TWI667448B - Inspecting device of gratings and inspecting method of same - Google Patents

Abstract

The invention provides a grating detecting device and a detecting method thereof. The grating detecting device comprises a test object carrier, horizontally movably disposed on a first sliding rail for carrying a substrate, wherein the substrate has a grating structure; a laser light source is disposed on the object to be tested Above the stage, a laser beam is provided, wherein the laser beam has a wavelength and is incident on the substrate at an incident angle; a photodetector is movably and rotatably disposed on a second slide a track 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 coupled to the photodetector for calculation and output One cycle of the grating structure. The detection method uses the grating detecting device to obtain the period of the grating structure.

Description

Grating detecting device and detecting method thereof

The present invention relates to a grating detecting device and a detecting method thereof, and more particularly to a diffracted light emitted by detecting a grating structure, obtaining a period of the grating structure from the position of the diffracted light, and further detecting the grating A grating detecting device with uniformity of structure and a detecting method thereof.

After the laser strikes the grating at a specific angle, in addition to the reflected light of the same angle of incidence, at least one diffracted light appears in accordance with the grating period, material, and environmental refractive index. In general, after measuring the diffraction angle of the diffracted light, the grating period can be known by the formula, and the intensity of the diffracted light can reflect the grating quality.

The characteristics of the grating elements are affected by many factors, and the conditions are mainly determined by the period, the filling factor and the thickness, regardless of the material absorption conditions. In the detection, the surface structure and the high and low undulations are often measured by scanning electron microscopy (SEM) or atomic force microscopy (AFM), and the grating characteristics are judged by detecting the period, thickness and filling factor; or by the diffraction system. The grating characteristic uses the detection of the diffraction efficiency and the period as the reference coefficient of the grating, but the morphology of the surface or side of the grating cannot be actually observed. Therefore, the grating quality can be judged by the SEM or AFM and the diffraction system, respectively. However, the currently known diffraction system architecture cannot be fast and large The grating detection of the product has no advantage compared with the scanning electron microscope or the atomic force microscope.

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 detecting device and a detecting method thereof, which utilize a horizontally moving object to-be-tested object and a rotatable and movable photodetector to improve the accuracy of detection. Since the angle at which the laser light is incident on the stage of the object to be tested is fixed during the detection process, different diffracted light is emitted according to the different periodic grating structures of the substrate to be tested on the object to be tested. The grating detecting device of the invention can determine the grating period by using the moving distance of the photodetector, the vertical height of the photodetector and the incident angle, and has the advantages of simple structure, fast detection speed and high precision.

In order to achieve the above object, an embodiment of the present invention provides a grating detecting device, comprising: a to-be-measured object, which is horizontally movably disposed on a first sliding rail, wherein the first sliding rail is a two-dimensional a slide rail for carrying a substrate, wherein the substrate has a grating structure; a laser light source is disposed above the object carrier to provide a laser beam, wherein the laser beam has a wavelength, and An incident light is incident on the substrate; a photodetector is movably and rotatably disposed on a second slide rail for capturing a diffracted light emitted from the substrate, wherein the second slide rail The first slide rails are parallel to each other; and a data processor is coupled to the photodetector for calculating and outputting 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 at which the photodetector captures the diffracted light and the stage of the object to be tested The distance, and h is a vertical height between the position at which the photodetector 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, the angle at which the diffracted light enters the photodetector is equal to or substantially 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 photodetector 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.

Another embodiment of the present invention provides a grating detecting method, including the steps of: providing a substrate, wherein the substrate has a grating structure; placing the substrate on a to-be-tested object stage, wherein the object to be tested is horizontally Movably disposed on a first sliding rail, the first sliding rail is a two-dimensional sliding rail; and a laser beam is incident on the substrate at an incident angle, wherein the laser beam has a wavelength; The photodetector captures a diffracted light emitted from the substrate, wherein the photodetector is movably and rotatably disposed on a second slide rail, the first slide rail and the second slide rail being parallel to each other; 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 at which the photodetector captures the diffracted light and the stage of the object to be tested The distance, and h is a vertical height between the position at which the photodetector 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, the angle at which the diffracted light enters the photodetector is equal to or substantially equal to 90 degrees.

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

In an embodiment of the invention, before the laser beam is incident on the substrate, a beam expander is used to adjust a diameter of the laser beam to focus the laser beam on the substrate.

1‧‧‧First slide rail

2‧‧‧Test object carrier

3‧‧‧Substrate

4‧‧‧Laser light source

5‧‧‧Photodetector

6‧‧‧Second rail

Li‧‧‧Laser beam

Df‧‧‧Diffraction

H‧‧‧vertical height

X‧‧‧ horizontal distance

Θi‧‧‧ incident angle

Fig. 1 is a schematic view showing a grating detecting device according to an embodiment of the present invention.

Fig. 2 is a view showing measurement results of a grating structure having a gradation period of 381 nm to 612 nm, respectively, using the grating detecting device, scanning microscope (SEM) and atomic force microscope (AFM) of the present invention.

Fig. 3 is a view showing measurement results of a grating structure having a gradation period of 263 nm to 337 nm, respectively, using the grating detecting device, scanning microscope (SEM) and atomic force microscope (AFM) of the present invention.

Fig. 4 is a view showing measurement results of a grating structure having a gradation period of 209 nm to 233 nm, respectively, using the grating detecting device, scanning microscope (SEM) and atomic force microscope (AFM) of the present invention.

The above and other objects, features and advantages of the present invention will become more <RTIgt; Furthermore, the directional terms mentioned in the present invention, such as upper, lower, top, bottom, front, rear, left, right, inner, outer, side, surrounding, central, horizontal, horizontal, vertical, longitudinal, axial, Radial, uppermost or lowermost, etc., only refer to the direction of the additional schema. In addition, the singular forms "a", "the" The range of values (such as 10% to 11% of A) includes upper and lower limits (ie, 10% ≦A ≦ 11%) unless otherwise specified; if the value range does not define a lower limit (such as less than 0.2% B) , or B) below 0.2%, the lower limit may be 0 (ie 0% ≦ B ≦ 0.2%). The above terms are used to illustrate and understand the present invention and are not intended to limit the invention.

In order to measure the grating period and the diffraction intensity quickly and accurately, please refer to FIG. 1 , a grating detecting device according to an embodiment of the present invention, which mainly comprises: a to-be-measured object stage 2 , which is horizontally movably disposed on a first slide rail 1 for carrying a substrate 3, wherein the substrate 3 has a grating structure; a laser light source 4 is disposed above the object carrier 2 for providing 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 sliding rail 6 and the first sliding rail 1 are parallel to each other; and a data processor (not shown) connected to the photodetector 5 for calculating And outputting 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 at which the photodetector 5 complements the diffracted light Df and A horizontal distance between the measuring stage 2, and h is a vertical height between the position where the photodetector 5 captures the diffracted light Df and the object holding stage 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 having a period of 200 to 300 nm.

Preferably, the laser source 4 can be a solid-state laser, but is not limited thereto, and can be adjusted according to a required detection period range. Generally, the minimum detectable period is the wavelength of the laser beam. 0.5 times. In an embodiment of the invention, the photodetector 5 is preferably a position sensitive device (PSD) capable of automatically tracking the position at which the intensity of the diffracted light is maximum, so that the data processor can be used to obtain the light. The displacement distance x of the detector 5 and the angle of rotation. Preferably, the angle of the diffracted light Df entering the photodetector 5 is equal to or substantially equal to 90 degrees, so that the position at which the diffracted light is received for each measurement is substantially the maximum diffracted light intensity to reduce the measurement error. Preferably, the data processor can also be used to calculate the A diffraction efficiency of the diffracted light, the diffraction efficiency being an energy of the diffracted light received by the photodetector divided by an outgoing light energy of the laser beam. In addition, in an embodiment of the present invention, a beam expander may be further disposed between the laser light source 4 and the object carrier 2, and the diameter of the laser beam may be adjusted. The laser beam Li is focused on the substrate 3 of the object carrier 2 to be tested.

According to the grating detecting device of the present invention, the first slide rail 1, the second slide rail 6, and the photodetector 5 can be utilized to achieve a position that can move and rotatably capture the diffracted light, and control the winding The angle of the incident light incident on the photodetector 5 is close to vertical, and is matched with the to-be-measured object stage 2 which can be horizontally moved. Since the substrate 3 is driven by the to-be-measured object stage 2, the horizontal direction can be performed. Two-dimensional displacement (that is, the substrate 3 can be maintained to move on a plane), so that a fast multi-point scan can be performed at a fixed incident angle, and the grating period and diffraction efficiency of the substrate 3 can be obtained by calculation. The rapid and accurate detection of the uniformity of the large-area grating structure is greatly different from the conventional one using a scanning electron microscope or an atomic force microscope to detect only a small-scale grating structure and taking a long time.

Please refer to FIG. 1 , another embodiment of the present invention provides a grating detecting method, comprising the steps of: (1) providing a substrate 3 , wherein the substrate 3 has a grating structure; and (2) placing the substrate 3 in a On the object to be tested 2; (3) a laser beam Li is incident on the substrate 3 at an incident angle; (4) using a photodetector 5 to capture a diffracted light Df emerging from the substrate 3; And (5) calculating and outputting a period of the grating structure using a data processor. The following describes each step in detail.

In the grating detecting method, firstly, (1) a substrate 3 is provided, wherein the substrate 3 has a grating structure. In this step, the substrate 3 is used as a sample to be tested, and the grating junction The structure may have a one-dimensional periodic structure or a two-dimensional periodic structure.

In the grating detecting method, the following is: (2) placing the substrate 3 on a to-be-measured object stage 2. In this step, the DST platform 2 is horizontally movably disposed on a first slide rail 1. That is to say, the test object stage 2 performs only two-dimensional horizontal displacement without performing any rotation or angle changing behavior.

In the grating detecting 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 source 4, which may for example be a solid-state laser source, but is not limited thereto.

In the grating detecting method, the following is: (4) capturing a diffracted light emitted from the substrate 3 using a photodetector 5. In this step, the photodetector 5 is movably and rotatably disposed on a second slide rail 6, and the first slide rail 1 and the second slide rail 6 are parallel to each other. That is to say, the photodetector 5 can be horizontally moved and can be rotated to change the angle to facilitate receiving the diffracted light. Preferably, the angle of the diffracted light Df entering the photodetector 5 is equal to or substantially equal to 90 degrees, so that the position at which the diffracted light is received for each measurement is substantially the maximum diffracted light intensity to reduce the measurement error. .

In the raster detection method, the following is: (5) calculating and outputting a period of the grating structure using a data processor, 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 at which the photodetector captures the diffracted light and the object to be tested a horizontal distance between the stations 2, and h is the position at which the photodetector captures the diffracted light A vertical height between the test object stage 2 and the object.

In an embodiment of the invention, the step (5) further comprises the step of: calculating a diffraction efficiency of the diffracted light Df, wherein the diffraction efficiency is the diffracted light Df received by the photodetector 5 One energy is divided by the light energy of the laser beam Li. The light exiting energy refers to the initial energy of the laser beam Li 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) capable of automatically tracking the position of the intensity of the diffracted light, so that the photodetector can be used to obtain the photodetector. The displacement distance x of 5 and the angle of rotation. The data processor can be, for example, a computer host that uses an automated calculation or detection program to confirm the location at which the photodetector 5 captures the diffracted light.

Preferably, the above steps (4)-(5) can be repeated several times, each time the substrate is moved to focus the laser beam at different positions of the grating structure, and then several different periods. Therefore, it is possible to apply the quality of the grating structure for detecting different portions on the same substrate.

In order to clarify the grating detecting device and the detecting method of the present invention and verify the measurement accuracy of the grating detecting device of the present invention, please refer to the following experimental results.

Please refer to Figures 2 to 4, which show the grating structures of different gradation period intervals, respectively, using the grating detecting device, scanning electron microscope (SEM) and atomic force microscope (AFM) of the present invention. As shown in Figures 2 to 4, the grating detecting device of the present invention has an accuracy closer to that of the SEM than the AFM regardless of the period change, even in the period of 209 nm to 233 nm (Fig. 4). Under the gradual cycle, the difference between AFM and AFM is greater, also said It is understood that the grating detecting device of the invention can not only quickly scan grating structures of different period ranges, but also has a high level of precision, and is very suitable for grating detection applied on large-sized substrates.

In the above experiment, the laser beam has a wavelength of 355 nm, and a vertical height between the position where the photodetector captures the diffracted light and the object carrier 2 is 147 mm, and the incident light of the laser beam is incident. The angle is 65 degrees. The single point measurement time of the diffraction system is set to 0.6 seconds, but is not limited thereto, and the measurement time is affected by the communication time between the computer (ie, the data processor) and the grating detecting device, if between The faster the communication speed, the shorter the single point measurement time can be set, so that the grating structure on the entire substrate (wafer) requires shorter scan time and is more efficient. In addition, the measurable grating period ranges from 190 to 1000 nm. This range is limited by the wavelength of the laser beam used. Different wavelengths can be used to determine the measurement range of the grating period. Therefore, more than one unit can be integrated. Single-wavelength laser source for grating measurement over a larger period of time. The accuracy of the grating period measured by the diffraction system of the present invention 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, the grating pattern of the local region is mainly scanned by an electron beam or a probe, and the grating period is extracted by pulling the wire on the grating pattern manually. The filling factor is used to measure the grating structure with the sub-micron grating period. In both cases, the grating pattern can be resolved only under the grating area of about 5×5 μm in a single measurement, and the grating parameters can be extracted manually. Therefore, the detection of a large-area grating structure cannot be performed quickly and efficiently. In terms of the extraction of the grating parameters, the slight error caused by the manual pulling of the wire is especially obvious in the period of measuring the grating by the atomic force microscope, so in the gradual period of (Fig. 2 to 4), the atomic force The grating period data measured by the microscope is significantly deviated from the other two methods.

The present invention has been disclosed in its preferred embodiments, and is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

Claims (9)

A grating detecting device, comprising: a to-be-tested object stage, horizontally movably disposed on a first sliding rail, wherein the first sliding rail is a two-dimensional sliding rail for carrying a substrate, wherein the substrate has a grating structure; a laser light source disposed above the object carrier for providing a laser beam, wherein the laser beam has a wavelength and is incident on the substrate at an incident angle; a detector movably and rotatably disposed 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 And connecting to the photodetector for calculating and outputting 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, θ i represents the angle of incidence, and x is a position between the position where the photodetector captures the diffracted light and the stage of the object to be tested The horizontal distance, and h is a vertical height between the position at which the photodetector captures the diffracted light and the object carrier. The grating detecting device of claim 1, wherein the photodetector is a position sensing device. The grating detecting device of claim 1, wherein the diffraction An angle of light entering the photodetector is equal to or substantially equal to 90 degrees. The grating detecting device of claim 1, wherein the data processor calculates a diffraction efficiency of the diffracted light, the diffraction efficiency being an energy removal of the diffracted light received by the photodetector A light energy of the laser beam. A grating detecting method, comprising the steps of: providing a substrate, wherein the substrate has a grating structure; placing the substrate on a to-be-tested object stage, wherein the to-be-measured object stage is horizontally movably disposed at 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 incident angle, wherein the laser beam has a wavelength; and a photodetector is used to capture the substrate a diffracted light, wherein the photodetector 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, θ i represents the angle of incidence, and x is a position between the position where the photodetector captures the diffracted light and the stage of the object to be tested The horizontal distance, and h is a vertical height between the position at which the photodetector captures the diffracted light and the object carrier. The grating detection method of claim 5, wherein the optical detection The detector is a position sensing device. The grating detecting method of claim 5, wherein an angle at which the diffracted light enters the photodetector is equal to or substantially equal to 90 degrees. The grating detecting method according to claim 5, wherein the step (5) further comprises a step of: calculating a diffraction efficiency of the diffracted light, wherein the diffraction efficiency is received by the photodetector An energy of the diffracted light is divided by an outgoing light energy of the laser beam. The grating detecting method of claim 5, before the laser beam is incident on the substrate, further comprising the step of adjusting a diameter of the laser beam to focus the laser beam on the substrate.