Semiconductor device manufacturing method and substrate processing apparatus

Abstract

To embed a film in a recess without generating a void even when there is irregularity on a side surface in the recess and the film is embedded in the recess in such a shape that the void is easily generated.SOLUTION: A manufacturing method of a semiconductor device comprises the steps of: supplying silicon-containing gas to a substrate in which a recess is provided in the front surface and accumulating a silicon film in the recess; supplying first etching gas having a first etching profile with different etching amounts in an upper portion and a lower portion in the depth direction of the recess to the substrate and etching the silicon film in the recess; supplying second etching gas having a second etching profile different from the first etching profile of the first etching gas to the substrate and etching the silicon film in the recess; and newly accumulating the silicon film on the silicon film etched with the second etching gas.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a semiconductor device and a substrate processing apparatus. [Background technology]

[0002] Conventionally, a method for manufacturing a semiconductor device has been known in which the steps of supplying a silicon-containing film-forming gas to a workpiece having a recess formed on its surface to form a silicon film in the recess, supplying a process gas containing a halogen gas for etching the silicon film and a roughness-suppressing gas for suppressing roughness of the surface of the silicon film after etching with the halogen gas to the workpiece, and further providing thermal energy to the process gas to activate it and perform etching, thereby widening the opening width of the recess, are repeated to fill the recess with a silicon film (see, for example, Patent Document 1). This filling method is called a Deposition Etch Deposition (DED) process, since deposition and etching are repeated. [Prior art documents] [Patent documents]

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

[0004] To provide a semiconductor device manufacturing method and a substrate processing apparatus capable of embedding a film in a recess without generating voids, even when the recess has an uneven side surface and a shape in which voids are likely to occur. [Means for solving the problem]

[0005] In order to achieve the above object, a method for manufacturing a semiconductor device according to an embodiment of the present disclosure includes the steps of: supplying a silicon-containing gas to a substrate having a recess on a surface thereof, and depositing a silicon film in the recess; supplying a first etching gas having a first etching profile in which an etching amount differs between an upper portion and a lower portion in a depth direction of the recess to the substrate, thereby etching the silicon film in the recess; supplying a second etching gas having a second etching profile different from the first etching profile of the first etching gas to the substrate, and etching the silicon film in the recess; and depositing a new silicon film on the silicon film etched with the second etching gas. death, the first etching profile of the first etching gas is such that an etching amount of the upper portion of the recess in a depth direction is greater than an etching amount of the lower portion of the recess; The second etching profile of the second etching gas has a smaller ratio of the etching amount of the upper portion to the etching amount of the lower portion than that of the first etching profile, or the etching amount of the upper portion and the etching amount of the lower portion are equal to each other. . Effect of the Invention

[0006] According to the present disclosure, a film can be embedded in a recess without generating voids. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 illustrates a substrate processing apparatus according to an embodiment of the present disclosure. [Diagram 2] 3A to 3C are diagrams showing examples of shapes of recesses formed on the surface of a wafer W. [Diagram 3] FIG. 1 illustrates an example of a typical conventional DED process. [Figure 4] FIG. 1 illustrates the DED process when the recess has flat sides. [Diagram 5] 13A to 13C are diagrams showing an example of a DED process when the side surface of a recess is not flat. [Figure 6] 1A to 1C are diagrams illustrating an example of a manufacturing method of a semiconductor device according to an embodiment of the present disclosure. [Figure 7]FIG. 4 is a diagram for explaining etching profiles in the depth direction of a first etching gas and a second etching gas. [Figure 8] FIG. 2 is a process flow diagram showing a method for manufacturing a semiconductor device according to the first embodiment. [Figure 9] FIG. 11 is a process flow diagram showing an example of a method for manufacturing a semiconductor device according to a second embodiment. [Figure 10] FIG. 11 is a diagram showing a process flow of a method for manufacturing a semiconductor device according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0009] FIG. 1 is a diagram showing a substrate processing apparatus according to an embodiment of the present disclosure. In this embodiment, an example in which the substrate processing apparatus is configured as a vertical heat processing apparatus will be described. Note that the substrate processing apparatus according to the present disclosure is not limited to a vertical heat processing apparatus, and can be applied to various substrate processing apparatuses capable of alternately performing film formation and etching. Applicable substrate processing apparatuses include single-wafer substrate processing apparatuses and semi-batch substrate processing apparatuses. In this embodiment, an example in which the substrate processing apparatus is configured as a vertical heat processing apparatus will be described.

[0010] The vertical thermal processing apparatus performs a DED process to form logic elements of a semiconductor device on a substrate, a wafer W. In other words, a film formation process and an etching process are performed on the wafer W. The film formation process is a process using thermal CVD (Chemical Vapor Deposition), and the etching process is a reactive gas etching process performed by supplying thermal energy to an etching gas.

[0011] The logic elements to be manufactured include, in addition to conventionally manufactured logic elements, logic elements using FinFETs, which are the next generation transistors after MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), for example.

[0012] The vertical heat treatment apparatus includes a reaction tube 11, which is a substantially cylindrical vacuum vessel with its longitudinal direction oriented vertically. The reaction tube 11 has a double-tube structure consisting of an inner tube 12 and an outer tube 13 with a ceiling that covers the inner tube 12 and is formed to have a certain distance from the inner tube 12. The inner tube 12 and the outer tube 13 are made of a heat-resistant material, for example, quartz. The reaction tube 11 may be called a processing chamber because it forms a closed space in which substrates are processed.

[0013] A cylindrical manifold 14 made of stainless steel (SUS) is disposed below the outer tube 13. The manifold 14 is airtightly connected to the lower end of the outer tube 13. The inner tube 12 protrudes from the inner wall of the manifold 14 and is supported by a support ring 15 formed integrally with the manifold 14.

[0014] A lid 16 is disposed below the manifold 14, and the lid 16 can be raised and lowered between an upper position and a lower position by the boat elevator 10. FIG. 1 shows the lid 16 in the upper position, and in this upper position, the lid 16 closes an opening 17 of the reaction tube 11 below the manifold 14, making the inside of the reaction tube 11 airtight. A wafer boat 3 made of, for example, quartz is placed on the lid 16. The wafer boat 3 is configured to hold a number of wafers W to be processed as substrates horizontally at a predetermined interval in the vertical direction. A heat insulator 18 is provided around the reaction tube 11 so as to surround the reaction tube 11, and a heater 19 made of, for example, a resistance heating element, which is a heating unit, is provided on the inner wall surface of the heat insulator 18, which can heat the inside of the reaction tube 11.

[0015] In the manifold 14, a process gas introduction pipe 21 and a purge gas introduction pipe 31 are inserted below the support ring 15, and the downstream ends of the gas introduction pipes 21 and 31 are arranged so as to supply gas to the wafer W in the inner pipe 12. For example, the upstream side of the process gas introduction pipe 21 branches to form branch paths 22A to 22E, and the upstream ends of the branch paths 22A to 22E are connected to a diisopropylaminosilane (DIPAS) gas supply source 23A, a disilane (Si2H6) gas supply source 23B, a monoaminosilane (SiH4) gas supply source 23C, a chlorine (Cl2) gas supply source 23D, and a nitrogen (N2) gas supply source 23E. Gas supply mechanisms 24A to 24E are respectively provided in the branch paths 22A to 22E. The gas supply mechanisms 24A to 24E each include a valve and a mass flow controller, and are configured to be able to control the flow rate of the process gas supplied to the process gas introduction pipe 21 from the gas supply sources 23A to 23E, respectively.

[0016] The DIPAS gas is a seed layer formation gas for forming a first seed layer on the surface of a silicon oxide film formed on the surface of the wafer W, and the gas supply source 23A and the gas supply mechanism 24A constitute a DIPAS gas supply unit.

[0017] The Si2H6 gas is a seed layer forming gas for forming a second seed layer on the surface of the first seed layer, and the gas supply source 23B and the gas supply mechanism 24B constitute a Si2H6 (disilane) gas supply unit.

[0018] The DIPAS gas supply unit and the disilane gas supply unit are gas supply units for forming a seed layer, and therefore may be called a seed layer forming gas supply unit.

[0019] In this embodiment, an example is described in which two types of gases for forming a seed layer are used, but any one of the gases for forming a seed layer may be used. In addition, when forming a film on a wafer W on which a seed layer has already been formed, the seed layer forming gas supply unit may not be required. Furthermore, even when the seed layer forming gas supply unit is used, gases other than DIPAS gas and Si2H6 gas may be used. In this way, the DIPAS gas supply unit and disilane gas supply unit, which are given as examples, and the seed layer forming gas supply unit may be provided as necessary.

[0020] The SiH4 gas is a film-forming gas for forming a silicon (Si) film on the wafer W, and the gas supply source 23C and the gas supply mechanism 24C constitute a silicon-containing gas supply unit. Since the silicon-containing gas is a gas used in film formation, the silicon-containing gas supply unit may be called a film-forming gas supply unit.

[0021] Cl2 gas is an etching gas for etching the Si film, and the gas supply source 23D and the gas supply mechanism 24D constitute a chlorine gas supply unit. N2 gas is a dilution gas for changing the etching profile of the etching gas in the depth direction of the recess 142, and the gas supply source 23E and the gas supply mechanism 24E constitute a nitrogen gas supply unit. Since chlorine gas and nitrogen gas are supplied simultaneously as etching gases, the chlorine gas supply unit and the nitrogen gas supply unit may be collectively called an etching gas supply unit.

[0022] The upstream side of the purge gas introduction pipe 31 is connected to a supply source 32 of nitrogen (N2) gas, which is a purge gas. A gas supply mechanism 33 is provided in the purge gas introduction pipe 31. The gas supply mechanism 33 is configured similarly to the gas supply mechanisms 24A to 24E, and controls the flow rate of the purge gas to the downstream side of the introduction pipe 31.

[0023] Further, the manifold 14 has an exhaust port 25 opening on a side surface above the support ring 15, and exhaust gas generated in the inner tube 12 is exhausted to the exhaust port 25 through a space formed between the inner tube 12 and the outer tube 13. An exhaust pipe 26 is airtightly connected to the exhaust port 25. A valve 27 and a vacuum pump 28 are installed in the exhaust pipe 26 from its upstream side in this order. By adjusting the opening of the valve 27, the pressure inside the reaction tube 11 is controlled to a desired pressure.

[0024] The vertical heat treatment apparatus is provided with a control unit 30 configured by a computer, and the control unit 30 is provided with a program. This program is structured with a group of steps so that a series of processing operations described below can be performed on the wafer W by outputting control signals to each part of the vertical heat treatment apparatus 1 to control the operation of each part. Specifically, control signals are output so that the boat elevator 10 raises and lowers the lid 16, the output of the heater 19 (i.e., the temperature of the wafer W), the opening of the valve 27, the supply flow rate of each gas into the reaction tube 11 by the gas supply mechanisms 24A to 24C and 33, and the like are controlled. This program is stored in the control unit 30 in a state of being stored in a storage medium such as a hard disk, a flexible disk, a compact disk, a magnet optical disk (MO), or a memory card.

[0025] Fig. 2 is a diagram showing an example of the shape of a recess formed on the surface of a wafer W. As shown in Fig. 2, a silicon (Si) layer 41 is provided on the surface of the wafer W. The surface of the Si layer 41 is oxidized to form a silicon oxide film 43. A recess 42 having a depth D and an opening width S is also formed. The recess 42 is formed as, for example, a trench or a through hole, but any shape is acceptable as long as it is a recessed shape.

[0026] 2, the aspect ratio of the recess 42 is D / S. The aspect ratio of the recess is, for example, 2 or more.

[0027] First, a general method for filling a silicon film into a recess 42 as shown in FIG. 2 by applying a DED process will be described.

[0028] FIG. 3 is a diagram showing an example of a typical conventional DED process.

[0029] 3(a) is a diagram showing a seed layer formation process for forming a seed layer 44 on the surface of a wafer W having a recess 42 on the surface. In the seed layer formation process, a thin silicon film is formed as the seed layer 44 on the surface of a silicon oxide film 43 on the surface. To form the seed layer 44, for example, Si2H6 is used as a film formation gas.

[0030] 3(b) is a diagram showing the first film formation process. In the first film formation process, for example, SiH4 gas is used as a film formation gas, and a silicon film 45 is formed on the surface of the wafer W and deposited in the recess 42.

[0031] 3(c) is a diagram showing an example of an etching process. In the etching process, the formed silicon film 45 is etched to widen the opening width so that the upper end is not blocked. Then, a V-shaped cross section is formed in the silicon film 45.

[0032] 3(d) shows the second film formation process. In the second film formation process, a new silicon film 45a is deposited on the V-shaped silicon film 45, and the entire recess 42 is filled with the silicon films 45, 45a.

[0033] Such a filling method is a DED process, which can fill the recess 42 with silicon films 45, 45a without creating voids, even in the recess 42 with a high aspect ratio.

[0034] FIG. 4 illustrates the DED process when the recess 42 has flat sides.

[0035] Fig. 4(a) is a diagram showing an example of the shape of the recess 42. As shown in Fig. 4(a), the recess 42 has a flat side surface, and a seed layer 44 is formed on the surface.

[0036] 4(b) is a diagram showing an example of the first film forming step. A silicon-containing gas is supplied to deposit a silicon film 45 in the recess 42. This narrows the opening of the recess 42.

[0037] 4(c) is a diagram showing an example of an etching process. In the etching process, the cross section of the silicon film 45 deposited in the recess 42 is made V-shaped. This widens the opening.

[0038] 4(d) is a diagram showing an example of the second film forming step, in which the opening becomes wider and the opening of the silicon film 45 is filled with the silicon film 45a without forming voids, and the entire recess 42 can be filled with the silicon films 45, 45a without forming voids.

[0039] FIG. 5 is a diagram showing an example of a DED process in which the side surface of a recess 42a has a protrusion 42b and is not flat.

[0040] Fig. 5(a) is a diagram showing an example of the shape of the recess 42a. As shown in Fig. 5(a), the recess 42a has a protrusion 42b on its side surface, making the side surface uneven.

[0041] 5(b) is a diagram showing an example of the film formation process. In the film formation process, a silicon film is basically formed conformally, so that the silicon film 45 is formed in a shape that follows the shape of the recessed portion 42a and has a portion of the protruding portion 42b protruding inward.

[0042] 5(c) is a diagram showing an example of an etching step. In the etching step, etching is performed to form a V shape, so that the upper part is widely opened, but the other parts are not etched very much.

[0043] 5(d) is a diagram showing an example of the second film-forming process. In the second film-forming process, since the opening of the protrusion 42b is narrow, the silicon-containing gas does not reach the depression 42c below the recess 42a, and the depression 42c, which is in a depressed shape due to the presence of the protrusion 42b, is not filled, and a void remains.

[0044] That is, even if the DED process shown in FIGS. 3 and 4 is performed, the recess 42a having unevenness cannot be filled with the silicon films 45 and 45a.

[0045] The convex portion 42b may be formed due to processing accuracy issues, or may be formed in such a shape. In any case, the concave portion 42a having unevenness exists in the actual process, and it is difficult to fill such a concave portion 42a.

[0046] Therefore, the present disclosure proposes a method for filling the recess 42a with a silicon film without generating voids, even in the recess 42a having unevenness.

[0047] 6 is a diagram showing an example of a method for manufacturing a semiconductor device according to an embodiment of the present disclosure. The method for manufacturing a semiconductor device according to the present embodiment will be described with reference to FIGS.

[0048] First, the wafers W described in FIG. 2 are transferred to the wafer boat 3 by a transfer mechanism (not shown) and held thereon. Then, the wafer boat 3 is placed on the lid 16 located at the lowered position. Then, the lid 16 is raised to the raised position, the wafer boat 3 is carried into the reaction tube 11, the opening 17 of the reaction tube 11 is closed by the lid 16, and the reaction tube 11 is made airtight. Next, a purge gas is supplied into the reaction tube 11, and the reaction tube 11 is evacuated to a vacuum atmosphere of a predetermined pressure, and the wafers W are heated to a predetermined temperature by the heater 19. The temperature at this time is set to a predetermined film formation temperature suitable for depositing a silicon film on the wafers W. The temperature of the heater 19 may be controlled by the control unit 30.

[0049] For example, when SiH4 gas is used as the film forming gas, the temperature is set to a predetermined temperature within the range of 440 to 530° C., which is controllable with chlorine etching gas.

[0050] FIG. 6(a) illustrates an example of a seed layer formation step.

[0051] After the wafer W is heated, the supply of the purge gas is stopped, and the DIPAS gas is supplied into the reaction tube 11. The DIPAS gas is deposited on the surface of the silicon oxide film 43 of the wafer W, and a seed layer 44 is formed so as to cover the silicon oxide film 43 (see FIG. 6(a)).

[0052] Thereafter, the supply of DIPAS gas is stopped, a purge gas is supplied into the reaction tube 11, the DIPAS gas is purged from the reaction tube 11, and then Si2H6 gas is supplied into the reaction tube 11. This Si2H6 gas is deposited on the first seed layer, and a second seed layer is formed so as to cover the first seed layer. Thereafter, the supply of Si2H6 gas is stopped, a purge gas is supplied into the reaction tube 11, and the Si2H6 gas is purged from the reaction tube 11.

[0053] FIG. 6(b) is a diagram showing an example of the first film forming step.

[0054] After the seed layer formation process, the supply of the purge gas is stopped, and SiH4 gas is supplied into the reaction tube 11. As shown in FIG. 6(b), the SiH4 gas is deposited on the second seed layer, and a Si film 44 is formed on the entire surface of the wafer W so as to cover the second seed layer. Then, the deposition of the SiH4 gas continues, and the Si film 45 grows. That is, the thickness of the Si film 45 increases. Then, as shown in FIG. 6(b), for example, the supply of the SiH4 gas is stopped before the upper side of the recess 42a is blocked by the Si film 45. At this stage, the opposing distance of the silicon film 45 becomes very narrow in the portion of the protrusion 42b.

[0055] After the supply of the SiH4 gas is stopped, a purge gas is supplied into the reaction tube 11, and the SiH4 gas is purged from the reaction tube 11.

[0056] 6(c) is a diagram showing an example of the first etching process. In the first etching process, Cl2 gas is supplied from the gas supply source 23D to the process gas introduction pipe 21, and N2 gas is supplied from the gas supply source 23E to the process gas introduction pipe 21, and the gases are mixed in the process gas introduction pipe 21 and supplied to the wafer W in the reaction tube 11 (FIG. 1).

[0057] The Cl2 gas is an etching gas for the Si film 45, and generates active species such as Cl radicals by being heated in the reaction tube 11 and supplied with thermal energy. Since the active species has a relatively high reactivity with Si, it reacts with Si outside the recess 42 and on the upper side of the recess 42 before reaching the lower part of the recess 42 of the wafer W to generate SiCl4 (silicon tetrachloride), and the Si film 45 is etched. Therefore, etching is performed so that the decrease in the thickness of the Si film 45 on the upper side of the recess 42 is greater than the decrease in the thickness of the Si film 45 on the lower side of the recess 42, and the opening width on the upper side of the recess 42 is enlarged. In addition, 2 moles of Cl radicals are generated from 1 mole of Cl2. In other words, since a relatively large number of active species are generated, the enlargement of the opening width can proceed at a relatively high speed.

[0058] At this time, the amount of nitrogen gas supplied is reduced and etching is performed so as to widen the V-shaped opening. In other words, etching is performed in a state close to the conventional V-shape formation.

[0059] The flow rate ratio of chlorine gas to nitrogen gas may be set so that the flow rate of chlorine gas is greater than the flow rate of nitrogen gas. For example, the flow rate ratio of chlorine gas to nitrogen gas may be set to 10:1-9, 10:4-8, or 10:6-7.

[0060] For example, when the flow rate of chlorine gas is 1 slm, the flow rate of nitrogen gas may be set to 0.65 slm. Etching can be performed without significantly changing the etching profile of the chlorine gas in the depth direction, in which the upper stage is more removed and the lower stage is less removed in the depth direction of the recess 42a, and the opening of the silicon film 45 in the recess 42a can be greatly expanded.

[0061] 6(d) is a diagram showing an example of the second etching step. In the second etching step, etching is performed with a narrow V shape and close to conformal. This makes it possible to widen the opening near the protrusion 45b in the recess 42a and the recess 42c below it. By widening the opening of the protrusion 42b and the recess 42c below it, in the next film formation, the silicon film 45 can reach the recess 42c and fill it without generating voids.

[0062] In the second etching process, Cl2 gas is supplied from the gas supply source 23D and N2 gas is supplied from the gas supply source 23E to the process gas introduction pipe 21, and the gases are mixed in the process gas introduction pipe 21 and supplied to the wafer W in the reaction tube 11 (FIG. 1).

[0063] However, the mixture ratio of chlorine gas and nitrogen gas is different from that of the first etching gas. The second etching gas is set so that the effect of increasing the opening width on the upper side of chlorine is weakened and etching is close to conformal. In other words, it is adjusted to have an etching profile in which the opening width is narrow and reaches the back even in the V-shape. Specifically, the flow rate ratio of nitrogen gas is increased. The flow rate ratio of chlorine gas and nitrogen gas may be set to, for example, chlorine gas:nitrogen gas is 1:2-10, 1:3-8, or 1:4-7. For example, when the flow rate of chlorine gas is 1 slm, the flow rate of nitrogen gas may be set to 5.75 slm.

[0064] By performing etching with the second etching gas having such a nearly conformal etching profile, the width of the opening below the protrusion 42b can be increased, allowing the silicon-containing gas to penetrate deep inside.

[0065] Thereafter, the supply of Cl2 gas and N2 gas into the reaction tube 11 is stopped, and the etching process is terminated.

[0066] Next, a purge gas is supplied to remove the mixed gas from the reaction tube 11. Then, after a predetermined time has elapsed, the supply of the purge gas is stopped.

[0067] 6(e) is a diagram showing an example of the second film formation process. In the second film formation process, a silicon-containing gas, for example, SiH4 gas, is supplied to deposit a new silicon film 45a on the etched silicon film 45. At this time, since the opening in the recess 42a is opened to the bottom with a sufficient opening width, the silicon film 45a can be embedded in the recess 42a without generating voids.

[0068] After filling all the recesses 42a, the temperature inside the reaction tube 11 is lowered. During the process, a constant film formation temperature is maintained, but after the process is completed, the temperature inside the reaction tube 11 is lowered in order to remove the wafer W. This causes the temperature of the wafer W to drop.

[0069] Subsequently, the lid 16 is lowered to unload the wafer boat 3 from the reaction tube 11, and then the wafers W are removed from the wafer boat 3 by a transfer mechanism (not shown), completing the processing of one batch of wafers W. Since the processing temperature can be kept constant during the processing, the embedding process can be completed in a short time.

[0070] As described above, according to the method for manufacturing a semiconductor device of this embodiment, by performing etching in two stages using two types of etching gases having different etching profiles in the depth direction, even if the recess 42a has an uneven surface, the opening width can be widened by etching, and the recess 42a can be filled without generating voids.

[0071] In addition, in FIG. 6, an example has been described in which the opening width at the top is first widened by using a first etching gas having a strong V-shaped etching profile, and then the opening width at the back is widened by using a second etching gas having a weak V-shaped etching profile that is nearly conformal. However, depending on the shape of the recess 42a, it may be better to reverse the order.

[0072] In such a case, a two-step etching may be used, in which a deep, narrow opening is formed in the first step, and the upper opening is widened in the second step. Furthermore, a two-step etching process may be performed by introducing an etching gas having a different etching profile or a dilution gas having a different etching profile.

[0073] In this manner, according to the method for manufacturing a semiconductor device of this embodiment, it is possible to determine the procedure for forming an opening depending on the uneven shape of recess 42a, and then perform two-stage etching accordingly, or even three-stage etching as necessary, to form an opening that does not generate voids.

[0074] Next, the etching characteristics of the first etching gas and the second etching gas will be described.

[0075] FIG. 7 is a diagram for explaining the etching profiles in the depth direction of the first etching gas and the second etching gas.

[0076] FIG. 7(a) is a diagram showing an example of the first etching gas in FIG. 6. The first etching gas is a gas with a low dilution amount of nitrogen gas. In FIG. 7(a), an example is given in which chlorine / nitrogen is 1 slm / 0.65 slm. In this way, the first etching gas may be configured by mixing so that the flow rate of chlorine is higher than the flow rate of nitrogen. This makes it possible to utilize the etching profile of chlorine gas and chlorine radicals that widens the upper opening width as it is, and form a strong V-shaped opening.

[0077] Figure 7(a) shows data when the first etching was performed under conditions of 375°C and 3 Torr. Specifically, if the thickness of the silicon film on the surface of the wafer between the recesses is called "top," the thickness on the side of the recesses is called "side," and the thickness on the bottom of the recesses is called "bottom," then side / top is 106.4% and bottom / top is 146.0%, resulting in an etching profile with a strong V-shape, a large opening at the top, and little etching at the bottom. Such an etching profile is effective in greatly widening the opening at the top of the recesses.

[0078] FIG. 7(b) is a diagram showing an example of the second etching gas in FIG. 6. The first etching gas is a gas with a low dilution amount of nitrogen gas. In FIG. 7(b), an example is given in which chlorine / nitrogen is 1 slm / 5.75 slm. In this way, the first etching gas may be mixed so that the flow rate of chlorine is higher than the flow rate of nitrogen. This makes it possible to utilize the etching profile in which the etching amount of the upper part of the chlorine gas and chlorine radicals is significantly larger than the etching amount of the lower part, widening the opening width, and forming a strong V-shaped opening.

[0079] Figure 7(b) shows data for the second etching performed under conditions of 375°C and 3 Torr, similar to Figure 7(a). Specifically, if the thickness of the silicon film on the surface of the wafer between the recesses is called "top", the thickness on the side of the recesses is called "side", and the thickness on the bottom of the recesses is called "bottom", then side / top is 104.1% and bottom / top is 125.1%, with a weak V-shape and little difference between the etching amounts at the top and bottom, resulting in an etching profile close to conformal. Such an etching profile is effective for widening the openings at the top and bottom of the recesses with the same level of etching amount.

[0080] In this way, by performing two-stage etching using two types of etching gases having different etching profiles in the depth direction of the recess, an opening with an appropriate opening width can be formed even if there are irregularities in the recess.

[0081] Next, various embodiments of a DED process using a first etch and a second etch are described.

[0082] 8 is a process flow diagram showing the method for manufacturing the semiconductor device according to the first embodiment. This is the simplest process similar to that described in FIG.

[0083] In step S10, a first film formation process is performed. This corresponds to the process shown in Fig. 6(b). That is, a silicon film 45 is deposited in the recess 42a on the surface of which the seed layer 44 is formed. The silicon film 45 is formed conformally along the shape of the recess 42a.

[0084] In step S20, a first etching process is performed. This process corresponds to Fig. 6(c). In the first etching process, a first etching gas having a characteristic that the amount of etching is larger at the upper part than at the lower part is used to widen the opening at the upper part of the silicon film 45.

[0085] In step S30, a second etching process is performed. This process corresponds to Fig. 6(d). In the second etching process, a second etching gas having a conformal etching profile with little difference in the amount of etching between the upper and lower parts is used, and etching is performed to widen the openings of the protrusions 42b and the recesses 42c below them.

[0086] In step S40, a second film formation process is performed, which corresponds to Fig. 6(e). In the second film formation process, a film is formed to fill the opening widened by the second etching and the opening widened by the first etching.

[0087] In step S50, it is determined whether the recess 42a is filled. In Fig. 6, an example is described in which the recess 42a can be completely filled by two film formations. However, when the aspect ratio is high or the shape of the recess 42a is complex, it may not be possible to completely fill the recess 42a by two film formations.

[0088] Therefore, in step S50, it is determined whether the recess 42a is completely filled with the silicon film 45a. If it is filled, the process flow ends. On the other hand, if it is not filled, the process returns to step S20, and the first etching step to the second film forming step are repeated. When it is determined in step S50 that the recess 42a is filled with the silicon film 45, 45a, the process flow ends.

[0089] In the process flow of FIG. 8, the first etching step is E1, the second etching step is E2, and all the film forming steps are D, where DE1E2D is one cycle and is repeated.

[0090] For example, with such a process flow, the recesses 42a can be filled without generating voids within the recesses 42a.

[0091] The supply of the purge gas may be appropriately performed when switching between the film forming process and the etching process.

[0092] Fig. 9 is a process flow diagram showing an example of the method for manufacturing a semiconductor device according to the second embodiment. In Fig. 9, the same process contents as those in the method for manufacturing a semiconductor device according to the first embodiment are given the same step numbers, and descriptions of the contents of the individual steps are omitted.

[0093] In step S10, a first film formation step is performed, and a silicon film 45 is formed on the seed layer 44.

[0094] In step S20, a first etching step is performed to widen the opening in the upper part of the silicon film 45.

[0095] In step S40, a second film formation process is performed. This point is different from the manufacturing method of the semiconductor device according to the first embodiment. In other words, the first etching process and the second etching process do not necessarily need to be performed consecutively, and a film formation process may be interposed between them. Since the upper opening is enlarged in the first etching process and the silicon film 45 is conformally deposited in the film formation process, the film formation is performed while maintaining the large upper opening.

[0096] In step S30, a second etching process is performed. After the film is formed, the opening below the protrusion 42b is enlarged.

[0097] In step S41, a third film forming process is performed. In the third film forming process, a new silicon film 45a is deposited on the silicon film 45 that has been subjected to the second etching.

[0098] In step S50, it is determined whether the recess 42a is completely filled with the silicon films 45, 45a. When the recess 42a is completely filled as shown in FIG.

[0099] However, if the recess 42a is not yet filled, the process returns to step S20 and the first etching step is performed. The first etching step to the third film forming step in step S20 are repeated, and when the recess 42a is completely filled with the silicon films 45, 45a in step S50, the process flow ends.

[0100] The manufacturing method of the semiconductor device according to the second embodiment is a process of DE1DE2D, and after the first D, E1DE2D is one cycle and this cycle is repeated until the recess 42a is filled. In this way, a film forming process may be inserted between the first etching process and the second etching process. Note that the film forming process is all represented by D, since the film is formed under the same conditions without changing the conditions.

[0101] Fig. 10 is a diagram showing a process flow of the semiconductor device manufacturing method according to the third embodiment. As in Fig. 9, the same step numbers are used for the same process contents as in the process flow of Fig. 8, and the description thereof will be omitted.

[0102] In step S10, a first film formation process is performed to form a silicon film 45 on the seed layer 44.

[0103] In step S20, a first etching process is performed to widen the upper opening of silicon film 45.

[0104] In step S60, it is determined whether the thickness of the silicon film 45 formed in the first film formation step and the upper opening formed in the first etching step are appropriate. If the film thickness is insufficient or the size of the opening is insufficient, the process returns to the first film formation step S10, and the first film formation step S10 and the first etching step S20 are repeated.

[0105] If it is determined in step S60 that the thickness and upper opening of silicon film 45 are sufficient, the process proceeds to the second film forming process in step S40.

[0106] In step S30, a second etching process is performed. In the second etching process, the silicon film 45 on and below the protrusions 42b is etched to widen the openings in the silicon film 45 on and below the protrusions 42b.

[0107] In step S41, a third film forming process is performed. In the third film forming process, a new silicon film 45a is deposited on the silicon film 45 etched in the second etching process.

[0108] In step S50, it is determined whether the recess 42a is filled with the silicon films 45, 45a. If it is filled, the process flow ends.

[0109] On the other hand, if the recess 42a is not filled with the silicon films 45, 45a, the process returns to step S30 and the second etching process is performed again. The second etching process of step S30 and the third film forming process of step S41 are repeated until the recess 42a is filled with the silicon films 45, 45a.

[0110] Then, if it is determined in step S50 that the recess 42a is filled with the silicon films 45, 45a, the process flow ends.

[0111] In this way, the sequence may be one in which a cycle of DE1 is repeated, followed by D, followed by a cycle of E2D is repeated.

[0112] As described above in the first to third embodiments, the film forming step, the first etching step, and the second etching step can be performed in various combinations.

[0113] In the first to third embodiments, a judgment point is provided, but a configuration may be adopted in which an appropriate number of DE repetitions is checked in advance and a DE cycle is carried out a preset number of times.

[0114] Moreover, the order of the first etching step and the second etching step may be reversed in terms of the shape of the recess 42a, and further etching steps with different profiles may be combined.

[0115] In this way, by performing two-stage etching using different types of etching in the DED process, even if the side surface of the recess 42a is uneven, the silicon films 45, 45a can be filled without creating voids.

[0116] In this embodiment, an example has been described in which a vertical heat treatment apparatus is used as a substrate processing apparatus, but it is also possible to configure the substrate processing apparatus as a single-wafer type film formation apparatus or a semi-batch type film formation apparatus that uses a rotating table to perform ALD (Atomic Layer Deposition) on approximately 5 to 6 wafers W.

[0117] The same principle can also be applied to a substrate processing apparatus that uses plasma. That is, the semiconductor device manufacturing method and substrate processing apparatus according to the present embodiment can be widely applied to a process and substrate processing apparatus that fills a recess with a silicon film by using a DED process.

[0118] Although the preferred embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. [Explanation of symbols]

[0119] 11 Reaction tube 19 Heater 21, 31 Gas inlet pipe 23A~23E, 32 Gas supply source 24A~24E, 33 Gas supply mechanism 27 Valve 30 Control section 42, 42a recess 42b Convex part 42c Recess 43 Silicon oxide film 44 Seed Layer 45, 45a Silicone membrane W wafer

Claims

1. supplying a silicon-containing gas to a substrate having a recess on a surface thereof to deposit a silicon film in the recess; supplying a first etching gas having a first etching profile in which an etching amount differs between an upper portion and a lower portion in a depth direction of the recess to the substrate, thereby etching the silicon film in the recess; supplying a second etching gas having a second etching profile different from the first etching profile of the first etching gas to the substrate, and etching the silicon film in the recess; and depositing a new silicon film on the silicon film etched with the second etching gas, the first etching profile of the first etching gas is such that an etching amount of the upper portion of the recess in a depth direction is greater than an etching amount of the lower portion of the recess; a second etching profile of the second etching gas in which the ratio of the etching amount of the upper portion to the etching amount of the lower portion is smaller than that of the first etching profile, or the etching amount of the upper portion and the etching amount of the lower portion are equal to each other.

2. the first etching profile is a profile that widens an opening in the upper silicon film to form a shallow V-shaped opening; 2. The method for manufacturing a semiconductor device according to claim 1, wherein the second etching profile is a profile that forms a deep V-shape in the silicon film in the lower portion.

3. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the first etching gas and the second etching gas are generated by adding dilution gases at different flow rates to the same etching gas.

4. 4. The method for manufacturing a semiconductor device according to claim 3, wherein the same etching gas is chlorine.

5. 5. The method for manufacturing a semiconductor device according to claim 3, wherein the dilution gas is an inert gas.

6. 6. The method for manufacturing a semiconductor device according to claim 3, wherein a flow rate of the dilution gas of the second etching gas is greater than a flow rate of the dilution gas of the first etching gas.

7. 7. The method for manufacturing a semiconductor device according to claim 1, wherein the recess has a shape including projections and recesses on the side surface.

8. 8. The method for manufacturing a semiconductor device according to claim 1, wherein a step of supplying the first etching gas to etch the silicon film in the recess, a step of supplying the second etching gas to the substrate to etch the silicon film in the recess, and a step of depositing a new silicon film on the silicon film are repeated.

9. 9. The method for manufacturing a semiconductor device according to claim 1, further comprising, between the step of supplying the first etching gas and etching the silicon film in the recess and the step of supplying the second etching gas to the substrate and etching the silicon film in the recess, a step of depositing a new silicon film on the silicon film etched with the first etching gas.

10. supplying a silicon-containing gas to a substrate having a recess on a surface thereof to deposit a silicon film in the recess; supplying a first etching gas having a first etching profile in which an etching amount differs between an upper portion and a lower portion in a depth direction of the recess to the substrate, thereby etching the silicon film in the recess; depositing a new silicon film on the silicon film etched with the first etching gas at least once; supplying the first etching gas to etch the silicon film in the recessed portion, and depositing a new silicon film on the silicon film; supplying a second etching gas having a second etching profile different from the first etching profile of the first etching gas to the substrate, and etching the silicon film in the recess; depositing a new silicon film on the silicon film etched with the second etching gas; and performing at least one or more times a second cycle including a step of supplying the second etching gas to etch the silicon film in the recess and a step of depositing a new silicon film on the silicon film, the first etching profile of the first etching gas is such that an etching amount of the upper portion of the recess in a depth direction is greater than an etching amount of the lower portion of the recess; a second etching profile of the second etching gas in which the ratio of the etching amount of the upper portion to the etching amount of the lower portion is smaller than that of the first etching profile, or the etching amount of the upper portion and the etching amount of the lower portion are equal to each other.

11. the first etching profile is a profile that widens an opening in the upper silicon film to form a shallow V-shaped opening; 11. The method for manufacturing a semiconductor device according to claim 10, wherein the second etching profile is a profile that forms a deep V-shape in the silicon film in the lower portion.

12. 12. The method for manufacturing a semiconductor device according to claim 10, wherein the first etching gas and the second etching gas are generated by adding dilution gases at different flow rates to the same etching gas.

13. 13. The method for manufacturing a semiconductor device according to claim 12, wherein the same etching gas is chlorine.

14. 14. The method for manufacturing a semiconductor device according to claim 12, wherein the dilution gas is an inert gas.

15. 15. The method for manufacturing a semiconductor device according to claim 12, wherein a flow rate of the dilution gas of the second etching gas is greater than a flow rate of the dilution gas of the first etching gas.

16. 16. The method for manufacturing a semiconductor device according to claim 10, wherein the recess has a shape including projections and recesses on a side surface.

17. 17. The method for manufacturing a semiconductor device according to claim 10, wherein a step of supplying the first etching gas and etching the silicon film in the recess, a step of supplying the second etching gas to the substrate and etching the silicon film in the recess, and a step of depositing a new silicon film on the silicon film are repeated.

18. A processing chamber; a substrate holding member provided in the processing chamber and capable of holding a substrate having a recess formed on a surface thereof; a silicon-containing gas supply unit that supplies a silicon-containing gas to the substrate and deposits a silicon film in the recess; a first etching gas supply unit that supplies a first etching gas having a first etching profile in which an etching amount differs between an upper portion and a lower portion in a depth direction of the recess to the substrate, thereby etching the silicon film in the recess; a second etching gas supply unit that supplies a second etching gas having a second etching profile different from the first etching profile of the first etching gas to the substrate, and etches the silicon film in the recess; a control unit that causes the silicon-containing gas supply unit to supply the silicon-containing gas and deposits a new silicon film on the silicon film etched with the second etching gas, the first etching profile of the first etching gas is such that an etching amount of the upper portion of the recess in a depth direction is greater than an etching amount of the lower portion of the recess; The second etching profile of the second etching gas is a substrate processing apparatus in which the ratio of the etching amount of the upper portion to the etching amount of the lower portion is smaller than that of the first etching profile, or the etching amount of the upper portion and the etching amount of the lower portion are equal to each other.

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