Film forming method, processing apparatus and processing system

Abstract

To provide a technology capable of suppressing generation of voids in embedding a film into a recess having a narrow part.SOLUTION: A film forming method for embedding a film into a recess including a narrow part of a substrate on which the recess is formed includes the steps of: (a) forming a film at the recess under a condition that the film has greater thickness at the recess's opening than that at its bottom; (b) forming a film at the recess under a condition that the film has the same thickness at the recess's opening as that at its bottom or under a condition that the film has greater thickness at the recess's bottom than that at its opening; and partially etching the film formed at the recess. Multiple cycles each including the step (b) and the step (c) are performed.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In the semiconductor manufacturing process, as structures become finer, there is a demand for filling recesses with a film without leaving any voids (gaps) in recesses with a high aspect ratio. As an example of the process for filling a recess with a film, a technique is known in which a film is filled from the bottom up by alternately repeating deposition and etching (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-112668 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique capable of suppressing the occurrence of voids when a film is embedded in a recess having a narrowed portion. [Means for solving the problem]

[0005] A film formation method according to one aspect of the present disclosure is a film formation method for filling a film in a recess of a substrate having a recess including a narrowed portion, the method comprising: (a) A process for forming a first SiN film in the recess by ALD, the process comprising the steps of: supplying a silicon-containing gas to the substrate; 2 or alternately repeating a step of supplying a silicon-containing gas to the substrate in a supply-rate-limited state and a step of supplying a nitrogen-containing gas to the substrate, thereby forming the first SiN film thicker at the opening of the recess than at the bottom of the recess; (b) a step of forming a second SiN film in the recess by ALD, the second SiN film being formed by thermal ALD in which a silicon-containing gas is reacted with a nitrogen-containing gas by heat, or by plasma ALD in which a silicon-containing gas is reacted with a nitrogen-containing gas with the assistance of plasma, thereby forming the second SiN film to the same thickness at the bottom and the opening of the recess, or forming the second SiN film to be thicker at the bottom than at the opening of the recess; (c) the recess formed The first SiN film and the second SiN and a step of partially etching the film, wherein a plurality of cycles each including the step (b) and the step (c) are performed. Effect of the Invention

[0006] According to the present disclosure, it is possible to suppress the occurrence of voids when a film is embedded in a recess having a narrowed portion. [Brief description of the drawings]

[0007] [Figure 1] 1 is a flowchart showing an example of a film forming method according to an embodiment. [Diagram 2] 1 is a cross-sectional view showing a process of an example of a film forming method according to an embodiment; [Diagram 3] FIG. 1 is a diagram showing an example of a processing system for carrying out a film forming method according to an embodiment. [Figure 4] FIG. 1 is a diagram showing an example of a processing apparatus for carrying out a film forming method according to an embodiment. [Diagram 5] Figure (1) shows the results of forming a SiN film in a recess under low coverage conditions. [Figure 6] Figure (2) shows the results of forming a SiN film in a recess under low coverage conditions. [Figure 7] FIG. 1 is a diagram for explaining the embedding characteristics when a film is embedded in a recess including a narrowed portion by a conventional film formation method. 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] Embedding Process In the semiconductor manufacturing process, as structures become finer, there is a demand for filling recesses with a film without creating voids (gaps) in recesses with high aspect ratios. One known process for filling a recess with a film is a technology that fills the recess with a film from the bottom up by alternately repeating deposition and etching (hereinafter referred to as the "DED process"). By using the DED process, it is possible to suppress the occurrence of voids.

[0010] However, when a film is embedded in a recess of a substrate having a recess including a narrowed portion formed therein using the DED process, damage to the base may occur at the opening of the recess. The reason why damage to the base may occur will be explained below with reference to Fig. 7. Fig. 7 is a diagram for explaining the embedding characteristics when a film is embedded in a recess including a narrowed portion using a conventional film formation method.

[0011] Fig. 7(a) is a schematic cross-sectional view of a substrate in which a recess including a narrowed portion is formed. As shown in Fig. 7(a), a substrate 900 has a base 920 in which a recess 910 is formed. The recess 910 includes an opening 911, a narrowed portion 912, and a bottom 913. The opening 911 is an open portion at the top of the recess 910. The narrowed portion 912 is formed midway from the opening 911 to the bottom 913, and is a portion having a narrower width in cross-sectional view than the opening 911 and the bottom 913. The bottom 913 is a portion including a bottom surface 914 of the recess 910 at the lower portion of the recess 910.

[0012] Fig. 7(b) is a schematic cross-sectional view of the substrate when a film is formed conformally in the recess shown in Fig. 7(a), showing the state after deposition in the DED process. As shown in Fig. 7(b), a film 930 is formed conformally in the recess 910 of the substrate 900 to such an extent that the narrowed portion 912 is not blocked.

[0013] FIG. 7(c) is a schematic cross-sectional view of a substrate when dry etching is performed on the substrate on which a film is conformally formed in a recess, showing a state after etching in the DED process. As shown in FIG. 7(c), in a substrate 900 on which a recess 910 including a narrow portion 912 is formed, it is preferable to remove the film 930 deposited on the narrow portion 912 by etching so that the film 930 is embedded in the bottom portion 913 by deposition after etching. Meanwhile, in the etching of the DED process, the film 930 formed conformally in the recess 910 is etched in a V-shape in cross section. That is, the etching is performed under conditions in which the etching rate for the film 930 is higher in the opening 911 than in the bottom portion 913. Therefore, before removing the film 930 deposited on the narrow portion 912, the film 930 deposited on the opening 911 is removed. Then, if dry etching is continued in a state in which the film 930 deposited on the opening 911 is removed, damage to the base 920 occurs, such as a part of the base 920 being scraped off. This is because the selectivity to the underlying layer is not infinite.

[0014] Hereinafter, a film forming method according to an embodiment will be described, which can fill a recess having a narrowed portion with a film without voids while suppressing damage to the base.

[0015] [Film formation method] An example of a film forming method according to an embodiment will be described with reference to Figures 1 and 2. In the following, a case where a silicon nitride film (SiN film) is formed in a recess and filled in will be described as an example.

[0016] (Process S1) First, in step S1, a substrate on which a recess including a narrowed portion is formed is prepared. As shown in FIG. 2(a), the substrate 100 has a base 120 on which a recess 110 is formed. The recess 110 includes an opening 111, a narrowed portion 112, and a bottom 113. The opening 111 is an open portion at the top of the recess 110. The narrowed portion 112 is formed midway from the opening 111 to the bottom 113, and is a portion having a narrower width in cross-sectional view than the opening 111 and the bottom 113. The bottom 113 is a portion including a bottom surface 114 of the recess 110 at the bottom of the recess 110. In the illustrated example, the recess 110 has a shape that continuously narrows from the opening 111 toward the narrowed portion 112 and continuously widens from the narrowed portion 112 toward the bottom 113. However, the recess 110 is not limited to the shape shown in the figure, and may have another shape including a narrowed portion 112 between the opening 111 and the bottom 113. The recess 110 is a trench, a hole, etc. The base 120 is made of, for example, silicon or an insulating film, and may partially contain a metal or a metal compound.

[0017] (Process S2) Next, in step S2, as shown in FIG. 2(b), a SiN film 130 is formed in the recess 110 under conditions such that the SiN film 130 is formed thicker in the opening 111 than in the bottom 113 of the recess 110 (hereinafter also referred to as "low coverage conditions").

[0018] Step S2 may include forming a SiN film 130 by, for example, atomic layer deposition (ALD).

[0019] When forming the SiN film 130 by ALD, it is preferable to alternately repeat a step of supplying a silicon-containing gas to the substrate 100 and a step of exposing the substrate 100 to plasma generated from a gas containing N2. In the step of supplying a silicon-containing gas to the substrate 100, the silicon-containing gas is adsorbed to the substrate 100, and in the step of exposing the substrate 100 to plasma generated from a gas containing N2, the silicon-containing gas adsorbed to the substrate 100 is nitrided to form a layer of SiN. Here, radicals in the plasma generated from the gas containing N2 have a short life span and are therefore unlikely to reach the bottom 113 of the recess 110. Therefore, the SiN film 130 formed on the bottom 113 of the recess 110 becomes thinner. As a result, the SiN film 130 can be formed thicker at the opening 111 than at the bottom 113 of the recess 110. The gas containing N2 may be, for example, only N2 gas, and may further contain NH3 and H2. However, from the viewpoint of the large difference in film thickness between the bottom 113 and the opening 111, it is preferable that the N2-containing gas is N2 only.

[0020] In addition, when forming the SiN film 130 by ALD, it is preferable to alternately repeat a step of supplying a silicon-containing gas to the substrate 100 in a supply-rate-limited state and a step of supplying a nitrogen-containing gas to the substrate 100. The supply-rate-limited state means a state in which the amount of processing gas supplied to the processing vessel in which the substrate 100 is accommodated is very small, and the film formation rate is mainly governed by the amount of processing gas supplied. For example, the supply-rate-limited state can be realized by reducing the amount of processing gas supplied and increasing the processing temperature. By supplying the silicon-containing gas to the substrate 100 in a supply-rate-limited state, the silicon-containing gas supplied to the recess 110 is absorbed and consumed by the opening 111 or the narrowed portion 112 before reaching the bottom 113. As a result, the SiN film 130 can be formed thicker at the opening 111 than at the bottom 113 of the recess 110. The gas supplied to the substrate 100 in a supply-rate-limited state is not limited to the silicon-containing gas, but may be a nitrogen-containing gas, or may be both the silicon-containing gas and the nitrogen-containing gas.

[0021] Moreover, when the SiN film 130 is formed by ALD, the process includes a step of forming the SiN film 130, and may include a step of etching the SiN film 130. The process of forming the SiN film 130 includes repeating a cycle including a step of supplying a silicon-containing gas to the substrate 100 and a step of supplying a nitrogen-containing gas to the substrate 100, and may further include a step of exposing the substrate 100 to plasma generated from a gas containing He. In the step of supplying the silicon-containing gas to the substrate 100, the silicon-containing gas is adsorbed to the substrate 100, and in the step of supplying the nitrogen-containing gas to the substrate 100, the silicon-containing gas adsorbed to the substrate 100 is nitrided to form a layer of SiN. In the step of exposing the substrate 100 to plasma generated from a gas containing He, the layer of SiN and / or the SiN film 130 is modified into a film with high etching resistance. Here, in the modification by the plasma generated from the gas containing He, the opening 111 is more likely to be modified into a film with high etching resistance than the bottom 113 of the recess 110. Therefore, in the step of etching the SiN film 130 performed after the step of forming the SiN film 130, the amount of etching of the SiN film 130 at the bottom 113 of the recess 110 is greater than that at the opening 111. As a result, the SiN film 130 can be formed thicker at the opening 111 than at the bottom 113 of the recess 110. The step of supplying the nitrogen-containing gas to the substrate 100 may be changed to a step of exposing the substrate 100 to plasma generated from the nitrogen-containing gas. The gas containing He may contain, for example, Ar. The step of etching the SiN film 130 may be either dry etching or wet etching. When etching the SiN film 130 by dry etching, NF3, CHF-based gas, or the like may be used as the etching gas. Gases such as O2, N2, and H2 may be added to these etching gases. When etching the SiN film 130 by wet etching, diluted hydrofluoric acid (DHF: Diluted HF) or the like may be used.

[0022] Step S2 may also include forming the SiN film 130 by chemical vapor deposition (CVD). By forming the SiN film 130 by CVD, the SiN film 130 can be formed thicker in the opening 111 than in the bottom 113 of the recess 110.

[0023] When the SiN film 130 is formed by CVD, it may include forming the SiN film 130 by thermal CVD (Th-CVD) in which a silicon-containing gas and a nitrogen-containing gas are reacted with each other by heat. That is, it may include forming the SiN film 130 by supplying a silicon-containing gas and a nitrogen-containing gas to the substrate 100.

[0024] In addition, when the SiN film 130 is formed by CVD, the method may include forming the SiN film 130 by plasma-enhanced CVD (PE-CVD) in which a reaction between a silicon-containing gas and a nitrogen-containing gas is performed with the assistance of plasma. That is, the method may include forming the SiN film 130 by exposing the substrate 100 to plasma generated from a silicon-containing gas and a nitrogen-containing gas.

[0025] Furthermore, when forming the SiN film 130 by CVD, it is preferable to supply the silicon-containing gas and the nitrogen-containing gas to the substrate 100 in a supply-rate-controlled state. By supplying the silicon-containing gas and the nitrogen-containing gas to the substrate 100 in a supply-rate-controlled state, the silicon-containing gas and the nitrogen-containing gas supplied to the recess 110 are consumed in the opening 111 and the narrowed portion 112 before reaching the bottom 113. As a result, the SiN film 130 can be formed thicker at the opening 111 than at the bottom 113 of the recess 110.

[0026] The silicon-containing gas used in step S2 can be, for example, one or more gases selected from the group consisting of hexachlorodisilane (HCD), monosilane [SiH4], disilane [Si2H6], dichlorosilane (DCS), hexaethylaminodisilane, hexamethyldisilazane (HMDS), tetrachlorosilane (TCS), disilylanine (DSA), trisilylamine (TSA), bis-tert-butylaminosilane (BTBAS), butylaminosilane, dimethylaminosilane, bis-dimethylaminosilane, tridimethylaminosilane, diethylaminosilane, bis-diethylaminosilane, dipropylaminosilane, diisopropylaminosilane, hexakisethylaminodisilane, and the like.

[0027] The nitrogen-containing gas used in step S2 can be, for example, one or more gases selected from the group consisting of nitrogen (N2), ammonia (NH3), diazene (N2H2), hydrazine (N2H4), and organic hydrazine compounds such as monomethylhydrazine (CH3(NH)NH2).

[0028] (Process S3) Next, in step S3, as shown in FIG. 2(c), a SiN film 140 is formed in the recess 110 under conditions such that the SiN film 140 is formed to the same thickness at the bottom 113 of the recess 110 and at the opening 111, or is formed to be thicker at the bottom 113 of the recess 110 than at the opening 111.

[0029] Step S3 may include, for example, forming the SiN film 140 by ALD. By forming the SiN film 140 by ALD, the SiN film 140 can be formed to the same thickness (conformal) at the bottom 113 of the recess 110 and the opening 111.

[0030] When the SiN film 140 is formed by ALD, it may include forming the SiN film 140 by thermal ALD (Th-ALD), which heats the reaction between a silicon-containing gas and a nitrogen-containing gas. That is, it may include forming the SiN film 140 by alternately repeating a step of supplying a silicon-containing gas to the substrate 100 and a step of supplying a nitrogen-containing gas to the substrate 100. In the step of supplying the silicon-containing gas to the substrate 100, the silicon-containing gas is adsorbed to the substrate 100, and in the step of supplying the nitrogen-containing gas to the substrate 100, the silicon-containing gas adsorbed to the substrate 100 is nitrided to form a SiN layer. As the nitrogen-containing gas used in thermal ALD, NH3, N2H4, etc. can be used.

[0031] In addition, when the SiN film 140 is formed by ALD, the method may include forming the SiN film 140 by plasma ALD (PE-ALD), in which a reaction between a silicon-containing gas and a nitrogen-containing gas is performed with the assistance of plasma. That is, the method may include alternately repeating a step of supplying a silicon-containing gas to the substrate 100 and a step of exposing the substrate 100 to plasma generated from a gas containing a nitrogen-containing gas. As the nitrogen-containing gas used in the plasma ALD, for example, one or more gases selected from the group consisting of NH3, N2 / H2, and NH3 / N2 / H2 can be used. A rare gas may be added to the nitrogen-containing gas.

[0032] Furthermore, when the SiN film 140 is formed by ALD, the SiN layer and / or the SiN film 140 may be modified to a film with high etching resistance by exposing the substrate 100 to plasma generated from a modifying gas. That is, the method may include repeating a step of supplying a silicon-containing gas to the substrate 100, a step of exposing the substrate 100 to plasma generated from a gas including a nitrogen-containing gas, and a step of exposing the substrate 100 to plasma generated from the modifying gas. Examples of the modifying gas include He and H2.

[0033] Moreover, the step S3 may include a step of forming an inhibition region that inhibits deposition of the SiN film on the side of the recess 110 that opens upward from the narrowed portion 112 (i.e., the opening 111 side that is shallower than the narrowed portion 112). This inhibits deposition of the SiN film 140 on the opening 111 of the recess 110, so that the SiN film 140 can be formed thicker on the bottom 113 of the recess 110 than on the opening 111. The step of forming the inhibition region may include exposing the substrate 100 to plasma generated from a gas containing, for example, halogen. Examples of the gas containing halogen that can be used include fluorine gas (F2), chlorine gas (Cl2), and hydrogen fluoride gas (HF). The step of forming the inhibition region may include exposing the substrate 100 to plasma generated from a gas containing, for example, N2.

[0034] The silicon-containing gas used in step S3 may be the same as the silicon-containing gas used in step S2, and may be, for example, silicon halide or aminosilane.

[0035] (Process S4) 2(d), the SiN films 130, 140 formed in the recess 110 are etched under etching conditions that make the etching rate of the opening 111 faster than that of the bottom 113, thereby partially removing the SiN films 130, 140. This causes the opening 111 and the narrowed portion 112 to expand, so that the SiN film 140 can be embedded on the bottom 113 side of the narrowed portion 112 in step S3, which is performed again later.

[0036] In step S4, the SiN films 130 and 140 are etched under conditions in which the etching rate of the SiN film 130 is higher in the opening 111 than in the bottom 113, so that the amount of etching of the SiN films 130 and 140 is greater in the opening 111 than in the narrowing portion 112. Therefore, before removing the SiN films 130 and 140 formed in the narrowing portion 112, the SiN films 130 and 140 formed in the opening 111 may be removed, exposing the base 120. However, in this embodiment, in step S2, the SiN film 130 is formed thicker in the opening 111 than in the bottom 113 of the recess 110. This makes it possible to prevent the SiN films 130 and 140 formed in the opening 111 from being removed before the SiN films 130 and 140 formed in the narrowing portion 112 are removed. Therefore, it is possible to prevent the base 120 from being exposed in the opening 111. As a result, even if the selectivity to the underlayer is not infinite, damage to the underlayer 120 in the opening 111 can be suppressed.

[0037] Step S4 may include supplying NF3 or CHF-based gas to the substrate 100. This allows the SiN films 130, 140 formed in the recess 110 to be etched under etching conditions in which the etching rate of the opening 111 is higher than that of the bottom 113.

[0038] Step S4 may also include supplying NF3 or CHF-based gas to the substrate 100 in a rate-limited state. This allows the SiN films 130, 140 formed in the recess 110 to be etched under etching conditions in which the etching rate of the opening 111 is higher than that of the bottom 113.

[0039] (Process S5) Next, in step S5, it is determined whether the number of repetitions of the cycle including steps S3 and S4 has reached a predetermined number. If the number of repetitions of the cycle including steps S3 and S4 has not reached the predetermined number, steps S3 and S4 are performed again. That is, the formation of the SiN film 140 having a conformal or thin opening 111 and the etching of the SiN films 130 and 140 are repeated until the predetermined number is reached. As a result, as shown in FIG. 2(e), the SiN film 140 can be embedded void-free on the bottom 113 side of the narrowed portion 112 in the recess 110. If the number of repetitions of the cycle including steps S3 and S4 has reached the predetermined number, the process proceeds to step S6. The predetermined number is one or more times.

[0040] Furthermore, in the case where the SiN film 130 formed in the opening 111 is removed in step S4 to expose the underlayer 120 or there is a possibility that the underlayer 120 will be exposed, step S2 may be performed after step S4 and before step S3 while steps S3 and S4 are being repeated. That is, a part of a plurality of cycles each including steps S3 and S4 may include step S2.

[0041] (Process S6) Next, in step S6, a SiN film 140 is formed in the recess 110 under the condition that the SiN film 140 is formed to the same thickness at the bottom 113 of the recess 110 and at the opening 111, or under the condition that the SiN film 140 is formed to be thicker at the bottom 113 than at the opening 111 of the recess 110. This allows the SiN film 140 to be embedded in the recess 110 without voids, as shown in FIG. 2(f).

[0042] Step S6 may include forming the SiN film 140 by, for example, ALD. By forming the SiN film 140 by ALD, the SiN film 140 can be formed to the same thickness (conformal) at the bottom 113 of the recess 110 and the opening 111. Furthermore, by forming the SiN film 140 by ALD, the SiN film 140 can be formed such that the bottom 113 is thicker than the opening 111 of the recess 110. The method of forming the SiN film 140 by ALD may be the same as the method of forming the SiN film 140 by ALD in step S3.

[0043] According to the embodiment described above, a SiN film is formed under low coverage conditions on a substrate on which a recess including a narrowed portion is formed, and then the SiN film is filled into the recess by repeating the formation of a conformal or thin-opening SiN film and the etching of the SiN film. As a result, the SiN film formed under low coverage conditions functions as a protective film that prevents the exposure of the underlayer during the etching of the SiN film. As a result, damage to the underlayer during the etching of the SiN film can be suppressed. In addition, since the SiN film is formed in the recess while repeating the formation of a conformal or thin-opening SiN film and the etching of the SiN film, the clogging of the narrowed portion can be prevented. As a result, the generation of voids during the filling of the recess with a film can be suppressed.

[0044] [Processing System] An example of a processing system for carrying out the film forming method of the embodiment will be described with reference to FIG.

[0045] The processing system PS includes processing devices PM1 to PM4, a vacuum transfer chamber VTM, load lock chambers LL1 to LL3, an atmospheric transfer chamber LM, load ports LP1 to LP3, and a general control unit CU0.

[0046] The processing devices PM1 to PM4 are connected to the vacuum transfer chamber VTM via gate valves G11 to G14, respectively. The interiors of the processing devices PM1 to PM4 are depressurized to a predetermined vacuum atmosphere, and the substrates W are subjected to a desired processing therein.

[0047] The inside of the vacuum transfer chamber VTM is depressurized to a predetermined vacuum atmosphere. The vacuum transfer chamber VTM is provided with a transfer mechanism TR1 capable of transferring the substrate W in a depressurized state. The transfer mechanism TR1 transfers the substrate W to the processing devices PM1 to PM4 and the load lock chambers LL1 to LL3. The transfer mechanism TR1 has, for example, two transfer arms FK11 and FK12 that can move independently.

[0048] The load lock chambers LL1 to LL3 are connected to the vacuum transfer chamber VTM via gate valves G21 to G23, respectively, and are connected to the atmospheric transfer chamber LM via gate valves G31 to G33. The interiors of the load lock chambers LL1 to LL3 can be switched between an atmospheric atmosphere and a vacuum atmosphere.

[0049] The atmosphere inside the atmospheric transfer chamber LM is atmospheric, and for example, a downflow of clean air is formed. An aligner AN that aligns the substrate W is provided inside the atmospheric transfer chamber LM. A transfer mechanism TR2 is also provided in the atmospheric transfer chamber LM. The transfer mechanism TR2 transfers the substrate W to the load lock chambers LL1 to LL3, the carriers C of the load ports LP1 to LP3 described below, and the aligner AN.

[0050] The load ports LP1 to LP3 are provided on the long side wall of the atmospheric transfer chamber LM. The load ports LP1 to LP3 are fitted with carriers C accommodating substrates W or empty carriers C. As the carriers C, for example, a FOUP (Front Opening Unified Pod) can be used.

[0051] The overall control unit CU may be, for example, a computer. The overall control unit CU includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), an auxiliary storage device, etc. The CPU operates based on a program stored in the ROM or the auxiliary storage device, and controls each part of the processing system PS. For example, the overall control unit CU executes operations of the processing devices PM1 to PM4, the transport mechanisms TR1 and TR2, opening and closing of the gate valves G11 to G14, G21 to G23, and G31 to G33, switching of the atmosphere in the load lock chambers LL1 to LL3, etc.

[0052] In the processing system PS of the embodiment, at least one of the processing devices PM1 to PM4 is used to continuously perform the steps S2 to S4, and S6 in the film forming method of the embodiment under a reduced pressure atmosphere. For example, the steps S2 to S4, and S6 may be continuously performed using one of the processing devices PM1 to PM4. Alternatively, for example, the steps S2 and S3 may be continuously performed using one of the processing devices PM1 to PM4, the step S4 may be performed using another one, and the step S6 may be performed using yet another one. Alternatively, for example, the processing devices PM1 to PM4 may each perform different steps S2 to S4, and S6.

[0053] [Processing Device] With reference to FIG. 4, an example of a processing apparatus used as the processing apparatuses PM1 to PM4 included in the processing system PS of FIG. 3 will be described.

[0054] The processing apparatus includes a processing vessel 1, a mounting table 2, a shower head 3, an exhaust unit 4, a gas supply unit 5, an RF power supply unit 8, a control unit 9, and the like.

[0055] The processing vessel 1 is made of a metal such as aluminum and has a substantially cylindrical shape. The processing vessel 1 accommodates a substrate W. The substrate W is, for example, a semiconductor wafer. A loading / unloading port 11 is formed in a side wall of the processing vessel 1 for loading or unloading the substrate W. The loading / unloading port 11 is opened and closed by a gate valve 12. An annular exhaust duct 13 having a rectangular cross section is provided on the main body of the processing vessel 1. A slit 13a is formed along the inner peripheral surface of the exhaust duct 13. An exhaust port 13b is formed in the outer wall of the exhaust duct 13. A top wall 14 is provided on the upper surface of the exhaust duct 13 so as to close the upper opening of the processing vessel 1 via an insulating member 16. A seal ring 15 is used to hermetically seal the space between the exhaust duct 13 and the insulating member 16. The partition member 17 partitions the inside of the processing vessel 1 into upper and lower sections when the mounting table 2 (and the cover member 22) is raised to a processing position described later.

[0056] The mounting table 2 horizontally supports the substrate W in the processing chamber 1. The mounting table 2 is formed in a disk shape having a size corresponding to the substrate W, and is supported by a support member 23. The mounting table 2 is made of a ceramic material such as AlN or a metal material such as an aluminum or nickel alloy, and has a heater 21 embedded therein for heating the substrate W. The heater 21 generates heat when power is supplied from a heater power source (not shown). The output of the heater 21 is controlled by a temperature signal from a thermocouple (not shown) provided near the upper surface of the mounting table 2, thereby controlling the substrate W to a predetermined temperature. The mounting table 2 is provided with a cover member 22 made of ceramic such as alumina so as to cover the outer circumferential region of the upper surface and the side surfaces.

[0057] A support member 23 for supporting the mounting table 2 is provided on the bottom surface of the mounting table 2. The support member 23 extends from the center of the bottom surface of the mounting table 2 through a hole formed in the bottom wall of the processing vessel 1 to below the processing vessel 1, and its lower end is connected to a lifting mechanism 24. The lifting mechanism 24 raises and lowers the mounting table 2 via the support member 23 between a processing position shown in FIG. 1 and a transfer position shown by a two-dot chain line below the processing position where the substrate W can be transferred. A flange 25 is attached to the support member 23 below the processing vessel 1. A bellows 26 is provided between the bottom surface of the processing vessel 1 and the flange 25. The bellows 26 separates the atmosphere inside the processing vessel 1 from the outside air, and expands and contracts with the lifting and lowering operation of the mounting table 2.

[0058] Three wafer support pins 27 (only two shown) are provided near the bottom surface of the processing vessel 1 so as to protrude upward from a lift plate 27a. The wafer support pins 27 are raised and lowered via the lift plate 27a by a lift mechanism 28 provided below the processing vessel 1. The wafer support pins 27 are inserted into through holes 2a provided in the mounting table 2 at the transfer position, and can be protruded and retracted from the upper surface of the mounting table 2. The substrate W is transferred between the transfer mechanism (not shown) and the mounting table 2 by raising and lowering the wafer support pins 27.

[0059] The shower head 3 supplies a processing gas into the processing vessel 1 in a shower-like manner. The shower head 3 is made of metal, is provided to face the mounting table 2, and has approximately the same diameter as the mounting table 2. The shower head 3 has a main body 31 and a shower plate 32. The main body 31 is fixed to the ceiling wall 14 of the processing vessel 1. The shower plate 32 is connected below the main body 31. A gas diffusion space 33 is formed between the main body 31 and the shower plate 32. A gas introduction hole 36 is provided in the gas diffusion space 33 so as to penetrate the center of the ceiling wall 14 and the main body 31 of the processing vessel 1. An annular protrusion 34 protruding downward is formed on the periphery of the shower plate 32. A gas discharge hole 35 is formed on the inner flat portion of the annular protrusion 34. When the mounting table 2 is in the processing position, a processing space 38 is formed between the mounting table 2 and the shower plate 32, and the upper surface of the cover member 22 and the annular protrusion 34 are close to each other to form an annular gap 39.

[0060] The exhaust unit 4 exhausts the inside of the processing vessel 1. The exhaust unit 4 has an exhaust pipe 41 connected to the exhaust port 13b, and an exhaust mechanism 42 having a vacuum pump, a pressure control valve, etc. connected to the exhaust pipe 41. During processing, gas inside the processing vessel 1 reaches the exhaust duct 13 through the slit 13a, and is exhausted by the exhaust mechanism 42 from the exhaust duct 13 through the exhaust pipe 41.

[0061] The gas supply unit 5 supplies various process gases to the shower head 3. The gas supply unit 5 includes a gas source 51 and a gas line 52. The gas source 51 includes, for example, a supply source of various process gases, a mass flow controller, and a valve (none of which are shown). The various process gases include the gases used in the film forming method of the above-mentioned embodiment. The various gases are introduced from the gas source 51 through the gas line 52 and the gas introduction hole 36 into the gas diffusion space 33.

[0062] The processing apparatus is a capacitively coupled plasma apparatus, in which the mounting table 2 functions as a lower electrode and the shower head 3 functions as an upper electrode. The mounting table 2 is grounded via a capacitor (not shown). However, the mounting table 2 may be grounded, for example, without a capacitor, or may be grounded via a circuit combining a capacitor and a coil. The shower head 3 is connected to an RF power supply unit 8.

[0063] The RF power supply unit 8 supplies high frequency power (hereinafter also referred to as "RF power") to the shower head 3. The RF power supply unit 8 includes an RF power source 81, a matching box 82, and a feed line 83. The RF power source 81 is a power source that generates RF power. The RF power has a frequency suitable for generating plasma. The frequency of the RF power is, for example, within a range from 450 KHz in the low frequency band to 2.45 GHz in the microwave band. The RF power source 81 is connected to the main body 31 of the shower head 3 via the matching box 82 and the feed line 83. The matching box 82 includes a circuit for matching the load impedance to the internal impedance of the RF power source 81. Note that the RF power supply unit 8 has been described as supplying RF power to the shower head 3 serving as the upper electrode, but is not limited thereto. It may be configured to supply RF power to the mounting table 2 serving as the lower electrode.

[0064] The control unit 9 is, for example, a computer, and includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), an auxiliary storage device, etc. The CPU operates based on a program stored in the ROM or the auxiliary storage device, and controls the operation of the processing device. The control unit 9 may be provided inside the processing device, or may be provided externally. When the control unit 9 is provided externally to the processing device, the control unit 9 can control the processing device via a communication means such as a wired or wireless communication means.

[0065] [Evaluation results] 5 and 6, a SiN film was formed in a recess (trench) under the low coverage conditions used in step S2 of the film forming method of the embodiment, and the formed SiN film was observed with an electron microscope.

[0066] First, a substrate was prepared that included a recess formed of an amorphous silicon (a-Si) film on a SiN film. Next, a SiN film was formed in the recess under low coverage conditions by alternately repeating a step of supplying a silicon-containing gas to the substrate and a step of exposing the substrate to plasma generated from a gas containing N2. Bisdiethylaminosilane (BDEAS) was used as the silicon-containing gas. A mixed gas of N2 and Ar was used as the N2-containing gas. Specifically, in a processing apparatus as shown in FIG. 4, for example, a pressure of 0.1 to 50 Torr (1.3×10 1 ~6.7×10 3 A SiN film was formed in the recess by alternately repeating a step of supplying BDEAS at a specific flow rate for 0.05 to 1.0 seconds while maintaining the pressure at 1 Pa and a step of exposing the recess to plasma with a power of 10 to 1000 W generated from a specific flow rate of N for 0.1 to 6.0 seconds.

[0067] FIG. 5 shows the results of forming a SiN film in a recess under low coverage conditions, and shows the results of observation with a scanning electron microscope (SEM).

[0068] As shown in Figure 5, it can be seen that the SiN film is formed thicker at the opening than at the bottom of the recess. This result shows that by alternately repeating the step of supplying a silicon-containing gas to the substrate and the step of exposing the substrate to plasma generated from a gas containing N2, it is possible to form a SiN film thicker at the opening than at the bottom of the recess.

[0069] Next, a substrate including a recess formed of crystalline silicon (Si) was prepared. Then, under low coverage conditions, a step of forming a SiN film and a step of etching the SiN film were performed in this order to form a SiN film in the recess. In the step of forming the SiN film, a cycle including a step of supplying a silicon-containing gas to the substrate, a step of exposing the substrate to plasma generated from a nitrogen-containing gas, and a step of exposing the substrate to plasma generated from a gas containing He was repeated. In the step of etching the SiN film, wet etching was performed using dilute hydrofluoric acid. Dichlorosilane (DCS) was used as the silicon-containing gas. NH3 was used as the nitrogen-containing gas. A mixed gas of He and Ar was used as the He-containing gas. Specifically, in a processing apparatus as shown in FIG. 4, for example, a pressure of 0.1 to 50 Torr (1.3×10 1 ~6.7×10 3 A SiN film was formed in the recess by repeating the steps of supplying DCS at a specific flow rate for 0.05 to 1.0 second while maintaining the pressure at 10 Pa, exposing the sample to plasma with a power of 100 to 3000 W generated from a specific flow rate of NH3 for 1.0 to 10.0 seconds, and exposing the sample to plasma with a power of 10 to 1000 W generated from a specific flow rate of He for 1.0 to 10.0 seconds.

[0070] Fig. 6 shows the results of forming a SiN film in a recess under low coverage conditions, and shows the results of observation by a transmission electron microscope (TEM). Fig. 6(a) shows the results of observation by TEM after the step of forming the SiN film, and Fig. 6(b) shows the results of observation by TEM after the step of etching the SiN film.

[0071] As shown in Fig. 6(a), after the step of forming the SiN film, it can be seen that the SiN film is conformally formed in the recess. Also, as shown in Fig. 6(b), after the step of etching the SiN film, it can be seen that the SiN film formed on the bottom of the recess is almost completely removed, and the SiN film formed on the opening of the recess remains. This result shows that by exposing the substrate to plasma generated from a gas containing He in the step of forming the SiN film, and then etching the SiN film formed in the step of forming the SiN film, it is possible to form a SiN film that is thicker on the opening than on the bottom of the recess.

[0072] 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.

[0073] In the above embodiment, the processing apparatus is a capacitively coupled plasma apparatus, but the present disclosure is not limited to this. For example, the processing apparatus may be a plasma apparatus using an inductively coupled plasma, a surface wave plasma (microwave plasma), a magnetron plasma, a remote plasma, or the like as a plasma source.

[0074] In the above embodiment, as an example of a film forming method, a case where a SiN film is filled in the recess is described, but the present disclosure is not limited to this. For example, the film filled in the recess may be a silicon oxide film (SiO2 film), a metal nitride film, or a metal oxide film.

[0075] In the above embodiment, the processing apparatus is a single-wafer processing apparatus that processes wafers one by one, but the present disclosure is not limited thereto. For example, the processing apparatus may be a batch-type apparatus that processes multiple wafers at once. Also, for example, the processing apparatus may be a semi-batch-type apparatus that processes the wafers by rotating multiple wafers placed on a turntable in a processing vessel by the turntable, and passing the wafers through an area where a first gas is supplied and an area where a second gas is supplied in sequence. Also, the processing apparatus may be a multiple-wafer processing apparatus equipped with multiple placement tables in one processing vessel. [Explanation of symbols]

[0076] 100 Substrates 110 Recess 111 Opening 112 Stenosis 113 Bottom 130 SiN film 140 SiN film

Claims

1. 1. A film forming method for filling a film in a recess of a substrate having a recess including a narrowed portion, the method comprising the steps of: (a) forming a first SiN film in the recess by ALD, the first SiN film being formed thicker at the opening of the recess than at the bottom thereof by alternately repeating a step of supplying a silicon-containing gas to the substrate and a step of exposing the substrate to plasma generated from a gas containing N2, or a step of supplying a silicon-containing gas to the substrate in a supply-rate-limited state and a step of supplying a nitrogen-containing gas to the substrate; (b) forming a second SiN film in the recess by ALD, the second SiN film being formed by thermal ALD in which a silicon-containing gas is reacted with a nitrogen-containing gas by heat, or by plasma ALD in which a silicon-containing gas is reacted with a nitrogen-containing gas by plasma assistance, thereby forming the second SiN film to the same thickness at the bottom and the opening of the recess, or forming the second SiN film to be thicker at the bottom than at the opening of the recess; (c) partially etching the first SiN film and the second SiN film formed in the recess; having performing a plurality of cycles each including step (b) and step (c); Film formation method.

2. At least a portion of the multiple cycles includes step (a). The film forming method according to claim 1 .

3. The step (a) further comprises exposing the substrate to a plasma generated from a gas containing He. The film forming method according to claim 1 .

4. The step (a) further comprises etching the first SiN film. The film forming method according to claim 3 .

5. The nitrogen-containing gas in step (b) is NH ３ , N ２ / H ２ , N.H. ３ / N ２ / H ２ One or more gases selected from The film forming method according to claim 1 .

6. The steps (a), (b) and (c) are successively carried out under a reduced pressure atmosphere. The film forming method according to claim 1 .

7. The method of claim 1, wherein the nitrogen-containing gas in step (a) is N2. The film forming method according to claim 1 .

8. The step (b) further comprises exposing the substrate to a plasma generated from a modifying gas. The film forming method according to claim 1 .

9. The process (b) further includes a step of forming an inhibition region that inhibits deposition of the second SiN film on a side of the recess that opens upwardly above the narrowed portion, The film forming method according to claim 1 .

10. In the step of forming the inhibition region, the substrate is exposed to plasma generated from a gas containing a halogen. The film forming method according to claim 9 .

11. A processing apparatus for performing a film forming method for filling a film in a recess of a substrate having a recess including a narrowed portion, comprising: a processing vessel for accommodating the substrate; a gas supply unit for supplying a processing gas into the processing vessel; A control unit; Equipped with The control unit is (a) forming a first SiN film in the recess by ALD, the first SiN film being formed thicker at the opening of the recess than at the bottom thereof by alternately repeating a step of supplying a silicon-containing gas to the substrate and a step of exposing the substrate to plasma generated from a gas containing N2, or a step of supplying a silicon-containing gas to the substrate in a supply-rate-limited state and a step of supplying a nitrogen-containing gas to the substrate; (b) forming a second SiN film in the recess by ALD, the second SiN film being formed by thermal ALD in which a silicon-containing gas is reacted with a nitrogen-containing gas by heat, or by plasma ALD in which a silicon-containing gas is reacted with a nitrogen-containing gas by plasma assistance, thereby forming the second SiN film to the same thickness at the bottom and the opening of the recess, or forming the second SiN film to be thicker at the bottom than at the opening of the recess; (c) partially etching the first SiN film and the second SiN film formed in the recess; and configured to control the gas supply to perform The control unit is configured to control the gas supply to perform a plurality of cycles, each cycle including steps (b) and (c); Processing unit.

12. A processing system for performing a film forming method for filling a film in a recess of a substrate having a recess including a narrowed portion, comprising: a first deposition module for forming a first SiN film in the recess by ALD, the first deposition module forming the first SiN film thicker at the opening of the recess than at the bottom thereof by alternately repeating a step of supplying a silicon-containing gas to the substrate and a step of exposing the substrate to plasma generated from a gas containing N2, or by alternately repeating a step of supplying a silicon-containing gas to the substrate in a supply-rate-limited state and a step of supplying a nitrogen-containing gas to the substrate; a second film formation module that forms a second SiN film in the recess by ALD, the second SiN film being formed by thermal ALD in which a silicon-containing gas and a nitrogen-containing gas are reacted with heat, or by plasma ALD in which a silicon-containing gas and a nitrogen-containing gas are reacted with assistance of plasma, thereby forming the second SiN film to the same thickness at the bottom and the opening of the recess, or forming the second SiN film to be thicker at the bottom of the recess than at the opening; an etching module that partially etches the first SiN film and the second SiN film formed in the recess; a transfer module that transfers the substrate between the first film deposition module, the second film deposition module, and the etching module under a reduced pressure atmosphere; A processing system comprising:

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