CN115373229A - Device for realizing holographic photoetching by using semiconductor laser - Google Patents
Device for realizing holographic photoetching by using semiconductor laser Download PDFInfo
- Publication number
- CN115373229A CN115373229A CN202211042313.4A CN202211042313A CN115373229A CN 115373229 A CN115373229 A CN 115373229A CN 202211042313 A CN202211042313 A CN 202211042313A CN 115373229 A CN115373229 A CN 115373229A
- Authority
- CN
- China
- Prior art keywords
- laser
- blue laser
- grating
- mode
- longitudinal mode
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70008—Production of exposure light, i.e. light sources
- G03F7/70025—Production of exposure light, i.e. light sources by lasers
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70408—Interferometric lithography; Holographic lithography; Self-imaging lithography, e.g. utilizing the Talbot effect
Abstract
The invention discloses a device for realizing holographic lithography by using a semiconductor laser, which can be applied to the technical field of semiconductor photoelectric devices. The device comprises: the device comprises a laser emitting assembly, a detection assembly and an interference device. The laser emitting assembly includes: the laser comprises a blue laser diode, a collimating lens, a driving/temperature control module and a grating, wherein the grating forms a grating external cavity structure and is used for generating and outputting single longitudinal mode blue laser; the detection assembly is used for monitoring the spectrum and the light intensity of the single longitudinal mode blue laser in real time; and the interference device is used for executing the holographic photoetching process on the experimental sample by using the single longitudinal mode blue laser. The invention generates and outputs single longitudinal mode blue laser through the grating external cavity structure, realizes the application of the single longitudinal mode blue laser to the holographic lithography technology, has simple and convenient device, can prepare small-area Bragg grating, is suitable for the development of distributed feedback lasers, promotes the industrial application of the distributed feedback lasers, and simultaneously promotes the research, development and application of blue-violet light to ultraviolet light semiconductor laser diodes.
Description
Technical Field
The invention relates to the technical field of semiconductor photoelectric devices, in particular to a device for realizing holographic lithography by using a semiconductor laser.
Background
The traditional ridge waveguide edge-emitting semiconductor laser can integrate a distributed feedback Bragg grating structure (DFB) to realize single longitudinal mode laser, has narrow line width, is tunable and easy to carry, and is an important device in the field of photoelectric information.
The Bragg grating period is usually 200-300 nm, the conventional photoetching is difficult to realize, and in order to design the grating period in the range, the Bragg grating period is usually prepared by scanning point by using electron beam lithography, so that the problems of slow processing, high cost and writing field splicing are introduced. The laser holographic lithography technology can realize simple and convenient preparation of the Bragg grating, but a 325nm HeCr laser with high power and good coherence is required; in order to maintain high spatial coherence, the laser also needs to use a pinhole for spatial filtering, and the pinhole is far away from the sample wafer, so that the laser power utilization rate is low. In semiconductor lasers, in recent years, a single-frequency laser for mode selection and frequency stabilization by an integrated Bragg grating appears, the coherence length reaches 1 meter, but the whole structure is complex and the cost is high.
Disclosure of Invention
In view of the above problems, the present invention provides an apparatus for implementing holographic lithography using a semiconductor laser, which uses a grating to construct an external cavity structure to generate single longitudinal mode laser, reduces coherence caused by fiber mode dispersion, and implements small-area laser holographic lithography using an interference device.
According to an embodiment of the present invention, there is provided an apparatus for implementing holographic lithography using a semiconductor laser, including:
a laser emitting assembly comprising:
a blue laser diode adapted to generate a laser beam;
the collimating lens is suitable for converting the laser beam into a first quasi-parallel beam and converting the external cavity laser beam into a second quasi-parallel beam;
the driving/temperature control module is suitable for generating driving current with adjustable magnitude for the blue laser diode, and controlling the temperature through a semiconductor thermoelectric refrigeration component and a fan/radiating fin radiating component so as to ensure that the blue laser diode stably works; providing the coaxial mounting base of the blue laser diode and the collimating lens;
a grating configured as a reflective periodic reticle grating adapted to produce multiple orders of diffraction, including negative first order diffraction, zero order diffraction, and positive first order diffraction, on said first quasi-parallel beam; the negative first-order diffraction is incident into the blue laser diode again to provide optical feedback to the blue laser diode to form a grating external cavity structure and generate the external cavity laser beam; the negative first-order diffraction is also suitable for mode selection in the grating external cavity structure by using a mode competition mechanism, so that the second quasi-parallel light beam is separated into single longitudinal mode blue laser, and the zero-order diffraction is suitable for outputting the single longitudinal mode blue laser;
the imaging spectrometer is suitable for monitoring the spectrum and the light intensity of the single longitudinal mode blue laser in real time based on the positive first-order diffraction; and
and the interference device is suitable for executing the holographic photoetching process on the experimental sample by using the single longitudinal mode blue laser from the laser emission assembly.
According to the embodiment of the invention, the grating is formed by preparing a single-layer metal aluminum layer on the plane mirror and scribing lines by utilizing the mechanical processing period of a grating master mask; the first quasi-parallel light beam is incident on the grating period reticle to generate reflection type light diffraction; the light diffraction interference generated in the direction of the optical path difference being integral multiple of the wavelength of the incident light is enhanced, so that the first quasi-parallel light beam generates multi-order diffraction.
According to an embodiment of the present invention, the above-mentioned negative first-order diffraction is further adapted to use a mode competition mechanism to perform mode selection in the above-mentioned grating external cavity structure, so that the above-mentioned second quasi-parallel light beam is separated into single longitudinal mode blue laser, including:
the threshold current of the blue laser diode is 130mA, and the second quasi-parallel light beam is separated into multi-longitudinal-mode blue laser under the condition that the difference between the threshold current and the driving current is 50 mA; and under the condition that the difference between the threshold current and the driving current is 10-30 mA, the second quasi-parallel light beam is separated into few longitudinal mode blue light laser or single longitudinal mode blue light laser, and the mode selection is carried out by utilizing the mode competition mechanism to generate the single longitudinal mode blue light laser.
According to the embodiment of the invention, the distance between the grating and the blue laser diode is set, so that the interval between adjacent longitudinal modes of the single longitudinal mode blue laser is more than or equal to 0.008nm.
According to an embodiment of the present invention, the apparatus for implementing holographic lithography by using a semiconductor laser described above may further include:
the transmission assembly is suitable for maintaining the spatial coherence of the single longitudinal mode blue laser and performing spot conversion, and comprises:
the first optical fiber collimating lens is arranged adjacent to the grating and is suitable for focusing the single longitudinal mode blue laser generated by the grating external cavity structure;
the inlet of the first single-mode fiber is positioned at the focus of the first fiber collimating lens and is suitable for converting the focused single-longitudinal-mode blue laser into a first circular Gaussian beam; the core diameter of the first single-mode fiber is used for carrying out spatial filtering on the single longitudinal mode blue laser, keeping the spatial coherence of the single longitudinal mode blue laser and adjusting the polarization direction of the output first circular Gaussian beam; and
and the convex surface of the first plano-convex lens faces the interference device, and the plane faces the optical fiber socket connected to the outlet of the first single-mode optical fiber, so that the first circular Gaussian beam is focused into a first parallel beam suitable for executing a holographic photoetching process on an experimental sample.
According to an embodiment of the present invention, the apparatus for implementing holographic lithography by using a semiconductor laser device may further include a detection module, including:
the second optical fiber collimating lens is arranged close to the grating and is suitable for focusing the single longitudinal mode blue laser generated by the grating external cavity structure;
the inlet of the second single-mode fiber is positioned at the focus of the second fiber collimating lens and is suitable for converting the focused single longitudinal mode blue laser into a second circular Gaussian beam; and
and a lens assembly adapted to convert the second circular Gaussian beam from the second single mode fiber into a second parallel beam and deliver the second parallel beam to the imaging spectrometer.
According to an embodiment of the present invention, the above-mentioned interference device includes: the included angle between the plane mirror and the sample rack is 90 degrees;
the sample rack is adhered with an experimental sample;
and simultaneously irradiating the plane mirror and the sample holder by using the first parallel light beam, wherein the reflected light of the plane mirror and the light directly irradiating the experimental sample wafer generate interference on the experimental sample wafer, and the holographic photoetching process of one period is completed.
According to an embodiment of the present invention, the interference device is disposed on a compound rotary stage, and is configured to adjust an incident tilt angle and a spot position of the first parallel beam to perform the holographic lithography process with different periods.
According to an embodiment of the present invention, the first single mode fiber and the second single mode fiber are made of fused silica material, and are adapted to transmit the single longitudinal mode blue laser with a wavelength of 405 nm.
According to the embodiment of the invention, the collimating lens is a non-spherical biconvex lens with the focal length of 3mm and is made of optical glass, and the surface of the collimating lens is plated with an antireflection film;
the first optical fiber collimating lens and the second optical fiber collimating lens are aspheric biconvex lenses and are made of quartz materials;
the first plano-convex lens is made of optical glass;
the lens group consists of a third fiber collimating lens and a second plano-convex lens, wherein the third fiber collimating lens is close to the second single-mode fiber, and the convex surface of the second plano-convex lens faces the imaging spectrometer.
According to the device for realizing holographic lithography by using the semiconductor laser, the blue-ray semiconductor laser diode is used for generating single longitudinal mode blue-ray laser by constructing the external cavity structure through the grating, the single-mode optical fiber is used for outputting the circular Gaussian spot, the mode dispersion of the optical fiber is reduced, and the interference device is used for realizing small-area laser holographic lithography. In addition, the third-order diffraction generated by the grating can realize better wavelength selectivity.
Drawings
FIG. 1 is a simplified schematic diagram of a single longitudinal mode blue laser generation and apparatus for holographic lithography according to an embodiment of the present invention;
FIGS. 2 (a), (b) and (c) are atomic force micrographs of a photoresist grating structure according to an embodiment of the invention, wherein (a), (b) and (c) correspond to grating periods of 310nm, 250nm and 210nm, respectively;
FIG. 3 is a scanning electron microscope image of a photoresist grating structure according to an embodiment of the invention;
FIG. 4 is an optical micrograph of the isocline interference fringes produced on the surface of the photoresist by a single longitudinal mode blue laser under the condition of fiber mode dispersion, with a scale bar of 200 μm.
Description of the reference numerals:
1: a blue laser diode;
2: a drive/temperature control module;
3: a collimating lens;
4: a grating;
5: a first fiber collimating lens;
6: a second fiber collimating lens;
7: a first single mode optical fiber;
8: a second single mode optical fiber;
9: a lens group;
10: an optical fiber socket;
11: a first plano-convex lens;
12: an interference device;
13: an imaging spectrometer;
14: a zero order diffracted beam;
15: a positive first order diffracted beam;
16: a first parallel beam;
17: a plane mirror;
18: a sample holder;
19: a composite rotary stage;
20: and (4) testing sample pieces.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the accompanying drawings in combination with the embodiments.
It is to be understood that such description is merely illustrative and not intended to limit the scope of the present invention. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention. It may be evident, however, that one or more embodiments may be practiced without these specific details. Furthermore, in the following description, descriptions of well-known technologies are omitted so as to avoid unnecessarily obscuring the concepts of the present invention.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "comprising" as used herein indicates the presence of the features, steps, operations but does not preclude the presence or addition of one or more other features.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It is noted that the terms used herein should be interpreted as having a meaning that is consistent with the context of this specification and should not be interpreted in an idealized or overly formal sense.
FIG. 1 is a simplified schematic diagram of a single longitudinal mode blue laser generation and apparatus for holographic lithography according to an embodiment of the present invention.
An apparatus for implementing holographic lithography using a semiconductor laser according to an exemplary embodiment of the present invention, as shown in fig. 1, includes: a laser emitting assembly, an imaging spectrometer 13 and an interference device 13. A laser emitting assembly comprising: a blue laser diode 1, a collimating lens 3, a driving/temperature control module 2 and a grating 4. The blue laser diode 1 is adapted to generate a laser beam; the collimating lens 3 has a small focal length, is suitable for converting the laser beam into a first quasi-parallel beam and is also suitable for converting the external cavity laser beam into a second quasi-parallel beam; the driving/temperature control module 2 is suitable for generating driving current with adjustable size for the blue laser diode, and controls the temperature through the semiconductor thermoelectric refrigeration part and the fan/radiating fin radiating part to ensure that the blue laser diode works stably; simultaneously providing a coaxial mounting base for the blue laser diode and the collimating lens 3; the grating 4 is constructed as a reflective periodic reticle grating, is used as an optical output coupler and is suitable for generating multi-order diffraction including negative first-order diffraction, zero-order diffraction and positive first-order diffraction on the first quasi-parallel light beam; the negative first-order diffraction is incident into the blue laser diode again to provide optical feedback for the blue laser diode to form a grating external cavity structure and generate an external cavity laser beam; the negative first-order diffraction is also suitable for mode selection in the grating external cavity structure by using a mode competition mechanism, so that the second quasi-parallel light beam is separated into single longitudinal mode blue laser, and the zero-order diffraction is suitable for outputting the single longitudinal mode blue laser; the imaging spectrometer 13 is suitable for monitoring the spectrum and the light intensity of the single longitudinal mode blue laser in real time based on the positive first-order diffraction; and an interference device 12 adapted to perform a holographic lithography process on the test specimen 20 using a single longitudinal mode blue laser from the laser emitting assembly.
According to the embodiment of the invention, the grating is formed by preparing a single-layer metal aluminum layer on a plane mirror and carrying out periodic line scribing by utilizing a grating master mask machining; the first quasi-parallel light beam is incident on the grating period reticle to generate reflection type light diffraction; the light diffraction interference generated in the direction of the optical path difference being integral multiple of the wavelength of the incident light is enhanced, so that the first quasi-parallel light beam generates multi-order diffraction.
According to the embodiment of the invention, single longitudinal mode blue laser can be generated more easily around the threshold current of the blue laser diode 1.
According to an embodiment of the present invention, the negative first order diffraction is further adapted to use a mode competition mechanism to perform mode selection within the grating external cavity structure, such that the second quasi-parallel beam is separated into single longitudinal mode blue lasers. Under the condition that the difference between the threshold current and the driving current is 50mA, the second quasi-parallel light beam is separated into multi-longitudinal-mode blue laser; under the condition that the difference between the threshold current and the driving current is 10-30 mA, the second quasi-parallel light beam is separated into few longitudinal mode blue light lasers or single longitudinal mode blue light lasers, and mode selection is carried out by utilizing a mode competition mechanism to generate single longitudinal mode blue light lasers.
According to the embodiment of the invention, under the condition that the difference between the threshold current and the driving current is 10-30 mA, the second quasi-parallel light beam is separated into few longitudinal modes or single longitudinal mode blue laser, and the mode selection is carried out by utilizing a mode competition mechanism to generate the single longitudinal mode blue laser. Specifically, under the condition that a plurality of different longitudinal modes of a second quasi-parallel light beam in the grating external cavity structure are simultaneously excited, by utilizing the gain difference between the different longitudinal modes and regulating and controlling the angle of the grating or the driving current of the blue laser diode, the excitation of one longitudinal mode of the grating external cavity structure occupies most current carriers, the excitation is relatively favorable, the excitation of other adjacent longitudinal modes occupies fewer current carriers, the excitation is relatively weaker, the output of few longitudinal mode blue laser is inhibited, and the single longitudinal mode blue laser is output.
According to the embodiment of the invention, the distance between the grating and the blue laser diode is set to be less than 10mm, so that the interval between adjacent longitudinal modes of the single longitudinal mode blue laser is more than or equal to 0.008nm, the larger the longitudinal mode interval is, the higher the grating dispersion is, and the better the mode selection effect is.
According to the embodiment of the invention, the laser beam generated by the blue laser diode 1 is in an elliptical line-like shape and is focused into a parallel beam after passing through the collimating lens 3.
According to the embodiment of the invention, the driving current of the blue laser diode 1 and the angle of the grating are finely adjusted based on the spectrum and the light intensity of the single longitudinal mode blue laser monitored by the imaging spectrometer 13, so that the single longitudinal mode blue laser is ensured to be stably output.
According to an embodiment of the present invention, the apparatus for implementing holographic lithography by using a semiconductor laser further includes: a transmission assembly adapted to maintain spatial coherence of single longitudinal mode blue laser and to perform spot conversion, the transmission assembly comprising: a first fiber collimating lens 5, a first single mode fiber 7, and a first plano-convex lens 11. The first optical fiber collimating lens 5 is arranged adjacent to the grating and is suitable for focusing the single longitudinal mode blue laser generated by the grating external cavity structure; the inlet of the first single-mode fiber 7 is positioned at the focus of the first fiber collimating lens 5 and is suitable for converting the focused single-longitudinal-mode blue laser into a first circular Gaussian beam; the core diameter of the first single-mode fiber 7 performs spatial filtering on the single longitudinal mode blue laser, and the spatial coherence of the single longitudinal mode blue laser is kept; the first plano-convex lens 11 has a focal length of 20mm, its convex surface facing the interference device and its flat surface facing the optical fiber socket 10 connected at the exit of the first single-mode optical fiber, to focus the first circular gaussian beam into a first parallel beam suitable for performing a holographic lithography process on the test specimen 20.
According to an embodiment of the present invention, the apparatus for implementing holographic lithography by using a semiconductor laser further includes a detection module, where the detection module includes: a second fiber collimating lens 6, a second single mode fiber 8 and a lens group 9. The second optical fiber collimating lens 6 is arranged close to the grating and is suitable for focusing the single longitudinal mode blue laser generated by the grating external cavity structure; the inlet of the second single-mode fiber 8 is positioned at the focus of the second fiber collimating lens 6 and is suitable for converting the focused single-longitudinal-mode blue laser into a second circular Gaussian beam; the lens assembly 9 is adapted to convert the second circular gaussian beam from the second single mode fiber 8 into a second parallel beam and deliver the second parallel beam to the imaging spectrometer 13.
According to the embodiment of the invention, the first single-mode fiber and the second single-mode fiber are made of fused silica materials and are suitable for transmitting single longitudinal mode blue laser with the wavelength of 405 nm.
According to the embodiment of the invention, the single longitudinal mode blue laser has a real spectral line width of < 1MHz, so that the single longitudinal mode blue laser has a large coherence length.
According to the embodiment of the invention, the optical fiber socket 10 is pluggable and used for fixing a single-mode optical fiber, and once the imaging spectrometer 13 detects single longitudinal mode blue light, the beam direction and the polarization direction of the optical fiber mode are adjusted in advance to realize holographic lithography.
According to an embodiment of the invention, an interference device comprises: a plane mirror 17 and a sample rack 18 which are vertically arranged, and the included angle is 90 degrees; the sample rack 18 is stuck with an experimental sample 20; the plane mirror 17 and the sample holder 18 are simultaneously irradiated by the first parallel beam, and the reflected light of the plane mirror 17 and the light directly irradiating the experimental sample 20 generate interference on the experimental sample 20, thereby completing the holographic lithography process of one period.
According to an embodiment of the present invention, an interference device is placed on the compound rotary stage 19 for adjusting the incidence inclination angle and spot position of the first parallel beam to perform a different cycle of the holographic lithography process.
According to embodiments of the present invention, the illumination parameters (intensity, time) may be determined from the light intensity monitored by the imaging spectrometer in real time.
According to the embodiment of the invention, at the intersection line of the plane mirror and the experimental sample wafer, the optical path difference of incident light and reflected light is equal to the integral multiple of the wavelength of the incident light, the light interference generated in the direction is enhanced, the exposed photoresist dose is large, and the loss of the photoresist after development is maximum, so that the holographic lithography effect is optimal.
According to the embodiment of the invention, the larger the incidence inclination angle of the first parallel light beam is, the more divergent the light spots irradiated on the experimental sample wafer are, the lower the illumination intensity is, and the longer the illumination time is required for completing the holographic lithography.
According to the embodiment of the invention, the experimental sample wafer is a semiconductor substrate wafer, the surface of the experimental sample wafer is coated with PGMEA diluted positive photoresist in advance, and the thickness of the photoresist is 150nm after the photoresist is dried by a hot plate.
According to the embodiment of the invention, the Bragg grating structure is prepared on an experimental sample wafer through a holographic photoetching process and a developing process, the geometrical size of the photoresist holographic stripe on the surface of the Bragg grating structure is represented by an atomic force microscope or a scanning electron microscope, and the Bragg grating structure is further transferred into a semiconductor layer or a dielectric layer through an etching process.
According to the embodiment of the invention, the polarization direction of the HE11 mode output by the first single-mode fiber 7 can be adjusted by rotating the angle of the fiber socket 10 or adding a polarizing plate, so that a small period grating is prepared to improve the interference contrast at a large incidence inclination angle.
According to an embodiment of the present invention, the incidence inclination of the first parallel beam can be adjusted by rotating the composite rotary stage 19 and the interference device, respectively.
According to the embodiment of the invention, the collimating lens 3 is a non-spherical biconvex lens with a focal length of 3mm and is made of optical glass, and the surface of the collimating lens is plated with an antireflection film; the first optical fiber collimating lens 5 and the second optical fiber collimating lens 6 are aspheric biconvex lenses and are made of quartz materials; a first plano-convex lens 11 made of optical glass; and the lens group 9 consists of a third fiber collimating lens and a second plano-convex lens, wherein the third fiber collimating lens is close to the second single-mode fiber 8, and the convex surface of the second plano-convex lens faces the imaging spectrometer 13.
According to an embodiment of the present invention, the apparatus for implementing holographic lithography using a semiconductor laser further includes a yellow region for photoresist spin coating and developing. The device for realizing holographic lithography by using the semiconductor laser needs to be placed in a strictly lightproof experimental environment.
According to an exemplary embodiment of the present invention, there is provided a method of implementing holographic lithography using a semiconductor laser, including:
s1: the method comprises the steps that a grating external cavity structure is used for generating single longitudinal mode blue laser in a semiconductor laser diode by utilizing a mode competition mechanism, the generation of multiple longitudinal mode blue laser or few longitudinal mode blue laser caused by temperature drift of a semiconductor device is avoided by fine adjustment of driving current and the angle of a grating, and the spectrum and the light intensity of the single longitudinal mode blue laser are monitored in real time by an imaging spectrometer;
s2: collecting a second quasi-parallel light beam into the single-mode fiber through the fiber collimating lens and the single-mode fiber to output a circular Gaussian beam, adjusting the position of the first plano-convex lens to enable the second quasi-parallel light beam to be focused and be incident on a plane mirror and a sample frame of the interference device, and adjusting the superposition of an incident light spot and a reflected light spot through the composite rotary objective table;
s3: the method comprises the following steps of spin-coating a positive photoresist diluted by PGMEA (propylene glycol methyl ether acetate) on the surface of an experimental sample wafer in advance, drying the positive photoresist by a hot plate to form a photoresist with the thickness of 150nm, attaching the experimental sample wafer on a sample frame of an interference device for executing a holographic photoetching process, wherein the illumination time is determined by the light intensity monitored by an imaging spectrometer in real time;
s4: generating a photoresist grating pattern on the experimental sample after holographic lithography through a developing process;
s5: and characterizing the geometric dimension of the photoresist grating pattern by using an atomic force microscope and a scanning electron microscope, and adjusting and optimizing holographic lithography parameters.
Fig. 2 (a), fig. (b) and fig. (c) are atomic force micrographs of a photoresist grating structure according to an embodiment of the present invention, wherein fig. (a), fig. (b) and fig. (c) correspond to grating periods of 310nm, 250nm and 210nm, respectively.
As shown in FIG. 2, the holographic lithography process can generate holographic fringes (200-300 nm) with different periods under the condition of different incidence inclination angles, and the holographic fringes can be used for Bragg grating preparation and laser development. For the case of large incidence tilt angles, the contrast of the holographic fringes thereof decreases. In order to improve the interference contrast at a large incidence angle so as to prepare a small period grating, the polarization direction of the HE11 mode output by the first single-mode fiber 7 can be adjusted, i.e., the angle of the fiber socket 10 is rotated or a polarizing plate is added.
FIG. 3 is a scanning electron microscope image of a photoresist grating structure according to an embodiment of the invention.
As shown in fig. 3, the holographic fringes generated by the above-mentioned holographic lithography process are uniformly distributed, but the contrast ratio needs to be further improved.
FIG. 4 is an optical micrograph of the isocline interference fringes produced on the surface of the photoresist by the single longitudinal mode blue laser under the condition of fiber mode dispersion, with a scale bar of 200 μm.
As shown in fig. 4, the spatial coherence of the single longitudinal mode blue laser is easily affected by the mode dispersion of the first single mode fiber 7, which causes the spatial coherence to be poor and weak divergence exists, that is, the single longitudinal mode blue laser with the same frequency and phase has a certain spot size and generates phase mixing in the first single mode fiber 7, so as to reduce the coherence length, and generate equal-inclination interference lithography fringes on the experimental sample 20 of the interference device 12, with a period of about 50um, which is far beyond the period of the hologram lithography. Therefore, the phase and the large coherence length of the single longitudinal mode blue laser can be kept by adopting a proper geometric optical design, and the high-contrast holographic photoetching stripes are realized.
According to the device for realizing holographic lithography by using the semiconductor laser, disclosed by the embodiment of the invention, the blue light semiconductor laser diode is used for generating single longitudinal mode blue light laser through the grating structure external cavity structure, the coherence caused by optical fiber mode dispersion is reduced, the interference device is adopted for realizing 5mm multiplied by 5mm small-area laser holographic lithography, the device is simple, convenient, economic and practical, the preparation of the Bragg grating of the small area can be carried out, the period of the obtained Bragg grating is 200-300 nm, and the device is suitable for developing DFB lasers and promoting the industrial application of the DFB lasers; meanwhile, the research and development and application of blue-violet to ultraviolet semiconductor laser diodes are promoted.
The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only examples of the present invention, and should not be construed as limiting the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. An apparatus for performing holographic lithography using a semiconductor laser, comprising:
a laser emitting assembly comprising:
a blue laser diode adapted to generate a laser beam;
the collimating lens is suitable for converting the laser beam into a first quasi-parallel beam and converting the external cavity laser beam into a second quasi-parallel beam;
the driving/temperature control module is suitable for generating driving current with adjustable magnitude for the blue-ray laser diode and controlling the temperature through a semiconductor thermoelectric refrigeration component and a fan/radiating fin radiating component so as to ensure that the blue-ray laser diode stably works; providing a coaxial mounting base for the blue laser diode and the collimating lens simultaneously; and
a grating configured as a reflective periodic reticle grating adapted to produce multiple orders of diffraction, including negative first order diffraction, zero order diffraction, and positive first order diffraction, of the first quasi-parallel beam; the negative first-order diffraction is incident into the blue laser diode again so as to provide optical feedback for the blue laser diode to form a grating external cavity structure and generate the external cavity laser beam; the negative first order diffraction is further adapted to utilize a mode competition mechanism to perform mode selection within the grating external cavity structure such that the second quasi-parallel beam is split into single longitudinal mode blue lasers, and the zero order diffraction is adapted to output the single longitudinal mode blue lasers;
the imaging spectrometer is suitable for monitoring the spectrum and the light intensity of the single longitudinal mode blue laser in real time based on the positive first-order diffraction; and
and the interference device is suitable for executing the holographic photoetching process on the experimental sample by using the single longitudinal mode blue laser from the laser emission assembly.
2. The apparatus of claim 1, wherein,
the grating is formed by preparing a single-layer metal aluminum layer on the plane mirror and scribing lines by utilizing a mechanical processing period of a grating master plate; the first quasi-parallel light beam is incident on the grating period reticle to generate reflection type light diffraction; and the light diffraction interference generated in the direction of which the optical path difference is integral multiple of the wavelength of the incident light is enhanced, so that the first quasi-parallel light beam generates multi-order diffraction.
3. The apparatus of claim 1, wherein the negative first order diffraction is further adapted to use a mode competition mechanism to select a mode within the grating external cavity structure such that the second quasi-parallel beam is separated into a single longitudinal mode blue laser, comprising:
the threshold current of the blue laser diode is 130mA, and under the condition that the difference between the threshold current and the driving current is 50mA, the second quasi-parallel light beam is separated into multi-longitudinal-mode blue laser; under the condition that the difference between the threshold current and the driving current is 10-30 mA, the second quasi-parallel light beam is separated into few longitudinal mode blue light laser or single longitudinal mode blue light laser, and the mode selection is carried out by utilizing the mode competition mechanism to generate the single longitudinal mode blue light laser.
4. The device of claim 1, wherein a spacing between the grating and the blue laser diode is set to be <10mm such that adjacent longitudinal mode spacing of the single longitudinal mode blue laser is ≥ 0.008nm.
5. The apparatus of claim 1, further comprising:
a transmission assembly adapted to maintain spatial coherence of the single longitudinal mode blue laser and perform spot conversion, comprising:
the first optical fiber collimating lens is arranged close to the grating and is suitable for focusing the single longitudinal mode blue laser generated by the grating external cavity structure;
the inlet of the first single-mode fiber is positioned at the focus of the first fiber collimating lens and is suitable for converting the focused single-longitudinal-mode blue laser into a first circular Gaussian beam; the core diameter of the first single-mode fiber is used for carrying out spatial filtering on the single longitudinal mode blue laser, keeping the spatial coherence of the single longitudinal mode blue laser and adjusting the polarization direction of the output first circular Gaussian beam; and
the convex surface of the first plano-convex lens is right opposite to the interference device, and the plane orientation is connected with the optical fiber socket at the outlet of the first single-mode optical fiber, so that the first circular Gaussian beam is focused into a first parallel beam suitable for executing a holographic photoetching process on an experimental sample.
6. The apparatus of claim 5, further comprising a detection component comprising:
the second optical fiber collimating lens is arranged close to the grating and is suitable for focusing the single longitudinal mode blue laser generated by the grating external cavity structure;
the inlet of the second single-mode fiber is positioned at the focus of the second fiber collimating lens and is suitable for converting the focused single longitudinal mode blue laser into a second circular Gaussian beam; and
and the lens group is suitable for converting the second circular Gaussian beam from the second single-mode optical fiber into a second parallel beam and transmitting the second parallel beam to the imaging spectrometer.
7. The apparatus of claim 5, wherein the interference device comprises: the included angle between the plane mirror and the sample rack which are vertically arranged is 90 degrees;
an experimental sample is stuck on the sample rack;
and simultaneously irradiating the plane mirror and the sample holder by using the first parallel light beam, wherein the reflected light of the plane mirror and the light directly irradiating the experimental sample wafer generate interference on the experimental sample wafer, and the holographic photoetching process of one period is completed.
8. The apparatus of claim 7, wherein the interference device is placed on a compound rotary stage for adjusting the incidence tilt angle and spot position of the first parallel beam to perform the holographic lithography process for different periods.
9. The apparatus of claim 5 or 6, wherein the first and second single mode fibers are made of fused silica material adapted to transmit the single longitudinal mode blue laser light having a wavelength of 405 nm.
10. The apparatus of claim 1 or 5 or 6,
the collimating lens is a non-spherical biconvex lens with a focal length of 3mm and is made of optical glass, and an antireflection film is plated on the surface of the collimating lens;
the first optical fiber collimating lens and the second optical fiber collimating lens are aspheric biconvex lenses and are made of quartz materials;
the first plano-convex lens is made of optical glass;
the lens group consists of a third fiber collimating lens and a second plano-convex lens, wherein the third fiber collimating lens is close to the second single-mode fiber, and the convex surface of the second plano-convex lens faces the imaging spectrometer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211042313.4A CN115373229A (en) | 2022-08-29 | 2022-08-29 | Device for realizing holographic photoetching by using semiconductor laser |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211042313.4A CN115373229A (en) | 2022-08-29 | 2022-08-29 | Device for realizing holographic photoetching by using semiconductor laser |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115373229A true CN115373229A (en) | 2022-11-22 |
Family
ID=84070052
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211042313.4A Pending CN115373229A (en) | 2022-08-29 | 2022-08-29 | Device for realizing holographic photoetching by using semiconductor laser |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115373229A (en) |
-
2022
- 2022-08-29 CN CN202211042313.4A patent/CN115373229A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Xie et al. | Metasurface-integrated vertical cavity surface-emitting lasers for programmable directional lasing emissions | |
| US8111378B2 (en) | Exposure method and apparatus, and device production method | |
| US7847213B1 (en) | Method and apparatus for modifying an intensity profile of a coherent photonic beam | |
| US20140240951A1 (en) | Systems for Providing Illumination in Optical Metrology | |
| TWI448026B (en) | Method and apparatus for driving semiconductor lasers, and method and apparatus for deriving drive current patterns for semiconductor lasers | |
| US9025133B2 (en) | Laser interference lithography apparatus using fiber as spatial filter and beam expander | |
| JP6879950B2 (en) | Non-linear optical wavelength converter with output scaling | |
| US20120241649A1 (en) | Extreme ultraviolet light generation apparatus and extreme ultraviolet light generation method | |
| KR101345070B1 (en) | Processing substrates using direct and recycled radiation | |
| US20080311531A1 (en) | Method and apparatus for generating periodic patterns by step-and-align interference lithography | |
| TWI245473B (en) | Tunable laser source and wavelength selecting method thereof | |
| US9819150B2 (en) | Surface-emitting ring-cavity quantum cascade laser with ring-shaped phase shifter and related methods | |
| CN109283805A (en) | Laser direct-writing device based on Darman raster | |
| US9904176B2 (en) | Interference lithography device | |
| JP2004072069A (en) | Resonant cavity system of tunable multiple-wavelength semiconductor laser | |
| CN108227063B (en) | Integrated polarization grating preparation system and method | |
| US10101652B2 (en) | Exposure method, method of fabricating periodic microstructure, method of fabricating grid polarizing element and exposure apparatus | |
| WO2004054052A1 (en) | Laser device and wavelength selecting method in laser device | |
| CN115373229A (en) | Device for realizing holographic photoetching by using semiconductor laser | |
| Kolosov et al. | Formation of the feedback loop for phase control of a fiber laser array | |
| US20110304838A1 (en) | Exposure system and adjustment method thereof | |
| JP2006054412A (en) | Wavelength-variable external resonance laser diode using variable optical deflector | |
| JPH075317A (en) | Apparatus and method for manufacture of curved lattice of surface-radiation- distribution-feedback semiconductor laser diode device | |
| CN117970753A (en) | Holographic photoetching device and holographic photoetching method based on semiconductor laser | |
| JP2007027251A (en) | Laser device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |