Semiconductor device manufacturing method and semiconductor device manufacturing system

Abstract

To reduce residues when a sacrificial film is removed.SOLUTION: A method of manufacturing a semiconductor device includes a formation step, a processing step and a removal step. In the formation step, a sacrificial film made of a polymer having a urea bond is formed on a substrate by supplying an amine and an isocyanate to a surface of the substrate, the sacrificial film being provided in a specific region of the substrate. In the processing step, a predetermined process is performed on the substrate on which the sacrificial film is formed. In the removal step, the sacrificial film is removed by heating the substrate to depolymerize the polymer. A carbon bonded to a nitrogen atom contained in an isocyanate group of the isocyanate is a secondary or tertiary non-aromatic carbon.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Various aspects and embodiments of the present disclosure relate to a method and a system for manufacturing a semiconductor device. [Background technology]

[0002] For example, Patent Document 1 below discloses a technology in which a protective film made of a polymer having a urea bond is laminated on the surface of a layer to be protected from a specific treatment, and after the specific treatment is performed, the protective film is removed by heating the substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-80000 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a semiconductor device manufacturing method and a semiconductor device manufacturing system that can reduce residues when a sacrificial film is removed. [Means for solving the problem]

[0005] One aspect of the present disclosure is a method for manufacturing a semiconductor device, including a forming step, a processing step, and a removing step. In the forming step, a sacrificial film is formed on a specific region of the substrate by supplying an amine and an isocyanate to a surface of the substrate, the sacrificial film being composed of a polymer having a urea bond. In the processing step, a predetermined process is performed on the substrate on which the sacrificial film has been formed. In the removing step, the sacrificial film is removed by heating the substrate to depolymerize the polymer. The carbon bonded to the nitrogen atom contained in the isocyanate group of the isocyanate is a secondary or tertiary non-aromatic carbon. [Effects of the Invention]

[0006] According to various aspects and embodiments of the present disclosure, it is possible to reduce residues when removing a sacrificial film. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a flowchart showing an example of a method for manufacturing a semiconductor device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram showing an example of a manufacturing process of a semiconductor device. [Figure 3] FIG. 3 is a diagram showing an example of a polymer formation process in the first embodiment. [Figure 4] FIG. 4 is a diagram showing an example of a manufacturing process of a semiconductor device. [Figure 5] FIG. 5 is a diagram showing an example of a manufacturing process of a semiconductor device. [Figure 6] FIG. 6 is a system configuration diagram illustrating an example of a manufacturing system according to an embodiment of the present disclosure. [Figure 7] FIG. 7 is a schematic diagram showing an example of a second film forming apparatus for forming a protective film. [Figure 8] FIG. 8 is a schematic diagram showing an example of a coating device for forming a protective film. [Figure 9] FIG. 9 is a schematic diagram showing an example of an etching apparatus. [Figure 10] FIG. 10 is a schematic diagram showing an example of a heat treatment apparatus. [Figure 11] FIG. 11 shows an example of a combination of isocyanate and amine that are materials for the protective film. [Figure 12] FIG. 12 shows an example of a combination of isocyanate and amine that are materials for the protective film. [Figure 13] FIG. 13 is a diagram showing an example of the temperature at the inflection point of the mass change of the polymer and the residue rate. [Figure 14] FIG. 14 is a diagram showing an example of the change in mass of a polymer with respect to temperature. [Figure 15]FIG. 15 shows an example of the process of polymer formation when a primary amine is used. [Figure 16] FIG. 16 shows an example of the basic skeleton of an amine. [Figure 17] FIG. 17 shows other examples of secondary amine structures. [Figure 18] FIG. 18 is a diagram showing an example of the process of self-polymerization of isocyanate. [Figure 19] FIG. 19 is a diagram showing an example of the experimental results of self-polymerization of isocyanate. [Figure 20] FIG. 20 is a diagram showing an example of a basic skeleton of an isocyanate. [Figure 21] FIG. 21 shows another example of the structure of an isocyanate. [Figure 22] FIG. 22 shows examples of combinations of isocyanates and amines in the cases where structural isomers are included and where structural isomers are not included. [Figure 23] FIG. 23 is a diagram showing an example of the change in mass of a polymer with respect to temperature. [Figure 24] FIG. 24 shows examples of primary amines and secondary amines. [Figure 25] FIG. 25 shows an example of an isocyanate having an isocyanate group that includes a nitrogen atom bonded to a tertiary non-aromatic carbon. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the disclosed semiconductor device manufacturing method and semiconductor device manufacturing system will be described in detail with reference to the drawings. Note that the disclosed semiconductor device manufacturing method and semiconductor device manufacturing system are not limited to the following embodiments.

[0009] Incidentally, when a substrate on which a sacrificial film made of a polymer having a urea bond is formed is heated to a temperature at which the polymer depolymerizes, the polymer sacrificial film depolymerizes. The polymer sacrificial film is then decomposed into monomers and removed from the substrate. Polymerization and depolymerization are reversible equilibrium reactions, and as the temperature increases, depolymerization becomes dominant. Therefore, if the substrate is heated to a sufficiently high temperature, the polymer depolymerizes into monomers, and residues can be reduced.

[0010] However, in the manufacturing process of semiconductor devices, materials that are sensitive to heat may be used. Therefore, even when removing a sacrificial film, it may be difficult to heat the substrate to a high temperature. This may result in insufficient removal of the polymer, resulting in residues on the substrate.

[0011] Therefore, the present disclosure provides a technique that can reduce residues when removing a sacrificial film.

[0012] (First embodiment) [Method of manufacturing a semiconductor device] Fig. 1 is a flowchart showing an example of a method for manufacturing a semiconductor device according to an embodiment of the present disclosure. Fig. 1 illustrates a method for manufacturing a memory element as an example of a semiconductor device. Examples of memory elements include ReRAM, PcRAM, and MRAM. Hereinafter, the method for manufacturing the semiconductor device illustrated in Fig. 1 will be described with reference to Figs. 2 to 5.

[0013] To briefly explain the process illustrated in FIG. 1, a contact hole is formed in a substrate W for manufacturing a memory element to embed a metal that will serve as a conductive path for the memory element. A protective film made of a polymer containing urea bonds is formed in the position where the contact hole will be formed, thereby protecting the electrode film formed below the protective film from damage caused by over-etching that may occur during the formation of the contact hole. This protective film is a sacrificial film, and is removed after the contact hole is formed and before the metal that will serve as the conductive path is embedded. In the process illustrated in FIG. 1, a substrate W is first prepared, on which an electrode 12 surrounded by an insulating film 11 is provided, as shown in FIG. 2(a), for example.

[0014] First, as shown in FIG. 2(b), for example, a memory element film 13 is formed on a substrate W (S10). The memory element film 13 may be, for example, a metal oxide film used in ReRAM (resistance random access memory). Then, as shown in FIG. 2(c), for example, an electrode film 14 is formed on the memory element film 13 (S11). The electrode film 14 may be, for example, a stacked film of titanium nitride and tungsten.

[0015] Next, as shown in FIG. 2(d), for example, a protective film 15 is formed on the electrode film 14 (S12). Step S12 is an example of a forming process. The protective film 15 protects specific regions of the substrate W, such as the electrode film 14, from predetermined processes such as etching. In this embodiment, the protective film 15 is a polyurea film produced by copolymerization of an isocyanate and a secondary amine, as shown in FIG. 3, for example. R1, R2, and X in FIG. 3 are, for example, alkyl groups or cycloalkyl groups, and n is an integer of 2 or greater. In this embodiment, the protective film 15 is formed when the temperature of the substrate W is set to, for example, 80°C. After the predetermined process is performed on the substrate W, the protective film 15 is depolymerized into an isocyanate and a secondary amine by heating the substrate W to a temperature of 250°C or higher (for example, 400°C). This removes the protective film 15 from the substrate W.

[0016] Next, as shown in FIG. 4(e), for example, a mask film 16 is formed on the protective film 15 (S13). The mask film 16 may be, for example, a boron-containing silicon film. The boron-containing silicon film is formed using, for example, a silane-based gas and B2H6 gas, which is a doping gas. Then, the substrate W is etched (S14). In step S14, a resist pattern is formed on the mask film 16, and the mask film 16 is etched along the resist pattern. Then, the protective film 15, the electrode film 14, and the memory element film 13 are etched using the mask film 16 etched along the resist pattern as a hard mask. As a result, for example, a pattern shown in FIG. 4(f) is formed on the substrate W.

[0017] 4(g), for example, a sealing film 17 is formed so as to cover the surface of the laminate including the mask film 16, the protective film 15, the electrode film 14, and the memory element film 13 (S15). The sealing film 17 is made of, for example, polyimide, and is provided to enhance the heat resistance of the protective film 15.

[0018] Next, as shown in FIG. 4(h), a silicon oxide film 18 is formed on the sealing film 17 (S16). The silicon oxide film 18 is used as an element isolation film for electrically isolating elements from each other. The silicon oxide film 18 is formed by CVD (Chemical Vapor Deposition) at a process temperature of 300° C. in a vacuum atmosphere, for example.

[0019] Next, the substrate W is etched to form contact holes 19, for example, as shown in FIG. 5(i) (S17). Step S17 is an example of a processing step. In step S17, a mask having openings is formed on the silicon oxide film 18, and the substrate W is etched through the mask until the protective film 15 is exposed. As a result, the contact holes 19 are formed at positions corresponding to the openings in the mask.

[0020] Next, the substrate W is heated to depolymerize the protective film 15, and the protective film 15 is removed (S18), for example, as shown in FIG. 5(j). Step S18 is an example of a removal step. Then, as shown in FIG. 5(k), for example, a conductive path 21 is formed in the contact hole 19 (S19). In step S19, a metal such as copper is embedded in the contact hole 19, and excess metal is removed by CMP (Chemical Mechanical Polishing), thereby forming the conductive path 1. Then, the method for manufacturing a semiconductor device shown in this flowchart is completed.

[0021] [Manufacturing System 10] The manufacturing method illustrated in FIG. 1 is realized, for example, by a manufacturing system 10 shown in FIG. 6. FIG. 6 is a system configuration diagram showing an example of the manufacturing system 10 according to an embodiment of the present disclosure. The manufacturing system 10 includes a first film formation apparatus 2, a second film formation apparatus 4, an etching apparatus 5, and a heat treatment apparatus 6. The manufacturing system 10 is a multi-chamber type vacuum processing system. The manufacturing system 10 manufactures a semiconductor device using the film formation apparatus 200, the second film formation apparatus 4, the etching apparatus 5, and the heat treatment apparatus 6.

[0022] The first film formation apparatus 2 forms a predetermined film on the substrate W. The first film formation apparatus 2 performs, for example, steps S10, S11, S13, S15, S16, and S19 in the manufacturing method illustrated in FIG. 1. The second film formation apparatus 4 forms, on the substrate W, a protective film 15 made of a polymer containing a urea bond. The second film formation apparatus 4 performs, for example, step S12 in the manufacturing method illustrated in FIG. 1. The etching apparatus 5 performs etching on the substrate W. The etching apparatus 5 performs, for example, steps S14 and S17 in the manufacturing method illustrated in FIG. 1. The etching apparatus 5 is an example of a processing apparatus. The heat treatment apparatus 6 performs a process of removing the protective film 15 by heating the substrate W. The heat treatment apparatus 6 performs, for example, step S18 in the manufacturing method illustrated in FIG.

[0023] The first film formation apparatus 2, the second film formation apparatus 4, the etching apparatus 5, and the heat treatment apparatus 6 are connected to the four side walls of a vacuum transfer chamber 101, which has a heptagonal planar shape, via gate valves G. Three load lock chambers 102 are connected to the other three side walls of the vacuum transfer chamber 101 via gate valves G1. Each of the three load lock chambers 102 is connected to an atmospheric transfer chamber 103 via gate valves G2.

[0024] The vacuum transfer chamber 101 is evacuated by a vacuum pump and maintained at a predetermined vacuum level. A transfer device 106 such as a robot arm is provided inside the vacuum transfer chamber 101. The transfer device 106 transfers substrates W between the first film formation device 2, the second film formation device 4, the etching device 5, the heat treatment device 6, and their respective load lock chambers 102. The transfer device 106 has two arms 107a and 107b that can move independently.

[0025] A plurality of ports 105 are provided on the side of the atmospheric transfer chamber 103 for attaching carriers (FOUP (Front-Opening Unified Pod) or the like) C that accommodate substrates W. An alignment chamber 104 is also provided on the side wall of the atmospheric transfer chamber 103 for aligning the substrates W. A downflow of clean air is formed within the atmospheric transfer chamber 103.

[0026] A transfer device 108 such as a robot arm is provided in the atmospheric transfer chamber 103. The transfer device 108 transfers substrates W between each carrier C, each load lock chamber 102, and the alignment chamber 104.

[0027] The control device 100 has a memory, a processor, and an input / output interface. The memory stores programs executed by the processor, recipes including conditions for each process, and the like. The processor executes the programs read from the memory and controls each part of the manufacturing system 10 via the input / output interface based on the recipes stored in the memory.

[0028] [Configuration of second film forming apparatus 4] 7 is a schematic diagram showing an example of a second film formation apparatus 4 for forming a protective film 15. The second film formation apparatus 4 has a vacuum vessel 40 that defines a vacuum atmosphere. A stage 44 on which a substrate W is placed is provided within the vacuum vessel 40. The stage 44 is provided with a temperature control mechanism for adjusting the temperature of the substrate W to a predetermined temperature. A shower head 43 is provided at the top of the vacuum vessel 40. Furthermore, an exhaust mechanism 45 is provided at the bottom of the vacuum vessel 40 that exhausts gas within the vacuum vessel 40 and controls the pressure inside the vacuum vessel 40 to a predetermined value.

[0029] The raw material supply source 41a contains a liquid isocyanate, which is a raw material monomer. The raw material supply source 42a contains a liquid amine, which is a raw material monomer. The vaporizer 41b vaporizes the isocyanate liquid contained in the raw material supply source 41a and supplies it to the shower head 43 via the pipe 41c. The vaporizer 42b vaporizes the amine liquid contained in the raw material supply source 42a and supplies it to the shower head 43 via the pipe 42c. The isocyanate and amine vapors supplied to the shower head 43 are supplied into the vacuum chamber 40 in a shower-like manner. The shower head 43 has a number of outlet holes formed on its underside, and the isocyanate vapor and the amine vapor are discharged into the vacuum chamber 40 from separate outlet holes. The isocyanate vapor and the amine vapor supplied into the vacuum chamber 40 polymerize on the substrate W to form a protective film 15 having urea bonds.

[0030] The protective film 15 may be formed on the substrate W by a coating apparatus 3 such as that shown in FIG. 8. FIG. 8 is a schematic diagram illustrating an example of a coating apparatus 3 for forming the protective film 15. The coating apparatus 3 includes a vacuum chuck 31, a cup module 32, a guide member 33, and a discharge space 34. The vacuum chuck 31 holds the substrate W by suction and is rotated by a rotation mechanism 30. The guide member 33 has a cylindrical structure with an outer peripheral wall and an inner peripheral wall extending downward. The discharge space 34 is formed between the outer cup 35 and the outer peripheral wall so that exhaust and drainage can be performed around the entire circumference. The lower side of the discharge space 34 is designed to separate gas and liquid. A heating unit 39, such as a light-emitting diode, is disposed below the vacuum chuck 31, and the heating unit 39 heats the substrate W to a predetermined temperature.

[0031] The raw material supply source 38a contains an isocyanate liquid, which is a raw material monomer. The raw material supply source 38b contains an amine liquid, which is a raw material monomer. The nozzle 38 mixes the isocyanate liquid contained in the raw material supply source 38a and the amine liquid contained in the raw material supply source 38b, and supplies the mixture to the center of the substrate W. Then, the substrate W held by the vacuum chuck 31 is rotated by the rotation mechanism 30, so that the mixed liquid supplied onto the substrate W spreads over the entire upper surface of the substrate W, and a protective film 15 is formed on the upper surface of the substrate W.

[0032] [Configuration of Etching Equipment 5] FIG. 9 is a schematic diagram showing an example of an etching apparatus 5. The etching apparatus 5 shown in FIG. 9 can perform etching using capacitively coupled plasma. The etching apparatus 5 has a processing vessel 51 made of a conductive material. The processing vessel 51 is grounded. An exhaust mechanism 52 is connected to the processing vessel 51, and the exhaust mechanism 52 exhausts gas from the processing vessel 51, controlling the inside of the processing vessel 51 to a predetermined pressure.

[0033] A stage 53 on which a substrate W is placed is provided within the processing vessel 51. A heater 50 for heating the substrate W is provided within the stage 53. The stage 53 is electrically connected to the bottom of the processing vessel 51 and functions as an anode electrode. A shower head 54 is provided above the stage 53 so as to face the upper surface of the stage 53. The shower head 54 is supported on the upper part of the processing vessel 51 via an insulating member 54A. A power source 55 for supplying high-frequency power for generating plasma is connected to the shower head 54. The shower head 54 functions as a cathode electrode relative to the stage 53.

[0034] The gas supply source 56A supplies an etching gas. The gas supply source 57A supplies an inert gas such as N2 gas. The flow rate controller 56B adjusts the flow rate of the etching gas supplied from the gas supply source 56A and supplies it into the diffusion space 58 of the shower head 54. The flow rate controller 57B adjusts the flow rate of the inert gas supplied from the gas supply source 57A and supplies it into the diffusion space 58 of the shower head 54. The gas supplied into the diffusion space 58 diffuses within the diffusion space 58 and is supplied in a shower-like manner into the processing vessel 51 from a plurality of outlets 59 formed on the bottom surface of the diffusion space 58.

[0035] The etching apparatus 5 includes a control unit 500. The control unit 500 includes a memory, a processor, and an input / output interface. The memory stores programs executed by the processor, recipes including conditions for each process, and the like. The processor executes the programs read from the memory and controls each part of the etching apparatus 5 via the input / output interface based on the recipes stored in the memory. Specifically, the processor controls the on / off of the power source 55, the exhaust rate of the exhaust mechanism 52, the gas flow rates controlled by the flow rate controllers 56B and 57B, the power supplied to the heater 50, and the like.

[0036] For example, a substrate W (see FIG. 4(h)) having a silicon oxide film 18 formed thereon is loaded into a processing chamber 51 of an etching apparatus 5 and placed on a stage 53. Although not shown in FIG. 4(h), a mask having an opening formed in an area corresponding to the contact hole 19 is provided on the silicon oxide film 18. The processing chamber 51 is then evacuated by an exhaust mechanism 52, and when the pressure inside the processing chamber 51 reaches a predetermined level, an etching gas for forming the contact hole 19 is discharged from a shower head 54, and high-frequency power is supplied to the shower head 54 from a power source 55. This forms an electric field between the shower head 54 and the stage 53, converting the etching gas into plasma. The silicon oxide film 18 is then etched by ions and active species contained in the plasma, forming the contact hole 19, and the protective film 15 is exposed on the surface of the substrate W. The mask is then removed by ashing using plasma, and the surface of the substrate W becomes, for example, as shown in FIG. 5(i). Then, the supply of the etching gas and the supply of the high frequency power are stopped, an inert gas is supplied into the processing chamber 51, and the substrate W is unloaded from the processing chamber 51.

[0037] [Configuration of Heat Treatment Device 6] 10 is a schematic diagram showing an example of a heat treatment apparatus 6. The heat treatment apparatus 6 includes a vessel 61, which is a substantially cylindrical vacuum vessel with its longitudinal direction oriented vertically. The vessel 61 has a double-tube structure consisting of an inner tube 62 and an outer tube 63 with a ceiling that covers the inner tube 62 and is formed at a fixed distance from the inner tube 62. The inner tube 62 and the outer tube 63 are made of a heat-resistant material such as quartz.

[0038] A cylindrical manifold 64 made of stainless steel is disposed below the outer pipe 63. The manifold 64 is airtightly connected to the lower end of the outer pipe 63. The inner pipe 62 protrudes from the inner wall of the manifold 64. The inner pipe 62 is supported by a support ring 65 formed integrally with the manifold 64.

[0039] A lid 66 is disposed below the manifold 64. The lid 66 is configured to be able to move up and down between an elevated position and a lowered position by a boat elevator (not shown). FIG. 10 illustrates the lid 66 in the elevated position. In this elevated position, the lid 66 closes an opening 67 of the vessel 61 below the manifold 64, thereby maintaining the interior of the vessel 61 airtight. A stage 68 is provided above the lid 66. A boat 7, which serves as a substrate holder, is placed on the stage 68. A heat insulating material 79 is provided between the stage 68 and the lid 66. A rotation mechanism 69 is also provided on the lid 66. The rotation mechanism 69 rotates the stage 68 vertically during heat treatment of the substrate W.

[0040] A heat insulator 71 is provided around the container 61 so as to surround the container 61. A heater 72, which is a heating unit and is made of, for example, a resistance heating element, is provided on the inner wall surface of the heat insulator 71. The inside of the container 61 can be heated by the heater 72. A nozzle 73 is provided below the support ring 65 in the manifold 64. The nozzle 73 is connected via a flow controller 601 to a gas supply source 600 that supplies an inert gas such as N2 gas, and can supply the inert gas into the inner tube 62. One end of an exhaust pipe 74 that exhausts the inside of the container 61 is connected to the side surface of the manifold 64 above the support ring 65, and the other end of the exhaust pipe 74 is connected to an exhaust mechanism 602.

[0041] The boat 7 includes a top plate 75 and a bottom plate 76 facing each other. The top plate 75 and the bottom plate 76 are formed horizontally and are connected horizontally to one end and the other end of three support columns 77 (only two of which are illustrated in FIG. 10 ) that extend vertically up and down. Each support column 77 is provided with a number of support parts (not shown) that support the rear surfaces of the substrates W in the vertical direction, and by being supported by these support parts, a number of substrates W are held in a shelf-like manner at intervals in the vertical direction.

[0042] The heat treatment apparatus 6 has a control unit 603. The control unit 603 has a memory, a processor, and an input / output interface. The memory stores programs executed by the processor, recipes including conditions for each process, and the like. The processor executes the programs read from the memory and controls each part of the heat treatment apparatus 6 via the input / output interface based on the recipes stored in the memory. Specifically, the processor controls the amount of exhaust by the exhaust mechanism 602, the flow rate of the inert gas supplied to the container 61 by the exhaust mechanism 602, the power supplied to the heater 72, and the like.

[0043] [Example] 11 and 12 are diagrams showing examples of combinations of isocyanates and amines that are materials for the protective film 15. The comparative example is a combination of an isocyanate having a benzene ring and a primary amine having a cyclohexane ring. Example 1 is a combination of an isocyanate having a cyclohexane ring and a primary amine having a cyclohexane ring. Examples 2 and 3 are combinations of an isocyanate with a chain structure and a primary amine with a cyclohexane ring. Examples 4 and 5 are combinations of an isocyanate with a chain structure and a primary amine with a chain structure. Examples 6 to 8 are combinations of an isocyanate with a chain structure and a secondary amine with a chain structure.

[0044] [Experimental Results] Fig. 13 is a diagram showing an example of the temperature and residue ratio at the inflection point of the mass change of a polymer. As the temperature increases, the depolymerization reaction of a polymer of isocyanate and amine is promoted more than the polymerization reaction, and the mass of the polymer decreases. The temperature at which the mass of the polymer rapidly decreases with increasing temperature is the inflection point of the mass change of the polymer.

[0045] For example, as shown in Figure 13, the inflection points of the mass change of the polymers in Examples 1 to 8 are higher than those in the comparative example. That is, it can be said that the polymers in Examples 1 to 8 have better temperature stability than the comparative example. Therefore, from the viewpoint of temperature stability, the polymers formed by combining Examples 1 to 8 are preferable.

[0046] As shown in FIG. 13, the polymer residue rate was 95% or higher at 550°C in all Examples. Meanwhile, at 450°C, the residue rates were 95% or higher in the Comparative Example and Examples 6 to 8. In removing the protective film 15, it is preferable to remove the protective film 15 at a lower temperature to minimize adverse effects on other heat-sensitive structures, such as wiring materials, provided on the substrate W. In removing the protective film 15, it is preferable to heat the substrate W to a temperature in the range of 400 to 500°C. Furthermore, the residue rates of Examples 6 to 8 were lower than that of the Comparative Example. Therefore, from the perspectives of temperature stability and residue rate, the results of FIG. 13 suggest that the polymer formed by the combination of Examples 6 to 8 is preferable. That is, a secondary amine is preferable as the amine.

[0047] 14 is a graph showing an example of the change in polymer mass with respect to temperature. For example, as shown in FIG. 14, in Example 7, the change in polymer mass is 95% or more at around 400°C, and the polymer is almost completely removed. On the other hand, in Examples 1 and 3, the change in mass is smaller than in Example 7 at around 400°C, and more residue remains. Therefore, in terms of removing the polymer at a lower temperature, the polymer formed by the combination of Example 7 is preferable to the polymer formed by the combination of Examples 1 and 3.

[0048] Here, the polymer formed by isocyanate and amine is depolymerized into isocyanate and amine by heating. However, when the polymer is combined with isocyanate and primary amine, a dehydration reaction may occur during heating, resulting in the production of other polymers containing carbodiimide, as shown in Figure 15. Such polymers are not depolymerized by heating and are not removed by heating, but instead become carbonized. Therefore, the combination of isocyanate and primary amine is thought to leave more residue than the combination of isocyanate and secondary amine. Therefore, from the perspective of reducing residue, the combination of isocyanate and secondary amine is preferred.

[0049] Examples of the basic skeleton of such secondary amines include monofunctional amines as shown in Figure 16(a) and bifunctional amines as shown in Figure 16(b). R and X shown in Figures 16(a) and 16(b) are, for example, alkyl groups or cycloalkyl groups. Also possible secondary amines include compounds as shown in Figures 17(a) and 17(b).

[0050] (Second embodiment) In the first embodiment, the protective film 15 is formed of a polymer having a urea bond by combining an isocyanate and a secondary amine. However, as shown in FIG. 18, for example, isocyanate may undergo self-polymerization at a temperature of about 150°C. The self-polymerized isocyanate polymer does not return to the original isocyanate even when heated, but remains as a residue. Therefore, in terms of reducing the residue when the protective film 15 is removed by heating, it is preferable to form the protective film 15 using an isocyanate with a structure that is not prone to self-polymerization. In this embodiment, the protective film 15 is formed using an isocyanate with a structure that is not prone to self-polymerization.

[0051] [Experimental Results] FIG. 19 shows an example of experimental results of isocyanate self-polymerization. In the experiment, an isocyanate liquid was maintained at 150°C for one month, and the occurrence of self-polymerization was determined based on the presence or absence of discoloration. In Example 9, an isocyanate having a structure in which an isocyanate group is bonded to a benzene ring was used. In Example 10, an isocyanate having a structure in which an isocyanate group is bonded to a benzene ring via a carbon was used. In Example 11, an isocyanate having a structure in which an isocyanate group is bonded to a cyclohexane ring via a carbon was used. In Example 12, an isocyanate having a chain structure was used. In Example 13, an isocyanate having a structure in which an isocyanate group is bonded to a cyclohexane ring was used.

[0052] As shown in FIG. 19, discoloration was observed with the isocyanates of Examples 9 and 10, indicating that self-polymerization had occurred. Slight discoloration was observed with the isocyanate of Example 12, indicating that slight self-polymerization had occurred. On the other hand, no discoloration was observed with the isocyanates of Examples 11 and 13, indicating that almost no self-polymerization had occurred. In other words, by using the isocyanates of Examples 11 to 13, it is possible to reduce residues compared to when the isocyanates of Examples 9 or 10 are used.

[0053] The isocyanates of Examples 11 to 13 have a common structure, as shown in FIG. 20, for example. FIG. 20 is a diagram showing an example of the basic skeleton of an isocyanate. In FIG. 20, two of R1 to R3 are carbon compounds, and the remaining one is a carbon compound or a hydrogen atom. That is, in the basic skeleton of the isocyanate shown in FIG. 20, the nitrogen atom contained in the isocyanate group is bonded to a secondary or tertiary non-aromatic carbon. The non-aromatic carbon is, for example, carbon that constitutes a hydrocarbon compound with a chain structure or a cyclic structure. By using an isocyanate with such a structure, it is possible to further reduce residue when removing the protective film 15 by heating.

[0054] Although Fig. 20 illustrates a monofunctional isocyanate having one isocyanate group, the effect of reducing residues can also be achieved with a bifunctional isocyanate having two isocyanate groups. As bifunctional isocyanates having the basic skeleton illustrated in Fig. 20, structures such as those illustrated in Figs. 21(a) to 21(c) can also be considered.

[0055] [Structural isomer] FIG. 22 shows examples of combinations of isocyanates and amines containing structural isomers and not containing structural isomers. In Example 14, both the isocyanate and the amine contain cis and trans structural isomers. In Example 15, only the trans structural isomers are contained for the isocyanate, and both the cis and trans structural isomers are contained for the amine. In Example 16, both the isocyanate and the amine contain only the trans structural isomers.

[0056] FIG. 23 is a graph showing an example of the change in polymer mass with temperature. For example, as shown in FIG. 23, around 400°C, Example 14, in which structural isomers are contained in both the isocyanate and the amine, exhibits a larger mass change than Examples 15 and 16, in which structural isomers are not contained in at least one of the isocyanate and the amine. Therefore, around 400°C, Example 14 leaves less residue than Examples 15 and 16. Furthermore, comparing Example 15 and Example 16, around 400°C, Example 15, in which structural isomers are contained in the amine, has a larger mass change than Example 16, in which structural isomers are not contained in either the isocyanate or the amine. Therefore, around 400°C, Example 15 leaves less residue than Example 16.

[0057] It is known that structural isomers, especially trans isomers, have high crystallinity. Therefore, polymers formed solely from monomers having only trans isomers are considered to have high crystallinity. As the crystallinity of a polymer increases, more thermal energy is required to break down the crystalline structure, which is thought to result in a higher decomposition temperature of the polymer. Therefore, polymers formed using monomers containing structural isomers can be removed at lower temperatures. In other words, from the perspective of low-temperature removal performance, Examples 14 and 15 are preferred over Example 16, and Example 14 is preferred over Example 15. Therefore, it is preferable that the isocyanate contains a structural isomer. It is also preferable that the amine contains a structural isomer.

[0058] For example, preferred examples of the structures of amines and isocyanates are those shown in FIGS. 24 and 25. FIG. 24 shows examples of primary amines and secondary amines. FIG. 25 shows an example of an isocyanate having an isocyanate group containing a nitrogen atom bonded to a tertiary non-aromatic carbon. A protective film 15 of a polyurea film is formed using a combination of an amine having any of the structures shown in FIG. 24 and an isocyanate having any of the structures shown in FIG. 25. It is assumed that the amines shown in FIG. 24 and the isocyanates shown in FIG. 25 are both monomers containing structural isomers.

[0059] The above describes the embodiments. As described above, the method for manufacturing a semiconductor device in the above-described embodiments includes a forming step, a processing step, and a removing step. In the forming step, an amine and an isocyanate are supplied to the surface of the substrate W, thereby forming a protective film 15 on the substrate W in a specific region of the substrate W. The protective film 15 is composed of a polymer having a urea bond. In the processing step, a predetermined process such as etching is performed on the substrate W on which the protective film 15 is formed. In the removing step, the substrate W is heated to depolymerize the polymer, thereby removing the protective film 15. The carbon bonded to the nitrogen atom contained in the isocyanate group of the isocyanate is a secondary or tertiary non-aromatic carbon. This reduces residue when the protective film 15 is removed by heating.

[0060] In the above-described embodiment, the carbon bonded to the nitrogen atom contained in the isocyanate group is a carbon that constitutes a hydrocarbon compound having a chain structure or a cyclic structure. The amine is a secondary amine. This can reduce residues when the protective film 15 is removed by heating.

[0061] In the above-described embodiment, in the removal step, the substrate W is heated to a temperature in the range of 400° C. to 500° C. This reduces the influence of the protective film 15 on other heat-sensitive structures, such as wiring materials, provided on the substrate W during removal.

[0062] In the above-described embodiment, it is preferable that the isocyanate does not contain structural isomers, which can further reduce residues when the protective film 15 is removed by heating.

[0063] In the above-described embodiment, the amine may be a bifunctional amine having two secondary amine functional groups. Use of such an amine can also reduce residues when removing the protective film 15 by heating.

[0064] In the above-described embodiment, the isocyanate may be a bifunctional isocyanate having two isocyanate groups. Use of such an amine can also reduce residues when removing the protective film 15 by heating.

[0065] The semiconductor device manufacturing system 10 according to the embodiment includes a second film formation apparatus 4, an etching apparatus 5, and a heat treatment apparatus 6. The second film formation apparatus 4 supplies an amine and an isocyanate to the surface of the substrate W to form a protective film 15 on a specific region of the substrate W, the protective film 15 being composed of a polymer having a urea bond. The etching apparatus 5 performs a predetermined process, such as etching, on the substrate W on which the protective film 15 has been formed. The heat treatment apparatus 6 heats the substrate W that has been subjected to the predetermined process to depolymerize the polymer, thereby removing the protective film 15. The carbon bonded to the nitrogen atom contained in the isocyanate group of the isocyanate is a secondary or tertiary non-aromatic carbon. This reduces residue when the protective film 15 is removed by heating.

[0066] In the above-described embodiment, the heat treatment device 6 heats the substrate W to a temperature in the range of 400° C. to 500° C. This reduces the influence of the protective film 15 on other heat-sensitive structures, such as wiring materials, provided on the substrate W during removal.

[0067] [others] The technology disclosed in this application is not limited to the above-described embodiment, and various modifications are possible within the scope of the gist thereof.

[0068] For example, the first and second embodiments described above can be combined. Specifically, the protective film 15 may be formed using an isocyanate in which the carbon bonded to the nitrogen atom contained in the isocyanate group is a secondary or tertiary non-aromatic carbon, and a secondary amine. This can further reduce residue when the protective film 15 is removed by heating.

[0069] In the above-described embodiment, the protective film 15 made of a polymer having a urea bond is used as an etching stopper in the manufacturing process of a memory element. However, the disclosed technology is not limited to this. If the polymer having a urea bond is used as a sacrificial film, the protective film 15 can also be used to create an air gap. For example, the protective film 15 is embedded in a recess provided in the substrate W, and a sealing film is laminated on the protective film 15 in the recess. Then, by heating the substrate W, the protective film 15 is depolymerized and becomes a monomer, which is then removed from the recess via the sealing film. This forms an air gap between the sealing film and the recess.

[0070] It should be noted that the disclosed embodiments are illustrative in all respects and should not be considered 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]

[0071] W substrate 10 Manufacturing Systems 11. Insulating film 12 electrodes 13 Memory element film 14 Electrode membrane 15 Protective film 16 Mask membrane 17 Sealing film 18 Silicon oxide film 19 Contact Hole 21 Conductive Path 2. First film deposition equipment 3 Coating equipment 4. Second film deposition equipment 5. Etching equipment 6. Heat Treatment Equipment

Claims

1. a forming step of forming a sacrificial film on a substrate by supplying an amine and an isocyanate to a surface of the substrate, the sacrificial film being provided in a specific region of the substrate and being composed of a polymer having a urea bond; a processing step of performing a predetermined process on the substrate on which the sacrificial film is formed; a removing step of removing the sacrificial film by heating the substrate to depolymerize the polymer; Including, the carbon bonded to the nitrogen atom contained in the isocyanate group of the isocyanate is a secondary or tertiary non-aromatic carbon, The method for producing a semiconductor device, wherein the isocyanate contains a structural isomer.

2. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the carbon bonded to the nitrogen atom contained in the isocyanate group is carbon that constitutes a hydrocarbon compound having a chain structure or a cyclic structure.

3. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the amine is a secondary amine.

4. 4. The method for manufacturing a semiconductor device according to claim 1, wherein the substrate is heated to a temperature in the range of 400.degree. C. to 500.degree. C. in the removing step.

5. The method for manufacturing a semiconductor device according to claim 1 , wherein the amine includes a structural isomer.

6. 6. The method for manufacturing a semiconductor device according to claim 1, wherein the amine is a bifunctional amine having two secondary amine functional groups.

7. 7. The method for manufacturing a semiconductor device according to claim 1, wherein the isocyanate is a bifunctional isocyanate having two isocyanate groups.

8. a film forming apparatus for forming a sacrificial film on a substrate by supplying an amine and an isocyanate to a surface of the substrate, the sacrificial film being provided on a specific region of the substrate and being made of a polymer having a urea bond; a processing device that performs a predetermined process on the substrate on which the sacrificial film is formed; a heat treatment device for removing the sacrificial film by heating the substrate on which the predetermined treatment has been performed to depolymerize the polymer; Equipped with the carbon bonded to the nitrogen atom contained in the isocyanate group of the isocyanate is a secondary or tertiary non-aromatic carbon, The system for manufacturing a semiconductor device, wherein the isocyanate contains a structural isomer.

9. 9. The system for manufacturing a semiconductor device according to claim 8, wherein the carbon bonded to the nitrogen atom contained in the isocyanate group is carbon that constitutes a hydrocarbon compound having a chain structure or a cyclic structure.

10. 10. The system for manufacturing a semiconductor device according to claim 8, wherein the amine is a secondary amine.

11. 11. The semiconductor device manufacturing system according to claim 8, wherein the heat treatment device heats the substrate to a temperature in the range of 400.degree. C. to 500.degree. C.

12. The semiconductor device manufacturing system according to claim 8 , wherein the amine includes a structural isomer.

13. 13. The system for manufacturing a semiconductor device according to claim 8, wherein the amine is a bifunctional amine having two secondary amine functional groups.

14. 14. The system for manufacturing a semiconductor device according to claim 8, wherein the isocyanate is a bifunctional isocyanate having two isocyanate groups.

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