JP2003254741A - Measurement method, measurement device, manufacturing method for semiconductor epitaxial wafer, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of measuring evaluation information such as site flatness for every site in a single crystal thin film more easily in comparison with a conventional method based on three-dimensional shape measurement and capable of grasping the relationship between the site flatness and a film thickness distribution in association with each other, for example, in measurement of a semiconductor epitaxial wafer. <P>SOLUTION: Over the whole face of a thin film main surface in the semiconductor single crystal thin film, a plurality of film thickness measurement points 211 are decided, and in each of the film thickness measurement points 211, a film thickness of the semiconductor single crystal film is measured by an FT-IR and the like. Then, the thin film main surface is divided into a plurality of sites 221 each including a plurality of thin film thickness measurement points, and in each of the sites 221, several pieces of the semiconductor single crystal thin film evaluation information 222 and 223 specific to each of the sites 221 are formed on the basis of a thin film measurement value of the film thickness measurement point included in the corresponding site, and these pieces of information are outputted in the form of a site map. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor epitaxial wafer measuring method, a semiconductor epitaxial wafer measuring apparatus, a semiconductor epitaxial wafer manufacturing method, and a computer program.

[0002]

2. Description of the Related Art A silicon epitaxial wafer in which a silicon single crystal thin film (hereinafter simply referred to as "thin film") is formed on a surface of a silicon single crystal substrate (hereinafter simply referred to as "substrate") by a vapor phase growth method. Is a bipolar IC
It is widely used in electronic devices such as MOS and IC. When manufacturing an IC using a silicon epitaxial wafer, a well-known photolithography technique is adopted. In the photolithography technique, a pattern formed on a mask is exposed and transferred onto a photoresist layer formed on the main surface of a wafer through a reduction projection optical system of an exposure device. Focusing accuracy of exposure is important to ensure transfer accuracy.

For example, if the main surface of the epitaxial wafer is formed on an ideal plane, the focus of the exposure beam is focused on the plane to form a defocused reduced pattern over the entire main surface. be able to. However, the actual main surface of the epitaxial wafer always deviates from the ideal plane due to various factors described later. The deviation of the main surface from the ideal plane is quantitatively evaluated by the flatness. Flatness is a parameter that represents a geometrical deviation of a surface to be evaluated from a reference plane when a certain reference plane is defined, and the definition of the deviation (for example, the difference between the highest point and the lowest point or the absolute point There are various types depending on how the value plane or root mean square value) and the reference plane are defined, and they are used properly according to the purpose.

For example, when the beam is focused on the reference plane, blurring due to defocusing is small in the main surface area where the deviation from the reference plane is small, but defocusing occurs in the main surface area where the deviation is large. The impact is significant. On the main surface having poor flatness, the ratio of the area where such defocusing occurs becomes large, so that the accuracy of pattern transfer also deteriorates. Therefore, in order to improve the accuracy of pattern transfer, reducing the flatness of the main surface of the wafer is one of the important factors.

When the diameter of the epitaxial wafer is small, or when the pattern to be transferred is not very fine (for example, in the manufacture of discrete devices), the batch exposure method in which a single reference plane is set on the entire main surface is adopted. It may be done. However, this method is not applicable to the case where a fine pattern needs to be transferred with high accuracy, because the main surface area that largely deviates from the reference surface increases. Therefore, in this case, a partial exposure method (stepper method) is employed in which the main surface is divided into unit areas of a certain shape called sites, and a reference plane is defined for each site for focusing. In this case, what is the flatness of each site is a very important quality evaluation item of the epitaxial wafer. When measuring the flatness of each site, measure the height distribution of the surface for each site to determine the unique reference plane, calculate the deviation of the height distribution in the site from the reference plane, and obtain the flatness data. To get it.

[0006]

The causes of deteriorating the flatness of the main surface of an epitaxial wafer are broadly classified into those caused by problems of the substrate such as non-uniformity of the thickness of the substrate and polishing accuracy, and the film of single crystal thin film. There are two types, such as the thickness distribution, which are caused by problems in the thin film growth process. However, today, with the dramatic improvement in wafer processing accuracy, the deterioration of site flatness is caused by the unevenness of the film thickness of the grown single crystal thin film depending on the position within the main surface due to various factors. There are overwhelmingly many cases.

Nevertheless, in the field of manufacturing epitaxial wafers, the process control that organically combines the measurement of the site flatness and the measurement of the film thickness of the single crystal thin film has hitherto not been performed surprisingly. . For example,
In the case of a silicon epitaxial wafer, the film thickness measurement is performed by the well-known FT-IR method at a few measurement points determined independently of the site, whereas the flatness is completely unrelated to the film thickness measurement. Main surface of wafer 3
Dimensional shape measurement (for example, by a capacitance method, a laser interference method, an ultrasonic method, or an optomicrometer method) has been performed. However, this method requires too few film thickness data measured on one wafer to accurately grasp the relation between the site flatness and the film thickness, and the film thickness and flatness are separately measured. There is an inconvenience that must be done. On the other hand, it is possible to measure the three-dimensional shape of the main surface of the wafer before and after the growth of the single crystal thin film and obtain the film thickness distribution from the difference, but it is necessary to perform the three-dimensional shape measurement twice. The problem of is not solved.

The object of the present invention is to be able to measure the evaluation information for each site of a single crystal thin film, such as the site flatness, much more easily than the conventional three-dimensional shape measurement method. Semiconductor epitaxial wafer measuring method and semiconductor epitaxial wafer measuring apparatus capable of grasping the relationship between the site flatness and the film thickness distribution of a single crystal thin film in association with each other, and easily estimating factors such as the deterioration of the site flatness Another object of the present invention is to provide a semiconductor epitaxial wafer manufacturing method using the same, and a computer program for realizing the functions of the above-described measuring device on a computer.

[0009]

Means for Solving the Problems and Actions / Effects A method for measuring a semiconductor epitaxial wafer according to the present invention is a semiconductor in which a semiconductor single crystal thin film is epitaxially grown on a main surface of a semiconductor single crystal substrate as a base surface. The present invention relates to a method for measuring an epitaxial wafer, and in order to solve the above problems, a plurality of film thickness measurement points are defined over the entire thin film main surface of a semiconductor single crystal thin film, and at each film thickness measurement point, the semiconductor single film is measured. The film thickness measuring step of measuring the film thickness of the crystal thin film and the main surface of the thin film are divided into a plurality of sites each including a plurality of film thickness measuring points, and the film thickness measuring points included in the site are divided for each site. Based on the film thickness measurement value of
Site-specific thin film evaluation information creation process that creates site-specific thin film evaluation information that is the evaluation information of the semiconductor single crystal thin film unique to each site, and site-specific thin film evaluation information output process that outputs the created site-specific thin film evaluation information And are included.

The semiconductor epitaxial wafer measuring apparatus of the present invention is a semiconductor epitaxial wafer measuring apparatus in which a semiconductor single crystal thin film is epitaxially grown on the main surface of a semiconductor single crystal substrate as a base surface. In order to solve the above-mentioned problems, a film in which a plurality of film thickness measurement points are defined over the entire thin film main surface of the semiconductor single crystal thin film, and the film thickness of the semiconductor single crystal thin film is measured at each film thickness measurement point Thickness measuring device and semiconductor single crystal thin film,
Film thickness measurement value acquisition means for acquiring film thickness measurement values measured by a film thickness measuring device at a plurality of film thickness measurement points over the entire surface of the thin film; the thin film main surface includes a plurality of film thickness measurement points. Thin film evaluation information for each site, which is the evaluation information of the semiconductor single crystal thin film unique to each site based on the film thickness measurement value of the film thickness measurement point included in the site. And a site-based thin film evaluation information output device that outputs the created site-based thin film evaluation information, and a semiconductor epitaxial wafer evaluation device.

In the method and apparatus for evaluating a semiconductor epitaxial wafer according to the present invention, the main surface of the thin film is divided into sites, the film thickness is measured at a plurality of different points at each site, and the film thickness is measured. The thin film evaluation information for each site is created using the values, and also two-dimensionally output in a form corresponding to the site arrangement. That is, the film thickness measurement at multiple points is performed in a form associated with the site, and the thin film evaluation information for each site is created and output based on the film thickness measurement information. The method is simpler than the conventional method for measuring the three-dimensional shape, and the relation between the film thickness distribution and the thin film quality (for example, flatness described later) for each site can be grasped easily and precisely.

Further, the computer program of the present invention is a computer program for evaluating a semiconductor epitaxial wafer in which a semiconductor single crystal thin film is epitaxially grown on the main surface of a semiconductor single crystal substrate as a base surface. By installing the computer in a thin film main surface of the semiconductor single crystal thin film, film thickness measurement value acquiring means for acquiring film thickness measurement values measured at a plurality of film thickness measurement points over the entire thin film main surface. Is divided into a plurality of sites each including a plurality of film thickness measurement points, and for each of these sites, a semiconductor single crystal unique to each site is based on the film thickness measurement value of the film thickness measurement points included in the site. Site-specific thin film evaluation information creating means for creating site-specific thin film evaluation information, which is thin film evaluation information, and the created site-specific thin film evaluation information. And a site-specific membrane evaluation information output means for outputting in a form to correspond to the site two-dimensionally arranged,
It is characterized by functioning as an evaluation apparatus for a semiconductor epitaxial wafer provided with.

That is, the data of the film thickness measurement values measured at a plurality of points on the main surface of the thin film is acquired by the film thickness measuring device, and the thin film evaluation information for each site is created based on the data and the semiconductor epitaxial film is output. The functions of the wafer evaluation apparatus can be easily realized on the computer by installing the program into the computer.

Further, the first method of manufacturing a semiconductor epitaxial wafer of the present invention is to prepare site-specific thin film evaluation information for a semiconductor epitaxial wafer to be evaluated by the method of measuring a semiconductor epitaxial wafer of the present invention. It is characterized by comprising an evaluation step of evaluating each semiconductor epitaxial wafer based on information, and a selection step of selecting a semiconductor epitaxial wafer based on the evaluation result.

A second method of manufacturing a semiconductor epitaxial wafer according to the present invention comprises a thin film growth step of epitaxially growing a semiconductor single crystal thin film on the main surface of a semiconductor single crystal substrate as a base surface, and the above-mentioned method. By the semiconductor epitaxial wafer measuring method of the invention, the site-based thin film evaluation information is created for the obtained semiconductor epitaxial wafer, and an evaluation step for evaluating each semiconductor epitaxial wafer based on the information, and based on the evaluation result. Then, the conditions for performing the thin film growth step for manufacturing a semiconductor epitaxial wafer are adjusted.

By using the method for measuring a semiconductor epitaxial wafer of the present invention, thin film evaluation information for each site can be easily obtained by measuring the film thickness at a plurality of points at each site, and a single crystal for each site such as flatness can be obtained. The quality of the thin film can be evaluated easily and accurately. Further, based on the evaluation result, it is possible to easily identify the site having a defect in the quality of the single crystal thin film, for example, the average film thickness or the film thickness distribution state. According to the first method of manufacturing a semiconductor epitaxial wafer of the present invention, the semiconductor epitaxial wafer is selected based on the evaluation result, so that the quality of the shipped epitaxial wafer is improved and the defect rate is reduced. You can On the other hand,
According to the second method of manufacturing a semiconductor epitaxial wafer of the present invention, by site-based thin film evaluation information, it is possible to easily and easily understand at which site the quality defect of the single crystal thin film has occurred, and the occurrence status of the defect ( For example, from the location of the site where the failure occurred and the type of failure),
The cause can be easily specified. Then, by utilizing the results, the execution conditions of the thin film growth step when manufacturing the next semiconductor epitaxial wafer are adjusted so that the found defects are eliminated, and the occurrence of defects is prevented in advance. Or can be suppressed.

Hereinafter, the semiconductor epitaxial wafer measuring method of the present invention will be described in detail with regard to additional requirements. First, in the site-specific thin film evaluation information output step, the created site-specific thin film evaluation information can be two-dimensionally output in a form corresponding to the site arrangement. This makes it easier to intuitively grasp the site-specific thin film evaluation information by associating it with the actual site arrangement, and in particular, if there is a site where a problem has occurred, it is extremely easy to identify the position. You can As a result, it is possible to more easily identify the cause of the failure occurrence. This output may be displayed on a monitor screen or may be printed out on a medium such as paper by a printing device.

In the film thickness measuring step, an infrared beam may be incident on the main surface while being two-dimensionally scanned, and the film thickness may be measured by the infrared absorption spectrum method at each film thickness measuring point. In particular, the film thickness measurement by the infrared absorption spectroscopy is performed by the Fourier transform infrared spectrophotometer (Fourier Tran
A measurement method using a sformation InfraRed spectrophotometer (hereinafter referred to as FT-IR method) is suitable for the present invention because it has a wide track record as a method for measuring the film thickness of an epitaxial layer (silicon single crystal thin film) of a silicon epitaxial wafer. Can be used for In this method, an interferogram is measured by a Michelson interferometer, a normal infrared absorption spectrum waveform is obtained by Fourier transforming the interferogram waveform, and the film thickness is calculated from the spectrum waveform. . In order to measure the film thickness distribution for each site by measuring the film thickness by the FT-IR method while two-dimensionally scanning the main surface of the thin film, which is the surface to be measured, with the infrared beam that serves as the measurement probe. Convenient multi-point film thickness measurement can be performed easily. Especially in recent years, due to the high performance of arithmetic devices, there is a background that the processing speed of Fourier transform operation has been greatly improved.
Within a realistic processing time (for example, 30 seconds to 10 minutes), it is possible to measure the film thickness at 100 to 1000 points on one wafer.

If the site-specific thin film evaluation information is the site flatness information calculated using the film thickness measurement value, it can be directly utilized as a quality evaluation item of an epitaxial wafer for IC manufacturing or the like. Further, since it is possible to obtain the flatness information only by measuring the film thickness, it is not necessary to separately measure the flatness by a three-dimensional shape measuring device or the like, which is more efficient.

In this case, the semiconductor epitaxial wafer measuring method of the present invention is particularly effective, for example, when it is implemented as including the following steps. Film thickness measurement step: A plurality of film thicknesses of the semiconductor single crystal thin film of the semiconductor epitaxial wafer in which the semiconductor single crystal thin film is epitaxially grown on the main surface of the semiconductor single crystal substrate are determined over the entire main surface of the thin film. It is measured by the FT-IR method at the measurement point. Site flatness calculation step: The main surface of the thin film is divided into a plurality of sites each including a plurality of film thickness measurement points, and the site flatness is calculated for each of the sites using the measured film thickness. Site flatness output process: Calculated site flatness
Two-dimensionally output to the output device in a form corresponding to the site arrangement.

The film thickness of the semiconductor single crystal thin film of the semiconductor epitaxial wafer can be measured at a large number of points over the entire main surface of the thin film in a relatively short time by using the FT-IR method. By allocating the film thickness measurement values thus obtained to the sites partitioned on the main surface of the thin film, the flatness of each site can be easily calculated using the film thickness measurement values belonging to the site. . As a result, the flatness of each wafer site can be measured all at once as a part of the film thickness measurement without measuring the flatness separately by a three-dimensional shape measuring device or the like. Then, if the site flatness is two-dimensionally output (displayed or printed) in correspondence with the site arrangement, the site flatness distribution on the main surface of the wafer can be easily grasped at a glance. In particular, in a device manufacturing process such as an IC or the like, it can greatly contribute to the determination of whether a site is good or bad and to speedily grasp the focusing condition for each site during exposure.

The following method can be adopted to convert the measured film thickness in the site into the site flatness. That is, as shown in FIG. 13, at each site (S1, S1) of the semiconductor single crystal thin film EP epitaxially grown on the substrate WB.
2, S3, S4 ...) Film thickness measurement values (t1, t2, t3,
is regarded as the distance in the normal direction of the main surface DP of the thin film from the base surface BP, and the coordinates ((x1, y1), (x2, y2), (x3, y3) of the respective film thickness measurement points are taken. ),
(X4, y4): In order to distinguish from the film thickness direction coordinates described later,
Hereinafter, this will be referred to as in-plane direction coordinates) and the film thickness measurement values (t1, t2, t3, t4, ...) Corresponding to the profile points (π1, π2, π3, π4) on the main surface of the thin film.
,) And obtain those profile points (π1, π2, π
, Π4) are used to determine the reference planes (P1, P2, P3, P4 ...) For calculating the site flatness.

The base surface BP of the substrate WB used for manufacturing the epitaxial wafer is usually a mirror-polished surface obtained by chemical mechanical polishing, and its surface roughness level is higher than that of the epitaxially grown single crystal thin film. Much smaller (for example, the root mean square roughness of a mirror-polished main surface of a substrate used for a silicon epitaxial wafer is 1/100 to 1/1 of the film thickness order of a single crystal thin film).
It is about 0000). Therefore, if the surface roughness of the base surface BP is ignored with respect to the thickness of the single crystal thin film DP, it can be considered that the base surface BP is substantially flat in site unit. Therefore, the base surface BP can be used as a reference point (that is, the origin) of the position in the film thickness direction, and the film thickness direction coordinates of each profile point of the thin film main surface DP can be used as film thickness measurement values (t1, t).
2, t3, t4 ...) It becomes possible to substitute. Thereby, the film thickness measurement values (t1, t2, t3, t4 ...) Can be directly used as the film thickness direction coordinates of the profile points on the main surface of the single crystal thin film. This idea is based on SFQR
Alternatively, it is particularly effective when SFQD is used as the definition of flatness.

Once the shape profile data is obtained, a well-known definition can be adopted for the flatness itself. Definitions applicable to the present invention will be described below with reference to FIG.
Four or more profile points are set for each site, and the reference plane SP is determined as the least square regression plane of those profile points. In this case, the following two types can be defined as the site flatness: SFQR (Site Front Least sQares <site> Range) This is the difference between the maximum height and the minimum height viewed from the reference plane SP; SFQD (Site Front Least sQares <site> Deviati
on) The maximum value of the height displacement (absolute value) viewed from the reference plane SP is represented.

These definitions are effective for an exposure apparatus of a type (surface site alignment type) in which the optical axis is tilted to individually make a vertical incidence with respect to the tilted reference plane for each site. If the shape of the site surface is flat, the calculated flatness is also small (that is, the inclination of the site surface and the position in the height direction do not affect the flatness). And since the shape profile of the site itself is used for setting individual reference planes, there is no effect even if the substrate has warpage or thickness distribution,
As long as the accuracy of the film thickness measurement value is secured, there is an advantage that sufficiently reliable flatness data can be obtained. That is,
Even if the substrate thickness varies from site to site, it can be considered that the substrate thickness is almost the same within the same site. Therefore, the influence of the difference in substrate thickness between the sites or the warp only causes the individual site surfaces to move in parallel or rotationally with the reference surface, and does not affect the calculated flatness. It is to be noted that the profile points (that is, the film thickness measurement points) are determined to be 4 points or more for each site because 3 points are the minimum required for determining the reference plane, and the height deviation is obtained as a finite non-zero value. It depends on the situation that one or more degrees of freedom are required (the same applies to SFLR and SFLD described later).

Regardless of the site, three or four or more profile points are extracted over the entire main surface of the thin film, and the reference plane is determined by using the extracted profile points. In this case, the following four types can be defined as the site flatness: SF3R (Site Front 3points <global> Range) Common to each site using three non-collinear profile points on the thin film main surface. The reference plane SP (three-point reference plane) is defined, and it is the difference between the maximum height and the minimum height viewed from the reference plane SP; SF3D (Site Front 3points <global> Deviatio
n) The same reference plane SP as SF3R is used, and it is expressed by the maximum value of the height displacement (absolute value) seen from the reference plane SP; SFLR (Site Front Least sqares <global> Rang
e) A reference plane SP common to each site is defined as a least-squares regression plane using four or more profile points on the main surface of the thin film (a best fit reference plane is used if all the profile points are used), and the reference plane is set. It is the difference between the maximum height and the minimum height seen from SP; SFLD (Site Front Least sqares <global> Devia
tion) A reference plane SP similar to SFLR is used, and is represented by the maximum value of the height displacement (absolute value) viewed from the reference plane SP.

In these definitions, the reference plane is set so as to extend over a plurality of sites on the entire main surface of the thin film. Therefore, when the thickness of the substrate is greatly different between the sites or the substrate is largely warped, the flatness calculation results are different even for wafers having the same film thickness measurement value distribution. This is because these definitions have been devised as being consistent with a simple exposure method (surface global alignment method) in which the optical axis adjustment and focusing are performed only once with respect to the common reference plane. Therefore, this definition can be used only for epitaxial wafers that have a substrate with a substantially constant thickness and a small warpage, or epitaxial wafers whose substrate thickness distribution and warpage have been measured in advance. become. In the latter case, the profile point data is converted into the in-plane coordinate (x
i, yi) is a three-dimensional coordinate point ((x1, y1, z1), in which a value zi (= ti + t + δ) obtained by adding the substrate thickness t and the warp displacement δ to the film thickness measurement value ti is incorporated as the z coordinate.
(X2, y2, z2), (x3, y3, z3), (x
4, y4, z4) ...), the flatness can be calculated.

Using the main back surface of the semiconductor single crystal substrate as a reference plane, the total of the film thickness measurement value and the thickness of the semiconductor single crystal substrate is
Assuming that the distance is the normal direction of the main surface of the thin film from the reference plane, the profile points of the main surface of the thin film are 3 points or more for each site based on the coordinates of each film thickness measurement point and the corresponding film thickness measurement value. Ask. In this case, the site flatness can be defined as one of the following two types using the profile points: SBIR (Site Back-side Ideal Range) The back surface of the wafer is suction-fixed by a chuck to flatten the warp, It is the difference between the maximum height and the minimum height seen from the reference surface SP with the flattened back surface as the reference surface SP; SBID (Site Back-side Ideal Deviation) A focal plane FP that is parallel to the reference plane SP and that minimizes the total distance from the profile points is defined for each, and is represented by the maximum value of the height displacement (absolute value) viewed from the focal plane FP.

In this definition, the influence of warpage can be neglected due to the chuck on the back surface of the substrate. However,
If the substrate thickness varies significantly between sites,
Similarly, an epitaxial wafer having a substantially constant thickness, or a wafer whose thickness distribution is measured in advance will be limited. In the latter case, the data of the profile point is incorporated into the in-plane coordinate (xi, yi) of the film thickness measurement point as the z coordinate of the value zi (= ti + t) obtained by adding the substrate thickness t to the film thickness measurement value ti. 3D coordinate points ((x1, y1, z1), (x2, y
2, z2), (x3, y3, z3), (x4, y4, z
4) The flatness can be calculated by expressing it as a set.

The thin film evaluation information for each site can be effectively used as the film thickness distribution information for each site by simply outputting the film thickness measurement values at a plurality of points for each site. That is, the thin film evaluation information for each site may be film thickness distribution information within the site.

The site-specific thin film evaluation information can be information relating to the uneven shape of the main surface of the thin film within the site. If a curved site surface with severe irregularities is formed, a region that is out of focus during exposure (that is, a region that is out of focus) increases in the site, and the probability of failure during IC manufacturing increases. Therefore, if the information on the unevenness is output as the site-specific thin film evaluation information, it is possible to easily perform defect prediction and process improvement for defect prevention. In relation to the flatness described above, SFQD and S
When FQR is used as the definition of flatness, the larger the degree of unevenness, the larger the value, and conversely, if the degree of unevenness is small, the value of flatness becomes small no matter how the position of the surface itself changes. Therefore, there is an advantage that the relationship with the flatness evaluation can be easily grasped.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 11 conceptually shows a cross-sectional structure of a silicon epitaxial wafer (hereinafter, also simply referred to as a wafer) to which the present invention is applied. The wafer W is obtained by epitaxially growing a silicon single crystal thin film EP on one main surface of a silicon single crystal substrate WB by a known vapor phase growth method. As shown in FIG. 12, the main surface of the silicon single crystal thin film EP is virtually divided into a grid pattern by a plurality of square sites SF and SP. The peripheral portion of the main surface of the wafer W is a region where the flatness is likely to be deteriorated due to surface sagging during polishing, non-uniformity in film thickness of the epitaxially grown silicon single crystal thin film EP, and the flatness standard is not applied. The peripheral part exclusion area EE is distinguished from the flatness application area FQA inside thereof. Then, in the present embodiment, of the sites SF and SP, only the site SF which entirely belongs to the flatness applicable area FQA is evaluated for flatness.

FIG. 1 shows a semiconductor wafer measuring apparatus (hereinafter also simply referred to as a measuring apparatus) 10 according to an embodiment of the present invention.
It is a block diagram which shows the electric constitution of 0. Measuring device 10
0 is roughly classified into a film thickness measuring device 150 for measuring the film thickness of the silicon single crystal thin film EP of the wafer W, and a film thickness measurement value measured from the film thickness measuring device 150, and
This is composed of two elements: an evaluation device 200 for processing and outputting the site-specific thin film evaluation information.

The film thickness measuring device 150 has a control computer 111 and a measuring system 101 connected to the control computer 111.
The control computer 111 includes an I / O port 108, a CPU 104, a ROM 105, and a RAM 10 connected to the I / O port 108.
6. Hard disk drive (hereinafter,
An HDD (abbreviated as HDD) 107, and a keyboard 109 and a mouse 110 as input devices are connected. HD
In D107, a control program 107a that controls the operation of the film thickness measuring device, and data of an interferogram from a waveform measuring unit 11 to be described later are fetched, and Fourier transform is performed on this to obtain an infrared absorption spectrum waveform, and the spectrum thereof is obtained. A data acquisition / film thickness analysis program 107b for calculating the film thickness of the silicon single crystal thin film EP from a waveform based on a known method, and a film thickness distribution data file in which the obtained film thickness calculated value is stored in association with the measurement position coordinates. 107c
Is remembered. Further, the RAM 106 is formed with work areas 106a and 106b for the control program 107a and the data acquisition / film thickness analysis program 107b, and a storage area 106c for the film thickness distribution data file.

Next, the measuring system 101 includes the waveform measuring section 11
And a drive unit for scanning the waveform measuring unit 11 on the main surface of the wafer W. As shown in FIG. 2, the waveform measuring unit 11 has an infrared light source and a Michelson interferometer that separates and irradiates an infrared beam from the infrared light source into two incident beams having different optical path differences. System 14
And a detector 15 for detecting an interference signal formed by the reflected lights of the two incident beams. On the other hand, the drive unit two-dimensionally scans and drives the waveform measurement unit 11 along the main surface of the wafer. As this scanning method, it is also possible to adopt an XY scanning method based on a rectangular coordinate system, but in the present embodiment, two-dimensional scanning with an infrared beam is performed within the plane with the center of the main surface of the thin film as the origin. R-θ scanning is performed in two directions, the radial direction R and the in-plane circumferential direction θ.

In a silicon epitaxial wafer manufactured by a single-wafer vapor phase growth apparatus which has become mainstream in recent years, a silicon single crystal thin film is grown while rotating the wafer on a susceptor. Therefore, the film thickness distribution is basically , Although it tends to be uniform in the wafer circumferential direction,
In the radial direction, it tends to fluctuate under the influence of temperature, distribution of the source gas flow, and surface sagging of the polished main surface of the substrate. To accurately and efficiently grasp such a tendency, the distance between the film thickness measurement points in the circumferential direction is changed according to the radial position, such as by making the distance between the film thickness measurement points closer in a region where the problem of film thickness variation is likely to occur. It is effective to change
In this case, the arrangement of the measurement points naturally has regularity in the wafer radial direction (R) and the circumferential direction (θ). Therefore, R-θ set on the main surface of the wafer
The use of polar coordinates makes it possible to set measurement points more intuitively and easily. And in response to this,
By performing the R-θ scan of the infrared beam as described above, the coordinate information of the set measurement point can be directly used for the control data of the driving unit, which not only facilitates the programming of the scanning drive control, but also It is also advantageous from the viewpoint of improving the processing speed. Further, unnecessary movement of the scan-driving waveform measuring unit 11 is reduced, and the cycle time required for measuring the film thickness distribution of one wafer can be shortened.

As shown in FIG. 2, the drive unit in this embodiment includes an R drive motor 13 and a θ drive motor 17. The waveform measuring unit 11 includes a base 1 to which a screw shaft 12 is screwed.
1b, screw shaft 1 by R drive motor 13
By driving and stopping the rotation of No. 2, as shown in FIG. 3, the waveform measuring unit 11 linearly moves along with the base 11b along the guide 10 so that the waveform measuring unit 11 can be arbitrarily positioned in the R direction. Further, the wafer W is the wafer support table 1
6 is mounted on the wafer 6, and the wafer support table 16 is rotationally driven in the reverse θ direction by the θ drive motor 17, so that the waveform measuring unit 11 makes an arbitrary angle θ with respect to the wafer W.
Relatively driven so that it can be positioned.

The R drive motor 13 and a pulse generator (hereinafter referred to as R-PG) 114 and a pulse generator (hereinafter referred to as θ-PG) 116 for detecting θ servo control and rotational angle position are included. The R drive motor 13 and the θ drive motor 17 are connected to the I / O port 108 of the control computer 111 via motor drivers (not shown), respectively, and are driven and controlled by executing the control program 107a.

The interference signal formed by the reflected lights of the incident beam on the wafer surface is detected by the detecting section 15 as described above. By changing the position of the movable mirror of the Michelson interferometer provided in the light projecting unit 14 with time, the two infrared beams are incident on the main surface of the wafer while the optical path difference is continuously changed. If the incident infrared light is a monochromatic light, the interference intensity is maximum when the optical path difference is an integral multiple of the wavelength, and the interference intensity is minimum when the half-wave phase shifts from it, so the detected waveform of the reflected interference light is It becomes a sine wave with the infrared wavelength as one cycle. In the actual measurement, since an incident infrared ray having a continuous spectrum form of a certain wavelength range is used, the interferogram which is the detection waveform of the reflected interference light shows that the monochromatic light interference waveforms of various wavelengths are infrared rays of the measurement object. The intensity distributions that reflect the absorption behavior are superimposed. Therefore, the infrared absorption spectrum of the measurement object can be obtained by Fourier transforming the interferogram. It is known that the infrared absorption spectrum of a silicon epitaxial wafer by FT-IR has a maximum amplitude of infrared reflectance at a certain wave number, and has an attenuated sinusoidal waveform in which the amplitude gradually decreases as the wave number increases. The thickness of the silicon single crystal thin film can be calculated from the wave number period.

In FIG. 1, the input signal from the waveform measuring unit 11 is the interferogram waveform signal from the light receiving unit 15 in FIG. 2, and the CPU 10 of the control computer 111.
In step 4, the data acquisition / film thickness analysis program 107b is executed to acquire this as digital waveform data via a D / A converter (not shown). Then, Fourier transform is applied to the waveform data to obtain an infrared absorption spectrum, the film thickness of the silicon single crystal thin film is calculated from the period of the attenuation waveform, and the film thickness distribution data file 107c is associated with the measurement point coordinates, Remember.

Next, the evaluation device 200 uses the I / O port 2
08 and a CPU 201, a ROM 202 connected to the 08,
The RAM 203, the HDD 204 as a storage device, the mouse 206 and keyboard 207 as an input device, and the monitor 205 as a display device are configured as a computer, and the communication interfaces 209 and 112 are provided.
A communication line (or a communication network such as LAN) 220 is connected to the control computer 111 of the film thickness measuring device 150 via the.

In the HDD 204, the film thickness distribution data file 204b acquired from the film thickness measuring device 150 side via the communication line 220 and the acquired film thickness distribution data file are evaluated, and the result is displayed on the monitor 105. Data processing / display program 204a for
An evaluation result data file 204c showing the evaluation result obtained by the processing is stored. Also, the RAM 20
3 includes a work area 203a for the data processing / display program 204a and a film thickness distribution data storage area 203.
b, a display memory 203c for displaying the evaluation result in the form of a site map, and a storage area 203d for the evaluation result data are formed. In this way, the evaluation device 20
By executing the data processing / display program 204a, 0 functions as three means of the film thickness measurement value acquisition means, the site-based thin film evaluation information creation means, and the site-based thin film evaluation information output means in the claims. The data processing / display program 204a is installed in the computer of the evaluation device 200 by being recorded in a storage medium such as a CD-ROM 209a and read out via the CD-ROM drive 209. Alternatively, the program may be installed by downloading via a communication line. In both cases, the computer is evaluated by the installation.
It can function as 0. That is, it corresponds to the embodiment of the computer program of the present invention.

The film thickness measuring device 150 to the evaluation device 2
It is needless to say that the transfer of the film thickness distribution data to 00 may be performed via an external storage medium such as a floppy (registered trademark) disk. Further, the function of the evaluation device 200 can be integrated into the control computer 111 of the film thickness measurement device 150.

The flow of the operation of the measuring apparatus 100 will be described below with reference to the flowchart. FIG. 5 shows a processing flow in the film thickness measuring device 150. This processing is performed by the CPU 104 of the control computer 111 using the work areas 106a and 106b of the RAM 106 to execute the measuring device control program 107a and the data acquisition / analysis program 107b. First, in S1, wafer specific data such as the product number, lot number, and manufacturing date of the wafer to be measured is input.
Next, in S2 and S3, the wafer is mounted on the holder of the apparatus, and when the mounting is completed normally, the process proceeds to S4, the R drive motor 13 and the θ drive motor 17 are operated, and the waveform measuring unit 11 is set to the origin O. To move. As shown in FIG. 4A, in the present embodiment, the origin O is set at the center of the wafer main surface, the wafer radial direction is defined as the R direction, and a reference line passing through the origin O (matched with the x-axis in the figure). Radial R from
The angle formed by is defined as θ.

In S5 of FIG. 5, the waveform measuring unit 11 is set to
The R direction position Rk is moved to the first measurement position R1. Further, in S6, the θ direction position θk of the waveform measuring unit 11 is set to the first measurement position (θ coordinate of the film thickness measurement point) θ1.
As shown in FIG. 4B, the measurement positions 211 are set on the wafer main surface 212 at equal intervals in the circumferential direction along a concentric path CL having the origin O as a common center. . In this case, each circular path CL from the origin O
The distance to is given by Rk and R1 is either the outermost or innermost path position.
For example, in the present embodiment, the waveform measuring unit 11 is sequentially moved from the innermost path to the outer path.

When the position of the circular path CL is designated by the value of R, the circumferential direction along the path CL, that is, the θ direction,
The FT-IR profile is sequentially measured while moving and stopping the waveform measuring unit 11 at equal angular intervals Δθ (see FIG. 4A). Specifically, in S6, the waveform measuring unit 11 is moved to the first measurement position θ ₁ , and in S7, FT−
Perform IR profile measurement. As described above, this processing includes the detection of the interferogram by the infrared beam irradiation and the Fourier transform processing of the detected waveform. Then, in S8, the attenuation waveform period of the obtained FT-IR profile is read, and, for example, the HDD 107 (see FIG. 1 for hardware configuration requirements: the same applies hereinafter).
The film thickness is calculated with reference to a table or a function that stores the relationship between the film thickness and the waveform period stored in the. In S9, the calculated film thickness is stored in the film thickness distribution data storage area 106c in association with the film thickness measurement point coordinates (R, θ).

When the measurement at one measurement point is completed, S1
In step 1, the position in the θ direction is moved from the current film thickness measurement point position θ _k to the next film thickness measurement point position θ _{k + 1,} and the processing from S7 onward, that is, the FT-IR measurement and the storage of the obtained film thickness data are performed. repeat. However, if θ _k has already reached the final measurement position θ _N in S10, the next circular path CL
In order to move to the above measurement, the R-direction position is moved from the current position R _k to the next measurement position (R coordinate of the film thickness measurement point) R _{k + 1} , the process returns to S6, and the θ-direction position is set to the initial position θ1.
The following processing is repeated. Then, theta _k measurements and end it if it reaches the final measurement point position R _N in S12, the process proceeds to S14, the film thickness measurement point coordinates stored in the RAM106 (R, θ) and the film thickness data Of the film thickness distribution data 106c is stored in the HDD 107 as a film thickness distribution data file 107c shown in FIG. 8 in association with the wafer identification data.

When it is difficult to make a difference in the film thickness distribution or the tendency of occurrence of abnormalities depending on the area of the main surface of the wafer, it is desirable to set film thickness measuring points at a uniform density on the entire surface of the wafer. Specifically, when the measurement is performed by the R-θ scan as described above, the distance between the film thickness measurement points in the θ direction (= R
Δθ (angle unit: radian) can be set to be the same for all circular paths CL, for example. Further, the arrangement intervals of the circular paths CL in the R direction can be set substantially evenly. Furthermore, instead of R-θ scanning, x at equal intervals is used.
The -y scanning method may be used.

However, depending on the method of the vapor phase growth apparatus used for manufacturing the epitaxial wafer, there may be a significant difference in the film thickness distribution width and the frequency of occurrence of abnormalities depending on the region of the wafer main surface. In this case, the set density of the film thickness measurement points can be changed according to the region. Specifically, for areas where the film thickness distribution width is large or where the frequency of occurrence of film thickness abnormalities is expected to be relatively high, it is necessary to increase the set density of film thickness measurement points for accurate evaluation. Is effective in. For example, when using equipment such as a single-wafer type vapor phase growth furnace in which the width of the film thickness distribution becomes large in the outer peripheral area of the main surface of the wafer and the frequency of occurrence of film thickness abnormalities and defects is likely to increase, FIG. As shown in b), it is desirable to set the film thickness measurement points 211 so that the intervals are closer in the peripheral portion than in the inside of the main surface of the thin film. In particular, R-θ
If the scanning method is adopted, there is an advantage that the distance between the film thickness measurement points 211 in the peripheral portion can be easily dealt with by closely setting the distance in the θ direction. In FIG. 4B, the distances between the film thickness measurement points 211 in the peripheral portion are set to be dense in the peripheral portion also in the R direction. Such an interval setting can be easily determined by referring to the interval setting data 201 shown in FIG. 7, for example. The data 201 indicates that the circular path CL is located in the R-direction positions R1, R2,
.., Rf and the corresponding θ-direction intervals are converted into the rotation angles of the θ drive motor 17, Δθ1, Δθ2.
.., θf.

The above film thickness distribution data file 107c
Is transmitted to the data processing computer 200 by the communication line 220 via the communication interfaces 209 and 112, and is temporarily stored in the HDD 204. Then, it is read out as needed to analyze the flatness and the like, and the result is displayed on the monitor 205 in a site map format. The result can also be output from the printer 210. Figure 6
Shows an example of the flow of the processing. This processing is performed by the CPU 201 of the evaluation device 200 using the work area 203a of the RAM 203 to execute the data processing / display program 204a.

In S101, the wafer specific data is input by the keyboard 207 or the mouse 206. In S102, the film thickness distribution data corresponding to the input wafer specific data is retrieved by searching the HDD 204. The read film thickness distribution data is, as shown in FIG. 8, film thickness measurement values t1 ′, t2 ′,
, Tn 'are stored in a form associated with the measurement point coordinates displayed in the R-θ coordinate system. The measurement point coordinates are S
At 103, as shown in FIG. 4A, the R-θ coordinate system is converted into an xy rectangular coordinate system convenient for site map display, and the film thickness measurement values are further sorted into an xy two-dimensional array. (The measured film thickness after sorting is t1, t2, ..., t
n).

Next, in FIG. 6, the routine proceeds to S104, where x-
Set the site on the y coordinate. With the center of the wafer as the origin, a plurality of square sites SF are arranged and set in a grid pattern in the flatness application region FQA. Each site has coordinates (xa, ya) and (xb, y) of four vertices of a square.
a), (xa, yb), (xb, yb) (where a <
It can be specified in b). Then, in S104, it is determined to which of the set sites the respective measurement point coordinates (x, y) of the film thickness distribution data converted into the xy two-dimensional array belong, and as shown in FIG. , Measurement point coordinates (xi, yi), film thickness measurement value ti (i = 1, 2, ...,
n) and the site number Sj (i = 1, 2, ..., M) are associated with each other to create a film thickness distribution data file 204b. Whether or not the measurement point coordinates (xi, yi) belong to a site is determined by determining the four vertices of the site as (xa, yi).
a), (xb, ya), (xa, yb), (xb, y
b), xa <xi <xb and ya <yi <y
It can be easily determined by whether or not b is satisfied. It is to be noted that the boundary between two adjacent sites is defined as belonging to one of those sites, and when the measurement point coordinates (xi, yi) are located on the boundary, the site to which the boundary belongs Treated as being located inside.

The process from S105 to S125 is the site-specific thin film evaluation information creation process, specifically, the flatness analysis process for each site. In the present embodiment, as the process of creating the thin film evaluation information for each site, the SFQR and SF described above are
Two flatness parameters of the QD are calculated, information on the uneven shape of the main surface of the thin film in the site is created, and the site-specific judgment is performed according to the result. In S105, the site number Sj is set to the initial value S1. This is a step of selecting / designating a site to be analyzed, and S106 to S123 are a loop for analyzing the selected site. By setting Sj to the next number in S125 and returning to S106, the flatness analysis of the sites proceeds in numerical order, and it is confirmed in S124 that the process of the last site (number Sm) has been completed. It is designed to escape the loop.

The processing in the loop is as follows. S1
At 06, the film thickness data in the selected site is read from the film thickness distribution data of FIG. In S107, the maximum film thickness value tmax and the minimum film thickness value tmin are obtained by a known maximum / minimum determination algorithm. In S108, each film thickness data is set to the (x, y) coordinate of the film thickness measurement point, and the film thickness measurement value t is set to z.
Treated as (x, y, t) three-dimensional data points (hereinafter also referred to as profile points on the main surface of the thin film or simply profile points: position vector is π) combined as coordinate values, and known to each film thickness data point. A three-dimensional least squares regression is performed to determine the site reference plane SP shown in FIG. 9 (unit normal vector ν is calculated). Then, S109
Then, the difference between the maximum height and the minimum height of the main surface height in the normal direction of the site reference plane SP is calculated as SFQR. Although there are separate true positions on the main surface that give the maximum height and the minimum height, in the present embodiment, the measurement point positions of the maximum film thickness value tmax and the minimum film thickness value tmin that have already been obtained are used instead. , Tmax and tmin are calculated as the difference between the coordinate orthogonal projection values in the normal direction. In this case, the position vectors of the profile points that give tmax and tmin are respectively πmax
And πmin, the SFQR can be calculated by using the scalar product (represented by the symbol “·”) with the normal vector ν described above, SFQR = ν · πmax−ν · πmin.

On the other hand, in S110, the distance between each profile point (x, y, t) in the site and the site reference plane SP is obtained, and the maximum value of the distance is determined as SFQD. The following can be used as the calculation algorithm.
When the equation of SP is expressed by lx + my + nz + q = 0 ..., This is translated by −q / n in the z direction, and a plane SP ′ (lx + my + nz = passes the coordinate origin.
Consider 0). Then, each profile point π is set to -q / n
Point π ': (x, y, tq
/ N) and the distance between SP 'and the plane S before movement to be obtained
Equal to the distance between P and the film thickness data point π. Since it is a parallel movement, the normal vector of SP and SP ′ remains ν, and therefore the distance d is calculated by d = | π ′ · ν |. The maximum value dmax of this d is SFQD.

Next, S111 to S113 are processes for creating information on the uneven shape of the main surface of the thin film. In the present embodiment, the following processing is adopted as an algorithm for easily determining the unevenness. First, as shown in FIG. 15A, four or more profile points of the main surface of the thin film based on the measured film thickness are obtained for each site (assuming that they are not on the same straight line), and based on these profile points. Then, the reference plane SP of each site is set (already determined by the processing up to this point). Next, at a predetermined unevenness determination position k in each site, either the profile point directly determined by the film thickness measurement value or the estimated profile point k ′ obtained by interpolation estimation from another profile point is unevenly formed. Used as a judgment point. Then, as shown in FIG. 15B, when the unevenness determination point is projected from the reference surface by a certain distance γ or more, the shape of the thin film main surface of the site is convex (indicated by “∩”). Judge that there is. In addition, FIG.
As shown in (c), it is determined that the shape of the main surface of the thin film at the site is concave (indicated by “∪”) when the site is retracted by a certain distance α or more.

In this embodiment, in S111, as shown in FIG. 15A, the center J ((x
The point on the reference plane SP corresponding to a + xb) / 2, (ya + yb) / s, 0), that is, the z-direction projection point of J to SP is obtained as the unevenness determination reference point k. Next, in S112, the three profile points A, B, C closest to k are
And the z-direction projection point of the unevenness determination reference point k on the plane determined by the three points is defined as the unevenness determination point k ′. If A,
If any of B and C matches the unevenness determination point k ′, the matching point, that is, the profile point itself obtained by film thickness measurement is the unevenness determination point. On the other hand, if they do not match, the unevenness determination point k ′ is an estimated profile point obtained from A, B, and C.

Next, in S113, the difference Δz≡zk′−zk ... between the z-coordinate values of the unevenness determination point k ′ and the unevenness determination reference point k is calculated. The determination process is performed from S114 onward.
If Δz is equal to or larger than + γ, the unevenness display type value Ci (see FIG. 10) is set to 2 (convex) in S115.
Further, if Δz is −α or less in S116, S11
In step 7, the unevenness determination flag Ci is set to 1 (concave).
If −α <Δz <+ γ, Ci in S118
Is set to 0 (flat).

Further, S119 and the subsequent steps are flatness judgments. In S119, the calculated value of SFQR (or SFQD) is compared with a reference value stored in advance, and if it is equal to or more than the reference value, it is determined as a defect. In this case, the flatness determination flag Fi is set to 0 (good) in S122, and the display color SCi of the site is set to 0 for the site display described later.
Set to (standard color). On the other hand, if it is less than the reference value, it is determined as defective. In this case, the flatness determination flag Fi is set to 1 (defective) in S122, and the display color SCi of the site is set.
Is set to 0 (warning color).

The results obtained by the above processing are collected and stored in the evaluation result data file 204c as site-specific thin film evaluation information in a form associated with the site number, as shown in FIG. The content of the site-specific thin film evaluation information is not limited to this. For example, only one of SFQR and SFQD may be calculated, or another flatness parameter may be used. The unevenness determination may be a process not particularly performed.

Returning to FIG. 6, the output process is performed from S126. As shown in FIG. 16, a display window DW is opened on the screen of the monitor 205, a film thickness distribution display area is secured in the display window DW, and a film thickness map 2 at each measurement point position is obtained.
Display 10 Specifically, a display coordinate system is set in the film thickness distribution display area, and a film thickness display figure is displayed at a position representing a measurement point position in the display coordinate system in a manner that the size of the film thickness can be grasped. In the present embodiment, a circular film thickness display graphic is used, and the size of the film thickness is represented by the radius value of the film thickness display graphic. Specifically, as shown in S126 of FIG. 6, the center of the film thickness display figure is set at the measurement point position, and the film thickness value t
Draw a circle with a radius r0 proportional to and draw the inside. By doing so, as shown in FIG. 16, a region where the film thickness is large and a region where the film thickness is small on the main surface of the wafer can be recognized at a glance by the size of the film thickness display figure, and the film thickness distribution can be intuitively grasped. Can be done

As shown in FIGS. 17, 18 and 21, the film thickness map 210 can also represent the size of the film thickness by the difference in color and shade. In FIG. 21, in the film thickness map 210 ′, the interpolated and estimated film thickness lines GL are displayed, and regions between the film thickness lines are colored and shaded,
This makes it easier to understand the film thickness distribution. Further, in the display window DW, the film thickness distribution profile 21 along the profile setting line defined on the main surface of the wafer is shown.
3, 214 is also displayed. In this embodiment,
The profile setting line is defined as a line AA passing through the center of the wafer and a line along the outer peripheral edge of the wafer main surface, and both are profile curves using the film thickness measurement data on the line (or closest to the line). Generate a·
it's shown. Further, in FIGS. 17 and 18, the film thickness map 210 is displayed as a three-dimensional stereoscopic display.

Further, as shown in FIG. 16, the film thickness value may be displayed by numbers. In this embodiment, the film thickness values at the corresponding positions on the main surface of the wafer, that is, at the center, the middle in the radial direction, and the outer circumference, are indicated by numbers. According to this method, the absolute value of the film thickness can be accurately grasped, and if it is used together with the display by the film thickness display figure as shown in FIG. 16, not only the relative distribution state of the film thickness but also the absolute value It is possible to get a more accurate grasp of the level.

Returning to FIG. 6, the site map display processing is performed in S127. That is, the created site-specific thin film evaluation information is two-dimensionally output in a form corresponding to the site arrangement. Specifically, in the site map display area set in the display window DW, the site map 2 in which the site figures 221 corresponding to the respective numbers are arranged in a grid pattern.
Display 20. As shown in FIG. 10, flatness determination results (flag Fi) and unevenness determination results (flag C) for each site.
Since various measurement results and judgment results regarding the site such as i) are stored as thin film evaluation information for each site, a predetermined one is appropriately selected from the thin film evaluation information for each site, It is displayed in each site graphic 221. In this embodiment, the flatness calculation result (SFQR or SFQD) 222 and the number of data points 223 in the site are set.
However, the present invention is not limited to this, and for example, as shown in FIG. 19, the maximum and minimum values (tmax and tmin) of the film thickness in the site and the range ΔtR (≡tmax-tmin).
20 may be displayed, or as shown in FIG. 20, the average value tAVE and the standard deviation σt of the film thickness in the site may be calculated and displayed.

Further, in this embodiment, the thin film evaluation information for each site is compared with the reference information to judge the quality of each semiconductor single crystal thin film for each site, and the thin film evaluation information for each site (specifically, the flatness and The unevenness) is output as including the determination result. By outputting the determination result of whether the flatness or the unevenness is good or bad, it is possible to grasp at a glance which site has an abnormality or the like, and it is easy to identify the cause of the abnormality or the like. As the format of this output, in the pass / fail judgment result for each site of the semiconductor single crystal thin film, the method of distinguishably outputting the site determined to be good and the site determined to be defective is the position and number of abnormal sites. And the most rational for grasping the distribution. Hereinafter, a specific example will be described.

That is, in this embodiment, by referring to the contents of the flatness determination flag Fi and the unevenness determination flag Ci in FIG. 10, it is possible to immediately identify whether there is an abnormality in the flatness or what the unevenness state is. . As for the flatness determination result, the site display color SCi has already been determined. Therefore, referring to SCi, as shown in FIG. 16, the site 225 having an abnormal flatness is set as an alarm color, and the site or the normal site is displayed in a different color or shade (or fill pattern). Also,
"∪" appears for sites that are judged to be "concave" or "convex"
Alternatively, “∩” is displayed (see FIG. 6: S127). That is, by combining and outputting the display states individually set according to the type of abnormality, it is possible to grasp at a glance what kind of abnormality has occurred. The "difference in display state" is not limited to the above-described aspect as long as it can be visually identified, and for example, character information indicating abnormality content such as "flatness abnormality",
It is possible to use various symbols, such as a symbol such as "x", which indicates an abnormality, and further, highlighting the abnormal site area with a frame line having a different thickness or color.

Further, as shown in S128 and S129 of FIG. 6, when it is desired to know more detailed information of a site, by inputting to select the site, the detailed thin film evaluation information for each site shown in FIG. 10 is obtained. It is also possible to display a list. In the present embodiment, as shown in FIG. 16, detailed information is displayed by selecting the pointer P on the screen with the mouse 206 (FIG. 1) and clicking it.

17 and 18 show examples in which the three-dimensional film thickness distribution map 210 and the site map 220 are displayed together. For example, the map 210 showing the film thickness distribution is
The film thickness distribution on the main surface of the wafer can be accurately grasped. However, when manufacturing a device such as an IC or an LSI from a wafer, information for each site is more important, and just looking at the map 210 as described above makes it possible to completely understand which site has an abnormality. Can not do it. However, when the site map 220 is displayed as in the present invention, it is possible to extremely intuitively and accurately grasp the abnormal site or the like.

The evaluation results thus obtained can be reflected in the production of silicon epitaxial wafers as follows. First, a screening step of screening a semiconductor epitaxial wafer based on the evaluation result can be performed. For example, when the number of defective sites or the formation position does not satisfy a predetermined allowable condition (for example, when the number of defective sites exceeds the specified number), the epitaxial wafer is excluded as a defective wafer. When such an inspection is performed by sampling, it is possible to exclude the entire wafer lot that has been determined to be defective. Also,
Even if the number of defective sites is within the allowable number, when the product wafer is handed over to the device manufacturer, the evaluation result as shown in FIG. It is very effective when used for

On the other hand, based on the evaluation result, it is also possible to adjust the operating conditions of the thin film growth step for manufacturing the semiconductor epitaxial wafer next. For example,
When a specific site on the wafer repeatedly shows abnormalities in flatness and unevenness, or abnormalities in film thickness, there are many cases in which the flow rate distribution of the source gas and the temperature distribution in the vapor phase growth apparatus have more than one. Therefore, the flow rate of the source gas and the distribution in the apparatus can be adjusted so that the abnormality at the specific position site is eliminated. For example, when the film thickness at the outer peripheral portion of the main surface of the wafer becomes excessive, a gas straightening plate or partition plate
The gas flow rate toward the central part of the wafer can be increased to reduce the difference in film thickness between the outer peripheral part and the central part of the wafer.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of an electrical configuration of a semiconductor epitaxial wafer measuring apparatus of the present invention.

FIG. 2 is a schematic side view showing a configuration example of a waveform measuring unit and its drive system.

FIG. 3 is a schematic plan view of FIG.

FIG. 4 is a diagram showing a concept of R-θ scanning of a waveform measurement unit and an example of setting film thickness measurement points.

FIG. 5 is a flowchart showing an example of the flow of processing in the measuring apparatus.

FIG. 6 is a flowchart showing an example of the flow of processing in the evaluation device.

FIG. 7 is a conceptual diagram showing an example of a data structure that gives a setting interval of film thickness measurement points in R-θ scanning.

FIG. 8 is a conceptual diagram showing an example of a film thickness distribution data structure obtained by R-θ scanning.

9 is a graph showing the film thickness distribution data shown in FIG.
The conceptual diagram which shows the example of the film thickness distribution data structure which performed distribution according to site.

FIG. 10 is a conceptual diagram showing a data structure example of site-specific thin film evaluation information of a site.

FIG. 11 is a schematic diagram showing a cross-sectional structure of a silicon epitaxial wafer.

FIG. 12 is a schematic diagram showing a setting example of a site.

FIG. 13 is a cross-sectional view schematically illustrating the relationship between the film thickness distribution and flatness of a silicon single crystal thin film.

FIG. 14 is a cross-sectional view illustrating various definitions of flatness.

FIG. 15 is a diagram illustrating a process of determining unevenness in a site.

FIG. 16 is a plan view showing a first display example of a site map on the evaluation device.

FIG. 17 is a surface view showing a second display example of a site map.

FIG. 18 is a plan view showing a third display example of a site map.

FIG. 19 is a diagram showing a modified example of information display in a site graphic.

FIG. 20 is a diagram showing another modification of information display in a site graphic.

FIG. 21 is a plan view showing a fourth display example of a site map on the evaluation device.

[Explanation of symbols]

100 Semiconductor epitaxial wafer measuring device WB semiconductor single crystal substrate EP semiconductor single crystal thin film SF site 211 Film thickness measurement point 150 film thickness measuring device 200 Evaluation device 209 Communication interface (means for obtaining film thickness measurement values) 220 communication line (means for obtaining film thickness measurement value) 201 CPU (site-specific thin film evaluation information creation means) 205 monitor (site thin film evaluation information output means) 210 printer (site-specific thin film evaluation information output means)

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2F069 AA47 AA54 BB15 DD15 DD25                       GG04 GG07 HH30 JJ19 NN07                       NN09                 4M106 AA01 BA08 CA48 CA70 DH03                       DH13 DJ17 DJ18 DJ20 DJ21                       DJ23 DJ32                 5F045 AB02 AF03 BB02 GB13 GB16                       GB17

Claims (20)

[Claims] 1. A method for measuring a semiconductor epitaxial wafer in which a semiconductor single crystal thin film is epitaxially grown on a main surface of a semiconductor single crystal substrate as a base surface, the method comprising: A plurality of film thickness measuring points are defined by defining a plurality of film thickness measuring points over the entire surface and measuring the film thickness of the semiconductor single crystal thin film at each film thickness measuring point, and the thin film main surface. It is divided into a plurality of sites including, and based on the film thickness measurement value of the film thickness measurement point included in the site for each site, the thin film for each site that is the evaluation information of the semiconductor single crystal thin film unique to each site A semiconductor comprising: a site-based thin film evaluation information creation process for creating evaluation information; and a site-based thin film evaluation information output process for outputting the created site-based thin film evaluation information. Pita key Shall wafer method of measurement. 2. The step of outputting thin film evaluation information for each site comprises:
The method for measuring a semiconductor epitaxial wafer according to claim 1, wherein the created site-specific thin film evaluation information is two-dimensionally output in a form corresponding to the site arrangement. 3. In the film thickness measuring step, an infrared beam is incident on the main surface of the thin film while being two-dimensionally scanned, and the film thickness is measured by an infrared absorption spectrum method at each of the film thickness measuring points. The method for measuring a semiconductor epitaxial wafer according to claim 1 or 2, wherein: 4. The semiconductor epitaxial according to claim 1, wherein the site-specific thin film evaluation information is site flatness information calculated using the film thickness measurement value. Wafer measurement method. 5. The film thickness measurement value is regarded as a distance in the normal direction of the main surface of the thin film from the base surface, and based on the coordinates of each film thickness measurement point and the corresponding film thickness measurement value. The method for measuring a semiconductor epitaxial wafer according to claim 4, wherein profile points on the main surface of the thin film are obtained, and a reference plane for calculating the site flatness is determined using the profile points. 6. The profile point is defined as four or more points for each site, the reference plane is determined as a least squares regression plane of the profile points, and the site flatness is calculated as SFQR or SFQD. The method for measuring a semiconductor epitaxial wafer according to claim 5. 7. The method for measuring a semiconductor epitaxial wafer according to claim 1, wherein the site-specific thin film evaluation information is film thickness distribution information within the site. 8. The semiconductor epitaxial wafer according to claim 1, wherein the site-specific thin film evaluation information is information on an uneven shape of the main surface of the thin film in the site. Measuring method. 9. Based on the measured film thickness, four or more profile points on the main surface of the thin film are obtained for each site, and a reference plane for each site is set based on these profile points, while at the same time within each site. Using either the profile point directly determined by the film thickness measurement value at a predetermined unevenness determination position or an estimated profile point obtained by interpolation estimation from another profile point as the unevenness determination point, the unevenness determination point is The shape of the main surface of the thin film of the site is determined to be convex when the projection is a certain distance or more from the reference surface, and the shape of the main surface of the thin film of the site is concave when the projection is a certain distance or more. 9. The method for measuring a semiconductor epitaxial wafer according to claim 8, characterized in that 10. The film thickness measuring point is set so that the peripheral portion is closer to the inner portion than the inner portion of the thin film main surface. The method for measuring a semiconductor epitaxial wafer according to. 11. The film thickness measuring step is performed by the method according to claim 2, and the two-dimensional scanning of the infrared beam is performed in an in-plane radial direction R with an origin at the center of the main surface of the thin film. 11. The method for measuring a semiconductor epitaxial wafer according to claim 1, wherein the measurement is performed by R-θ scanning in two directions including an inner circumferential direction θ. 12. The site-specific thin film evaluation information is compared with reference information to determine a site-specific quality of the semiconductor single crystal thin film, and the site-specific thin film evaluation information is output as including the determination result. The method for measuring a semiconductor epitaxial wafer according to any one of claims 1 to 11, further comprising: 13. The site determined to be good and the site determined to be defective in the pass / fail judgment result for each site of the semiconductor single crystal thin film are output so as to be distinguishable from each other. Measuring method of semiconductor epitaxial wafer. 14. A semiconductor epitaxial wafer in which a semiconductor single crystal thin film is epitaxially grown on a main surface of a semiconductor single crystal substrate, and the film thickness of the semiconductor single crystal thin film is determined as a plurality of films over the entire main surface of the thin film. A film thickness measuring step of measuring by a FT-IR method at a thickness measuring point, and dividing the main surface of the thin film into a plurality of sites each including a plurality of film thickness measuring points, and measuring the film thickness at each of the sites. A site flatness calculating step of calculating the site flatness using the value, the calculated site flatness, a site flatness output step of two-dimensionally outputting to the output device in a form corresponding to the site array, A method for measuring a semiconductor epitaxial wafer, which comprises: 15. The site-specific thin film evaluation information is created for the semiconductor epitaxial wafer to be evaluated by the method for measuring a semiconductor epitaxial wafer according to claim 1, and based on the information. A method of manufacturing a semiconductor epitaxial wafer, comprising: an evaluation step of evaluating each semiconductor epitaxial wafer; and a selection step of selecting the semiconductor epitaxial wafer based on the evaluation result. 16. A thin film growth step of epitaxially growing a semiconductor single crystal thin film on the main surface of a semiconductor single crystal substrate as a base surface, and the semiconductor epitaxial wafer according to claim 1. By the measurement method of, the thin film evaluation information for each site is created for the obtained semiconductor epitaxial wafer, and an evaluation step of evaluating each semiconductor epitaxial wafer based on the information, and based on the evaluation result, A method for producing a semiconductor epitaxial wafer, comprising: adjusting an implementation condition of the thin film growth step for producing an epitaxial wafer. 17. A semiconductor epitaxial wafer measuring device in which a semiconductor single crystal thin film is epitaxially grown on the main surface of a semiconductor single crystal substrate as a base surface, the thin film main surface of the semiconductor single crystal thin film A film thickness measuring device that determines a plurality of film thickness measuring points over the entire surface and measures the film thickness of the semiconductor single crystal thin film at each film thickness measuring point, and across the entire thin film main surface of the semiconductor single crystal thin film Film thickness measurement value acquisition means for acquiring the film thickness measurement values measured by the film thickness measurement device at a plurality of film thickness measurement points; the thin film main surface having a plurality of sites each including a plurality of film thickness measurement points. The site-specific thin film evaluation information, which is the evaluation information of the semiconductor single crystal thin film unique to each site, is created based on the film thickness measurement value of the film thickness measurement point included in the site. And a site-based thin film evaluation information output unit configured to output the created site-based thin film evaluation information, and a semiconductor epitaxial wafer evaluation apparatus. Measuring device. 18. The site-specific thin film evaluation information output means for outputting outputs the created site-specific thin film evaluation information two-dimensionally in a form corresponding to a site arrangement. A measuring device for a semiconductor epitaxial wafer according to claim 1. 19. A computer program for evaluating a semiconductor epitaxial wafer in which a semiconductor single crystal substrate is epitaxially grown on the main surface of a semiconductor single crystal substrate as a base surface, the computer program being installed in the computer. The semiconductor single crystal thin film, a film thickness measurement value acquisition means for acquiring film thickness measurement values measured at a plurality of film thickness measurement points over the entire thin film main surface, and the thin film main surface, each of a plurality of It is divided into multiple sites including the film thickness measurement points, and for each of these sites, the evaluation information of the semiconductor single crystal thin film unique to each site is based on the film thickness measurement value of the film thickness measurement points included in the site. Site-specific thin film evaluation information creating means for creating a site-specific thin film evaluation information, and site-specific thin film for outputting the created site-specific thin film evaluation information A computer program characterized by causing it to function as a semiconductor epitaxial wafer evaluation device comprising: evaluation information output means. 20. The site-based thin film evaluation information output means two-dimensionally outputs the created site-based thin film evaluation information in a form corresponding to a site arrangement. Computer program.