downstream side in the gas flow direction. Thus, the supply timing of the phosphine gas from the phosphine source 31c is controlled by the valve 31e, and the flow rate is adjusted to a predetermined value by the mass flow controller 31d. The phosphine gas flows from the supply path 31b into the supply pipe 31a and is discharged from the supply pipe 31a into the processing vessel 10.

[0032] The monosilane supply unit 32 includes a supply pipe 32a inside the processing vessel 10 and a supply path 32b outside the processing vessel 10. A monosilane source 32c, a mass flow controller 32d, and a valve 32e are provided on the supply path 32b, in this order from the upstream side to the downstream side in the gas flow direction. Thus, the supply timing of the monosilane gas from the monosilane source 32c is controlled by the valve 32e, and the flow rate is adjusted to a predetermined value by the mass flow controller 32d. The monosilane gas flows from the supply path 32b into the supply pipe 32a and is discharged from the supply pipe 32a into the processing vessel 10.

[0033] The supply pipes 31a, 32a are fixed to the manifold 17. The supply pipes 31a, 32a are made of, for example, quartz. The supply pipes 31a, 32a extend linearly in the vertical direction near the inner pipe 11, and are bent in an L-shape within the manifold 17 to extend horizontally, thereby penetrating the manifold 17. The supply pipes 31a, 32a are arranged side by side along the circumferential direction of the inner pipe 11, and are formed at the same height as each other.

[0034] At portions of the supply pipes 31a, 32a located within the inner pipe 11, a plurality of discharge ports 31f, 32f are provided, respectively.

[0035] The outlets 31f, 32f are formed at predetermined intervals along the extension direction of the respective supply pipes 31a, 32a. The outlets 31f, 32f discharge gas in the horizontal direction. The interval between the outlets 31f, 32f is set to be the same as the interval between the substrates W held in the boat 16, for example. The positions of the outlets 31f, 32f in the height direction are set to the intermediate position between the substrates W adjacent in the vertical direction. In this case, the gas can be efficiently supplied to the opposing surfaces between the adjacent substrates W.

[0036] The gas supply unit 30 may mix a plurality of types of gases and discharge the mixed gas from one supply pipe. The supply pipes 31a and 32a may have different shapes and arrangements. The gas supply unit 30 may supply other gases, such as nitrogen (N 2 The apparatus may further include a supply pipe for supplying an inert gas such as an inert gas.

[0037] The exhaust unit 40 exhausts gas that is exhausted from the inner tube 11 through the opening 15 and then exhausted from a gas outlet 41 through a space P1 between the inner tube 11 and the outer tube 12. The gas outlet 41 is formed in an upper side wall of the manifold 17, above the support unit 20. An exhaust passage 42 is connected to the gas outlet 41. A pressure adjustment valve 43 and a vacuum pump 44 are sequentially provided in the exhaust passage 42, so that the inside of the processing vessel 10 can be exhausted.

[0038] The heating part 50 is provided around the outer tube 12. The heating part 50 is provided, for example, on the base plate 28. The heating part 50 has a cylindrical shape so as to cover the outer tube 12. The heating part 50 includes, for example, a heating element, and heats each substrate W in the processing vessel 10.

[0039] 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. A computer program for controlling the operation of each part of the substrate processing apparatus 1 is stored in a storage medium 90. The storage medium 90 may be, for example, a flexible disk, a compact disk, a hard disk, a flash memory, a DVD, or the like.

[0040] [Operation of the Substrate Processing Apparatus] The operation of the substrate processing apparatus 1 when carrying out the substrate processing method according to the embodiment will be described.

[0041] First, the control unit 80 controls the lifting mechanism 25 to load the boat 16 holding the substrates W into the processing vessel 10, and hermetically closes the opening at the bottom of the processing vessel 10 with the lid 21. Next, the control unit 80 controls the exhaust unit 40 to reduce the pressure inside the processing vessel 10, and controls the heating unit 50 to adjust the temperature of the substrates W to the first film formation temperature. Each substrate W may be the substrate 100 described above.

[0042] Next, the control unit 80 controls the heating unit 50 to maintain the temperature of the substrate W at the first film formation temperature, controls the gas supply unit 30 to supply monosilane gas into the processing vessel 10, and controls the exhaust unit 40 to maintain the inside of the processing vessel 10 at a predetermined pressure. As a result, a non-doped silicon film 102 is formed on the underlayer 101. When forming the non-doped silicon film 102, an inert gas such as nitrogen gas may be supplied into the processing vessel 10 together with the monosilane gas.

[0043] Next, the control unit 80 controls the heating unit 50 to adjust the temperature of the substrate W from the first film formation temperature to the second film formation temperature. Next, the control unit 80 controls the heating unit 50 to maintain the temperature of the substrate W at the second film formation temperature, controls the gas supply unit 30 to supply monosilane gas and phosphine gas into the processing vessel 10, and controls the exhaust unit 40 to maintain the inside of the processing vessel 10 at a predetermined pressure. As a result, a phosphorus-doped silicon film 103 is formed on the non-doped silicon film 102. When forming the phosphorus-doped silicon film 103, an inert gas such as nitrogen gas may be supplied into the processing vessel 10 together with the monosilane gas and phosphine gas. The second film formation temperature may be, for example, the same temperature as the first film formation temperature.

[0044] Next, the control unit 80 controls the heating unit 50 to adjust the temperature of the substrate W from the second film formation temperature to the etching temperature. Next, the control unit 80 controls the heating unit 50 to maintain the temperature of the substrate W at the etching temperature, and controls the gas supply unit 30 to supply chlorine gas into the processing vessel 10, and controls the exhaust unit 40 to maintain the inside of the processing vessel 10 at a predetermined pressure. As a result, the phosphorus-doped silicon film 103 of the non-doped silicon film 102 and the phosphorus-doped silicon film 103 is selectively etched and removed.

[0045] Next, control unit 80 increases the pressure inside processing vessel 10 to atmospheric pressure and decreases the temperature inside processing vessel 10 to the unloading temperature, and then controls lifting mechanism 25 to unload boat 16 from processing vessel 10 .

[0046] [Example] Example 1 First, a substrate in which a phosphorus-doped amorphous silicon film was formed on a silicon oxide film (hereinafter referred to as "Sample A") and a substrate in which a non-doped amorphous silicon film was formed on a silicon oxide film (hereinafter referred to as "Sample B") were prepared. The phosphorus-doped amorphous silicon film had a phosphorus concentration of 1×10 21 atoms / cm 3 It is.

[0047] Next, the native oxide films on the surfaces of samples A and B were removed using DHF.

[0048] Next, the temperature dependence of the etching rates of the phosphorus-doped amorphous silicon film and the non-doped amorphous silicon film when chlorine gas was supplied to the samples A and B using the above-mentioned substrate processing apparatus 1 was evaluated.

[0049] Fig. 4 is a diagram showing the measurement results of the etching rate of the amorphous silicon film. In Fig. 4, the horizontal axis indicates the substrate temperature [°C], and the vertical axis indicates the etching rate [nm / min] of the amorphous silicon film. In Fig. 4, the etching rate of the phosphorus-doped amorphous silicon film is indicated by a triangle symbol, and the etching rate of the non-doped amorphous silicon film is indicated by a circle symbol.

[0050] As shown in Figure 4, the etching rate of the phosphorus-doped amorphous silicon film is several tens of times higher than that of the non-doped amorphous silicon film. This result shows that by doping the non-doped amorphous silicon film with phosphorus, a part of the amorphous silicon film (the area doped with phosphorus) can be selectively removed.

[0051] Example 2 First, a substrate in which a phosphorus-doped polysilicon film was formed on a silicon oxide film (hereinafter referred to as "Sample C") and a substrate in which a non-doped polysilicon film was formed on a silicon oxide film (hereinafter referred to as "Sample D") were prepared. The phosphorus-doped polysilicon film had a phosphorus concentration of 1×10 21 atoms / cm 3 The phosphorus-doped amorphous silicon film was crystallized by heat treatment to form the non-doped polysilicon film. The non-doped amorphous silicon film was crystallized by heat treatment to form the non-doped polysilicon film.

[0052] Next, the native oxide films on the surfaces of samples C and D were removed using DHF.

[0053] Next, the temperature dependence of the etching rates of the phosphorus-doped polysilicon film and the non-doped polysilicon film when chlorine gas was supplied to the samples C and D using the above-mentioned substrate processing apparatus 1 was evaluated.

[0054] Fig. 5 is a diagram showing the measurement results of the etching rate of the polysilicon film. In Fig. 5, the horizontal axis indicates the substrate temperature [°C], and the vertical axis indicates the etching rate [nm / min] of the polysilicon film. In Fig. 5, the etching rate of the phosphorus-doped polysilicon film is indicated by triangles, and the etching rate of the non-doped polysilicon film is indicated by circles.

[0055] 5, it can be seen that the etching rate of the phosphorus-doped polysilicon film is about several tens to several hundreds times higher than that of the non-doped polysilicon film. This result shows that by doping the non-doped polysilicon film with phosphorus, a part of the polysilicon film (the region doped with phosphorus) can be selectively removed.

[0056] 4 and 5, when a polysilicon film is used, the etching selectivity of the phosphorus-doped silicon film to the non-doped silicon film is higher than when an amorphous silicon film is used. Therefore, from the viewpoint of ensuring a high etching selectivity, it is preferable that the silicon film is a polysilicon film.

[0057] 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.

[0058] In the above embodiment, the silicon-containing gas is monosilane gas, but the present disclosure is not limited thereto. For example, the silicon-containing gas may be disilane (Si 2 H 6 ) gas, trisilane (Si 3 H 8 ) gas, tetrasilane (Si 4 H 10For example, the silicon-containing gas may be a mixed gas of two or more of a monosilane gas and a higher order silane gas.

[0059] In the above embodiment, the halogen gas is chlorine gas, but the present disclosure is not limited thereto. For example, the halogen gas may be fluorine (F 2 ) gas, bromine (Br 2 ) gas. [Explanation of symbols]

[0060] 100 Substrates 102 Non-doped silicon film 103 Phosphorus-doped silicon film

Claims

1. preparing a substrate including a non-doped silicon film and a phosphorus-doped silicon film, at least the phosphorus-doped silicon film being exposed on a surface; supplying a halogen gas to the substrate, and selectively etching and removing the phosphorus-doped silicon film from the non-doped silicon film and the phosphorus-doped silicon film; The substrate processing method comprises:

2. The preparing step includes forming the phosphorus-doped silicon film on the non-doped silicon film. The method for processing a substrate according to claim 1 .

3. The phosphorus-doped silicon film is formed by a CVD method using a silicon-containing gas and a phosphorus-containing gas. The substrate processing method according to claim 2 .

4. The preparing step includes modifying a surface layer of the non-doped silicon film to form the phosphorus-doped silicon film; The method for processing a substrate according to claim 1 .

5. the non-doped silicon film is a non-doped polysilicon film, The phosphorus-doped silicon film is a phosphorus-doped polysilicon film. The substrate processing method according to claim 1 .

6. The halogen gas is chlorine gas. The substrate processing method according to claim 5 .

7. The removing step includes maintaining the substrate at a temperature of 200° C. or more and 400° C. or less. The substrate processing method according to claim 6 .

8. a processing vessel for accommodating a substrate; a gas supply unit for supplying a processing gas into the processing vessel; A control unit; Equipped with The control unit is preparing a substrate including a non-doped silicon film and a phosphorus-doped silicon film, at least the phosphorus-doped silicon film being exposed on a surface; supplying a halogen gas to the substrate, and selectively etching and removing the phosphorus-doped silicon film from the non-doped silicon film and the phosphorus-doped silicon film; The gas supply unit is configured to control the gas supply unit to Substrate processing equipment.

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