KR19990066595A - Mask inspection device and mask inspection method - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mask inspection apparatus and a method for inspecting a mask thereof, the method comprising: a mask inspection apparatus using a mask inspection apparatus for detecting defects on a mask substrate and a mask pattern using light sources, beam splitters, detectors, and polarizers. A beam splitter is used to split the beam generated from the light source into a first beam and a second beam. The polarity of the first beam and the second beam is changed using the first polarizer and the second polarizer, respectively. The first beam is incident on the mask pattern, and the second beam collected through the first lens is incident on the mask substrate. The first and second lenses are used to condense the first beam reflected from the mask pattern and the second beam passing through the mask substrate. Only the first beam focused through the first lens is passed using the third polarizer. The first detector and the second detector are used to read the first beam and the second beam, respectively. By using such a mask inspection apparatus and a mask inspection method, defects on a mask pattern and a mask substrate can be detected by one inspection, respectively, thereby reducing the cost and time required for conventional mask inspection.

Description

APAPATUS OF DETECTING MASK DEFFECT AND METHOD OF DETECTING MASK DEFFECT WITH THE SAME

The present invention relates to a mask inspection apparatus and a mask inspection method thereof. More specifically, the present invention relates to a mask inspection apparatus including a hard defect inspection method using transmitted light and a soft defect inspection using light scattering, and a method for inspecting the same.

Conventional mask inspection methods can be broadly classified into two types. The first detects pinholes, spots, and extensions of a mask by comparing die to die, die to database, and mask to mask. The second method is a hard defect inspection method, and a second method is a soft defect inspection method in which defects are detected by scattering beams reflected on a mask of particles and droplets on a mask. However, since the hard defect inspection method is a method of detecting mask defects by comparing the same die or the same mask, the soft defect cannot be detected, and the soft defect inspection method is a method of inspecting the entire surface of the mask using a beam. Therefore, hard defects cannot be detected.

1 is a view showing a conventional mask inspection apparatus.

Referring to FIG. 1, a conventional mask inspection apparatus transmits a light source LS that generates a beam, a first lens L1 that collects the beam B, and enters the mask M, and the mask M. FIG. The second lens L2 condenses one beam, and the detector DT detects a defect of the mask M from the condensed beam B. In the hard defect inspection method according to the related art, the first lens L1 causes the beam B generated by the light source LS to enter the mask M vertically. The second lens L2 condenses the beam B transmitted through the mask.

The detector DT converts the focused beam into a digital signal using an A / D converter, and reconstructs an image by performing the image processing process on the digital signal. The hard defect was detected by comparing the same die with information on the shape of the mask extracted from the reconstructed image.

However, such a conventional hard defect inspection method uses only a beam incident in a direction perpendicular to the mask, and thus softly detects impurities on the mask pattern because the beam does not pass through the Cr film of the mask, that is, the mask pattern. There is a problem that can't check defect.

The present invention has been proposed to solve the above-mentioned problems, and an object thereof is to provide a mask inspection apparatus and an inspection method thereof capable of simultaneously performing a hard defect inspection and a soft defect inspection of a mask.

1 is a view showing the structure of a conventional mask inspection apparatus;

2 shows a mask inspection apparatus according to an embodiment of the present invention;

3A to 3C show a path of a beam reflected from a mask pattern using a mask inspection apparatus according to an embodiment of the present invention;

* Explanation of symbols for the main parts of the drawings

B1, B2: Beam BS1, BS2: Beam Separator

PL1-PL3: polarizer M1, M2: mirror

L1, L2: Lens DT1, DT2: Detector

LS: Light source MS: Mask substrate

MP: mask pattern

(Configuration)

According to a feature of the present invention proposed to achieve the above object, a mask inspection apparatus for detecting defects on a mask substrate and a mask pattern using a light source is to separate the beam generated from the light source into a first beam and a second beam. A first beam splitter; A first mirror for redirecting the first beam toward the mask; A first polarizer for changing the polarity of the redirected first beam; A second mirror for injecting the first beam having a changed polarity into a mask pattern; A first lens for focusing the first beam reflected from the mask pattern; A second polarizer for passing only the focused first beam; A first detector reading the first beam passing through the second polarizer to detect a defect on a mask pattern; A third polarizer for changing the polarity of the second beam; A second beam splitter for separating the first beam focused through the first lens and the second beam having a changed polarity; A second lens, which is separated through the second beam splitter, is collected through the first lens and is incident on a mask substrate, and collects a second beam that has passed through the mask substrate; And a second detector for reading a second beam focused through the second lens to detect a defect on the mask substrate.

In a preferred embodiment of the apparatus, the first polarizer and the second polarizer cause the first beam and the second beam to have a phase difference of 90 degrees.

In a preferred embodiment of the device, the first mirror causes the first beam to enter the mask pattern at an acute angle.

According to another feature of the present invention proposed to achieve the above object, a mask inspection using a mask inspection apparatus for detecting defects on a mask substrate and a mask pattern using a light source, a beam splitter, two detectors, and three polarizers The method includes separating a beam from the light source into a first beam and a second beam using the beam splitter; Varying the polarity of the first beam and the second beam using the first polarizer and the second polarizer, respectively; Incident the first beam onto a mask pattern and incident a second beam focused through the first lens onto a mask substrate; Condensing the first beam reflected from the mask pattern and the second beam transmitted through the mask substrate using the first lens and the second lens; Passing only the first beam focused through the first lens using the third polarizer; Detecting defects on the mask pattern and the mask substrate by reading the first beam and the second beam, respectively, using the first detector and the second detector.

In a preferred embodiment of this method, the first beam and the second beam of which polarity is changed are such that they have a phase difference of 90 °.

In a preferred embodiment of the method, the first beam incident on the mask pattern is incident at an acute angle on the mask pattern.

(Action)

Defects on the substrate of the mask are detected and defects of the mask pattern are detected.

(Example)

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 2 and 3.

2 is a view showing a mask inspection apparatus according to an embodiment of the present invention, Figures 3a to 3c is a view showing the path of the beam reflected from the mask pattern using the mask inspection apparatus according to an embodiment of the present invention.

In FIG. 2, a mask inspection apparatus for detecting defects of a mask M having a mask substrate MS and a mask pattern MP using a light source according to an exemplary embodiment of the present invention may detect a beam generated by the light source LS. It includes a first beam splitter (BS1) for separating into a first beam (B1) and a second beam (B2). It includes a first mirror (M1) for changing the direction of the first beam (B1) to the mask (M). It includes a first polarizer (PL1) for changing the polarity of the first beam (B1). It includes a second mirror (M1) for injecting the first beam (B1) to the mask pattern (MP). In this case, the first beam is incident with an acute angle with the mask pattern. The first lens L1 collects the first beam B1 reflected by the mask pattern MP. And a second polarizer PL3 that separates only the first beam B1 beam collected through the first lens. The first detector DT1 detects a defect of the mask pattern MP from the first beam B1. And a third polarizer PL2 for changing the polarity of the second beam B2. It includes a second beam splitter (BS2) for separating the first beam (B1) and the second beam (B2). The first lens L1 collects the two beams B2 and enters the mask substrate MS perpendicularly. The second lens L2 collects the second beam B2 passing through the mask substrate MS. The second detector DT2 detects a defect of the mask substrate MS from the second beam B2.

According to an embodiment of the present invention, the light source LS, two mirrors M1 and M2, two beam splitters BS1 and BS2, two detectors DT1 and DT2, three polarizers PL1, The mask inspection method using the mask inspection apparatus which detects the defect of the mask M which has the mask substrate MS and the mask pattern MP using PL2 and PL3 is as follows. The beam from the light source LS is separated into a first beam B1 and a second beam B2 using the first beam splitter BS1. The path of the first beam B1 is changed using the first mirror M1. The polarity of the first beam B1 is changed by using the first polarizer PL1 so as to have a phase difference of 90 ° with the second beam B2. The first beam B1 is incident on the mask pattern MP of the mask M at an acute angle using the second mirror M2.

3A to 3B, the first beam B1 reflected by the mask pattern MP is reflected at a predetermined angle with the constant mask pattern MP, and is reflected from impurities P on the mask pattern MP. The reflected first beam B1 scatters at various angles with the mask pattern MP.

The polarity of the second beam B2 is changed by using the second polarizer PL2. The first beam B1 reflected by the mask pattern MP is collected using the first lens L1, and the second beam BS2 is collected by the second beam splitter BS2 to collect a mask. Incident to M). In this case, the second beam is incident in a direction perpendicular to the mask to transmit only the mask substrate MS.

Referring to FIG. 3C, the reflection of the impurity P of the first beam B1 incident at an acute angle with the second beam B2 incident in the vertical direction to the mask pattern MP is illustrated.

The second beam splitter BS2 separates the first beam B1 condensed by the first lens L1 and the second beam B2 through the second polarizer PL2. Only the first beam B1 focused by the first lens L1 is separated using the third polarizer PL3. The second lens L2 collects the second beam B2 from the first lens L1 that has passed through the mask substrate MS of the mask M.

Defects of the mask pattern MP are detected from the first beam B1 using the first detector DT1. Defects of the mask substrate MS are detected from the second beam B2 using the second detector DT2.

The present invention solves the problem that the hard defect and the soft defect of the conventional mask inspection apparatus and its mask inspection method cannot be detected at the same time, and has an acute angle to the mask substrate and the mask using a beam incident perpendicularly to the mask. Simultaneously detecting defects in a mask pattern using a beam to reduce the cost and time required for conventional mask inspection.

Claims (6)

In the mask inspection apparatus which detects the defect of the mask M which has the mask substrate MS and the mask pattern MP using the light source LS, A first beam splitter (BS1) for separating the beam generated from the light source (LS) into a first beam (B1) and a second beam (B2); A first mirror M1 which redirects the first beam B1 toward the mask M; A first polarizer (PL1) for changing the polarity of the first beam (B1) which has been changed in direction; A second mirror M1 for injecting the first beam B1 having a changed polarity into the mask pattern MP; A first lens L1 condensing the first beam B1 reflected from the mask pattern MP; A second polarizer (PL3) for passing only the focused first beam (B1); A first detector (DT1) for detecting a defect on a mask pattern (MP) by reading the first beam (B1) passed through the second polarizer; A third polarizer (PL2) for changing the polarity of the second beam (B2); A second beam splitter (BS2) for separating the first beam (B1) collected through the first lens and the second beam (B2) whose polarity is changed; The second beam B2 separated by the second beam splitter is collected through the first lens L1 and incident on the mask substrate MS. A second lens L2 for condensing the second beam B2 passing through the mask substrate MS; And a second detector (DT2) for detecting a defect on the mask substrate (MS) by reading the second beam (B2) collected through the second lens. The method of claim 1, And the first polarizer and the second polarizer are configured such that the first beam and the second beam have a phase difference of 90 degrees. The method of claim 1, And the first mirror allows the first beam to enter the mask pattern at an acute angle. Mask substrate MS using light source LS, beam splitter BS, first and second detectors DT1 and DT2, first and second and third polarizers PL1, PL2, PL3 and In the mask inspection method using a mask inspection apparatus for detecting a defect on the mask pattern (MP), Separating the beam from the light source (LS) into a first beam (B1) and a second beam (B2) using the beam splitter (BS); Changing the polarity of the first beam (B1) and the second beam (B2) using the first polarizer (PL1) and the second polarizer (PL2), respectively; Injecting the first beam B1 into the mask pattern MP and injecting the second beam B2 collected through the first lens into the mask substrate MS; Condensing the first beam B1 reflected from the mask pattern MP and the second beam B2 transmitted through the mask substrate MS using the first lens L1 and the second lens L2. Making a step; Passing only the first beam (B1) focused through the first lens (L1) using the third polarizer (PL3); Defects on the mask pattern MP and the mask substrate MS by reading the first beam B1 and the second beam B2 using the first detector DT1 and the second detector DT2, respectively. Mask inspection method comprising the step of detecting each. The method of claim 4, wherein The first beam and the second beam having a changed polarity has a phase difference of 90 °. The method of claim 4, wherein The first beam (B1) incident on the mask pattern MP is incident to the mask pattern (MP) at an acute angle.