TW552464B - A method of measuring parameters relating to a lithography device - Google Patents

Abstract

The present invention provides methods for determination of parameters in lithographic devices and applications by diffraction signature difference analysis, including determination of center of focus in lithography devices and applications, such as for photoresist lithographic wafer processing.

Description

M2464, Description of the invention (l) Cross reference sign analysis of too relevant applications to determine the center of the moon 6 pounds =, name J "Using diffraction special U.S. patent application method, method and device" 60 / 230, 49 No. 1 is hereby incorporated by reference; this case has its advantages: the patent description of this case part of the scope of moxibustion (technical scope) Fang i: ί: 1 ί radiographic analysis to determine the parameters of lithography applications Center of focus. & Engraving the application of the example of photoresistance lithography wafer processing technology background: the author's several publications and year of publication, and because of the recent publication of π ;: White use skills 〇 于 太 女 识 # 松 ，. Γϋ Solution background, X π & δχ and other publications are intended to suffice the second evidence to explain that these publications are allowed to be determined as ancient patent Custom skills. ~ Lithography in semiconductor, optics and related products Lithography is used to make Fengyao &U; various useful applications. Lei Lu uses Wanzheng Γ + conductor device ', for example, to generate light on a wafer to modulate the light and reverse the display device, disk head, etc. One application is through lithography: photolithography to transmit the pattern of a photomask or plate to a substrate on the substrate or develop a tincture layer, and the exposed pattern is etched away (positive. However, in addition to photoresist, it is more resistive. The 3D image pattern formed by the agent layer is particularly useful in the semiconductor industry in photolithography, especially in the form of light t ®, and is used in the semiconductor industry.

The quasi eight sons = two, machine, the stepper usually includes a miniature lens and a lighting lamp ^ wafer flat light plate platform, crystal and operation methods, also κ κ into the machine device can use positive and negative photoresistors Agent two or both. ', ° Using the original step-repeat format or step-scan format, the average energy of the image pattern developed by the exposure and focus determines the layer, and it is the image, the focus determines the position of the focal plane of the shadow system to be developed, such as Mining quality. The exposure is determined by reducing the lighting time and intensity. Focus system to set. Use photoresist lithography to set the image per unit area of the resist. Relative to clarity

By changing the thickness of the resist layer, the topography of the substrate, and the focus offset of the stepper (Coyus dnft), the exposure and focus can be changed locally. Because exposure and focus can vary, image patterns generated by lithography need to be monitored to determine if they are within acceptable tolerances. Focus and exposure systems are especially important when sub-micron lines are produced by photolithography.

Various methods and devices have been used to determine the focus of steppers and similar lithographic devices. Scanning electron microscopes (SEMs) and similar devices are used. However, although the SEM method can resolve details of about 0.1 μm, the process is expensive ′ requires a high vacuum chamber, the operation is relatively slow, and it is difficult to automate. Optical microscopy can also use 'but does not have the resolution required for sub-micron structures. Other methods include the development of special targets and test masks, such as U.S. Nos. 5,712,707 '' 5,953,123 and 6,088,113, disclosed by patents. It is also known that there are some overlay error methods, for example

552464 V. Description of the invention (3) As disclosed in US Patent No. 5,952, 1 32, the resolution is increased due to the nature of the target. However, although some methods are mirrors or similar direct measurement devices. Still using SEM, optical microscopy :: Some people use various scatterometers and related devices and measurement methods to produce electron and optoelectronic semiconductor materials, electro-optical components, and lateral dimensions in the dozens & Tian Mo r pi from Gan ~ uu The characteristics of the microstructure of the siege material, which is less than ten micrometers and less than one tenth of a micrometer. For example, Accent 〇 Pt ^ cal technology company made and sold, and in the United States No. 5,703,692 = its: part of the CDS200 scatterometer, which is a fully automated non-breaking ^ = boundary size (⑻ Measurement and profile analysis system. This device can analyze critical dimensions below 丨 nanometers, determine the profile of the profile and perform layer thickness estimation at the same time. It is expected to be a single diffraction stage as a function of the illumination angle of the illumination beam. This device can also monitor its intensity. This method can also be used to monitor the Oth or specular level of the sample and the intensity change of higher diffraction levels, and this provides useful information in determining the nature of the target of the illuminated sample ' Information can also be used as an indirect monitor of the process. Many methods and devices for scatterometer analysis have been taught, including U.S. Nos. 4,71〇, 642, 5,164,790 'and 5,241,369. 'Those contained in patents 5,703,692, 5,867,276, 5,889,593, 5,912,741 and 6,10,9 8 5. The scatterometer and related devices can use a variety of different methods of operation. One of them Method is to use one A known single-wavelength source, and the incident angle ㊀ varies within a predetermined continuous range. Another method is to use several laser beam sources and optionally maintain a different incident angle ㊀. There is also a method Yes

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552464 V. Description of the invention (4) The use of a light incident detector and the use of a light detector also knows that a wide incidence angle detector #, which produces a relative shot of any target within the enclosure Φ, is used to detect various vibration changes and adjustments. The light source has a diffraction spectrum light source, and Θ is selectively obtained by using a filter to obtain a light source or other radiation or a combination or characteristic thereof by using a variable polarization of the optical device. Where the incident ground is kept solid to produce a certain phase and filter light source. Other radiation sources change the purpose, that is, the light system is illuminated from a certain wavelength range. In addition, various incident phase ranges are known, and a variable phase optical module is used. In addition, the incident angle of the light from S to P module can also be rotated around the target area or the target area by a range of sources. Using these devices can and is known to get something

In addition to the scatterometer device, there are other devices and methods that can use an optical light source that can be reflected or transmitted by a diffraction grating, and capture the light with a detector to determine the 0th level or Diffraction characteristics of higher diffraction levels. In addition to scatterometers, these other devices and methods include ellipsometry and reflectometers. It is also known that non-optical diffraction characteristics can also be obtained if other radiation sources are used, such as X-rays.

Various sample targets are known in the art. A simple and commonly used target is a diffraction grating, which is essentially a series of periodic lenses with a typical width-to-space ratio between about 1 ·· 1 and 1: 3, but other ratios are known. A typical diffraction grating, for example, 1 ·· 3, has a line width of 100 nm and a space of 300 nm. The total pitch (width plus space) is 400 nm. Width and pitch are a function of the resolution of the lithographic process. Therefore, when the lithography process allows for smaller widths and spacings, ‘far widths and spacings can also be reduced ^ Diffraction techniques can be used for any feasible widths and spacings, including smaller than those commonly used today.

Page 7 552464 V. Description of Invention (5) Many of those. Diffraction gratings are usually based on a known (dry Λ grain Λ wide range) technique known on the single-wafer: multiple maps, such as using different focus settings or different exposures. Another: also know if Obtained from diffraction gratings of various focal points; = = Compared with a theoretical model that generates chirped information: = Gongxun library, the scattering and diffraction gratings can be used to determine. With the actual diffraction metric Let's compare the model $, according to :, Jiao E? The value of ⑶ obtained, and make the result with a throw: Qu = already. However, w method requires considerable time and computer resources, private property theory model. Brief Description of the Invention of the Invention The invention provides a method for measuring various parameters of a lithographic apparatus, which includes the following steps: providing a substrate with a plurality of diffraction gratings formed by a lithographic process on the substrate; Iso-diffraction includes several separated elements; using a radiation source tool to measure diffraction characteristics for at least three of the gratings; and determining the differences between such diffractions to determine the intended parameters of the lithographic apparatus. Here Method 1 board can be wrapped One wafer. This method may further include using a lithographic apparatus to form a plurality of diffraction gratings with known different focus settings, and determine two adjacent diffraction settings of a diffraction grating, wherein the two diffraction gratings are between The diffraction feature difference is lower than the diffraction feature difference between the other two adjacently set burn-in gratings, so the parameter is

552464

5. Description of the invention (6) Focus center of the lithographic apparatus.

In a preferred embodiment, the known different focus settings are equal increments = different focus settings. Alternatively, the known different focus settings are different focus settings, and the method further includes using a mathematical algorithm to normalize different focus settings of unequal increments. The scale method further includes plotting the difference in diffraction characteristics, in which the 4-inch eigen-differential difference between the diffraction gratings is approximately a value increment of a parabolic curve with a slope of zero at the center of the focus. The dream of determining the difference in diffraction characteristics between diffraction gratings involves reading the difference using a degree of chirp. Available Metrics

It is a kind of data analysis method of root mean square error. The step of determining the minimum difference may additionally include a comparison of the weighted average of the diffraction characteristic differences between the 70, 70, and 70 thumbs. In one embodiment of the method, the method further includes using a light beam device with the same focus setting to form a plurality of diffraction gratings, and translating the difference between them for use as a position of the diffraction gratings on the substrate. function. In another example of this method, it also includes forming several diffraction gratings with known different focus settings and known different agent settings, and determining the effect of the dose on the focus. The plurality of diffraction gratings may include several identical groups of diffraction gratings known to have a non-focus setting, which groups are changed using different known dose settings. The present invention further provides a method for determining a focus center of a lithographic apparatus, which includes the following steps: providing a substrate, the substrate is provided with a plurality of diffraction gratings made by photolithography; Includes a number of different known focus settings; uses a radiation source tool to determine diffraction characteristics for at least three of several diffraction gratings; measures the diffraction of adjacent focus settings

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The diffraction characteristics of the gratings are different from each other; and the smallest difference between the diffraction gratings of the diffraction gratings which are the focus setting centers is determined. The features in the focus have an increase in the similarity value between them. In the example of a pairwise phase weighting average, the grid will 'cause the source-type source tool obtained in the implementation of beam focusing to include a long-range knowledge. 4 In one embodiment of the method with a phase, the phase difference characteristic is a minimum difference amount. The step of ascertaining the adjacent focus setting may include analyzing the comparison of the diffraction grating values of the adjacent focus setting using the data of the root mean square error, and the step of determining the most certain minimum difference includes obtaining the smallest diffraction feature from each other. The difference includes the parabolic curve. In the foregoing method, in the example of the radiation source, the light source-type tool includes a measurement angle obtained by scanning a range of incident angles, and the obtained instrument may further include a sub-angle scatterer including a plurality of laser beam sources. Nine-spectrum incident light source, an optical system for illumination, and a detection of its diffraction characteristics include an incident light source, a number of stages, a parabolic winding with a diffraction slope set to zero for the focus and adjacent focus of the beam A measure of the distance between the gratings, including the Daniel method, to determine the small difference between them. For the difference of the minimum tool, the near diffraction characteristics of the curves of the gratings are not limited to the method that also includes the difference. This difference in diffraction characteristics is added in another implementation of this method. Diffraction light set at the adjacent focus is applied to a parabolic curve value. It includes a light source type, an incident laser beam source, a concealed optical system, and a diffraction scheme for its diffraction characteristics. Implement the light in a different implementation in another. In a method for correcting an embodiment, focusing and measuring an obtained result, another embodiment changes an S and P polarization incident phase range tool. The laser and the detector are used. In the light example, the light source is used to detect the incident wave length.

552464 V. Description of the invention (8) An optical system. At all front fixed angles, a source-type tool is a step-by-step tool that operates with a source of diffraction features to perform a transmission-wound mirror level. The diffraction light of the point of the present invention sets a lithographic device. Diffraction features, methods of the present invention, including but not reflective or transmissive or variable setting with a lithographic apparatus' and a known method for detecting the phase of the obtained diffraction features The step of measuring the diffraction characteristics includes performing a phase measurement using a wide-spectrum radiation operating at a variable angle Θ or a variable angle φ. In these methods, the measurement of diffraction includes phase measurement using a fixed-angle, a variable-angle ㊀, or a variable-angle ① single-wavelength radiation source tool source. The measuring step may also include one-phase measurement using a multi-discrete wavelength radiation source type working phase. The diffraction feature may be a reflection diffraction feature or a diffraction feature. In addition, the diffraction feature can also be a positive or negative diffraction feature or a higher-level diffraction feature. The main purpose is to provide a method that can analyze the difference in diffraction characteristics between a series of members with different focal grids, and place the focal point on it. Another purpose is to use reflection or transmission diffraction to obtain a data to determine or measure the parameters related to a lithographic apparatus. The parameters include the center of focus. A further purpose is to use any method available to generate diffraction characteristics that is limited to the "th" angle of the Oth or specular diffraction level or any higher diffraction level, which can be 5 wavelengths, variable phase, and variable polarization. Method to obtain a diffraction feature to determine or measure various parameters, including the parameters in the focus. The main advantage of the present invention is that it does not require the use of optics, SEM or similar

552464

V. Description of the invention (9) A microscope measuring tool can measure the same as a lithographic apparatus. Another advantage of the present invention is that it can be used in-step D parameter. A conventional wafer made of a photoresist lithography apparatus includes a conventional focal diffraction grating, and the difference between the diffraction gratings of these diffraction gratings is determined to determine the center of focus. Features and advantages of the present invention is that it provides a method and apparatus capable of obtaining various results within and between a lighthouse and a machine at a cost lower than conventional and known methods. For example, one step of the other purposes, advantages, novel features of the present invention, and a step into a cow ring, a part will be explained in detail in the following with drawings. Second, the scope of application will be apparent to those skilled in the art after viewing the following content, ^ ★ Part: Learned about the implementation. s To use the special application for profit-seeking scope; paragraphs and their combinations, you can achieve a variety of schematic diagrams of the invention and incorporate the following content and the drawings that form part of it, using r | An embodiment of the invention, and the following exemplified the principle of Tuming. These drawings are only used to illustrate one of the preferred embodiments of the present invention. The preferred embodiments should not be used to limit the present invention, in which ...

The first picture is a schematic diagram of a wafer with a plurality of grains on it, and the particles include a diffraction grating; ~ # The second picture is a schematic diagram of various modes for obtaining reflective Oth-level diffraction characteristics; The one shown in the figure is a 3 D diffracted light thumb;

552464 V. Description of the invention (10) The first four series of diffraction gratings are selected as shown in the fourth figure; the fifth series of diffraction gratings shown in the fifth series AC chart are characterized by diffracted eight-blade angle scattering. A series of polarized links S and / are obtained by calculation; * There is a difference in focus step between the blades, and a parabola with a small diffraction value determined according to the root mean square error of the focal point loss system: The eighth figure containing the narrow and wide focus centers is shown in the center of the focus in the scene, and the 3D map of the heart is obtained based on the diffraction feature difference showing the position f; and The focus shown in the ninth figure in the focus of the position function is the focus center obtained from the scene area. The plane A 楣 舢 / of the center of the diffraction feature difference point of the tlit is not used as the scene area. One of the position functions, “,,”, 3D chart of the effect of a thousand tilts of Zhanning ~. The preferred embodiment describes in detail the present invention provides a method and device for measuring the center of focus of a lithographic device phase: engraving device. In the = = = 得-series of diffraction features 'such diffraction light peach series = Shike device' and application It is made by several different focus settings and selective use of different dose settings of the right stem. Diffraction features are arranged in order, and this order can be made after obtaining the diffraction features, for example, set according to the poly: Order, and it should be in equal increment units < then it can be determined; the difference between the diffraction characteristics of the adjacent focusing uncertain diffraction gratings. Selectivity uses a measurement system, such as root mean square error analysis, Compare these differences based on. Etc. = Page 13 552464 V. Description of the invention (11) At the center of the coincidence point, the difference between the adjacent focus settings of these diffraction features 丨 Shi Zi's more concentrated set of signs that increase the net Difference handle 氺 / Λ. Therefore, using the diffraction feature difference knife analysis method of the present invention, no reference principle is needed.

(Scanning cat-type electron microscopy, such as an optical microscope or SEM, further describes the focal point and related parameters of the present invention. The lithographic apparatus is like the definition of the first ::: column. The solution is transferred to a substrate and Select the mask and transfer any of the devices—pictures, ancient photos, and images to it selectively. Tian + This is a conventional optical lithography lithography method. Special materials including other photoresist for image transfer to the wafer are coated on the crystalline and photoresist coating to prepare the circuit, and the wafer can be "softbake" processed if necessary. Type or negative < baked =: 通常] usually: soluble in chemicals used as photoresist developer; know: sense other parts but does not have a pattern of 2 hours or "dagger structure. As for optical lithography, it is used For example, a lamp is often used to illuminate the mask, and then the transmitted image is projected onto the resist film to achieve selective exposure. The lithographic apparatus described in the present invention includes a stepper (also known as a stepper). For the machine) 'It is used to project the image of a circuit or other structure from the photomask to ^ 52464 V. Description of the invention (12) Bright light τ m :: on the wafer. Stepper usually includes a miniature lens and a two-source light source on the platform, wafer platform (㈣ ... Wei Zuo Station. Stepper 'js), wafer E (wafer cassette) and operation can use the step-repeated Lin Λ semi-positive and negative photoresist two methods, it is too complicated to commit * step-scan format, or a combination of the two. ^ = A wafer or other substrate is used, and a diffraction grating system is used to "differentiate" the diffraction grating. Simply put, the diffraction light sets you to make periodic changes in the refractive index ... The lithographic installation of physical 2 or the island: structure or image. This change in refractive index may be caused by the difference or the difference. The physical difference includes a photoresist or other, such as using a kind of refractive index. Coordinated with air-^ j, (scored) ^^ The difference in chemistry includes wafers with diffraction gratings exposed by photoresist, and 4 wafers that have not been etched. In this case, all the resists are still present. The refractive index of the exposed part is different from that of the non-exposed resist, in order to produce a periodic change in the refractive index of the resist. Diffraction grating. J = The periodicity can be obtained by the periodicity of such structures or chemical elements. Therefore, this includes traditional diffraction gratings composed of a series of parallel lines, but also has periodicity in both the X direction and the γ direction. Gratings, such as columns or holes in a 3D (stereoscopic) array. The one shown in the second figure is a diffraction grating with periodicity in the X and γ directions, while the one shown in the first figure is a A plurality of parallel, springs 5 and 5 have a periodic diffraction grating in a certain direction. Therefore, the diffraction grating includes a photoresist grating, an etched thin film stack grating, a metal grating, and other gratings known in the art. The line-to-space ratio of the diffraction grating (1 ine 552464 V. Description of the invention (13) width to space ratio) is usually about 1: 1 to 1: 3. The dagger ratio can also be used. Taking a typical diffraction grating with an i: 3 ratio as an example, it can be used for: line width and pitch of 40 nm. Depending on the analysis j of the lithographic apparatus as part of the reason, this width and pitch can be greatly reduced. When the present invention is implemented, a diffraction grating is used to generate a diffraction feature. Diffraction features can be generated by using any of several instruments, such as scatterometers, ellipsometry meters, or reflectometers. Any penetration that uses radiation to generate diffraction features is referred to herein as a radiation source-based tool (too 1). Usually people use visible radiation source tools, such as light source tools, but the radiation source must be other than visible radiation, such as χ light source. ^ This device generates a birefringent pattern or feature by changing at least one diffraction related parameter. In the embodiment, the diffraction characteristic is generated in a reflection mode, in which radiation such as light is reflected. Therefore, if two = ;, the mi angle scatterometer can produce a diffraction characteristic, "It uses a known wavelength source earlier, and the incident angle ㊀ changes within a certain, internal. The one shown in the fifth figure is For the obtained diffraction characteristics, it plots the intensity of light according to the incidence and reflection angles. Another method is to use the laser beam source, and optionally adopt different incident angles, respectively. Another method is to use A wide-spectrum incident light source, as shown in the second diagram, in which the wavelength range is emitted, and the angle of incidence 选择性 is selectively maintained. Fan Ya uses a detector to detect the diffractive phase light source with a variable phase. This can be used as the source of polarization of the component or the polarization range of the component. Also, as shown in the second figure, the angle of incidence May also be in a range. 552464 V. Description of the invention (14) Grating rotation, or relative to the light source, can be, and is known to be: any one of the devices, or a combination or conversion of light intensity samples The diffraction characteristics of the target. In general, the wavelength of the light emitted by the person Incidence angle ㊀,. Diffraction feature can represent the first order, draw the spear's 0th or specular diffraction level, or any higher diffraction level. In addition, the transmission mode can also be planned with " Generate a diffraction feature, such as using an X-ray radiation source as a component of a radiation source tool. An embodiment of the present invention provides a wafer 10 as shown in the first figure, and a series of dies 15 are provided thereon. Each die usually indicates a defect on the wafer that belongs to the exposure field of a lithographic apparatus, such as a stepper. The step-and-repeat system illuminates the entire area of the reticle or light plate to be exposed when the shutter is turned on, so that the entire field of exposure of the grain is exposed at the same time. The step-scan system exposes only a part of the mask or light plate when the shutter is opened, so that only a part of the crystal grains are exposed to the scene. In either case, the reticle or light plate can be moved so as to produce a diffraction grating group 20, which is composed of a series of different diffraction gratings with different selective focuss. However, the diffraction grating group 20 may also be composed of a series of identical diffraction gratings, or a series of diffraction gratings having the same focus but different doses. In a preferred embodiment, the diffraction grating group 20 is composed of a series of diffraction gratings having different focal points, and preferably changed by a known and incrementable focusing step. The gratings are fixed doses. Crystals on wafer 10

Page 17 552464 V. Description of the invention (15) Capsules can be changed regardless of the dose range, focus setting range, or both. Traditionally, the dose or focus was changed in fixed increments, making it easier to perform subsequent analyses. Therefore, taking the focal point as an example, it can be changed in steps of 50 to 100 nm within a certain range, and taking the dosage as an example, it can be changed in increments of 1 or 2 mJ within a certain range. The diffraction grating 20 may use a plurality of conventional lines 25 separated by a space 30, or may use a 3D pattern as shown in the third figure. With works intended to illuminate the area, you can also choose the chemical change of the material when the optical system is changed in place. Because in the examples, other examples can be driven. The process can be affected by the resistance range used. The various layers of the photomask are usually applied to the radiation source on the other side of the photomask. "Receiving radiation" will change the potential of the resist and can be used to produce a potential chemical reaction or develop the resist with a developing system, the agent is a positive or negative resist layer, and other films can be produced. In terms of method and device, the shape, size, and configuration of the corresponding material on one side of the resist material cover can cause a photoresist layer on the resist layer. Insert one between the reticle and the reticle or be excited to produce an opaque and transmissive grating. Between the contact and the space dosing layer, the upper lens or its reflection in the resist represents the resistivity of the resist material. Bake in a solid, so as to implement a chemical display in another. This part is called a post-cut system. If it is set thereon, it will form an in-image in the present invention, and a wafer diffusion resist as in the previous image. Cheng 'can thus be decided by removing a type. Selectively in the basal money engraved area 'allows the diffraction to be full and potential image. The components that cause the diffraction characteristics of the resist layer to irradiate after acceptance. Selective use of part of the resist development process also plate materials, such as space. Raster exposure but

5. Description of the invention (16) No development 'or alternate development. The same goes for a traditional grating generator, although the large system described above includes the use of a phase shift mask, various light-emitting methods can be used, such as beam irradiation. Any one of them, including electrons, is an important parameter for any lithographic device, including dots. Focus and 隹 = 刻 engraving device, focal quantum, and focus, or from the lens to the eyepiece, page 4 or imaging of radiant energy in a specific illumination field range s ^ ^ ㈣ ㈣ function. The obtained result must be good within a clear usable focal temperature, and the factors will also affect the focus and depth of focus, including factors other than the i μ point, and the wafer platform on the X ”axis. Machine with a resolution of about 0.15m.25 microns and a step size of 1.50 microns. J / wood is about 0 · 40 to so 'in terms of effective operation of the lithographic apparatus, such as during a 2-block exposure step The stepper is determined to be fixed. [Force: the sum of the work = the change in quantity makes it difficult to read this center: two; the lens used in the eight-blade lithography device has a very deep focal depth ^ 2 Must have very high precision. A lens that is in focus will produce a 'two-tone photoresist image, and out-of-focus will result in non-functional photoresistance characteristics.!: Jin :: medium: can also be significantly improved Repeatability of the process. Once the "focus" is known, various autofocus systems or bodies can be used to determine the distance between the lenses and keep the wafers fixed. Such as the optical method using reflected light, the capacitive method ', and the pressure-sensing method such as producing and pressing air. However, these systems and systems cannot determine $ == 552464 V. Description of the invention (17) The center can only be centered on the lens, and must be centered at each point of the lithography device. Focusing step to the next specular order. The photoresist for the diffraction grating is exposed in incremental focusing steps after the photoresist is exposed but the structure is etched into the resist substrate. Then measure Diffraction features, such as recording gratings, are the focal point under ideal conditions of diffraction theory that can sense the next step distance of diffraction features including, but not limited to, the first and chirped diffraction features. Therefore, as shown in the fifth figure, the diffracted light thumb is the same in the fifth figure. There is no significant difference between the two. As shown in the fifth figure, the distance between the target wafers remains fixed. In a typical operation, it takes six hours. At the following frequencies, it is determined periodically that the focal point is not a radiated light source with a fractional scattered light. The diffraction characteristics represent the specular order from a focal distance (focusing steps η and η + 1) in the fifth figure. Fixed-dose magic Light ▲ and the focal point or the distance from the lens to the wafer is changed. The resulting diffraction characteristics are obtained before or after development, in-layer and selectively etched to include a series of diffractions of the wafer Grating and record the known memory of the processor-related device. Any structure of the repetitive or periodic characteristics of diffracted light, & structure of the image. Mirror level, or any poor analysis, is based on Measure the difference from a focus step ^ as the difference. As you approach the center of the focus, the difference in the feature of the focus becomes smaller and smaller. At the center of the point = the point with the smallest change in diffraction characteristics is shown. At the center, the distance separating adjacent diffractions from their diffraction features is reduced, and the known diffraction features substantially overlap, and the diffractions of the adjacent focusing steps are known when compared with each other.

Page 20 552464 V. Description of the invention (18) Features ′ The diffraction feature difference from a focus step to the next step can be confirmed, and the focus center can be determined. However, this method requires the judgment of the operator and is not directly measurable and slower. Therefore, any of various measurement systems and analysis methods can be used to measure the diffraction characteristic difference from a focus step to a next step. Such methods include, but are not limited to, minimizing mean square error (MSE) or root mean square error (RMSE), and other Euclid distance measurement methods. These methods also include averaging, weighted average ', the sum of averages, and other methods that highlight (c h a r a c ^ e r 丨 z e) diffraction feature differences. In one embodiment, the diffraction characteristics are obtained from a series of winding gratings 40, 45, 50, 50, and 50 having different focus settings in sequence as shown in the fourth figure. When the RMSE difference between 40 and 45 is determined, it means the diffraction characteristic difference of the diffraction grating 40 corresponding to the focus setting. When the average RSME difference between 40 and 45 and between 45 and 50 is determined, it indicates the diffraction characteristic difference of the diffraction grating 45 corresponding to the focus setting. When the average RSME difference between 45 and 50 and between 50 and 55 is determined, it means the diffraction characteristic difference of the diffraction grating 50 corresponding to the focus setting. Similarly, when the average RSME difference between 50 and 55 and between 55 and 60 is determined, it means the diffraction characteristic difference of the diffraction grating 55 corresponding to the focus setting. The RSME difference between 55 and 60 is taken as the diffraction characteristic difference of the diffraction grating 60 corresponding to the focusing setting. Therefore, this method generates a series of diffraction feature differences corresponding to the difference in focus settings between diffraction gratings having sequentially different focal points. Once the diffraction feature difference is known, a weighted average can be determined and used to determine the center of focus. In one such embodiment, the following

Page 21 552464 V. Description of the invention (19) Column equation (1) to determine the center of focus: y (focus step) (!) (DSDrwse) 2 T _I_ (DSDrwse) 2 and DSDRMSE is the RMSE diffraction feature Difference where C 0 F is the center of focus (DSD). The numerical representation of each diffraction feature difference can also be compared in other ways to determine that the focus center is the focus setting corresponding to the area with the smallest difference between the diffraction gratings of adjacent focus settings. This numerical value indicates that it can be plotted according to each focus setting step, and thus a graph as shown in FIG. 6 is obtained, in which a parabolic curve centered on the focal point is shown as a track. In the focus: at the slope of the parabolic curve is close to zero, so this position further shows: before the focus center is determined in the area with the smallest difference between the diffraction gratings of the adjacent focus settings, remove either When a defective product is exposed to a diffraction grating, the individual diffraction gratings may also be due to exposure errors and resist lithography specific lithography equipment, such as the known parabolic curve, and the tight parabola shown in Figure A is given, with a few focus To set the correspondence, various filters can be used first. In particular, if the focus curve obtained in essence is not specific to the focus setting, the depth of focus or hardening of the stepper is further produced. The right is the edge map function. Because it contains the most, the depth of focus also follows and related mathematical models. The out-of-focus focus setting may become weird. Related reasons, such as abnormal results. The solidity can be analyzed to have the same as the seventh, poor area system and small. If it is a drawing function

Page 22 552464 V. Description of the invention (20) The number has a broad parabola as shown in Figure 7B, that is, the area of the table ... is large, so the depth of focus is also large, so that it can be seeded, inspected, and minimized. The setting provides a good focus value. To obtain a parabolic response ’, the center of focus must be included in the incremental focus setting range of the diffraction grating exposure. That is: Er J: The range does not include the center of focus, and it is impossible to produce the ㈣ that should be = at the point of 隹.; In addition, on a significant defocus = two distances right: 疋 王 Removes the inhibitor •, then from One gather: The diffraction characteristics of the step distance may be very close. This is not to cause any significant difference in the focus image of the various gathers + the shadow obtained can also use a grating model Ge Jun spoon ^ ^ & : Solid function. In this area. Usually, this ί = is used to determine the significant and out-of-focus points and two points are plotted on a parabolic curve. Section: The example shown in the figure is used as an incident angle The function S ^ Pi, 3 and where 疋 connects and plots S and according to the diffraction intensity, a polarization, but can be easily understood *, in other diffraction modes, the diffraction characteristics are plotted. Therefore, for variable wavelength diffraction, The diffraction characteristics are generated by plotting the wavelength according to Zhao =. For the surface and surface, the variable polarization state is plotted according to the intensity, and for the variable directional diffraction, the intensity is plotted according to the intensity. Similarly, the first Although the diffraction features of the five figures are derived from reflection diffraction, transmission diffraction can also be used. Obtain a similar diffraction feature, as long as the radiation source tool for diffraction can be transmitted through at least a part of the diffraction grating, so that it can be obtained with an X-ray radiation source tool, or for a light source tool In other words, a transparent or translucent diffraction grating and substrate can be used.

552464 ^-5. Description of the invention (21) 0 t h or mirror-level diffraction Similar results. It is understood that when the obtained diffraction features are the best when generating the center of focus as shown in the sixth figure, interpolation between points is performed in order to be more technically known, and each focus may or may not be used to perform preliminary analysis. However, it is also intended to focus on the setting but can also be obtained by using any higher diffraction level. For most embodiments, the comparison is made from the same firing level. Not a chart, or in generating the solution shown in Equation ⑴, statistical techniques are used to determine the focal point of each focal point accurately. These methods belong to this application. Similarly, the analysis method used is based on the diffraction feature difference of multiple focus settings. The incremental difference between the set step distances should be kept at a fixed step distance. If the step distances are inconsistent, the interpolation method can be used, which is lower than 0. 〇7 devices, such as dose focus with focus center 'for example, the diffraction result is a' use of a series of focus points as described above to obtain the effective dose setting method of the micrometer classic stepper The diffraction of the 2G series of the grating group determined by the center of the point is analyzed, and the center can be applied. In this way, the center of the step size range can be gathered with a similar focal range. The focus curve can be confirmed in micrometers by drawing with diffraction features obtained from each of the step groups. Lithography. Depending on the package raster group varies. the amount. It can be connected with the features of grating group. The amount of focus curve, focus-type focus resolution effect can be different. A dose sign of the radiation grating. For example, according to the method of the agent, the choice is usually low. Therefore, the method of pre-generating a series of methods varies with different tools and is a series of The characteristic difference is based on having the most or focal depth greater than 0.03, which can analyze the diffraction analysis of each diffraction of the known agents of the column diffraction grating group to know that the strong focal effect of the agent is the most important.

Page 24 552464 (22) V. Description of the invention Amount setting. It is also obvious that 'using the diffraction feature difference, for example, and the position of the diffraction grating in the field of view 2 = unconventional can be a wafer platform, you can draw as the focus of a field: = number The center is the one shown in the eighth figure. The table can show the image I, astigmatism of the 2 systems, or cause the center of focus of the scene to be different from it. Similarly, as shown in the ninth figure, the x & y axis and its tilt (t i 11) can also be plotted, thereby showing the platform tilt effect as the focal point of the tilt of the Canadian hall. At first glance, this method and device can also use the method and device to match the focal characteristic determined by the diffraction feature difference to a known theoretical or actual diffraction feature difference information database. The matching information database can be much smaller than the traditional theoretical information database that must contain a very wide range of errors, and can be generated more quickly. As a theoretical information database, its storage requirements are smaller The analysis time is faster. The method and device of the present invention can also be used for quality control testing, including analysis of the center of focus determined by other parties. This can be done with some of the aforementioned angular scatterometers. Its related computer system, or together with other appropriate devices capable of performing the aforementioned measurements. Using a fractional scatterometer, the diffraction characteristics are divided into different diffraction levels from each angular position specified by the grating equation (2). : Sin ㊀ i + sin θη = η Λ / d (2) where ㊀1 is the angle of incidence, as a negative angle, θη is the angular position of the nth diffraction order, 'λ is the wavelength of the incident light, and d is the diffraction Raster space

Page 25 552464 ----- V. Description of the invention (23) Period or interval. Because the angle of incidence is equal to the mirror level, the relationship can also be used as a diffraction feature to generate. The level can be used, and the wavelength λ is an appropriate method of the present invention, and can be determined in a law. The other way is that the present invention can focus the system, so the focus is confirmed, and the scope of the invention is exemplified by the above.倶 ′ is the present invention, so you can see the surface diffraction, and like other diffraction modes. With wave change, law and equipment include accepting or adjusting. It is used for self-contained related convenience examples to mention only the unknown application, for the Oth or mirror diffraction level, the angular position of the step. However, a suitable angular position other than the mirror surface is determined as described above. A similar pattern of radiant features produces the basis of the pattern, so that for any statement 'regardless of the specular diffraction order or other higher radiating length analysis devices, the angle ㊀i can maintain a fixed solution of the equation θη. Of it. The setting can also be used to determine the focus center, so that any computer-based control system can be used to adjust the optimal center. When the best focus is determined, the formula of the present invention can be used to determine the dose change or the known dynamics of the art. The focus center is used to control the system to 'for example' dose change to determine the pupal point using information from an automatic poly-diffraction feature analysis. ! It is only to explain the present invention, not to limit the present invention, the scope of various modifications or changes in the spirit of the invention.

552464

Brother Θ 疋 —a crystal with several grains on it including a diffraction grating; a schematic diagram of a circle; the second graph is—intent; a third diagram of various modes to obtain reflective Oth order diffraction characteristics The one shown is a 3D diffraction grating; the one shown in Figure 4 is a series of diffraction gratings; the one shown in Figure -C is obtained by using a fractional scatterometer to obtain a series of drawn diffraction features. This feature has a different focus step, and the two polarization links S and P. The sixth figure is a chart of the diffraction difference determined by the root mean square error drawn according to the focus; '$ seventh The ones shown in Figures A and B are parabolic curve charts containing the minimum values of the narrow and wide focus centers, respectively. The one shown in Figure 8 is to find the center of focus from the diffraction feature difference of many positions in the scene. A 3D chart showing the center of focus as a function of position in the scene; and the one shown in Figure 9 is the center of focus obtained from the diffraction feature difference of a tilted surface in the scene, showing 3 D of the platform tilt effect as the focal center of a position function in the scene Table.

Page 27

Claims (1)

552464 A method for measuring various parameters related to a photolithography device includes the following steps: ^ ^ ^ a substrate, which is provided with a plurality of diffraction gratings using a photolithography device and a photolithography process; The diffraction gratings include a number of separated New Year's Day: a radiation source tool, measuring at least three s-diffraction features of several diffracted lights; and determining the difference between the diffraction features to determine the lithography Desired parameters of the device 2. Like a wafer. 3 · If the tool includes 4 · If the tool includes a range of eyebrows 5 · If the tool includes a 6 · If the tool includes 7 · The method described in item 1 of the patent scope of Shenjing, its patent application The method described in item 1 of the scope of patent application of a light source type worker, wherein the radiation source type tool. Diffraction feature patent Fan Angular Scatterometer Shen Jing Patent Fangan laser beam source patent application method described in item 3, wherein the light source type incident laser beam source, focus the laser beam and An optical system at each incident angle, and the method described in item 4 for detecting the obtained measurement angle of a detector, wherein the method described in item 3 is used for the light source type, and 〇 A method described in item 3 of an optical range including a wide-spectrum, long-range illumination, wherein the light source is an industrial light source, which focuses the light and cuts a certain incident system, and is used to measure the obtained Wavelength ^ 552464, A scope of patent application A detector with known diffraction characteristics. 8 · The method as described in item 3 of the scope of patent application, wherein the light source type tool includes an incident light source, and several are used to change s and? The component of the magnitude and phase of polarization is an optical system that focuses the light beam and illuminates a range of incident phases, and a detector for detecting the phase of the diffraction characteristic obtained. 9. The method according to item 1 of the scope of patent application, wherein the step of measuring the diffraction characteristics includes using a wide-spectrum radiation source tool source operating at a fixed angle, a variable angle ㊀, or a variable angle Φ Take a phase measurement. 10. The method according to item 丨 of the patent application scope, wherein the step of measuring the surrounding feature includes using a single-wavelength radiation source tool source operated at a fixed angle, a variable angle ㊀, or a variable angle Φ Phase measurement. 11. The method of claim 1, wherein the step of measuring diffraction characteristics includes performing phase measurements using a multi-discrete wavelength source source tool. '+ 进 Where the diffraction feature Where the diffraction feature Where the diffraction feature Where the diffraction feature 12. The method described in item 1 of the scope of the patent application is a reflective diffraction feature. 13. The method described in item 1 of the scope of patent application is a transmission diffraction feature. θ 1 4 · The method described in item 1 of the scope of patent application is a mirror-level diffraction feature. 15. The method described in item 1 of the scope of patent application is a diffraction feature with a higher diffraction level. Engraving device and the method as described in item 1 of the scope of patent application 552464 6. The scope of the patent application determines two diffraction gratings adjacent to the focus setting, wherein the diffraction feature difference between the two diffraction gratings is lower than that of the other two adjacent focus settings. Therefore, the parameter is the focal center of the lithographic apparatus. 17. The method as described in item 16 of the scope of the patent application, wherein the known different focus settings are different focus settings in equal increments. 18. The method as described in item 16 of the scope of patent application, wherein the known different focus settings are different focus settings of unequal increments, and the method further includes using a mathematical algorithm to allow different focus settings of unequal increments normalization. 19. The method as described in item 16 of the scope of patent application, wherein the difference in diffraction characteristics between the diffraction gratings is increased by an approximation of a parabolic curve with a slope of zero at the center of the focus. 20. The method according to item 1 of the scope of the patent application, wherein the step of determining a difference in diffraction characteristics between the diffraction gratings includes using a measurement system to determine the difference. 21. The method described in item 20 of the scope of patent application, wherein the measurement system is a data analysis method of root mean square error. 2 2 The method as described in item 1 of the scope of the patent application, wherein the step of determining the minimum I includes a comparison of the weighted average of the diffraction feature differences between the diffraction gratings. 2 3 · The method as described in item 1 of the scope of patent application, further comprising using a lithographic apparatus with the same focus setting to form a plurality of diffraction gratings, and determining the difference between each other for use as the diffraction gratings on the substrate. A position function. 24. The method as described in item 1 of the scope of the patent application, further comprising using known different focal lengths and known different agents; g; set to form a number of diffracted lights Page 30 552464 VI. Patent Application Scope '_ 1 "-Grid' and determine the effect of dose on focus. β 2 5 · The method described in item 23 of the stated patent scope, in which 4 volumes of diffracted light include several groups of the same diffraction gratings known to have an out-of-focus setting. These 1¾ groups use different known Dose settings vary. 26. A method for determining the center of focus of a lithographic apparatus, comprising the steps of: providing a substrate on which a plurality of diffraction gratings made using the lithographic apparatus are provided; Known focus settings; use a radiation source tool to determine at least three diffraction characteristics of several diffraction gratings;-measure the differences between diffraction characteristics of adjacent grating settings for diffraction gratings; and read the settings As the focus center of the focus setting, the diffraction characteristics of the diffraction gratings of adjacent focus settings have the smallest difference. " J: · The method as described in item 26 of the scope of patent application, wherein the diffraction characteristic difference between the diffraction gratings of the adjacent focus settings is an approximation of a parabolic curve with a minimum difference slope of ^ zero . 28. The method according to item 26 of the scope of patent application, wherein the difference in diffraction characteristics between adjacent focusing diffractive diffraction gratings is determined: including using a metric system to determine the difference. ^ Package 29. The method described in item 28 of the scope of patent application, wherein the measurement system is a data analysis method of root mean square error.疋 30. The method described in item 26 of the scope of patent application, in which the minimum is determined ^ 2464 The difference step includes the step of weighting the flat focus difference of the phase difference into the ‘said, τ adjacent focus setting, and the difference of the difference! : The method of 3 range item 26; the method in which the minimum interdiffraction teco to the% -ray grating set for the i-neighbor focus is applied to the data obtained from each other ^ u.., To a spread curve, This causes the minimum difference to include the minimum of the 3-sided parabolic curve. "The method described in item 26 of the scope of patent application, wherein the substrate includes the method described in item 26 of the patent scope, wherein the radiation source tool includes a light source tool. 34. The method as described in item 33 of the scope of patent application, wherein the light source type II includes an incident laser beam source to focus the laser beam and to an optical system with an incident angle = scanning, And a detector for detecting the diffraction characteristics obtained from the obtained measurement angle. 35. The method as described in claim 34, wherein the light source tool includes a fractional angle scatterometer. 36. The method as described in item 33 of the scope of patent application, wherein the light source type tool includes a right dry laser beam source. 37. The method according to item 33 of the scope of patent application, wherein the light source type tool includes a wide-spectrum incident light source, an optical system for focusing the light and dry-illuminating a certain incident wavelength, and an A detector that measures the wavelength characteristics and the diffraction characteristics obtained. 3. 38. The method as described in item 33 of the patent application, wherein the light source type tool includes an incident light source, and several are used to change the amplitude and phase of the S and P polarizations. 552464 39. Feature Φ operation 40 · Feature Φ operation 41 · Feature line phase ‘Make this’ and use as a kind of application step package as a kind of application step package as a measure of application step package. Focusing on the beam and detecting the obtained patented patents using a wide range of light patented patents using a single-wavelength patented patents using a range of 26 to a fixed radiation source 26th to a fixed radiation source 26th The term "fixed angle" of the diffraction term is used to describe the characteristic phase of the discrete wave described by the tool & term, a method to perform by a variable angle source, and a method by a variable angle source A long-range radiation source illumination has a detection method Θ or a phase measurement method and a phase measurement method or a phase measurement tool. Variables around variable quantities. Quantitative diffraction source 4 2 · The method described in item 26 of the patent application range, wherein the diffraction feature is a reflective diffraction feature. 4 3. The method as described in item 26 of the scope of patent application, wherein the diffraction feature is a transmission diffraction feature. 44. The method of claim 26, wherein the diffraction feature is a specular-level diffraction feature. 4 5. The method as described in item 26 of the scope of patent application, wherein the diffraction feature is a diffraction feature of a higher diffraction level. 46. The method as described in item 26 of the scope of patent application, wherein different focus settings include a fixed difference between sequentially different focus settings. 47. The method as described in item 26 of the scope of patent application, wherein different known focus settings are different focus settings of unequal increments, and the method further includes using a mathematical algorithm to allow different focus of unequal increments. Set normalization. 33rd Tribute