JP2009200501A - Method of manufacturing semiconductor apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor apparatus preventing a semiconductor constituent atom from sublimating from the back side of a semiconductor substrate during a heat treatment process, and to provide a method of managing a semiconductor manufacturing process. <P>SOLUTION: The method of manufacturing a semiconductor apparatus having a step of forming a gate insulation film on a semiconductor substrate 10 includes the steps of: forming an insulation film 12 to cover the surface side and the back side of the semiconductor substrate prior to a step of forming the gate insulation film; etch-removing the insulation film on the surface side of the semiconductor substrate; and heat-treating the semiconductor substrate while the insulation film exists on the back side of the semiconductor substrate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor device manufacturing method and a semiconductor manufacturing process management method.

  Recently, attention has been paid to hydrogen annealing, that is, heat treatment in an atmosphere containing hydrogen as a pretreatment when forming a gate insulating film.

  The hydrogen annealing is performed for the purpose of planarizing the surface of the silicon substrate by migrating silicon on the surface of the silicon substrate and removing a natural oxide film formed on the surface of the silicon substrate.

  If hydrogen annealing is performed as a pretreatment for the step of forming the gate insulating film, a high-quality gate insulating film can be formed, and a semiconductor device having a transistor with favorable electrical characteristics can be manufactured.

JP 2001-102321 A JP 2001-274154 A JP-A-10-313012 JP 2000-340644 A JP 2001-102386 A JP 9-326396 A

  However, when hydrogen annealing is performed, silicon is sublimated from the back surface side, that is, the lower surface side of the silicon substrate. A temperature sensor or the like is provided below the place where the silicon substrate is placed in the chamber. When silicon sublimates from the back side of the silicon substrate, the sublimated silicon adheres to a temperature sensor or the like. If silicon adheres to the temperature sensor, the measurement accuracy of the sensor is lowered, and the process controllability is lowered. In order to ensure process controllability, a semiconductor manufacturing apparatus such as an RTP (Rapid Thermal Process) apparatus must be frequently maintained, resulting in a decrease in manufacturing efficiency.

  Similar problems may occur when managing the manufacturing process of a semiconductor device. That is, when managing the manufacturing process of a semiconductor device, for example, a gate insulating film is formed on a semiconductor substrate for inspection, and the gate insulating film is inspected. Maintenance etc. are performed. When the gate insulating film is formed, hydrogen annealing similar to the above is performed as a pretreatment, and therefore, silicon from the back side of the silicon substrate is sublimated also during this hydrogen annealing.

By the way, in the above-mentioned Patent Document 1, when the semiconductor wafer is heat-treated, O ₂ gas is supplied to the back side of the semiconductor wafer, and an oxide film is formed on the back side of the semiconductor wafer. A technique for preventing silicon from sublimating is disclosed. However, the technique disclosed in Patent Document 1 has a disadvantage that O ₂ gas flows into the surface side of the semiconductor wafer, that is, the upper surface side, and an undesired silicon oxide film is generated on the surface side of the semiconductor wafer. At this time, since the film thickness of the silicon oxide film generated on the surface of the semiconductor wafer is not stable, it is extremely difficult to control the gate insulating film to a desired film thickness.

  An object of the present invention is to provide a semiconductor device manufacturing method and a semiconductor manufacturing process management method capable of preventing sublimation of semiconductor constituent atoms from the back surface side of a semiconductor substrate without causing the above-described adverse effects during heat treatment. Is to provide.

  The above object is a method of manufacturing a semiconductor device including a step of forming a gate insulating film on a semiconductor substrate, and covers the front side and the back side of the semiconductor substrate before the step of forming the gate insulating film. Forming an insulating film; etching and removing the insulating film on the front surface side of the semiconductor substrate; and heat-treating the semiconductor substrate in a state where the insulating film exists on the back surface side of the semiconductor substrate. And a process for manufacturing the semiconductor device.

  Another object of the present invention is to provide a semiconductor manufacturing process management method including a step of forming a gate insulating film on a semiconductor substrate for inspection and a step of inspecting the gate insulating film, wherein the gate insulating film is formed. Before the step, a step of forming an insulating film so as to cover the front surface side and the back surface side of the semiconductor substrate for inspection, a step of etching away the insulating film on the front surface side of the semiconductor substrate for inspection, And a step of heat-treating the semiconductor substrate in a state where the insulating film is present on the back surface side of the semiconductor substrate for inspection.

  Another object of the present invention is to provide a semiconductor manufacturing process management method including a step of forming a gate insulating film on a semiconductor substrate for inspection and a step of inspecting the gate insulating film, wherein the gate insulating film is formed. Before the step, an insulating film is formed on the back side of the semiconductor substrate for inspection, and the semiconductor substrate is heat-treated in a state where the insulating film exists on the back side of the semiconductor substrate for inspection And a process for managing a semiconductor manufacturing process.

  Further, the object is to form a second insulating film so as to cover the front surface side and the back surface side of the semiconductor substrate on which the first insulating film is formed on the back surface side, and the front surface side and the back surface side. Forming a semiconductor film so as to cover the second insulating film; etching removing the semiconductor film on the back surface; and the second insulating film on the back surface side of the semiconductor substrate. And a step of heat-treating the semiconductor substrate in a state of being present.

  Further, the object is to form a first insulating film so as to cover the front surface side and the back surface side of the semiconductor substrate, and to etch away the first insulating film on the front surface side of the semiconductor substrate. Forming a second insulating film so as to cover the front surface side and the back surface side of the semiconductor substrate; and forming a semiconductor film so as to cover the second insulating film on the front surface side and the back surface side A step of etching and removing the semiconductor film on the back surface side, and a step of heat-treating the semiconductor substrate in a state where the second insulating film is present on the back surface side of the semiconductor substrate. This is achieved by a method for manufacturing a semiconductor device.

  As described above, according to the present invention, since the semiconductor film on the back surface side of the semiconductor substrate is removed and the heat treatment is performed in the state where the insulating film exists on the back surface side of the semiconductor substrate, the high temperature heat treatment is performed. Even in this case, it is possible to prevent the semiconductor constituent atoms from sublimating from the back side of the semiconductor substrate. For this reason, according to the present invention, it is possible to prevent the semiconductor constituent atoms from adhering to the temperature sensor or the like, and it is possible to manufacture the semiconductor device without performing frequent maintenance. Therefore, according to the present invention, a semiconductor device can be manufactured with high manufacturing efficiency.

  In addition, according to the present invention, scrub cleaning is performed after removing the semiconductor film on the back surface side of the semiconductor substrate and before immersing in the cleaning liquid, so that a certain number of particles can be removed in scrub cleaning. For this reason, according to this invention, when a semiconductor substrate is immersed in cleaning liquid, the particle mixed in cleaning liquid can be restrained few. Therefore, according to the present invention, the number of particles reattached to the surface of a semiconductor film or the like can be extremely reduced, and as a result, the manufacturing yield of the semiconductor device can be improved.

  In addition, according to the present invention, since the heat treatment is performed in a state where the insulating film exists on the back surface side of the semiconductor substrate, the semiconductor constituent atoms are formed from the back surface side of the semiconductor substrate even when the high temperature heat treatment is performed. Sublimation can be prevented. For this reason, according to the present invention, it is possible to prevent the semiconductor constituent atoms from adhering to the temperature sensor or the like, and it is possible to manufacture the semiconductor device without performing frequent maintenance. Therefore, according to the present invention, a semiconductor device can be manufactured with high manufacturing efficiency.

  In addition, according to the present invention, since the high-temperature heat treatment is performed in the state where the insulating film exists on the back surface side of the semiconductor substrate for inspection, the semiconductor constituent atoms are sublimated from the back surface side of the semiconductor substrate for inspection. Silicon can be prevented from adhering to a sensor or the like. Therefore, according to the present invention, frequent maintenance is unnecessary, and inspection efficiency and manufacturing efficiency can be improved.

It is process sectional drawing (the 1) which shows the manufacturing method of the semiconductor device by 1st Embodiment of this invention. FIG. 9 is a process cross-sectional view (part 2) illustrating the method for manufacturing the semiconductor device according to the first embodiment of the invention; It is process sectional drawing (the 3) which shows the manufacturing method of the semiconductor device by 1st Embodiment of this invention. FIG. 9 is a process cross-sectional view (No. 4) illustrating the method for manufacturing the semiconductor device according to the first embodiment of the invention; It is process sectional drawing (the 5) which shows the manufacturing method of the semiconductor device by 1st Embodiment of this invention. It is process sectional drawing (the 6) which shows the manufacturing method of the semiconductor device by 1st Embodiment of this invention. It is process sectional drawing in the case of manufacturing a semiconductor device, without removing the polysilicon film of the back surface side of a silicon substrate. It is process sectional drawing (the 1) which shows the manufacturing method of the semiconductor device by 2nd Embodiment of this invention. It is process sectional drawing (the 2) which shows the manufacturing method of the semiconductor device by 2nd Embodiment of this invention. It is process sectional drawing (the 1) which shows the management method of the semiconductor manufacturing process by 3rd Embodiment of this invention. It is process sectional drawing (the 2) which shows the management method of the semiconductor manufacturing process by 3rd Embodiment of this invention.

[First Embodiment]
Recently, when forming an element isolation region by an STI (Shallow Trench Isolation) method, a silicon nitride film is patterned using a mask made of polysilicon, and a silicon substrate is etched using the patterned silicon nitride film as a mask. Thus, a technique for forming a trench, that is, a groove in a silicon substrate has been proposed. However, since the polysilicon film is formed not only on the surface side of the silicon substrate, that is, on the upper surface side, but also on the back surface side, that is, on the lower surface side, if hydrogen annealing is simply performed on such a silicon substrate, Silicon sublimes from the polysilicon film on the back side, and adheres to a temperature sensor or the like. When silicon adheres to a temperature sensor or the like, as described above, the measurement accuracy of the sensor is lowered, and thus the process controllability is lowered. In order to ensure process controllability, as described above, the semiconductor manufacturing apparatus must be frequently maintained, leading to a reduction in manufacturing efficiency.

  As a result of intensive studies, the inventors of the present application have conceived that the sublimation of silicon from the back surface side of the silicon substrate can be prevented as follows.

  A method of manufacturing a semiconductor device according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 6 are process cross-sectional views illustrating the semiconductor device manufacturing method according to the present embodiment.

  First, as shown in FIG. 1A, a silicon substrate 10 having a silicon oxide film 12 formed on the back side, that is, the bottom side is prepared.

  An example of such a substrate is an epitaxial substrate. The epitaxial substrate is a substrate in which a single crystal silicon layer is epitaxially grown on the surface side, that is, the upper surface side of the silicon substrate. In an epitaxial substrate, a silicon oxide film is generally formed on the back side. The reason why the silicon oxide film is formed on the back side of the epitaxial substrate is as follows. That is, the silicon substrate is doped with impurities such as boron, and when a single crystal silicon layer is simply grown on the silicon substrate, the impurities escape from the back side of the silicon substrate to the outside of the silicon substrate. Then, impurities are mixed in the film formation atmosphere and eventually mixed in the single crystal silicon layer. In order to form a single crystal silicon layer that does not contain impurities, it is necessary to prevent impurities from escaping from the back side of the silicon substrate to the outside of the silicon substrate. In the epitaxial substrate, a silicon oxide film is formed on the back side of the silicon substrate in order to prevent impurities from escaping from the back side of the silicon substrate to the outside of the silicon substrate.

  In the case of an epitaxial substrate in which no silicon oxide film is formed on the back surface side, when using a general silicon substrate that is not an epitaxial substrate, or when using an SOI (Silicon On Insulator) substrate, the back surface is formed as follows. A silicon substrate 10 having a silicon oxide film 12 formed on the side is obtained.

  That is, as shown in FIG. 6A, first, a silicon substrate 10 is prepared.

  Next, as shown in FIG. 6B, the silicon oxide film 12 is formed by, eg, thermal oxidation. The silicon oxide film 12 is formed so as to cover the entire surface of the silicon substrate 10. The film thickness of the silicon oxide film 12 is about 100 nm, for example.

  Here, the case where the silicon oxide film 12 is formed by the thermal oxidation method has been described as an example, but the method of forming the silicon oxide film 12 is not limited to the thermal oxidation method. For example, the silicon oxide film 12 may be formed by a CVD method or the like.

Next, only the silicon oxide film 12 on the surface side, that is, the upper surface side of the silicon substrate 10 is removed as follows. That is, hydrofluoric acid is supplied to the surface side of the silicon substrate 10 while rotating the silicon substrate 10. At this time, the N ₂ gas is sprayed on the back surface side of the silicon substrate 10 to prevent hydrofluoric acid from flowing into the back surface side of the silicon substrate 10. Thus, only the silicon oxide film 12 on the surface side of the silicon substrate 10 is removed. Thereafter, the silicon substrate 10 is rinsed with pure water, and then the silicon substrate 10 is dried. Thus, the silicon substrate 10 having the silicon oxide film 12 formed only on the back surface side is obtained (see FIG. 6C).

  Here, after the silicon oxide film 12 is formed on the front surface side and the back surface side of the silicon substrate 10, the silicon oxide film 12 on the front surface side is removed to remove the silicon oxide film 12 formed only on the back surface side. Although the substrate 10 is obtained, the silicon oxide film 12 may be formed only on the back side of the silicon substrate 10. When forming the silicon oxide film 12 only on the back side of the silicon substrate 10, for example, a CVD method can be used. The film thickness of the silicon oxide film 12 is about 10 nm, for example.

  Next, as shown in FIG. 1B, a silicon oxide film 14 is formed on the entire surface of the silicon substrate 10 by, eg, thermal oxidation. The film thickness of the silicon oxide film 14 is about 10 nm, for example. The silicon oxide film 14 functions as a buffer film for relieving stress between the silicon nitride film 16 and the silicon substrate 10.

  Next, the silicon nitride film 16 is formed by, eg, CVD. The silicon oxide film 16 is formed so as to cover the entire surface. The film thickness of the silicon nitride film 16 is about 100 nm, for example. The silicon nitride film 16 functions as a stopper film when the silicon oxide film 26 (see FIG. 3C) is polished in a later step.

  Next, a polysilicon film 18 is formed on the silicon nitride film 16 by, eg, CVD. The polysilicon film 18 is formed so as to cover the entire surface. The thickness of the polysilicon film 18 is, for example, 150 nm. The polysilicon film 18 functions as a mask when the silicon nitride film 16 is patterned.

Next, the polysilicon film 18 on the back surface side of the silicon substrate 10 is removed as follows. That is, first, the front side and the back side of the silicon substrate 10 are reversed. Thereby, the back surface side of the silicon substrate 10 is positioned on the upper surface side, and the back surface side of the silicon substrate 10 is positioned on the lower surface side. Next, hydrofluoric acid is supplied to the upper surface side of the silicon substrate 10, that is, the back surface side of the silicon substrate 10 while rotating the silicon substrate 10. As the hydrofluoric acid, for example, hydrofluoric acid formed by mixing a 50% concentration hydrofluoric acid aqueous solution and a 60% nitric acid aqueous solution in a ratio of 1:50 to 1: 300 is used. At this time, the N ₂ gas is sprayed on the lower surface side, that is, the front surface side of the silicon substrate 10, thereby preventing the hydrofluoric acid from flowing into the lower surface side, that is, the front surface side of the silicon substrate 10. Thus, the polysilicon film 18 on the back side of the silicon substrate 10 is removed. Thereafter, the silicon substrate 10 is rinsed with pure water, and then the silicon substrate 10 is dried. On the back side of the silicon substrate 10, the surface of the silicon nitride film 16 is exposed. Particles 19 generated when removing the polysilicon film 18 are attached to the exposed surface of the silicon nitride film 16.

  Next, as shown in FIG. 2A, the particles 19 are removed by scrub cleaning. Among the many particles 19 generated when removing the polysilicon 18, a certain number of particles 19 are removed by this scrub cleaning. However, not all particles 19 are removed by this scrub cleaning, and a certain number of particles 19 remain on the surface of the silicon substrate 16 or the like. As a cleaning liquid used for scrub cleaning, for example, APM (Ammonia-Hydrogen Peroxide Mixture) can be used. APM is a cleaning liquid in which ammonia, hydrogen peroxide, and water are mixed. The cleaning liquid used for scrub cleaning is not limited to APM, and may be pure water, for example. However, more particles 19 can be removed when APM is used than when pure water is used.

  Next, the particles 19 remaining on the surface of the silicon nitride film 16 and the like are removed by immersing the silicon substrate 10 in a cleaning solution (see FIG. 2B). For example, APM is used as the cleaning liquid. As a result, the particles 19 remaining on the surface of the silicon nitride film 16 and the like are removed. Since many particles have already been removed during scrub cleaning, the number of particles 19 removed by immersing the silicon substrate 10 in the cleaning liquid is not very large. For this reason, the number of particles 19 mixed in the cleaning liquid can be reduced. Since the number of particles 19 mixed in the cleaning liquid can be reduced, it is possible to prevent the particles 19 from reattaching to the surface of the silicon nitride film 16 or the polysilicon film 18.

  Next, a photoresist film 20 is formed on the polysilicon film 18 by, eg, spin coating.

  Next, an opening 22 is formed in the photoresist film 20 using a photolithography technique (see FIG. 2C).

Next, the polysilicon film 18 is anisotropically etched using the photoresist film 20 as a mask. As the etching gas, for example, a mixed gas of HBr and O ₂ is used.

  Next, as shown in FIG. 3A, the silicon nitride film 16 and the silicon oxide film 14 are anisotropically etched using the polysilicon film 18 as a mask. For example, fluorocarbon is used as the etching gas.

Next, as shown in FIG. 3B, the silicon substrate 10 is etched using the silicon nitride film 16 as a mask. As the etching gas, for example, a mixed gas of HBr and O ₂ can be used. Thereby, a trench 24, that is, a groove is formed in the silicon substrate 10. When the trench 24 is formed, the polysilicon film 18 on the silicon nitride film 16 is also removed at the same time.

  Next, as shown in FIG. 3C, a silicon oxide film 26 is formed by, for example, a high density plasma (HDP) CVD method. The film thickness of the silicon oxide film 26 is, for example, 500 nm.

  Next, as shown in FIG. 4A, the silicon oxide film 26 is polished by, eg, CMP until the surface of the silicon nitride film 16 is exposed. Thus, the silicon oxide film 26 is buried in the trench 24.

  Next, as shown in FIG. 4B, the silicon nitride film 16 is removed by etching using phosphoric acid, for example.

  Next, the silicon oxide film 14 is removed by etching using, for example, hydrofluoric acid. At this time, it is necessary to prevent the silicon oxide film 12 formed on the back surface side of the silicon substrate 10 and the silicon oxide film 26 embedded in the trench 24 from being greatly etched. For example, the silicon oxide film 14 may be etched in an extremely short etching time. Thus, the element isolation region 28 made of the silicon oxide film 26 is formed by the STI method. The element region 30 is defined by the element isolation region 28.

  Next, an n-type well 32 and a p-type well 34 are formed by appropriately introducing dopant impurities into the element region 30 by, for example, ion implantation (see FIG. 4C).

  Next, as shown in FIG. 5A, as a pretreatment for the step of forming the gate insulating film 36 (see FIG. 5B), hydrogen annealing, that is, heat treatment in an atmosphere containing hydrogen is performed. . The annealing temperature is about 1000 ° C., for example. When performing the hydrogen annealing, the heat treatment is performed in a state where the silicon oxide film 12 exists on the back surface side of the silicon substrate 10. This is because sublimation of silicon can be prevented if hydrogen annealing is performed in a state where the silicon oxide film 12 is present on the back side of the silicon substrate 10. If the silicon oxide film is present at least 1 nm or more on the back surface side of the silicon substrate 12, sublimation of silicon from the back surface side of the silicon substrate 10 can be prevented, and silicon can be prevented from adhering to the temperature sensor or the like. be able to.

  During the hydrogen annealing, the surface of the silicon oxide film 12 may be slightly reduced by hydrogen, and the silicon oxide film 12 may be slightly thin. Although the thickness of the thin film varies depending on the method of forming the silicon oxide film 12 or the like, the thinned thickness is as small as about 1 nm, for example. If a silicon oxide film 12 of 2 nm or more, for example, is present on the back side of the silicon substrate 10 at the stage of starting the hydrogen annealing, the thickness of the silicon oxide film 12 is reduced by, for example, 1 nm due to reduction of the silicon oxide film 12 by hydrogen. Even so, the silicon oxide film 12 of 1 nm or more remains at the stage where the hydrogen annealing is completed. If the silicon oxide film 12 having a thickness of 1 nm or more exists on the back surface side of the silicon substrate 10, it is possible to sufficiently prevent sublimation of silicon from the back surface side of the silicon substrate 10. In the present embodiment, the silicon oxide film 12 is formed to be sufficiently thick, for example, 100 nm. When the silicon oxide film 14 is etched, the etching is performed for a short time so that the silicon oxide film 12 is not largely etched. To do. Therefore, the silicon oxide film 12 exists with a sufficient thickness on the back side of the silicon substrate 10. Accordingly, sublimation of silicon from the back surface side of the silicon substrate 10 can be reliably prevented.

  Next, as shown in FIG. 5B, a gate insulating film 36 having a thickness of 1.2 nm is formed by, eg, thermal oxidation.

  Thereafter, a gate electrode (not shown), a source / drain diffusion layer (not shown), and the like are appropriately formed.

  Thus, the semiconductor device according to the present embodiment is manufactured.

  The semiconductor device manufacturing method according to the present embodiment removes the polysilicon film 18 on the back surface side, that is, the bottom surface side of the silicon substrate 10, and heat-treats in a state where the silicon oxide film 12 exists on the back surface side of the silicon substrate 10. There is one of the main features in doing.

  When hydrogen annealing is performed in a state where the polysilicon film 18 exists on the back surface side of the silicon substrate 10, as described above, silicon is sublimated from the back surface side of the silicon substrate 10, and the silicon substrate 10 is placed. Silicon adheres to a temperature sensor or the like provided below the portion to be applied. When silicon adheres to the temperature sensor, as described above, the measurement accuracy of the sensor is lowered, and thus the process controllability is lowered. In order to ensure process controllability, the semiconductor manufacturing apparatus must be frequently maintained, leading to a reduction in manufacturing efficiency.

  On the other hand, in the present embodiment, the polysilicon film 18 on the back surface side of the silicon substrate 10 is removed, and the heat treatment is performed in a state where the silicon oxide film 12 is present on the back surface side of the silicon substrate 10. Even when annealing is performed, it is possible to prevent silicon from sublimating from the back side of the silicon substrate 10. Therefore, according to this embodiment, it is possible to prevent silicon from adhering to the temperature sensor or the like, and it is possible to manufacture a semiconductor device without performing frequent maintenance. Therefore, according to the present embodiment, a semiconductor device can be manufactured with high manufacturing efficiency.

As described above, Patent Document 1 discloses that when a semiconductor wafer is heat-treated, an O ₂ gas is supplied to the back side of the semiconductor wafer, and an oxide film is formed on the back side of the semiconductor wafer. A technique for preventing silicon from sublimating from the back side of the substrate is disclosed. However, in the technique disclosed in Patent Document 1, O ₂ gas flows around the surface side of the semiconductor wafer, and an undesired oxide film is generated on the surface side of the semiconductor wafer. At this time, since the film thickness of the oxide film generated on the surface side of the semiconductor wafer is not stable, it becomes extremely difficult to control the film thickness of the gate insulating film to be formed to a desired film thickness. On the other hand, the semiconductor device manufacturing method according to the present embodiment does not generate an undesired silicon oxide film on the surface side of the silicon substrate, and can form a gate insulating film with a desired film thickness. Thus, it is extremely advantageous as compared with the technique disclosed in Patent Document 1.

  Further, according to this embodiment, since the polysilicon film 18 on the back surface side of the silicon substrate 10 is removed, it is possible to prevent the end portion of the polysilicon film 18 from becoming particles as described below. it can.

  FIG. 7 is a process cross-sectional view in the case of manufacturing a semiconductor device without removing the polysilicon film on the back side of the silicon substrate.

  When the silicon nitride film 16 is removed by etching without removing the polysilicon film 18 on the back surface side of the silicon substrate 10 (see FIG. 7A), the end of the polysilicon film 18 extends from the end of the silicon nitride film 16. It will be overhanging. As a result, the end of the polysilicon film 18 may be separated, and the separated end of the polysilicon film 18 may become particles.

  In this embodiment, since the polysilicon film 18 on the back surface side of the silicon substrate 10 is removed, it is possible to prevent the end portion of the polysilicon film 18 from separating into particles. For this reason, according to this embodiment, it can contribute to the improvement of the manufacturing yield of a semiconductor device.

  The semiconductor device manufacturing method according to the present embodiment also includes scrub cleaning after removing the polysilicon film 18 on the back surface side of the silicon substrate 10 and before immersing the silicon substrate 10 in a cleaning solution. There is one.

  When the particles 19 are removed by immediately immersing in the cleaning liquid after removing the polysilicon film 18, a large number of particles 19 are mixed in the cleaning liquid. The particles 19 mixed in the cleaning liquid may reattach to the surface of the polysilicon film 18, the silicon nitride film 16, and the like. As the number of particles 19 mixed in the cleaning liquid increases, the number of particles 19 that re-adhere to the surface of the polysilicon film 18 or the silicon nitride film 16 tends to increase. The reattached particles 19 cause a reduction in the manufacturing yield of the semiconductor device.

  On the other hand, in this embodiment, since the scrub cleaning is performed after removing the polysilicon film 18 on the back surface side of the silicon substrate 10 and before immersing in the cleaning liquid, a certain number of particles 19 are removed in the scrub cleaning. be able to. For this reason, according to this embodiment, when the silicon substrate 10 is immersed in the cleaning liquid, it is possible to reduce the number of particles 19 mixed in the cleaning liquid. Therefore, according to the present embodiment, the number of particles 19 that re-adhere to the surface of the polysilicon film 18, the silicon nitride film 16, etc. can be extremely reduced, and the manufacturing yield of the semiconductor device can be improved.

[Second Embodiment]
A method for fabricating a semiconductor device according to the second embodiment of the present invention will be described with reference to FIGS. 8 and 9 are process cross-sectional views illustrating the semiconductor device manufacturing method according to the present embodiment. The same components as those of the semiconductor device manufacturing method according to the first embodiment shown in FIGS. 1 to 7 are denoted by the same reference numerals, and description thereof will be omitted or simplified.

  In the method of manufacturing the semiconductor device according to the present embodiment, a mask made of a polysilicon film is not formed when the element isolation region 28 is formed by the STI method, but the silicon oxide film 12 exists on the back side of the silicon substrate 10. The main feature is to perform hydrogen annealing in the state.

  First, as shown in FIG. 8A, first, a silicon substrate 10 is prepared. As the silicon substrate 10, for example, a silicon substrate formed by the CZ method is used.

  Next, as shown in FIG. 8B, a silicon oxide film 12 is formed on the entire surface of the silicon substrate 12 by, eg, thermal oxidation. The film thickness of the silicon oxide film 12 is about 100 nm, for example.

  Next, only the silicon oxide film 12 on the surface side of the silicon substrate 10 is removed using, for example, hydrofluoric acid. Thus, the silicon substrate 10 having the silicon oxide film 12 formed only on the back surface side is obtained (see FIG. 8C).

  Here, after the silicon oxide film 12 is formed on the front surface side and the back surface side of the silicon substrate 10, the silicon oxide film 12 on the front surface side is removed to remove the silicon oxide film 12 formed only on the back surface side. Although the substrate 10 is obtained, the silicon oxide film 12 may be formed only on the back side of the silicon substrate 10. When forming the silicon oxide film 12 only on the back side of the silicon substrate 10, for example, a CVD method can be used. The film thickness of the silicon oxide film 12 is about 10 nm, for example.

  Here, a general silicon substrate formed by the CZ method is used as the silicon substrate 10, but the silicon substrate 10 is not limited to a general silicon substrate formed by the CZ method. An SOI substrate may be used.

  Next, as shown in FIG. 9A, a silicon oxide film 14 and a silicon nitride film 16 are sequentially formed. The method for forming the silicon oxide film 14 and the method for forming the silicon nitride film 16 may be the same as the method for manufacturing the semiconductor device described above with reference to FIG.

  Next, as shown in FIG. 9B, a photoresist film 20 is formed on the silicon nitride film 16 by, eg, spin coating.

  Next, an opening 22 is formed in the photoresist film 20 using a photolithography technique.

  Next, the silicon nitride film 16 and the silicon oxide film 14 are anisotropically etched using the photoresist film 20 as a mask. For example, fluorocarbon is used as the etching gas.

Next, as shown in FIG. 9C, the silicon substrate 10 is etched using the silicon nitride film 16 as a mask. As the etching gas, for example, a mixed gas of HBr and O ₂ is used. Thus, the trench 24 is formed in the silicon substrate 10.

  The subsequent manufacturing method of the semiconductor device is the same as the manufacturing method of the semiconductor device described above with reference to FIGS.

  Thus, the semiconductor device according to the present embodiment is manufactured.

  In the semiconductor device according to the present embodiment, as described above, the mask made of the polysilicon film is not formed when the element isolation region 28 is formed by the STI method, but the silicon oxide film 12 is formed on the back surface side of the silicon substrate 10. The main feature is that the hydrogen annealing is performed in a state where

  According to the present embodiment, since the heat treatment is performed in the state where the silicon oxide film 12 exists on the back surface side of the silicon substrate 10, silicon is sublimated from the back surface side of the silicon substrate 10 during the hydrogen annealing as described above. Can be prevented. According to the present embodiment, since silicon can be prevented from adhering to a temperature sensor or the like, process controllability can be ensured without requiring frequent maintenance of the semiconductor manufacturing apparatus. Therefore, according to this embodiment, a semiconductor device can be manufactured with high manufacturing efficiency.

  When an epitaxial substrate is used, since a silicon oxide film is generally formed on the back side of the epitaxial substrate, silicon is not sublimated from the silicon substrate when hydrogen annealing is performed. However, since the epitaxial substrate is expensive, it is advantageous to use a general silicon substrate that is not an epitaxial substrate in order to reduce the cost. In this embodiment, even when an inexpensive general silicon substrate is used, it is possible to prevent the silicon from sublimating from the back side of the silicon substrate during the hydrogen annealing. It is possible to contribute to cost reduction.

[Third Embodiment]
A semiconductor manufacturing process management method according to a third embodiment of the present invention will be described with reference to FIGS. 10 and 11 are process cross-sectional views illustrating the semiconductor manufacturing process management method according to the present embodiment. The same components as those in the method of manufacturing the semiconductor device according to the first or second embodiment shown in FIGS. 1 to 9 are denoted by the same reference numerals, and description thereof is omitted or simplified.

  In the semiconductor manufacturing process management method according to the present embodiment, hydrogen annealing is performed in a state where the silicon oxide film 12 is present on the back side of the silicon substrate 10a for inspection, and then a gate insulating film 36 is formed to form gate insulation. The main feature is to manage the manufacturing process by inspecting the film 36 and taking appropriate measures according to the inspection result.

  First, as shown in FIG. 10A, an inspection silicon substrate 10a is prepared. As the inspection silicon substrate 10a, for example, a silicon substrate formed by the CZ method is used.

  Next, as shown in FIG. 10B, a silicon oxide film 12 is formed on the entire surface of the inspection silicon substrate 10a by, eg, thermal oxidation. The film thickness of the silicon oxide film 12 is about 100 nm, for example.

  Next, only the silicon oxide film 12 on the surface side of the silicon substrate 10a for inspection is removed using, for example, hydrofluoric acid. Thus, an inspection silicon substrate 10a having the silicon oxide film 12 formed only on the back surface side is obtained (see FIG. 10C).

  Here, after the silicon oxide film 12 is formed on the front surface side and the back surface side of the silicon substrate 10a for inspection, the silicon oxide film 12 on the front surface side is removed to form the silicon oxide film 12 only on the back surface side. The obtained silicon substrate 10a for inspection is obtained, but the silicon oxide film 12 may be formed only on the back side of the silicon substrate 10a for inspection. When forming the silicon oxide film 12 only on the back side of the silicon substrate 10, for example, a CVD method can be used. The film thickness of the silicon oxide film 12 is about 10 nm, for example.

  Here, a general silicon substrate formed by the CZ method is used as the inspection silicon substrate 10a. However, the inspection silicon substrate 10a is limited to a general silicon substrate formed by the CZ method. For example, an SOI substrate may be used.

  Next, hydrogen annealing is performed as a pretreatment for the step of forming the gate insulating film 36 (see FIG. 11). The annealing temperature is about 1000 ° C., for example. When performing the hydrogen annealing, the annealing is performed in a state where the silicon oxide film 12 is present on the back side of the silicon substrate 10a for inspection. If hydrogen annealing is performed in a state where the silicon oxide film 12 is present on the back side of the inspection silicon substrate 10a, as described above, silicon sublimation from the back side of the inspection silicon substrate 10a can be prevented. It is possible to prevent silicon from adhering to the temperature sensor or the like. The silicon oxide film 12 only needs to be present at, for example, 1 nm or more on the back side of the silicon substrate 10 for inspection.

  Next, a gate insulating film 36 having a thickness of 1.2 nm is formed by, eg, thermal oxidation.

  Next, the gate insulating film 36 is inspected. As an inspection item, the film thickness of the gate insulating film 36 is mentioned, for example.

  As a result of the inspection of the gate insulating film 36a, for example, when the gate insulating film 36a having a desired film thickness is formed, it is determined that there is no particular problem in the semiconductor manufacturing apparatus or the like, and the semiconductor device is actually manufactured. A gate insulating film 36 is formed on the silicon substrate 10 for the purpose (see FIG. 5B).

  On the other hand, if the gate insulating film 36a having a desired film thickness is not formed as a result of the inspection of the gate insulating film 36a, it is considered that there is some problem in the semiconductor manufacturing apparatus or the like. In this case, appropriate measures are taken, for example, maintenance of the semiconductor manufacturing apparatus is performed. When the desired gate insulating film 36a can be formed, the gate insulating film 36 is formed on the silicon substrate 10 for actually manufacturing the semiconductor device (see FIG. 5B). .

  In the semiconductor manufacturing process management method according to the present embodiment, as described above, hydrogen annealing is performed in a state where the silicon oxide film 12 is present on the back side of the silicon substrate 10a for inspection, and then the gate insulating film 36a is formed. The main feature is that the gate insulating film 36a is formed and inspected, and a measure corresponding to the inspection result is taken.

  According to the present embodiment, hydrogen annealing is performed in a state where the silicon oxide film 12 is present on the back surface side of the inspection silicon substrate 10a, and therefore the back surface side of the inspection silicon substrate 10a is the same as in the above embodiment. It is possible to prevent silicon from sublimating and adhering to the temperature sensor or the like. Therefore, also according to the present embodiment, frequent maintenance is unnecessary, and inspection efficiency and manufacturing efficiency can be improved.

  When an epitaxial substrate is used, since a silicon oxide film is generally formed on the back side of the epitaxial substrate, silicon is not sublimated from the silicon substrate when hydrogen annealing is performed. However, epitaxial substrates are too expensive to use as test substrates. In this embodiment, even when an inexpensive general silicon substrate is used, it is possible to prevent silicon from sublimating from the back side of the silicon substrate during hydrogen annealing. This is extremely advantageous as compared with the case of using a substrate.

[Modified Embodiment]
The present invention is not limited to the above embodiment, and various modifications can be made.

  For example, in the first embodiment, the polysilicon film 18 is used as a mask, but the material of the mask is not limited to polysilicon. For example, any silicon film such as an amorphous silicon film can be used. Further, the material of the mask is not limited to silicon, and any semiconductor can be used. For example, as the mask material, a semiconductor having substantially the same etching characteristics as the semiconductor substrate material can be used. If a semiconductor material having substantially the same etching characteristics as the material of the semiconductor substrate is used, when the trench is formed in the semiconductor substrate using the insulating film as a mask, the mask made of the semiconductor formed on the insulating film is simultaneously removed. Is possible.

  In the above embodiment, the case where a silicon substrate is used as the substrate has been described as an example. However, the present invention is not limited to the case where a silicon substrate is used, and can be applied to the case where any semiconductor substrate is used. is there.

  Moreover, in the said embodiment, although the silicon oxide film 12 was formed in the back surface side of the silicon substrates 10 and 10a, the insulating film formed in the back surface side of the silicon substrates 10 and 10a is not limited to a silicon oxide film. Any film can be used as appropriate as long as it can prevent sublimation of semiconductor constituent atoms from the back side of the semiconductor substrate during annealing.

(Supplementary Note 1) A method for manufacturing a semiconductor device including a step of forming a gate insulating film on a semiconductor substrate,
Before the step of forming the gate insulating film, a step of forming an insulating film so as to cover a front surface side and a back surface side of the semiconductor substrate, and a step of etching away the insulating film on the front surface side of the semiconductor substrate; And a step of heat-treating the semiconductor substrate in a state in which the insulating film is present on the back surface side of the semiconductor substrate.

(Additional remark 2) In the manufacturing method of the semiconductor device of Additional remark 1,
In the step of heat-treating the semiconductor substrate, the semiconductor substrate is heat-treated in an atmosphere containing hydrogen.

(Appendix 3) A method for managing a semiconductor manufacturing process, comprising: a step of forming a gate insulating film on a semiconductor substrate for inspection; and a step of inspecting the gate insulating film,
Before the step of forming the gate insulating film, a step of forming an insulating film so as to cover the front surface side and the back surface side of the semiconductor substrate for inspection, and the insulating film on the front surface side of the semiconductor substrate for inspection And a step of heat-treating the semiconductor substrate in a state where the insulating film is present on the back side of the semiconductor substrate for inspection. .

(Additional remark 4) It is the management method of the semiconductor manufacturing process which has the process of forming a gate insulating film in the semiconductor substrate for a test | inspection, and the process of test | inspecting the said gate insulating film,
Before the step of forming the gate insulating film, a step of forming an insulating film on the back side of the semiconductor substrate for inspection, and the state where the insulating film exists on the back side of the semiconductor substrate for inspection And a step of heat treating the semiconductor substrate. A method of managing a semiconductor manufacturing process, comprising:

(Additional remark 5) In the management method of the semiconductor manufacturing process of Additional remark 3 or 4,
In the step of heat-treating the semiconductor substrate, the semiconductor substrate is heat-treated in an atmosphere containing hydrogen.

(Additional remark 6) The process of forming a 2nd insulating film so that the surface side of the semiconductor substrate in which the 1st insulating film was formed in the back surface side, and the said back surface side may be covered,
Forming a semiconductor film so as to cover the second insulating film on the front surface side and the back surface side;
Etching the semiconductor film on the back side; and
And a step of heat-treating the semiconductor substrate in a state in which the second insulating film is present on the back surface side of the semiconductor substrate.

(Appendix 7) A step of forming a first insulating film so as to cover the front surface side and the back surface side of a semiconductor substrate;
Etching and removing the first insulating film on the surface side of the semiconductor substrate;
Forming a second insulating film so as to cover the front surface side and the back surface side of the semiconductor substrate;
Forming a semiconductor film so as to cover the second insulating film on the front surface side and the back surface side;
Etching the semiconductor film on the back side; and
And a step of heat-treating the semiconductor substrate in a state in which the second insulating film is present on the back surface side of the semiconductor substrate.

(Appendix 8) In the method for manufacturing a semiconductor device according to Appendix 6 or 7,
The method of manufacturing a semiconductor device, further comprising a step of immersing the semiconductor substrate in a cleaning solution after the step of etching away the semiconductor film on the back surface side and before the step of heat-treating the semiconductor substrate.

(Supplementary note 9) In the method for manufacturing a semiconductor device according to supplementary note 8,
After the step of etching away the semiconductor film on the back surface side and before the step of immersing the semiconductor substrate in a cleaning solution, the semiconductor device further comprises a step of scrub cleaning the back surface side of the semiconductor substrate. Manufacturing method.

(Additional remark 10) In the manufacturing method of the semiconductor device of Additional remark 9,
In the scrub cleaning step, the back surface side of the semiconductor substrate is scrub cleaned using a first cleaning liquid and a brush in which ammonia, hydrogen peroxide, and water are mixed. Production method.

(Supplementary note 11) In the method for manufacturing a semiconductor device according to any one of supplementary notes 8 to 10,
In the step of immersing the semiconductor substrate in a cleaning solution, the semiconductor substrate is immersed in a second cleaning solution obtained by mixing ammonia, hydrogen peroxide, and water.

(Supplementary Note 12) In the method for manufacturing a semiconductor device according to any one of Supplementary Notes 6 to 11,
After the step of removing the semiconductor film on the back side and before the step of heat-treating the semiconductor substrate, forming an opening reaching the second insulating film in the semiconductor film on the front side; and Etching the second insulating film using the semiconductor film as a mask; etching the semiconductor substrate using the second insulating film as a mask to form a groove in the semiconductor substrate; and a third in the groove. And a step of forming an element isolation region by embedding the insulating film.

(Additional remark 13) In the manufacturing method of the semiconductor device of Additional remark 12,
In the step of heat-treating the semiconductor substrate, the semiconductor substrate is heat-treated in an atmosphere containing hydrogen,
The method of manufacturing a semiconductor device, further comprising a step of forming a gate insulating film on the semiconductor substrate after the step of heat-treating the semiconductor substrate.

DESCRIPTION OF SYMBOLS 10 ... Silicon substrate 10a ... Silicon substrate 12 for inspection ... Silicon oxide film 14 ... Silicon oxide film 16 ... Silicon nitride film 18 ... Polysilicon film 19 ... Particle 20 ... Photoresist film 22 ... Opening 24 ... Trench 26 ... Silicon oxide Film 28 ... element isolation region 30 ... element region 32 ... n-type well 34 ... p-type well 36, 36a ... gate insulating film

Claims (9)

A method of manufacturing a semiconductor device including a step of forming a gate insulating film on a semiconductor substrate,
Before the step of forming the gate insulating film, a step of forming an insulating film so as to cover a front surface side and a back surface side of the semiconductor substrate, and a step of etching away the insulating film on the front surface side of the semiconductor substrate; And a step of heat-treating the semiconductor substrate in a state in which the insulating film is present on the back surface side of the semiconductor substrate. A method for managing a semiconductor manufacturing process, comprising: a step of forming a gate insulating film on a semiconductor substrate for inspection; and a step of inspecting the gate insulating film,
Before the step of forming the gate insulating film, a step of forming an insulating film so as to cover the front surface side and the back surface side of the semiconductor substrate for inspection, and the insulating film on the front surface side of the semiconductor substrate for inspection And a step of heat-treating the semiconductor substrate in a state where the insulating film is present on the back side of the semiconductor substrate for inspection. . A method for managing a semiconductor manufacturing process, comprising: a step of forming a gate insulating film on a semiconductor substrate for inspection; and a step of inspecting the gate insulating film,
Before the step of forming the gate insulating film, a step of forming an insulating film on the back side of the semiconductor substrate for inspection, and the state where the insulating film exists on the back side of the semiconductor substrate for inspection And a step of heat treating the semiconductor substrate. A method of managing a semiconductor manufacturing process, comprising: Forming a second insulating film so as to cover the front surface side of the semiconductor substrate having the first insulating film formed on the back surface side and the back surface side;
Forming a semiconductor film so as to cover the second insulating film on the front surface side and the back surface side;
Etching the semiconductor film on the back side; and
And a step of heat-treating the semiconductor substrate in a state in which the second insulating film is present on the back surface side of the semiconductor substrate. Forming a first insulating film so as to cover the front surface side and the back surface side of the semiconductor substrate;
Etching and removing the first insulating film on the surface side of the semiconductor substrate;
Forming a second insulating film so as to cover the front surface side and the back surface side of the semiconductor substrate;
Forming a semiconductor film so as to cover the second insulating film on the front surface side and the back surface side;
Etching the semiconductor film on the back side; and
And a step of heat-treating the semiconductor substrate in a state in which the second insulating film is present on the back surface side of the semiconductor substrate. In the manufacturing method of the semiconductor device according to claim 4 or 5,
The method of manufacturing a semiconductor device, further comprising a step of immersing the semiconductor substrate in a cleaning solution after the step of etching away the semiconductor film on the back surface side and before the step of heat-treating the semiconductor substrate. The method of manufacturing a semiconductor device according to claim 6.
After the step of etching away the semiconductor film on the back surface side and before the step of immersing the semiconductor substrate in a cleaning solution, the semiconductor device further comprises a step of scrub cleaning the back surface side of the semiconductor substrate. Manufacturing method. In the manufacturing method of the semiconductor device according to any one of claims 4 to 7,
After the step of removing the semiconductor film on the back side and before the step of heat-treating the semiconductor substrate, forming an opening reaching the second insulating film in the semiconductor film on the front side; and Etching the second insulating film using the semiconductor film as a mask; etching the semiconductor substrate using the second insulating film as a mask to form a groove in the semiconductor substrate; and a third in the groove. And a step of forming an element isolation region by embedding the insulating film. The method of manufacturing a semiconductor device according to claim 8.
In the step of heat-treating the semiconductor substrate, the semiconductor substrate is heat-treated in an atmosphere containing hydrogen,
The method of manufacturing a semiconductor device, further comprising a step of forming a gate insulating film on the semiconductor substrate after the step of heat-treating the semiconductor substrate.

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