Method for growing epitaxial layer of wafer

Abstract

The embodiment provides a method for growing an epitaxial layer on a wafer, comprising the steps of: cleaning an epitaxial layer growth apparatus; growing an epitaxial layer on a wafer within the epitaxial layer growth apparatus; measuring the in-plane temperature distribution of the epitaxial layer grown on the wafer; evaluating whether the quality of the epitaxial layer grown on the wafer satisfies a preset standard; and changing the process temperature distribution of the epitaxial layer growth apparatus if the quality of the epitaxial layer grown on the wafer deviates from the preset standard.

Description

Technology Field

[0001] The present invention relates to a method for growing an epitaxial layer on a wafer, and more specifically, to a method for growing an epitaxial layer uniformly on a wafer by controlling the temperature distribution within an epitaxial layer growth apparatus. Background Technology

[0002] Silicon wafers, which are used as materials for producing electronic components such as semiconductors or solar cells, are manufactured by growing a silicon single-crystal ingot using the Czochralski (CZ) method or a series of processes. Then, semiconductors are manufactured through processes such as implanting specific ions into the wafer and forming circuit patterns.

[0003] In particular, an epitaxial silicon wafer (hereinafter referred to as "epifaxial wafer") is formed by growing an epitaxial thin film of a silicon single crystal on the surface of a polished wafer.

[0004] These epitaxial wafers are formed by vapor-growing a high-resistivity silicon epitaxial layer on a low-resistivity silicon wafer. They have gettering ability, low latch-up characteristics, and resistance to slip at high temperatures, and are currently widely used as wafers for LSI devices as well as MOS devices.

[0005] Epitaxial wafers are manufactured through a process in which a polished wafer is placed on a susceptor inside a chamber, heated to a high temperature, a source gas is supplied to the chamber, and the supplied source gas reacts with the polished wafer to grow an epitaxial thin film on the wafer surface.

[0006] At this time, when controlling the temperature in the wafer epitaxial layer growth device, the temperature is measured from low to high using a thermocouple in a hydrogen (H2) atmosphere. Then, the temperature calibration curve derived by the above-described method is performed once during the initial setup, and after a certain period of time, the epitaxial layer is grown on the wafer, and each epitaxial layer growth process can be referred to as a run.

[0007] In addition, a cleaning process is performed inside the epitaxial layer growth device after each run, so that the temperature distribution within the wafer plane is uniform in subsequent runs in which the epitaxial layer is grown, thereby allowing the epitaxial layer of the same quality to be grown.

[0008] The cleaning described above is carried out in a high-temperature atmosphere by supplying a cleaning gas, such as HCl, to remove deposits that accumulate inside the chamber during the run.

[0009] However, there is a problem with reduced productivity when cleaning is performed between each run, and if multiple runs are performed between cleaning to solve the problem of reduced productivity, a difference in the quality of the epitaxial layer may occur due to an imbalance in the temperature distribution within the wafer between the run immediately after cleaning and the subsequent run. The problem to be solved

[0010] The present invention aims to provide a method for growing an epitaxial layer on a wafer in which the quality of the epitaxial layer grown on the wafer is uniform by making the temperature distribution within the wafer plane uniform in each run when a plurality of runs are performed in an epitaxial layer growth apparatus. means of solving the problem

[0011] The embodiment provides a method for growing an epitaxial layer on a wafer, comprising the steps of: cleaning an epitaxial layer growth apparatus; growing an epitaxial layer on a wafer within the epitaxial layer growth apparatus; measuring the in-plane temperature distribution of the epitaxial layer grown on the wafer; evaluating whether the quality of the epitaxial layer grown on the wafer satisfies a preset standard; and changing the process temperature distribution of the epitaxial layer growth apparatus if the quality of the epitaxial layer grown on the wafer deviates from the preset standard.

[0012] A method for growing an epitaxial layer on a wafer may further include the step of evaluating whether the number of growth cycles of the epitaxial layer is less than a preset standard after growing the epitaxial layer on the wafer in an epitaxial layer growth device.

[0013] If the number of times the epitaxial layer is grown is less than a preset standard, the step of growing the epitaxial layer on the wafer within the epitaxial layer growth device can be repeated.

[0014] If the number of growth cycles of the epitaxial layer exceeds a preset standard, a step of measuring the in-plane temperature distribution of the epitaxial layer grown on the wafer can be performed.

[0015] The step of changing the process temperature distribution of the epitaxial layer growth device can change the output of the first lamps above the susceptor and the second lamps below the susceptor within the epitaxial layer growth device.

[0016] The first lamps at the upper part of the susceptor in the epitaxial layer growth device include first-1 lamps in the central region and first-2 lamps in the edge region, and the second lamps at the lower part of the susceptor in the epitaxial layer growth device may include second-1 lamps in the central region and second-2 lamps in the edge region.

[0017] The step of changing the process temperature distribution of the epitaxial layer growth apparatus may include adding a first variable to the existing output of the first-1 lamps, adding a second variable to the existing output of the first-2 lamps, adding a third variable to the existing output of the second-1 lamps, and adding a fourth variable to the existing output of the second-2 lamps. Effects of the invention

[0018] In the method for growing an epitaxial layer of a wafer according to the present invention, a cleaning process between each run is omitted, and a variable for the output of each lamp is introduced so that an epitaxial layer of the same quality can be grown for each run. Brief explanation of the drawing

[0019] FIG. 1 is a diagram showing a method for growing an epitaxial layer of a wafer according to one embodiment of the present invention. FIG. 2 is a diagram showing an epitaxial layer growth apparatus for a wafer according to an embodiment. Figure 3a is a diagram showing the temperature distribution within the surface of a wafer in a conventional method for growing an epitaxial layer of a wafer. FIG. 3b is a diagram showing the temperature distribution within the surface of a wafer in a method for growing an epitaxial layer of a wafer according to an embodiment. FIG. 4 shows the temperature distribution in each region of the wafer according to the beta value, i.e., the value at which the output of the first and second lamps is changed in the above-described embodiment. Figure 5 shows SFQR data for each run in Comparative Example 1 and Example 1. Figure 6 shows ESFQR data for each run in Comparative Example 1 and Example 1. Specific details for implementing the invention

[0020] Hereinafter, to specifically explain the present invention, examples of embodiments will be described, and to facilitate understanding of the invention, the invention will be described in detail with reference to the accompanying drawings.

[0021] However, embodiments according to the present invention may be modified in various other forms, and the scope of the present invention should not be interpreted as being limited to the embodiments described below. The embodiments of the present invention are provided to more fully explain the present invention to those with average knowledge in the art.

[0022] Additionally, relational terms such as "first" and "second," "upper" and "lower," etc., used below, may be used solely to distinguish one entity or element from another, without necessarily requiring or implying any physical or logical relationship or order between such entities or elements.

[0023] FIG. 1 is a diagram showing a method for growing an epitaxial layer of a wafer according to one embodiment of the present invention.

[0024] The method for growing an epitaxial layer of a wafer according to the present embodiment comprises the steps of: cleaning an epitaxial layer growth apparatus (S110); growing an epitaxial layer on a wafer within the epitaxial layer growth apparatus (S120); evaluating whether the number of growth cycles of the epitaxial layer is less than a preset standard (S130); measuring the in-plane temperature distribution of the epitaxial layer grown on the wafer (S140); evaluating whether the quality of the epitaxial layer grown on the wafer satisfies a preset standard (S150); and changing the process temperature distribution of the epitaxial layer growth apparatus (S160).

[0025] FIG. 2 is a drawing showing an epitaxial layer growth apparatus for a wafer according to an embodiment. As shown in FIG. 2, the apparatus used in the method for growing an epitaxial layer for a wafer according to the present embodiment allows a wafer to be placed on a susceptor (200) placed inside a process chamber to grow an epitaxial layer, and first lamps (500) and second lamps (600) can be placed at the top and bottom of the process chamber, respectively.

[0026] Additionally, although not shown, thermometers may be provided at the top and bottom of the process chamber, respectively, but are not limited thereto.

[0027] The susceptor (200) may include, but is not limited to, a main shaft (210) acting as a central axis, three support shafts (220a, 220b, 220c) extending from the main shaft (210) and extending toward the edge of the wafer, and first to third lift pins (240a, 240b, 240c) disposed at the ends of the three support shafts (220a, 220b, 220c) to support the wafer.

[0028] The process chamber may include an upper dome (100) and a lower dome (150) respectively provided at the upper and lower portions of the susceptor (200) and the first to third lift pins (240a, 240b, 240c), and the regions inside the upper dome (100) and the lower dome (150) may form a growth space for the epitaxial layer. Additionally, the process chamber may have a gas inlet (in) and a gas outlet (out) formed to form a film, such as an epitaxial layer, on the surface of a wafer.

[0029] Although not shown, the upper dome (100) may be equipped with a wafer vision area, through which the warping of the wafer during the epitaxial layer deposition process can be observed.

[0030] A carrier gas, such as hydrogen, and / or a source gas (or reaction gas), such as a silane like SiHCl3 or SiH2Cl2, which are necessary to grow an epitaxial layer on a wafer, may be introduced through a gas inlet (in) to form an epitaxial layer on the wafer, and after the formation of the epitaxial layer, the remaining gas may be discharged through a gas outlet (out). As illustrated, the gas inlet (in) and the gas outlet (out) may be formed facing each other, but are not limited thereto.

[0031] And, a susceptor (200) is provided between the gas inlet (in) and the gas outlet (out), so that the gas inlet (in) and the gas outlet (out) are located at a height almost equal to the upper surface of the susceptor (200), so that the raw gas introduced through the gas inlet (in) can flow along the surface of the wafer.

[0032] In order to control the temperature inside the process chamber, light is emitted from the first lamp (500) and the second lamp (600), respectively, placed at the top and bottom of the susceptor (200), to the upper and lower regions of the susceptor (200), and the radiant heat emitted from the first and second lamps (500, 600) can be transferred toward the wafer. At this time, the first lamp (500) may be called the top lamp and the second lamp (600) may be called the bottom lamp.

[0033] At this time, among the first lamps (500) provided in the upper region of the susceptor (200), the one provided in the central region can be distinguished as the first-1 lamp (500a) and the one provided in the edge region as the first-2 lamp (500b), and among the second lamps (600) provided in the lower region, the one provided in the central region can be distinguished as the second-1 lamp (600a) and the one provided in the edge region as the second-2 lamp (600b).

[0034] Hereinafter, with reference to FIGS. 1 and FIGS. 2, a method for growing an epitaxial layer of a wafer according to an embodiment of the present invention will be described in detail.

[0035] First, the inside of the epitaxial layer growth device is cleaned. Since silicon layers (Si layers) or other foreign substances may accumulate inside the epitaxial layer growth device during the epitaxial layer growth process, silicon layers or other foreign substances can be removed through the cleaning process.

[0036] And, an epitaxial layer can be grown on a wafer within an epitaxial layer growth device. Specifically, an epitaxial layer can be grown as a thin film on a wafer on a susceptor (200) placed inside a process chamber.

[0037] Then, it is evaluated whether the number of epitaxial layer growth cycles is less than a preset standard. That is, if the number of epitaxial layer growth cycles is preset to, for example, 5 times, and the number of epitaxial layer growth cycles is less than 5 times, the step of growing an epitaxial layer on a wafer within the epitaxial layer growth device can be repeated.

[0038] And, when the number of epitaxial layer growth cycles exceeds a preset standard, that is, when the number of epitaxial layer growth cycles reaches 5, the temperature distribution within the plane of the epitaxial layer grown on the wafer can be measured. That is, when the growth of the epitaxial layer is completed, the temperature distribution within the plane of the wafer can be measured, and the temperature distribution in the central region and edge region of the front and back surfaces of the wafer can be measured.

[0039] In addition, it is possible to evaluate whether the quality of the epitaxial layer grown on the wafer satisfies preset criteria. The quality of the epitaxial layer may be, for example, the uniformity of the thickness of the thin film or the presence or absence of defects.

[0040] If the quality of the epitaxial layer grown on the wafer satisfies a preset standard, the process of growing the epitaxial layer on the wafer can be terminated.

[0041] In addition, if the quality of the epitaxial layer grown on the wafer does not meet the preset criteria, the process temperature distribution of the epitaxial layer growth device can be changed. At this time, changing the process temperature distribution of the epitaxial layer growth device can change the output of the first lamps above the susceptor and the second lamps below the susceptor within the epitaxial layer growth device.

[0042] More specifically, a first variable can be added to the existing output of the 1-1 lamps, a second variable can be added to the existing output of the 1-2 lamps, a third variable can be added to the existing output of the 2-1 lamps, and a fourth variable can be added to the existing output of the 2-2 lamps.

[0043] That is, before changing the output of the first and second lamps, if the total output of the first and second lamps is 100 and the total output of the second lamp is A%, then the total output of the first lamp can be (100-A)%. Also, when the total output of the first lamp is 100, if the total output of the first-1 lamps is B%, then the total output of the first-2 lamps can be (100-B)%. Also, when the total output of the second lamps is 100, if the total output of the second-1 lamps is C%, then the total output of the second-2 lamps can be (100-C)%.

[0044] And, the modified outputs of the first and second ramps may be as follows. For example, if the first to fourth variables are denoted as alpha (α), beta (β), gamma (γ), and delta (δ), respectively, the total output of the first-1 ramps is (B+alpha)%, the total output of the first-2 ramps is (100-B+beta)%, the total output of the second-1 ramps is (C+gamma)%, and the total output of the second-2 ramps is (100-C+delta)%.

[0045] By changing the output of each lamp using the method described above, the temperature distribution of each region of the wafer in subsequent runs can be controlled, thereby changing the temperature distribution within the wafer surface and improving the quality of the growing epitaxial layer.

[0046] FIG. 3a is a diagram showing the temperature distribution within the surface of a wafer in a conventional method for growing an epitaxial layer of a wafer, and FIG. 3b is a diagram showing the temperature distribution within the surface of a wafer in a method for growing an epitaxial layer of a wafer according to an embodiment.

[0047] The vertical axis represents temperature, and the horizontal axis represents distance from the center of the wafer. In Comparative Example 1 of FIG. 3a, the temperature distribution in each region of the wafer differs in each run, which may be attributed to the cleaning process being performed between each run. In Example 1 of FIG. 3b, as described above, after performing a cleaning treatment before the first run, the output of the lamps in each run is adjusted so that the temperature distribution in each region of the wafer can be controlled to be nearly identical.

[0048] Table 1 below shows the temperature change for each run in the central, intermediate, and edge regions of the wafer in Figures 3a and 3b. The central region refers to the center of the wafer, the intermediate region refers to an area spaced approximately 75 millimeters from the central region, and the edge region refers to an edge area spaced approximately 148 millimeters from the central region. The temperatures of the wafer in the central, intermediate, and edge regions are listed, and the delta value represents the temperature difference between the central region and the edge region.

[0049] Number of runs Central area (°C) Intermediate range (°C) Edge region (°C) Delta value (°C) Example 1 1 1130 1127.714 1136.618 -6.618 2 1130 1127.481 1136.75 -6.750 3 1130 1127.948 1136.485 -6.485 Comparative Example 1 1 1130 1128.449 1138.531 -8.531 2 1130 1127.675 1136.625 -6.625 3 1130 1127.918 1136.435 -6.435

[0050] FIG. 4 shows the temperature distribution in each region of the wafer according to the beta value, that is, the value at which the output of the first and second lamps is changed in Example 1 described above. That is, it shows the temperature distribution in each region of the wafer before the output of the first and second lamps is changed and when the output is changed by the beta value.

[0051] Table 2 shows the temperature change for each run in the central, intermediate, and edge regions of the wafer when the above beta value changes from +20% to -20%. The central region refers to the center of the wafer, the intermediate region refers to the region spaced about 75 millimeters from the center region, and the edge region refers to the edge region spaced about 148 millimeters from the center region. It can be seen that the temperature of the edge region of the wafer changes mainly as the beta value increases or decreases, that is, as the output values ​​of the first and second lamps provided in the edge region of the wafer are increased or decreased. At this time, it can be seen that the degree of temperature change in the edge region of the wafer is smaller than the delta value in Table 1 above.

[0052] Beta value (%) Central area (°C) Intermediate range (°C) Edge region (°C) +20 0.050 0.867 4.139 +10 0.123 0.840 3.288 +5 0.153 0.687 1.895 -5 0.034 0.421 -0.587 -10 0.021 0.499 -1.192 -20 0.028 0.429 -2.853

[0053] Figure 5 shows SFQR data for each run in Comparative Example 1 and Example 1, and Figure 6 shows ESFQR data for each run in Comparative Example 1 and Example 1.

[0054] SFQR (Site Flatness Front Least Square Range) indicates the degree of flatness across the entire front surface of the wafer, and ESFQR (Edge Site Flatness Front Least Square Range) indicates the degree of flatness, particularly at the edge area, across the front surface of the wafer.

[0055] As can be seen in FIG. 5, the deviation of the SFQR value in each run of Comparative Example 1 (Not Applied) is large compared to Example 1 (Appleid), and in FIG. 6, the deviation of the ESFQR value in each run of Comparative Example 1 (Not Applied) is large compared to Example 1 (Appleid).

[0056] That is, in the case of the comparative example, due to the cleaning process between each run, the flatness of the front surface of the wafer is reduced, and consequently, the quality of the growing epitaxial layer may also be reduced.

[0057] After the cleaning process of a conventional chamber, the temperature inside the chamber increases and does not cool down completely even after cooling, resulting in latent heat. This latent heat can create a difference between the heat distribution within the wafer surface immediately after the cleaning process and the heat distribution within the wafer surface during multiple runs.

[0058] In the method for growing an epitaxial layer of a wafer according to the present invention, a cleaning process between each run is omitted, and a variable for the output of each lamp is introduced so that an epitaxial layer of the same quality can be grown for each run.

[0059] Although embodiments of the present invention have been described in more detail with reference to the attached drawings, the present invention is not necessarily limited to these embodiments and can be modified in various ways within the scope of the technical spirit of the present invention. Accordingly, the embodiments disclosed in the present invention are intended to explain, not to limit, the technical spirit of the present invention, and the scope of the technical spirit of the present invention is not limited by these embodiments.

[0060] Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. The scope of protection of the present invention shall be interpreted by the claims below, and all technical ideas within the equivalent scope shall be interpreted as being included within the scope of rights of the present invention. Explanation of the symbols

[0061] 100: Upper dome 150: Lower dome 200: Susceptor 210: Main Shaft 220a~220c: Support shaft 240a~240c: Lift pin 500: 1st lamp 500a: 1-1st lamp 500b: 1st-2nd Ramp 600: 2nd Ramp 600a: Ramp 2-1 600b: Ramp 2-2

Claims

Claim 1 A step of cleaning an epitaxial layer growth apparatus; a step of growing an epitaxial layer on a wafer within the epitaxial layer growth apparatus; a step of measuring the in-plane temperature distribution of the epitaxial layer grown on the wafer; a step of evaluating whether the quality of the epitaxial layer grown on the wafer satisfies a preset standard; A method for growing an epitaxial layer of a wafer, wherein if the quality of the epitaxial layer grown on the wafer deviates from a preset standard, the method comprises the step of changing the process temperature distribution of the epitaxial layer growth apparatus, wherein the step of changing the process temperature distribution of the epitaxial layer growth apparatus comprises changing the outputs of first lamps above the susceptor and second lamps below the susceptor within the epitaxial layer growth apparatus, wherein the first lamps include first-1 lamps in a central region and first-2 lamps in an edge region, and the second lamps include second-1 lamps in a central region and second-2 lamps in an edge region, and adding a first variable to the existing output of the first-1 lamps, adding a second variable to the existing output of the first-2 lamps, adding a third variable to the existing output of the second-1 lamps, and adding a fourth variable to the existing output of the second-2 lamps to grow an epitaxial layer of the same quality for each growth process. Claim 2 A method for growing an epitaxial layer of a wafer according to claim 1, further comprising the step of evaluating whether the number of growth cycles of the epitaxial layer is less than a preset standard after growing an epitaxial layer on a wafer in the epitaxial layer growth apparatus. Claim 3 A method for growing an epitaxial layer of a wafer according to claim 2, wherein if the number of growth cycles of the epitaxial layer is less than a preset standard, the step of growing an epitaxial layer on the wafer within the epitaxial layer growth apparatus is repeated. Claim 4 A method for growing an epitaxial layer of a wafer according to claim 2, wherein if the number of growth cycles of the epitaxial layer is greater than or equal to a preset standard, the step of measuring the in-plane temperature distribution of the epitaxial layer grown on the wafer. Claim 5 delete Claim 6 delete Claim 7 delete

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