Processing system and charged particle beam device

Abstract

A processing system and charged particle beam device are proposed to determine the growth degree or presence of defects in epitaxial layers grown within trenches or holes from images of such trenches or holes between inner spacers. A processing system equipped with a computer system is also provided, wherein the computer system calculates the distance and brightness values ​​of the layers from a signal profile obtained by irradiating layers between a plurality of structures with an electron beam, corresponding to a direction on a two-dimensional plane of the layers, and determines or outputs the state of the layers based on the distance and brightness values.

Description

Technical Field

[0001] This invention relates to a processing system and a charged particle beam device. Prior Technology

[0002] In recent years, semiconductor devices have become increasingly miniaturized, resulting in a narrowing of the epitaxial growth process window. Consequently, when closely packed epitaxial layers are arranged, inner spacers are used to prevent them from bonding together. On the other hand, charged particle beam devices such as scanning electron microscopes are used to manage the semiconductor device manufacturing process. A scanning electron microscope (SEM) is a device that obtains images or signal waveforms of a pattern by scanning a focused electron beam across a fine pattern; it is a device capable of scanning or inspecting fine patterns. However, electrons emitted from the epitaxial layer collide with the sidewalls of the inner spacer or dummy gate before reaching the sample surface, resulting in low detection efficiency and making it difficult to perform high-precision measurements of the epitaxial layer.

[0003] Patent Document 1 discloses a scanning electron microscope for improving pattern images to examine defects in the underlying layer. More specifically, it discloses a method that utilizes the difference in the penetration length of electrons into the sample caused by the accelerating voltage, uses two types of accelerating voltages to acquire images separately, and takes the difference between them to highlight the underlying pattern. [Previous Technical Documents] [Patent Literature]

[0004] [Patent Document 1] U.S. Patent Application Publication No. 2010 / 0136717 Summary of the Invention

[0005] [The problem the invention aims to solve]

[0006] If the accelerating voltage is changed, the detection efficiency will differ, thus affecting not only the epitaxial layer of the trench between inner spacers but also the generated SEM image itself. Furthermore, even if electrons reach the epitaxial layer, the secondary electrons colliding with the sidewalls will still reduce detection efficiency. As disclosed in Patent Document 1, even with a change in the accelerating voltage and subsequent imaging, it is still impossible to focus solely on the epitaxial layer of the trench between inner spacers, making high-precision measurement difficult.

[0007] On the other hand, in recent semiconductor devices, to increase the on-current of transistors, materials with different lattice constants, such as SiGe, are epitaxially grown from Si, thereby improving mobility through slight crystal distortion. If the epitaxial layer is too thin, the resistance between the source and drain is too high, resulting in insufficient transistor on-current. If it is too thick, it increases contact with the insulating material or high-k dielectric film, thus increasing electrostatic capacitance and reducing transistor response performance. Therefore, proper growth management of the epitaxial layer is necessary. Furthermore, due to the difference between N-type and P-type epitaxial growth, the distances between inner insulating materials and within the wafer plane will also differ, requiring observation and measurement.

[0008] Ideally, electron microscopes capable of measuring or inspecting fine patterns should be used in measurement. However, the amount of secondary electrons detected in epitaxial layers is lower than in other areas such as inner insulating materials, making observation of epitaxial layers very difficult. Furthermore, in recent years, semiconductor process management has seen a high demand for efficiency in measurement or inspection, emphasizing automation.

[0009] This invention was created to solve such a problem. The present invention provides a processing system and a charged particle beam device, which aims to determine the growth degree or presence of defects of the epitaxial layer grown in the groove or hole from the image of such groove or hole between the inner spacer. [Technical means to solve the problem]

[0010] An example of the processing system of the present invention, It is a computer system processing system, among which, The aforementioned computer system, By irradiating layers between a plurality of structures with an electron beam, a signal profile corresponding to a direction on a two-dimensional plane of the aforementioned layers is obtained. From this signal profile, the distance and brightness values ​​of the aforementioned layers are calculated. Based on the aforementioned distance and brightness value, the state of the aforementioned layer is determined or output.

[0011] One example of the charged particle beam device of the present invention includes the above-described processing system. [Effects of the Invention]

[0012] Based on the above structure, the growth degree of the epitaxial layer growing in the groove or hole can be measured or the presence or absence of defects can be determined from the image of the groove or hole between the inner spacer. Simple Explanation of the Diagram

[0013] [Figure 1] A schematic diagram of the entire scanning electron microscope of Embodiment 1 disclosed herein. [Figure 2] The process of registering the recipe in Example 1. [Figure 3] Relationship between cross-sectional view, top view and outline of epitaxial growth in Example 1. [Figure 4] An example of the GUI used to determine the threshold in Example 1. [Figure 5] The process of formula execution in Example 1. [Figure 6] An example of measuring the width of the epitaxial section in Example 1 when there is brightness below the threshold. [Figure 7] An example of measuring the distance between inner insulating materials in Example 1 when there is no brightness below the threshold. [Figure 8] An example of a GUI used to determine a threshold in Embodiment 2 of this disclosure. [Figure 9] An example of a GUI used to determine a threshold in Embodiment 3 of this disclosure. [Figure 10] The process of formula execution in Example 3. [Figure 11] Example of Example 4 with no internal isolation material or weak signal. Implementation

[0014] The following describes embodiments of this disclosure based on the accompanying drawings. [Example 1] Figure 1 is a schematic diagram of the entire scanning electron microscope (charged particle beam device) of Embodiment 1 disclosed herein. The device structure in Figure 1 is explained. Downstream of the electron beam 102 drawn from the electron source 101, a deformable illumination aperture 103, a detector 104, a scanning deflector 105, and an object lens 106 are arranged. Furthermore, the electron optical system also includes a calibrator for adjusting the central axis (optical axis) of the primary beam, an aberration corrector, etc. (not shown).

[0015] Additionally, the objective lens 106 in this embodiment is an example of an electromagnetic lens that controls focusing by excitation current, but it can also be an electrostatic lens or a combination of an electromagnetic lens and an electrostatic lens. The platform 107 is configured to support and move the wafer, i.e., the sample 108.

[0016] The electronic source 101, detector 104, deflector 105 for scanning, object lens 106, and platform 107 are all connected to the control device 109, and a system control unit 110 is connected to the control device 109.

[0017] The system control unit 110 is equipped with a computer system and functions as the processing system in this embodiment. The operation of the system control unit 110 is realized by this computer system. The computer system of the system control unit 110 is functionally equipped with a memory device 111, a calculation unit 112, and connected to an input / output unit 113 equipped with an image display device.

[0018] Although not illustrated, the components of the system control unit 110, excluding the control system and circuit system, are housed within a vacuum container and operate by vacuum degassing. Furthermore, it includes a wafer transport system for placing wafers onto the platform from outside the vacuum.

[0019] Furthermore, the system control unit 110 is more specifically configured to include a calculation unit 112, i.e., a central processing unit, and a memory device 111, i.e., a memory unit. This central processing unit, acting as the aforementioned calculation unit 112, executes programs stored in the memory device 111, thereby enabling image processing related to defect inspection or dimensional measurement, or control of the control device 109, etc.

[0020] In this specification, the system control unit 110, input / output unit 113, control device 109, etc., are sometimes collectively referred to as the control unit. Furthermore, the input / output unit 113 can be designed as an input means such as a keyboard or mouse and a display means such as a liquid crystal display device, respectively, serving as an input unit and an output unit. Alternatively, it can be configured using an integrated input / output means such as a touch panel.

[0021] This describes the image observation performed using the relevant apparatus. The electron beam 102 emitted from the electron source 101 is focused by the objective lens 106, achieving a minimum beam diameter on the sample 108. The scanning direction is controlled by a deflector 105, which is controlled by a control device 109, causing the electron beam 102 to scan a predetermined area of ​​the sample 108.

[0022] The electron beam 102, reaching the surface of the sample 108, interacts with the material near the surface. This generates secondary electrons, such as backscattered electrons, secondary electrons, and Auger electrons, from the sample, which become the desired signal. This embodiment illustrates the case where the signal is a secondary electron.

[0023] Secondary electrons 114 generated when the electron beam 102 reaches the sample 108 are detected by detector 104. The signal processing of the secondary electrons 114 detected by detector 104 is performed synchronously with the scanning signal sent from control device 109 to scanning deflector 105, thereby forming a SEM image for observation of sample 108. In this embodiment, detector 104 is positioned upstream of comparison lens 106 or scanning deflector 105, but the order of placement can be interchanged.

[0024] This embodiment illustrates the use of brightness profile recipe registration and execution. Figure 2 shows the recipe registration process, Figure 3 shows the relationship between the cross-sectional view and top view of the epitaxial growth and the profile, and Figure 4 shows an example of a GUI (Graphical User Interface) used to determine the threshold.

[0025] The processing in Figure 2 is controlled by the system control unit 110. In Figure 2, firstly, in order to compare the brightness values, the mechanical error and time-dependent changes of the detector are corrected (201). For example, the correction can be made by obtaining the characteristic curve of the brightness amplification caused by applying voltage to the detector, or by compensating for the brightness of the same pattern.

[0026] Next, the pattern of the test object, i.e., sample 108, is photographed, and the detector parameters (202) at the time of photographing are memorized. Brightness correction compensation can also be applied to the photographed image.

[0027] In regions where epitaxial growth is insufficient, the brightness will be dimmer compared to regions outside the epitaxial portion (e.g., the inner spacer) or to regions where the epitaxial portion is fully grown. This is illustrated in Figure 3.

[0028] Figure 3(a) is a cross-sectional view of the case where epitaxial growth is sufficient, and Figure 3(b) is a cross-sectional view of the case where epitaxial growth is insufficient. On the substrate 303, the epitaxial portion 302 (epithelial growth layer) is grown between two inner spacers 301, but the growth degree of the epitaxial portion 302 in Figure 3(b) is smaller than that in Figure 3(a).

[0029] Figure 3(c) is a top view of the case where epitaxial growth is sufficient, corresponding to Figure 3(a). Figure 3(d) is a top view of the case where epitaxial growth is insufficient, corresponding to Figure 3(b). The arrows indicate the scanning direction of the charged particle beam, i.e., the time axis direction of the signal profile. This direction is a direction on the two-dimensional plane of the epitaxial growth layer, and the signal profile is generated according to this direction. The brightness of the regions at both ends of the epitaxial portion 302 is smaller in Figure 3(d) than in Figure 3(c).

[0030] Figure 3(e) shows the image outline (signal outline) when the epitaxial growth is sufficient, and Figure 3(f) shows the image outline (signal outline) when the epitaxial growth is insufficient.

[0031] Furthermore, the internal insulating material (structure) can be made into, for example, a semiconductor fin-type gate layer. In this way, appropriate processing can be performed in a semiconductor device with a specific structure.

[0032] In Figure 2, after step 202, a threshold (e.g., % unit) for determining the growth degree of the epitaxial layer is input and memorized as a formula parameter (203).

[0033] For example, in the epitaxial layer, or between two inner spacers, if the brightness of a certain area is less than 30% of the maximum brightness of the epitaxial layer, the epitaxial growth in that area is defined as insufficient. This value "30%" is recorded as information in the formulation. Alternatively, the brightness value itself, "3000", can be set as the threshold.

[0034] For example, in the GUI shown in Figure 4, the user determines the threshold and inputs it into, for example, the threshold input field 401. In this example, it is 30%. The system control unit 110 receives and remembers this threshold.

[0035] Figure 5 illustrates the process of formula execution. The processing in Figure 5 is controlled by the system control unit 110. First, as with formula registration, in order to compare the brightness values, the mechanical error of the detector and the change over time are corrected (501).

[0036] Subsequently, an image is captured (502). Brightness correction compensation may also be applied to the captured image.

[0037] Next, the region between inner insulating materials is identified (503). In this specification, "between inner insulating materials" means between two inner insulating materials. As a specific example, based on the signal profile, a plurality of first positions of the regions of a plurality of structures (two inner insulating materials in this embodiment) are identified, and the region between these first positions is identified.

[0038] Figures 6 and 7 illustrate an example of this process. Figure 6 shows an example of the outline of an image in the case of insufficient epitaxial growth, and Figure 7 shows an example of the outline of an image in the case of insufficient epitaxial growth.

[0039] Figures 6(a) and 7(b) illustrate the respective signal profiles, with thresholds 601 and 701 representing the thresholds registered in the formulation (input to, for example, the GUI in Figure 4). Figures 6(b) and 7(b) illustrate examples of inner insulating material positions 602 (first position) and 702 (first position).

[0040] The location of the inner insulating material is identified, for example, as the peak location of the signal profile, but other identification methods can also be used. More specifically, it can also be detected by binary value or the zero-point intersection of the first derivative of the profile, the peak of the second derivative, or other methods.

[0041] In Figure 5, next, the brightness (504) below the threshold remembered during formula registration is searched from the center of the inner spacer between inner spacers toward the left and right (or both sides) inner spacers. For example, based on the above plurality of first positions, the second position of the epitaxial growth layer is identified. As a specific example, the second position is identified as the central position between two first positions, namely the central position 603 and the central position 703 between inner spacers. As another specific example, the second position is identified as the peak position between inner spacers.

[0042] Then, based on this central position and the threshold registered in the formula, the system searches for brightness below the threshold towards the left and right inner insulating materials, thereby identifying multiple edge positions (third positions) of the epitaxial growth layer. For example, as shown in Figures 6(b) and 7(b), the system control unit 110 searches from the central position 603 and the central position 703 towards both sides of the signal profile, thereby identifying multiple edge positions. In this way, edge positions can be identified on both sides of the central position.

[0043] Next, the system control unit 110 identifies the edge position (505). When there is a brightness below the threshold, as shown in FIG6(c), the position of that brightness (more specifically, the position of the brightness below the threshold first found in each search direction) is designated as the edge position 604 (third position) of the epitaxial section. On the other hand, when there is no brightness below the threshold, as shown in FIG7(c), the end of the inner spacer is designated as the edge position 704 (third position). The end of the inner spacer is identified as a point where, for example, the brightness is minimal between inner spacers.

[0044] Here, although this embodiment searches for brightness "below the threshold," it can also search for brightness "below the threshold." That is, when the brightness values ​​between the two inner spacers are all above the threshold, or when the brightness values ​​between the two inner spacers exceed the threshold, the system control unit 110 calculates the distance of the epitaxial growth layer based on the positions of the inner spacers on both sides, rather than the edge positions. In this way, the distance can be calculated by appropriately classifying the cases according to the brightness.

[0045] As another variation, it is also possible to determine whether the brightness value between the two inner insulating materials is above (or exceeds) the threshold, rather than determining the "entire" brightness value between the two inner insulating materials.

[0046] After detecting the edges on both sides (left and right) in this way, the distance between the epitaxial growth layers (506) is calculated based on the edge positions. For example, the distance between two edge positions is calculated. As a specific example, the distance is calculated to be 605 in the example of Figure 6(c) and 705 in the example of Figure 7(c).

[0047] In this manner, the system control unit 110 obtains a signal profile corresponding to a specified direction by irradiating the epitaxial growth layer between the two inner insulating materials with an electron beam, thereby calculating the distance and brightness value of the epitaxial growth layer.

[0048] Then, the measured distance (507) is output. When there is a brightness below the threshold, as shown in Figure 6(c), the distance between the edges is output as the width of the epitaxial portion. On the other hand, when there is no brightness below the threshold, as shown in Figure 7(c), the distance between the edges is output as the distance between the inner insulating materials.

[0049] Therefore, the state of the epitaxial growth layer is determined or output based on the distance and brightness value of the epitaxial growth layer. For example, the distance between edges can be output as a value indicating the growth degree of the epitaxial growth layer. In addition, when there is no brightness below the threshold (Figure 7), information indicating that the epitaxial growth layer has no defects can be output, and when there is brightness below the threshold (Figure 6), information indicating that the epitaxial growth layer has defects can be output.

[0050] In this way, according to the scanning electron microscope and system control unit 110 of Embodiment 1, the growth degree of the epitaxial layer grown in the groove or hole between the inner spacer material can be measured or the presence or absence of defects can be determined from the image of the groove or hole between the inner spacer material.

[0051] In particular, as shown in Figures 6 and 7, the determination is made based on the inner insulating material position 602 (first position) and the inner insulating material position 702 (first position), the central position 603 (second position) and the central position 703 (second position), the edge position 604 (third position) and the edge position 704 (third position), so it can be processed based on clear position identification.

[0052] [Example 2] This embodiment illustrates an example of recipe registration based on setting thresholds for each element. Hereinafter, descriptions of parts common to Embodiment 1 will sometimes be omitted.

[0053] Figure 8 illustrates an example of a GUI used to register different thresholds for P-type and N-type elements. In GUI 801, the threshold is set to 20% for P-type elements, and in GUI 802, the threshold is set to 30% for N-type elements.

[0054] The system control unit 110 pre-memorizes these two types of thresholds, obtains information indicating whether the element being measured is P-type or N-type, and selects a threshold for use based on this information. In this way, the system control unit 110 memorizes multiple thresholds and selects a threshold according to the type of layer. Information indicating the type of layer (e.g., information indicating whether the element is P-type or N-type) can be input from, for example, a GUI (not shown), but can also be automatically obtained by the system control unit 110.

[0055] Furthermore, although different thresholds are used for P-type and N-type components in this embodiment, other criteria can also be used to classify the types of components.

[0056] In this way, by setting thresholds for each type of component, it is possible to measure the growth rate or assess the presence or absence of defects by using appropriate thresholds according to the type of component.

[0057] [Example 3] This embodiment describes the recipe registration and execution when determining the brightness based on the area below a threshold. Hereinafter, descriptions of parts common to Embodiments 1 or 2 will sometimes be omitted.

[0058] Figure 2 (above) illustrates the recipe registration process, and Figure 9 illustrates the GUI used to determine the threshold from the histogram. Steps 201 and 202 can be designed as in Example 1. In step 203, the user confirms the maximum brightness (or actual maximum brightness) of the epitaxial layer from the histogram and inputs a value lower than that as the threshold. For example, 3000 is input when the maximum brightness is 10000. Alternatively, the threshold can be set as a ratio relative to the maximum brightness value. In the example of Figure 9, 3000 LSB (Least Significant Bit) is input as the threshold.

[0059] Figure 10 illustrates the flow of formula execution in this embodiment. Steps 1001 to 1003 can be designed as steps 501 to 503 in Figure 5.

[0060] After step 1003, the brightness below the threshold is detected in the region between the inner and inner spacers, and its area is output (1004). This area represents the growth degree of the epitaxial growth layer (however, the larger the value, the lower the growth degree). Alternatively, the growth degree can be output as the proportion of the area of ​​brightness below the threshold relative to the entire area. Also, the growth degree can be output as the area of ​​brightness above the threshold within the region (in this case, the larger the value, the higher the growth degree), or the growth degree can be output as the proportion of the area of ​​brightness above the threshold relative to the entire area.

[0061] Furthermore, at the time point of formula registration (e.g., in the processing shown in Figure 2), a threshold or a threshold for the area or proportion that is determined to be insufficient epitaxial growth (i.e. defective) can also be registered, and the degree of epitaxial growth or the presence or absence of defects can be determined and output based on these thresholds.

[0062] In this embodiment, the system control unit 110 determines or outputs the state of the epitaxial layer based on the area of ​​the epitaxial layer (in this embodiment, the layer identified by the distance between inner spacers) having a predetermined brightness range. In this way, for example, a determination with strong noise resistance can be made.

[0063] [Example 4] Figure 7 shows an example where the signal from the inner insulating material is clear. However, in cases like Figure 11 where there is no inner insulating material or the signal from the inner insulating material is unclear (1101), the waveform profile will look like 1102. In this case, the distance 1105 between the left and right epitaxial growth sections to be measured and the position 1104 where the signal is at its minimum can be set, or it can be designed to return a pre-determined value. That is, the system control unit 110 can calculate the distance of the epitaxial growth layer based on the position where the signal is at its minimum in the signal profile, or it can be calculated using a pre-memorized value. In this way, the distance can still be output even when there is no inner insulating material or the signal from the inner insulating material is unclear.

[0064] [Other Embodiments] In the above embodiments, the layer to be determined as the epitaxial growth layer is, in particular, the state of the layer includes the degree of growth of the layer (represented, for example, by numerical values) and / or the presence or absence of defects (represented, for example, by binary value information). In this way, appropriate determination can be made specifically for the epitaxial growth layer. However, other types of layers can also be designated as the object, in which case the method for determining and representing the state of the layer can be appropriately designed by those skilled in the art.

[0065] 101: Electronic Source 102: Electron Beam 103: Deformation Illumination Aperture 104: Detector 105: Deflector for Scanning Bias 106: Objective lens 107: Platform 108: Sample 109: Control device 110: System Control Department (Processing System) 111: Memory device 112: Calculation Department 113: Input / Output Section 114: Secondary Electrons 301: Internal insulation material (structure) 302: Epitaxial Layer 601: Threshold 602: Location of inner insulating material (position 1) 603: Central position (2nd position) 604: Edge position (3rd position) 605: Distance 701: Threshold 702: Location of inner insulating material (position 1) 703: Central position (2nd position) 704: Edge position (3rd position) 705: Distance 1101: Situation where there is no inner insulating material or the signal of the inner insulating material is unclear. 1102: Contour Waveform 1104: Become the smallest position 1105: Distance

Claims

1. A processing system, which is a processing system equipped with a computer system, wherein, The aforementioned computer system identifies a plurality of first positions of regions of the plurality of structures by irradiating layers between plurality of structures with an electron beam, corresponding to a direction on a two-dimensional plane of the aforementioned layers. Based on the plurality of first positions, it identifies second positions of the aforementioned layers. Based on a predetermined threshold and the aforementioned second positions, it identifies a plurality of third positions of the aforementioned layers. Based on the plurality of third positions, it calculates the distance and brightness values ​​of the aforementioned layers. The aforementioned second position is the central position between two first positions. The plurality of third positions are identified by searching from the aforementioned central position toward both sides of the aforementioned signal profile. The aforementioned layers are epitaxial growth layers. Based on the area of ​​the aforementioned layers with a predetermined brightness range, it determines or outputs the growth degree or the presence or absence of defects in the aforementioned layers.

2. The processing system as described in request item 1, wherein, The aforementioned structure is an inner spacer.

3. The processing system as described in request item 1, wherein, The aforementioned computer system calculates the aforementioned distance based on the aforementioned plurality of first positions rather than the aforementioned plurality of third positions when the aforementioned brightness value between the aforementioned plurality of first positions is above the aforementioned threshold, or when the aforementioned brightness value between the aforementioned plurality of first positions exceeds the aforementioned threshold.

4. The processing system as described in request item 1, wherein, The aforementioned processing system stores multiple of the aforementioned thresholds and selects the aforementioned threshold according to the type of the aforementioned layer.

5. The processing system as described in request item 1, wherein, The aforementioned computer system calculates the aforementioned distance of the aforementioned layer based on the location where the signal becomes the minimum value in the aforementioned signal profile.

6. A charged particle beam device comprising a processing system as described in claim 1.

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