Method and system for preparing epitaxial wafer and epitaxial wafer

Abstract

The invention relates to a method for preparing an epitaxial wafer, a system for preparing the epitaxial wafer and the epitaxial wafer. The method comprises the following steps: depositing a film layer with a preset thickness on a base of epitaxial growth equipment; and epitaxial growth is carried out on the wafer borne on the base where the film layer is formed so as to obtain an epitaxial wafer, and the preset thickness is determined according to the difference value between the target ERO to be achieved after the wafer is subjected to epitaxial growth and the initial ERO before the wafer is subjected to epitaxial growth. Through the method and the system, the flatness of the epitaxial wafer can reach an expected level under the condition that other quality parameters such as resistivity and thickness of the epitaxial wafer are not influenced.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of semiconductor manufacturing, and in particular, to a method for preparing an epitaxial wafer, a system for preparing an epitaxial wafer, and an epitaxial wafer. BACKGROUND

[0002] An epitaxial wafer is a kind of semiconductor material in which a specific monocrystalline thin film is grown on a substrate wafer through an epitaxial process. Such material is widely used in microelectronics and optoelectronics due to its characteristics such as few surface defects, excellent crystallinity, and controllable resistivity.

[0003] The flatness of an epitaxial wafer is an important parameter for measuring its quality. With the rapid development of semiconductor process technology, higher requirements are put forward for the flatness of epitaxial wafers. In order to obtain an epitaxial wafer with a desired level of flatness, in the related art, the process recipe of the epitaxial growth process experienced by the wafer when forming the epitaxial wafer is adjusted.

[0004] However, the adjustment of the process recipe often has an impact on other quality parameters of the epitaxial wafer such as resistivity and thickness. SUMMARY

[0005] This section provides a general summary of the present disclosure, rather than a comprehensive disclosure of the full scope or all features of the present disclosure.

[0006] The purpose of the present disclosure is to provide a method and system for preparing an epitaxial wafer, by which the flatness of the epitaxial wafer can reach a desired level without affecting other quality parameters such as resistivity and thickness of the epitaxial wafer.

[0007] To achieve the above-mentioned purpose, according to an aspect of the present disclosure, a method for preparing an epitaxial wafer is provided, which comprises: depositing a film layer with a predetermined thickness on a susceptor of an epitaxial growth device; and carrying out epitaxial growth on a wafer carried on the susceptor on which the film layer has been formed to obtain an epitaxial wafer, wherein the predetermined thickness is determined according to a difference between a target ERO to be reached by the wafer after the epitaxial growth and an initial ERO before the epitaxial growth.

[0008] In some embodiments, the film layer with the predetermined thickness can be obtained by controlling at least one of a deposition time and a deposition temperature of the film layer.

[0009] In some embodiments, the at least one can be determined according to an interval in which the initial ERO is located, wherein the interval is one of a plurality of intervals obtained by classifying the initial ERO according to the target ERO in a case where the target ERO is a range of values.

[0010] In some embodiments, the numerical range can be -10 nm to 5 nm.

[0011] In some embodiments, depositing the film layer to form a predetermined thickness on the susceptor of the epitaxial growth apparatus can be performed after completing cleaning of the epitaxial growth apparatus.

[0012] In some embodiments, the predetermined thickness can be in a range of 2 pm to 3 pm.

[0013] According to another aspect of the present disclosure, a method for preparing an epitaxial wafer is provided, comprising: depositing a film layer to form a predetermined thickness on a susceptor of an epitaxial growth apparatus with at least one of a predetermined deposition time and a predetermined deposition temperature; and performing epitaxial growth on a wafer carried on the susceptor on which the film layer has been formed to obtain an epitaxial wafer, wherein the at least one is determined according to a difference between a target ERO to be reached by the wafer after the epitaxial growth and an initial ERO before the epitaxial growth.

[0014] According to yet another aspect of the present disclosure, a system for preparing an epitaxial wafer is provided, comprising: a growth unit configured to deposit a film layer to form a predetermined thickness on a susceptor of an epitaxial growth apparatus, and perform epitaxial growth on a wafer carried on the susceptor on which the film layer has been formed to obtain an epitaxial wafer; and a processing unit configured to determine the predetermined thickness according to a difference between a target ERO to be reached by the wafer after the epitaxial growth and an initial ERO before the epitaxial growth.

[0015] According to still another aspect of the present disclosure, a system for preparing an epitaxial wafer is provided, comprising: a growth unit configured to deposit a film layer to form a predetermined thickness on a susceptor of an epitaxial growth apparatus with at least one of a predetermined deposition time and a predetermined deposition temperature, and perform epitaxial growth on a wafer carried on the susceptor on which the film layer has been formed to obtain an epitaxial wafer; and a processing unit configured to determine the at least one according to a difference between a target ERO to be reached by the wafer after the epitaxial growth and an initial ERO before the epitaxial growth.

[0016] According to yet another aspect of the present disclosure, an epitaxial wafer is provided, which is prepared according to the method for preparing an epitaxial wafer of any of the above embodiments, and has an SFQR≤20 nm and an ESFQR≤25 nm.

[0017] In some embodiments, the epitaxial wafer can have an ERO in a range of -10 nm to 5 nm.

[0018] According to the above technical solution, the SFQR and the ESFQR of the epitaxial wafer are simultaneously brought to the respective desired levels by bringing the ERO of the epitaxial wafer to a range, thereby bringing the flatness of the epitaxial wafer to a desired level; and the ERO of the epitaxial wafer grown on the susceptor is brought to the above range by depositing a film layer of a predetermined thickness on the susceptor before epitaxial growth, thereby enabling the flatness of the epitaxial wafer to be brought to a desired level without affecting other quality parameters such as resistivity and thickness of the epitaxial wafer. BRIEF DESCRIPTION OF DRAWINGS

[0019] The features and advantages of embodiments of the present disclosure will become more apparent from the following description with reference to the accompanying drawings. The accompanying drawings are not drawn to scale, and some features can be exaggerated or minimised to show details that would otherwise be indistinguishible. In the drawings: Figure 1 The correlation of the ERO of an epitaxial wafer with the SFQR and the ESFQR is shown.

[0020] Figure 2 A schematic diagram for the definition of ERO.

[0021] Figure 3 A flowchart for a method for preparing an epitaxial wafer according to an embodiment of the present disclosure.

[0022] Figure 4 A structural schematic diagram of an exemplary epitaxial growth apparatus according to an embodiment of the present disclosure.

[0023] Figure 5 A structural schematic diagram of a system for preparing an epitaxial wafer according to an embodiment of the present disclosure.

[0024] In the drawings, the same or corresponding technical features or components are denoted by the same or corresponding reference numerals. DETAILED DESCRIPTION

[0025] The present disclosure is described in detail below with reference to the accompanying drawings and by way of exemplary embodiments. It is to be noted that the following detailed description of the present disclosure is merely for illustrative purposes and in no way limits the present disclosure.

[0026] As mentioned previously, in the related art, in order to obtain an epitaxial wafer of a desired level of flatness, the Recipe of the epitaxial growth process experienced by the wafer in forming the epitaxial wafer is adjusted. The Recipe includes epitaxial process operations and process parameters involved in the epitaxial growth process, etc. Exemplarily, the adjustment of the Recipe can involve adjustment of process parameters such as flow rate of reaction gas (such as SiHCl3 (i.e. TCS), H2), reaction temperature, etc.

[0027] However, adjustment of these parameters tends to affect the reaction conditions of the epitaxial growth reaction, such as the reaction rate, and so on, resulting in an impact on other quality parameters of the epitaxial wafer, such as the thickness and resistivity, while optimizing the flatness of the epitaxial wafer.

[0028] Therefore, it is desirable to be able to achieve the desired level of flatness of the epitaxial wafer without affecting other quality parameters of the epitaxial wafer, such as the thickness and resistivity.

[0029] To this end, first, the inventors noticed that, to achieve the desired level of flatness of the epitaxial wafer, it is necessary to achieve the desired level of flatness of both SFQR (Site Front surface referenced least sQuares / Range) and ESFQR (Edge Site Front surface referenced leastsQuares / Range) of the epitaxial wafer.

[0030] SFQR and ESFQR are two key indicators for measuring the flatness of a wafer. SFQR is used to describe the thickness variation within a specific area of the wafer surface, while ESFQR is used to describe the thickness variation within the edge region of the wafer. A comprehensive evaluation of the flatness of the wafer can be provided by referring to both parameters. Therefore, it can be determined that the flatness of the epitaxial wafer reaches the desired level by determining that both SFQR and ESFQR of the epitaxial wafer reach their respective desired levels.

[0031] Further, considering that abnormalities in SFQR are more likely to occur at the edge of the wafer, and that ESFQR is also a parameter for measuring the flatness of the edge of the wafer, the inventors tried to introduce a parameter ERO (Edge roll-off) that directly represents the thickness condition of the edge of the wafer, in an attempt to achieve the desired level of both SFQR and ESFQR by determining the range of a single parameter ERO.

[0032] Specifically, in order to determine the relationship between ERO and both SFQR and ESFQR, a certain number of epitaxial wafers obtained using the same process recipe were selected as test wafers, wherein the selected test wafers were epitaxial wafers with a diameter of 300 mm and an epitaxial layer thickness of 4 um. Data measurement and analysis were performed on the SFQR, ESFQR and ERO of the test wafers, and the data results are shown in Table 1. Figure 1

[0033] Here, the measurement methods of ERO, SFQR and ESFQR need to be explained. For reference, see Figure 2 ​A portion of the surface of the test wafer is shown by a curve, in which the abscissa represents the radius R of the test wafer, and the ordinate represents the thickness H of the test wafer. In the detection method of the commonly used ERO, the area 2 mm inward from the edge of the test wafer is excluded, and the point on the surface of the test wafer 148 mm (i.e. radius 148 mm) from the center thereof in the radial direction thereof is taken as the test point, and the ERO is determined by the difference between the actual value b of the thickness of the test wafer at the test point and the reference value a (ERO = b - a). The reference value a is the value of the point on the reference plane L corresponding to the test point, wherein the reference plane L is determined based on the thicknesses of the test wafer at radii 120 mm and 140 mm. Here, the surface of the wafer refers to the surface used for growing the epitaxial layer.

[0034] In determining the SFQR, the edge of the test wafer is excluded by 2 mm, and the surface of the test wafer after exclusion is divided into a plurality of sub-zone units each having a size of 26 mm x 8 mm, and for each sub-zone unit, a reference plane is calculated by the least square method, and the difference between the maximum value and the minimum value of the thickness calculated from the reference plane within each sub-zone unit is the SFQR value of the sub-zone unit.

[0035] In determining the ESFQR, the edge of the test wafer is excluded by 2 mm, and the edge after exclusion is divided into 72 sectors, each having a length of 15 mm, and for each sector, a reference plane is calculated by the least square method, and the difference between the maximum value and the minimum value of the thickness calculated from the reference plane within each sector is the ESFQR value of the sector.

[0036] Referring to the data results of Figure 1 , the inventors found that the ERO of the epitaxial wafer has a clear correlation with both the SFQR and the ESFQR: the ERO value range corresponding to the expected optimal numerical range of the SFQR overlaps with the ERO value range corresponding to the expected optimal numerical range of the ESFQR.

[0037] For example, as shown in Figure 1 , when the ERO is in the range of -10 nm to 5 nm, the SFQR is in the expected optimal numerical range, i.e. SFQR ≤ 20 nm, such as SFQR in the range of 10 nm to 20 nm; and when the ERO is in the range of -10 nm to 15 nm, the ESFQR is in the expected optimal numerical range, i.e. ESFQR ≤ 25 nm, such as ESFQR in the range of 12 nm to 25 nm. The two ERO value ranges overlap, and the overlapping range is -10 nm to 5 nm.

[0038] In this case, the SFQR and the ESFQR of the prepared epitaxial wafer can be simultaneously brought to the respective desired optimal value range by bringing the ERO of the prepared epitaxial wafer to the overlapping value range, so as to bring the flatness of the epitaxial wafer to the desired level. In this way, it is facilitated to quickly and effectively find the conditions for bringing the flatness of the epitaxial wafer to the desired level.

[0039] For example, as shown in Figure 1 , in the case where SFQR≤20 nm is taken as the desired level of SFQR and ESFQR≤25 nm is taken as the desired level of ESFQR, when the desired level of ERO is -10 nm to 5 nm, the SFQR and the ESFQR can be simultaneously brought to the respective desired levels.

[0040] Further, the inventors have also found that, for the ERO in the overlapping value range, the film layer of the predetermined thickness can be obtained by depositing on the susceptor before epitaxial growth, and this way basically does not affect the reaction process of actual epitaxial growth (i.e., does not affect or does not need to adjust the process recipe of the epitaxial growth process, for example, does not need to adjust the process parameters such as TCS flow rate, H2 flow rate, reaction temperature, etc.), so as not to affect other quality parameters such as thickness and resistivity of the obtained epitaxial wafer.

[0041] Therefore, according to the embodiments of the present disclosure, referring to Figure 3 , a method for preparing an epitaxial wafer is provided. The method comprises: Step S100: depositing a film layer of a predetermined thickness on a susceptor of an epitaxial growth device; and Step S200: epitaxially growing a wafer carried on the susceptor on which the film layer has been formed to obtain an epitaxial wafer, wherein The predetermined thickness can be determined according to the difference between the target ERO to be reached by the wafer after epitaxial growth and the initial ERO before the epitaxial growth.

[0042] Specifically, the target ERO is a preset target value or a preset target range of the final ERO of the prepared epitaxial wafer measured after the epitaxial growth of the wafer. The target ERO can be determined based on the overlapping value range of the ERO mentioned in the foregoing.

[0043] In order to facilitate understanding of the method, below, first, an exemplary epitaxial growth device 10 in Figure 4 will be described. It should be understood that the structure of the epitaxial growth device to which the method for preparing an epitaxial wafer according to the embodiments of the present disclosure can be applied is not limited thereto.

[0044] As shown in Figure 4As shown in the figure, the epitaxial growth apparatus 10 includes an upper quartz bell jar 111, a lower quartz bell jar 112, a susceptor 120, an inlet port 131, an outlet port 132, and a plurality of heating lamps 140.

[0045] The upper quartz bell jar 111 and the lower quartz bell jar 112 together define a growth chamber 150 for performing a chemical vapor deposition reaction therein to grow an epitaxial layer on a wafer.

[0046] The susceptor 120 is disposed within the growth chamber 150 and has a disc-shaped structure for carrying a wafer W, typically a polished wafer, to be subjected to epitaxial growth at a central region thereof.

[0047] The inlet port 131 is in communication with the growth chamber 150 at one side of the growth chamber 150 in a longitudinal direction thereof for delivering an epitaxial reaction gas, such as a silicon source gas like SiHCl3, H2, etc., to the growth chamber 150.

[0048] The outlet port 132 is in communication with the growth chamber 150 at another side of the growth chamber 150 in the longitudinal direction thereof for exhausting reaction exhaust gas from the growth chamber 150.

[0049] The heating lamps 140 are disposed outside the upper quartz bell jar 111 and the lower quartz bell jar 112 for heating the growth chamber 150 to provide a suitable temperature for the chemical vapor deposition reaction.

[0050] With reference to the above exemplary epitaxial growth apparatus 10, next, a method for preparing an epitaxial wafer according to an embodiment of the present disclosure will be explained more clearly.

[0051] Specifically, the step S100 is performed before the step S200, i.e., before actually depositing and growing an epitaxial layer on the wafer. For the step S100, a reaction gas (e.g., including a silicon source gas and a carrier gas) can be introduced into the growth chamber 150 of the epitaxial growth apparatus 10 via the inlet port 131, which will flow over the upper surface of the susceptor 120 under a high temperature environment of the growth chamber 150 and deposit a layer of thin film material of a predetermined thickness on the upper surface of the susceptor 120. For example, the thin film material can be a polysilicon material.

[0052] Since the film layer deposited on the susceptor 120 has a certain thickness, the thickness or height of the susceptor 120 can be adjusted by adjusting the thickness of the film layer, so that the flow path of the epitaxial reaction gas when flowing through the edge region of the wafer during the epitaxial growth process (i.e., during the step S200) is adjusted (raised), thereby affecting the thickness condition of the edge region of the prepared epitaxial wafer, i.e., changing the ERO of the epitaxial wafer.

[0053] That is, the thickness of the edge region of the epitaxial layer grown on the wafer can be adjusted by adjusting the thickness of the film layer deposited on the susceptor, so that the ERO of the final obtained epitaxial wafer reaches the target ERO, for example, in the above-mentioned overlapping numerical range. In other words, the film layer thickness to be adjusted can be determined according to the difference between the target ERO to be reached by the wafer after epitaxial growth and the initial ERO before the epitaxial growth. With the film layer thickness as the predetermined thickness, epitaxial growth is performed on the wafer carried on the susceptor on which the film layer with the predetermined thickness has been formed to obtain an epitaxial wafer, and the ERO of the epitaxial wafer can be the target ERO.

[0054] Moreover, the thickness of the deposited film layer is usually in the range of 2-3 μm, so that the change in the thickness of the film layer to the susceptor is in the order of microns, and thus it can affect the thickness of the edge of the wafer, especially in the range of several millimeters of the edge, but it does not affect the epitaxial growth of other positions or ranges of the wafer, i.e., the process recipe of the epitaxial growth process experienced by the wafer in forming the epitaxial wafer, such as the process parameters such as TCS flow rate, H2 flow rate, reaction temperature, etc., can not be adjusted. Thus, the flatness of the epitaxial wafer can be brought to the desired level without affecting other quality parameters of the epitaxial wafer, such as parameters related to resistivity and parameters related to epitaxial layer thickness, etc.

[0055] It is envisaged that step S100 can be implemented to deposit a film layer on both the central region of the susceptor 120 for carrying the wafer and the edge region outside the central region, but the film layer thicknesses of the two regions are different.

[0056] For obtaining a film layer with a predetermined thickness, in some embodiments, it can be achieved by controlling the deposition time of the film layer, or it can be achieved by controlling the deposition temperature of the film layer, or it can be achieved by controlling both the deposition time and the deposition temperature of the film layer. That is, the film layer with a predetermined thickness can be obtained by controlling at least one of the deposition time and the deposition temperature of the film layer.

[0057] For example, taking only the film layer with a predetermined thickness obtained by controlling the deposition time of the film layer as an example, the predetermined thickness of the film layer to be deposited can be determined according to the difference between the target ERO and the initial ERO, and the predetermined deposition time can be determined according to the predetermined thickness. Then, by depositing the film layer on the susceptor of the epitaxial growth device for the predetermined deposition time, the ERO of the obtained epitaxial wafer can be accurately controlled to reach the target ERO, so that the epitaxial wafer can accordingly obtain the desired levels of SFQR and ESFQR, so that the flatness of the epitaxial wafer can be brought to the desired level without affecting other quality parameters of the epitaxial wafer such as resistivity, thickness, etc.

[0058] It is conceived that it is also possible to try to establish a relationship between the difference between the target ERO and the initial ERO and the predetermined deposition time directly without resorting to the predetermined thickness as an intermediate object. That is, the predetermined deposition time is determined directly according to the difference between the target ERO to be reached by the wafer after the epitaxial growth and the initial ERO before the epitaxial growth. In this way, the film layer is deposited on the susceptor of the epitaxial growth device directly with the predetermined deposition time, and the wafer carried on the susceptor on which the film layer has been formed is subjected to epitaxial growth, so that the epitaxial wafer with the ERO being the target ERO can be obtained.

[0059] It is further discovered through collecting a series of experimental data of the initial ERO and the final ERO of the wafer before and after the epitaxial growth under the condition that the film layer is deposited on the susceptor with different predetermined deposition times and processing and analyzing the collected experimental data that, under the condition that other deposition conditions are the same, the corresponding relationship between the predetermined deposition time of the film layer and the ERO change amount (ΔERO for short, i.e. the difference between the final ERO of the epitaxial wafer obtained after the epitaxial growth of the wafer and the initial ERO of the wafer before the epitaxial growth) of the wafer before and after the epitaxial growth caused by the deposition of the film layer with the predetermined deposition time is determined.

[0060] The corresponding relationship between the four different predetermined deposition times (Experiments 1 to 4) taken in the film layer deposition process and the ΔERO of the wafer caused by taking different predetermined times is exemplarily listed in Table 1.

[0061]

[0062] Table 1 Based on this, it can be determined that the predetermined deposition time can be determined according to the difference between the target ERO and the initial ERO.

[0063] Exemplarily, the determination of the predetermined deposition time can include the following steps: the target ERO is preset; the initial ERO of any wafer to be subjected to epitaxial growth is measured; the difference between the target ERO and the initial ERO is calculated; and the predetermined deposition time corresponding to the difference is determined as the actually adopted predetermined deposition time according to the corresponding relationship between the calculated difference and the predetermined deposition time (for example, according to a comparison table similar to Table 1), and the epitaxial wafer with the ERO being the target ERO can be obtained by depositing the film layer with the predetermined deposition time and subjecting the wafer carried on the susceptor on which the film layer has been formed to epitaxial growth.

[0064] For example, the target ERO can be preset as 3 nm. If the initial ERO of a wafer to be subjected to epitaxial growth is measured to be -67 nm, the calculated difference between the target ERO and the initial ERO is 70 nm. Then, referring to Table 1, it can be determined that the required predetermined time is 10 s.

[0065] It is also conceivable that a relationship can be established directly between the difference between the target ERO and the initial ERO and the predetermined deposition temperature without the aid of the predetermined thickness as an intermediate object.

[0066] Similar to the above-mentioned experiment of depositing the film layer with different predetermined deposition times, through data collection and analysis, the corresponding relationship between the predetermined deposition temperature of the film layer and the AERO under the same other deposition conditions is also determined.

[0067] The corresponding relationship between the four different predetermined deposition temperatures (experiments 5 to 8) taken during the film layer deposition process and the AERO of the wafer caused by taking different predetermined temperatures is exemplarily listed in Table 2.

[0068]

[0069] Table 2 Based on this, it can be determined that the predetermined deposition temperature can be determined according to the difference between the target ERO and the initial ERO.

[0070] Moreover, similarly, it is also conceivable that a relationship can be established directly between the difference between the target ERO and the initial ERO and both the predetermined deposition time and the predetermined deposition temperature without the aid of the predetermined thickness as an intermediate object.

[0071] Since the corresponding relationship between the predetermined deposition time and the AERO and the corresponding relationship between the predetermined deposition temperature and the AERO are both determined, the corresponding relationship between both the predetermined deposition time and the predetermined deposition temperature and the AERO can also be determined.

[0072] In some embodiments, the target ERO can also be a numerical range. For example, the numerical range can be -10 nm to 5 nm. However, the target ERO is not limited to this numerical range.

[0073] For example, the target ERO can be the numerical range of -10 nm to -5 nm. As shown in Table 1, when the ERO of the epitaxial wafer falls within this numerical range, the SFQR of the epitaxial wafer can fall between 12 nm and 20 nm and the ESFQR can fall between 18 nm and 25 nm at the same time. Figure 1

[0074] It can be understood that when the target ERO is a numerical range, the difference between the calculated target ERO and the initial ERO is also a numerical range, and thus the corresponding range of at least one of the predetermined deposition time and the predetermined deposition temperature can be determined according to the numerical range of the difference. Based on this, a numerical value such as the deposition time, the deposition temperature or both can be selected in the corresponding range for film layer deposition.

[0075] ​For the sake of convenience, only the predetermined deposition time is taken as an example to be described below instead of the at least one described above.

[0076] In some embodiments, the same predetermined deposition time can be used for wafers with initial EROs in the same interval. Here, the interval is one of a plurality of intervals into which the initial ERO is classified according to the target ERO being a numerical range.

[0077] Specifically, in the case where the target ERO is a numerical range, the initial ERO can be classified into a plurality of intervals according to the numerical range, so that wafers to be subjected to epitaxial growth can be classified into a plurality of categories according to the plurality of intervals of the initial ERO, wherein wafers with initial EROs in the same interval are classified into one category. For wafers in the same category, the same predetermined deposition time is used when depositing the film layer, so that the ERO reached by the wafers in the same category after epitaxial growth is the target ERO.

[0078] In the case where the initial ERO of the wafer is classified by intervals, when the initial ERO of the wafer to be subjected to epitaxial growth is known, the predetermined deposition time required for the film layer deposition can be determined by judging which interval the initial ERO falls into. Compared with determining a specific predetermined deposition time for each wafer individually, the preparation of the entire epitaxial wafer is simplified, and the production efficiency is improved.

[0079] Illustratively, the initial ERO can be classified into intervals according to the difference between the numerical range and different ERO change amounts (i.e., ΔERO). Here, the different ERO change amounts are the difference between the ERO of the wafer after epitaxial growth and the ERO before epitaxial growth caused by different predetermined deposition times, as shown in Table 1 and Table 3.

[0080] For example, based on Table 1, in combination with Table 3 below, taking the numerical range of the target ERO as -10 nm to 5 nm as an example, the initial ERO can be classified into four intervals according to the difference between the numerical range and four different ΔERO, each interval corresponding to a predetermined deposition time.

[0081] Specifically, as shown in Table 3, the initial ERO can be classified into the following intervals: -80 nm to -65 nm, -63 nm to -48 nm, -47 nm to -32 nm, and -31 nm to -16 nm. The predetermined deposition times corresponding to the four intervals are 10 s, 20 s, 30 s, and 60 s, respectively.

[0082] For example, for wafers with initial EROs in the range of -31 nm to -16 nm, a predetermined deposition time of 60 s is used to deposit a film layer on the susceptor, thereby enabling the ERO reached by the wafer after epitaxial growth to be in the range of -10 nm to 5 nm.

[0083]

[0084] Table 3 However, the way of interval classification of the initial ERO is not limited to this, for example, interval classification can also be performed by means of other data processing methods after a certain amount of initial ERO and final ERO data is collected.

[0085] In some embodiments, depositing the film layer on the susceptor of the epitaxial growth apparatus can be performed after the epitaxial growth apparatus is cleaned.

[0086] After each epitaxial growth process, in addition to growing an epitaxial layer on the wafer to be grown epitaxially, a thin film can also be deposited on the susceptor of the reaction chamber, covering the surface thereof. Here, cleaning the epitaxial growth apparatus means that a cleaning process recipe is used on the growth chamber of the epitaxial growth apparatus to remove the deposits formed on the surface of the susceptor in the previous epitaxial growth process. For example, removal can be achieved by introducing etching gas such as hydrogen chloride into the growth chamber.

[0087] With the cleaning of the susceptor of the epitaxial growth apparatus, the film layer deposition process in the embodiments of the present disclosure can be more accurately controlled, the interference of the previous susceptor deposits is excluded, so that the film layer of the predetermined thickness and the desired target ERO can be more accurately obtained.

[0088] According to another aspect of the present disclosure, referring to Figure 5 A system 20 for preparing an epitaxial wafer is also provided. The system 20 for preparing an epitaxial wafer comprises: a growth unit 210 configured to deposit a film layer of a predetermined thickness on a susceptor of an epitaxial growth apparatus, and to perform epitaxial growth on a wafer carried on the susceptor on which the film layer has been formed to obtain an epitaxial wafer; and a processing unit 220 configured to determine the predetermined thickness according to a difference between a target ERO to be reached by the wafer after epitaxial growth and an initial ERO before epitaxial growth.

[0089] In some embodiments, the growth unit 210 obtains the film layer of the predetermined thickness by controlling at least one of a deposition time and a deposition temperature of the film layer.

[0090] In some embodiments, the processing unit 220 can be configured to, for a wafer whose initial ERO is in a same interval, cause the growth unit 210 to perform film layer deposition using at least one of a deposition time and a deposition temperature of the film layer, wherein the interval is one of a plurality of intervals into which the initial ERO is classified according to the target ERO which is a numerical range.

[0091] According to yet another aspect of the present disclosure, a system for preparing an epitaxial wafer is also provided. The system comprises: a growth unit configured to deposit a film layer on a susceptor of an epitaxial growth apparatus with at least one of a predetermined deposition time and a predetermined deposition temperature, and to perform epitaxial growth on a wafer carried on the susceptor on which the film layer has been formed to obtain an epitaxial wafer; and a processing unit configured to determine the at least one according to a difference between a target ERO to be reached by the wafer after the epitaxial growth and an initial ERO before the epitaxial growth.

[0092] According to still another aspect of the present disclosure, an epitaxial wafer is also provided, which is prepared according to the method for preparing an epitaxial wafer of embodiments of the present disclosure, and has an SFQR≤20nm and an ESFQR≤25nm.

[0093] In some embodiments, the SFQR is in a range of 10nm to 20nm, and the ESFQR is in a range of 12nm to 25nm.

[0094] In some embodiments, the ERO of the epitaxial wafer is in a range of -10nm to 5nm.

[0095] Although the present disclosure has been described with reference to the example embodiments, it is to be understood that the present disclosure is not limited to the particular embodiments described and / or illustrated herein. Various modifications can be made to the example embodiments by those skilled in the art without departing from the scope of the present disclosure as defined by the claims.

[0096] Features mentioned and / or shown in the above description of the example embodiments of the present disclosure can be incorporated in one or more other embodiments in the same or analogous manner, combined with other features of the other embodiments or replace corresponding features of the other embodiments. The technical solutions obtained by combining or replacing should also be regarded as included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be subject to the scope of protection of the claims.

Claims

1. A method for preparing an epitaxial wafer, characterized by, The method comprises: depositing a film layer of a predetermined thickness on a susceptor of an epitaxial growth device; and performing epitaxial growth on a wafer carried on the susceptor on which the film layer has been formed to obtain an epitaxial wafer, wherein the predetermined thickness is determined according to a difference between a target ERO to be reached by the wafer after the epitaxial growth and an initial ERO before the epitaxial growth.

2. The method for producing an epitaxial wafer according to claim 1, wherein The film layer of the predetermined thickness is obtained by controlling at least one of a deposition time and a deposition temperature of the film layer.

3. The method for producing an epitaxial wafer according to claim 2, wherein The at least one is determined according to an interval in which the initial ERO is located, wherein the interval is one of a plurality of intervals obtained by classifying the initial ERO according to the target ERO in a case where the target ERO is a numerical range.

4. The method for producing an epitaxial wafer according to claim 3, wherein The numerical range is -10 nm to 5 nm.

5. The method for preparing an epitaxial wafer according to claim 1, wherein The depositing of the film layer of the predetermined thickness on the susceptor of the epitaxial growth device is performed after the epitaxial growth device is cleaned.

6. The method for preparing an epitaxial wafer according to claim 1, wherein The predetermined thickness is in a range of 2 μm to 3 μm.

7. A method for preparing an epitaxial wafer, characterized by, The method comprises: depositing a film layer on a susceptor of an epitaxial growth device with at least one of a predetermined deposition time and a predetermined deposition temperature; and performing epitaxial growth on a wafer carried on the susceptor on which the film layer has been formed to obtain an epitaxial wafer, wherein the at least one is determined according to a difference between a target ERO to be reached by the wafer after the epitaxial growth and an initial ERO before the epitaxial growth.

8. A system for preparing an epitaxial wafer, characterized by, The method comprises: a growth unit configured to deposit a film layer of a predetermined thickness on a susceptor of an epitaxial growth device, and to perform epitaxial growth on a wafer carried on the susceptor on which the film layer has been formed to obtain an epitaxial wafer; and a processing unit configured to determine the predetermined thickness according to a difference between a target ERO to be reached by the wafer after the epitaxial growth and an initial ERO before the epitaxial growth.

9. A system for preparing an epitaxial wafer, characterized by, The method comprises: a growth unit configured to deposit a film layer on a susceptor of an epitaxial growth device with at least one of a predetermined deposition time and a predetermined deposition temperature, and to perform epitaxial growth on a wafer carried on the susceptor on which the film layer has been formed to obtain an epitaxial wafer; and a processing unit configured to determine the at least one according to a difference between a target ERO to be reached by the wafer after the epitaxial growth and an initial ERO before the epitaxial growth.

10. An epitaxial wafer, characterized by, The epitaxial wafer is prepared according to the method for preparing an epitaxial wafer of any one of claims 1 to 7, and has an SFQR ≤ 20 nm and an ESFQR ≤ 25 nm.

11. The epitaxial wafer of claim 10, wherein, The epitaxial wafer has an ERO in a range of -10 nm to 5 nm.

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