CN114192987A

CN114192987A - Laser processing apparatus and method

Info

Publication number: CN114192987A
Application number: CN202010911867.8A
Authority: CN
Inventors: 王诗男
Original assignee: Shanghai Industrial Utechnology Research Institute
Current assignee: Shanghai Industrial Utechnology Research Institute
Priority date: 2020-09-02
Filing date: 2020-09-02
Publication date: 2022-03-18

Abstract

The invention discloses a laser processing device and a method, wherein the laser processing device comprises: a laser that emits laser light; an object stage for carrying a substrate; an optical system that guides laser light emitted from the laser to the substrate to irradiate the substrate with a light beam; and a liquid circulation system for supplying a liquid to the processing site of the substrate, and forming a solid-liquid interface between the substrate and the liquid at the processing site of the substrate. The present invention can process a microstructure on a semiconductor substrate with a single laser beam or a plurality of laser beams, respectively, or simultaneously. In the processing process of the microstructure, due to the introduction of the liquid circulation system, the precision and the speed of etching generated on a solid-liquid interface irradiated by laser are stable, and the production adaptability is improved.

Description

Laser processing apparatus and method

Technical Field

The present disclosure relates to the field of micromachining technology, and more particularly, to a laser processing apparatus and method.

Background

In semiconductor devices, in particular Micro Electro Mechanical Systems (MEMS) devices, a fine structure is often required. Sometimes, the fine structure is complicated in shape, including a hollow structure; sometimes, a membrane suspended over the cavity is also required. For example, some pressure sensors require a suspended membrane to be formed over the cavity. For another example, some microfluidic devices require a completely sealed microchannel, except for an inlet and an outlet, where a liquid is introduced at the inlet and discharged at the outlet, and various desired purposes such as detection, screening, mixing, and reaction are achieved in the sealed microchannel between the inlet and the outlet. The microstructure of such a MEMS device is generally complicated, and it is difficult to easily realize the microstructure by a general microfabrication technique. Therefore, the common methods are: a complex, sometimes hermetic, microstructure is achieved by machining a portion of the desired microstructure on one or both major surfaces of a semiconductor substrate and then bonding or bonding the two semiconductor substrates together. Generally, the conventional fine structures are difficult to manufacture, have high production cost, and have limited performance. For example, a fine structure manufactured by bonding or adhering two semiconductor substrates has a complicated process and a high cost; also, a problem of misalignment between patterns may occur during substrate bonding or adhesion. In addition, the semiconductor substrate bonding realized by the bonding glue also avoids the reduction of the dimensional control precision of the fine structure caused by the fact that the bonding glue cannot overflow into the fine structure; the bonding adhesive may be decomposed or dissolved into the fine structure, which may adversely affect the structure. On the other hand, such a fine structure may be formed by a laser processing method. Compared with a photoetching and etching mode, the laser processing mode has certain advantages. Firstly, the laser processing mode has simple device and low manufacturing cost and operation cost; the whole set of devices such as a photomask preparation device, a glue coating and developing device, an exposure device, an etching device, a photoresist removing device and the like are not needed like a photoetching and etching mode. In addition, the processed product of the laser processing method is a raw material of a semiconductor substrate or a thin film formed on the semiconductor substrate, and has little influence on the environment; unlike photolithography and etching, which requires the use of environmentally responsible gases or liquids, the work product is often an environmentally responsible compound. Moreover, the laser processing mode can process relatively flexible patterns and has high degree of freedom. In the laser processing method, there is a method of performing fine processing on a semiconductor substrate by absorbing laser energy with a liquid. However, conventional microfabrication by absorption of laser energy by a liquid is often performed in a laboratory, and the processing accuracy and reproducibility are not sufficient enough for mass production.

Disclosure of Invention

The invention provides a laser processing device and a laser processing method, aiming at overcoming the defect of insufficient precision of substrate processing in the prior art.

The invention solves the technical problems through the following technical scheme:

the invention provides a laser processing device, which comprises a laser and is characterized by also comprising:

an object stage for carrying a substrate;

an optical system that guides laser light emitted from the laser to the substrate to irradiate the substrate with a light beam; and

and a liquid circulation system for supplying a liquid to the processing site of the substrate and forming a solid-liquid interface between the substrate and the liquid at the processing site of the substrate.

Preferably, the liquid circulation system comprises a container, a liquid circulation pump and a conduit; the container holds the objective table, and the container holds liquid, and the both ends of pipe communicate with the container respectively, and liquid circulating pump drive liquid flows from one end of pipe to the other end.

Preferably, the optical system comprises a shaping member and a guiding member for the laser beam,

wherein the shaping component shapes the laser emitted by the laser into a beam with a predetermined spot pattern,

the guide member guides the light beam to the substrate.

Preferably, the guide member comprises a scanning mirror.

Preferably, the device further comprises a driving structure for driving the object stage to move along a preset mode,

the movement in the predetermined manner includes at least one of movement in a horizontal direction, movement in a vertical direction, and rotation in a horizontal direction.

Preferably, a pattern alignment system is further included that aligns the surface of the substrate to be processed with a predetermined pattern.

Preferably, the device further comprises a pattern generating system for forming a processing pattern of the microstructure; and

and a control system for controlling the laser, the stage, the liquid circulation system, and the optical system according to the processing pattern.

Preferably, the laser includes a plurality of laser light emitting sources.

The invention also provides a laser processing method, which comprises the following steps:

emitting laser by a laser;

carrying the substrate by an objective table;

guiding laser light emitted from the laser to the substrate by an optical system, thereby irradiating a beam to the substrate from the front/back side of the substrate;

supplying liquid to the processed part of the substrate by a liquid circulation system so as to form a solid-liquid interface formed by the substrate and the liquid on the processed surface of the substrate;

wherein, the liquid absorbs the laser at the solid-liquid interface to carry out corrosion processing on the processed surface of the substrate;

the laser, the stage, the liquid circulation system, and the optical system are controlled by the control system according to the processing pattern of the microstructure.

Preferably, the processed surface of the substrate is opposite to the incident surface of the laser,

or the processed surface of the substrate is the same as the incident surface of the laser light.

The positive progress effects of the invention are as follows: the invention can process the microstructure on the semiconductor substrate by single laser or multiple laser respectively or simultaneously. In the processing process of the microstructure, due to the introduction of the liquid circulation system, the precision and the speed of etching generated on a solid-liquid interface irradiated by laser are stable, and the production adaptability is improved.

Drawings

Fig. 1 is a schematic structural view of a laser processing apparatus according to embodiment 1 of the present invention.

Fig. 2 is a schematic configuration diagram of a stage of a laser processing apparatus according to embodiment 1 of the present invention.

Fig. 3 is a schematic view of a stage of a laser processing apparatus according to embodiment 1 of the present invention, to which a substrate is fixed.

Fig. 4 is a schematic view of coordinate axes of a laser processing apparatus according to embodiment 1 of the present invention.

Fig. 5 is a schematic view of the coordinate axes of the horizontal plane of the laser processing apparatus according to embodiment 1 of the present invention.

Fig. 6 is a schematic view of a liquid circulation system of a laser processing apparatus according to embodiment 1 of the present invention.

Fig. 7 is a schematic view of a liquid containing system of a liquid circulation system of a laser processing apparatus according to embodiment 1 of the present invention.

Fig. 8 is a schematic view of a holding stage and a liquid of a liquid circulation system of a laser processing apparatus according to embodiment 1 of the present invention.

Fig. 9 is a flowchart of a laser processing method of embodiment 2 of the present invention.

Fig. 10 is a schematic view of a substrate of the laser processing method of embodiment 2 of the present invention.

Fig. 11 is a schematic view of a substrate and a liquid in the laser processing method of embodiment 2 of the present invention.

Fig. 12 is a schematic view of a laser beam irradiated at a solid-liquid interface of a substrate in the laser processing method of embodiment 2 of the present invention.

Fig. 13 is a schematic view of forming a connection portion in the laser processing method of embodiment 2 of the present invention.

Fig. 14 is a schematic view of the laser processing method of embodiment 2 of the present invention, in which the liquid is omitted, for forming the connection portion.

Fig. 15 is a schematic view of forming a minute channel in the laser processing method of example 2 of the present invention.

Fig. 16 is a schematic view of forming projections and depressions by the laser processing method according to embodiment 2 of the present invention.

Fig. 17 is a schematic view of a laser beam irradiated at a solid-liquid interface of a substrate in the laser processing method of embodiment 3 of the present invention.

Fig. 18 is a schematic view of forming a PZT microstructure by the laser processing method of example 3 of the present invention.

Fig. 19 is a schematic view of the laser processing method of example 3 of the present invention, with liquid omitted, for forming a PZT microstructure.

Fig. 20 is a schematic plan view of the PZT microstructure formed by the laser processing method of example 3 of the present invention.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.

Example 1

The present embodiment provides a laser processing apparatus for forming a fine structure on a substrate. Fig. 1 to 3 show a part of the laser processing apparatus of the present embodiment, which includes the most basic components of the laser processing apparatus of the present embodiment, and the laser processing apparatus may further have other components not shown.

In the present embodiment, the substrate to be processed may be a semiconductor substrate or a non-semiconductor substrate, and in the following description of the present embodiment, a semiconductor substrate is taken as an example, but the following description is also applicable to the case where the substrate is a non-semiconductor substrate.

The laser processing apparatus of the present embodiment includes a laser 1, a stage 3 for carrying a substrate 2, an optical system 5 for guiding laser light 4 (or laser beam) emitted from the laser 1 to the substrate, a liquid circulation system 6 for supplying liquid 9 to a processed portion of the substrate and forming a solid-liquid interface formed by the substrate and the liquid 9 at the processed portion, a pattern generating system 7 for forming a processing pattern of a microstructure, and a control system 8 for controlling the laser 1, the stage 3, the optical system 5, and the liquid circulation system 6 in accordance with the processing pattern. As described below, the laser processing apparatus of the present embodiment can perform microfabrication mainly by physical etching of the substrate 2 by absorbing the energy of the laser beam 4 with the liquid 9, and can also be used to perform laser-assisted liquid etching mainly by chemical reaction of the substrate 2.

In an alternative embodiment, the laser 1 has a plurality of laser emitting light sources. That is, the laser 4 has a plurality of beams. According to the processing requirement, the wavelength, the intensity and the waveform of the laser 4 can be reasonably set. The laser 4 may be a continuous wave or a pulsed wave. The wavelength, intensity, waveform, etc. of each laser 4 may be the same as or different from those of the other lasers. Thus, the substrate 2 can be simultaneously processed into a fine structure by the plural laser beams 4.

The substrate 2 may be a wafer commonly used in the field of semiconductor manufacturing, for example, a Silicon wafer, a Silicon On Insulator (SOI) wafer, a Silicon germanium wafer, a gallium nitride wafer, a SiC (Silicon carbide) wafer, or the like, or may be an insulating wafer such as quartz, sapphire, glass, or the like. The substrate 2 may be a wafer commonly used in the semiconductor manufacturing field, and may further include various films and various structures required for a semiconductor device or a MEMS device on the surface of the wafer. The substrate 2 may be a base material made of other materials such as metal, ceramic, and plastic.

The stage 3 is a tool for supporting and fixing a substrate to be processed. The size of the stage 3 matches the size of the substrate, and may correspond to a substrate of a specific size or substrates of various sizes. In an alternative embodiment, the stage 3 fixes the substrate by vacuum adsorption; in another alternative embodiment, the stage 3 fixes the substrate by mechanical fixing; in other alternative embodiments, the stage 3 may be fixed to the substrate by other conventional fixing means. The laser processing device further comprises a driving structure, and the driving structure drives the objective table to move along a preset mode. The stage 3 may be moved in the horizontal and vertical directions or may be rotated in the horizontal direction. Thus, even when the laser beam position is fixed, complicated three-dimensional microstructure processing can be performed on the substrate.

Fig. 2 shows a sectional view of the object table 3 in the vertical direction. The stage 3 includes a stage frame 3a, a semiconductor substrate bearing portion 3b, and a through-hole 3 c. The central axis of the stage 3 in the vertical direction is 3 d. Fig. 3 shows a state after the stage 3 has placed the substrate. The substrate is fixed at the carrying portion 3 b. The first main surface 2a and the second main surface 2b of the substrate after being fixed are exposed from the stage 3 at portions to be processed. As shown in fig. 4, stage 3 can be moved X, Y, Z along three mutually orthogonal principal axes, where O represents the origin of coordinates. For example, the X axis and the Y axis are horizontal, and the Z axis is vertical and coincides with a central axis 3d of the stage 3 in the vertical direction. As shown in fig. 5, the stage 3 may be rotated within a horizontal plane (horizontal direction) formed by the X axis and the Y axis. That is, the stage 3 rotates about the Z axis. The rotation angle θ of the stage 3 may be any angle within 0 to 360 °. The rotation angle theta may also be out of the range of 0-360 deg., i.e. the stage 3 may be rotated continuously or in the opposite direction. The translation of the stage 3 in the X, Y, Z-axis directions and the rotation around the Z-axis are independent of each other, but may be performed simultaneously as necessary.

The optical system 5 is a system for guiding the laser light 4 emitted by the laser 1 to the substrate, and may include a shaping member and a guiding member for the laser beam. In some alternative embodiments, the optical system 5 includes a lens (i.e., a shaping component of the laser beam), an optical waveguide (i.e., a guiding component), and may also include a scanning mirror (i.e., a mirror that can scan) as a guiding mechanism. The scanning mirror is disposed on the optical path and can scan at a predetermined speed and angle. The specific structure of the scanning mirror and the specific arrangement manner of the scanning mirror in the optical system can be realized by those skilled in the art, and are not described herein again. The optical system 5 can shape the laser beam into a desired cross-sectional structure (spot pattern) and guide the laser beam to a substrate to be processed. When the optical system 5 includes a scanning mirror, the laser beam 4 can be moved independently of the substrate, and the degree of freedom of microfabrication is improved. Note that, although fig. 1 shows the optical system 5 guiding the laser light 4 to the front surface (first main surface 2a) of the substrate, the present embodiment is not limited to this, and the optical system 5 may guide the laser light 4 to the front surface and/or the back surface (second main surface 2b) of the substrate, for example: the hollow structure of the stage 3 allows both main surfaces (i.e., the first main surface 2a and the second main surface 2b) of the substrate to be exposed to allow the beams to approach, and the optical system 5 may have a plurality of optical paths in which the laser beams can be guided using optical waveguides as guiding members to guide the laser beams to any one position of the substrate, including to the front and back surfaces of the substrate. In the present embodiment, the optical system 5 guides the laser light 4 to the front surface and/or the back surface of the substrate, respectively, whereby either one or both of the front surface and the back surface of the substrate can be processed. When the lasers are plural, the optical system 5 includes a set of optical paths corresponding to each laser, respectively, so as to guide the beam of each laser to the substrate, respectively. When the laser is one, the laser beam may be split into two or more beams by a beam splitting device, and the optical system 5 includes a plurality of sets of optical paths, and each beam is guided to a desired place through a corresponding set of optical paths. For example, when processing the front and back surfaces of a substrate simultaneously, one set of optical paths directs the beam to the front surface of the substrate and the other set of optical paths directs the beam to the back surface of the substrate.

Referring to fig. 6, the liquid circulation system 6 includes a container 6-1 that can contain a liquid 9, a pipe 6-2, and a liquid circulation pump 6-3. In an alternative embodiment, the liquid circulation system 6 further comprises a liquid temperature control mechanism (not shown in the figures). The liquid temperature control mechanism includes a heating device, a temperature measuring device, etc. The specific setting manner of the liquid temperature control mechanism can be realized by those skilled in the art, and is not described herein again.

In an alternative embodiment, the liquid circulation system 6 further comprises a valve (not shown in the figures). The specific arrangement of the valve is realized by those skilled in the art, and will not be described herein. In another alternative embodiment, fluid circulation system 6 does not include a valve.

In an alternative embodiment, the liquid circulation system 6 comprises a level gauge (not shown in the figures). The specific arrangement of the liquid level gauge is realized by those skilled in the art, and will not be described herein. In another alternative embodiment, the liquid circulation system 6 does not include a level gauge.

As shown in FIG. 6, the container 6-1 of the liquid circulation system 6 is free of liquid 9; as shown in fig. 7, a liquid 9 is filled in a container 6-1 of the liquid circulation system 6. The liquid circulation pump 6-3 drives the liquid 9 in the pipe 6-2 in the direction indicated by the arrow to effect circulation of the liquid 9 in the vessel 6-1.

As shown in fig. 8, the container 6-1 of the liquid circulation system 6 accommodates the stage 3, and the substrate 2 is fixed to the upper surface of the stage 3. The stage 3 on which the substrate 2 is fixed can be moved and rotated in the container 6-1. The surface of the liquid 9 may be higher than the second main surface 2b of the substrate or lower than the second main surface 2b of the substrate. The circulation direction (the direction indicated by the arrow in the figure) and the circulation speed of the liquid 9 in the container 6-1 can be changed under the driving of the liquid circulation pump 6-3; the liquid 9 in the container 6-1 may also be stationary. The liquid 9 controlled by the liquid circulation system 6 can form a solid-liquid interface 10 formed by the substrate 2 and the liquid 9 at the processing site of the substrate 2. The circulation of the liquid 9 by the liquid circulation pump 6-3 can also timely carry the products (chips or chemical reaction products) away from the processed part during the fine processing of the substrate 2, so that the processing can be continuously and stably carried out.

The pattern generation system 7 is used to generate electronic information of a processing pattern of a microstructure to be processed. The graphics generation system 7 may include a computer and drawing software. The electronic information of the processed pattern may contain information such as the size and layout of the microstructure. For example, the graphic generation system 7 may generate electronic information of a three-dimensional processed graphic by drawing, or may generate electronic information of a three-dimensional processed graphic by inputting coordinates.

The control system 8 controls the laser 1, the stage 3, the optical system 5, and the liquid circulation system 6 according to the processing pattern. The control system 8 is realized by a computer, and control software is operated to realize corresponding control. In an alternative embodiment, the control system 8 and the graphics-generating system 7 may share a single controller (e.g., a computer), i.e., the control system 8 and the graphics-generating system 7 are implemented on the same controller. In another alternative embodiment, control system 8 is implemented using a different controller than graphics-generation system 7.

The control of the laser 1 by the control system 8 includes controlling the laser 1 on and off, intensity, waveform, etc. The control system 8 controls the stage 3, including controlling the distance and speed of movement of the stage 3 in the horizontal and vertical directions, and the angle and speed of rotation in the horizontal direction. The control of the optical system 5 by the control system 8 includes controlling the optical system 5 to adjust the cross-sectional structure of the laser beam 4, scanning the laser beam 4, and changing the focal point of the laser beam 4. When the optical system 5 includes a scanning mirror, the control optical system 5 can control the scanning range, the scanning speed, and the like of the laser light 4. The control of the liquid circulation system 6 by the control system 8 may include controlling the level of the liquid 9 in the vessel 6-1, the speed and direction of operation of the liquid circulation pump 6-3 (i.e., the direction and speed of circulation of the liquid 9 in the vessel 6-1).

As an alternative embodiment, the laser machining apparatus further comprises a pattern alignment system. The pattern alignment system comprises a pattern alignment mark detection mechanism and an alignment mechanism. When the fine structure processing is required to be performed on both main surfaces of the substrate, respectively, or simultaneously, the pattern alignment system may perform the pattern alignment on both main surfaces of the substrate, respectively, or simultaneously.

When the substrate is fixed on the stage 3, the portions of the first main surface 2a and the second main surface 2b of the substrate to be processed are exposed. Therefore, the laser processing apparatus can process the microstructure on the first main surface 2a and the second main surface 2b of the substrate separately or simultaneously. Further, when the substrate is fixed on the stage 3 and placed in the container 6-1 of the liquid circulation system filled with the liquid 9, a solid-liquid interface 10 formed by the substrate 2 and the liquid 9 is formed at the surface to be processed of the substrate 2. When the laser light 4 is irradiated to the solid-liquid interface 10, microfabrication of the substrate 2 can be achieved by two principles. The first principle is a biased physical engraving. That is, the substrate 2 is almost transparent to the laser beam 4, and the energy of the laser beam 4 is absorbed by the liquid 9, so that a high-temperature and high-pressure local shock wave is generated at the solid-liquid interface 10 to which the laser beam is irradiated, and the substrate 2 is processed. The second principle is a more chemical corrosion. That is, the energy of the laser beam 4 is absorbed by the substrate 2, not almost by the liquid 9, and local high temperature is generated at the solid-liquid interface 10 irradiated with the laser beam, or the material of the substrate 2 is activated or dissociated, so that the rate of the chemical reaction between the substrate 2 and the liquid 9 is remarkably increased, and the purpose of finely processing the substrate 2 is achieved. In both cases, the precision, rate, and other processing results of the microfabrication by engraving or etching (collectively referred to as etching) are determined by the processing conditions such as the wavelength of the laser beam 4, the spot size, the irradiation energy, the dwell time of the beam, the material of the substrate 2, and the composition, concentration, temperature, and circulation rate of the liquid 9. Fig. 8 illustrates an example of processing a microstructure on the first main surface 2 a. The method of processing the microstructure on the second main surface 2b also having the solid-liquid surface and simultaneously processing the microstructure on the first main surface 2a and the second main surface 2b both having the solid-liquid surface is the same as in the above-described embodiment, and will not be described in detail hereinafter.

As described above, the present embodiment provides a laser processing apparatus capable of processing a fine structure on a semiconductor substrate with a single laser beam or a plurality of laser beams, respectively, or simultaneously. In the processing process of the microstructure, due to the introduction of the liquid circulation system, the precision and the speed of etching generated on a solid-liquid interface irradiated by laser are stable, and the production adaptability of the laser processing system is improved.

Example 2

The present embodiment provides a laser processing method. In an alternative embodiment, the laser machining method is implemented using the laser machining apparatus of example 1 to perform fine structure machining. Referring to fig. 9, the laser processing method of the present embodiment includes the steps of:

step S301, a substrate is prepared.

Step S302, the substrate is fixed on the stage.

Step S303 is to place the stage to which the substrate is fixed in a container of a liquid circulation system filled with liquid, so that a solid-liquid interface is formed between the liquid and the portion to be processed of the surface to be processed of the substrate.

Step S304, irradiating the solid-liquid interface of the substrate with laser beams, and etching the processed part of the substrate to form a target pattern.

As an example, referring to fig. 10 to 15, the present embodiment has been described taking as an example the case where processing is performed from the first main surface 2a side of the substrate 2 by a laser processing method to form the minute channel 12 inside the substrate 2. Fig. 10-15 are cross-sectional views illustrating the processing method.

As shown in fig. 10, in step S301, the substrate 2 is prepared. As an example, the substrate 2 is a quartz wafer, for example, having a thickness of about 725 microns and a diameter of about 200 mm. Other types of wafers may be processed using similar principles as described below. The substrate 2 has two main surfaces parallel to each other, namely a first main surface 2a and a second main surface 2 b.

Then, in step S302, referring to fig. 3, the substrate 2 is fixed on the stage 3. Then, in step S303, referring to fig. 8, the stage 3 to which the substrate 2 is fixed is placed in the container 6-1 of the liquid circulation system filled with the liquid 9, and the portion to be processed of the first main surface 2a of the substrate 2 and the liquid 9 form the solid-liquid interface 10. The liquid 9 is controlled at a certain temperature by the liquid circulation system 6 and circulated at a certain speed in the container 6-1. For simplicity, only the substrate 2 and the liquid 9 are shown in fig. 11. As an alternative embodiment, the liquid 9 consists of a pigment and a solvent.

Then, in step S304, referring to fig. 12, the solid-liquid interface 10 of the substrate 2 to be processed is irradiated with the laser beam 4, and the corresponding portion of the substrate 2 is etched. When the micromachining starts from the first main surface 2a of the substrate 2, the laser light 4 is irradiated from the second main surface 2b opposed to the first main surface 2a of the substrate 2. The laser 4 is controlled by the control system 8 according to the processing pattern, and can be correspondingly scanned according to the designed pattern and the etching program. The wavelength, energy, waveform, and the like of the laser light 4 are selected as necessary. The laser light 4 is substantially transparent to the substrate 2. That is, the laser light 4 may pass through the inside of the substrate 2 without being substantially absorbed. The laser 4 may be a pulsed laser or a continuous laser. For example, when the substrate 2 is made of quartz, the laser 4 is a nanosecond-level pulse laser having an ultraviolet wavelength (KrF) and has an energy density>0.1 Joule/cm²(square centimeter). The liquid 9 absorbs the laser energy of the laser beam 4, and generates a high-temperature, high-pressure local shock wave at the solid-liquid interface 10. Such local shock waves perform bombardment processing (also referred to as etching) with nanometer accuracy on the surface of the substrate 2 at the solid-liquid interface 10 at nanosecond-level instants. The part of the substrate 2 etched away is suspended in the form of fine particlesThe liquid 9 is carried away and removed by the circulation of the liquid 9. The composition and concentration of the liquid 9 can be optimally adjusted to achieve a desired etching rate and accuracy. The higher the absorption capability of the liquid 9 for the energy of the laser light 4, the faster the speed of the microfabrication. After the surface of the substrate 2 at the solid-liquid interface 10 is etched, the liquid 9 automatically flows to the newly formed surface of the substrate 2 to form a new solid-liquid interface 10, and the etching can be continuously performed in the inner direction of the substrate 2. By controlling the scanning of the laser 4 in accordance with a designed pattern and an etching program, the opening 11a and the connecting portion 11c can be formed.

Then, as shown in fig. 13, the micro-vias 12 are machined according to the principles described above. As the processing proceeds, new solid-liquid interfaces 10 are continuously formed, so that the minute channels 12 (or cavities) can be processed and formed inside the substrate 2. The laser processing of the microchannel 12 may be gradually moved from a direction close to the first main surface 2a of the substrate 2 toward the second main surface 2b of the substrate 2. To assist understanding, fig. 14 shows the state where the laser 4 and the liquid 9 are removed. It can be seen that the above-described mode of performing microfabrication by absorbing laser light at the solid-liquid interface 10 can form not only a fine pattern (for example, the opening 11a and the connecting portion 11c) in the vicinity of the surface of the substrate 2 but also a fine structure sealed in the substrate 2 such as the microchannel 12 by performing microfabrication with a high degree of freedom in the interior of the substrate 2. Obviously, the fine processing of the opening 11a and the connecting portion 11c may be performed by conventional fine processing methods of other methods. However, the micro-vias 12 are difficult to be machined by other conventional methods.

Then, as shown in fig. 15, by continuing the laser micromachining in accordance with the above-described principle, a microstructure including the opening 11 (including 11a and 11b), the connecting portion 11c, and the minute channel 12 formed on the substrate 2 can be obtained. If necessary, a protective layer (not shown) or a thin film (not shown) having a function such as hydrophilicity or hydrophobicity may be formed on the side wall of the microchannel 12. For example, an alumina film may be formed on the side wall of the micro-channel 12 by Atomic Layer Deposition (ALD). For another example, a thin film having functions such as hydrophilicity and hydrophobicity may be formed on the side wall of the microchannel 12 by a liquid or gaseous film formation method.

As an alternative embodiment, referring to fig. 16, various minute structures such as projections 12a, depressions 12b, and the like may be formed on the side wall of the minute channel 12 separately or simultaneously as necessary in accordance with the foregoing principle.

It is apparent that the laser processing method of the present embodiment can obtain a fine structure with a high degree of freedom of shape on the substrate 2. For example, each opening 11 may correspond to one or a plurality of microchannels 12. Also, each minute channel 12 may correspond to 1 or a plurality of openings 11. The shapes and sizes of the opening 11, the connecting portion 11c, and the minute passage (or cavity) 12 can be designed and manufactured with a high degree of freedom. For example, the above-described fine structure can be designed and manufactured to meet the requirements of various microfluidic devices. For example, the fine structure may be designed and manufactured as required for the pressure sensor. For the pressure sensor, specifically, the minute channel 12 may be a cavity having a designed shape, area and height, and the floating portion 13 of the semiconductor substrate above the minute channel (or cavity) 12 may be a floating film having a designed shape, area and thickness.

The method of processing the microstructure on the second main surface 2b also having the solid-liquid surface and simultaneously processing the microstructure on the first main surface 2a and the second main surface 2b both having the solid-liquid surface is the same as in the above-described embodiment, and will not be described in detail hereinafter.

As described above, the laser processing method of the present embodiment provides a processing method for forming a minute channel (or cavity) inside a semiconductor substrate, which can obtain a minute structure with a high degree of freedom in shape and size. The processing method has simple procedures and easy implementation, and can reduce the manufacturing cost. Meanwhile, the defects that position deviation is easy to generate due to bonding and the like and foreign matters such as bonding glue exist in a micro channel do not exist, and the size precision and the performance of the micro structure can be improved.

Example 3

The present embodiment provides a laser processing method. In an alternative embodiment, the laser machining method is implemented using the laser machining apparatus of example 1 to perform fine structure machining. The flow of the laser processing method of the present embodiment is substantially the same as the flow of the laser processing method of embodiment 2.

As an example, referring to fig. 17 to 20, the present embodiment has been described taking as an example the case where the laser processing method is used to perform processing from the first main surface 2a side of the substrate 2 to form a fine pattern on the surface of the substrate 2. Fig. 17 to 19 are sectional views illustrating the laser processing method, and fig. 20 is a plan view illustrating the laser processing method.

As shown in fig. 10, in step S301, the substrate 2 is prepared. As an example, the substrate 2 is a piezoelectric ceramic PZT (lead zirconate titanate) thin plate, for example, having a thickness of about 500 μm and a length and width of about 100 mm. The substrate 2 has two main surfaces parallel to each other, namely a first main surface 2a and a second main surface 2 b.

Then, in step S302, referring to fig. 3, the substrate 2 is fixed on the stage 3. Then, in step S303, referring to fig. 8, the stage 3 to which the substrate 2 is fixed is placed in the container 6-1 of the liquid circulation system filled with the liquid 9, and the portion to be processed of the first main surface 2a of the substrate 2 and the liquid 9 form the solid-liquid interface 10. A special example is to immerse the first main surface 2a of the substrate 2 completely within the liquid 9. The liquid 9 is controlled at a certain temperature by the liquid circulation system 6 and circulated at a certain speed in the container 6-1. For simplicity, only the substrate 2 and the liquid 9 are shown in fig. 11. As an alternative embodiment, the liquid 9 is a solution of KOH.

Then, in step S304, referring to fig. 17, the solid-liquid interface 10 of the substrate 2 to be processed is irradiated with the laser beam 4, and the corresponding portion of the substrate 2 is etched. When the liquid 9 is a KOH solution, the PZT substrate is slightly corroded in a short time even if immersed in KOH at a temperature near room temperature. The laser was controlled in the same manner as in example 2. For example, the laser 4 is a continuous laser emitted by an Ar laser, the spot diameter irradiated to the solid-liquid interface 10 is 15 microns, and the laser energy density is 105-107W/cm². Meanwhile, KOH is substantially transparent to Ar laser light. Base plate 2 pair composed of PZTAnd opaque to Ar laser 4. That is, the laser light 4 is substantially absorbed at the surface of the substrate 2. The laser beam 4 is incident on the solid-liquid interface 10 formed by the PZT substrate 2 and KOH via the liquid 9, and the PZT substrate 2 at this position absorbs the laser beam, generates a local high temperature in a very short time, and undergoes a local chemical reaction with the liquid 9. As a result, the portion of the PZT substrate 2 irradiated with the laser beam 4 is etched and dissolved in the KOH solution, and a fine pattern formed by etching is formed on the surface of the PZT substrate 2. After the surface of the substrate 2 at the solid-liquid interface 10 is etched, the liquid 9 automatically flows to the newly formed surface of the substrate 2 to form a new solid-liquid interface 10, and the etching can be continuously performed in the depth direction of the substrate 2. By controlling the scanning of the laser 4 in accordance with the designed pattern and etching program, the PZT microstructure 14 shown in fig. 18 can be formed. To assist understanding, fig. 19 shows the state in which the liquid 9 is removed, and fig. 20 shows a plan view of the substrate 2 in the state of fig. 18, in which the mark 14 represents the PZT microstructure formed by etching, the mark 15 represents the portion of the substrate on the first main surface 2a that is not etched, and the PZT microstructure 14 and the portion 15 that is not etched constitute the target pattern. As can be seen, the above-described mode of performing the micromachining by absorbing the laser beam at the solid-liquid interface 10 enables formation of a desired fine pattern on the surface of the substrate 2. It is obvious that the above processing method can obtain a fine structure with high processing accuracy and high degree of freedom in shape on the substrate 2.

As described above, the laser processing method of the present embodiment provides a processing method for forming a fine structure on the surface of a semiconductor substrate, and can obtain a fine structure having a high degree of freedom in shape and size. The processing method has simple procedures, is easy to implement, can reduce the manufacturing cost, and is suitable for mass production.

While specific embodiments of the invention have been described above, it will be appreciated by those skilled in the art that this is by way of example only, and that the scope of the invention is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the spirit and scope of the invention, and these changes and modifications are within the scope of the invention.

Claims

1. A laser processing apparatus includes a laser which emits laser light, and is characterized by further including:

an object stage for carrying a substrate;

an optical system that guides laser light emitted from the laser to the substrate, thereby irradiating the substrate with a light beam; and

and a liquid circulation system that supplies a liquid to the processing site of the substrate, and forms a solid-liquid interface between the substrate and the liquid at the processing site of the substrate.

2. The laser machining apparatus of claim 1, wherein the liquid circulation system includes a vessel, a liquid circulation pump, a conduit; the container contains the objective table, the container contains the liquid, two ends of the guide pipe are respectively communicated with the container, and the liquid circulating pump drives the liquid to flow from one end of the guide pipe to the other end of the guide pipe.

3. Laser machining device according to claim 1, characterized in that the optical system comprises a shaping member and a guiding member for the laser beam,

wherein the shaping part shapes the laser light emitted from the laser into a beam having a predetermined spot pattern,

the guide member guides the light beam to the substrate.

4. The laser machining apparatus of claim 3, wherein the guide member includes a scanning mirror.

5. The laser processing apparatus according to claim 1, further comprising a driving mechanism that drives the stage to move in a predetermined manner,

the moving in the preset manner includes at least one of moving in a horizontal direction, moving in a vertical direction, and rotating in a horizontal direction.

6. The laser processing apparatus of claim 1, further comprising a pattern alignment system that aligns the surface of the substrate to be processed with a predetermined pattern.

7. The laser processing apparatus according to claim 1, further comprising a pattern generating system that forms a processing pattern of the microstructure; and

a control system that controls the laser, the stage, the liquid circulation system, and the optical system according to the processing pattern.

8. The laser processing apparatus of claim 1, wherein the laser comprises a plurality of laser emitting light sources.

9. A laser processing method, comprising:

emitting laser by a laser;

carrying the substrate by an objective table;

directing laser light emitted from the laser to the substrate by an optical system, thereby irradiating a beam from the front/back surface of the substrate to the substrate;

providing liquid to the processed part of the substrate by a liquid circulation system so as to form a solid-liquid interface formed by the substrate and the liquid on the processed surface of the substrate;

wherein the liquid absorbs the laser light at the solid-liquid interface to perform etching processing on the processed surface of the substrate;

the laser, the stage, the liquid circulation system, and the optical system are controlled by a control system according to a processing pattern of the microstructure.

10. The laser processing method according to claim 9, wherein the processed surface of the substrate is opposite to an incident surface of the laser light,