JP2011171615A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device that does not require any dedicated device and decreases the number of processes. <P>SOLUTION: The method of manufacturing the semiconductor device in which at least one semiconductor device is formed on a wafer-like substrate includes a deposition step of forming a film of at least one layer on a wafer surface of the substrate using a deposition material corresponding thereto, and a film removing step of removing a film of a wafer part other than the wafer surface by supplying an etching gas matching the deposition material to a periphery of the wafer having been filmed while supplying an inert gas to the wafer surface having been filmed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a semiconductor element manufacturing method for manufacturing a semiconductor element by using a film forming technique or an etching technique, and more particularly to a semiconductor element manufacturing method for removing a film other than a wafer surface such as a wafer edge.

  FIG. 1 shows a typical wafer cross section on which semiconductor elements are formed. In the wafer, for example, a polysilicon film 13 is formed on a substrate 11, and a tungsten silicide film 14 (hereinafter referred to as WSi) is further formed thereon. Each of these layers is formed by, for example, the CVD method. As shown in the middle part of the figure, each layer 13 and the film 13 are uniformly formed not only on the wafer surface but also on the entire wafer surface, that is, on the front surface, the back surface, and the wafer edge portion (A portion). 14 will be formed. When a gate pattern is formed on the wafer in such a state by a method such as dry etching as a next process, a phenomenon that an unnecessary film remains in a part of the wafer edge portion (B portion) occurs.

  FIG. 2 shows a part of a micrograph obtained by photographing a cross section of the edge portion of the wafer as shown in FIG. Here, it is observed that a film made of WSi or polysilicon remains in a “throw away” shape at the wafer edge portion (B portion). It is inferred that such a “break” state is caused by the fact that the etching gas is incident on the wafer in the vertical direction when the gate is etched. If an attempt is made to process the next process in such a state, these films are peeled off and scattered on the wafer surface, resulting in a shape defect and a particle source, resulting in the generation of defective products and a decrease in yield in semiconductor element manufacturing. In addition, the inside of a process apparatus such as a chamber may be contaminated. Therefore, it is necessary to remove these unnecessary remaining films in advance.

  At present, well-known methods for removing the film at the wafer edge are roughly classified into a method for physically polishing the wafer edge and a method for removing the remaining film using a chemical reaction. As the former method, a CMP (Chemical Mechanical Polishing) method, a polishing tape method, and a scrubber method are known. The CMP method is a method in which only the wafer edge portion is polished by CMP. The polishing tape method uses a polishing tape instead of a CMP pad. The scrubber method is a method of physically removing the remaining film by rubbing a sponge. The latter method includes a dry etching method and a cleaning method. The dry etching method is a method of removing a remaining film only on the wafer edge with an etching gas. The cleaning method is a method in which a chemical solution is applied only to the wafer edge portion and cleaned to remove the remaining film. Further, as a method of dry etching organic substances attached to an edge portion such as a wafer, there is a technique disclosed in Patent Document 1.

JP 2002-352775 A

  These conventional methods have their merits and demerits in terms of film removal performance, cost required for implementation, and the like, and it is not usually possible to determine which method is optimal. However, the disadvantages common to all methods are that a dedicated apparatus is required to remove the film and that a process for removing the film is required in addition to the film forming process.

  An object of the present invention is to provide a method of manufacturing a semiconductor element that reduces the number of steps without requiring a dedicated device.

  A semiconductor device manufacturing method according to the present invention is a semiconductor device manufacturing method for manufacturing at least one semiconductor device on a wafer-like substrate, and at least one film is formed on the wafer surface of the substrate. A film forming step for forming the film, and an etching gas suitable for the film forming material is supplied around the wafer on which the film has been formed while supplying an inert gas to the wafer surface on which the film has been formed. And a film removal step of removing a film on a wafer portion other than the wafer surface.

  According to the semiconductor element manufacturing method of the present invention, the number of processes can be reduced without requiring a dedicated apparatus.

It is sectional drawing which shows the normal wafer cross section after film-forming. It is a figure which shows a part of microscope picture which image | photographed the edge cross section of the wafer. It is sectional drawing which shows the state of the wafer in the board | substrate preparation process of 1st Example of this invention. It is sectional drawing which shows the state of the wafer in a film-forming process. It is sectional drawing which shows the state of the wafer in a film | membrane removal process. It is sectional drawing which shows the state of the wafer in an element area | region formation process. It is a perspective view which shows the lower surface and peripheral edge part of a shower head. It is a figure which shows the utilization form of the chamber in a 1st Example. It is a figure which shows the utilization form of the chamber in a 2nd Example.

  Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  3 to 6 show the state of the wafer in each step of executing the semiconductor device manufacturing method according to the present invention in the first embodiment. Here, as an example, a case where a gate structure of a general transistor is formed is shown.

Referring to FIG. 3, first, in a substrate preparation step, a substrate 11 made of a material such as Si is prepared as a wafer 10 and the surface is clean. Next, an oxide film 12 is formed on the surface of the substrate 11 by a technique such as thermal oxidation. Form. Next, a polysilicon film 13 made of polycrystalline Si serving as a gate is formed thereon by a technique such as a CVD (Chemical Vapor Deposition) method. For example, in the CVD method, a plurality of wafers 10 are inserted into a core tube, and first, a thermal oxide film 12 is formed on the wafer surface by flowing hydrogen, oxygen, or the like while the wafer is heated. Next, the polysilicon film 13 is formed by flowing SiH ₄ -based gas while the wafer is heated. The polysilicon film 13 may be doped with impurities during the film formation, or may be doped with an implant technique after the film formation so as to have electrical conductivity.

Referring to FIG. 4, in the next film formation step, a metal film is formed on the formed polysilicon film 13 in order to reduce the resistance of the gate electrode. In this step, the wafer on which the polysilicon film 13 is formed is placed in a dedicated chamber (not shown) for each wafer. In this embodiment, tungsten is used as an example of the film forming material of the metal film, and a tungsten silicide film (hereinafter referred to as a WSi film) 14 is formed. The WSi film 14 is usually formed by a CVD method. Therefore, as shown in the figure, the wafer 10 is placed on the heating stage 30 for heating the substrate 11. The film forming temperature is about 500 ° C., for example. In this state, a mixed gas of WF ₆ and SiH ₄ is supplied from a gas supply unit that is disposed above the wafer 10 and covers the surface of the wafer 10, that is, the shower head 40. The supply amount and supply pressure of the mixed gas are appropriately selected according to the composition of the mixed gas and the size of the wafer 10. Here, the distance between the surface of the lower surface and the wafer 10 of the shower head 40 to which the mixed gas is ejected is H _1.

  After the supplied mixed gas reaches the surface of the wafer 10, a thermal decomposition reaction is caused by the heated substrate temperature, and the WSi film 14 is formed on the formed polysilicon film 13. As shown in this figure, the WSi film 14 is formed not only on the surface of the wafer 10 but also on the edge portion of the wafer 10.

Referring to FIG. 5, in the next film removal step, the shower head 40 is lowered to bring the shower head 40 close to the heating stage 30 on which the wafer 10 is placed, and between the lower surface of the shower head 40 and the surface of the wafer 10. as short as possible the distance H _2. That is, H ₂ << H ₁ is set. In this state, an inert gas such as Ar gas is allowed to flow from the lower surface of the shower head 40. On the other hand, ClF ₃ gas is supplied from the peripheral edge of the shower head 40 to the periphery of the wafer 10, preferably near the edge of the wafer 10, for example, at a flow rate of about 200 sccm. The etching gas only needs to be filled in a chamber (not shown) in which the wafer 10 is disposed, but is preferably supplied mainly near the edge of the wafer 10 of the wafer.

In response to the supply, ClF ₃ gas reaches the edge portion of the wafer 10 and etches the WSi film 14 and the polysilicon film 13. On the other hand, since Ar gas supplied from the shower head 40 flows outward from the center of the wafer 10 on the surface of the wafer 10, the ClF ₃ gas is not supplied to the surface of the wafer 10, The WSi film 14 and the polysilicon film 13 on the surface portion of the wafer 10 are not etched.

In the first embodiment, ClF ₃ gas is used as an etching gas, and the WSi film 14 is etched. In this case, the etching rate of the WSi film 14 is about 100 / sec, for example, and the etching rate of the polysilicon film 13 is about 500 / min. Although depending on the film thickness of the formed WSi film 14 and polysilicon film 13, these films can be removed in about several minutes. Further, the etching time can be further shortened by increasing the flow rate of the supplied ClF ₃ gas.

The etching gas is not limited to the ClF ₃ gas, and may be another appropriate gas that can remove the edge film. The etching gas is not necessarily supplied from the shower head 40, and may be supplied near the edge of the wafer 10 or in the chamber from another gas supply line. Furthermore, a gas supply line may be prepared so that the etching gas is jetted from the side toward the edge toward the edge of the wafer 10.

  Referring to FIG. 6, in the next element region forming step, general photolithography and etching techniques are performed on the wafer 10 in which the oxide film 12, the polysilicon film 13, and the WSi film 14 are formed on the substrate 11 as a result. A gate electrode having a desired pattern is formed as an element region 20 by using. In this figure, one element region 20 is shown as an example for ease of explanation, but it goes without saying that many element regions depend on the number of semiconductor elements to be formed on the wafer 10 and the structural specifications of the semiconductor elements. 20 can be formed.

  FIG. 7 shows the lower surface 41 and the peripheral edge 43 of the shower head 40. The lower surface 41 of the shower head 40 has a circular shape, for example, so as to cover the surface of the wafer. The lower surface 41 of the shower head 40 is provided with a number of downwardly directed injection ports 42 from which inert gas is injected. The inert gas is blocked by a surface portion (not shown) of the wafer disposed below the shower head 40 and flows out in the radial direction, that is, outward.

  On the other hand, the peripheral edge 43 of the shower head 40 is provided with a number of injection ports 44 toward the outside, from which etching gas is injected. The shape shown in this figure is one example, and there can be various showerhead shapes. The injection direction of the injection port 44 provided in the peripheral edge portion 43 is not limited to the outward direction, and may be directed toward the edge portion of the wafer.

  FIG. 8 shows how the chamber is used in the first embodiment. Referring to FIG. 8A, a chamber CA for film formation and film removal, a transfer chamber CT for transferring a wafer, and a load lock chamber CLR for holding a waiting wafer in vacuum are prepared. The The wafer to be processed is first held in the load lock chamber CLR and is kept in a vacuum. Next, the wafer is transferred to the chamber CA via the transfer chamber CT. In one chamber CA, film formation and film removal are consistently performed on the wafer through the above-described steps. The wafer on which film formation and film removal has been completed is unloaded from the chamber CA via the transfer chamber CT, returned to the load lock chamber CLR, and discharged or used for the next process.

  Referring to FIG. 8B, a temperature control sequence for the chamber CA is shown. Here, the heating stage temperature is maintained at 500 ° C. for film formation, and the post-deposition heating stage temperature is cooled from 500 ° C. to 200 ° C. Film removal is performed at a heating stage temperature of 200 ° C. Furthermore, the heating stage temperature is heated from 200 ° C. to 500 ° C. in order to form a film again for forming a gate electrode and the like. In this case, it is necessary to lower the heating stage temperature and raise the temperature.

In the first embodiment described above, one chamber (chamber CA in FIG. 8) in which the WSi film 14 and the polysilicon film 13 are formed without the step of carrying to a dedicated chamber for film removal is provided. ), The WSi film 14 and the polysilicon film 13 can be removed only from the edge portion of the wafer 10. Further, by adjusting the distance between the heating stage 30 and the shower head 40 and the Ar gas flow rate, the amount of ClF ₃ gas that wraps around the surface of the wafer 10 can be appropriately controlled, and as a result, the surface of the wafer 10 can be controlled. It is also possible to etch a part of these simultaneously. Further, since the apparatus for forming the WSi film 14 and the apparatus for removing the film can be implemented by the same apparatus, it is not necessary to prepare a separate apparatus for film removal unlike the conventional method.

  In the first embodiment, the WSi film 14 is formed after the WSi film 14 is formed, but the film of the edge portion is removed in the same apparatus or chamber. The film made of other materials of the edge portion can be removed by a similar method in an apparatus or chamber capable of film formation by a single wafer type without being limited to the apparatus.

  In the first embodiment, an example in which a Si substrate is used as the substrate 11 is shown. However, the present invention is not limited thereto, and may be a substrate that can be used in a semiconductor wafer process, such as a glass substrate or a SiC substrate. I just need it.

In the first embodiment, the polysilicon film 13 and the WSi film 14 at the edge portion of the wafer 10 are removed using ClF ₃ gas, but the material of the film to be etched is an etching such as ClF ₃ gas. For example, a film such as a SiN film, a Ti film, or a W film that can be removed with a gas may be used.

In the first embodiment, ClF ₃ gas is used as the etching gas, but any gas that can remove the film adhering to the edge portion may be used, and other types of gases may be used. .

  In the first embodiment, the lower surface of the shower head 40 has been described as completely covering the wafer 10. However, the present invention is not limited to this, and how far the outer shape of the wafer 10 is removed. The size of the lower surface of the shower head 40 may be determined based on the determination as to whether the wafer edge portion needs to be.

<Second embodiment>
FIG. 9 shows a mode of using a chamber in the second embodiment. Referring to FIG. 9A, the second embodiment is a mode in which film formation and film removal are performed in separate chambers. As shown in this figure, unlike the embodiment shown in FIG. 8, two chambers, a film formation chamber CA and a film removal chamber CB, are prepared.

  As the process execution order, first, the wafer is transferred to the chamber CA, and a WSi film is formed. After the film formation, the wafer is transferred to the chamber CB and the film removal described in the first embodiment is performed. In this manner, film formation and film removal are performed in separate chambers.

  Referring to FIGS. 9B and 9C, there are shown respective temperature control sequences of the film formation chamber CA and the film removal chamber CB. Here, in the chamber CA, the heating stage temperature is set to a constant value of about 500 ° C. in order to form the WSi film. On the other hand, the chamber CB is maintained at a constant temperature, for example, at a heating stage temperature of about 200 ° C. in order to perform film removal and suppress corrosion of components in the chamber CB.

  In the second embodiment described above, the chambers CA and CB can be processed while the heating stage temperature is always maintained at the same temperature. Therefore, the time required for the temperature lowering and the temperature rising can be shortened, and the time can be increased in a short time. It becomes possible to process the wafers. That is, it is possible to shorten the processing time required for each wafer.

  As described above, according to the semiconductor element manufacturing method of the present invention, it is also possible to reduce the number of processes without requiring a dedicated apparatus for film removal. In the preferred embodiment of the present invention, an etching gas is injected from the peripheral edge of the shower head toward the edge of the wafer and simultaneously an inert gas is injected onto the surface of the wafer 10. As a result, penetration of the etching gas into the wafer center is suppressed, and effective film removal is achieved.

DESCRIPTION OF SYMBOLS 10 Wafer 11 Substrate 12 Oxide film 13 Polysilicon film 14 WSi film 20 Element area 30 Heating stage 40 Shower head CLR Load lock chamber CT Transport chamber CA, CB chamber

Claims (9)

A semiconductor device manufacturing method for manufacturing at least one semiconductor device on a wafer-shaped substrate,
A film forming step of forming a film of at least one layer on the wafer surface of the substrate using a film forming material corresponding thereto;
While supplying an inert gas to the surface of the wafer on which the film has been formed, an etching gas suitable for the film forming material is supplied around the wafer on which the film has been formed. A film removal step for performing film removal;
A method for manufacturing a semiconductor device, comprising:   The film formation step is a step of supplying a film formation gas from a gas supply unit that covers the wafer surface, and the film removal step is performed by using the inert gas instead of the film formation gas from the gas supply unit. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the method is a supplying step.   3. The semiconductor device according to claim 2, wherein the film removing step includes a step of setting a distance between the gas supply unit and the wafer surface to be smaller than the distance in the film forming step. Production method.   3. The method of manufacturing a semiconductor device according to claim 2, wherein the film removing step is a step of supplying the etching gas from a peripheral edge of the gas supply unit.   2. The method of manufacturing a semiconductor device according to claim 1, wherein the film removing step is a step of supplying the etching gas toward a wafer edge mainly in the wafer portion.   Prior to the film removal step, the method further includes an inter-chamber transfer step for unloading the wafer on which the film formation step has been performed from the first chamber and loading the wafer into the second chamber. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the film is removed at an etching temperature suitable for the film forming material in the chamber.   2. The method of manufacturing a semiconductor device according to claim 1, wherein the at least one film includes a tungsten silicide film and a polysilicon layer.   2. The method of manufacturing a semiconductor device according to claim 1, wherein the substrate is a substrate containing Si as a main material.   2. The method of manufacturing a semiconductor device according to claim 1, wherein the etching gas is a gas capable of etching at least one of a tungsten silicide film and a polysilicon film.

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