JP2009288016A - Fluorescent x-ray analyzer and evaluation system of semiconductor device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the performance of a semiconductor manufacturing line by performing the evaluation of the region, of which the element composition is different from that of a substrate, present in or on the substrate in a non-destructive manner with high precision in a short time. <P>SOLUTION: An evaluation target sample (substrate or the like) 4 is irradiated with X rays 3 at a low angle, for example, from the X-ray source 1 of an Mo target through a monochromator 2. The irradiation region is a region shown by a mark 3a. Further, this fluorescent X-ray analyzer has an in-plane rotary mechanism (θz) using the normal line of the surface of the substrate 4 extending from the center of the substrate 4, an angle-of-inclination altering mechanism capable of altering the incident angle (α1) of incident X rays in relation to a y-axis, and a moving mechanism capable of altering the measuring position on the surface of the substrate 4. This analyzer is especially important in that only the certain area of the substrate 4 can be irradiated with X rays and the region 3a can be altered. The evaluation is performed by measuring the intensity of fluorescent X rays emitted from the sample. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fluorescent X-ray analyzer and a non-destructive evaluation system for a semiconductor device using the same, and more particularly, a semiconductor device creation and material microfabrication using fluorescent X-ray analysis of a substrate in a semiconductor manufacturing line. The present invention relates to a technique for evaluating a thin film thickness, a doped layer, etc. widely used in the entire nanotechnology field.

  With the advancement of semiconductor technology, especially high integration and mass production technology, for example, it is important to develop technology for evaluating the area and doping amount of doped regions formed on semiconductor substrates, and the area and formation amount of thin film stacks. It has become to. As a method therefor, there is a secondary ion mass spectrometry method that utilizes a phenomenon in which a part of atoms constituting a sample becomes ions and jumps out of the sample surface when the sample is irradiated with accelerated ions. This method uses the separation of atoms from the sample surface and the generation of secondary ions generated by ion irradiation of the sample, and measures the secondary ion intensity while blowing off the atoms by ion irradiation. The element distribution measurement in the vertical direction is performed.

  In addition, a Rutherford backscattering method using a phenomenon in which ions incident on a sample are Rutherford scattered by sample atoms may be used. The Rutherford backscattering method is a principle in which ions incident on a sample with high energy are scattered by the sample, and by analyzing the energy of the scattered incident ions, the amount of elements in the sample and element distribution information in the depth direction are obtained. It is based on. Both the secondary ion mass spectrometry method and the Rutherford backscattering method are destructive analysis methods in which the sample is irradiated with ions, so that the sample is damaged by irradiation, and cannot be used for on-line evaluation in a semiconductor manufacturing line.

  In secondary ion mass spectrometry, there is a problem that the measurement value in the unbalanced region that occurs in the vicinity of the sample surface varies. In Rutherford backscattering method, the measurement of incident ions and quantitative settings of various geometries related to measurement are performed. Due to the difficulty, it is difficult to measure a nanometer-depth region with an accuracy of 1% or less. Furthermore, as the film thickness is reduced, the depth resolution required for measurement is increased, and a depth resolution of about an atomic layer (about 0.1 nm) is required. It is difficult to evaluate the film thickness with the depth resolution of the atomic layer.

  There is also a method for evaluating the thickness of the formed film formed on the surface by measuring the reflectance of X-rays incident at a low angle with respect to the substrate surface. This evaluation method utilizes the fact that X-rays reflected at the surface near the surface of the formed film or the interface with the substrate interfere with X-rays reflected at the deep interface due to the optical path difference. The film thickness is evaluated using the fact that the intensity fluctuation period with respect to the X-ray incident angle that appears when the reflectance is measured while changing the X-ray incident angle is related to the film thickness of the thin film. In this case, since the reflectance fluctuation period with respect to the incident angle becomes longer as the film thickness becomes thinner, the reflectance intensity with respect to the incident angle rapidly attenuates depending on the composition fluctuation (interface roughness) at the interface. Depending on the state, it becomes difficult to evaluate a thin film having a thickness of nm. Furthermore, in order to evaluate the film thickness, since it is necessary to perform many measurements with different incident angles, it is unsuitable for on-line inspection in a production line that requires high-precision evaluation in a short time.

  The stripping process of a thin film layer having an elemental composition different from that of the surrounding is an important process related to the creation of lines for forming wirings and patterns between devices, so that the evaluation is also very important. As for thin film stripping, a CD-SEM (Critical-Dimension Scanning Electron Microscope) method for evaluating the line width of a pattern wiring formed by stripping is widely used in semiconductor manufacturing lines. The CD-SEM method is an SEM (scanning electron microscope) apparatus specialized for the length measurement function, and analyzes the image obtained by the SEM and evaluates the line width. In this case, because of electron irradiation, it is strongly affected by the charging of the sample. The range of evaluation is limited to the field of view of the SEM. With the miniaturization of the device, the resolution of the SEM image has reached the limit required for analysis. Cannot cope with further miniaturization, such as approaching.

  FIG. 11 is a diagram showing an outline of the fluorescent X-ray analysis method described in Patent Document 1 below. In the method shown in FIG. 11, in order to evaluate the thin film 104a formed on the substrate 104, X-rays 103 are incident on the surface at a low angle. At that time, some of the incident X-rays 103 excite the elements present in the portion where the X-rays hit and emit fluorescent X-rays 107. A detector 105 for detecting the fluorescent X-ray 107 is arranged on the substrate 104, and the evaluation of the substrate (sample) 104a is performed by measuring the intensity of the fluorescent X-ray 107 emitted from the substrate (sample) 104a. It can be performed.

JP 2007-107952 A

  Meanwhile, the cost of semiconductor devices such as DRAMs and nonvolatile memories has been reduced due to miniaturization and mass production effects. In recent years, with the miniaturization of these semiconductor integrated circuits, the minimum processing dimension has reached the nm order. That is, in the semiconductor device creation process, with the miniaturization of the device size, the nm size structure is formed through many processes. Along with this, the thickness of the film deposited on the substrate surface has also decreased. Furthermore, nanotechnology technology that controls the structure of a substance in the nm region and expresses its function is also attracting attention.

  In the evaluation of regions where the elemental composition is different from the substrate existing in and on the substrate, such as thin film and doped regions, ion irradiation is used in the widely used secondary ion mass spectrometry and Rutherford backscattering methods. Therefore, it becomes destructive analysis and cannot be used for measurement online. Further, in X-ray reflectivity measurement and CD-SEM, it takes time to measure one point, and it takes time to use it for measurement over a wide range of samples. In addition, in these methods, accuracy cannot be obtained due to a theoretical limit in measurement with a size of the order of nm or less.

  When creating a nano-sized microstructure in the process of creating a semiconductor device on a semiconductor substrate, a nano-sized thin film is deposited on the semiconductor substrate to create regions with elemental compositions different from those of other regions. A device structure such as a transistor can be formed while repeating the process of processing with the determined shape of the region. At that time, the formation amount (volume / area) of a region having an elemental composition different from that of other regions, such as a doped region doped with impurities, a thin film formed in an island shape, or a laminate thereof, and the like. It is important to accurately control the amount of stripping of the region (volume and area of the recess). For that purpose, it is necessary to evaluate the formation amount, the stripping amount, the uniformity, the abnormal value, etc. without stopping the production line in a non-destructive manner.

  Further, the X-ray fluorescence method described in Patent Document 1 is widely used as an elemental analysis method in a sample, but relates to a region amount having a different element composition from the substrate existing in and on the substrate and processing thereof. It was not used for evaluation and process management.

  An object of the present invention is to improve the performance of a semiconductor manufacturing line by performing non-destructive, high-accuracy, and short-time evaluation of a region present in and on a substrate and having a different elemental composition from the substrate. With the goal.

  In the evaluation of a region present in and on a substrate and having a different elemental composition from the substrate, the present invention makes X-rays incident on the substrate, and from the elements constituting the region excited by the incident X-rays. When evaluating the region by measuring the fluorescent X-ray intensity, quantitative comparison is made by comparing the fluorescent X-ray intensity between the measurement sample and a sample with a known element concentration in the element to be measured. This area can be evaluated. Furthermore, relative intensity comparisons can be made by measurements before and after a certain process. In addition, it is possible to evaluate a wide range of measurement of a substrate with non-destructive, high sensitivity and high accuracy by mapping measurement that systematically measures at two or more measurement points.

  According to an aspect of the present invention, there is provided a method for evaluating a region provided in and / or on a substrate and having an elemental composition different from that of the substrate, the step of irradiating the sample to be evaluated with X-rays, Comparing the intensity of fluorescent X-rays from the constituent elements in the irradiated region excited by the X-rays and the fluorescent X-ray intensity from the corresponding constituent elements of the reference sample (obtained in a similar manner); Alternatively, there is provided a fluorescent X-ray analysis method comprising the steps of comparing fluorescent X-ray intensities between samples to be evaluated or in two or more identical samples. It is possible to evaluate by evaluating a region having an element composition different from that in the substrate and on the substrate.

  Thereby, it is possible to evaluate the amount of the region in which the elemental composition is different from that in the substrate and on the substrate.

  Furthermore, it is a method for evaluating a region provided in and / or on a substrate and having an elemental composition different from that of the substrate, the step of irradiating the sample to be evaluated with X-rays, and irradiation excited by the irradiated X-rays The intensity of fluorescent X-rays from the constituent elements in the region and the intensity of fluorescent X-rays from the corresponding element of the reference sample (obtained by the same method) are compared, and in the substrate and / or on the substrate And calculating a value proportional to the amount converted into the number of atoms per unit area or the amount converted into the number of atoms per unit area. Is provided. Thereby, it is possible to evaluate a region amount having a different elemental composition from the substrate existing in and on the substrate. A value proportional to the amount converted to the number of atoms per unit area broadly includes a value calculated based on the amount converted to the number of atoms per unit area, and is not necessarily limited to a proportional relationship. .

  Also, when processing is performed to remove part or all of a region provided in and / or on the substrate and having a different elemental composition from the substrate, or a substrate existing in and on another substrate is an element This is an evaluation method in the case of performing processing for adding regions having different compositions, the step of irradiating the evaluation target substrate with X-rays, and the fluorescent X-rays from the constituent elements in the regions excited by the irradiated X-rays A step of comparing the intensity with the intensity of fluorescent X-rays from the corresponding element of the reference sample (obtained by the same method), or between samples after processing or two or more samples after the same processing And a step of comparing the in-plane fluorescent X-ray intensities. Thereby, the amount of processing or processing accuracy can be evaluated.

  Also, in the substrate and / or on the substrate, when part of the region with a different element composition from the substrate is removed to form a linear region, or in another substrate and on the substrate This is an evaluation method in the case of performing a process of forming a linear region by adding a region having a different element composition from the substrate to be processed, and includes a step of irradiating the evaluation target substrate with X-rays, and the irradiated X-rays Comparing the intensity of the fluorescent X-ray from the constituent element in the region to be excited with the intensity of the fluorescent X-ray from the corresponding element of the reference sample (obtained by the same method), or And a step of comparing the X-ray fluorescence intensities in the same evaluation target sample surface between two or more evaluation target samples. Thereby, it is possible to evaluate the linear region for evaluating the linear region. The evaluation object is preferably between a large number of substrates having the same fine pattern or within a single substrate surface having the same fine pattern. Moreover, it is preferable that the incident angle of the X-rays incident on the substrate is not less than a critical angle.

  Further, the layer containing an element different from the substrate is Hf, Zr, La, Ta, Ti, Ba, Sr, Cu, Ni, Co, Ce, Dy, Pr, Y, Sr, Gd, Pt, W, Mo. , As, In, Sb, Au, and P are preferably composed of one or more elements. On the other hand, it is preferable that the substrate is composed of one or more elements of Si, Ge, Ga, As, C, In, and N, or contains glass or a polymer. In the above evaluation, the measurement may be performed at two or more locations on the substrate, and the evaluation result may be mapped. The thickness of the region having a different element composition from that in the substrate and on the substrate may be 10 nm or less. In any one of the methods described above, a thin film layer containing an element different from the substrate existing in and on the substrate may be evaluated.

  Further, the thin film layer containing an element different from the substrate present on the substrate is a multilayer film in which a plurality of layers having different compositions are laminated, and has an energy position having a peak in the evaluation of the fluorescent X-ray. Each film constituting the multilayer film can be independently evaluated based on the difference.

  In addition, when the peaks overlap with each other, by determining the center positions of a plurality of spectra to be separated according to the energy of the entire peak portion of the peak profile or the energy value acquired from the outside, the peaks are separated and the intensity analysis of each spectrum is performed. You may make it include the step to perform.

  This depends on how the word peak is interpreted, but when the peak is interpreted as the entire profile with a certain distribution, if the peak is defined as the apex of the entire profile, the spectrum to be separated by the energy of the apex is determined. Peak separation is possible by determining the center position. For the center position of the spectrum, an energy value obtained from the outside such as a database or calculation may be used.

  According to another aspect of the present invention, an evaluation target substrate is formed by exciting an X-ray source provided at a position to be irradiated with X-rays on the evaluation target substrate and an element present in the region irradiated with the X-rays. A detector that detects the fluorescent X-rays emitted from the detector, and a comparator that compares the fluorescent X-ray intensities at different irradiation positions in the substrate or between the substrates based on the fluorescent X-rays detected by the detector. There is provided a fluorescent X-ray analyzer characterized by comprising: An in-plane rotation mechanism having a normal to the substrate surface extending from the center of the evaluation target substrate as a rotation axis, an inclination angle changing mechanism capable of changing an incident angle (α1) of incident X-rays, and a measurement position on the substrate surface It is preferable to have a moving mechanism that can change the angle. In practice, the influence of the angle β is small. In addition, it is preferable to include means for evaluating the film formation amount of the multilayer film made of different elements corresponding to different energy based on the fluorescent X-ray intensities observed at different energy positions.

  A transport mechanism that transports the plurality of evaluation target substrates, the fluorescent X-ray analysis apparatus according to any one of the above provided at a position for evaluating the evaluation target substrate transported by the transport mechanism, The semiconductor device evaluation system may include an evaluation device that calculates and stores the evaluation target substrate ID or the position in the substrate and the comparison result by the detector in association with each other.

  According to the present invention, since the fluorescent X-ray intensity is measured by the detector, the detection sensitivity is high, and it is possible to increase the accuracy to 0.1% or less by securing a sufficient detection count. Any element that emits fluorescent X-rays can be measured in principle, so there is no physical limit, and measurement is possible even in a nanometer-order region or less. For this reason, it is possible to accurately evaluate a material having a fine structure, such as a semiconductor device, a nanomaterial, etc., by evaluating an amount of a region having a different element composition from the substrate existing on or on the substrate, processing thereof, and process management thereof. be able to.

  Hereinafter, an X-ray fluorescence analyzer according to an embodiment of the present invention and a semiconductor device evaluation system using the same will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration example of a fluorescent X-ray analyzer according to the present embodiment. As shown in FIG. 1, a sample (substrate or the like) 4 to be evaluated is irradiated with an X-ray 3 from a Mo target X-ray source 1 via a monochromator 2 at a low angle with the substrate surface, for example. . The X-ray irradiation area is an area having a certain area indicated by reference numeral 3a. Further, in the apparatus shown in FIG. 1, the in-plane rotation mechanism (θz) whose rotation axis is the normal line (z direction) of the substrate surface extending from the center of the substrate 4 and the incident angle (α1) of incident X-rays are changed. An inclination angle changing mechanism that can perform the movement, and a moving mechanism that can change the measurement position on the substrate surface. As a method of changing the incident angle (α1), (1) rotate by θy, (2) rotate only θx (β), (3) rotate both θy and θx (β) ( 4) There is a method of moving the incident X-ray generators 1 and 2 together.

  Here, what is particularly important is that only a certain area of the substrate 4 can be irradiated with X-rays, and this region can be changed. When incident X-rays are irradiated at a certain low angle with respect to the substrate surface, X-rays enter the surface or inside of the sample. At that time, some X-rays excite elements present in the region irradiated with the X-rays, emit fluorescent X-rays 7, and the fluorescent X-rays 7 can be detected by the detector 5. Evaluation by the fluorescent X-ray 7 is performed by measuring the intensity and energy of the fluorescent X-ray 7 emitted from the sample substrate 4. In the figure, the incident X-ray direction is shifted from the X axis by an angle β, but the angle β may be 0 degrees.

  Fig. 2 shows an example of the energy spectrum of fluorescent X-rays when a sample doped with As in the depth range of about tens of nanometers near the surface of the Si substrate was subjected to fluorescent X-ray analysis using Mo rays as incident X-rays. FIG. As shown in FIG. 2, peaks are observed at respective positions of energy of 1.74 keV, 10.53 keV, 11.73 keV, and 17 keV. From the order of lower energy, they correspond to the Si-K peak based on the Si component of the substrate, the As-Kα line, As-Kβ peak, and the Mo-Kα scattering peak, which are measurement targets. In this case, the presence / absence and concentration or area amount of an element other than Si that is an element constituting the substrate, for example, the As element, can be evaluated based on the peak intensity of As to be measured.

FIG. 3 shows the fluorescence X-ray intensity (Intensity) on the substrate surface side and the X-ray penetration depth (incident X-ray intensity on the surface when the Si substrate is irradiated with primary Mo—Kα rays having a wavelength of 0.071 nm. It is a figure which shows the inclination-angle (alpha) 1 dependence of the X-ray of (the depth used as 1 / e). As shown in FIG. 3, below the critical angle α _C , the incident beam is totally reflected, and the intensity of the fluorescent X-ray increases as the angle α 1 increases, but the X-ray does not enter so deeply. Recognize. When the critical angle α _C is exceeded, the X-rays suddenly enter the substrate deeply, and the dependency of the incident X-ray intensity on the sample depth sharply weakens. Therefore, the uniformity of the X-ray intensity near the sample surface is reduced. Rise. Therefore, it is possible to irradiate the sample to be measured with incident X-rays having high intensity uniformity without depending on the depth at which the element to be measured exists.

  FIG. 4 is a graph showing the dependence of the As Kα fluorescent X-ray count on the tilt angle of the Si substrate. Along with the As Kα fluorescence count, the target Mo count and the substrate Si count are shown. From this figure, it can be seen that the fluorescence count of As, which is the surface layer, is dominant up to the critical tilt angle, and that the Mo count and the Si count of the substrate increase when the critical angle is exceeded.

  FIG. 5 is a diagram showing a schematic configuration example of the semiconductor substrate evaluation system according to the present embodiment. As shown in FIG. 5, the components 1 to 5 of the fluorescent X-ray analyzer shown in FIG. 1 are arranged. Furthermore, an image of a manufacturing system in a semiconductor manufacturing factory is shown in which a large number of substrates 4 having the same surface structure are transported and flowed by, for example, a conveyor device B having a belt conveyor shape. Alternatively, as an image for inspecting all or a part of the sample to be evaluated by sampling, for example, all or a part of the transported sample is extracted and transferred to an apparatus as shown in FIG. 1 for measurement. There may be. That is, the form of the measurement system is not limited.

  When the substrate 4 is transported to a certain position, by the fluorescent X-ray analysis based on the above components, the surface of the substrate 4 and the region present in the substrate 4 and having a different element composition from the substrate 4 itself are evaluated. The result is configured to be analyzed by a computer CP connected to the detector 5. The computer CP can store each of the substrates in a memory in the computer CP in association with the measurement result by an ID or the like that uniquely identifies the substrate 4.

  Correspondence between the X-ray fluorescence intensity from the elements constituting the region excited by the incident X-rays and the X-rays incident on the sample 4 to be evaluated and the reference sample obtained as a reference in the same manner The region is evaluated by comparing the fluorescent X-ray intensities from the elements to be measured, or by comparing the fluorescent X-ray intensities between the substrates to be measured or in two or more identical substrates to be measured. For this reason, it is possible to cause the computer to execute an intensity comparison function by a program, for example.

  For example, as shown in FIGS. 6A and 6B, X-rays are applied to a thin film 4a having a composition different from that of the elements constituting the substrate 4 formed on the sample substrate 4 to be evaluated. The X-ray fluorescence intensity from the element constituting the region irradiated with the X-ray of the thin film 4a that is incident and excited by the incident X-ray and the amount per unit area of the element to be measured are known By comparing the fluorescent X-ray intensities from the samples of (a simple ratio or multiplying by some coefficient), the amount of the region is converted into an atomic weight (amount converted into an atomic weight per unit area). Quantitative measurement is possible.

  FIG. 7 is a diagram showing an evaluation technique based on a method different from that in FIG. As shown in FIG. 7, without using a sample whose concentration of the element to be measured is known, simply prepare a reference sample as a reference separately at a place different from the belt conveyor (the left figure in FIG. 7), The reference samples 4 and 4a may be compared with the evaluation samples 4 and 4b, 4 and 4c on the belt conveyor (comparison in the horizontal direction in the left and right diagrams in FIG. 7). Or, without preparing a reference sample, by comparing the evaluation results of the samples flowing on the belt conveyor, it is also possible to detect abnormal samples etc. on the assumption that most samples are normal. Yes (the comparison in the vertical direction in the right diagram of FIG. 7).

  Further, by comparing the relative intensities for comparing the fluorescent X-ray intensities before and after the formation of the region (surface layer 4a in the figure), the region amount corresponding to the element amount per unit area is evaluated. By performing data management or the like based on the results using a computer or the like, it is possible to evaluate a variation depending on the position of the region (X-ray irradiation region) on the substrate 4 for each substrate or on the substrate surface. At this time, paying attention to one substrate and moving the X-ray irradiation position in the xy direction and managing the evaluation result, it is also possible to evaluate the distribution of the region quantity in the plane. By this method, it is possible to evaluate fluctuations, variations, abnormal values, and the like of the concentration converted film thickness.

  Further, as shown in the upper diagram of FIG. 8, a multilayer such as a high (High) k value film (1), a metal film (2), and an impurity doped polysilicon film (3) on a substrate such as Si, for example. Even in the case where the structures are laminated, the evaluation by the fluorescent X-ray intensity can be performed in the same manner as described above. In this case, as shown in FIG. 2, since the fluorescent X-rays from the films made of different elements are observed at different energy positions, the evaluation of the respective films can be performed at a time without any destruction. As shown in the lower diagram of FIG. 8, in the case of the substrate 4 in which the gate structures GP1, GP2,... Having a certain width in the substrate are formed at a certain pitch, the gate length should be about 10 nm and the pitch should be about 100 nm. For example, a large number of gate structures GP and field regions other than the gate structure GP are formed in the region. Therefore, when a certain region (X-ray irradiation region: spot diameter) is, for example, 1 cm × 100 μm, a large number are included in the region. Since the gate structure is included, statistical processing is possible. Therefore, the gate structure can be statistically evaluated based on the intensity of the obtained fluorescent X-rays. Of course, instead of processing the deposited film on the substrate, it can be applied to the evaluation of a structure in which the substrate itself is processed to expose regions of different elemental compositions.

  In this way, when processing a region present in and / or on the substrate and having an element composition different from that of the substrate, the fluorescent X-ray intensity from the element constituting the region of the measurement target sample that has been processed And correspondence from standard samples (concentration known samples, standard unprocessed samples, standard pre-processing samples, standard post-processing samples, other standard samples, etc.) obtained by the same method The amount of processing or processing accuracy can be evaluated by comparing the fluorescent X-ray intensities from the elements to be processed, or by comparing the fluorescent X-ray intensities between processed substrates or within two or more identical processed substrates. Yes (see FIG. 9).

  That is, in the left diagram of FIG. 9, a substrate 4 that has been processed successfully is prepared, which is a substrate 4 in which a large number of fine structures are formed by processing a sample having a film deposited on the entire surface of the substrate. Is analyzed by fluorescent X-ray 7. Next, as shown in the right figure, the same X-ray fluorescence analysis is performed on the similarly processed sample substrate 4 flowing on the belt conveyor. In addition to the comparison of the evaluation results between the reference sample and the measurement target sample, the evaluation can be performed based only on the comparison results of the plurality of measurement target samples. Thereby, by comparing the fluorescent X-ray intensities, it is possible to statistically detect and evaluate fluctuations, variations, abnormal values, and the like of film components due to processing.

  Next, as shown in FIG. 10, processing for removing a part of a region having a different element composition from the substrate existing in and / or on the substrate, or a substrate existing in and on another substrate Even in the evaluation when the linear regions L1, L2, L3,... Ln are formed on the substrate 4 or in the substrate 4 by processing to add regions having different elemental compositions, the regions are extracted from the processed measurement target sample. The intensity of fluorescent X-rays 7 from the constituent elements and the reference sample obtained by the same method (concentration known sample, reference unprocessed sample, reference pre-processing sample, reference post-processing sample, Compare fluorescent X-ray intensities from the corresponding elements from test patterns, other reference samples, etc.), or compare fluorescent X-ray intensities between processed substrates or within two or more identical processed substrates By A linear region can be evaluated. At that time, by comparing the fluorescent X-ray intensity of the reference sample with the fluorescent X-ray intensity of the finely processed sample, an amount corresponding to the line width of the linearly processed sample is obtained. It is also possible to evaluate.

The intensity of the X-ray incident on the sample is gradually attenuated inside the sample, and the intensity decreases as the distance from the sample surface increases. The degree of intensity attenuation per unit depth decreases as the incident angle increases. Therefore, as the incident angle increases, the ratio of the X-ray intensity at a certain depth from the surface decreases. Therefore, the incident X-ray is irradiated uniformly on the evaluation target element in the depth direction. When the incident angle is gradually increased from 0 degree, the uniformity is rapidly improved at an incident angle equal to or greater than the critical angle. On the other hand, if the incident angle is increased, the fluorescent X-ray intensity from the substrate becomes excessively high, so that, for example, by setting the angle to 4 ° or less, higher-accuracy measurement is possible. Furthermore, by using a very small beam having an incident X-ray of 25 mm ² or less, it is possible to perform measurement including more detailed positional information such as a distribution in the substrate plane.

    In addition, the technology according to the present embodiment has a different element composition from the substrate existing in and on the substrate used when the semiconductor device structure is formed, Hf, Zr, La, Ta, Ti, Ba, Sr, Cu Ni, Co, Ce, Dy, Pr, Y, Sr, Gd, Pt, W, Mo, As, In, Sb, Au, or P, or glass, high This is suitable for evaluating a region containing one or more elements among molecules. In addition, it is highly useful for evaluation in the case where it is composed of one or more elements among the constituent elements of the substrate such as Si, Ge, Ga, As, C, In, and N. In addition, X-rays are incident on the sample, the intensity of fluorescent X-rays from the elements present in the thin film layer in the sample is measured, and a method having a thickness or width of about nm is used to evaluate the layer. Unlike other non-destructive methods, there are no physical limitations when evaluating. This is because each structure is not a measurement object, but a result of statistically processing a region including a large number of the same patterns. Therefore, other evaluation methods are non-destructive evaluations in regions where the elemental composition is different from the substrate present in and on a substrate having a thickness of 10 nm or less, where physical limitations are a problem. In particular, it has the advantage of exhibiting particularly high utility.

(Evaluation of multilayer film)
In the above embodiment, the thin film layer containing an element different from the substrate existing in and on the substrate has been described on the premise that it is a single film, but as shown in FIG. 8, it has a different composition. It may be a multilayer film in which a plurality of layers are laminated. In this case, in the evaluation of the fluorescent X-rays as described above, as shown in FIG. 2, each film constituting the multilayer film is independently determined based on the energy position having a peak with respect to the constituent elements of the film. As described above, it is also possible to evaluate the distribution of the elemental composition, the distribution of the film thickness, the distribution of the elemental composition for each different substrate, and the distribution of the film thickness within the substrate surface. In this case, since independent evaluation can be performed for each film of a multilayer film, which has conventionally been difficult to evaluate non-destructively, it is very convenient.

  In the above embodiment, the case where the present invention is applied to the manufacture of a semiconductor device has been described, but it goes without saying that the present invention can be used for sample evaluation in the manufacturing process of other electronic / optical devices such as organic EL displays. That is, in the above embodiment, the substrate is described as an example. However, the term “substrate” is not used only for the purpose of a circular thin semiconductor substrate in the field of semiconductors, but a thicker sample or the like. It can also be used for evaluation. At this time, it is suitable for evaluation on a flat surface of a sample having a flat surface.

  In the above-described embodiment, the configuration and the like illustrated in the accompanying drawings are not limited to these, and can be changed as appropriate within the scope of the effects of the present invention. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  Also, by recording a program for realizing the evaluation method / function described in the present embodiment on a computer-readable recording medium, and causing the computer system to read and execute the program recorded on the recording medium You may perform the process of each part. The “computer system” here includes an OS and hardware such as peripheral devices.

  Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.

  The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included. The program may be a program for realizing a part of the above-described functions, or may be a program that can realize the above-described functions in combination with a program already recorded in a computer system.

(Summary)
According to the present embodiment, since the fluorescent X-ray intensity is measured by the detector, the detection sensitivity is high, and it is possible to increase the accuracy to 0.1% or less by securing a sufficient detection count. In addition, since any element that emits fluorescent X-rays can be measured in principle, there is no physical limit, and measurement is possible even in a nanometer-order region or less. For this reason, it is possible to accurately evaluate a material having a fine structure, such as a semiconductor device, a nanomaterial, etc., by evaluating an amount of a region having a different element composition from the substrate existing on or on the substrate, processing thereof, and process management thereof. be able to.

  The present invention can be used for a technique for evaluating a semiconductor device in a semiconductor line.

It is a figure which shows the example of 1 structure of the fluorescent X ray analysis apparatus by this Embodiment. It is a figure which shows an example of an energy discrete X-ray spectrum using Si substrate. It is a figure which shows the inclination-angle (alpha) dependence of the X-ray of the fluorescent X ray intensity (Intensity) by the surface side at the time of irradiating the board | substrate with the primary Mo-K alpha ray of wavelength 0.071nm and the penetration depth of X ray. . It is a figure which shows the inclination-angle dependence of the Si substrate of the count number of the fluorescent X-ray of Kα of As. It is a figure which shows the example of schematic structure of the semiconductor substrate evaluation system by this Embodiment. X-rays are incident on the sample to be evaluated, and the fluorescent X-ray intensity from the elements constituting the region excited by the incident X-rays and the amount per unit area of the element to be measured are from a known sample. It is a figure which shows a mode that the said amount of area | region is quantitatively measured by atomic weight conversion amount (amount converted into atomic weight per unit area) by comparing with fluorescent X-ray intensity. FIG. 7 is a diagram showing an evaluation technique based on a method different from that in FIG. Shows how a sample with a film deposited on the entire surface of the substrate is processed to form a large number of fine structures and the substrate is successfully processed, and this is used as a reference sample and analyzed by fluorescent X-rays FIG. By removing a part of the region having an element composition different from that of the substrate existing in and / or on the substrate, or by adding a region having an element composition different from that of the substrate existing in and on another substrate. It is a figure which shows the mode of evaluation in the case of producing a linear area | region on a board | substrate or in a board | substrate. It is a figure which shows a mode that the fluorescent X-ray intensity | strength is compared and the sample processed into the linear form is evaluated. It is a figure which shows the outline of the fluorescent-X-ray-analysis method described in patent document 1.

Explanation of symbols

4 ... sample to be evaluated (substrate etc.), 1 ... X-ray source, 2 ... monochromator, 3 ... X-ray, 5 ... irradiation region.

Claims (17)

An evaluation method of a region provided in and / or on a substrate, the region having a different elemental composition from the substrate,
Irradiating the sample to be evaluated with X-rays;
Compare the intensity of fluorescent X-rays from the constituent elements in the irradiated region excited by the irradiated X-rays and the fluorescent X-ray intensity from the corresponding constituent elements of the reference sample (obtained in the same way) And a step of comparing the X-ray fluorescence intensities between the samples to be evaluated or in two or more identical samples. A method for evaluating a region provided in and / or on a substrate and having a different elemental composition from the substrate,
Irradiating the sample to be evaluated with X-rays;
The intensity of fluorescent X-rays from the constituent elements in the irradiated region excited by the irradiated X-rays, and the intensity of fluorescent X-rays from the corresponding constituent elements of the reference sample (obtained by the same method) And calculating a value proportional to the amount converted into the number of atoms per unit area, or the amount converted into the number of atoms per unit area, the amount of the region present in and / or on the substrate, A fluorescent X-ray analysis method characterized by comprising: When the processing is performed to remove part or all of the region provided in and / or on the substrate and having a different elemental composition from the substrate, or the elemental composition is different from the substrate existing in and on another substrate. It is an evaluation method when processing to add different areas,
Irradiating the target substrate with X-rays;
The intensity of the fluorescent X-rays from the constituent elements in the region excited by the irradiated X-rays, the intensity of the fluorescent X-rays from the corresponding elements of the reference sample (obtained by the same method), Or a step of comparing fluorescent X-ray intensities between samples after processing or within two or more samples after the same processing. Substrate that is provided in and / or on the substrate and is processed to remove a part of the region having a different element composition from the substrate to form a linear region, or in another substrate and on the substrate Is an evaluation method when processing to form a linear region by adding regions having different elemental compositions,
Irradiating the target substrate with X-rays;
The intensity of the fluorescent X-rays from the constituent elements in the region excited by the irradiated X-rays, the intensity of the fluorescent X-rays from the corresponding elements of the reference sample (obtained by the same method), Or a step of comparing fluorescent X-ray intensities between evaluation target samples or two or more points within the same evaluation target sample surface.   The fluorescent X-ray according to any one of claims 1 to 4, wherein the object of evaluation is between a plurality of substrates having the same fine pattern or within a single substrate surface having the same fine pattern. Analysis method.   6. The X-ray fluorescence analysis method according to claim 1, wherein an incident angle of the X-rays incident on the substrate is equal to or greater than a critical angle.   The layer containing an element different from the substrate is Hf, Zr, La, Ta, Ti, Ba, Sr, Cu, Ni, Co, Ce, Dy, Pr, Y, Sr, Gd, Pt, W, Mo, As 7. The fluorescent X-ray analysis method according to claim 1, comprising at least one element selected from the group consisting of In, Sb, Au, and P. 8.   9. The substrate according to claim 1, wherein the substrate is made of one or more elements selected from Si, Ge, Ga, As, C, In, and N, or contains glass or a polymer. The fluorescent X-ray analysis method according to claim 1.   9. The fluorescent X-ray analysis method according to claim 1, wherein measurement is performed at two or more locations on the substrate, and evaluation results are mapped.   10. The method according to any one of claims 1 to 9, wherein the thin film layer containing an element different from the substrate existing in and on the substrate is evaluated.   The fluorescent X-ray analysis method according to any one of claims 1 to 10, wherein a thickness of a region having an element composition different from that of the substrate existing in and on the substrate is 10 nm or less.   12. The method according to claim 1, wherein the thin film layer containing an element different from the substrate existing in and on the substrate is a multilayer film in which a plurality of layers having different compositions are laminated. A method for analyzing X-ray fluorescence, wherein each film constituting the multilayer film is independently evaluated based on a difference in energy position having a peak in the evaluation of the fluorescent X-ray.   In the case where the peaks overlap with each other, a step of determining the center positions of a plurality of spectra to be separated and performing an intensity analysis of each spectrum by deciding the center position of a plurality of spectra to be separated according to the energy of the entire peak portion of the peak profile or the energy value acquired from the outside The fluorescent X-ray analysis method according to claim 12, comprising: An X-ray source provided at a position to irradiate X-rays on the evaluation target substrate;
A detector for detecting fluorescent X-rays emitted from the evaluation target substrate by exciting elements present in the region irradiated with X-rays;
A fluorescent X-ray analysis apparatus comprising: a comparator for comparing fluorescent X-ray intensities at different irradiation positions within a substrate or between substrates based on the fluorescent X-rays detected by the detector.   An in-plane rotation mechanism having a normal to the substrate surface extending from the center of the evaluation target substrate as a rotation axis, an inclination angle changing mechanism capable of changing an incident angle (α1) of incident X-rays, and a measurement position on the substrate surface The fluorescent X-ray analyzer according to claim 14, further comprising: a moving mechanism that can change the angle.   16. The fluorescence according to claim 14 or 15, further comprising means for evaluating a film formation amount of a multilayer film made of different elements corresponding to different energies based on fluorescent X-ray intensities observed at different energy positions. X-ray analyzer. A transport mechanism for transporting the plurality of evaluation target substrates;
The fluorescent X-ray analyzer according to any one of claims 14 to 16, provided at a position for evaluating the evaluation target substrate transported by the transport mechanism;
An evaluation system for a semiconductor device, comprising: an evaluation device that calculates and stores a plurality of evaluation target substrate IDs or positions in the substrate and a comparison result by the detector.

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