CN117051363A - Method for enhancing yield of solid target atoms sputtered by gas cluster ion beam - Google Patents
Method for enhancing yield of solid target atoms sputtered by gas cluster ion beam Download PDFInfo
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Classifications
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/34—Sputtering
- C23C14/3435—Applying energy to the substrate during sputtering
- C23C14/3442—Applying energy to the substrate during sputtering using an ion beam
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
- C23C14/14—Metallic material, boron or silicon
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/34—Sputtering
- C23C14/3407—Cathode assembly for sputtering apparatus, e.g. Target
- C23C14/3414—Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
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Abstract
The invention belongs to the technical field of cluster ion sources and cluster ion beams, and discloses a method for enhancing the atomic yield of a solid target sputtered by a gas cluster ion beam. According to the method for improving the sputtering yield of the solid target atoms, when the energy of clusters is low, the effective size effect of nano particles in the target causes the significant improvement of the sputtering yield; fragments formed in the process of bombarding the target by cluster ions are beneficial to the increase of sputtering yield when the cluster energy is higher; the number of the incident cluster beams is given by a beam integrator, so that the cluster ion beam sputtering parameters of the solid Si powder die-casting target are accurately controllable, and the sputtering yield caused by cluster sputtering is high; compared with a bulk monocrystalline silicon target, the ultra-fine Si powder is adopted as a sputtering target, so that the yield of sputtered Si atoms is remarkably improved.
Description
Technical Field
The invention belongs to the technical field of cluster ion sources and cluster ion beams, and particularly relates to a method for enhancing the yield of solid target atoms sputtered by a gas cluster ion beam.
Background
Currently, a gas cluster is a large particle or polymer thereof with a molecular scale that contains hundreds or thousands of gas molecules. A common method of generating gas clusters is by ultrasonically adiabatic expansion of a quantity of gas or gas mixture through a nozzle. The interactions of gas clusters with the solid surface are very different compared to single atom or molecular beams. Early gas clusters were used to perform micromachining and surface planarization of material surfaces. Since the 1995 Yamada's group of university of kyoto, japan introduced a practical Gas Cluster Ion Beam (GCIB) technology for surface treatment of crystalline silicon and metallic materials, it has been found that GCIB has a highly efficient sputtering effect on solid matter surface atoms with a sputtering yield 2 to 3 orders of magnitude higher than that of a single ion beam.
Because of the large number of atoms in the cluster beam, each atom has low energy calculated by the energy sharing principle, which results in a shallow depth of the cluster atoms into the target, and therefore the cluster beam energy is almost entirely dissipated in a limited area of the target surface. Based on this theory, the energy density and temperature in these impact zones can produce efficient sputtering of the target. GCIB bombards the target material as compared to a single ion beam by generating a high amount of secondary cluster ions. Molecular dynamics simulations and experiments have demonstrated that bombarding a target with a cluster ion beam consisting of 10 argon (Ar) atoms can form an effective solid cluster beam with a very small probability of forming nano-sized secondary particles.
For low-dimensional material systems such as nano particles and nano wires, when the energy-carrying cluster beams interact with the material systems, the energy dissipation is concentrated on a surface localization scale due to a limited size effect, the energy density is high, the sputtering yield of a target is increased sharply, and even the target can be decomposed. Molecular dynamics simulation has been found by researchers to produce ion bombardment of gold particles of several nanometers in diameter, with sputter yields ranging from several atoms to complete decomposition of gold nanotargets, indicating that bombardment of nanosized solid-state targets by an energy-bearing ion beam may produce a cluster beam. Ilinov et al experimentally irradiated gold nanowires of 20nm diameter and micron length with a cluster ion beam having an energy of 80keV and each cluster containing 100-1900 xenon (Xe) atoms, and found that the bombardment of one-dimensional nanowire material by the cluster ion beam increased the sputter atomic yield. However, the relationship between cluster beam energy and sputter target microstructure has not been systematically studied.
It is well known that the sputter yield of target atoms in vacuum sputter coating and secondary ion mass spectrometry devices is an important technological parameter, and that it is a commonly employed method to enhance sputtering by increasing the energy or plasma density of the incident ion beam. In addition, solid state ion sources such as cesium sputter negative ion sources, solid state electrolyte ion sources, and the like, use sputter cathode targets to generate ion beams, the ion beam intensity being dependent on the input beam energy and sputter yield. If the gas cluster ion beam is used as an incident beam, the high sputtering rate of atoms on the surface of the material can be realized based on the energy sharing principle, and the size of the atoms in the sputtering target is controlled to be in the nanometer scale based on the effective size effect, and the combination of the gas cluster ion beam and the sputtering target is an effective technical method for further improving the sputtering yield of the target.
Through the above analysis, the problems and defects existing in the prior art are as follows: related technical schemes for the relation between cluster beam energy and sputtering target microstructure in the prior art have not been reported yet.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a method for enhancing the yield of solid target atoms sputtered by a gas cluster ion beam.
The invention is realized in that a method for enhancing the atomic yield of a solid target by using a gas cluster ion beam comprises the following steps: ar gas cluster ion beams with determined sizes and nano silicon (Si) powder die-casting targets, wherein the Ar gas cluster ion beams bombard the nano Si powder die-casting targets, and part of Si nano particles generated by sputtering are captured by a collector.
Further, the manufacturing method of the nano Si powder die-casting target comprises grinding and hydroforming.
Further, the grinding in the manufacturing method of the nano Si powder die-casting target comprises the following steps: grinding the purchased scientific grade nano Si powder with the average particle size of 30nm into superfine powder with the average particle size of 12-15 nm.
Further, the hydroforming in the manufacturing method of the nano Si powder die-casting target comprises the following steps: the milled Si powder was processed by a hydraulic tablet press under a pressure of 6MPa for 15min.
Further, the method for enhancing the atomic yield of the gas cluster ion beam sputtered solid target comprises the following steps:
step one, a neutral Ar gas cluster beam is generated. Opening a main argon filling valve of a steel cylinder, adjusting a pressure reducing valve to 0.2-0.5 MPa, introducing Ar gas into an ion source cavity of a gas cluster through a pressure-resistant gas conduit, and then entering a differential vacuum chamber of 0.01-0.1 Pa through a Laval ultrasonic nozzle, wherein the gas is subjected to ultrasonic adiabatic expansion to form neutral cluster beams containing thousands to tens of thousands of Ar atoms. (the main pump of the differential vacuum system is a compound turbomolecular pump with a pumping speed of 2500l/s, and the key point for forming neutral gas cluster beams is several atmospheres (2-5×10) 5 Pa) is fed into 10 through a nozzle having a small aperture (central aperture of about 0.1 mm) -2 ～10 -1 The vacuum environment of Pa is formed by adiabatic expansion, and the gas speed reaches supersonic speed level. )
And secondly, the accelerated cathode filament electrons collide and ionize, so that Ar cluster beams become cluster ion beams. The neutral Ar cluster beam advances along the central axis of the pipeline through the adjustment of the four-dimensional collimator, and after the electrons emitted by the cathode filament collide, a small part of clusters are ionized into Ar cluster ion beams.
Step three, the cluster ion beam becomes an energy-carrying cluster ion beam after passing through an accelerating electric field. And in the second step, direct-current high voltage is applied to the pipeline space behind the cathode filament, so that higher incident energy is given to the Ar cluster ion beam.
Further, in the first step, in order to screen the number of Ar atoms in Ar clusters, the cluster ion beam after the acceleration of the electric field is passed through a velocity selector (velocityselector) to determine the velocity v of the cluster beam, and then according to qU =1/2 mv 2 (where q is the effective charge number of the cluster ion beam, can be determined byThe beam integrator gives directly) the mass m of the individual cluster beam. And (3) providing an effective experimental parameter characteristic value, wherein the Ar cluster beam contains N=2900 Ar atoms, the effective charge number q after ionization is 3.45, and the Ar cluster ion beam characteristic parameter relation of N/q=840 is satisfied.
Further, in the second step, the electron voltage of the cathode filament was 150V and the electron emission current was 20mA.
Further, in the third step, the electric field U applied to the cluster ion beam is set to 3-20 kV, and the energy distribution is 10.4-69 keV; monitoring the incidence dose of the cluster beam by a beam integrator to be 5.8X10 15 clusters/cm 2 。
It is a further object of the present invention to provide a computer device comprising a memory and a processor, the memory storing a computer program which, when executed by the processor, causes the processor to perform the steps of the method of enhancing the atomic yield of a gas cluster ion beam sputtered solid target.
It is another object of the present invention to provide a computer readable storage medium storing a computer program which, when executed by a processor, causes the processor to perform the steps of the method of enhancing the atomic yield of a gas cluster ion beam sputtered solid target.
In combination with the technical scheme and the technical problems to be solved, the technical scheme to be protected has the following advantages and positive effects:
first, aiming at the technical problems in the prior art and the difficulty of solving the problems, the technical problems solved by the technical proposal of the invention are analyzed in detail and deeply by tightly combining the technical proposal to be protected, the results and data in the research and development process, and the like, and some technical effects brought after the problems are solved have creative technical effects. The specific description is as follows:
the invention provides a method for improving the sputtering yield of solid target atoms, which has the advantages that: (1) The size and the injection dosage of Ar gas clusters are controllable, the number and the dosage of incident cluster beams can be given by a speed selector and a beam integrator, so that the cluster ion beam sputtering parameters of the solid Si powder die-casting target are precisely controllable, and the sputtering yield caused by cluster sputtering is high; (2) Compared with a bulk monocrystalline silicon target, the ultra-fine Si powder is adopted as a sputtering target, so that the yield of sputtered Si atoms is remarkably improved.
Secondly, the technical scheme is regarded as a whole or from the perspective of products, and the technical scheme to be protected has the following technical effects and advantages:
the present invention provides a method for enhancing the atomic yield of a gas-cluster ion sputter target, comprising two enhancement mechanisms, namely the effective size effect of the low energy region and the fragment enhancement sputter effect of the formation of the high energy region. At lower cluster energies, the effective size effect of the nanoparticles in the target results in a significant increase in sputtered atom yield; at higher cluster energies, fragments formed during the bombardment of the target by the cluster ions contribute to an increase in sputter yield.
Thirdly, as inventive supplementary evidence of the claims of the present invention, the following important aspects are also presented:
(1) The expected benefits and commercial values after the technical scheme of the invention is converted are as follows:
the gas cluster ion beam equipment is a sharp tool for realizing ultra-shallow junction ion implantation and substrate surface treatment in the semiconductor industry, is a core device for material surface analysis in an ultra-high vacuum environment, and is semiconductor commercial equipment which has mass production in countries such as America, japanese and the like. Our country has been studied earlier in this area, but key equipment and technology have not formed an effective competitive situation in the market. In recent years, the chip industry is developed in China, the research and development of domestic cluster ion beam equipment is a necessary trend, and in the early stage, we have obtained patent authorization of the device principle model machine. The application is directed to the technical application of improving the sputtering rate of the solid target material when the solid target material is sputtered by using the cluster ion beam, and has potential application value.
(2) The technical scheme of the invention fills the technical blank in the domestic and foreign industries:
the gas cluster ion beam is used for bombarding the nano-size target material to improve the sputtering rate and explain the physical mechanism of the target material, which is a breakthrough in the application of the domestic cluster ion beam technology, and provides a direct reference value for solving the technical application level that the industrial cluster ion source generates low-energy large-beam cluster ion beam sputtering to generate high-yield solid atomic rate, and no relevant report is provided at home at present.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for enhancing the atomic yield of a gas cluster ion beam sputtered solid target provided by an embodiment of the present invention;
FIG. 2 is a schematic diagram of a gas cluster sputtering nano Si target provided by an embodiment of the present invention;
FIG. 3 is a schematic diagram of sputter yields of a nano Si powder die-cast target and a bulk Si target provided by an embodiment of the present invention under different cluster ion beam energies;
FIG. 4 is a TEM image of a sputter-generated deposit on a collector surface at different cluster energies provided by an embodiment of the present invention;
FIG. 5 is a schematic diagram of the relationship between the nano Si particle size and the number of Si atoms produced by sputtering in a target provided by an embodiment of the present invention;
in the figure: 1. an Ar gas cluster ion beam; 2. die casting a nano Si powder target; 3. sputtering Si nanoparticles; 4. a collector.
Detailed Description
The present invention will be described in further detail with reference to the following examples in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
In view of the problems of the prior art, the present invention provides a method for enhancing the atomic yield of a gas cluster ion beam sputtered solid target, which is described in detail below with reference to the accompanying drawings.
1. The embodiments are explained. In order to fully understand how the invention may be embodied by those skilled in the art, this section is an illustrative embodiment in which the claims are presented for purposes of illustration.
An object of an embodiment of the present invention is to provide a method for enhancing the yield of solid target atoms sputtered by a gas cluster ion beam, wherein a gas cluster Ar is generated by a gas cluster beam apparatus (a gas cluster ion source generating method and apparatus, 2017106649103) 2900 The electron beam impact ionization is carried out to form Ar cluster ion beams, the energy distribution is 10.4-69 keV under an accelerating electric field, and the sputtering mechanism of the increase of Si atom yield in different energy sections is found to be different from that of the die-casting Si powder target with the average size of 12nm.
As shown in fig. 1, the method for enhancing the atomic yield of a solid target by gas cluster ion beam sputtering provided by the embodiment of the invention comprises the following steps:
s101, generating neutral Ar gas cluster beams;
s102, enabling Ar cluster beams to be cluster ion beams through collision ionization of electrons of an accelerated cathode filament;
s103, the cluster ion beam becomes an energy-carrying cluster ion beam after the cluster ion beam is subjected to an accelerating electric field.
In step S101, a neutral Ar gas cluster beam is generated. Opening a main argon filling valve of a steel cylinder, adjusting a pressure reducing valve to 0.2-0.5 MPa, introducing Ar gas into an ion source cavity of a gas cluster through a pressure-resistant gas conduit, and then entering a differential vacuum chamber of 0.01-0.1 Pa through a Laval ultrasonic nozzle, wherein the gas is subjected to ultrasonic adiabatic expansion to form neutral cluster beams containing thousands to tens of thousands of Ar atoms. (the main pump of the differential vacuum system is a compound turbomolecular pump with a pumping speed of 2500l/s, and the key point for forming neutral gas cluster beams is several atmospheres (2-5×10) 5 Pa) is fed into 10 through a nozzle having a small aperture (central aperture of about 0.1 mm) -2 ～10 -1 The vacuum environment of Pa is formed by adiabatic expansion, and the gas speed reaches supersonic speed level. )
In step S102, the accelerated cathode filament electrons impact ionization, so that the Ar cluster beam becomes a cluster ion beam. The neutral Ar cluster beam advances along the central axis of the pipeline through the adjustment of the four-dimensional collimator, and after the electrons emitted by the cathode filament collide, a small part of clusters are ionized into Ar cluster ion beams.
In step S103, the cluster ion beam is subjected to an accelerating electric field to become an energy-carrying cluster ion beam. And in the second step, direct-current high voltage is applied to the pipeline space behind the cathode filament, so that higher incident energy is given to the Ar cluster ion beam.
In step S101, in order to screen the number of Ar atoms in the Ar cluster, the cluster ion beam after the acceleration of the electric field is passed through a velocity selector (velocityselector) to determine the velocity v of the cluster beam, and then according to qU =1/2 mv 2 (where q is the effective charge number of the cluster ion beam, which can be directly given by the beam integrator) the mass m of the individual cluster beam. And (3) providing an effective experimental parameter characteristic value, wherein the Ar cluster beam contains N=2900 Ar atoms, the effective charge number q after ionization is 3.45, and the Ar cluster ion beam characteristic parameter relation of N/q=840 is satisfied.
As shown in fig. 2, the method for enhancing the Si atom yield of the Si nano target sputtering by using the Ar gas cluster ion beam provided by the embodiment of the invention comprises the steps of determining the size of the Ar gas cluster ion beam (1) and the nano Si powder die-casting target (2); wherein Ar gas cluster ion beams (1) bombard the nano Si powder die-casting target (2), and part of Si nano particles (3) generated by sputtering are captured by a collector (4).
The embodiment of the invention provides a large-size gas cluster beam, which comprises characteristic parameters of the gas cluster beam, electron current and voltage for ionization, acceleration field voltage and average size of Si nano particles of a die-casting Si powder target.
In order to achieve a better sputtering effect, each Ar cluster beam contains 2900 Ar atoms, the effective charge number after ionization is 3.45, and the characteristic parameter relation of the Ar cluster beam of N/q=840 is satisfied.
To make Ar 2900 The electron voltage of the ionizer provided by the embodiment of the invention is 150V, and the electron emission current is 20mA.
In order to allow the cluster beam incident on the Si target surface to have a certain energy, the electric field U applied to the cluster ion beam according to the embodiment of the present invention is set to 3 to 20kV, and the energy e= qU is distributed to 10.4 to 69keV. The embodiment of the invention monitors the incidence dose of the cluster beam to be 5.8x10 through a beam integrator 15 clusters/cm 2 。
In order to achieve the aim of improving the sputtering yield of Si atoms, the embodiment of the invention directly uses purchased nano Si powder (light yellow scientific grade single crystal silicon powder, purity is 99.9 percent, average grain diameter is 30nm, shanghai Koch New Material science and technology effective company) as a die casting Si target raw material. Repeatedly grinding the powder by an agate mortar to obtain superfine nano silicon powder with the average particle diameter of 12-15 nm, and die-casting the superfine nano silicon powder into a cylindrical block target by a hydraulic tablet press.
2. Application example. In order to prove the inventive and technical value of the technical solution of the present invention, this section is an application example on specific products or related technologies of the claim technical solution.
The sputter atomic yield when the heavy ions of energy keV irradiate the solid material is in accordance with the "hot pinning" effect, and not the higher the energy, the higher the sputter atomic yield, but there is a highest peak (thermapeak) of sputter atomic yield. This is also demonstrated in the example in figure 5.
In addition, for a cluster ion source, the energy of the cluster ion beam is derived from the acceleration voltage. When the accelerating field voltage can only be varied within a certain range, the energy has little effect on the sputter atomic yield, and the microstructure of the solid sputter target containing the atoms can be started to improve the sputter yield. The invention further grinds commercial nano scientific grade pure Si powder into powder with smaller size and then die casts the powder into a target, and the invention finds that the sputtering yield can be improved. Further, the fragments formed by the cluster ion beam bombardment are also beneficial to improving the sputtering yield.
When the invention is used for bombarding a solid target formed by die casting of nano silver (Ag) powder, aluminum (Al) powder and boron (B) powder by using Ar cluster ion beams, the yield of sputtered Ag, al and B atoms is found to be obviously improved. Therefore, the technology has universality in that the sputtering atom yield of the nano-structure solid-state target can be improved by experiments.
3. Evidence of the effect of the examples. The embodiment of the invention has a great advantage in the research and development or use process, and has the following description in combination with data, charts and the like of the test process.
Example 1
Fig. 2 provided by the embodiment of the invention is a schematic diagram depicting experimental gas cluster sputtering nano Si targets. Similar to a single ion sputtering target, (1) can be regarded as a single ion with large mass and large volume, and when the single ion interacts with (2), the energy deposition effect is used for generating (3), and finally atoms generated by sputtering are collected by (4) for observing the formed deposition layer and surface morphology structure and estimating the sputtering yield.
To verify the sputter yield of gas clusters at the same energy for Si targets of different microstructure morphologies, fig. 3 shows the sputter yield as a function of cluster energy for die cast Si nanopowder targets and single crystal silicon (100) targets. The nanopowder die cast Si target started to exhibit monotonically increasing sputter yield at an input beam energy of 34.5keV compared to the bulk Si target. In the work of the present invention, to explain this behavior, the present invention proposes a competitive model, the effective size effect promoting the sputtering of the nanosystems, while fragments formed by sputtering impair the limited size effect. The effective size effect can be confirmed by that energy of one cluster after collision with a certain amount of Si nanoparticles cannot be effectively transmitted inside the material due to the close arrangement between Si nanoparticles, which causes an increase in energy density of the collision region, and eventually, an increase in sputtering yield. In contrast, the formation of fragments increases the link between adjacent atoms (or fragments), which promotes the spread of energy, which can lead to a drop in sputter yield. Thus, if at a higher energy segment, cluster sputtering produces more fragments. However, at a certain energy, a significant accumulation of the number of fragments may cause a disappearance of the effective size effect, which is particularly evident when the beam energy is 17.3keV. The occurrence of the maximum sputter yield value at 17.3keV illustrates a particular mechanism of sputtering in this energy interval. One of these is that the Si nanoparticles exhibit a similar process to atom bombardment during collisions with the Ar cluster beam, they are more or less completely decomposed. Another mechanism is desorption of all nanoparticles having a nanoscale or less after release of the cluster energy.
Example 2
In the process of bombarding the target material by the energy-carrying ion beam, the energy of clusters colliding with the central area is converted into heat energy of the material, and atoms are evaporated after the material is melted. To verify the generation of nanoparticles in sputtered material, the present invention detects surface topography information of a collector placed near the target by TEM techniques, as shown in fig. 4. Nanoparticles were observed in all TEM images. However, these nanoparticles are present as islands on the grown silicon film. If the TEM magnification is increased, they have different shapes and different thicknesses (different contrast). Thus, the shape becomes more regular, similar to more fragments generated by the original Si nanoparticle, rather than island growth. Furthermore, at an energy of 69keV section, the sputtering yield is highest, and the number of some islands increases. However, the maximum number of islands occurs at 17.3keV, whereas the minimum occurs at 69keV. Thus, it can be said that during the cluster bombardment process, the nanoparticles on the collector are fragments of the original Si nanoparticles. The size distribution of these particles is given in fig. 5, with an average size of 62nm. The size distribution of all sputtered nanoparticles is asymmetric, accompanied by the prevalence of large-size particle distributions. No initial nanoparticle was found on the collector, indicating its extremely low emissivity under cluster collisions. In fig. 4, the average size of the sputtered nanoparticles after bombardment with 10.4keV cluster energy was observed to be 12nm. The number of sputtered particles reaches a maximum at 17.3keV as the energy of the cluster increases and then decreases again as the energy increases, but the average size of the particles remains in a scale range of 12 to 13 nm. The average size of the nanoparticles produced by the cluster beam bombardment sputtering at 10.4 and 17.3keV energies was higher than the pit size produced by the bombardment at the same energy. Furthermore, since the cluster energy is independent, it is shown that the sputtered particles observed during pit formation are not generated. Therefore, the sputtering mechanism should be derived from the formation of nanoparticles. If in the range of 10.4 to 34.5keV, the energy dependence of the sputter yield (see fig. 3) and the number of sputtered particles (see fig. 5) is compared, that is, in this energy interval, sputtering is caused by emission of nano-sized particles. The conclusion is that the nanoparticle formation mechanism is related to the size effect, which increases the sputter yield, and that the optimal cluster energy for nanoparticle formation is 17.3keV.
In summary, embodiments of the present invention provide a method for enhancing the atomic yield of a gas-cluster ion sputter target, involving two enhancement mechanisms. One is that at lower cluster energies, the effective size effect of the nanoparticles in the target results in a significant increase in sputtered atom yield; alternatively, at higher cluster energies, the fragments formed during the bombardment of the target by the cluster ions may contribute to an increase in sputter yield.
FIG. 2 is a schematic diagram of a gas cluster sputtering nano Si target provided by an embodiment of the present invention; the nano-sized Si powder die-casting target is taken as a test target material, ar cluster ion beams are used for bombardment, and sputtered Si atoms are collected by a collector.
FIG. 3 is a schematic diagram of sputter yields of a nano Si powder die-cast target and a bulk Si target provided by an embodiment of the present invention under different cluster ion beam energies; this figure gives direct evidence that Si targets with nanostructures are higher in yield than bulk Si targets sputtered at the same cluster ion beam energy, demonstrating why the need to provide nanosized solid state targets in the claims.
FIG. 4 is a TEM image of a sputter-generated deposit on a collector surface at different cluster energies provided by an embodiment of the present invention; this figure shows the cluster ion beam energy for different Si sputter yield correspondences to verify that sputter formed cluster fragments are the reason for the high sputter yield.
FIG. 5 is a schematic diagram of the relationship between the nano Si particle size and the number of Si atoms produced by sputtering in a target provided by an embodiment of the present invention; it was further confirmed that the Si target having the nanostructure can improve the sputtering rate thereof.
It should be noted that the embodiments of the present invention can be realized in hardware, software, or a combination of software and hardware. The hardware portion may be implemented using dedicated logic; the software portions may be stored in a memory and executed by a suitable instruction execution system, such as a microprocessor or special purpose design hardware. Those of ordinary skill in the art will appreciate that the apparatus and methods described above may be implemented using computer executable instructions and/or embodied in processor control code, such as provided on a carrier medium such as a magnetic disk, CD or DVD-ROM, a programmable memory such as read only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The device of the present invention and its modules may be implemented by hardware circuitry, such as very large scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., as well as software executed by various types of processors, or by a combination of the above hardware circuitry and software, such as firmware.
The foregoing is merely illustrative of specific embodiments of the present invention, and the scope of the invention is not limited thereto, but any modifications, equivalents, improvements and alternatives falling within the spirit and principles of the present invention will be apparent to those skilled in the art within the scope of the present invention.
Claims (10)
1. A method of enhancing the atomic yield of a gas cluster ion beam sputtered solid target, the method comprising: ar gas cluster ion beams with determined sizes and nano Si powder die-casting targets, wherein the Ar gas cluster ion beams bombard the nano Si powder die-casting targets, and part of Si nano particles generated by sputtering are captured by a collector.
2. The method of claim 1, wherein the method of fabricating nano-Si powder die-cast targets comprises grinding and hydroforming.
3. The method of enhancing the atomic yield of a gas-cluster ion beam sputtered solid target as claimed in claim 2 wherein the grinding in the method of fabricating nano-Si powder die-cast targets comprises: grinding the purchased scientific grade nano Si powder with the average particle size of 30nm into superfine powder with the average particle size of 12-15 nm.
4. The method of enhancing the atomic yield of a gas-cluster ion beam sputtered solid target as claimed in claim 2 wherein the hydroforming in the fabrication of nano-Si powder die-cast targets comprises: the milled Si powder was processed by a hydraulic tablet press under a pressure of 6MPa for 15min.
5. The method of enhancing the atomic yield of a gas cluster ion beam sputtered solid state target of claim 1, wherein the method of enhancing the atomic yield of a gas cluster ion beam sputtered solid state target comprises the steps of:
firstly, generating neutral Ar gas cluster beams, opening a main argon valve of a steel cylinder, adjusting a pressure reducing valve to 0.2-0.5 MPa, introducing Ar gas into an ion source cavity of the gas cluster through a pressure-resistant gas conduit, entering a differential vacuum chamber of 0.01-0.1 Pa through a Laval ultrasonic nozzle, and performing ultrasonic adiabatic expansion on the gas to form the neutral cluster beams containing thousands to tens of thousands of Ar atoms;
step two, the accelerated cathode filament electrons collide and ionize, so that Ar cluster beams become cluster ion beams; the neutral Ar cluster beam advances along the central axis of the pipeline through the adjustment of the four-dimensional collimator, and after the electrons emitted by the cathode filament collide, a small part of clusters are ionized into Ar cluster ion beams;
step three, the cluster ion beam becomes an energy-carrying cluster ion beam after passing through an accelerating electric field; and in the second step, direct-current high voltage is applied to the pipeline space behind the cathode filament, so that higher incident energy is given to the Ar cluster ion beam.
6. Such asThe method of claim 5, wherein in step one, for screening the number of Ar atoms in Ar clusters, the electric field accelerated cluster ion beam is passed through a speed selector to determine the speed v of the cluster beam, and the speed v is determined according to qU =1/2 mv 2 Obtaining the mass m of a single cluster beam, wherein q is the effective charge number of the cluster ion beam and can be directly given by a beam integrator; and (3) providing an effective experimental parameter characteristic value, wherein the Ar cluster beam contains N=2900 Ar atoms, the effective charge number q after ionization is 3.45, and the Ar cluster ion beam characteristic parameter relation of N/q=840 is satisfied.
7. The method of claim 5, wherein in step two, the cathode filament electron voltage is 150V and the electron emission current is 20mA.
8. The method of enhancing the atomic yield of a gas-cluster ion beam sputtered solid target according to claim 5 wherein in step three, the electric field U applied to the cluster ion beam is set to 3 to 20kV and the energy distribution is 10.4 to 69keV; monitoring the incidence dose of the cluster beam by a beam integrator to be 5.8X10 15 clusters/cm 2 。
9. A computer device comprising a memory and a processor, the memory storing a computer program which, when executed by the processor, causes the processor to perform the steps of the method of enhancing the atomic yield of a gas cluster ion beam sputtered solid target according to any one of claims 1 to 8.
10. A computer readable storage medium storing a computer program which, when executed by a processor, causes the processor to perform the steps of a method of enhancing the atomic yield of a gas cluster ion beam sputtered solid target as claimed in any one of claims 1 to 8.
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