Film forming method and film forming apparatus

Abstract

To control the shape of a silicon-containing film to be formed to a shape that allows a film with good uniformity to be obtained in a recessed portion by ALD deposition.SOLUTION: In a placing step, a substrate on which a pattern having a plurality of unevenness is formed is mounted on a mounting table arranged in a chamber. In a film formation step, bias power is applied to the mounting table, processing gas containing silicon-containing gas and nitrogen-containing gas is supplied into the chamber, and microwaves are introduced into the chamber to generate plasma to selectively form a silicon-containing film on a plurality of convex portions of the pattern. The film formation step includes a first film formation step and a second film formation step. In the first film formation step, the silicon-containing film is formed around the upper sides of the plurality of convex portions. In the second film formation step, the silicon-containing film is formed on the top of the plurality of convex portions.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Patent Document 1 proposes a technology for manufacturing a semiconductor device, in which an adsorption control layer is formed to cover the upper part of a 3D structure formed on a substrate, and a material layer is formed on the adsorption control layer and on the lower part of the 3D structure that is not covered by the adsorption control layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2020 / 0111660 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides techniques for controlling the shape of a deposited silicon-containing film to a shape that results in a film with good uniformity within a feature during ALD deposition. [Means for solving the problem]

[0005] A film forming method according to one embodiment of the present disclosure includes a placing step and a film forming step. In the placing step, a substrate having a pattern with multiple projections and recesses is placed on a mounting table disposed in a chamber. In the film forming step, a bias power is applied to the mounting table, and a process gas containing a silicon-containing gas and a nitrogen-containing gas is supplied into the chamber while a microwave is introduced into the chamber to generate plasma, and a silicon-containing film is selectively formed on multiple projections of the pattern. The film forming step includes a first film forming step and a second film forming step. In the first film forming step, a silicon-containing film is formed around the upper side of the multiple projections. In the second film forming step, a silicon-containing film is formed on the tops of the multiple projections. Effect of the Invention

[0006] According to the present disclosure, the shape of the deposited silicon-containing film can be controlled to a shape that allows for ALD deposition to result in a film with good uniformity within a recess. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view that illustrates an example of a plasma processing apparatus according to an embodiment. [Diagram 2] FIG. 2 is a flowchart showing an example of the flow of the film forming method according to the embodiment. [Diagram 3] FIG. 3 is a diagram illustrating an example of a substrate according to an embodiment. [Figure 4] FIG. 4 is a diagram illustrating a film formation result by the first film formation step and the second film formation step according to the embodiment. [Diagram 5] FIG. 5 is a diagram illustrating the film formation results of the comparative example. [Figure 6] FIG. 6 is a diagram showing an example of a film formation result. [Figure 7] FIG. 7 is a diagram illustrating an example of a subsequent process performed on the substrate. [Figure 8] FIG. 8 is a diagram for explaining film formation using microwave plasma and CCP. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of a film formation method and a film formation apparatus disclosed in the present application will be described in detail with reference to the drawings. Note that the disclosed film formation method and film formation apparatus are not limited to the embodiment.

[0009] In recent years, the aspect ratio of patterns formed on substrates such as semiconductor wafers tends to increase with the miniaturization of semiconductor devices. For example, in the manufacture of 3D NAND, the opening width of trenches and vias formed on substrates is narrowing, and high aspect ratio structures are being developed. ALD (Atomic Layer Deposition) is generally used to conformally form barrier layers and liner layers in such trenches and vias. However, even if ALD deposition, which has excellent step coverage, is used to conformally form barrier layers and liner layers in trenches and vias with high aspect ratio structures, it requires longer adsorption and purging times of source gases than in a normal ALD deposition sequence, which causes a significant problem in throughput (productivity). In a normal ALD deposition sequence, the film thickness is thick at the top of the trench or via and thin at the bottom, which causes problems such as overhangs and poor step coverage.

[0010] Therefore, as disclosed in Patent Document 1, it is conceivable to form an adhesion control layer on the upper part of the pattern by PECVD (Plasma Enhanced Chemical Vapor Deposition) and then form material layers such as a barrier layer and a liner layer by ALD.

[0011] However, PECVD cannot control the shape (profile) of the film to a shape that can be obtained by ALD deposition with good uniformity in the recesses. Therefore, a technology is desired that can control the shape of the deposited silicon-containing film to a shape that can be obtained by ALD deposition with good uniformity in the recesses.

[0012] [Embodiment] [Device configuration] An example of a plasma processing apparatus for carrying out the film forming method of the present disclosure will be described below. Fig. 1 is a cross-sectional view that illustrates a schematic example of a plasma processing apparatus 100 according to an embodiment.

[0013] The plasma processing apparatus 100 includes a chamber 101, a mounting table 102, a gas supply mechanism 103, an exhaust mechanism 104, a microwave plasma source 105, and a control unit .

[0014] The chamber 101 is made of a metal material, for example, aluminum whose surface has been anodized, and has a generally cylindrical shape. The chamber 101 has a plate-shaped top wall portion 111 and bottom wall portion 113, and a side wall portion 112 connecting these. The inner wall of the chamber 101 may be coated with yttria (Y2O3) or the like. A mounting table 102 is disposed inside the chamber 101. The chamber 101 accommodates a substrate W, such as a semiconductor wafer.

[0015] The top wall 111 has a plurality of openings into which a microwave radiation mechanism 143 and a gas introduction nozzle 123, described later, of the microwave plasma source 105 are fitted. The side wall 112 has a load / unload port 114 for loading / unloading the substrate W between the chamber 101 and a transfer chamber (not shown) adjacent to the chamber 101. The load / unload port 114 is adapted to be opened and closed by a gate valve 115. An exhaust pipe 116 is connected to the bottom wall 113.

[0016] The mounting table 102 is formed in a disk shape and is made of a metal material, for example, aluminum whose surface has been anodized, or a ceramic material, for example, aluminum nitride (AlN). The substrate W is placed on the upper surface of the mounting table 102. The mounting table 102 is supported by a support member 120, which is a metallic cylinder extending upward from the center of the bottom of the chamber 101 via an insulating member 121. An electrostatic chuck (not shown) that attracts and holds the substrate W by electrostatic force may be provided on the upper surface of the mounting table 102.

[0017] Inside the mounting table 102, lifting pins (not shown) for lifting and lowering the substrate W are provided so as to be capable of protruding and retracting from the upper surface of the mounting table 102. Furthermore, inside the mounting table 102, a temperature control mechanism (not shown) consisting of a temperature control medium flow path for circulating a temperature control medium, a heater, or both, is provided, making it possible to control the temperature of the substrate W on the mounting table 102 to a predetermined temperature.

[0018] From the viewpoint of performing good plasma processing, it is preferable that the mounting table 102 is located at a position such that the distance from the lower surface of the top wall portion 111, which is the microwave emitting surface of the microwave emitting mechanism 143, to the substrate W is in the range of 40 to 200 mm. The microwave emission frequency of the microwave emitting mechanism 143 is in the range of 300 MHz to 30 GHz, and the input power is preferably 500 W or more to maintain stable plasma.

[0019] A high frequency power supply 122 for attracting ions is electrically connected to the mounting table 102. When the mounting table 102 is made of ceramics, an electrode is provided on the mounting table 102, and the high frequency power supply 122 is electrically connected to the electrode. The high frequency power supply 122 applies radio frequency (RF) power as bias power to the mounting table 102. The frequency of the high frequency power applied by the high frequency power supply 122 is preferably in the range of 300 KHz to 3 MHz.

[0020] The gas supply mechanism 103 supplies various process gases for forming a film into the chamber 101. The gas supply mechanism 103 has a plurality of gas introduction nozzles 123, a gas supply pipe 124, and a gas supply unit 125. The gas introduction nozzles 123 are fitted into openings formed in the ceiling wall 111 of the chamber 101. The gas supply unit 125 is connected to each gas introduction nozzle 123 via the gas supply pipe 124. The gas supply unit 125 supplies various process gases. For example, the gas supply unit 125 has a supply source of various process gases including a silicon-containing gas and a nitrogen-containing gas, and supplies various process gases including a silicon-containing gas and a nitrogen-containing gas. The gas supply unit 125 may further have a supply source of a rare gas and a carbon-containing gas, and further supply the rare gas and the carbon-containing gas as the process gas. The gas supply unit 125 is also provided with an opening / closing valve for starting and stopping the supply of the process gas and a flow rate adjustment unit for adjusting the flow rate of the process gas.

[0021] An exhaust pipe 116 is connected to the bottom wall 113 of the chamber 101. An exhaust mechanism 104 is connected to the exhaust pipe 116. The exhaust mechanism 104 includes a vacuum pump and a pressure control valve, and exhausts air from the chamber 101 via the exhaust pipe 116 using the vacuum pump. The pressure in the chamber 101 is controlled by the pressure control valve based on the value of a pressure gauge.

[0022] The microwave plasma source 105 is provided above the chamber 101. The microwave plasma source 105 introduces electromagnetic waves (microwaves) into the chamber 101 to generate plasma.

[0023] The microwave plasma source 105 has a microwave output section 130 and an antenna unit 140. The antenna unit 140 includes a plurality of antenna modules. In FIG. 1, the antenna unit 140 includes three antenna modules. Each antenna module has an amplifier section 142 and a microwave radiation mechanism 143. The microwave output section 130 generates microwaves and distributes the microwaves to each antenna module. The amplifier section 142 of the antenna module mainly amplifies the distributed microwaves and outputs them to the microwave radiation mechanism 143. The microwave radiation mechanism 143 is provided on the ceiling wall section 111. The microwave radiation mechanism 143 radiates the microwaves output from the amplifier section 142 into the chamber 101.

[0024] 1, an example in which three antenna modules are provided in antenna unit 140 has been described, but the number of antenna modules is not limited thereto. For example, six antenna modules may be provided in an area above mounting base 102 of top wall 111, arranged at the vertices of a regular hexagon. Seven antenna modules may also be provided, arranged at the center of the regular hexagon.

[0025] Furthermore, if the power density of the microwave can be appropriately controlled, a microwave plasma source having a single microwave introduction part having a size corresponding to the substrate W may be used.

[0026] The control unit 106 is, for example, a computer including a processor, a storage unit, an input device, a display device, and the like. The control unit 106 controls each unit of the plasma processing apparatus 100. In the control unit 106, an operator can use the input device to input commands to manage the plasma processing apparatus 100. In addition, the control unit 106 can visualize and display the operating status of the plasma processing apparatus 100 using the display device. Furthermore, the storage unit of the control unit 106 stores a control program for controlling various processes performed in the plasma processing apparatus 100 by the processor, and recipe data. The processor of the control unit 106 executes the control program and controls each unit of the plasma processing apparatus 100 according to the recipe data, so that the desired process is performed in the plasma processing apparatus 100. For example, the control unit 106 controls each unit of the plasma processing apparatus 100 to perform the process of the film forming method according to the embodiment.

[0027] As described above, the aspect ratio of the pattern formed on the substrate W tends to increase with the miniaturization of semiconductor devices. For example, in the manufacture of 3D NAND, the opening width of trenches and vias formed on the substrate W is narrowing, and high aspect ratio structures are being developed. When forming a barrier layer or liner layer conformally in such a trench or via, ALD is generally used. However, when attempting to form a barrier layer or liner layer by ALD in a trench or via with a high aspect ratio structure, the film thickness is thick at the top of the trench or via and thin at the bottom, which causes problems such as overhangs and poor step coverage.

[0028] Therefore, before a process of forming a barrier layer or a liner layer in a trench or a via by ALD, an insulating film such as a silicon-containing film or a carbon-containing film is formed as a structure as an adhesion control layer by the film forming method according to the present embodiment using the plasma processing apparatus 100. Fig. 2 is a flowchart showing an example of the flow of the film forming method according to the embodiment.

[0029] Next, a description will be given of a process operation when the thus configured plasma processing apparatus 100 performs the film formation process of the film formation method according to the embodiment. Fig. 2 is a flow chart showing an example of the flow of the film formation method according to the embodiment.

[0030] In the film forming method according to the embodiment, a placing step S1 is performed. In the placing step S1, a substrate W is placed on a placing table 102 arranged in a chamber 101. The substrate W has a pattern having a plurality of projections and recesses formed thereon. FIG. 3 is a diagram showing an example of the substrate W according to the embodiment. FIG. 3 shows the substrate W having a pattern having projections and recesses formed thereon. Recesses 12 between projections 11 of the substrate W are, for example, trenches or vias.

[0031] In the film forming method according to the embodiment, a film forming step S2 is then performed. In the film forming step S2, a bias power is applied to the mounting table 102, and a process gas containing a silicon-containing gas and a nitrogen-containing gas is supplied into the chamber 101 while a microwave is introduced into the chamber 101 to generate plasma, and a silicon-containing film is selectively formed on the multiple protrusions 11 of the pattern.

[0032] Examples of the silicon-containing gas include silane-based hydrogen gas such as SiH4, Si2H6, or SiH2Cl4, or silane-based halogen gas. Examples of the nitrogen-containing gas include hydrogen nitride gas such as NH3, N2H2, or N3H5, such as ammonia, hydrazine, or triazane, and nitrogen gas N2 alone. In the film-forming step S2, other gases such as a rare gas or a carbon-containing gas may be further supplied as a processing gas. For example, by adding a small amount of carbon-containing gas (for example, about 0.1 to 5 [sccm] of C2H6 gas), it is possible to form a SiCN film with better chemical resistance (wet etching resistance) without changing the SiN shape characteristics in the film-forming step S2. The rare gas may be any monoatomic element that can be expressed in Group 18 of the periodic table, and examples of the rare gas include Ar (argon) gas and He (helium). Examples of the carbon-containing gas include any hydrocarbon gas such as C2H6, CH4, or C3H8. Here, an organic silane material such as TMS (trimethylsilane) (CH3)3SiH may be used as the carbon-containing gas.

[0033] The pressure inside the chamber 101 in the film forming step S2 is set to 1.5 Torr or less, and preferably 50 to 100 mTorr. The flow rates of the various process gases are determined in advance so as to optimize the quality of the silicon-containing film to be formed.

[0034] The film forming process S2 includes a first film forming step S21 and a second film forming step S22. In the first film forming step S21, a silicon-containing film is formed around the upper side of the plurality of protrusions 11 of the pattern. In the second film forming step S22, a silicon-containing film is formed on the upper parts of the plurality of protrusions 11 of the pattern.

[0035] In the film formation process S2, the second film formation step S22 may be performed after the first film formation step S21, or the first film formation step S21 may be performed after the second film formation step S22. In addition, in the film formation process S2, the first film formation step S21 and the second film formation step S22 may be performed alternately multiple times.

[0036] In the film forming step S2, 5 / 6 to 1 / 2 of the total thickness of the silicon-containing film to be formed is formed in the first film forming step S21, and the remaining of the total thickness is formed in the second film forming step S22. Here, the reason for making the film thickness in the first film forming step S21 5 / 6 to 1 / 2 of the total thickness and forming the remaining thickness in the second film forming step S22 is that the optimal distribution was derived from an experiment based on the optimal three-dimensional formation of the "adsorption control layer" in the film forming step S2. The most preferable distribution is about 1 / 2, which is the same for both the first film forming step S21 and the second film forming step S22, but even if the film thickness formed in the first film forming step S21 accounts for 5 / 6 of the total thickness, it is possible to approximately form the three-dimensional "adsorption control layer" as desired.

[0037] The first film-forming step S21 and the second film-forming step S22 will be described in more detail below.

[0038] In the first film-forming step S21, a silicon-containing film is formed under at least one of conditions of applying a higher bias power to the mounting table 102 and of having a higher refractive index (RI) than in the second film-forming step S22.

[0039] First, a case where the bias power is changed will be described. In the first film formation step S21, a higher bias power is applied to the mounting table 102 than in the second film formation step S22 to form a silicon-containing film. For example, in the first film formation step S21, a bias power of 200 W to 1000 W is applied to the mounting table 102. In the second film formation step S22, a bias power of 0 W to 200 W is applied to the mounting table 102.

[0040] FIG. 4 is a diagram for explaining the film formation results by the first film formation step S21 and the second film formation step S22 according to the embodiment. FIG. 4 shows an enlarged view of the upper periphery of the protrusion 11 formed on the substrate W. FIG. 4 shows a case where the silicon-containing gas is SiH4 gas, the nitrogen-containing gas is NH3 gas, the second film formation step S22 is performed after the first film formation step S21, and a SiN film 20 is formed as a silicon-containing film. The first film formation step S21 and the second film formation step S22 have the same processing conditions, except for the bias power applied to the mounting table 102. The first film formation step S21 has a bias power of 300 to 600 [W]. The second film formation step S22 has a bias power of 0 to 100 [W]. 4, the SiN film 20a formed in the first film-forming step S21 and the SiN film 20b formed in the second film-forming step S22 are shown in a differentiated manner. In the first film-forming step S21, the SiN film 20a is selectively formed on the upper periphery of the protrusion 11. In the second film-forming step S22, the SiN film 20b is selectively formed on the upper portion of the protrusion 11 on which the SiN film 20a has been formed.

[0041] In the film forming process S2, the SiN film 20a and the SiN film 20b are formed in a first film forming step S21 and a second film forming step S22, so that the shape of the SiN film 20 made of the SiN film 20a and the SiN film 20b can be controlled. The SiN film 20 protrudes laterally (toward the adjacent recess 12) around the upper portion of the protrusion 11, and has an overhanging shape. In FIG. 4, the thickness (Top Thickness) of the SiN film 20 formed on the upper surface of the protrusion 11 is shown as thickness TH. Also, the most laterally protruding portion of the SiN film 20 is shown as overhang point 21. Also, the depth (Overhang Depth) from the upper surface of the SiN film 20 to the position of the overhang point 21 is shown as OD. For example, by forming the SiN film 20 by the first film formation step S21 and the second film formation step S22, the depth OD of the overhang point 21 can be deepened, and the position of the overhang point 21 of the SiN film 20 can be lowered. As a result, for example, the position of the overhang point 21 of the SiN film 20 can be lowered below the position of the upper surface of the protrusion 11. Here, the significance (advantage) of deepening the OD will be explained. Generally, in PECVD without the two-stage film formation step proposed in this application, the OD cannot be formed deep unless a strong RF bias is applied by the high frequency power source connected to the mounting table 102. However, even if the OD can be formed deep when the RF bias is applied strongly, erosion (damage) occurs in the SiN film 20 due to the side effect of sputtering, or the SiN film 20 is formed deep into the recess of the base pattern, so that the optimal shape as the desired "adsorption control layer" cannot be obtained. Therefore, the ability to form a deep OD is one of the indicators of the performance required for the "adsorption control layer".

[0042] Here, as a comparative example, a case where the film is formed only by the first film forming step S21 in the film forming process S2 will be described. FIG. 5 is a diagram for explaining the film formation result of the comparative example. FIG. 5 shows the result of forming the SiN film 20a by the first film forming step S21 until the thickness TH is the same as that of the SiN film 20 in FIG. 4. The most lateral protruding part of the SiN film 20a is shown as the overhang point 22. In the first film forming step S21, the SiN film 20a is formed around the upper side of the protrusion 11, so that the depth OD of the overhang point 22 from the upper surface of the SiN film 20a becomes shallow. As a result, the position of the overhang point 22 of the SiN film 20a is higher than that of the overhang point 21 of the SiN film 20 in FIG. 4. Here, the depth of OD affects the margin (dimensional margin) of the processed shape after the implementation of the CMP or the like in the subsequent process, so it is desirable to make it as deep as the same position as TH.

[0043] The process conditions such as the type, flow rate, and bias power of the process gas in the first film formation step S21 and the second film formation step S22 are as follows.

[0044] <First Film Forming Step S21> ·Processing gas SiH4 gas: 3 to 60 [sccm] (preferably 7 to 20 [sccm]) NH3 gas: 4 to 100 [sccm] (preferably 9 to 40 [sccm]) Dilution inert gas: Ar gas: 50 to 1000 [sccm] (preferably 50 to 300 [sccm]) Microwave power (860MHz): 1500-10000[W] (preferably 2500-5000W Bias power (400KHz): 200-1000[W] (preferably 300-600[W]) <Second Film Forming Step S22> ·Processing gas SiH4 gas: 3 to 60 [sccm] (preferably 7 to 20 [sccm]) NH3 gas: 4 to 100 [sccm] (preferably 9 to 40 [sccm]) Dilution inert gas: Ar gas: 50 to 1000 [sccm] (preferably 50 to 300 [sccm]) Microwave power (860MHz): 1500-10000[W] (preferably 2500-5000W Bias power (400KHz): 0-200[W] (preferably 0-100[W])

[0045] FIG. 6 is a diagram showing an example of the film formation result. Comparative Example 1 shows a case where a SiN film is formed to a thickness of 150 [Å] only by the second film formation step S22. Comparative Example 2 shows a case where a SiN film is formed to a thickness of 150 [Å] only by the first film formation step S21. Example 1 shows a case where a SiN film is formed to a thickness of 125 [Å] in the first film formation step S21, and then a SiN film is formed to a thickness of 25 [Å] in the second film formation step S22, resulting in a SiN film having a total thickness of 150 [Å]. Example 2 shows a case where a SiN film is formed to a thickness of 75 [Å] in the first film formation step S21, and then a SiN film is formed to a thickness of 75 [Å] in the second film formation step S22, resulting in a SiN film having a total thickness of 150 [Å]. "Overhang position OD (nm)" shows the depth from the top surface of each SiN film to the position of the overhang point. 6, the "Overhang position OD (nm)" is 10 [nm] for Comparative Example 1, 13 [nm] for Comparative Example 2, and 15 [nm] for Examples 1 and 2. Thus, the depth to the overhang point is greater in Examples 1 and 2 than in Comparative Example 1 and Comparative Example 2.

[0046] In Fig. 6, the SiN film is formed by performing the second film formation step S22 after the first film formation step S21. However, even if the second film formation step S22 is performed first and then the first film formation step S21 is performed, the depth to the overhang point position is increased in the same manner. That is, the first film formation step S21 may be performed after the second film formation step S22. Also, the first film formation step S21 and the second film formation step S22 may be performed alternately multiple times.

[0047] Next, a case where the refractive index (RI) of the silicon-containing film to be formed is changed will be described. In the first film formation step S21 and the second film formation step S22, the refractive index of the silicon-containing film is controlled by the flow rate ratio of the silicon-containing gas to the nitrogen-containing gas. For example, in the first film formation step S21, the flow rate ratio (A / B) of the silicon-containing gas: A to the nitrogen-containing gas: B is set to 0.5 to 0.8. In the second film formation step S22, the flow rate ratio (A / B) of the silicon-containing gas: A to the nitrogen-containing gas: B is set to 0.8 to 1.0.

[0048] The bias power applied to the mounting table 102 is the same in the first film formation step S21 and the second film formation step S22. For example, in the first film formation step S21 and the second film formation step S22, a bias power of 0 W to 1000 W is applied to the mounting table 102. The bias power applied to the mounting table 102 may be changed. For example, as described above, in the first film formation step S21, a higher bias power may be applied to the mounting table 102 than in the second film formation step S22 to form a silicon-containing film.

[0049] By forming a silicon-containing film having a low refractive index in the second film formation step S22, the insulating properties (leak characteristics) of the silicon-containing film can be improved. However, the silicon-containing film having a low refractive index tends to have a shallower depth to the overhang point than the silicon-containing film having a high refractive index.

[0050] Therefore, in the film forming process S2, the flow rate ratio of the silicon-containing gas and the nitrogen-containing gas is changed between the first film forming step S21 and the second film forming step S22, and the silicon-containing film is formed under conditions in which the refractive index is higher in the first film forming step S21 than in the second film forming step S22. For example, the silicon-containing gas is SiH4 gas, the nitrogen-containing gas is NH3 gas, and after the SiN film 20a having a refractive index of 1.95 to 2.05 is formed in the first film forming step S21, the SiN film 20b having a refractive index of 2.05 or more is formed in the second film forming step S22. This allows the SiN film 20 consisting of the SiN film 20a and the SiN film 20b to be formed as shown in FIG. 4 above.

[0051] The process conditions such as the type, flow rate, and bias power of the process gas in the first film formation step S21 and the second film formation step S22 are as follows.

[0052] <First Film Forming Step S21> ·Processing gas SiH4 gas: 3 to 60 [sccm] (preferably 7 to 20 [sccm]) NH3 gas: 4 to 100 [sccm] (preferably 9 to 40 [sccm]) Dilution inert gas: Ar gas: 50 to 1000 [sccm] (preferably 50 to 300 [sccm]) Microwave power (860MHz): 1500-10000[W] (preferably 2500-5000W) Bias power (400kHz): 200-1000[W] (preferably 300-600[W]) <Second Film Forming Step S22> ·Processing gas SiH4 gas: 3 to 60 [sccm] (preferably 7 to 20 [sccm], same as the first film formation step S21) NH3 gas: 4 to 100 [sccm] (preferably 9 to 40 [sccm], same as the first film formation step S21) Dilution inert gas: Ar gas: 50 to 1000 [sccm] (preferably 50 to 300 [sccm]) Bias power (400kHz): 200-1000[W] (preferably 300-600[W])

[0053] In the second film formation step S22, the supply amount of NH3 gas is increased compared to the first film formation step S21, and the flow rate ratio of SiH4 gas and NH3 gas is changed to increase the refractive index of the formed SiN film. As a result, the depth to the overhang point of the SiN film formed on the convex portion is increased.

[0054] The substrate W on which the silicon-containing film has been formed by the film forming method according to the embodiment in the plasma processing apparatus 100 is unloaded from the plasma processing apparatus 100, and subsequent steps such as ALD film formation are performed.

[0055] FIG. 7 is a diagram for explaining an example of a subsequent process performed on the substrate W. FIG. 7(A) shows the substrate W on which the SiN film 20 is formed as a silicon-containing film on the protrusions 11 by the film forming method according to the embodiment. The substrate W on which the SiN film 20 is formed is polished from the upper surface side by, for example, CMP (Chemical Mechanical Polishing) or the like. For example, the substrate W is polished to a position of a dotted line below the upper surface of the protrusions 11 so that the upper surface of the protrusions 11 is exposed. FIG. 7(B) shows the polished substrate W. Since the SiN film 20 has a deep overhang point, it remains thick on the side surface of the protrusions 11, and the opening of the recess 12 can be narrowed. In the subsequent process, a film is formed by ALD on the substrate W with the opening of the recess 12 narrowed in this manner.

[0056] Conventionally, the ALD process has a problem of large processing capacity (throughput) in the process time of film formation, and in order to shorten the process time of film formation, the concentration of the ALD precursor is increased. In theory, there is no problem if the ALD reaction is ideal, the ALD precursor only chemisorbs to the surface of the material, and the excess ALD precursor does not physisorb to the adsorbed surface after the saturated chemisorption. However, in many cases, a part of the ALD precursor that penetrates deep inside the base recess is physisorbed. As a result, when ALD is performed on the substrate W without the SiN film 20, the high concentration ALD precursor penetrates from the opening side of the recess 12, so that the film thickness is thick at the top of the recess 12 and thin at the bottom, resulting in overhangs and poor step coverage. Therefore, it is possible to reduce the concentration of the ALD precursor, but this would increase the process time of film formation and reduce productivity.

[0057] On the other hand, when an ALD process is performed on the substrate W of FIG. 7(B), even if a high concentration of ALD precursor is generated, the amount of ALD precursor penetrating into the recess 12 is reduced by narrowing the opening at the top of the recess 12, and the effective density of the ALD precursor penetrating into the recess 12 is lowered, so that a film can be formed with good step coverage.

[0058] After the ALD process, the substrate W is polished from the upper surface side by, for example, CMP or the like to remove the SiN film 20.

[0059] In the embodiment, the silicon-containing film is formed using a microwave plasma type plasma processing apparatus 100 that generates plasma by microwaves. However, it is also possible to form the silicon-containing film using a CCP (Capacitively Coupled Plasma) type plasma processing apparatus that uses parallel plates. However, the CCP type plasma processing apparatus has high ion energy of plasma, and the silicon-containing film is formed deep into the recess 12.

[0060] FIG. 8 is a diagram for explaining film formation by microwave plasma and CCP. FIG. 8 shows the patterns of plasma ion energy in the recess 12 when the SiN film 20 is formed on the substrate W by microwave plasma and CCP. FIG. 8 also shows the shapes of the SiN film 20 formed on the sidewall of the recess 12 by microwave plasma and CCP. CCP has high plasma ion energy, so the SiN film 20 is formed deep into the recess 12. On the other hand, microwave plasma can reduce the plasma ion energy compared to CCP, and the range in which the SiN film 20 is formed can be made shallow. This allows the film to be formed from a shallow position in the recess 12 in the subsequent process. Also, for example, when the substrate W is polished by CMP or the like to remove the SiN film 20, the polishing depth can be reduced.

[0061] In the above embodiment, the case where a SiN film is formed as the silicon-containing film has been described as an example, but the silicon-containing film to be formed is not limited to a SiN film. For example, a carbon-containing gas such as C2H6 gas or TMS(CH3)3SiH may be added to the processing gas to form a SiCN film as the silicon-containing film. Also, a diborane (B2H6) gas may be added to the processing gas to form a SiBN film as the silicon-containing film. For example, by adding a small amount of carbon-containing gas (for example, C2H6 gas at about 0.1 to 10 [sccm]), it is possible to form a SiCN film with better chemical resistance (HF wet etching resistance) without changing the film shape characteristics in the film forming process S2 (film number 20). Similarly, adding a small amount of diborane (B2H6) gas (e.g., approximately 0.1 to 15 [sccm]) can also improve the chemical resistance to LAL buffered hydrofluoric acid (a mixed solution of NHF and HF) without changing the film shape characteristics (film number 20).

[0062] As described above, the film forming method according to the embodiment includes a placing step S1 and a film forming step S2. In the placing step S1, the substrate W on which a pattern having a plurality of projections and recesses is formed is placed on the mounting table 102 arranged in the chamber 101. In the film forming step S2, a bias power is applied to the mounting table 102, and a process gas containing a silicon-containing gas and a nitrogen-containing gas is supplied into the chamber 101 while a microwave is introduced into the chamber 101 to generate plasma, and a silicon-containing film is selectively formed on the plurality of projections 11 of the pattern. The film forming step S2 includes a first film forming step S21 and a second film forming step S22. In the first film forming step S21, a silicon-containing film is formed on the upper periphery of the plurality of projections 11. In the second film forming step S22, a silicon-containing film is formed on the upper part of the plurality of projections 11. As a result, the film forming method according to the embodiment can control the shape of the silicon-containing film to be formed to a shape that allows a film with good uniformity to be obtained in the recess by ALD film formation.

[0063] In addition, the first film formation step S21 forms the silicon-containing film under at least one of the conditions of applying a higher bias power to the mounting table 102 and forming a silicon-containing film with a higher refractive index than in the second film formation step S22. As a result, the film formation method according to the embodiment can deepen the position of the overhang point 21 of the formed silicon-containing film.

[0064] In addition, in the first film formation step S21, a bias power of 200 W to 600 W is applied to the mounting table 102. In the second film formation step S22, a bias power of 0 W to 200 W is applied to the mounting table 102. Thus, in the film formation method according to the embodiment, by changing the bias power in this manner in the first film formation step S21 and the second film formation step S22, the position of the overhang point 21 of the silicon-containing film to be formed can be made deeper.

[0065] In addition, the first film formation step S21 forms a silicon-containing film having a refractive index of 1.95 to 2.05. The second film formation step S22 forms a silicon-containing film having a refractive index of 2.05 or more. In this way, the film formation method according to the embodiment can deepen the position of the overhang point 21 of the silicon-containing film by changing the refractive index of the silicon-containing film thus formed in the first film formation step S21 and the second film formation step S22.

[0066] In the film formation step S2, 5 / 6 to 1 / 2 of the total thickness of the silicon-containing film to be formed is formed in the first film formation step S21, and the remaining of the total thickness is formed in the second film formation step S22. As a result, the film formation method according to the embodiment can form the shape of the silicon-containing film to be formed into a shape that allows a film with good uniformity to be obtained in the recess by ALD film formation.

[0067] Although the embodiments have been described above, the disclosed embodiments should be considered to be illustrative and not restrictive in all respects. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the claims.

[0068] For example, in the above embodiment, the substrate W is a semiconductor wafer, but the present invention is not limited thereto. In addition, the present invention is not limited thereto, but the present invention is also useful for a substrate having a pattern having projections and recesses in the horizontal direction in addition to the vertical direction, such as a 3D structure.

[0069] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be construed as limiting. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0070] 11 Convex 12 Recess 100 Plasma treatment device 101 Chamber 102 Placement table 103 Gas supply mechanism 105 Microwave Plasma Source 106 Control section 122 High frequency power supply 123 Gas introduction nozzle 124 Gas supply pipe 125 Gas Supply Section 130 Microwave output section 140 Antenna unit W substrate

Claims

1. a placing step of placing a substrate on a placing table disposed in a chamber, the substrate having a pattern having a plurality of projections and recesses formed thereon; a film formation process in which a bias power is applied to the mounting table, a process gas containing a silicon-containing gas and a nitrogen-containing gas is supplied into the chamber, and microwaves are introduced into the chamber to generate plasma, thereby selectively forming a silicon-containing film on the multiple convex portions of the pattern; having the film forming step includes a first film forming step of forming a silicon-containing film on upper peripheries of the plurality of convex portions, and a second film forming step of forming a silicon-containing film on upper portions of the plurality of convex portions, In the first film formation step, a silicon-containing film is formed under at least one of the conditions of applying a higher bias power to the mounting table and of forming a higher refractive index than in the second film formation step. Film formation method.

2. the first film forming step applies a bias power of 200 W to 1000 W to the mounting table; The second film forming step applies a bias power of 0 to 200 W to the mounting table. The film forming method according to claim 1 .

3. The first film-forming step forms a silicon-containing film having a refractive index of 1.95 to 2.05; The second film-forming step forms a silicon-containing film having a refractive index of 2.05 or more. The film forming method according to claim 1 .

4. In the first film forming step and the second film forming step, the refractive index of the silicon-containing film is controlled by a flow rate ratio of the silicon-containing gas to the nitrogen-containing gas. The film forming method according to claim 1 or 3.

5. the first film forming step is performed with a flow rate ratio of the silicon-containing gas to the nitrogen-containing gas being 0.5 to 0.8; In the second film forming step, a flow rate ratio of the silicon-containing gas to the nitrogen-containing gas is set to 0.8 to 1.

00.

5. The film forming method according to claim 1, 3 or 4.

6. The first film forming step and the second film forming step apply the same bias power to the mounting table.

6. The film forming method according to claim 1, 3, 4 or 5.

7. The silicon-containing gas is SiH ４ , Si 2 H 6 , SiH 2 C 4 Either The nitrogen-containing gas is NH ３ , N ２ Either The film forming method according to any one of claims 1 to 6.

8. The process gas further comprises a carbon-containing gas. The film forming method according to any one of claims 1 to 7.

9. The carbon-containing gas is ２ H ６ , C.H. ４ , C 3 H ８ Either The film forming method according to claim 8.

10. In the film forming process, 5 / 6 to 1 / 2 of the total thickness of the silicon-containing film to be formed is formed in the first film forming step, and the remaining of the total thickness is formed in the second film forming step. The film forming method according to any one of claims 1 to 9.

11. The film forming step forms any one of a SiN film, a SiCN film, and a SiBN film as the silicon-containing film. The film forming method according to any one of claims 1 to 10.

12. a mounting table disposed in the chamber and on which a substrate having a pattern having a plurality of projections and recesses is placed; a power supply that applies a bias power to the mounting table; a gas supply unit for supplying a process gas containing a silicon-containing gas and a nitrogen-containing gas into the chamber; a plasma source that generates and radiates microwaves into the chamber; a control unit that controls to perform a film formation process including: applying a bias power from the power source to the mounting table; generating plasma by introducing microwaves from the plasma source into the chamber while supplying a process gas containing a silicon-containing gas and a nitrogen-containing gas from the gas supply unit into the chamber; and forming a silicon-containing film on upper peripheries of a plurality of convex portions of the pattern and a second film formation step of forming a silicon-containing film on upper parts of the plurality of convex portions, so as to selectively form a silicon-containing film on the plurality of convex portions, The control unit controls the first film-forming step to apply a higher bias power to the mounting table and to form a silicon-containing film under at least one of conditions having a higher refractive index than those in the second film-forming step. Film deposition equipment.

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