KR20210016106A - System for Detecting Error in Semiconductor Device - Google Patents

Abstract

The present invention relates to a technology related to a defect detecting system of a semiconductor device. According to an embodiment of the present invention, the defect detecting system comprises a measurement device and a computer device. The measurement device includes: a first optical unit for irradiating incident light to an object to be measured; a second optical unit for condensing reflected light reflected from the object to be measured; and a detection unit for outputting light output from the second optical unit as measurement image data. The second optical unit includes a Sagnac interferometer for causing interference by advancing the reflected light in a direction facing each other on at least one optical path. In addition, a dove prism for rotating the reflected light at a predetermined angle to emit the same at the optical path is provided. Accordingly, a defect of a deep unit of the semiconductor device can be easily detected.

Description

System for Detecting Error in Semiconductor Device {System for Detecting Error in Semiconductor Device}

It relates to a semiconductor manufacturing system, and more specifically, to a defect detection system of a semiconductor device.

In order to determine the good/defective of a semiconductor device, various measurement methods have been proposed. Currently, non-contact non-destructive measuring equipment has been proposed without direct contact or processing with the pattern.

On the other hand, as the integration density of semiconductor devices increases, the size and shape of patterns become very fine and complex. Accordingly, measurement equipment needs to detect not only surface defects but also defects in depth.

Defects of the deep part may include, for example, an overlay failure of a deep contact hole, a tilt failure, or a polygon failure of a contact plug. Since it is difficult to accurately determine the above-described defects of the deep-layer part only by the defect detection method of the upper surface part of the resultant semiconductor substrate, defects in the deep-layer part are inspected using complex and various optical elements.

Embodiments of the present invention provide a semiconductor device defect detection system capable of easily detecting a defect in a deep portion of a semiconductor device without the need for complex optical devices.

A semiconductor defect detection system according to an embodiment of the present invention includes: a first optical unit for irradiating incident light onto an object to be measured; A second optical unit for condensing reflected light reflected from the measurement object; And a measurement device including a detection unit that outputs the light output from the second optical unit as measurement image data. The second optical unit includes a Sanak interferometer for causing interference by propagating the reflected light in a direction facing each other on at least one optical path. A dove prism is further provided on the at least one optical path of the Sanak interferometer to rotate the reflected light at a predetermined angle to emit it.

A semiconductor defect detection system according to an embodiment of the present invention includes: a first optical unit including at least one optical medium for irradiating incident light onto a measurement object; An interferometer configured to receive reflected light having the same directionality reflected from the measurement object, divide, rotate, and interfere with the reflected light to output the interference light; A detection unit that generates measurement image data of the interfering light; And a computer device that receives measurement image data of the interference light and determines a defect in the measurement object.

The interferometer includes first to third mirrors and half mirrors that are sequentially arranged to form a closed curve-shaped optical path; And a dove prism disposed in one of the half mirrors and an optical path between the first and third mirrors disposed adjacent thereto.

The half mirror is configured to receive the reflected light to provide a first reflected light toward the first mirror and to provide a second reflected light toward the third mirror.

The dove prism is disposed so that its longitudinal direction and the optical path are parallel, and the dove prism rotates the first reflected light incident through one end thereof at a predetermined angle and outputs it to the other end. It is configured to rotate the second reflected light incident through the other end and output it to one end of the dove prism.

The interferometer is configured to output an interference result of the rotated first reflected light and the rotated second reflected light output from the dove prism as the interference light.

In the semiconductor device failure detection system according to the present embodiment, a Sanac interferometer having a dove prism is installed in its measuring device. Accordingly, various defects in the depth of the measurement object can be detected from the measurement image of the interference light obtained by rotation and interference of light reflected from the measurement object. Accordingly, since a plurality of rotating optical elements for modifying the reflected light and an operation block for extracting polarization phase information of the light are not required, manufacturing cost can be reduced.

1 is a block diagram schematically illustrating a system for detecting a defect in a semiconductor device according to an exemplary embodiment of the present invention.
FIG. 2 is a block diagram showing the measurement device of FIG. 1.
3 is a block diagram illustrating a process of transmitting reflected light according to an embodiment of the present invention.
4 is a diagram schematically showing a Sanac interferometer according to an embodiment of the present invention.
5 is a perspective view for explaining a dove prism according to an embodiment of the present invention.
6 is a cross-sectional view illustrating an example of an overlay defect and a tilt defect of a semiconductor device.
7 is a flowchart illustrating a method for determining a defect according to an embodiment of the present invention.

Advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms different from each other, and only these embodiments make the disclosure of the present invention complete, and common knowledge in the technical field to which the present invention pertains. It is provided to completely inform the scope of the invention to those who have it, and the invention is only defined by the scope of the claims. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity of description. The same reference numerals refer to the same components throughout the specification.

1 is a block diagram schematically illustrating a system for detecting a defect in a semiconductor device according to an exemplary embodiment of the present invention. FIG. 2 is a block diagram showing the measurement device of FIG. 1. 3 is a block diagram illustrating a process of transmitting reflected light according to an embodiment of the present invention.

Referring to FIG. 1, the system 10 for detecting a failure of a semiconductor device according to the present embodiment includes a measuring device 100 and a computing device 200.

The measurement device 100 irradiates light to the measurement object 20 to measure changes in intensity and phase, and measures various physical properties such as asymmetry, thickness, refractive index, and surface roughness of the measurement object as measurement image data. I can.

The computing device 200 is configured to determine a defect of the measurement object 20 and a type of defect from the measurement image data of the measurement device 100. The computing device 200 may include a processor 210 and a storage unit 220.

As shown in FIG. 2, the measuring device 100 according to the present embodiment may include a first optical unit IP, a second optical unit RP, and a detection unit 140.

The first optical unit IP is a block for irradiating light onto the measurement object 20 provided with the pattern 21. The first optical unit IP may include a light source 112, a polarizer 114, a first radial polarizer 116, a beam splitter 118, and an objective lens 120. .

First, the light source 112 may provide incident light L1 to the measurement object 20. The light source 112 may use infrared rays that provide parallel light, but is not limited thereto. Since the degree of reaction according to the optical interaction of the measurement object 20 varies according to the selected wavelength of the light source 112, the type of the light source 112 may be determined according to the pattern 21 and the intended use.

The polarizer 114 may change polarization characteristics of incident light provided from the light source 112. The polarizer 114 may include a polarization axis (not shown). For example, the polarizer 114 may selectively pass a TE mode (transverse electric mode) component of the incident light L1 and a transverse magnetic mode (TM) mode.

The first radiation polarizer 116 may change a polarization direction of incident light polarized by the polarizer 114. In addition, the radiation polarizer 116 may adjust the polarization of light incident with linearly polarized light to the TE mode or the TM mode. The beam splitter 118 changes the path of the incident light provided from the radiation polarizer 116 and transmits the incident light L1 to the objective lens 120 above the measurement object 20. The beam splitter 118 of the present embodiment may be, for example, a half mirror, and may have a function of reflecting or passing light.

The objective lens 120 condenses the incident light provided by the beam splitter 118 and irradiates the object to be inspected on the surface of the measurement object 20.

Although not shown in detail in FIG. 2, at least one optical element, such as a polarizer, may be additionally installed between the beam splitter 118 and the objective lens 120. In addition, although the first optical unit IP of the present embodiment has been described an example consisting of one polarizer 114, one radiation polarizer 116, one beam splitter 118, and the objective lens 120, The first optical unit IP is not limited thereto, and of course, the first optical unit IP may further include additional optical media.

The second optical unit RP may be configured to collect light (hereinafter, reflected light, L2) that is reflected and scattered from the surface and deep portions of the surface of the measurement object 20. The second optical unit RP includes the objective lens 120, the beam splitter 118, a Sagnac and interferometer 125, a second radiation polarizer 129, an analyzer 131, and a condensing lens. (133) may be included.

The objective lens 120 and the beam splitter 118 as the second optical unit RP serve to transmit the reflected light L2 reflected from the measurement object 20 to the Sanac interferometer 125. The objective lens 120 and the beam splitter 118 driven by the second optical unit RP may transmit light traveling in the same direction among the lights reflected from the measurement object 20 to the Sanac interferometer 125.

4 is a diagram schematically showing a Sanac interferometer according to an embodiment of the present invention.

Referring to FIG. 4, the Sanac interferometer 125 of the present embodiment may include a plurality of mirrors M1 to M3 and one half mirror (HM). The plurality of mirrors M1 to M3 and the half mirror HM may be sequentially disposed at predetermined intervals so that the optical paths generated therebetween have a closed curve shape. For example, a beam splitter may be used as the half mirror HM of the Sanac interferometer 125 of the present embodiment.

The reflected light L2 transmitted from the objective lens 120 and the beam splitter 118 is transmitted to the half mirror HM of the Sanac interferometer 125. The half mirror HM divides the reflected light L2 into a first reflected light L2_1 and a second reflected light L2_2, and provides the first reflected light L2_1 to the first mirror M1, and the second reflected light (L2_2) is provided to the second mirror M2.

The first reflected light L2_1 may be transmitted through paths of the first mirror M1, the second mirror M2, the third mirror M3, and the half mirror HM. Meanwhile, the second reflected light L2_2 is transmitted through paths of the third mirror M3, the second mirror M2, the first mirror M1, and the half mirror HM.

Accordingly, since the two reflected lights L2_1 and L2_2 traveling in opposite directions to each other are transmitted to the Sanac interferometer 125 for each optical path, interference may easily occur.

In addition, the Sanac interferometer 125 of the present embodiment may include a Dove prism 127 in any one of a plurality of optical paths. The dove prism 127 may be positioned between the half mirror HM and one of the mirrors adjacent to the half mirror HM, for example, the third mirror M3.

5 is a perspective view for explaining a dove prism according to an embodiment of the present invention.

Referring to FIG. 5, the dove prism 127 is a reflective prism having a trapezoidal shape in cross section. The dove prism 127 may be output by rotating the angle of the incident image arbitrarily.

The dove prism 127 is an optical element capable of observing a specific image while rotating by a predetermined angle with respect to the length axis d. For example, an image of incident light passing through the dove prism 127 may be displayed in a form that is rotated twice as much as the rotation angle of the dove prism 127.

The dove prism 127 of this embodiment is located on the optical path of the Sanac interferometer 125. For example, the dove prism 127 may be arranged such that its longitudinal direction and the optical path are parallel. Accordingly, the first reflected light L2_1 may be incident through the one end 127a of the dove prism 127 and the second reflected light L2_2 may be incident through the other end 127b.

The first reflected light L2_1 and the second reflected light L2_2 are incident through opposite ends 127a and 127b of the dove prism 127, and are emitted while being rotated by a predetermined angle in opposite directions. The first and second reflected light L2_1 and L2_2 passing through the dove prism 127 cause interference in the Sanac interferometer 125, and the interference result (hereinafter, interference light) is provided to the second radiation polarizer 129. .

The second radiation polarizer 129 may change the polarization direction of the interfering light L2I output from the Sanac interferometer 125.

The spectroscope 131 may selectively pass the interference light L2I parallel to its spectral axis (not shown).

The condensing lens 133 may provide the interference light L2I that has passed through the spectroscope 131 to the detection unit 140.

The detection unit 140 may receive the interference light L2I, generate a charge corresponding to the amount of light of the received interference light L2I, and generate measurement image data. The detection unit 140 of the present embodiment may include at least one of a two-dimensional image sensor including a plurality of pixels such as a charge coupled device (CCD) and a CMOS image sensor (CIS).

Again, referring to FIG. 1, the computing device 200 is electrically connected to the measurement device 100 to control and determine components of the measurement device 100.

The storage unit 220 of the computing device 200 stores various kinds of defect information according to measurement image data. For example, depending on the change in the rotation angle of the reflected light (L2_1, L2_2) and the intensity of the interference light (L2I) accordingly, whether it is an overlay defect, a tilt defect, a polygon defect, and furthermore, the overlay degree and tilt angle. You can save detailed information such as.

The processor 210 of the computing device 200 matches the measurement image data of the interference light L2I provided from the detection unit 140 with the defective parameters stored in the storage unit 220, so that the measurement object 20 It is possible to determine which defects have occurred in the deep part of the.

In this case, the computing device 200 may receive measurement image data provided from the detection unit 140 of the measurement device 100 through a transmission medium. The delivery medium may be used as a data link between the computing device 200 and the metrology device 100.

A general semiconductor device defect detection system requires information on a polarization phase change of reflected light and an asymmetric element of a Muller matrix in order to analyze a defect in a deep portion of a semiconductor device. In order to extract polarization phase information of reflected light, currently, a defect detection system of a semiconductor device has installed a plurality of expensive optical media for rotating the reflected light between a detection unit and a condensing lens (or analyzer).

In addition, in a computing device of a general semiconductor device failure detection system, a Muller matrix was generated through polarization phase information of reflected light, and through this, an analysis of the in-depth portion was determined. The Mueller matrix is a matrix expression describing a polarization state of coherent light, and may be expressed by the following equation.

<Equation 1>

That is, asymmetry defects in the deep part of the semiconductor device (measurement object) such as overlay defects, tilt defects, and polygon defects are difficult to detect with a simple image of light reflected from the surface of the measurement object 20, and asymmetric reflection characteristics and optical changes of the reflected light It was judged as a specific component of the Mueller matrix obtained through.

For example, specific components of the Muller matrix indicating a defect in the depth may be m13 and m31, m23 and m32, and m14 and m41, and conventional computing devices are m13+m31, m23+m32, and m14- The m41 value was calculated, and if the calculated value deviated from the reference value, it was determined as an asymmetry defect in the depth. Here, each of m13 and m31, m23 and m32, and m14 and m41 may have information on asymmetric reflection characteristics of light.

6 is a cross-sectional view illustrating an example of an overlay defect and a tilt defect of a semiconductor device. Referring to FIG. 6, the overlay defect is a defect when the upper contact hole H2 is shifted by a predetermined distance from the lower contact hole H1. The tilt failure is a failure when the upper contact hole H2 is formed to be inclined compared to the lower contact hole H1. Although not shown in the drawing, a polygon defect indicates a case in which the shape of the inside of the contact portion does not have a normal circular shape.

In order to detect asymmetric defects in a deep part of a semiconductor device, a conventional defect detection system must include a plurality of rotating optical members located in front of the detection unit and for rotating reflected light in various directions, and a calculation block for calculating and calculating the Muller matrix. It had to be accompanied.

However, the defect detection system of the present embodiment can determine the asymmetric defect of the deep part only with the Sanac interferometer 125 including the dove prism 127 without the provision of a plurality of expensive rotating optical members and calculation blocks as described above.

In detail, as described above, the dove prism 127 of the present embodiment is located on the optical path of the Sanak interferometer 125 composed of first and second reflected lights L2_1 and L2_2 traveling in opposite directions. . The first and second reflected lights L2_1 and L2_2 are incident on both ends 127a and 127b of the dove prism 127, respectively.

For example, when the dove prism 127 is rotated by 45°, the first reflected light L2_1 incident through one end 127a thereof is rotated by 90° in the first direction, and the other end 127b ) To print. Likewise, the second reflected light L2_2 incident through the other end 127b of the dove prism 127 may be rotated by -90° in the second direction and output through the one end 127a.

The first and second reflected lights L2_1 and L2_2 rotated 180° in opposite directions while proceeding in a direction facing each other in this way interfere in the Sanac interferometer 125. As described above, since the Sanac interferometer 125 measures interference of reflected lights traveling in a direction facing each other on the same optical path, the interference light can be more efficiently measured. The Sagnac interferometer 125 outputs the interference result of the first and second reflected lights L2_1 and L2_2 as interference light L2I.

For example, when there are no defects in the surface and the depth of the measurement object 20, the first and second reflected lights L2_1 and L2_2 that have the same directionality and are reflected from the measurement object 20 are the Sanac interferometer 125 ) And the dove prism 127 has a phase difference of 180°, so that destructive interference may occur.

On the other hand, when there is a defect in the surface and the depth of the measurement object 20, the first and second reflected light (L2_1, L2_2) interference occurs while passing through the Sanac interferometer 125 and the dove prism 127, Various types of interference light (L2I) can be output (please check this part).

In this embodiment, polarization information of the reflected lights L2_1 and L2_2 rotated by a predetermined angle through the dove prism 127 may be substantially the same as polarization information of the lights passing through a plurality of general rotating optical members. In other words, the polarization information of the reflected lights L2_1 and L2_2 rotated by a predetermined angle through the dove prism 127 may be substituted for a specific component of the Muller matrix in a general defect detection system.

In addition, the interference driving of the Sagnac interferometer 125 may serve as an operation block for calculating each component of the Mueller matrix in the general failure detection system.

Therefore, by passing through the Sanac interferometer 125 having the dove prism 127, it is possible to check whether the depth of the deep portion is defective without the provision of a plurality of rotating optical members and calculation blocks.

7 is a flowchart illustrating a method for determining a defect according to an embodiment of the present invention.

Referring to FIG. 7, the detection unit 140 extracts measurement image data of the interfering light L2I passing through the Sanac interferometer 125 (S1).

The processor 210 of the computing device 200 matches the defect parameters stored in the storage unit 220 with the defect information for the measurement image data (S2).

Next, the processor 210 determines the type and degree of the defect based on the defect parameter matched with the measurement image data (S3). The defect may include an overlay defect, a tilt defect, or a polygon defect of the depth portion. In terms of the degree of the defect, it may indicate an overlay degree, a tilt angle degree, and loss information of a contact cross section.

In the semiconductor device failure detection system according to the present embodiment, a Sanac interferometer having a dove prism is installed in its measuring device. Accordingly, various defects in the depth of the measurement object can be detected from the measurement image of the interference light obtained by rotation and interference of light reflected from the measurement object. Accordingly, since a plurality of rotating optical elements for rotating the reflected light at various angles and an operation block for extracting polarization phase information of the light are not required, manufacturing cost can be reduced.

Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the above embodiments, and various modifications are possible by those of ordinary skill in the art within the scope of the technical idea of the present invention. Do.

100: measuring device 125: sagnac interferometer
127: dove prism 140: detection unit
200: computer device 210: processor
220: storage unit

Claims (18)

A first optical unit for irradiating incident light onto the measurement object;
A second optical unit for condensing reflected light reflected from the measurement object; And
And a measurement device including a detection unit that outputs the light output from the second optical unit as measurement image data,
The second optical unit includes a Sanac interferometer for causing interference by advancing the reflected light in a direction facing each other on at least one optical path,
A semiconductor device failure detection system further comprising a dove prism for rotating the reflected light at a predetermined angle on the at least one optical path of the Sanac interferometer. The method of claim 1,
The first optical unit,
A light source that irradiates the incident light;
A polarizer polarizing the incident light;
A beam splitter for changing a path of light passing through the polarizer toward the surface of the measurement object; And
A failure detection system for a semiconductor device comprising an objective lens condensing the light passing through the beam splitter onto the surface of the measurement object. The method of claim 2,
A failure detection system for a semiconductor device, further comprising a first radiation polarizer between the polarizer and the beam splitter to change a polarization direction of light polarized by the polarizer. The method of claim 2,
The Sagnac interferometer,
It includes a plurality of mirrors and half mirrors sequentially arranged to form an optical path in the form of a closed curve,
The reflected light reflected from the measurement object is incident on the half mirror through the objective lens and the beam splitter,
The half mirror divides the reflected light into a first reflected light and a second reflected light, and the first reflected light is transmitted to a mirror located on one side of the half mirror, and the second reflected light is a mirror located on the other side of the half mirror. Defect detection system of semiconductor devices delivered to The method of claim 4,
The dove prism is
A failure detection system for a semiconductor device disposed in one selected from among the half mirrors and optical paths between the mirrors disposed adjacent to the half mirrors. The method of claim 5,
The dove prism is disposed so that its longitudinal direction and the optical path are parallel,
The dove prism rotates the first reflected light incident through one end thereof at a predetermined angle and outputs it to the other end,
A failure detection system for a semiconductor device, configured to rotate the second reflected light incident through the other end of the dove prism and output it to one end of the dove prism. The method of claim 6,
The Sagnac interferometer outputs an interference result of the rotated first reflected light and the rotated second reflected light output from the dove prism as interference light. The method of claim 4,
The half-mirror is configured to receive reflected light traveling in the same direction among the reflected light reflected from the measurement object. The method of claim 8,
The half mirror is a failure detection system of a semiconductor device including a beam splitter. The method of claim 7,
The second optical unit
A second radiation polarizer for changing a direction of polarization of the interfering light output from the Sanak interferometer;
A spectrometer for passing a component coincident with the spectral axis of the interfering light passing through the second radiation polarizer; And
A semiconductor device failure detection system comprising a condensing lens for condensing a component of the interference light passing through the spectroscope to the detection unit. The method of claim 1,
A storage unit for storing defect information according to various measurement images; And
A semiconductor device defect detection system further comprising a computing device including a processor configured to match the measurement image data provided from the detection unit and the defect information stored in the storage unit to determine a defect in a deep portion of the semiconductor device. A first optical unit including at least one optical medium for irradiating incident light onto an object to be measured;
An interferometer configured to receive reflected light having the same directionality reflected from the measurement object, divide, rotate, and interfere with the reflected light to output the interference light;
A detection unit that generates measurement image data of the interfering light; And
A semiconductor device failure detection system including a computer device that receives measurement image data of the interference light and determines a defect in the measurement object. The method of claim 12,
The interferometer,
First to third mirrors and half mirrors sequentially arranged to form an optical path in the form of a closed curve; And
A semiconductor device failure detection system including the half mirror and a dove prism disposed in one of an optical path between the first mirror and the third mirror disposed adjacent thereto. The method of claim 13,
The half mirror is configured to receive the reflected light and provide a first reflected light toward the first mirror and a second reflected light toward the third mirror. The method of claim 14,
The dove prism is disposed so that its longitudinal direction and the optical path are parallel,
The dove prism rotates the first reflected light incident through one end thereof at a predetermined angle and outputs it to the other end,
A defect detection system configured to rotate the second reflected light incident through the other end of the dove prism and output to one end of the dove prism. The method of claim 15,
The interferometer outputs an interference result of the rotated first reflected light and the rotated second reflected light output from the dove prism as the interference light. The method of claim 12,
Between the interferometer and the detection unit,
A radiation polarizer for adjusting or delaying the phase of the interfering light;
A spectrometer for passing a component coincident with the spectral axis of the interference light passing through the radiation polarizer; And
A failure detection system for a semiconductor device further comprising a condensing lens for condensing a component of the interference light passing through the spectrometer to the detection unit. The method of claim 12,
The computer device
A storage unit for storing defect information according to various measurement images; And
A semiconductor device defect detection system further comprising a computing device including a processor configured to match the measurement image data provided from the detection unit and the defect information stored in the storage unit to determine a defect in a deep portion of the semiconductor device.

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