TW202001187A - Inspecting device of gratings and inspecting method of same - Google Patents

Abstract

An inspecting device of gratings and an inspecting method of the gratings are disclosed. The inspecting device has a sample carrier horizontally movably disposed on a first slide rail for carrying a substrate having a grating structure; a laser source disposed above the sample carrier to provide a laser beam having a wavelength and being incident to the substrate by an incident angle; a light detector moveably and rotatably disposed on a second slide rail to capture a diffraction light from the substrate, wherein the second slide rail is parallel to the first rail; and a data processor connected with the light detector to calculate and output a period of the grating structure. The inspecting method is performed by using the inspecting device of the gratings to obtain the period of the grating structure.

Description

Grating detection device and detection method

The invention relates to a grating detection device and a detection method, in particular to a method of detecting a diffracted light emitted by a grating structure, obtaining a period of the grating structure from the position of the diffracted light, and then detecting the grating Grating detection device and detection method for structural uniformity.

After the laser enters the grating at a specific angle, in addition to the reflected light at the same incident angle, at least one diffracted light will appear according to the grating period, material, and environmental refractive index. Generally speaking, after measuring the diffraction angle of the diffracted light, the grating period can be known from the formula, and the intensity of the diffracted light can reflect the grating quality.

The characteristics of the grating element are affected by many factors. If the material absorption is not considered, it is mainly determined by the period, fill factor and thickness. Scanning electron microscopy (SEM) or atomic force microscopy (AFM) is often used to measure the surface structure and undulating topography. The inspection period, thickness and fill factor are used to judge the grating characteristics; or the diffraction system is used to judge The characteristics of the grating use the detection diffraction efficiency and the period as the reference coefficient of the grating, but the topography or side profile of the grating cannot be actually observed. Therefore, the grating quality can be judged by SEM or AFM and diffraction system respectively. However, the currently known diffraction system architecture cannot perform fast and large-area grating inspection, and has no advantage over scanning electron microscopes or atomic force microscopes.

Therefore, it is necessary to provide a method to solve the problems in the conventional technology.

The main object of the present invention is to provide a grating detection device and a detection method thereof, which utilize a horizontally moving object carrier and a rotatable and movable photodetector to improve the detection accuracy. Since the angle at which the laser light is incident on the test object carrier is fixed during the detection process, different diffracted light exits will be generated according to the different periodic grating structures of the test substrate on the test object carrier. The grating detection device of the invention can use the moving distance of the photodetector, the vertical height of the photodetector and the incident angle to determine the grating period, and has the advantages of simple structure, fast detection speed and high accuracy.

其中Λ代表該週期，λ代表該雷射光束的該波長，θi代表該入射角，x是該光偵測器補捉到該繞射光的位置處與該待測物載台之間的一水平距離，以及h是該光偵測器捕捉到該繞射光的位置處與該待測物載台之間的一垂直高度。 To achieve the above objective, an embodiment of the present invention provides a grating detection device, which includes: a test object carrier, which is horizontally and movably arranged on a first slide rail, the first slide rail is a two-dimensional The slide rail is used to carry a substrate, wherein the substrate has a grating structure; a laser light source is disposed above the object to be tested to provide a laser beam, wherein the laser beam has a wavelength, and Incident on the substrate at an incident angle; a light detector is movably and rotatably provided on a second slide rail for capturing a diffracted light emitted from the substrate, wherein the second slide rail and The first slide rails are parallel to each other; and a data processor is connected to the light detector to calculate and output a period of the grating structure; wherein the period is calculated by the following formula (I):

Where Λ represents the period, λ represents the wavelength of the laser beam, θi represents the angle of incidence, and x is a level between the position where the light detector captures the diffracted light and the object carrier The distance, and h is a vertical height between the position where the light detector captures the diffracted light and the object carrier.

In an embodiment of the invention, the photodetector is a position sensitive device (PSD).

In an embodiment of the invention, an angle at which the diffracted light enters the light detector is equal to or approximately equal to 90 degrees.

In an embodiment of the invention, the data processor calculates a diffraction efficiency of the diffracted light, the diffraction efficiency being an energy of the diffracted light received by the light detector divided by the laser beam A light energy.

In an embodiment of the invention, a beam expander is further included for adjusting a diameter of the laser beam and focusing the laser beam on the substrate.

其中Λ代表該週期，λ代表該雷射光束的該波長，θi代表該入射角，x是該光偵測器補捉到該繞射光的位置處與該待測物載台之間的一水平距離，以及h是該光偵測器捕捉到該繞射光的位置處與該待測物載台之間的一垂直高度。 Another embodiment of the present invention provides a grating detection method, which includes the steps of: providing a substrate, wherein the substrate has a grating structure; placing the substrate on a test object stage, wherein the test object stage is horizontal Movably disposed on a first slide rail, the first slide rail is a two-dimensional slide rail; a laser beam is incident on the substrate at an incident angle, wherein the laser beam has a wavelength; use a The light detector captures a diffracted light emitted from the substrate, wherein the light detector is movably and rotatably disposed on a second slide rail, the first slide rail and the second slide rail are parallel to each other; and A data processor is used to calculate and output a period of the grating structure; wherein the period is calculated by the following formula (I):

Where Λ represents the period, λ represents the wavelength of the laser beam, θi represents the angle of incidence, and x is a level between the position where the light detector captures the diffracted light and the object carrier The distance, and h is a vertical height between the position where the light detector captures the diffracted light and the object carrier.

In an embodiment of the invention, the photodetector is a position sensitive device (PSD).

In an embodiment of the invention, an angle at which the diffracted light enters the light detector is equal to or approximately equal to 90 degrees.

In an embodiment of the present invention, the step (5) further includes a step: calculating a diffraction efficiency of the diffracted light, wherein the diffraction efficiency is an energy of the diffracted light received by the light detector Divided by the outgoing light energy of the laser beam.

In an embodiment of the invention, before the laser beam is incident on the substrate, it further includes using a beam expander to adjust a diameter of the laser beam so that the laser beam is focused on the substrate.

1‧‧‧ First slide

2‧‧‧Test object carrier

3‧‧‧ substrate

4‧‧‧Laser light source

5‧‧‧Light detector

6‧‧‧Second Slide

Li‧‧‧Laser beam

Df‧‧‧diffracted light

h‧‧‧Vertical height

x‧‧‧Horizontal distance

θi‧‧‧incidence angle

Figure 1: A schematic diagram of a grating detection device according to an embodiment of the invention.

FIG. 2 shows the measurement results of the grating structure with the gradient period of 381 nm to 612 nm using the grating detection device, scanning microscope (SEM) and atomic force microscope (AFM) of the present invention respectively.

FIG. 3 shows the measurement results of the grating structure with the gradient period of 263 nm to 337 nm using the grating detection device, scanning microscope (SEM) and atomic force microscope (AFM) of the present invention.

Fig. 4 shows the measurement results of the grating structure with the gradient period of 209 nm to 233 nm using the grating inspection device, scanning microscope (SEM) and atomic force microscope (AFM) of the present invention respectively.

In order to make the above and other objects, features, and advantages of the present invention more comprehensible, the preferred embodiments of the present invention will be specifically described below in conjunction with the accompanying drawings, which will be described in detail below. Furthermore, the terms of direction mentioned in the present invention, such as up, down, top, bottom, front, back, left, right, inner, outer, side, surrounding, center, horizontal, horizontal, vertical, longitudinal, axial, The radial direction, the uppermost layer or the lowermost layer, etc., are only the directions referring to the attached drawings. In addition, the singular forms "a", "an" and "said" mentioned in the present invention include plural references unless the context clearly dictates otherwise. The numerical range (such as 10%~11% A) includes upper and lower limits (ie 10%≦A≦11%) if there is no specific description; if the numerical range does not define the lower limit (such as B less than 0.2% , Or B below 0.2%), it means that the lower limit may be 0 (that is, 0%≦B≦0.2%). The above terms are used to illustrate and understand the present invention, not to limit the present invention.

上述公式(I)中，Λ代表該週期，λ代表該雷射光束Li的該波長，θi代表該入射角，x是該光偵測器5補捉到該繞射光Df的位置處與該待測物載台2之間的一水平距離，以及h是該光偵測器5捕捉到該繞射光Df的位置處與該待測物載台2之間的一垂直高度。該入射角θi介於0至90度之間，可例如是65度、60度、55度、45度、30度、20度或15度，然不限於此。該入射角θi與該光柵結構的該週期有關，當該週期越小，該入射角越大，例如，入射角為65度可用來檢測週期為200~300奈米的光柵結構。 In order to quickly and accurately measure the grating period and diffraction intensity, please refer to FIG. 1, a grating detection device according to an embodiment of the present invention mainly includes: a test object carrier 2, which is horizontally and movably arranged at A first slide rail 1 is used to carry a substrate 3, wherein the substrate 3 has a grating structure; a laser light source 4 is disposed above the object carrier 2 to provide a laser beam Li, The laser beam Li has a wavelength and is incident on the substrate 3 at an incident angle; a photodetector 5 is movably and rotatably disposed on a second slide rail 6 for capturing A diffracted light Df emitted from the substrate 3, wherein the second slide rail 6 and the first slide rail 1 are parallel to each other; and a data processor (not shown) is connected to the light detector 5 for calculation And output a period of the grating structure; wherein the period is calculated by the following formula (I):

In the above formula (I), Λ represents the period, λ represents the wavelength of the laser beam Li, θi represents the incident angle, and x is the position where the photodetector 5 captures the diffracted light Df and the pending A horizontal distance between the object carrier 2 and h is a vertical height between the position where the light detector 5 captures the diffracted light Df and the object carrier 2. The incident angle θi is between 0 and 90 degrees, and may be, for example, 65 degrees, 60 degrees, 55 degrees, 45 degrees, 30 degrees, 20 degrees, or 15 degrees, but is not limited thereto. The incident angle θi is related to the period of the grating structure. When the period is smaller, the incident angle is larger. For example, an incident angle of 65 degrees can be used to detect a grating structure with a period of 200 to 300 nm.

Preferably, the laser light source 4 may be a solid-state laser, but it is not limited to this, and can be adjusted according to the required detection period range. Generally speaking, the minimum detectable period is the wavelength of the laser beam 0.5 times. In an embodiment of the present invention, the light detector 5 is preferably a position sensitive device (PSD), which can automatically track the position of the diffracted light with the highest intensity, so the data processor can be used to obtain the light The displacement distance x and rotation angle of the detector 5. Preferably, the angle at which the diffracted light Df enters the photodetector 5 is equal to or approximately equal to 90 degrees, so that the position where the diffracted light is received during each measurement can be controlled to be approximately the maximum diffracted light intensity to reduce measurement errors. Preferably, the data processor can also be used to calculate a diffraction efficiency of the diffracted light, the diffraction efficiency being an energy of the diffracted light received by the light detector divided by an output light of the laser beam energy. In addition, in an embodiment of the present invention, a beam expander may be further included between the laser light source 4 and the object carrier 2 for adjusting the diameter of the laser beam, and the The laser beam Li is focused on the substrate 3 of the test object stage 2.

According to the grating detection device of the present invention, the first slide rail 1, the second slide rail 6 and the photodetector 5 can be used to achieve a movable and rotatable position for capturing the diffracted light and control the winding The angle at which the incident light enters the photodetector 5 tends to be vertical, and at the same time, it is matched with the object carrier 2 that can move horizontally. Since the substrate 3 is driven by the object carrier 2, it can perform horizontal Two-dimensional displacement (that is, the substrate 3 can be maintained to move on a plane), so fast multi-point scanning can be performed at a fixed incident angle, and the grating period and diffraction efficiency on the substrate 3 can be obtained after calculation The rapid and accurate detection of the uniformity of the large-area grating structure is very different from the traditional scanning electron microscope or atomic force microscope that can only detect a small-area grating structure and takes a long time.

Please continue to refer to FIG. 1, another embodiment of the present invention provides a grating detection method, which includes the steps of: (1) providing a substrate 3, wherein the substrate 3 has a grating structure; (2) the substrate 3 is placed in a The object to be measured 2; (3) A laser beam Li is incident on the substrate 3 at an incident angle; (4) A light detector 5 is used to capture a diffracted light Df emitted from the substrate 3; And (5) use a data processor to calculate and output one cycle of the grating structure. The following describes each step in detail.

In the grating detection method, first of all: (1) Provide a substrate 3, wherein the substrate 3 has a grating structure. In this step, the substrate 3 is used as a test object, and the grating structure may have a one-dimensional periodic structure or a two-dimensional periodic structure.

In the grating detection method, the following is: (2) The substrate 3 is placed on a test object carrier 2. In this step, the object carrier 2 is horizontally and movably arranged on a first slide rail 1. That is to say, the object-to-be-measured stage 2 only performs two-dimensional horizontal displacement without performing any rotation or changing angle.

In the grating detection method, the following is: (3) A laser beam is incident on the substrate 3 at an incident angle. In this step, the laser beam has a wavelength. The laser beam is provided by a laser light source 4, which may be, for example, a solid-state laser light source, but it is not limited thereto.

In the grating detection method, the following is: (4) A light detector 5 is used to capture a diffracted light emitted from the substrate 3. In this step, the light detector 5 is movably and rotatably disposed on a second slide rail 6, the first slide rail 1 and the second slide rail 6 are parallel to each other. In other words, the light detector 5 can be moved horizontally and can be rotated to change the angle to facilitate receiving the diffracted light. Preferably, the angle at which the diffracted light Df enters the light detector 5 is equal to or approximately equal to 90 degrees, so that the position at which the diffracted light is received during each measurement can be controlled to be approximately the maximum diffracted light intensity to reduce measurement errors .

In the grating detection method, it is followed by: (5) using a data processor to calculate and output a period of the grating structure, wherein the period is calculated by the following formula (I):

In the above formula (I), Λ represents the period, λ represents the wavelength of the laser beam, θi represents the incident angle, and x is the position where the light detector captures the diffracted light and the object to be measured A horizontal distance between the stage 2 and h is a vertical height between the position where the light detector captures the diffracted light and the object carrier 2 to be measured.

In an embodiment of the present invention, the step (5) further includes a step: calculating a diffraction efficiency of the diffracted light Df, wherein the diffraction efficiency is the diffracted light Df received by the light detector 5 An energy of is divided by an outgoing light energy of the laser beam Li. The light output energy refers to the initial energy of the laser beam Li when it is emitted from the laser light source 4. The diffraction efficiency is mainly related to the fill factor and thickness of the grating structure, so the uniformity of the grating structure can be known from the diffraction efficiency.

Preferably, the photodetector 5 is preferably a position sensitive device (PSD), which can automatically track the position of the maximum intensity of the diffracted light, so the data processor can be used to obtain the photodetector 5 Displacement distance x and rotation angle. The data processor may be, for example, a computer host, which uses automated calculations or inspection programs to confirm the position of the diffracted light captured by the light detector 5.

Preferably, the above steps (4)-(5) can be repeated several times, each time the substrate is moved to focus the laser beam on different positions of the grating structure, and then several different cycles are obtained. Therefore, it can be used to detect the quality of the grating structure at different locations on the same substrate.

In order to make the grating detection device and the detection method of the present invention more clear, and to verify the measurement accuracy of the grating detection device of the present invention, please refer to the following experimental results.

Please refer to FIGS. 2 to 4, which show the grating structures of different gradation period intervals, respectively, the measurement results of the grating detection device, scanning electron microscope (SEM) and atomic force microscope (AFM) of the present invention. As shown in Figures 2 to 4, regardless of the period change, the grating detection device of the present invention has an accuracy close to that of SEM compared to AFM, even in the period of 209 nm to 233 nm (Figure 4). Under the gradual change period, the difference between it and AFM is greater, which also shows that the grating detection device of the present invention can not only quickly scan the grating structure of different cycle ranges, but also has a high level of accuracy, which is very suitable for application on large-sized substrates Raster detection.

In the above experiment, the laser beam has a wavelength of 355 nm, and the vertical height between the position where the light detector captures the diffracted light and the object carrier 2 is 147 mm, and the incident light of the laser beam The angle is 65 degrees. The single-point measurement time of the diffraction system is set to 0.6 seconds, but it is not limited to this. The measurement time is affected by the communication time between the computer (ie, data processor) and the grating detection device. The faster the communication speed, the shorter the single-point measurement time can be set, so that the scanning time required for the grating structure on the entire substrate (wafer) is shorter and more efficient. In addition, the measurable grating period range is 190~1000nm. This range is limited by the wavelength of the laser beam used. The use of different wavelengths can determine the measurement range of the grating period. Therefore, more than one Single-wavelength laser light source for grating measurement with a larger period range. The accuracy of the grating period measured by the diffraction system in this case is plus or minus 0.1 nm or better.

In contrast, using a scanning electron microscope or an atomic force microscope to measure the structural characteristics of the grating mainly uses electron beams or probes to scan out the grating pattern in a local area, and then manually pulls the grating pattern to extract the grating period and Fill factor, taking the measurement of grating structure with sub-micron grating period as an example, both methods can only parse out the grating pattern under the grating area of about 5x5μm in a single measurement, and then manually pull out the grating parameters. Therefore, it is not possible to quickly and efficiently detect large-area grating structures. Regarding the extraction of grating parameters, the manual pulling wire will cause a slight error, which is especially obvious in the measurement of the grating period using an atomic force microscope. Therefore, under the gradual change period (Figures 2 to 4), the atomic force The grating period data measured by the microscope clearly deviates from the other two methods.

Although the present invention has been disclosed in preferred embodiments, it is not intended to limit the present invention. Anyone who is familiar with this skill can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall be as defined in the scope of the attached patent application.

1‧‧‧ First slide

2‧‧‧Test object carrier

3‧‧‧ substrate

4‧‧‧Laser light source

5‧‧‧Light detector

6‧‧‧Second Slide

Li‧‧‧Laser beam

Df‧‧‧diffracted light

h‧‧‧Vertical height

x‧‧‧Horizontal distance

θi‧‧‧incidence angle

Claims (10)

A grating detection device includes: a test object carrier, which is horizontally and movably arranged on a first slide rail, the first slide rail is a two-dimensional slide rail for carrying a substrate, wherein the substrate has A grating structure; a laser light source, which is arranged above the object to be tested, to provide a laser beam, wherein the laser beam has a wavelength, and is incident on the substrate at an incident angle; a light detection The detector is movably and rotatably arranged on a second slide rail for capturing a diffracted light emitted from the substrate, wherein the second slide rail and the first slide rail are parallel to each other; and a data processor , Connected to the light detector, used to calculate and output a period of the grating structure; wherein the period is calculated by the following formula (I):

Where Λ represents the period, λ represents the wavelength of the laser beam, θi represents the angle of incidence, and x is a level between the position where the light detector captures the diffracted light and the object carrier The distance, and h is a vertical height between the position where the light detector captures the diffracted light and the object carrier. The grating detection device as described in item 1 of the patent application range, wherein the light detector is a position sensing device. A grating detection device as described in item 1 of the patent application range, wherein an angle at which the diffracted light enters the photodetector is equal to or approximately equal to 90 degrees. The grating detection device as described in item 1 of the patent application range, wherein the data processor calculates a diffraction efficiency of the diffracted light, which is divided by an energy of the diffracted light received by the photodetector With the light energy of the laser beam. The grating detection device as described in item 1 of the patent application scope further includes a beam expander for adjusting a diameter of the laser beam and focusing the laser beam on the substrate. A grating detection method includes the steps of: providing a substrate, wherein the substrate has a grating structure; placing the substrate on a test object carrier, wherein the test object carrier is horizontally and movably arranged on a first On the slide rail, the first slide rail is a two-dimensional slide rail; a laser beam is incident on the substrate at an angle of incidence, wherein the laser beam has a wavelength; a photodetector is used to capture the slave A diffracted light emitted, wherein the light detector is movably and rotatably disposed on a second slide rail, the first slide rail and the second slide rail are parallel to each other; and a data processor is used for calculation and output A period of the grating structure; wherein the period is calculated by the following formula (I):

Where Λ represents the period, λ represents the wavelength of the laser beam, θi represents the angle of incidence, and x is a level between the position where the light detector captures the diffracted light and the object carrier The distance, and h is a vertical height between the position where the light detector captures the diffracted light and the object carrier. The grating detection method as described in item 6 of the patent application scope, wherein the light detector is a position sensing device. The grating detection method as described in item 6 of the patent application range, wherein an angle at which the diffracted light enters the photodetector is equal to or approximately equal to 90 degrees. The grating detection method as described in item 6 of the patent application scope, wherein the step (5) further includes a step: calculating a diffraction efficiency of the diffracted light, wherein the diffraction efficiency is the value received by the light detector An energy of the diffracted light is divided by an outgoing light energy of the laser beam. According to the grating detection method described in item 6 of the patent application scope, before the laser beam is incident on the substrate, it also includes using a beam expander to adjust a diameter of the laser beam to focus the laser beam on the substrate .

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