Metrology apparatus for a semiconductor pattern, metrology system including the same and metrology method using the same

A metrology method includes obtaining a pattern reflection light reflected from an object by irradiating a first divided light, which is generated by reflecting a polarized light, to the object; obtaining a phase-controlled mirror reflection light reflected from a reflector by irradiating a second divided light, which is generated by transmitting the polarized light, to the reflector; and obtaining a pattern of the object based on an interference signal between the pattern reflection light and the mirror reflection light.

CROSS-REFERENCES TO RELATED APPLICATION

The present application claims priority under 35 U.S.C. §119(a) to Korean application number 10-2015-0111781, filed on Aug. 7, 2015, in the Korean Intellectual Property Office, which is incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

Various embodiments generally relate to a metrology apparatus for a semiconductor integrated circuit, more particularly, to a metrology apparatus for a semiconductor pattern, a metrology system including the same, and a metrology method using the same.

2. Related Art

As a semiconductor integrated circuit may have been highly integrated, a line width, a critical dimension, etc., of a semiconductor device may be continuously reduced.

Recently, a semiconductor device having a three-dimensional structure are being developed. Thus, the semiconductor integrated circuit may include a pattern having a high aspect ratio.

While fabricating the semiconductor integrated circuit an inspection may be made for detecting fabrication failure or pattern failure of the semiconductor integrated circuit by measuring the thickness and/or the width of each layer and/or the pattern formed by each stage of the fabrication.

The pattern failure may be determined based on whether the measured data falls within an allowable range. When the pattern is determined as abnormal, the pattern failure may be prevented by changing process parameters.

Apparatus for inspecting the pattern in the semiconductor integrated circuit are developed and studied. An optical measurement method may be a typical method for inspecting the pattern. In the optical measurement method, an optical signal may be irradiated to an object. An optical signal reflected from the object may be analyzed to determine the pattern failure.

However, as the semiconductor integrated circuit has a narrower pitch and a higher aspect ratio, it is required to develop a metrology method for measuring a pattern having a pitch less than a wavelength of a light source used for the optical measurement.

SUMMARY

According to an exemplary embodiment of the present disclosure, a metrology method may include: obtaining a pattern reflection light reflected from an object by irradiating a first divided light, which is generated by reflecting a polarized light, to the object; obtaining a phase-controlled mirror reflection light reflected from a reflector by irradiating a second divided light, which is generated by transmitting the polarized light, to the reflector; and obtaining a pattern of the object based on an interference signal between the pattern reflection light and the mirror reflection light.

According to an exemplary embodiment of the present disclosure, a metrology apparatus may include a light source suitable for emitting a light; a first polarizer suitable for generating a polarized light by polarizing the emitted light; a beam splitter suitable for dividing the polarized light into a first divided light and a second divided light; a second polarizer suitable for generating a pattern reflection light by polarizing the first divided light and irradiating the polarized first divided light to an object; a reflector suitable for generating a mirror reflection light by reflecting the second divided light; a wavelength plate suitable for controlling a phase of the mirror reflection light; a detector suitable for changing a polarization characteristic of an interference signal between the pattern reflection light and the mirror reflection light; and an image obtainer suitable for obtaining a pattern of the object based on the interference signal outputted from the detector.

According to an exemplary embodiment of the present disclosure, a metrology system may include a metrology apparatus suitable for: obtaining a pattern reflection light reflected from an object by irradiating a first divided light, which is generated by reflecting a polarized light, to the object; obtaining a phase-controlled mirror reflection light reflected from a reflector by irradiating a second divided light, which is generated by transmitting the polarized light, to the reflector; and obtaining a pattern of the object based on an interference signal between the pattern reflection light and the mirror reflection light; a stage suitable for moving the object; and a user device suitable for controlling the metrology apparatus and the stage to measure the pattern of the object based on operational parameters.

DETAILED DESCRIPTION

FIG. 1is a block diagram illustrating a metrology apparatus10for a semiconductor pattern in accordance with an exemplary embodiment of the present disclosure.

Referring toFIG. 1, the metrology apparatus10may include a light source101, a first polarizer103, a beam splitter105, a second polarizer107, a first objective lens109, a wavelength plate111, a second objective lens113, a reflector115, a detector117, a condenser119and an image obtainer121.

The light source101may irradiate a light to an object20. The light may include a coherent light. The coherent light may include two light waves having a same frequency and uniform phase difference to mutually interfere with each other. Alternatively, the light may include an incoherent light.

When a semiconductor pattern has a pitch less than a wavelength of the light, it is impossible to obtain information of the semiconductor pattern through direct imaging. Thus, the information of the semiconductor pattern may be obtained by an interferometer measuring the phase of the semiconductor pattern. In various embodiments. The interferometer may include the coherent light source or the incoherent light source. The metrology apparatus10may measure the semiconductor pattern having the pitch less than the wavelength of the light irradiated from the light source101.

The first polarizer103may form a polarized light by changing polarization characteristics of the light irradiated from the light source101. In various embodiments, the first polarizer103may include a variable polarizer for changing the polarization characteristics. The first polarizer103may transmit a secondary wave (S wave) or a primary wave (P wave) in accordance with analysis modes of the object20.

The beam splitter105may divide the polarized light into a first divided light and a second divided light. In various embodiments, the first divided light may include a reflection light reflected from the beam splitter105. The second divided light may include a transmission light transmitting through the beam splitter105.

The second polarizer107may irradiate the first divided light to the object20by changing polarization characteristics of the first divided light reflected from the beam splitter105. In various embodiments, the second polarizer107may include a radial polarizer. The radial polarizer may convert a linear polarization light into a radial polarization light or an azimuthal polarization light. The radial polarizer may provide the linear polarization light having a small spot size by concentrating the linear polarization light. Thus the second polarizer107may be effectively used for measuring the pattern of the object having the pitch less than the wavelength of the light.

In various embodiments, when the S wave is transmitted through the first polarizer103, the S wave may be converted into a transverse electronic wave (TE wave) by the second polarizer107. When the P wave is transmitted through the first polarizer103, the P wave may be converted into a transverse magnetic wave (TM wave) by the second polarizer107.

The first objective lens109may concentrate the light transmitting through the second polarizer107so that an image of the object20may be primarily formed on the image obtainer121.

After the light is irradiated to the object20through the first objective lens109, a pattern reflection light reflected from the object20may be incident to the first objective lens109. The pattern reflection light may be incident to the second polarizer107to be converted into a linear polarization light. The linearly polarized pattern reflection light may then be incident to the beam splitter105. In various embodiments, the pattern reflection light may be a measurement signal. The pattern reflection light or the measurement signal with or without polarization change by the object20may be incident to the beam splitter105through the second polarizer107.

The wavelength plate111may transmit the second divided light transmitting through the beam splitter105. The second divided light transmitting through the wavelength plate111may be incident to the reflector115through the second objective lens113. A mirror reflection light reflected from the reflector115may be again incident to the wavelength plate111. The mirror reflection light may be a reference signal.

In various embodiments, the wavelength plate111may include a quarter-wavelength plate. The wavelength plate111may have variable phase delay characteristics. Phase characteristics of the second divided light or the reference signal reflected from the reflector115may be controlled by the wavelength plate111. When the phase delay of the wavelength plate111is be about 0°, the reference signal may have polarization characteristics substantially the same as those of the light irradiated from the first polarizer103. When the wavelength plate111is rotated at an angle corresponding to a predetermined phase delay, the reference signal may have polarization characteristics different from those of the light irradiated from the first polarizer103. In various embodiments, the rotation angle of the wavelength plate111may be set as about 22.5°. However, the rotation angle of the wavelength plate111may not be restricted within a specific number.

The first divided light reflected from the beam splitter105may be incident to the object20. The pattern reflection light or the measurement signal reflected from the object20may be polarized or not polarized by the object20. Thus, when the first polarizer103transmits the S wave and the phase delay of the wavelength plate111is about 0°, interference between the S waves of the measurement signal and the reference signal may occur at the beam splitter105. In contrast, when the first polarizer103transmits the S wave, the pattern reflection light is reflected from the object20to the beam splitter105, and the wavelength plate111is rotated at an angle corresponding to the predetermined phase delay, interference between the P waves of the measurement signal and the reference signal may occur at the beam splitter105.

Similarly, when the first polarizer103transmits the P wave and the phase delay of the wavelength plate111is about 0°, interference between the P waves of the measurement signal and the reference signal may occur at the beam splitter105. In contrast, when the first polarizer103transmits the P wave, the pattern reflection light is reflected from the object20to the beam splitter105, and the wavelength plate111is rotated at an angle corresponding to the predetermined phase delay, such that interference between the S waves of the measurement signal and the reference signal may occur at the beam splitter105.

The pattern reflection light or the measurement signal incident to the beam splitter105from the object20and the mirror reflection light or the reference signal incident to the beam splitter105from the reflector115may be irradiated to the detector117.

The detector117may determine polarization characteristics in accordance with polarization modes to be analyzed. In various embodiments, the detector117may include a variable detector for changing the polarization characteristics.

When the polarization characteristics of the detector117is coincided with those of the first polarizer103and the wavelength plate111does not delay the phase of the mirror reflection light (e.g., the rotation angle of the wavelength plate111is about 0°), the image obtainer121may detect and photograph an image with respect to reflected components with the same polarization characteristics as those of the first polarizer103. This may be referred to as a first metrology mode.

In contrast, when the polarization characteristics of the detector117is vertical to those of the first polarizer103and the wavelength plate111is rotated at an angle corresponding to the predetermined phase delay, the image obtainer121may detect and photograph an image with respect to reflected components with the vertical polarization characteristics to those of the first polarizer103. This may be referred to as a second metrology mode.

According to an optical pattern measurement technology, when optical elements are complicatedly overlapped with each other, transitions of a light may be accurately represented by mathematically describing a polarized light. When an arrangement of the polarized light is represented as a matrix, polarization changes may be easily shown by simple matrix calculations. A typical example of the matrix may be the Jones Matrix.

In the Jones Matrix, diagonal components may indicate reflected components without polarization change and off-diagonal components may indicate reflected components with polarization change. Thus, the diagonal components may have the same polarization characteristics as those of the first polarizer103. In contrast, the off-diagonal components may have the vertical polarization characteristics to those of the first polarizer103.

In an exemplary embodiment of the present disclosure, the diagonal components without the changes of the polarization modes and the off-diagonal components with the changes of the polarization modes may be separately detected by controlling the first polarizer103, the second polarizer107, the wavelength plate111and the detector117.

When the pattern image is measured simultaneously in a TE mode and a TM mode, it may be difficult to accurately analyze the measured pattern due to interference between two phase information. However, according to an exemplary embodiment of the present disclosure, the polarization characteristics of the light may be controlled and the interference between the pattern reflection light (i.e., the measurement signal) and the mirror reflection light (i.e., the reference signal) may be analyzed according to the polarization modes. As a result, the metrology apparatus may obtain reliable pattern analysis.

Moreover, when adopting the radial polarizer as the second polarizer107, it is possible to measure an interference image to each of the TE mode and the TM mode. Therefore, information of the semiconductor pattern having a pitch less than a wavelength of the light irradiated from the light source101may be measured more precisely, and thus an ultra-fine pattern of the semiconductor integrated circuit may be easily measured.

FIG. 2is a block diagram illustrating a metrology system300for a semiconductor pattern in accordance with an exemplary embodiment of the present disclosure.FIG. 2shows the metrology system300including the metrology apparatus10described with reference toFIG. 1.

Referring toFIG. 2, a metrology system300for a semiconductor pattern may include a user device30, the metrology apparatus10and a stage40.

The user device30may control operations of the metrology apparatus10and the stage40based on operational parameters such as commands, control signals, data, etc.

As described with reference toFIG. 1, the metrology apparatus10may obtain the pattern image of the object20based on the interference signal between the pattern reflection light (i.e., the measurement signal), which may be obtained by irradiating the first divided light to the object20, and the mirror reflection light (i.e., the reference signal), which may be generated by reflecting the second divided light from the reflector115. In various embodiments, the metrology apparatus10may measure phases of the interference signal between the pattern reflection light (i.e., the measurement signal) and the mirror reflection light (i.e., the reference signal) in accordance with polarized directions of the light irradiated from the light source101and phase delay of the reference signal. That is, the metrology apparatus10may separately measure the TE mode and the TM mode in accordance with polarizations of the pattern reflection light.

The stage40may include a supporting unit410, a transferring unit420and a driving unit430. The object20may be placed on the supporting unit410.

The driving unit430may drive the transferring unit420under the control of the user device30. In various embodiments, the driving unit430may move the transferring unit420in horizontal directions (i.e., X-Y directions) and/or a vertical direction (i.e., Z direction). When the driving unit430moves the transferring unit420in the vertical direction, the pattern image of the object20may be more accurately measured.

FIG. 3is a block diagram illustrating the user device30ofFIG. 2.

The user interface320may include an input device and an output device. The user interface320may receive the operational parameters such as the commands, the data, etc., through the input device. The user interface320may output operation statuses, processing results, etc., of the metrology system300through the output device.

In various embodiments, the polarization characteristics of the first polarizer103, the second polarizer107and the detector117, the phase delay of the wavelength plate111and a driving power of the light source101according to metrology modes may be operational parameters to be inputted through the user interface320. The metrology modes may include the first metrology mode for measuring the interference between the pattern reflection light (i.e., the measurement signal) and the mirror reflection light (i.e., the reference signal) having the same polarization characteristic, and the second metrology mode for measuring the interference between the pattern reflection light and the mirror reflection light having vertical polarization characteristics.

The memory330may include a main memory and an auxiliary memory. Programs for driving the metrology system300, control data, application programs, the operational parameters, the processing results, etc., may be stored in the memory330.

The apparatus-controlling unit340may control the operations of the metrology apparatus10and the stage40. The apparatus-controlling unit340may control the polarization characteristics of the first polarizer103, the second polarizer107and the detector117according to the metrology modes in response to the operational parameters. The apparatus-controlling unit340may control the phase delay of the wavelength plate111also in response to the operational parameters. The apparatus-controlling unit340may provide the light source101with a predetermined power also in response to the operational parameters. The apparatus-controlling unit340may control the driving unit430in accordance with the operational parameters to provide the transferring unit420with desired directions and velocities.

The analyzing unit350may analyze the pattern of the object20based on the information of the image obtained by the metrology apparatus10.

In various embodiments, the analyzing unit350may analyze the pattern of the object20based on the image information of the first and second metrology modes separately obtained by the metrology apparatus10. As mentioned above, the first metrology mode may measure the interference between the pattern reflection light and the mirror reflection light having the same polarization characteristic. The second metrology mode may measure the interference between the pattern reflection light and the mirror reflection light having the vertical polarization characteristics.

Because the metrology apparatus10may separately perform the first metrology mode and the second metrology mode, the analyzing unit350may gather the image information in each of the first and second metrology modes to measure the pattern of the object20. In various embodiments, the analyzing unit350may use an analysis technique based on Jones Matrix. Alternatively, the analyzing unit350may use other analysis techniques.

FIG. 4is a flow chart illustrating a metrology method of the metrology system300in accordance with an exemplary embodiment of the present disclosure.

Referring toFIGS. 1 to 4, the object20may be placed on the supporting unit410of the stage40.

At step S101, the operational parameters such as the polarization characteristics of the first polarizer103, the second polarizer107and the detector117, the phase delay of the wavelength plate111, and the driving power of the light source101according to the metrology modes may be inputted through the user interface320. The metrology modes may include the first metrology mode for measuring the interference between the measurement signal and the reference signal (i.e., the pattern reflection light and the mirror reflection light) having the same polarization characteristics, and the second metrology mode for measuring the interference between the measurement signal and the reference signal having vertical polarization characteristics.

At step S103, the metrology apparatus10may be set for one of the first and second metrology modes based on the operational parameters. For example, the metrology apparatus10may be set for the first metrology mode.

At step S105, the metrology apparatus10may drive the light source105.

At step S107, the measurement signal, the reference signal and the interference signal may be generated based on the light emitted from the light source101as described with reference toFIG. 1. The image obtainer121may obtain the pattern of the object20based on the interference signal.

As described with reference toFIG. 1, the polarization characteristics of the light emitted from the light source101may be changed by the first polarizer103having the polarization characteristics in accordance with the operational parameters. For example, the first polarizer103may have the S wave polarization characteristic or the P wave polarization characteristic. The polarized light provided by the first polarizer103may be divided into the first divided light reflected from the beam splitter105and the second divided light transmitting through the beam splitter105.

The first divided light may be converted into the radial polarized light by the second polarizer107. When the S wave is transmitted through the first polarizer103, the S wave may be converted into the radial polarized light having the TE mode by the second polarizer107. The radial polarized light may be incident to the object20through the first objective lens109. The pattern reflection light reflected from the object20may be incident to the second polarizer107through the first objective lens109. The pattern reflection light may be converted into a linear polarized light by the second polarizer107. The pattern reflection light may be again incident to the beam splitter105.

The second divided light may be incident to the reflector115through the wavelength plate111and the second objective lens113. The second divided light may be reflected from the reflector115. The mirror reflection light may be incident to the beam splitter105through the wavelength plate111having the phase rotation angle (e.g., about 0°) in accordance with the operational parameters for the first metrology mode.

Thus, the interference signal between the pattern reflection light (i.e., the measurement signal) and the mirror reflection light (i.e., the reference signal) having the same polarization characteristic may be generated from the beam splitter105. The image of the interference signal may be provided to the condenser119through the detector117having the polarization characteristic substantially the same as that of the first polarizer103during the first metrology mode. The image obtainer121may obtain the image.

Therefore, the image information based on the interference signal between the pattern reflection light (measurement signal) and the mirror reflection light (reference signal) may be obtained.

During the first metrology mode, the first polarizer103may have the S wave polarization characteristic. The wavelength plate111may have the phase delay of about 0° to provide the reference signal having the same polarization as the measurement signal with. The detector117may have the S wave polarization characteristic. In contrast, during the first metrology mode when the first polarizer103has the P wave polarization characteristic, the wavelength plate111may have the phase delay of about 0° and the detector117may have the P wave polarization characteristic.

At step S109, the analyzing unit350may analyze the pattern image of the object20in the first metrology mode.

At step S111, the second metrology mode may then be performed.

Thus, at step S111, the operational parameter may be changed in accordance with the second metrology mode. Above-mentioned steps may then be performed sequentially.

During the second metrology mode, the interference signal between the pattern reflection light (i.e., the measurement signal) and the mirror reflection light (i.e., the reference signal) having the vertical polarization characteristic may be generated from the beam splitter105. When the operational parameters is set for the second metrology mode, the wavelength plate111may be provided with a rotation angle (e.g., about 22.5°) corresponding to the predetermined phase delay. The detector117may have the polarization characteristic substantially vertical to that of the first polarizer103.

For example, when the first polarizer103has the S wave polarization characteristic during the second metrology mode, the wavelength plate111may be provided with the rotation angle of about 22.5°. The detector117may have the P wave polarization characteristic. In contrast, when the first polarizer103has the P wave polarization characteristic during the second metrology mode, the wavelength plate111may be provided with the rotation angle of about 22.5°. The detector117may have the S wave polarization characteristic.

At step S109, the analyzing unit350may analyze the pattern image of the object20during the second metrology mode. The analyzing unit350may gather and analyze the images of the first metrology mode and the second metrology mode to obtain a final pattern of the object20.

In various embodiments, the pattern of the object20may be detected by vertically moving the transferring unit420using the driving unit430. When the pattern of the object20is detected with position changes of the object20in the vertical direction, the pattern image may be more accurately measured.

Although the semiconductor integrated circuit may have the high aspect ratio and the patterns having the pitch less than the wavelength of the light, the pattern image of the object may be reliably obtained using the metrology apparatus. As a result, generations of pattern failures may be prevented so that yields of semiconductor devices may be improved.

The above embodiment of the invention is illustrative and not limitative. Various alternatives and equivalents are possible. The invention is not limited by the embodiment described herein. Nor is the invention limited to any specific type of semiconductor device. Other additions, subtractions, or modifications are obvious in view of the invention and are intended to fall within the scope of the appended claims.