A surface treatment process for a wafer

Abstract

The application discloses a wafer surface treatment process, which comprises the following steps: S1, providing a pre-cleaning cavity, and conveying a wafer into the pre-cleaning cavity; S2, pre-cleaning the wafer by introducing a pre-cleaning gas into the pre-cleaning cavity, and removing an oxide layer on the wafer surface; and S3, conveying the pre-cleaned wafer into an epitaxial reaction cavity, and re-treating the wafer by introducing a surface re-treatment gas, so as to remove polysilicon and / or undulation on the wafer surface, wherein the process temperature of the re-treatment is 600-950 DEG C. By removing the polysilicon and / or undulation on the wafer surface in the re-treatment process, and by performing the re-treatment and the epitaxial process in the same cavity, wafer warping and deformation are avoided, the wafer is not exposed again to generate an oxide layer when being taken out of the cavity, the surface treatment quality is ensured, the process time is greatly shortened, and energy loss in the re-treatment process is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductor wafers, and particularly relates to a wafer surface treatment process. BACKGROUND

[0002] Silicon substrate (silicon wafer) as the most important semiconductor material plays an irreplaceable role in the information industry, but it has the shortcomings of low carrier mobility and slow device speed, and needs to be epitaxially grown with other materials to solve the problem. At present, most high-precision wafer surfaces usually include multiple parts, such as a silicon substrate and a dielectric material (such as silicon nitride or silicon oxide), and it is usually desired to epitaxially grow on the silicon substrate but not on the dielectric material to achieve the purpose of "selective epitaxy". However, in the actual process, polycrystalline silicon or polycrystalline germanium silicon is often grown on the dielectric material.

[0003] In the prior art, the polycrystalline silicon or polycrystalline germanium silicon on the surface of the dielectric material needs to be removed, and the conventional process method is high-temperature annealing, but this method has the following defects: long-time high-temperature annealing process, wafer warping deformation, affecting the quality of the wafer.

[0004] Therefore, there is an urgent need for a wafer surface treatment process that does not cause deformation of the wafer during the treatment process, improves the quality and efficiency of wafer surface treatment. SUMMARY

[0005] The purpose of the present application is to overcome the defect that the wafer is prone to warping deformation during long-time high-temperature annealing, remove the polycrystalline silicon-containing material and / or undulations on the surface of the wafer, and enhance the effect of wafer surface treatment, which is conducive to improving the quality of the subsequent epitaxial layer formation.

[0006] In order to achieve the above purpose, the present application provides a wafer surface treatment process, which comprises the following steps: S1, providing a pre-cleaning cavity, and conveying a wafer into the pre-cleaning cavity; S2, introducing a pre-cleaning gas into the pre-cleaning cavity to pre-clean the wafer and remove the oxide layer on the surface of the wafer; S3, conveying the pre-cleaned wafer into an epitaxial reaction cavity, and introducing a surface re-treatment gas to re-treat the wafer to remove the polycrystalline silicon-containing material and / or undulations on the surface of the wafer, wherein the process temperature of the re-treatment is 600-950℃.

[0007] Optionally, in step S2, the process temperature of the pre-cleaning is 100-160℃.

[0008] Optionally, the pre-cleaning gas at least comprises a fluorine-containing gas, a nitrogen-hydrogen-containing gas and a rare gas.

[0009] Optionally, the fluorine-containing gas comprises any one or a combination of more than two of hydrogen fluoride (HF), carbon tetrafluoride (CF4), trifluoromethane (CHF3), difluoromethane (CH2F2), fluoromethane (CH3F), nitrogen trifluoride (NF3), sulfur hexafluoride (SF6).

[0010] Optionally, the nitrogen-containing hydrogen gas comprises ammonia (NH3) and / or hydrazine (N2H4).

[0011] Optionally, the fluorine-containing gas is hydrogen fluoride (HF), the nitrogen-containing hydrogen gas is ammonia (NH3), and the rare gas is argon (Ar).

[0012] Optionally, the flow rate of the fluorine-containing gas is 30-60 sccm, the flow rate of the nitrogen-containing hydrogen gas is 30-60 sccm, and the flow rate of the rare gas is 200-1500 sccm.

[0013] Optionally, the surface re-treatment gas can react with the polycrystalline silicon-containing substance and / or the relief on the wafer surface to generate gaseous volatile substances.

[0014] Optionally, the surface re-treatment gas is composed of a chlorine-containing gas and a carrier gas.

[0015] Optionally, the chlorine-containing gas comprises chlorine (Cl2).

[0016] Optionally, the carrier gas is argon.

[0017] Optionally, in step S3, the re-treatment time is 100-350 s, and the ratio of the flow rate of the carrier gas to the flow rate of the chlorine-containing gas is 150:1-400:1.

[0018] Optionally, the flow rate of the chlorine-containing gas is 100-400 sccm, the flow rate of the argon is 20000-40000 sccm, and the re-treatment process temperature is 600-750℃.

[0019] Optionally, the surface re-treatment gas is non-plasma.

[0020] Optionally, the surface treatment process further comprises a step of performing epitaxial treatment on the wafer in the epitaxial reaction chamber, the epitaxial treatment being performed after step S3, and the process temperature of the epitaxial treatment being 600-980℃.

[0021] Advantages of the present application:

[0022] (1) the wafer surface reprocessing process of the present application is carried out in the epitaxial reaction cavity, chlorine-containing gas is introduced to be adsorbed on the wafer surface, silicon dichloride gaseous volatile is generated, thereby removing the polycrystal and undulation on the wafer surface, the process temperature of the wafer surface reprocessing process is 600-750℃, therefore the adsorption of chlorine-containing gas on the wafer surface can be promoted quickly, the process time is maintained short, the reprocessing process can be completed in 100-350s, the short time can prevent the wafer surface from being damaged by excessive reaction of chlorine, the wafer warping deformation caused by long time high temperature annealing is avoided, and the wafer surface treatment quality is ensured. In addition, the chlorine-containing gas is chlorine, the gas does not contain other elements, thereby avoiding the introduction of other elements to cause other reactions.

[0023] (2) further, the reprocessing gas is in a non-plasma state, which can prevent the wafer surface from being uneven due to the physical bombardment of plasma, thereby affecting the subsequent epitaxial quality.

[0024] (3) further, the surface reprocessing process is carried out in the epitaxial reaction cavity, therefore when the epitaxial treatment process is carried out after the surface reprocessing process is completed, the wafer does not need to be moved, thereby avoiding the wafer from being exposed again to generate an oxide layer; in addition, the temperature of the epitaxial treatment process is high, and the temperature difference with the reprocessing process is small, the epitaxial treatment process can be carried out only after a short heating time after the reprocessing process, thereby shortening the process time, providing a thermal basis for the wafer epitaxial reaction, avoiding energy loss, and ensuring the quality of the epitaxial layer formation.

[0025] (4) the present application further comprises removal of the natural oxide layer before the reprocessing process, fluorine-containing gas and nitrogen-containing hydrogen gas are introduced into the pre-cleaning cavity, the fluorine-containing gas and the nitrogen-containing hydrogen gas react with the natural oxide layer on the wafer surface to generate an amino complex, at the same time the amino complex sublimates, the natural oxide layer on the wafer surface is removed through the pre-cleaning step, and the removal of the oxide layer can prepare for the next reprocessing. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 a flow chart of a wafer surface treatment process of the present application.

[0027] Figure 2 a state schematic diagram of a wafer surface treatment process of the present application.

[0028] Figure 3 a structure schematic diagram of a wafer surface pre-cleaning device of the present application.

[0029] Figure 4 a structure schematic diagram of a wafer surface epitaxial reaction device of the present application.

[0030] In the figure, 101-chamber wall, 102-cover, 104-base, 105-pre-cleaning cavity, 106-tail gas passage, 107-tail gas interface, 109-lifting device, 110-pin, 111-inner liner, 112-lower passage, 113-upper passage, 121-second passage, 122-first passage, 123-remote plasma, 131-first diffusion plate, 133-second diffusion plate.

[0031] 200-epitaxial reaction chamber, 201-heating assembly, 202-temperature measuring instrument, 204-wafer, 205-base, 206-exhaust port, 208-lower dome, 209-rotary support shaft, 210-supporting bracket, 211-pin, 213-gas inlet, 214-process gas, 215-preheating ring, 216-upper dome. DETAILED DESCRIPTION

[0032] The technical solutions of the present application will be described clearly and completely below in combination with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0033] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0034] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection; it can be direct connection, or indirect connection through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0035] For the polycrystallization and undulation of the wafer surface, the common treatment method is to perform high-temperature annealing, but during the long-time high-temperature annealing process, the wafer will be deformed in some warping, thereby affecting the quality of the wafer, and at the same time, it consumes a long time and prolongs the processing cycle.

[0036] The present application carries out a pre-cleaning process on the wafer surface, and then carries out a reprocessing process, selects a specific reprocessing process temperature, flow, gas state and time, so that the polycrystal and the relief on the wafer surface are quickly removed without an annealing step. At the same time, the reprocessing and epitaxial processes are carried out in the same chamber. When the reprocessing process is completed, the next process can be realized without moving the wafer, avoiding the oxidation layer generated by the wafer being exposed again, greatly saving the process time, and avoiding the energy waste caused by high temperature in the surface reprocessing. The following will be described in detail in combination with the drawings.

[0037] As shown in Figure 1 The wafer surface treatment process provided by the present application comprises the following steps:

[0038] S1, providing a pre-cleaning chamber, and conveying the wafer into the pre-cleaning chamber.

[0039] In some embodiments, a purge process can be carried out on at least one place in the pre-cleaning chamber before step S1. The at least one place is the susceptor or the chamber wall of the pre-cleaning chamber. The timing and quantity of purging the susceptor or the chamber wall can be controlled by controlling the direction of the outlet of the purge gas pipeline.

[0040] In some embodiments, in the purge process, in order to avoid the influence of the residue of the purge gas on the subsequent process, the purge gas is an inert gas or a reducing gas, and at least one of argon (Ar), helium (He), nitrogen (N2) and hydrogen (H2) is selected, preferably argon (Ar).

[0041] S2, introducing a pre-cleaning gas into the pre-cleaning chamber to pre-clean the wafer and remove the oxidation layer on the wafer surface.

[0042] After the pre-cleaning gas is introduced, the oxidation layer on the wafer surface adsorbs the pre-cleaning gas and reacts with the pre-cleaning gas to generate an amino complex. At the same time, the amino complex sublimates at the temperature in the pre-cleaning chamber, thereby removing the oxidation layer on the wafer surface. The pre-cleaning gas comprises a fluorine-containing gas, a nitrogen-hydrogen-containing gas and a noble gas. The fluorine-containing gas and the nitrogen-hydrogen-containing gas are used as special gases, and the noble gas is used as a carrier gas.

[0043] The pre-cleaning process is specifically: the process temperature of the pre-cleaning is controlled to be 100-160℃, the fluorine-containing gas is mixed with the noble gas and introduced into the pre-cleaning chamber, the nitrogen-hydrogen-containing gas is mixed with the noble gas and introduced into the pre-cleaning chamber, the gas flow of the fluorine-containing gas is 10-100sccm, the gas flow of the nitrogen-hydrogen-containing gas is 10-100sccm, and the gas flow of the noble gas is 200-1500sccm. As Figure 2As shown, the oxide layer on the wafer surface reacts with the fluorine-containing gas and the nitrogen-containing hydrogen gas to form an amino complex. During the pre-cleaning process, the generated amino complex gradually volatilizes, thereby continuously removing the oxide layer on the wafer surface. After the oxide layer on the wafer surface is completely removed, the wafer is transferred out of the pre-cleaning chamber for the next process.

[0044] The fluorine-containing gas includes any one or a combination of more than two of hydrogen fluoride (HF), carbon fluoride (CF4), trifluoromethane (CHF3), difluoromethane (CH2F2), fluoromethane (CH3F), nitrogen trifluoride (NF3), and sulfur hexafluoride (SF6). The nitrogen-containing hydrogen gas includes ammonia (NH3) and / or diimide (N2H4). The rare gas includes any one or a combination of more than two of argon (Ar), helium (He), and xenon (Xe).

[0045] In some embodiments, the fluorine-containing gas is hydrogen fluoride, the nitrogen-containing hydrogen gas is ammonia, and the rare gas is argon. According to step S2 of the present application, the fluorine-containing gas is adsorbed to the wafer surface and reacts with the nitrogen-containing hydrogen gas to form an easily sublimable amino complex. After the amino complex sublimates, the oxide layer on the wafer surface is removed.

[0046] In some embodiments, the gas flow of the fluorine-containing gas is 30-60 sccm, the gas flow of the nitrogen-containing hydrogen gas is 30-60 sccm, and the gas flow of the rare gas is 400-1000 sccm.

[0047] In some embodiments, the fluorine-containing gas and the rare gas are mixed and then introduced into the pre-cleaning chamber through the second pipeline, the nitrogen-containing hydrogen gas and the rare gas are mixed and then introduced into the pre-cleaning chamber through the first pipeline, and the fluorine-containing gas and the nitrogen-containing hydrogen gas are mixed in the pre-cleaning chamber. The fluorine-containing gas and the nitrogen-containing hydrogen gas are mixed and reacted for a short time. After the fluorine-containing gas and the nitrogen-containing hydrogen gas are introduced into the pre-cleaning chamber through different pipelines, the gases are mixed in the pre-cleaning chamber. Therefore, the rate of gas mixing reaction or the time of gas introduction does not need to be considered, and the fluorine-containing gas and the nitrogen-containing hydrogen gas can be continuously introduced into the reaction chamber.

[0048] S3, the pre-cleaned wafer is transferred into an epitaxial reaction chamber, a surface re-treatment gas is introduced to re-treat the wafer to remove polysilicon and / or undulations on the wafer surface. The process temperature of the re-treatment is 600-950°C.

[0049] The surface re-treatment gas is composed of a chlorine-containing gas and a carrier gas, and does not include other gases. The chlorine-containing gas includes chlorine (Cl2), and the carrier gas is argon. As Figure 2As shown, the surface reprocessing gas can be adsorbed with the polysilicon and / or the hillocks at high temperature to form silicon dichloride gaseous volatile, and the polysilicon and the hillocks on the wafer surface are removed after the gaseous volatile is volatilized. The chlorine-containing gas is chlorine, which avoids bringing other elements such as hydrogen, and hydrogen can generate water with residual oxygen, which is fatal to high aspect ratio devices and can cause failure of subsequent epitaxial processing; and the carrier gas is argon, which also avoids gases such as hydrogen and nitrogen that are prone to reaction, and argon can well increase the flow rate of chlorine.

[0050] In some embodiments, the surface reprocessing time is 100-350 s, and the flow rate ratio of the carrier gas to the chlorine-containing gas is 150:1-400:1. The flow rate of the carrier gas is at least 150 times that of the chlorine-containing gas, which can accelerate the flow speed of the chlorine-containing gas, thereby accelerating the adsorption of the surface reprocessing gas and the polysilicon and / or the hillocks on the wafer surface and accelerating the removal of the gaseous volatile.

[0051] In some embodiments, in step S3, the flow rate of the chlorine-containing gas in the surface reprocessing gas is 100-400 sccm, the flow rate of the argon is 20,000-40,000 sccm, and the surface reprocessing process temperature is 600-750°C. Since the reprocessing step is used in step S3, after the wafer ends the pre-cleaning step in the pre-cleaning cavity of the pre-cleaning device, the wafer is transferred into the epitaxial reaction cavity of the epitaxial reaction device, and no annealing step is required after step S3, which can avoid the wafer warping deformation after experiencing long-time high-temperature annealing, thereby ensuring the processing quality of the wafer surface to facilitate subsequent epitaxial processes.

[0052] In some embodiments, the surface reprocessing gas is non-plasma, which can prevent the wafer surface from being uneven due to the bombardment of plasma, affecting the subsequent epitaxial quality. In addition, plasma cannot be generated in the epitaxial reaction cavity, and plasma cannot be used at a temperature above 600°C. In the present application, the surface reprocessing uses a process temperature of 600-750°C, which can provide a thermal basis for the next epitaxial processing of the wafer.

[0053] In some embodiments, after the step S3, the method further comprises epitaxial processing the wafer in the epitaxial chamber, wherein the epitaxial processing has a process temperature of 600-980 °C, and the epitaxial processing uses a process gas comprising a silicon-containing gas and a germanium-containing gas, wherein the silicon-containing gas comprises one or more of SiH4, SiHCl3, SiH2Cl2, SiCl4, and the germanium-containing gas comprises one or both of GeH4and Ge2H6. After the removal of the polycrystalline silicon-containing material and / or the relief on the surface of the wafer, the wafer does not need to be removed from the chamber, and after the process temperature of the epitaxial chamber is adjusted to the process temperature of the epitaxial processing, the epitaxial processing can be directly performed. This operation has the advantage of avoiding the wafer being exposed again to generate an oxide layer when the wafer is removed from the chamber. In addition, the process temperature of the epitaxial processing is higher, and the difference between the process temperature of the epitaxial processing and the process temperature of the reprocessing is small, so that after the reprocessing step is completed, only a short heating time is needed to perform the epitaxial processing, which shortens the process time and reduces the heat loss.

[0054] In some embodiments, after the step S3, the method further comprises a secondary purging step, wherein the secondary purging step comprises a step of purging the susceptor, the chamber, and / or the sidewall of the chamber with one or more of helium (He), argon (Ar), xenon (Xe), hydrogen (H2), and nitrogen (N2).

[0055] Optionally, the wafer in the surface treatment process is a silicon wafer.

[0056] Figure 3A schematic diagram of a pre-cleaning device for pre-cleaning a wafer is shown, which is used for pre-cleaning the surface of the wafer in step S2, and removing the oxide layer on the surface of the wafer. The pre-cleaning device comprises a pre-cleaning chamber 105, which comprises a chamber wall 101, a lifting device 109, a susceptor 104, a remote plasma 123, a pin 110 and an inner liner 111. A lid 102 is arranged above the pre-cleaning chamber 105, and the remote plasma 123 is arranged above the top of the lid 102. The lifting device 109 is arranged at the bottom of the pre-cleaning chamber 105, and the susceptor 104 is arranged at the top of the lifting device 109. The susceptor 104 is used to support the wafer, and the height of the susceptor 104 can be adjusted by the lifting device 109. For example, the susceptor 104 can be lowered, and the wafer can be separated from the susceptor 104 under the support of the pin 110, so that the wafer can be easily taken by a robot. The inner liner 111 is arranged around the susceptor 104, and is used to uniformly pump the pre-cleaning gas out of the pre-cleaning chamber 105. The annular outer surface of the inner liner 111 is provided with an upper passage 113 and a lower passage 112, and a plurality of air holes are arranged on the inner liner at the upper passage 113, which are arranged in an annular manner. The pre-cleaning chamber 105 further comprises a first passage 122, a second passage 121 and a shower head. The shower head is arranged between the remote plasma 123 and the pre-cleaning chamber 105, and is used to make the pre-cleaning gas entering the pre-cleaning chamber 105 more uniformly diffuse. The shower head comprises a first diffusion plate 131 and a second diffusion plate 133, both of which are provided with through holes. The first diffusion plate 131 is arranged above the second diffusion plate 133, and an air uniformization space is arranged between the first diffusion plate 131 and the second diffusion plate 133. During the process, the first pre-cleaning gas (such as nitrogen-containing hydrogen gas) is introduced into the pre-cleaning chamber 105 through the first passage 122. The first pre-cleaning gas is excited by the remote plasma 123 to form a plasma, and is uniformly introduced into the pre-cleaning chamber 105 through the first diffusion plate 131 and the second diffusion plate 133. The second pre-cleaning gas (such as fluorine-containing gas) is introduced into the pre-cleaning chamber 105 through the second passage 121, and is uniformly introduced into the pre-cleaning chamber 105 through the second diffusion plate 133. The first and second pre-cleaning gases diffuse to the upper surface of the wafer, react with the oxide layer on the surface of the wafer, sublimate after the reaction, and thus remove the oxide layer on the surface of the wafer.

[0057] After the pre-cleaning is completed, the pre-cleaning gas is discharged through the venting holes on the inner liner 111, the upper channel 113, the lower channel 112, the tail gas channel 106 and the tail gas interface 107 by the action of the pump. After the pre-cleaning is completed, the height of the pedestal 104 is lowered by the lifting device 109, at this time the pin 110 supports the wafer, thereby separating the pedestal 104 from the wafer, and then the wafer is lifted by the robot and transferred out of the pre-cleaning device, thereby completing the whole pre-cleaning process.

[0058] Figure 4 The structure of the epitaxial reaction device for surface re-treatment and epitaxial treatment of the wafer is shown in the schematic diagram of the epitaxial reaction device of the present application, which is used for the re-treatment of the wafer surface and the subsequent epitaxial treatment in step S3. The epitaxial reaction device comprises an epitaxial reaction chamber 200, which comprises a chamber, a pedestal 205, a pedestal support device (a rotating support shaft 209, a support bracket 210, a pin 211), a preheating ring 215, a heating assembly 201. The heating assembly 201 is arranged above and below the chamber. The chamber comprises an upper dome 216, a lower dome 208 and a sidewall, the upper dome 216 is arranged above the sidewall, and the lower dome 208 is arranged below the sidewall, both the upper dome 216 and the lower dome 208 are made of quartz, which can make the infrared heat radiation of the heating assembly 201 enter the chamber to provide heating energy; the pedestal 205 is located inside the chamber and used for carrying the wafer 204; the rotating support shaft 209 is connected with the pedestal 205 and used for supporting the up-down movement and the rotating movement of the pedestal 205; the support bracket 210 is used for supporting the wafer 204 by the pin 211 when the rotating support shaft 209 is lowered, thereby separating the wafer 204 from the pedestal 205 and taking out the wafer 204; the preheating ring 215 is used for preheating the re-treatment gas or the process gas during the epitaxial treatment entering the chamber; the epitaxial reaction chamber 200 further comprises a temperature measuring instrument 202 for monitoring the temperature near the wafer 204; the epitaxial reaction chamber 200 further has a gas inlet 213 and an exhaust port 206 arranged opposite to the gas inlet. The re-treatment gas or the process gas 214 during the epitaxial treatment is introduced into the epitaxial reaction chamber 200 from the gas inlet pipe of the gas inlet 213, passes through the surface of the wafer 204, and the gas reacts with the polycrystalline silicon-containing substance and / or the undulation on the surface of the wafer 204, thereby removing the polycrystalline silicon-containing substance and / or the undulation on the surface of the wafer 204 or forming an epitaxial layer on the wafer surface during the epitaxial treatment, and the treated gas is discharged from the exhaust port 206 by the suction force of the pump connected with the exhaust port 206.

[0059] Embodiment

[0060] The specific working steps of the wafer surface treatment process using the pre-cleaning device and the epitaxial reaction device of the present application are as follows:

[0061] 1) providing a pre-cleaning device, the pre-cleaning device comprising a pre-cleaning chamber, and transferring a silicon wafer to be processed into the pre-cleaning chamber, and placing the silicon wafer to be processed on a susceptor;

[0062] 2) purging step: purging the susceptor in the pre-cleaning chamber with argon (Ar), the pressure in the pre-cleaning chamber is 5 Torr, and the purging time is 10 s; purging the inner wall of the pre-cleaning chamber with argon (Ar), the pressure in the pre-cleaning chamber is 5 Torr, and the purging time is 10 s; keeping the pre-cleaning chamber clean;

[0063] 3) purging the pre-cleaning chamber with a pre-cleaning gas to pre-clean the silicon wafer, and removing the oxide layer on the surface of the silicon wafer, the process temperature of the pre-cleaning is 100℃;

[0064] Hydrogen fluoride (HF) gas and an appropriate amount of rare gas argon (Ar) are mixed and then introduced into the pre-cleaning chamber from the second pipeline, and hydrogen nitride gas ammonia (NH3) and an appropriate amount of rare gas argon (Ar) are mixed and then introduced into the pre-cleaning chamber from the first pipeline. The flow rate of the hydrogen fluoride (HF) gas is 30 sccm, the flow rate of the ammonia (NH3) gas is 30 sccm, and the flow rate of the argon (Ar) is 400 sccm. The oxide layer on the surface of the silicon wafer reacts with the introduced fluorine-containing gas and nitrogen-containing hydrogen gas to form volatile amino complex (NH4)2SiF6, and at the same time, the amino complex volatilizes to remove the oxide layer on the surface of the silicon wafer;

[0065] 4) pumping the pre-cleaning chamber to a certain pressure to remove the residual gas;

[0066] 5) providing an epitaxial reaction device, the epitaxial reaction device comprising an epitaxial reaction chamber, transferring the pre-cleaned silicon wafer into the epitaxial reaction chamber, and introducing surface reprocessing gas chlorine (Cl2) and argon (Ar) to reprocess the silicon wafer to remove polysilicon on the surface of the silicon wafer and / or undulations, wherein the process temperature of the reprocessing is 650℃, the reprocessing gas is non-plasma, the flow rate of chlorine is controlled to be 100 sccm, the flow rate of argon is 20000 sccm, and the reprocessing time is 180 s;

[0067] 6) after completing the surface reprocessing of the silicon wafer, increasing the process temperature in the epitaxial reaction chamber to 690℃, without taking the wafer out of the chamber, and introducing epitaxial processing process gas to perform epitaxial processing on the silicon wafer; wherein the process gas is silane and germane.

[0068] 7) secondary purging step: purging the inner part of the epitaxial reaction chamber with gas, in this embodiment, the gas is argon (Ar), the purging time is 50 s, the pressure in the epitaxial reaction chamber is 5 Torr, and the epitaxial reaction chamber is kept clean.

[0069] In summary, the present application provides a wafer surface treatment process. After removing the natural oxide layer in the pre-cleaning cavity, the polycrystal and / or the relief on the wafer surface are removed by setting the specific gas and the temperature, flow rate, state (i.e. non-plasma state), time of the reprocessing process conditions. The reprocessing and epitaxial process of the present application are both performed in the same cavity, without the need for long time high temperature annealing process, avoiding the wafer from warping and deforming, preventing the wafer surface from generating another oxide layer due to the cavity, ensuring the quality of the surface treatment, greatly shortening the process time, and being conducive to reducing the energy loss in the process.

[0070] Although the present application has been described in detail by the above preferred embodiments, it should be recognized that the above description should not be considered as limiting the present application. Various modifications and substitutions will be apparent to those skilled in the art after reading the above description. Therefore, the scope of the present application should be defined by the appended claims.

Claims

1. A surface treatment process for wafers, characterized in that, The surface treatment process includes the following steps: S1 provides a pre-cleaning chamber into which the wafer is transferred; S2, a pre-cleaning gas is introduced into the pre-cleaning chamber to pre-clean the wafer and remove the oxide layer on the wafer surface; the pre-cleaning gas contains at least a fluorine-containing gas, a nitrogen-hydrogen-containing gas, and a rare gas; S3, the pre-cleaned wafer is transferred into the epitaxial reaction chamber, and a surface reprocessing gas is introduced to reprocess the wafer to remove polycrystalline silicon-containing materials and undulations on the wafer surface. The reprocessing temperature is 600~950℃; the surface reprocessing gas consists of chlorine-containing gas and carrier gas; the reprocessing time is 100~350s; the flow rate ratio of carrier gas to chlorine-containing gas is 150:1~400:1; and the pressure in the epitaxial reaction chamber is 5 Torr.

2. The surface treatment process as described in claim 1, characterized in that, In step S2, the pre-cleaning process temperature is 100~160℃.

3. The surface treatment process as described in claim 1, characterized in that, The fluorine-containing gas includes any one or any combination of two or more of the following: hydrogen fluoride (HF), carbon fluoride (CF4), trifluoromethane (CHF3), difluoromethane (CH2F2), fluoromethane (CH3F), nitrogen trifluoride (NF3), and sulfur hexafluoride (SF6).

4. The surface treatment process as described in claim 1, characterized in that, The nitrogen-containing hydrogen gas includes ammonia (NH3) and / or diammonium (N2H4).

5. The surface treatment process as described in claim 1, characterized in that, The fluorine-containing gas is hydrogen fluoride (HF), the nitrogen-containing hydrogen gas is ammonia (NH3), and the rare gas is argon (Ar).

6. The surface treatment process as described in claim 1, characterized in that, The flow rate of fluorine-containing gases is 30~60 sccm, the flow rate of nitrogen- and hydrogen-containing gases is 30~60 sccm, and the flow rate of rare gases is 200~1500 sccm.

7. The surface treatment process as described in claim 1, characterized in that, The surface reprocessing gas can react with polycrystalline silicon-containing materials and / or undulations on the wafer surface to generate gaseous volatiles.

8. The surface treatment process as described in claim 1, characterized in that, The chlorine-containing gas includes chlorine (Cl2).

9. The surface treatment process as described in claim 1, characterized in that, The carrier gas is argon.

10. The surface treatment process as described in claim 5, characterized in that, The flow rate of the chlorine-containing gas is 100~400 sccm, the flow rate of the argon gas is 20000 sccm~40000 sccm, and the reprocessing temperature is 600~750℃.

11. The surface treatment process as described in claim 1, characterized in that, The surface reprocessing gas is non-plasma.

12. The surface treatment process as described in claim 1, characterized in that, The surface treatment process further includes the step of: performing epitaxial treatment on the wafer in the epitaxial reaction chamber, wherein the epitaxial treatment is performed after step S3, and the process temperature of the epitaxial treatment is 600~980℃.

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