CN116613055B - Method for forming doped polysilicon film and method for removing surface defect thereof - Google Patents

Method for forming doped polysilicon film and method for removing surface defect thereof Download PDF

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CN116613055B
CN116613055B CN202310876715.2A CN202310876715A CN116613055B CN 116613055 B CN116613055 B CN 116613055B CN 202310876715 A CN202310876715 A CN 202310876715A CN 116613055 B CN116613055 B CN 116613055B
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pressure
doped polysilicon
polysilicon film
low
furnace tube
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CN116613055A (en
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高勇强
施剑华
巩雨锋
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Yuexin Semiconductor Technology Co ltd
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    • C30—CRYSTAL GROWTH
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    • H01L21/02068—Cleaning during device manufacture during, before or after processing of conductive layers, e.g. polysilicon or amorphous silicon layers
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Abstract

The invention provides a method for forming a doped polysilicon film and a method for removing surface defects of the doped polysilicon film, which are applied to the technical field of semiconductors. Firstly dividing the total time for forming the doped polysilicon film into a plurality of groups of time periods, wherein each group of time periods consists of a first time period and a second time period, then, circularly executing the LPCVD process for the first time period and the second time period for a preset number of times in a low-pressure furnace tube, setting the air pressure in the low-pressure furnace tube of the LPCVD process as low pressure and introducing a proper amount of reaction gas source in the first time period, reducing the air pressure in the low-pressure furnace tube from the low pressure to 0 in the second time period, simultaneously rapidly discharging the residual reaction gas source and byproducts in the low-pressure furnace tube, and then, after the total time period, returning the air pressure in the low-pressure furnace tube to a normal pressure state, introducing oxidizing gas into the low-pressure furnace tube so as to perform thermal oxidation treatment on the surface of the doped polysilicon film.

Description

Method for forming doped polysilicon film and method for removing surface defect thereof
Technical Field
The invention relates to the technical field of semiconductors, in particular to a method for forming a doped polysilicon film and a method for removing surface defects of the doped polysilicon film.
Background
Polysilicon is commonly used as a gate material in various semiconductor devices, and film formation and simultaneous phosphorus doping are generally performed using a furnace tube low pressure deposition process (abbreviated as LPCVD process) and an in-situ doping process to adjust the resistance of the polysilicon thin film. And then, forming a contact hole in a dielectric layer covered on the surface of the polysilicon by utilizing an etching process, wherein the contact hole can be directly electrically connected with a grid electrode and a source electrode and a drain electrode of the device and can be also used for electrically connecting layers.
However, in the in-situ doping film forming process of the polysilicon film, excessive phosphorus doping elements are easily accumulated on the surface of the wafer (or the surface of the semiconductor) to form crystal nuclei, and along with the continuous increase of the film thickness of the polysilicon film, bulge defects of phosphorus impurities on the surface of the polysilicon film tend to occur, and the bulge defects further cause the abnormality of subsequent exposure, development and etching processes, and finally cause the problem of the reduction of the yield of the semiconductor device.
Disclosure of Invention
The invention aims to provide a method for forming a doped polysilicon film and a method for removing surface defects of the doped polysilicon film, so as to solve the problem that the surface of the doped polysilicon film is bulged due to redundant doping elements, and the yield of a semiconductor device is reduced.
In order to solve the above technical problems, the present invention provides a method for forming a doped polysilicon thin film, which is specifically applicable to an LPCVD process using a low pressure furnace tube as a reaction apparatus, and the method includes the following steps:
step S1, a semiconductor substrate is placed in the low-pressure furnace tube, and under the condition that the pressure in the low-pressure furnace tube is set to be a first pressure, a reaction gas source with a first duration is introduced into the low-pressure furnace tube, wherein the reaction gas source comprises a doping gas source and a film gas source, and a doped polycrystalline silicon film with a partial thickness is formed on the surface of the semiconductor substrate in a mode of utilizing an LPCVD process and simultaneously carrying out in-situ doping.
And S2, stopping introducing the reaction gas source after the first time period, and introducing an exhaust gas source for a second time period into the low-pressure furnace tube under the condition that the pressure in the low-pressure furnace tube is set to be a second pressure so as to at least remove the residual reaction gas source in the low-pressure furnace tube, wherein the first pressure is higher than the second pressure.
And step S3, after the second time period, sequentially returning to execute the step S1 and the step S2 until the preset times are circularly executed, setting the in-tube pressure of the low-pressure furnace tube to be a third air pressure, simultaneously introducing oxidizing gas into the low-pressure furnace tube, and performing thermal oxidation treatment on the surface of the target doped polysilicon film formed after the preset times of the step S1 and the step S2, wherein the third air pressure is higher than the first air pressure.
Further, the time proportion range of the first duration and the second duration may specifically be: 3:1 to 10:1.
Further, the preset times for sequentially executing the step S1 and the step S2 by the semiconductor substrate may specifically be: 3to 10 times, preferably 5 times.
Further, the pressure range of the first pressure may be specifically 0.1Torr to 3Torr, the second pressure may be specifically 0Torr, the third pressure may be specifically atmospheric pressure (also may be understood as normal pressure), and the pressure range of the first pressure is preferably 0.6Torr.
Further, the reactive gas source may include a silane gas, and the dopant gas source may include a phosphine gas.
Further, the exhaust gas source may include nitrogen gas, and the oxidizing gas may include oxygen gas.
Further, the target doped polysilicon film may specifically be a phosphorus doped polysilicon film, where a bulge defect exists on the surface of the phosphorus doped polysilicon film, and the component of the bulge defect includes polysilicon.
Further, the step S3 of performing a thermal oxidation treatment on the surface of the target doped polysilicon thin film may specifically include: and oxidizing and converting part of the thickness surface of the phosphorus doped polysilicon film with the bulge defects into silicon dioxide.
Further, after the step S3, the method for forming a doped polysilicon thin film provided by the present invention may further include: and S4, performing a cleaning process on the phosphorus-doped polysilicon film with the surface oxidized into the silicon dioxide so as to remove all the silicon dioxide on the surface of the phosphorus-doped polysilicon film.
Furthermore, the cleaning solution adopted in the cleaning process can be specifically an acid cleaning solution, and the acid cleaning solution can be specifically hydrofluoric acid.
In a second aspect, based on the method for forming a doped polysilicon film as described above, the present invention further provides a method for removing surface defects of a doped polysilicon film, which specifically may adopt the method for forming a doped polysilicon film as described above, so as to form a doped polysilicon film accordingly.
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 doped polysilicon film and a method for removing surface defects of the doped polysilicon film, wherein the method comprises the steps of dividing the total time for forming the doped polysilicon film into a plurality of groups of time periods, wherein each group of time periods consists of a first time period and a second time period, then, circularly executing LPCVD (low pressure chemical vapor deposition) processes for the first time period and the second time period for a preset number of times in a low pressure furnace tube, setting the air pressure in the low pressure furnace tube of the LPCVD process to be low pressure (first air pressure) and introducing a proper amount of reaction gas source in the first time period, reducing the air pressure in the low pressure furnace tube from the low pressure to 0 (second air pressure) in the second time period, simultaneously rapidly discharging the residual reaction gas source and byproducts in the low pressure furnace tube, and then, after the total time period, raising the air pressure in the low pressure furnace tube back to a normal pressure state (third air pressure), introducing oxidizing gas (oxygen) in the low pressure furnace tube, so as to perform thermal oxidation treatment on the surface of the doped polysilicon film.
The invention adopts a plurality of low-pressure deposition-depressurization air suction byproduct removal cycles, and the reaction is carried out for a certain time in each cycle to form the doped polysilicon film, and then redundant reaction gas and byproduct removal are carried out on the doped polysilicon film immediately, so that the problem of bulge defect on the surface of the doped polysilicon film (such as a phosphorus doped polysilicon film) caused by aggregation of doping elements (such as phosphorus ions) is solved in a plurality of stages in the film formation process.
And after the repeated 'low-pressure deposition-depressurization and air extraction byproduct removal' circulation, further utilizing a thermal oxidation process to convert the bulge defects existing on the surface of the formed doped polysilicon film into silicon dioxide, namely consuming at least part of polysilicon in the bulge defects, and then utilizing an acidic cleaning solution to remove the silicon dioxide, thereby achieving the purpose of effectively removing the bulge defects generated on the surface of the phosphorus doped polysilicon film and finally improving the yield of semiconductor devices.
Drawings
Fig. 1 is a flow chart of a method for forming a doped polysilicon film according to an embodiment of the invention.
FIG. 2 is a graph showing whether the reactant gas source, the oxidizing gas source, the duration of the reactant gas source and the oxidizing gas are introduced and the gas pressure in the furnace according to the embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a bulge defect occurring on the surface of a phosphorus doped polysilicon film during the formation of the phosphorus doped polysilicon film in the prior art.
Fig. 4 is a schematic structural diagram of a phosphorus doped polysilicon film with bulge defects according to an embodiment of the present invention after oxidizing and converting a portion of the thickness surface of the phosphorus doped polysilicon film into silicon dioxide by the method shown in fig. 1.
Fig. 5 is a schematic diagram of a structure with reduced bulge defects after performing a cleaning process on the structure shown in fig. 4 by using the forming method according to an embodiment of the present invention.
In fig. 3to 4,
100-a semiconductor substrate; a 110-phosphorus doped polysilicon film;
120-silicon dioxide.
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.
According to the related art, during the in-situ doping LPCVD process of the phosphorus doped polysilicon film, excessive phosphorus doped elements are easily accumulated on the surface of the polysilicon film to form crystal nuclei, and as the film thickness of the phosphorus doped polysilicon film is continuously increased, the surface of the phosphorus doped polysilicon film tends to have bulge defects which jack up the surface of the polysilicon film, and the bulge defects further cause the abnormality of subsequent exposure, development and etching processes, and finally cause the problem of reduced yield of semiconductor devices.
According to the prior art, the present inventors have found that the bulge defect existing on the surface of the doped polysilicon thin film, for example, the phosphorus doped polysilicon thin film, is a bulge structure containing the doping element therein and having the surface of polysilicon, as shown in fig. 3, and the bulge defect is formed by gradually stacking during the gradual formation of the staged film layer of the doped polysilicon thin film, and therefore, the present inventors have proposed an inventive concept based on this, which can divide the formation process of the doped polysilicon thin film, then, during the gradual formation process of the doped polysilicon thin film, stage-remove the bulge defect occurring therein, and then, after finally stacking the formed doped polysilicon thin film, perform a thermal oxidation treatment and an acidic solution cleaning treatment on the surface of the doped polysilicon thin film to convert the surface polysilicon of the bulge defect existing on the surface of the finally formed doped polysilicon, and clean and remove the bulge defect existing on the surface of the doped polysilicon thin film with an acidic solution, thereby finally realizing the removal of the bulge defect existing on the surface of the doped polysilicon thin film.
Therefore, the invention provides a method for forming a doped polysilicon film and a method for removing surface defects thereof, so as to solve the problem that the surface of the formed doped polysilicon film is bulged due to redundant doping elements, thereby reducing the yield of semiconductor devices.
The following describes the formation method of the doped polysilicon thin film provided in the embodiments of the present invention by referring to the drawings.
Referring to fig. 1, fig. 1 is a flow chart illustrating a method for forming a doped polysilicon thin film according to an embodiment of the invention.
It should be noted that the method for forming a doped polysilicon thin film provided in the embodiment of the invention is a forming method particularly suitable for an LPCVD process using a low pressure furnace tube as a reaction apparatus.
Specifically, as shown in fig. 1, the method for forming the doped polysilicon thin film provided by the invention at least includes the following steps:
step S1, a semiconductor substrate is placed in the low-pressure furnace tube, and under the condition that the pressure in the low-pressure furnace tube is set to be a first pressure, a reaction gas source with a first duration is introduced into the low-pressure furnace tube, wherein the reaction gas source comprises a doping gas source and a film gas source, and a doped polycrystalline silicon film with a partial thickness is formed on the surface of the semiconductor substrate in a mode of utilizing an LPCVD process and simultaneously carrying out in-situ doping.
And S2, stopping introducing the reaction gas source after the first time period, and introducing an exhaust gas source for a second time period into the low-pressure furnace tube under the condition that the pressure in the low-pressure furnace tube is set to be a second pressure so as to at least remove the residual reaction gas source in the low-pressure furnace tube, wherein the first pressure is higher than the second pressure.
In this embodiment, after determining the target thickness of the doped polysilicon film to be formed, the total reaction time for forming the doped polysilicon film this time is determined by referring to the sum of the target thickness and the thickness of the silicon dioxide to be oxidized and converted into by the surface of the doped polysilicon film (the surface having the bulge defect) in the step S3 in the embodiment of the present invention, and then the total reaction time is divided into a plurality of groups of time periods, each group of time periods being composed of a first time period T1 and a second time period T2, that is, the total reaction time is divided into a plurality of groups (t1+t2) of time periods, and the process performed during each of the divided groups (t1+t2) of time periods is regarded as a cycle.
Then, a first cycle is performed, specifically, a semiconductor substrate prepared in advance may be placed on a bearing table of a low-pressure furnace tube prepared in advance, then, a reaction gas source of the first duration T1 is introduced into the low-pressure furnace tube, and the in-tube gas pressure of the low-pressure furnace tube is set to a first gas pressure (low pressure), the reaction gas source is a mixed gas source for forming a doped polysilicon film, so that a doped polysilicon film with a certain thickness is formed on the surface of the semiconductor substrate in the first duration T1 time period by adopting an in-situ doping principle, then, in a second duration T2 time period after the end of the first duration T1 time period, the introduction of the reaction gas source into the low-pressure furnace tube is immediately stopped, and the in-tube gas pressure of the low-pressure furnace tube is reduced to a second gas pressure (i.e., the first gas pressure is reduced to 0) from the first gas pressure in the first duration T1 time period, and simultaneously, the residual reaction gas introduced into the low-pressure furnace tube is rapidly reduced to the second gas pressure, and the residual reaction gas in the first duration T1 time period is used for forming a doped polysilicon film with a certain thickness on the surface of the semiconductor substrate, and then, the residual silicon is prevented from forming a film in the first time period due to the deposition of the polysilicon film forming process, and the deposition of the residual silicon film is formed on the surface of the polysilicon film in the first time period.
And then, performing a second cycle, namely performing back pressure treatment on the air pressure in the low-pressure furnace tube to boost the air pressure in the low-pressure furnace tube to the first air pressure state, and introducing the reaction gas with the duration of T1 into the low-pressure furnace tube in the air pressure state again, and then performing depressurization on the air pressure in the low-pressure furnace tube and removal treatment on residual reaction gas and byproducts generated in the process, wherein the cycle operation is performed for a preset number of times, as shown in fig. 2, namely performing a plurality of low-pressure deposition-depressurization air suction byproduct removal cycle processes to obtain the doped polysilicon film after the cycle of the preset number of times is performed.
As an example, the time ratio of the first duration T1 and the second duration T2 ranges from: 3:1-10:1, namely 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1 and the like, and the time ratio is preferably selected to be 5:1 in the embodiment of the invention; the cycle times are as follows: 3-10 times, namely 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times and the like, are circulated, and the preferred embodiment of the invention is to select 5 times of circulation. The first pressure is in the range of 0.1Torr to 3Torr, and in a preferred embodiment of the present invention, the first pressure is set to 0.6Torr, and the second pressure is set to 0Torr.
In addition, in the embodiment of the present invention, since the purpose of forming the phosphorus doped polysilicon film and solving the bulge defect existing on the surface of the phosphorus doped polysilicon film as shown in fig. 3 is to form the phosphorus doped polysilicon film, the mixed gas source is exemplified by a phosphine doped gas source and a silane film gas source. Wherein in the fig. 3, reference numeral 100 is used to designate the semiconductor substrate, and reference numeral 110 is used to designate the doped polysilicon thin film formed on the surface of the semiconductor substrate 100.
It will be appreciated that the semiconductor substrate 100 provided in the 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 100 in this embodiment is, for example, a silicon wafer.
As is apparent from the inventive concept of the embodiment of the present invention, the present invention removes the bulge defect occurring during the gradual formation of the doped polysilicon thin film in stages, however, although the bulge defect may be removed to some extent already during the steps S1 and S2 performed using the above-described multiple cycles provided in the embodiment of the present invention, after the last cycle, the surface of the doped polysilicon thin film formed by stacking may still have a problem that a part of the region is bulged due to the aggregation of the doping elements buried inside into nuclei, and thus the surface polysilicon of the doped polysilicon thin film is bulged, and thus the present invention researchers further provide the contents of the steps S3 and S4 after performing the steps S1 and S2 as described above for a preset number of times in a cycle.
Step S3, as shown in fig. 2, after the second period T2 of the last cycle, the in-tube pressure of the low-pressure furnace tube is rapidly set from the second air pressure to a third air pressure (back pressure treatment), and simultaneously an oxidizing gas, preferably oxygen, is introduced into the low-pressure furnace tube, and the surface of the target doped polysilicon film formed after the steps S1 and S2 are performed for the preset times is subjected to thermal oxidation treatment, wherein the third air pressure is higher than the first air pressure.
As an example, the step S3 is a step of performing a thermal oxidation treatment on the surface of the target doped polysilicon thin film, and includes: the partial thickness surface oxidation of the phosphorus doped polysilicon thin film 110 having the bulge defect as shown in fig. 3 is converted into silicon dioxide 120 as shown in fig. 4.
Step S4, as shown in fig. 4 and 5, performing a cleaning process on the phosphorus doped polysilicon film 110 whose surface is oxidized to the silicon dioxide 120, so as to remove all the silicon dioxide 120 on the surface of the phosphorus doped polysilicon film 110.
As an example, the cleaning solution used in the cleaning process is an acid cleaning solution, and the acid cleaning solution includes hydrofluoric acid HF.
In this embodiment, after the multiple "low pressure deposition-depressurization and air evacuation to remove by-products" cycles consisting of the steps S1 and S2 are adopted, the surface of the doped polysilicon film with the bulge defect on the surface, for example, the surface of the phosphorus doped polysilicon film, may be further subjected to a thermal oxidation treatment to convert the surface polysilicon of the doped polysilicon film and the surface polysilicon with the bulge defect from polysilicon to silicon dioxide, and then the silicon dioxide is removed by a cleaning process using an acid cleaning solution, as shown in fig. 3to 5, i.e., the characteristics of the silicon dioxide can be removed by the thermal oxidation process and the acid cleaning solution, so that the polysilicon in the bulge defect is consumed and the silicon dioxide is removed, as shown in fig. 5, thereby achieving the purpose of effectively removing the bulge defect generated on the surface of the phosphorus doped polysilicon film, and finally improving the yield of the semiconductor device.
It should be noted that, as can be seen from the above-mentioned processes of step S3 and step S4, the method for forming a doped polysilicon thin film according to the embodiment of the present invention, after the doped polysilicon thin film formed by using the steps S1 and S2 of the first cycle is used, needs to convert the silicon dioxide with a partial thickness, that is, the thickness of the doped polysilicon thin film with a partial thickness formed is consumed while removing the polysilicon in the bulge defect, so, in order to avoid the problem that the thickness of the finally formed target doped polysilicon thin film is smaller than the design requirement caused by the steps S3 and S4, the method for forming the embodiment of the present invention needs to determine by combining the thickness of the silicon dioxide after the last conversion and the residual thickness of the doped polysilicon thin film to be 8000 a when the step of dividing the total reaction time of the step S1 of the first cycle is performedThe thickness of the polysilicon to be oxidized and consumed (the thickness of the polysilicon in the doped polysilicon film consumed in the final formation of silicon dioxide) is 200 +.>The total reaction time is 8200 +.>And (5) calculating.
In addition, based on the inventive concept and the inventive steps of the above-mentioned method for forming a doped polysilicon film, the embodiment of the invention further provides a method for removing surface defects of a doped polysilicon film, which at least includes the method for forming a doped polysilicon film, and will not be described in detail herein.
In summary, the present invention provides a method for forming a doped polysilicon film and a method for removing surface defects thereof, which comprises dividing a total time for forming the doped polysilicon film into a plurality of groups of time periods, wherein each group of time periods consists of a first time period and a second time period, then, circulating the LPCVD process for the first time period and the second time period in a low pressure furnace tube, setting the gas pressure in the low pressure furnace tube of the LPCVD process to be low pressure (first gas pressure) and introducing a proper amount of reaction gas source in the first time period, reducing the gas pressure in the low pressure furnace tube from the low pressure to 0 (second gas pressure) in the second time period, simultaneously rapidly discharging the residual reaction gas source and byproducts in the low pressure furnace tube, and then, after the total time period, raising the gas pressure in the low pressure furnace tube back to a normal pressure state (third gas pressure), and introducing an oxidizing gas (oxygen gas) into the low pressure furnace tube, so as to perform a thermal oxidation treatment on the surface of the doped polysilicon film.
The invention adopts a plurality of low-pressure deposition-depressurization air suction byproduct removal cycles, and the reaction is carried out for a certain time in each cycle to form the doped polysilicon film, and then redundant reaction gas and byproduct removal are carried out on the doped polysilicon film immediately, so that the problem of bulge defect on the surface of the doped polysilicon film (such as a phosphorus doped polysilicon film) caused by aggregation of doping elements (such as phosphorus elements) is solved in a plurality of stages in the film formation process.
And after the repeated 'low-pressure deposition-depressurization and air extraction byproduct removal' circulation, further utilizing a thermal oxidation process to convert the bulge defects existing on the surface of the formed doped polysilicon film into silicon dioxide, namely consuming at least part of polysilicon in the bulge defects, and then utilizing an acidic cleaning solution to remove the silicon dioxide, thereby achieving the purpose of effectively removing the bulge defects generated on the surface of the phosphorus doped polysilicon film and finally improving the yield of semiconductor devices.
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 (8)

1. A method for forming a doped polysilicon thin film, which is suitable for an LPCVD process using a low pressure furnace tube as a reaction apparatus, comprising:
step S1, a semiconductor substrate is placed in the low-pressure furnace tube, and under the condition that the pressure in the low-pressure furnace tube is set to be a first pressure, a reaction gas source with a first duration is introduced into the low-pressure furnace tube, wherein the reaction gas source comprises a doping gas source and a film gas source, and a doped polycrystalline silicon film with partial thickness is formed on the surface of the semiconductor substrate in a mode of utilizing an LPCVD process and simultaneously carrying out in-situ doping;
step S2, stopping introducing the reaction gas source after the first duration, and introducing an exhaust gas source for a second duration into the low-pressure furnace tube under the condition that the pressure in the low-pressure furnace tube is set to be a second pressure so as to at least remove the residual reaction gas source in the low-pressure furnace tube, wherein the first pressure is higher than the second pressure;
step S3, after the second time period, sequentially returning to execute the step S1 and the step S2 until the preset times are circularly executed, setting the in-tube pressure of the low-pressure furnace tube to be a third air pressure, simultaneously introducing oxidizing gas into the low-pressure furnace tube, and performing thermal oxidation treatment on the surface of the target doped polysilicon film formed after the preset times of the step S1 and the step S2 are executed, wherein the third air pressure is higher than the first air pressure;
the target doped polysilicon film is a phosphorus doped polysilicon film, wherein the surface of the phosphorus doped polysilicon film has bulge defects, and the bulge defects comprise polysilicon;
the step S3 of performing a thermal oxidation treatment on the surface of the target doped polysilicon thin film includes: oxidizing and converting part of the thickness surface of the phosphorus doped polysilicon film with the bulge defect into silicon dioxide; and, after the step S3, the forming method further includes: and S4, performing a cleaning process on the phosphorus-doped polysilicon film with the surface oxidized into the silicon dioxide so as to remove all the silicon dioxide on the surface of the phosphorus-doped polysilicon film.
2. The method of forming a doped polysilicon film according to claim 1, wherein the time ratio of the first duration to the second duration ranges from: 3:1 to 10:1.
3. The method of forming a doped polysilicon thin film according to claim 1, wherein the semiconductor substrate sequentially performs the steps S1 and S2 a preset number of times as follows: 3 times to 10 times.
4. The method of claim 1, wherein the first gas pressure is in a range of 0.1Torr to 3Torr, the second gas pressure is 0Torr, and the third gas pressure is atmospheric pressure.
5. The method of forming a doped polysilicon film according to claim 4, wherein the reactive gas source comprises silane gas and the dopant gas source comprises phosphine gas.
6. The method of forming a doped polysilicon film of claim 5, wherein the source of exhaust gas comprises nitrogen and the oxidizing gas comprises oxygen.
7. The method of forming a doped polysilicon film of claim 1, wherein the cleaning solution used in the cleaning process is an acid cleaning solution, and the acid cleaning solution comprises hydrofluoric acid.
8. A surface defect removal method for a doped polysilicon film, comprising the method for forming a doped polysilicon film according to any one of claims 1to 7.
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