CN116598193A - Method for forming polycrystalline silicon film and method for removing pollutants in LPCVD (low pressure chemical vapor deposition) process - Google Patents

Method for forming polycrystalline silicon film and method for removing pollutants in LPCVD (low pressure chemical vapor deposition) process Download PDF

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CN116598193A
CN116598193A CN202310867890.5A CN202310867890A CN116598193A CN 116598193 A CN116598193 A CN 116598193A CN 202310867890 A CN202310867890 A CN 202310867890A CN 116598193 A CN116598193 A CN 116598193A
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furnace tube
polysilicon film
forming
gas
polysilicon
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高勇强
施剑华
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Yuexin Semiconductor Technology Co ltd
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Yuexin Semiconductor Technology Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02518—Deposited layers
    • H01L21/02521—Materials
    • H01L21/02524—Group 14 semiconducting materials
    • H01L21/02532—Silicon, silicon germanium, germanium
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/24—Deposition of silicon only
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/4401—Means for minimising impurities, e.g. dust, moisture or residual gas, in the reaction chamber
    • C23C16/4405—Cleaning of reactor or parts inside the reactor by using reactive gases
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02518—Deposited layers
    • H01L21/02587—Structure
    • H01L21/0259—Microstructure
    • H01L21/02595—Microstructure polycrystalline
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02612—Formation types
    • H01L21/02617—Deposition types
    • H01L21/0262—Reduction or decomposition of gaseous compounds, e.g. CVD
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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Abstract

The invention provides a method for forming a polycrystalline silicon film and a method for removing pollutants in an LPCVD process, which are applied to the technical field of semiconductors. In the forming method and the removing method provided by the embodiments of the present invention, after each time the LPCVD process of the polysilicon film is performed in the reaction area of the furnace tube, a thermal oxidation process is performed again, so that the problem of surface pollution caused by that polysilicon particle pollutants formed by peeling and cracking of a local film of the second polysilicon film fall on the surface of the wafer and the first polysilicon film formed thereon due to the increase of the stress of the second polysilicon film along with the increase of the number of times of the LPCVD process performed in a single equipment maintenance period of the furnace tube due to the thickness of the second polysilicon film synchronously formed in the LPCVD process of the inner wall of the furnace tube in the reaction area is avoided.

Description

Method for forming polycrystalline silicon film and method for removing pollutants in LPCVD (low pressure chemical vapor deposition) process
Technical Field
The invention relates to the technical field of semiconductors, in particular to a method for forming a polycrystalline silicon film and a method for removing pollutants in an LPCVD process.
Background
Chemical vapor deposition (Chemical Vapor Deposition, CVD) is a chemical technology that is essentially a method of forming a thin film by chemical reaction of one or more vapor compounds or elements containing thin film elements on the surface of a wafer. Chemical vapor deposition is largely classified into atmospheric Pressure chemical vapor deposition (Atmospheric Pressure CVD, APCVD), low Pressure Chemical Vapor Deposition (LPCVD), and Plasma Enhanced Chemical Vapor Deposition (PECVD).
At present, the production equipment of the LPCVD process is mainly a furnace tube, and the LPCVD process (called the furnace tube LPCVD process for short) adopting the furnace tube as the production equipment has the advantages of high production efficiency, stable film quality, easy adjustment of film thickness and the like, and is mainly used for forming various films such as polysilicon, amorphous silicon, silicon nitride, silicon oxide and the like. Wherein, polysilicon is a material with larger stress.
However, in the process of depositing polysilicon on the wafer surface by using the furnace tube LPCVD process, a layer of polysilicon layer is formed on the inner wall of the furnace tube at the same time by the reaction gas, and the polysilicon layer deposited on the inner wall of the furnace tube is thickened along with the increase of the number of times of the furnace tube LPCVD process performed in a single equipment maintenance period (abbreviated as PM period) of the furnace tube, which will tend to cause the problem that the polysilicon layer on the inner wall of the furnace tube is peeled and broken under the action of self stress in the process of forming polysilicon with larger stress and then falls on the surface of the polysilicon layer deposited on the wafer, thereby causing the polysilicon layer to be polluted by particle pollutants and reducing the yield of device products.
Disclosure of Invention
The invention aims to provide a method for forming a polysilicon film and a method for removing pollutants in an LPCVD process, which are used for solving the problem that a second polysilicon film deposited on the inner wall of a furnace tube is thickened along with the increase of the times of the LPCVD process executed in a single equipment maintenance period of the furnace tube, and the second polysilicon film on the inner wall of the furnace tube is peeled and broken under the action of self stress so as to fall on the surface of a first polysilicon film deposited on a wafer, so that the first polysilicon film is polluted.
In order to solve the above technical problems, the present invention provides a method for forming a polysilicon film, which specifically includes the following steps:
and placing a wafer in a reaction area of a furnace tube, and performing an LPCVD (low pressure chemical vapor deposition) process on the wafer to form a first polysilicon film on the surface of the wafer, and forming a second polysilicon film on the inner wall of the furnace tube in the reaction area.
And transferring the wafer with the first polysilicon film from the reaction zone of the furnace tube to the loading zone of the furnace tube, and simultaneously introducing a first gas into the loading zone of the furnace tube so as to enable the first gas diffused into the reaction zone of the furnace tube and the surface layer of the second polysilicon film to perform a thermal oxidation process.
Further, the reaction zone and the loading zone of the furnace tube can be separated by a movable gate, and the temperature in the reaction zone of the furnace tube can be higher than the temperature in the loading zone of the furnace tube.
Further, after the step of introducing the first gas into the loading area of the furnace tube to perform the thermal oxidation process on the first gas diffused into the reaction area of the furnace tube and the surface layer of the second polysilicon film, the forming method further includes:
and removing the wafer with the first polysilicon film from the loading area of the furnace tube, and simultaneously introducing second gas into the loading area of the furnace tube to remove at least the first gas remained in the loading area of the furnace tube.
Further, the first gas may specifically include oxygen, and the second gas may specifically include nitrogen.
Further, when the first gas is introduced into the loading area of the furnace tube, the movable gate needs to be in an open state, and when the second gas is introduced into the loading area of the furnace tube, the movable gate is in a closed state.
Further, the first gas diffused into the reaction zone of the furnace tube and the surface layer of the second polysilicon film are subjected to a thermal oxidation process, and simultaneously, the surface layer of the first polysilicon film is synchronously thermally oxidized into silicon dioxide.
Further, after the step of removing the first polysilicon thin film having the surface simultaneously thermally oxidized to silicon dioxide from the loading area of the furnace tube, the forming method provided in the embodiment of the present invention may further include the steps of:
and carrying out a wet cleaning process on the first polysilicon film with the surface being synchronously thermally oxidized into silicon dioxide so as to remove the silicon dioxide.
Furthermore, the cleaning solution adopted in the wet cleaning process can be specifically an acid cleaning solution, and the acid cleaning solution can specifically comprise hydrofluoric acid.
In a second aspect, based on the method for forming a polysilicon film as described above, the present invention further provides a method for removing contaminants in an LPCVD process, where the LPCVD process uses a furnace tube as a reaction chamber, and specifically may use the steps of the method for forming a polysilicon film as described above.
Further, in the method for removing a contaminant in an LPCVD process provided in the embodiment of the present invention, the contaminant to be removed is specifically attached to the inner wall of the furnace tube, and the contaminant may specifically include polysilicon, that is, the method for removing a contaminant in an LPCVD process is to remove a polysilicon film attached to the inner wall of the furnace tube.
Compared with the prior art, the technical scheme of the invention has at least one of the following beneficial effects:
the invention provides a method for forming a polycrystalline silicon film and a method for removing pollutants in an LPCVD process, which comprises the steps of firstly placing a wafer in a reaction area of a furnace tube, and performing the LPCVD process on the wafer to form a first polycrystalline silicon film on the surface of the wafer, and forming a second polycrystalline silicon film on the inner wall of the furnace tube in the reaction area; and transferring the wafer with the first polysilicon film from the reaction zone of the furnace tube to the loading zone of the furnace tube, and simultaneously introducing a first gas into the loading zone of the furnace tube so as to enable the first gas diffused into the reaction zone of the furnace tube and the surface layer of the second polysilicon film to perform a thermal oxidation process.
In the forming method and the removing method provided by the embodiments of the present invention, after each time the LPCVD process of the polysilicon film is performed in the reaction area of the furnace tube, a thermal oxidation process is performed again, so that the problem of surface pollution caused by that polysilicon particle pollutants formed by peeling and cracking of a local film of the second polysilicon film fall on the surface of the wafer and the first polysilicon film formed thereon due to the increase of the stress of the second polysilicon film along with the increase of the number of times of the LPCVD process performed in a single equipment maintenance period of the furnace tube due to the thickness of the second polysilicon film synchronously formed in the LPCVD process of the inner wall of the furnace tube in the reaction area is avoided.
Moreover, according to the forming method and the removing method provided by the invention, since the surface stress of the second polysilicon film deposited on the inner wall in the reaction zone of the furnace tube for a single time can be reduced, compared with the surface stress of the second polysilicon film with the accumulated thickness formed after the LPCVD process is performed for the preset times in the reaction zone of the furnace tube in the prior art, the surface stress of the second polysilicon film with the accumulated thickness covered on the inner wall in the reaction zone of the furnace tube in the embodiment of the invention is much smaller than the surface stress of the second polysilicon film, namely, compared with the prior art, the unexpected beneficial effects that the invention can realize are that: the surface cleanliness of the first polysilicon film formed on the wafer is improved, and meanwhile, the total number of LPCVD processes which can be executed in a single equipment maintenance period of the LPCVD process, the machine yield and the yield of semiconductor devices are also improved.
Drawings
Fig. 1 is a flow chart of a method for forming a polysilicon film according to an embodiment of the invention.
FIG. 2 is a simplified schematic diagram of a furnace having a reaction zone and a loading zone separated by a movable gate according to one embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a second polysilicon film with a cumulative thickness formed on an inner wall of a reaction zone of a furnace tube after performing an LPCVD process a plurality of times in a single equipment maintenance cycle of the LPCVD process according to the method for forming a polysilicon film according to an embodiment of the present invention.
Fig. 4 is a graph showing a comparison of surface stress of a second polysilicon film coated on an inner wall of a reaction region of a furnace tube after performing LPCVD processes several times in a single equipment maintenance cycle of LPCVD processes according to the prior art and the method for forming a polysilicon film according to the embodiment of the present invention.
Detailed Description
In order to make the technical scheme and advantages of the embodiments of the present invention more clear, the technical scheme of the present invention will be further described in detail below with reference to the accompanying drawings and the embodiments. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
The invention is more particularly described by way of example in the following paragraphs with reference to the drawings. Advantages and features of the invention will become more apparent from the following description and from the claims. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for convenience and clarity in aiding in the description of embodiments of the invention. It is to be understood that the meanings of "on … …", "over … …" and "over … …" in the present invention are to be interpreted in the broadest sense so that "on … …" means not only that it is "on" something with no intervening features or layers therebetween (i.e., directly on something), but also that it is "on" something with intervening features or layers therebetween.
Further, spatially relative terms such as "on … …," "above … …," "above … …," "upper" and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated for ease of description. In addition to the orientations depicted in the drawings, the spatially relative terms are intended to encompass different orientations of the device in use or operation. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
In embodiments of the present invention, the term "substrate" or "semiconductor substrate" refers to a material to which subsequent material layers are added. The substrate itself may be patterned. The material added on top of the substrate or on top of the semiconductor substrate may be patterned or may remain unpatterned.
In embodiments of the present invention, the term "layer" refers to a portion of material that includes regions having a thickness. The layer may extend over the entirety of the underlying or overlying structure, or may have a range that is less than the range of the underlying or overlying structure. Further, the layer may be a region of homogeneous or heterogeneous continuous structure having a thickness less than the thickness of the continuous structure. For example, the layer may be located between the top and bottom surfaces of the continuous structure, or the layer may be between any horizontal facing at the top and bottom surfaces of the continuous structure. The layers may extend horizontally, vertically and/or along an inclined surface. The layer may comprise a plurality of sub-layers. For example, the interconnect layer may include one or more conductors and contact sublayers (in which interconnect lines and/or via contacts are formed), and one or more dielectric sublayers.
In embodiments of the present invention, the terms "first," "second," and the like are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. The technical schemes described in the embodiments of the present invention may be arbitrarily combined without any collision.
As known in the related art, the surface stress of a polysilicon material is much greater than that of silicon dioxide due to the characteristics of the material itself. Moreover, the warpage of the wafer is related to the type of thin film and the thickness of the thin film formed on the surface thereof, and generally the warpage of the polysilicon thin film to the wafer is greatly changed, and it is also increased with the increase of the thickness of the polysilicon thin film.
According to the prior art, the present inventors have found that, during the process of depositing polysilicon on the wafer surface by the furnace tube LPCVD process, a layer of polysilicon layer is formed on the inner wall of the furnace tube at the same time by the reaction gas, and the polysilicon layer deposited on the inner wall of the furnace tube is thickened with the increase of the number of times of the furnace tube LPCVD process performed in a single equipment maintenance period (abbreviated as PM period) of the furnace tube, which will tend to cause the problem that the polysilicon layer on the inner wall of the furnace tube is peeled and broken under the stress of itself during the process of forming polysilicon with larger stress, and then falls on the surface of the polysilicon layer deposited on the wafer, thereby causing the polysilicon layer to be contaminated by the particulate contaminant and reducing the yield of the device product.
Therefore, the researchers provided by the invention can reduce the surface stress of the polysilicon film which is covered on the inner wall in the reaction zone of the furnace tube and can generate local shedding fracture by performing thermal oxidation on at least part of the surface layer of the polysilicon film to convert the polysilicon film into silicon dioxide, thereby solving the technical problems.
That is, the embodiment of the invention provides a method for forming a polysilicon film and a method for removing pollutants in an LPCVD process, so as to solve the problem that a second polysilicon film deposited on the inner wall of a furnace tube is thickened along with the increase of the number of LPCVD processes executed in a single equipment maintenance period of the furnace tube, and the second polysilicon film on the inner wall of the furnace tube is peeled and broken under the action of self stress so as to fall off the surface of a first polysilicon film deposited on a wafer, thereby causing the pollution of the first polysilicon film.
The method for forming the polysilicon thin film in the embodiment of the present invention will be described below with reference to the accompanying drawings. Referring to fig. 1 to 2, fig. 1 is a schematic flow chart of a method for forming a polysilicon film according to an embodiment of the invention, and fig. 2 is a schematic structural diagram of a furnace tube including a reaction zone and a loading zone separated by a movable gate according to an embodiment of the invention.
As shown in fig. 1, the method for forming a polysilicon film provided by the present invention at least includes the following steps:
step S101, a wafer is placed in a reaction area of a furnace tube, and LPCVD technology is carried out on the wafer so as to form a first polysilicon film on the surface of the wafer, and meanwhile, a second polysilicon film is formed on the inner wall of the furnace tube in the reaction area.
And step S102, transferring the wafer with the first polysilicon film from the reaction zone of the furnace tube to the loading zone of the furnace tube, and simultaneously introducing a first gas into the loading zone of the furnace tube so as to enable the first gas diffused into the reaction zone of the furnace tube and the surface layer of the second polysilicon film to perform a thermal oxidation process.
In step S101, a polysilicon thin film is typically formed on a semiconductor substrate or wafer, preferably, a silicon wafer is used in the embodiment of the present invention, and then the provided silicon wafer is placed in a furnace tube, specifically, a furnace tube currently used generally includes a reaction zone, specifically, a high-temperature reaction zone, for performing a low-pressure high-temperature reaction of an LPCVD process, and a loading zone, specifically, a normal-temperature zone, for performing a residual gas purge of the reaction zone and temporary wafer buffering after the LPCVD process. As shown in FIG. 2, the reaction zone 1 and the loading zone 2 of the furnace tube can be separated by a movable gate 3.
In this step, one or a lot of lot wafers (silicon wafers) are placed in the reaction area of the furnace tube, and then a reaction gas for forming a polysilicon film is introduced into the reaction area, and preferably, the reaction gas for forming a polysilicon film on a silicon wafer may be silane gas. And then, adjusting the temperature and the air pressure in the reaction area of the furnace tube, and performing an LPCVD process once to form a layer of first polysilicon film on the surface of the one or a batch of lot wafers, and at the same time, covering a layer of second polysilicon film on the inner wall in the reaction area of the furnace tube.
It will be appreciated that the semiconductor substrate provided in embodiments of the present invention may be specifically any suitable substrate known in the art, for example, at least one of the following materials: silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbon (SiC), silicon germanium carbon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III/V compound semiconductors, and also include multilayer structures composed of these semiconductors, or the like, or are silicon-on-insulator (SOI), silicon-on-insulator (SSOI), silicon-on-insulator (S-SiGeOI), silicon-on-insulator (SiGeOI), and germanium-on-insulator (GeOI), or may be double-sided polished silicon wafers (Double Side Polished Wafers, DSP), or may be ceramic substrates such as alumina, quartz, or glass substrates, or the like. The semiconductor substrate in this embodiment is, for example, a silicon wafer.
In the step S102, after performing an LPCVD process on one or a batch of lot wafers in the reaction area, the movable gate is opened, and then the wafer with the first polysilicon film formed therein is moved down from the reaction area of the furnace tube to the loading area of the furnace tube, and simultaneously, the first gas, such as oxygen, is introduced into the loading area of the furnace tube, and the movable gate is opened, so that the oxygen introduced into the loading area diffuses into the reaction area, and then performs a thermal oxidation reaction with the second polysilicon film formed on the inner wall of the furnace tube in the reaction area, that is, at least part of the surface layer of the second polysilicon film is converted into silicon dioxide, thereby avoiding the problem of surface pollution caused by the falling of polysilicon particle pollutants formed by the local film peeling and cracking of the second polysilicon film on the surface of the lot of lot wafers and the first polysilicon film formed thereon.
Meanwhile, the wafer in the loading area, on which the first polycrystalline silicon film is formed, is oxidized by oxygen, so that part of the surface layer of the first polycrystalline silicon film is oxidized by silicon dioxide, and the warping probability of the wafer is reduced by thinning and reducing the thickness and the surface stress of the first polycrystalline silicon film formed on the surface of the wafer.
After the step S102 is performed, the method for forming a polysilicon thin film according to the embodiment of the present invention further includes:
step S103, removing the wafer with the first polysilicon film formed therein from the loading area of the furnace tube, and simultaneously introducing a second gas into the loading area of the furnace tube to remove the first gas (oxygen) remaining in the loading area of the furnace tube. As a preferable example, the second gas is nitrogen.
Step S104, performing a wet cleaning process on the first polysilicon film with the surface being synchronously thermally oxidized into silicon dioxide so as to remove the silicon dioxide. As a preferred example, the cleaning liquid used in the wet cleaning process is an acid cleaning liquid, and the acid cleaning liquid includes hydrofluoric acid.
It should be noted that, in the above-mentioned steps S101 to S104 only show the process of performing the LPCVD process and the thermal oxidation process, in the method for forming a polysilicon film provided in the embodiment of the present invention, it is generally required to perform the LPCVD process on wafers of different lot types according to a single equipment maintenance cycle of the LPCVD process, and in this case, the formation of the polysilicon film provided in the embodiment of the present invention is that the thermal oxidation process is performed again after each LPCVD process of the polysilicon film is performed in the reaction area of the furnace tube, so after the LPCVD process is performed for a plurality of times included in the single equipment maintenance cycle of the LPCVD process, the film structure formed on the inner wall of the reaction area of the furnace tube should be the stacked structure of the second polysilicon film, the silicon dioxide film, the second polysilicon film and the silicon dioxide film, as shown in fig. 3.
In addition, according to the relationship between the stress and the thickness of the polysilicon thin film, it is known that, during a single equipment maintenance period of the LPCVD process, the surface stress of the second polysilicon thin film stacked on the inner wall of the reaction zone of the furnace tube in turn may not reach the stress threshold value during the previous several LPCVD processes, and therefore, during this process, the second polysilicon thin film may not fall off and crack to form polysilicon particle contaminants, but as the number of LPCVD processes performed in the reaction zone of the furnace tube increases gradually, the second polysilicon thin film stacked on the inner wall of the reaction zone of the furnace tube will fall off and crack after a certain LPCVD process, for example, as shown by the dotted line in fig. 4, during the manufacturing method of the existing polysilicon thin film, it is generally the problem of falling off and polysilicon particle contamination of the subsequent wafer after the 4 th LPCVD process in the single equipment maintenance period, whereas, according to the solid line in fig. 4, the problem of falling off and polysilicon particle contamination of the subsequent wafer occurs after the 6 th LPCVD process in the single equipment maintenance period of the present embodiment of the polysilicon thin film.
In fig. 4, the dashed line is a stress trend graph of a second polysilicon film formed on an inner wall of a reaction region of a furnace tube after performing a plurality of LPCVD processes in a single equipment maintenance period of an LPCVD process by using a related art method for forming a polysilicon film, and the solid line is a stress trend graph of a second polysilicon film formed on an inner wall of a reaction region of a furnace tube after performing a plurality of LPCVD processes in a single equipment maintenance period of an LPCVD process by using the method for forming a polysilicon film provided in the embodiment of the present invention, where "Pre" indicates that "1st DEP PLOY~6st DEP PLOY" indicates that 1st to 6 th LPCVD processes are performed and "Oxidation" indicates silicon dioxide, respectively, before performing an LPCVD process.
Obviously, the surface stress of the second polysilicon film with the accumulated thickness covered on the inner wall in the reaction zone of the furnace tube in the embodiment of the invention is much smaller than that in the prior art, that is, the forming method provided by the embodiment of the invention can realize the beneficial effects to be achieved.
In addition, based on the inventive concept and the inventive steps of the method for forming a polysilicon film as described above, the embodiments of the present invention further provide a method for removing contaminants in an LPCVD process, where the LPCVD process uses a furnace tube as a reaction chamber, and the removing method at least includes the method for forming a polysilicon film as described above, which will not be described again. And, the pollutant removed by the removing method is attached to the inner wall of the furnace tube, and the pollutant comprises polysilicon.
In summary, the present invention provides a method for forming a polysilicon film and a method for removing contaminants in an LPCVD process, which comprises placing a wafer in a reaction region of a furnace tube, and performing an LPCVD process on the wafer to form a first polysilicon film on a surface of the wafer, and forming a second polysilicon film on an inner wall of the furnace tube in the reaction region; and transferring the wafer with the first polysilicon film from the reaction zone of the furnace tube to the loading zone of the furnace tube, and simultaneously introducing a first gas into the loading zone of the furnace tube so as to enable the first gas diffused into the reaction zone of the furnace tube and the surface layer of the second polysilicon film to perform a thermal oxidation process.
In the forming method and the removing method provided by the embodiments of the present invention, after each time the LPCVD process of the polysilicon film is performed in the reaction area of the furnace tube, a thermal oxidation process is performed again, so that the problem of surface pollution caused by that polysilicon particle pollutants formed by peeling and cracking of a local film of the second polysilicon film fall on the surface of the wafer and the first polysilicon film formed thereon due to the increase of the stress of the second polysilicon film along with the increase of the number of times of the LPCVD process performed in a single equipment maintenance period of the furnace tube due to the thickness of the second polysilicon film synchronously formed in the LPCVD process of the inner wall of the furnace tube in the reaction area is avoided.
Moreover, according to the forming method and the removing method provided by the invention, since the surface stress of the second polysilicon film deposited on the inner wall in the reaction zone of the furnace tube for a single time can be reduced, compared with the surface stress of the second polysilicon film with the accumulated thickness formed after the LPCVD process is performed for the preset times in the reaction zone of the furnace tube in the prior art, the surface stress of the second polysilicon film with the accumulated thickness covered on the inner wall in the reaction zone of the furnace tube in the embodiment of the invention is much smaller than the surface stress of the second polysilicon film, namely, compared with the prior art, the unexpected beneficial effects that the invention can realize are that: the surface cleanliness of the first polysilicon film formed on the wafer is improved, and meanwhile, the total number of LPCVD processes which can be executed in a single equipment maintenance period of the LPCVD process, the machine yield and the yield of semiconductor devices are also improved.
It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
In this specification, each embodiment is described in a related manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for apparatus, electronic devices, and computer-readable storage medium embodiments, the description is relatively simple, as it is substantially similar to method embodiments, with reference to portions of the description of method embodiments being relevant.
The foregoing description is only of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims (10)

1. A method for forming a polysilicon film, comprising:
placing a wafer in a reaction zone of a furnace tube, and performing an LPCVD (low pressure chemical vapor deposition) process on the wafer to form a first polysilicon film on the surface of the wafer, wherein a second polysilicon film is formed on the inner wall of the furnace tube in the reaction zone;
and transferring the wafer with the first polysilicon film from the reaction zone of the furnace tube to the loading zone of the furnace tube, and simultaneously introducing a first gas into the loading zone of the furnace tube so as to enable the first gas diffused into the reaction zone of the furnace tube and the surface layer of the second polysilicon film to perform a thermal oxidation process.
2. The method of forming a polysilicon film according to claim 1, wherein the reaction zone of the furnace tube and the loading zone thereof are separated by a movable gate, and the temperature in the reaction zone of the furnace tube is higher than the temperature in the loading zone thereof.
3. The method of forming a polysilicon film according to claim 2, wherein after the step of introducing a first gas into the loading region of the furnace tube to cause the first gas diffused into the reaction region of the furnace tube to perform a thermal oxidation process with the surface layer of the second polysilicon film, the method further comprises:
and removing the wafer with the first polysilicon film from the loading area of the furnace tube, and simultaneously introducing second gas into the loading area of the furnace tube to remove the residual first gas in the loading area of the furnace tube.
4. The method of forming a polysilicon film according to claim 3, wherein the first gas comprises oxygen and the second gas comprises nitrogen.
5. The method of forming a polysilicon film according to claim 3, wherein the movable gate is in an open state when the first gas is introduced into the loading region of the furnace tube, and in a closed state when the second gas is introduced into the loading region of the furnace tube.
6. The method of forming a polysilicon film according to claim 3, wherein the surface layer of the first polysilicon film is simultaneously thermally oxidized to silicon dioxide while the first gas diffused into the reaction zone of the furnace tube and the surface layer of the second polysilicon film are subjected to a thermal oxidation process.
7. The method of forming a polysilicon film according to claim 6, wherein after the step of removing the first polysilicon film having its surface simultaneously thermally oxidized to silicon dioxide from the loading zone of the furnace tube, the method further comprises:
and carrying out a wet cleaning process on the first polysilicon film with the surface being synchronously thermally oxidized into silicon dioxide so as to remove the silicon dioxide.
8. The method of forming a polysilicon film according to claim 7, wherein the cleaning liquid used in the wet cleaning process is an acid cleaning liquid, and the acid cleaning liquid comprises hydrofluoric acid.
9. A method for removing contaminants in an LPCVD process using a furnace tube as a reaction chamber, characterized in that the method for removing contaminants comprises the method for forming a polysilicon film according to any one of claims 1 to 8.
10. The method of removing contaminants from an LPCVD process of claim 9, wherein the contaminants removed by the removal method adhere to an inner wall of the furnace tube, the contaminants comprising polysilicon.
CN202310867890.5A 2023-07-17 2023-07-17 Method for forming polycrystalline silicon film and method for removing pollutants in LPCVD (low pressure chemical vapor deposition) process Pending CN116598193A (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5254176A (en) * 1992-02-03 1993-10-19 Tokyo Electron Limited Method of cleaning a process tube
JP2002313740A (en) * 2001-04-17 2002-10-25 Seiko Epson Corp Semiconductor manufacturing equipment
CN1434484A (en) * 2002-01-23 2003-08-06 旺宏电子股份有限公司 Method for removing residual polycrystalline silicon
CN116288267A (en) * 2023-01-06 2023-06-23 粤芯半导体技术股份有限公司 Technological method for furnace tube

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5254176A (en) * 1992-02-03 1993-10-19 Tokyo Electron Limited Method of cleaning a process tube
JP2002313740A (en) * 2001-04-17 2002-10-25 Seiko Epson Corp Semiconductor manufacturing equipment
CN1434484A (en) * 2002-01-23 2003-08-06 旺宏电子股份有限公司 Method for removing residual polycrystalline silicon
CN116288267A (en) * 2023-01-06 2023-06-23 粤芯半导体技术股份有限公司 Technological method for furnace tube

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