KR20230056289A - Method for growing epitaxial layer of wafer - Google Patents

Abstract

An embodiment provides a method for growing an epitaxial layer of a wafer, including the steps of: cleaning an epitaxial layer growth device; growing an epitaxial layer on a wafer in the epitaxial layer growth device; 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 device when the quality of the epitaxial layer grown on the wafer deviates from the preset standard.

Description

Method for growing an epitaxial layer of a wafer {METHOD FOR GROWING EPITAXIAL LAYER OF WAFER}

The present invention relates to a method for growing an epitaxial layer on a wafer, and more particularly, to a method for uniformly growing an epitaxial layer on a wafer by controlling a temperature distribution in an epitaxial layer growing apparatus.

A silicon wafer used as a material for producing electronic components such as semiconductors or solar cells is manufactured through a series of processes after growing a silicon single crystal ingot by a czochralski (CZ) method or the like. Then, a semiconductor is manufactured through processes such as implanting predetermined ions into the wafer and forming a circuit pattern.

In particular, an epitaxial silicon wafer grown on the surface of a polished wafer is referred to as an epitaxial silicon wafer (hereinafter referred to as an 'epitaxial wafer').

These epitaxial wafers are obtained by vapor-growing a high-resistivity silicon epitaxial layer on a low-resistivity silicon wafer, and have gettering capability, low latch-up characteristics, and resistance to slip at high temperatures. , has recently been widely used as a wafer for LSI devices as well as MOS devices.

In the epitaxial wafer, a polishing wafer is placed on a susceptor in a chamber, heated to a high temperature, source gas is supplied to the chamber, and an epitaxial thin film is grown on the wafer surface by reacting the supplied source gas with the polishing wafer. Manufactured through a process

At this time, when controlling the temperature in the apparatus for growing the epitaxial layer of the wafer, the temperature is measured from low temperature to high temperature using a thermocouple in a hydrogen (H ₂ ) atmosphere. In addition, the temperature calibration curve derived by the above-described method is performed once during initial setup, and then after a certain period of time to grow the epitaxial layer on the wafer. Each epitaxial layer The growth process of can be called a run.

In addition, after each run, a cleaning process inside the epitaxial layer growth apparatus is performed, so that the in-plane temperature distribution of the wafer is the same even in the subsequent run for growing the epitaxial layer, resulting in the same quality of epitaxial The layer can be allowed to grow.

The above-described cleaning is performed in a high-temperature atmosphere by supplying a cleaning gas such as HCl to remove deposits accumulated in the chamber during the run, and to remove the deposits.

However, there is a problem in that productivity decreases when the cleaning process is performed between each run, and when a plurality of runs are performed between cleaning processes in order to solve the problem of productivity deterioration, the wafer is inspected between the run immediately after cleaning and the run after the cleaning process. A difference in the quality of the epitaxial layer may occur due to an imbalance in the temperature distribution within the plane.

The present invention is a method for growing an epitaxial layer of a wafer in which the quality of the epitaxial layer grown on the wafer is uniform by making the in-plane temperature distribution of the wafer uniform in each run when a plurality of runs are performed in an epitaxial layer growing apparatus want to provide

An embodiment includes cleaning an epitaxial layer growing apparatus; growing an epitaxial layer on a wafer in the epitaxial layer growing apparatus; measuring an in-plane temperature distribution of an epitaxial layer grown on the wafer; Evaluating whether the quality of the epitaxial layer grown on the wafer satisfies a predetermined criterion; and changing a process temperature distribution of the epitaxial layer growing apparatus when the quality of the epitaxial layer grown on the wafer deviates from a predetermined standard.

The method of growing the epitaxial layer of the wafer may further include, after growing the epitaxial layer on the wafer in the epitaxial layer growing apparatus, evaluating whether the number of times the epitaxial layer grows is less than a predetermined standard.

If the number of times the epitaxial layer grows is less than the preset standard, the step of growing the epitaxial layer on the wafer in the epitaxial layer growing apparatus may be repeated.

If the number of times of growth of the epitaxial layer is equal to or greater than a predetermined standard, a step of measuring an in-plane temperature distribution of the epitaxial layer grown on the wafer may be performed.

In the changing of the process temperature distribution of the epitaxial layer growth apparatus, outputs of first lamps above the susceptor and second lamps below the susceptor in the epitaxial layer growth apparatus may be changed.

The first lamps above the susceptor in the epitaxial layer growth apparatus include 1-1 lamps in the central area and 1-2 lamps in the edge area, and the second lamps below the susceptor in the epitaxial layer growth apparatus 2-1 lamps in the central area and 2-2 lamps in the edge area may be included.

Changing the process temperature distribution of the epitaxial layer growth apparatus may include adding a first variable to the existing outputs of the 1-1 lamps and adding a second variable to the existing outputs of the 1-2 lamps, A third variable may be added to the existing outputs of the 2-1 lamps, and a fourth variable may be added to the existing outputs of the 2-2 lamps.

In the method of growing an epitaxial layer of a wafer according to the present invention, it is possible to grow an epitaxial layer of the same quality for each run by introducing a variable for the output of each lamp while omitting a cleaning process between each run.

1 is a diagram illustrating a method of growing an epitaxial layer of a wafer according to an embodiment of the present invention.
2 is a diagram illustrating an apparatus for growing an epitaxial layer of a wafer according to an embodiment.
3A is a diagram showing a temperature distribution within a surface of a wafer in a conventional method for growing an epitaxial layer of a wafer.
3B is a diagram illustrating a temperature distribution within a surface of a wafer in a method for growing an epitaxial layer of a wafer according to an embodiment.
4 shows the temperature distribution in each region of the wafer according to the beta value, that is, the value in which the outputs of the first and second lamps are changed in the above-described embodiment.
5 shows SFQR data for each run in Comparative Example 1 and Example 1.
6 shows ESFQR data for each run in Comparative Example 1 and Example 1.

Hereinafter, examples will be described in order to explain the present invention in detail, and will be described in detail with reference to the accompanying drawings to help understanding of the present invention.

However, embodiments according to the present invention can be modified in many different forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

In addition, relational terms such as "first" and "second", "upper" and "lower" used below do not necessarily require or imply any physical or logical relationship or order between such entities or elements. As such, it may be used only to distinguish one entity or element from another entity or element.

1 is a diagram illustrating a method of growing an epitaxial layer of a wafer according to an embodiment of the present invention.

The method of growing an epitaxial layer on a wafer according to the present embodiment includes cleaning an epitaxial layer growth apparatus (S110), growing an epitaxial layer on a wafer in the epitaxial layer growth apparatus (S120), Evaluating whether the number of growths of the epitaxial layer is less than a predetermined criterion (S130), measuring the in-plane temperature distribution of the epitaxial layer grown on the wafer (S140), and quality of the epitaxial layer grown on the wafer A step of evaluating whether the predetermined criterion is satisfied (S150), and a step of changing the process temperature distribution of the epitaxial layer growth apparatus (S160) are included.

2 is a diagram illustrating an apparatus for growing an epitaxial layer of a wafer according to an embodiment. As shown in FIG. 2, in the apparatus used in the method of growing an epitaxial layer of a wafer according to the present embodiment, a wafer is disposed on the susceptor 200 disposed inside a process chamber to form an epitaxial layer ( An epitaxial layer may be grown, and the first lamps 500 and the second lamps 600 may be disposed at upper and lower portions of the process chamber, respectively.

In addition, although not shown, thermometers may be provided at the upper and lower portions of the process chamber, but are not limited thereto.

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

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

Although not shown, a wafer vision area may be provided in the upper dome 100, and warpage of the wafer during the epitaxial layer deposition process may be observed through the wafer vision area.

A carrier gas such as hydrogen required to grow an epitaxial layer on a wafer and/or a raw material gas (or reaction gas) such as silane such as SiHCl ₃ or SiH ₂ Cl ₂ is introduced through the gas inlet (in), and the wafer An epitaxial layer may be formed thereon, and residual gas after formation of the epitaxial layer may be discharged through a gas discharge port (out). As shown, the gas inlet (in) and the gas outlet (out) may be formed to face each other, but are not limited thereto.

In addition, since the susceptor 200 is provided between the gas inlet (in) and the gas outlet (out), the gas inlet (in) and the gas outlet (out) are located at almost the same height as the upper surface of the susceptor 200. Source gas introduced through the gas inlet may flow along the surface of the wafer.

In order to control the temperature inside the process chamber, light is applied to the upper and lower regions of the susceptor 200 from the first lamp 500 and the second lamp 600 disposed on the upper and lower portions of the susceptor 200, respectively. Radiant heat emitted from the first and second lamps 500 and 600 may be transferred toward the wafer. In this case, the first lamp 500 may be referred to as a top lamp, and the second lamp 600 may be referred to as a bottom lamp.

At this time, among the first lamps 500 provided in the upper region of the susceptor 200, those provided in the central region are referred to as 1-1 lamps 500a, and those provided in the edge region are referred to as 1-2 lamps 500a. It can be classified as a lamp 500b, and among the second lamps 600 provided in the lower area, the one provided in the central area is referred to as the 2-1 lamp 600a, and the one provided in the edge area is referred to as the 2-2 lamp ( 600b) can be distinguished.

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

First, the inside of the epitaxial layer growing apparatus is cleaned. Since a silicon layer or other foreign materials may be deposited inside the epitaxial layer growing apparatus during the epitaxial layer growth process, the silicon layer or other foreign materials may be removed through a cleaning process.

Then, an epitaxial layer can be grown on the wafer in the epitaxial layer growing apparatus. In detail, an epitaxial layer may be grown as a thin film on a wafer on the susceptor 200 disposed inside the process chamber.

Then, it is evaluated whether the number of times of growth of the epitaxial layer is less than a predetermined criterion. That is, if the number of times the epitaxial layer grows is set to 5 times, for example, and the number of times the epitaxial layer grows is less than 5 times, the step of growing the epitaxial layer on the wafer in the epitaxial layer growing device is repeated again. can do.

In addition, when the number of epitaxial layer growths exceeds a predetermined standard, that is, when the number of epitaxial layer growths reaches 5 times, the in-plane temperature distribution of the epitaxial layer grown on the wafer may be measured. That is, when the growth of the epitaxial layer is completed, the temperature distribution in the center region and the edge region of the front and rear surfaces of the wafer may be measured by measuring the temperature distribution within the surface of the wafer.

In addition, it may be evaluated whether the quality of the epitaxial layer grown on the wafer satisfies a predetermined criterion. The quality of the epitaxial layer may be, for example, the thickness uniformity of the thin film or the presence or absence of defects.

When the quality of the epitaxial layer grown on the wafer satisfies a predetermined criterion, the process of growing the epitaxial layer on the wafer may be terminated.

In addition, when the quality of the epitaxial layer grown on the wafer does not satisfy the predetermined standard, the process temperature distribution of the epitaxial layer growing apparatus may be changed. In this case, the change in the process temperature distribution of the epitaxial layer growth apparatus may change the output of the first lamps above the susceptor and the second lamps below the susceptor in the epitaxial layer growth apparatus.

Specifically, a first variable is added to the existing outputs of the 1-1 lamps, a second variable is added to the existing outputs of the 1-2 lamps, and a third variable is added to the existing outputs of the 2-1 lamps. In addition, a fourth variable may be added to the existing outputs of the 2-2 lamps.

That is, before changing the output of the first and second lamps, assuming that the total output of the first and second lamps is 100 and the total output of the second lamps is A%, the total output of the first lamps is (100-A)% can be In addition, when the total output of the first lamps is 100, and the total output of the 1-1 lamps is B%, the total output of the 1-2 lamps may be (100-B)%. In addition, when the total output of the second lamps is 100, and the total output of the 2-1 lamps is C%, the total output of the 2-2 lamps may be (100-C)%.

Then, the changed output of the first and second lamps may be as follows. For example, if the first to fourth variables are alpha (α), beta (β), gamma (γ), and delta (δ), the total output of the 1-1 lamps is (B + alpha)%, The total output of the 1-2 lamps is (100-B+beta)%, the total output of the 2-1 lamps is (C+gamma)%, and the total output of the 2-2 lamps is (100-C+delta)% am.

By changing the output of each lamp in the above-described method, the temperature distribution in each region of the wafer is adjusted in a subsequent run, and the temperature distribution in the surface of the wafer is changed to improve the quality of the epitaxial layer to be grown. can

Figure 3a is a view showing the temperature distribution within the surface of the wafer in the conventional method for growing the epitaxial layer of the wafer, Figure 3b is a view showing the temperature distribution within the surface of the wafer in the method for growing the epitaxial layer of the wafer according to the embodiment am.

The vertical axis represents the temperature, and the horizontal axis represents the distance from the center of the wafer. In Comparative Example 1 of FIG. 3A, conventionally, the temperature distribution in each area of the wafer is different for each run, which can be attributed to the cleaning process being performed between each run. In Example 1 of FIG. 3B , after the cleaning process is performed before the first run as described above, the temperature distribution in each area of the wafer can be controlled to be substantially the same by adjusting the output of the lamps in each run.

Table 1 below shows the temperature change for each run in the central region, the middle region, and the edge region of the wafer in FIGS. 3A and 3B. The center area means the center area of the wafer, the middle area means the area spaced apart from the center area by about 75 millimeters, and the edge area means the edge area spaced apart by about 148 millimeters from the center area. The temperature of the wafer in the central region, the middle region, and the edge region is described, and the delta value represents the temperature difference between the central region and the edge region.

number of runs Central area (℃) Middle range (℃) Edge area (℃) Delta value (℃) Example 1 One 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 One 1130 1128.449 1138.531 -8.531 2 1130 1127.675 1136.625 -6.625 3 1130 1127.918 1136.435 -6.435

4 shows the temperature distribution in each region of the wafer according to the beta value, that is, the value in which the outputs of the first and second lamps are changed in the above-described embodiment 1. That is, 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 is shown.

And, Table 2 shows the temperature change for each run in the central region, the middle region, and the edge region of the wafer when the beta value is changed from +20% to -20%. The center area means the center area of the wafer, the middle area means the area spaced apart from the center area by about 75 millimeters, and the edge area means the edge area spaced apart by about 148 millimeters from the center area. It can be seen that the temperature of the edge region of the wafer mainly changes 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 upper portion of the wafer are increased or decreased. And, 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.

Beta value (%) Central area (℃) Middle range (℃) Edge area (℃) +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

5 shows SFQR data for each run in Comparative Example 1 and Example 1, and FIG. 6 shows ESFQR data for each run in Comparative Example 1 and Example 1.

SFQR (Site Flatness Front Least Square Range) represents the flatness of the entire front surface of the wafer, and ESFQR (Edge Site Flatness Front Least Square Range) represents the flatness of the front surface of the wafer, particularly in the edge region.

Compared to Example 1 (Appleid) in FIG. 5, Comparative Example 1 (Not Applied) has a large deviation in SFQR values for each run, and in FIG. 6, Comparative Example 1 (Not Applied) compared to Example 1 (Appleid) has It can be seen that the deviation of the ESFQR value is large in each run.

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 degraded, and thus the quality of the grown epitaxial layer may be degraded.

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

In the method of growing an epitaxial layer of a wafer according to the present invention, it is possible to grow an epitaxial layer of the same quality for each run by introducing a variable for the output of each lamp while omitting a cleaning process between each run.

Although the embodiments of the present invention have been described in more detail with reference to the accompanying drawings, the present invention is not necessarily limited to these embodiments, and may be variously modified without departing from the technical spirit of the present invention. . Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain, and the scope of the technical idea of the present invention is not limited by these embodiments.

Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The protection scope of the present invention should be construed according to the claims below, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

100: upper dome 150: lower dome
200: susceptor 210: main shaft
220a to 220c: support shaft 240a to 240c: lift pin
500: first lamp 500a: 1-1 lamp
500b: first-second lamp 600: second lamp
600a: 2-1st lamp 600b: 2-2nd lamp

Claims (7)

cleaning the epitaxial layer growth apparatus;
growing an epitaxial layer on a wafer in the epitaxial layer growing apparatus;
measuring an in-plane temperature distribution of an epitaxial layer grown on the wafer;
Evaluating whether the quality of the epitaxial layer grown on the wafer satisfies a predetermined criterion; and
and changing a process temperature distribution of the epitaxial layer growing apparatus when the quality of the epitaxial layer grown on the wafer deviates from a predetermined standard. According to claim 1,
After growing the epitaxial layer on the wafer in the epitaxial layer growing apparatus, the method of growing the epitaxial layer of the wafer further comprising the step of evaluating whether the number of times of growth of the epitaxial layer is less than a predetermined criterion. According to claim 2,
If the number of times the epitaxial layer grows is less than a predetermined standard, the step of growing the epitaxial layer on the wafer in the epitaxial layer growing apparatus is repeated. According to claim 2,
The step of measuring the in-plane temperature distribution of the epitaxial layer grown on the wafer if the number of times of growth of the epitaxial layer is equal to or greater than a predetermined standard. According to any one of claims 1 to 4,
The step of changing the process temperature distribution of the epitaxial layer growth apparatus,
A method for growing an epitaxial layer of a wafer by changing the output of first lamps above the susceptor and second lamps below the susceptor in the epitaxial layer growing apparatus. According to claim 5,
The first lamps above the susceptor in the epitaxial layer growth apparatus include 1-1 lamps in the central area and 1-2 lamps in the edge area, and the second lamps below the susceptor in the epitaxial layer growth apparatus A method for growing an epitaxial layer of a wafer including 2-1 lamps in a central area and 2-2 lamps in an edge area. According to claim 6,
The step of changing the process temperature distribution of the epitaxial layer growth apparatus,
A first variable is added to the existing outputs of the 1-1 lamps, a second variable is added to the existing outputs of the 1-2 lamps, and a third variable is added to the existing outputs of the 2-1 lamps. , A method for growing an epitaxial layer of a wafer in which a fourth variable is added to the existing output of the 2-2 lamps.

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