CN101549853A - Processing method for constructing nano projection structure on surface of single crystal silicon based on friction induction - Google Patents

Abstract

A processing method for constructing nano projection structure on surface of single crystal silicon based on friction induction adopts diamond tip in the shape of spherical crown as processing tool on the scanning probe microscopy to scan the surface of single crystal silicon material. The load exerted on diamond tip is 0.02-1 times of critical theory load on the broken surface of single crystal silicon, namely, the surface of single crystal silicon can be processed into projection structure in linear, planar and other complex shapes. Electric field, and any chemical treatment on the material surface are not needed in the process, and the process is pollution-free. The nano projection structure can be processed on the material surface when exerting a certain load on the surface through the tip. The method has simple process and good processing repeatability. Mechanical stability of the projection structure is good. The tip with big curvature radius is used, load is less, and service time of the tip is long.

Description

A kind of processing method based on friction induction structure monocrystalline silicon surface nano projection structure

Technical field

The invention belongs to technical field of nano-processing, can be used for the processing of material surface nanoscale bulge-structure.

Background technology

Micro-nano process technology is the important component part of Modern high-tech industry.The development of micro-nano process technology has promoted development of integrated circuits, leads the integrated level of integrated circuit to improve with per speed of doubling in 18 months.In recent decades, the research of nano electron device has obtained the progress of advancing by leaps and bounds.But, change these achievements in research into circuit and device and still depend on advanced nanoprocessing manufacturing technology with calculation function.Because the typical sizes of nano electron device is in nanometer scale, traditional Machining Technology such as cutting have been unsuitable for the processing of its parts.In addition, along with development of integrated circuits, the manufacturing with new-type circuit chip of very fine structure brings great challenge also for traditional nanofabrication technique.When improving original processing technology, the nanofabrication technique of seeking a new generation is extremely urgent.

Nano electron device mostly is made of various nano dots, nano wire and nanometer convex region etc.Therefore, the key of its manufacturing is how to realize the controlled processing of these nano projection structures.According to the difference of principle, present nanoprocessing method mainly contains:

Photoetching technique: utilizing optics one chemical principle and chemistry, physical etchings method, by template circuitous pattern is delivered on single-crystal surface or the dielectric layer, is at present unique process technology that the micro-/ nano devices in batches is produced that is used for.Along with improving constantly of machining accuracy, this method cost is also more and more higher, its technical limitation is also further highlighting, as: be difficult to eliminate mask version base version defective, be difficult to improve easily problem such as pollution of the surface smoothness of silicon chip and mask plate and the depth of parallelism between the two, light source photoresist costliness, optical system.In a word, along with the development of nanofabrication technique, photoetching technique develops into its " application limit " gradually.

Monatomic manipulation based on PSTM: between the probe of PSTM and test specimen surface, apply bias voltage, move and arrange the atom that is adsorbed on the matrix surface, can process required nanostructured by needle point.This method is subjected to accuracy and can successionally limits, and working (machining) efficiency is low, still is difficult to drop into actual production.

Anodizing based on scanning probe microscopy: the processing method that forms the nano-oxide structure by tunnel current effect between scan-probe and the sample and electrochemical reaction.In process, probe is the negative electrode of electrochemical reaction, and sample is an anode, can make several atomic layers of test specimen surface oxidation occur.The machining accuracy of this method is subjected to the factor affecting such as size, ambient humidity and sweep speed of bias voltage between sharpness, probe and the test specimen of probe.Because anodizing requires sample to conduct electricity, and can be used for processing metal and semiconductor samples usually, and is then powerless to insulated samples such as nonmetal and organic matters.

Scanning probe microscopy can be realized the machining accuracy of atom magnitude, and method such as the parallel processing of multiprobe can improve working (machining) efficiency effectively, and probe technique has broad application prospects in the manufacturing of nano electron device.Yet existing scanning probe microscopy nanoprocessing method need apply electric field usually, and controlled condition is more, complicated operating process.Therefore, need the new method of researching and proposing the simple scan-probe processing of a kind of technology nano projection structure badly.

Summary of the invention

The purpose of this invention is to provide the simple monocrystalline silicon surface nano projection structure of a kind of operating process method for processing.This method is simple to operate, the precision height, and good reproducibility, the reliability height can be nanoprocessing new way is provided.

The present invention realizes its goal of the invention, the technical scheme that is adopted is: with point is that the diamond probe of spherical crown shape is installed on the scanning probe microscopy, monocrystalline silicon piece is fixed on the sample bench of scanning probe microscopy, start scanning probe microscopy, apply the load F of setting and make its needle point delineate and to process nano projection structure at monocrystalline silicon surface at monocrystalline silicon sheet surface along the track of setting to scan-probe; Wherein, the value of the load F that applies to scan-probe, determine by the following method:

(1) by formula $\frac{1}{E}=\frac{1-{\mathrm{<figure-callout\; id="1"\; label="v"\; filenames="A20091005927200101.png,A20091005927200112.png"\; state="\{\{state\}\}">v</figure-callout>}}_1^2}{{\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="A20091005927200101.png,A20091005927200112.png"\; state="\{\{state\}\}">E</figure-callout>}}_1}+\frac{1-{\mathrm{<figure-callout\; id="2"\; label="v"\; filenames="A20091005927200121.png,A20091005927200122.png"\; state="\{\{state\}\}">v</figure-callout>}}_2^2}{{\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="A20091005927200121.png,A20091005927200122.png"\; state="\{\{state\}\}">E</figure-callout>}}_2}$ Calculate equivalent elastic modulus E, v in the formula ₁, v ₂Be respectively the Poisson's ratio of needle point and monocrystalline silicon, E ₁, E ₂Be respectively the elastic modelling quantity of needle point and monocrystalline silicon;

(2) by formula $F_{}$ ${}_0=\frac{{{\mathrm{\&sigma;}}_c}^3{\mathrm{\&pi;}}^3{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A20091005927200121.png,A20091005927200122.png"\; state="\{\{state\}\}">R</figure-callout>}}^2}{{6\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="A20091005927200121.png,A20091005927200122.png"\; state="\{\{state\}\}">E</figure-callout>}}^2}$ Calculate monocrystalline silicon sheet surface the pairing theoretical critical fire area load of the limit stress F of destruction takes place ₀, σ in the formula _cBe the hardness of monocrystalline silicon, R is the radius of curvature of diamond needle point.

(3) the load F that applies of scan-probe is theoretical critical fire area load F ₀0.02-1 doubly.

Compared with prior art, the invention has the beneficial effects as follows:

One, the present invention does not need extra electric field, does not need special chemical treatment is done on the surface, directly adopts the method for machining can form the required specific bulge-structure of nano electron device, and its operating process is simple, the working (machining) efficiency height.

Two, scan-probe is carried out line sweep (delineation) by the wire track of setting, can obtain the nanoscale bulge-structure of wire; Utilize scan-probe on selected zone, to carry out face scanning (delineation), can be made into planar bulge-structure.The height of bulge-structure is by load that applies and the decision of delineation number of times, and width is by the size decision of probe pinpoint end.Its machining reproducibility is good, and the precision height can be made different in width and bulge-structure highly according to actual needs.

Three, the bulge-structure that forms of the inventive method mainly is that surface by single crystal silicon material is subjected to being formed by the effect less than the power of surface breakdown critical load that probe applies; Be not that foreign substance adheres to formation, chemical reaction does not account for leading role yet.Bulge-structure and substrate are combined, good mechanical stability.

Four, the diamond needle point tip that is used to process is the spherical crown shape, and its wear rate is low, long service life.

Five, for online observation or evaluation processing effect, so that realize high-precision customization processing, can after first sample processing, need not take off sample, (used load＜10nN in the scanning process is theoretical critical fire area load F directly to utilize the probe that is exclusively used in the scanning pattern that machining area is carried out former bit scan ₀Below 1/1000, can produce not destroy or other influences the surface), promptly can be observed the three-dimensional appearance of the bulge-structure that processes at sample surfaces.Height of projection as sample is not enough, can utilize the diamond probe to carry out the processing second time, until being processed into certified products.After the test by a few sample, can accurately set machined parameters easily, carry out large batch of high accuracy processing.Less wastage in the process, the qualification rate height.

The present invention is described in further detail below in conjunction with the drawings and specific embodiments.

Description of drawings

Fig. 1 processes the wire bulge-structure that obtains for the method for the embodiment of the invention one to the single crystal silicon material surface.The concrete parameter of materials processing is among the figure: the high preferred orientation of monocrystalline silicon piece is (100), thickness 0.5mm, scanning probe microscopy (SPM) adopts the SPI3800N type, scan-probe is the diamond needle point, the coefficient of elasticity of its cantilever beam is 180N/m, and the radius of curvature of diamond needle point spherical crown shape point is about 430nm.

Wherein the processing load of a1-a4 component correspondence is 135 μ N, the scan cycle number of times is respectively 1 time, 20 times, 100 times, 500 times;

The scan cycle number of times of b1-b4 component correspondence is 200 times, corresponding processing load and is respectively 45,55,85,135 μ N.

Fig. 2 be utilize bulge-structure that the present invention makes in pure water after ultrasonic wave cleans 20 minutes no change.(a) and (b) be respectively the pattern before and after cleaning.

Fig. 3 is the planar bulge-structure of the embodiment of the invention one in Si (100) Surface Machining.Used load is 85 μ N, and scanning times is 11 times, and this planar projection is of a size of 5 μ m * 5 μ m.

Fig. 4 is the nano dot structure of the embodiment of the invention in Si (100) Surface Machining.Used load is 10 μ N, and delineation length is 20nm, and the delineation number of times is 100 times.

" TRI " of Fig. 5 for inscribing out on Si (100) surface through the embodiment of the invention one method.Used load is 50 μ N during inscription, and the cut cycle-index is 50 times.

Fig. 6 is " TRI " printed words that the needle point that utilizes radius of curvature R to be about 100nm goes out in monocrystalline silicon (100) Surface Machining: used load is 150nN, and the delineation cycle-index is 100 processing results on monocrystalline silicon (100) surface.

Fig. 7 is the wire bulge-structure that utilizes radius of curvature R to process at monocrystalline silicon (100) for the needle point of 5000nm: used load is 1mN, and the delineation number of times is 1 time.

The specific embodiment

Embodiment

A kind of specific embodiment of the present invention is: a kind of processing method based on friction induction structure monocrystalline silicon surface nano projection structure, and its concrete practice is:

With point is that the diamond probe of spherical crown shape is installed on the scanning probe microscopy, monocrystalline silicon piece is fixed on the sample bench of scanning probe microscopy, start scanning probe microscopy, apply the load F of setting and make its needle point delineate and to process nano projection structure at monocrystalline silicon surface at monocrystalline silicon sheet surface along the track of setting to scan-probe; Wherein, the value of the load F that applies to scan-probe, determine by the following method:

(1) by formula $\frac{1}{E}=\frac{1-{\mathrm{<figure-callout\; id="1"\; label="v"\; filenames="A20091005927200101.png,A20091005927200112.png"\; state="\{\{state\}\}">v</figure-callout>}}_1^2}{{\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="A20091005927200101.png,A20091005927200112.png"\; state="\{\{state\}\}">E</figure-callout>}}_1}+\frac{1-{\mathrm{<figure-callout\; id="2"\; label="v"\; filenames="A20091005927200121.png,A20091005927200122.png"\; state="\{\{state\}\}">v</figure-callout>}}_2^2}{{\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="A20091005927200121.png,A20091005927200122.png"\; state="\{\{state\}\}">E</figure-callout>}}_2}$ Calculate equivalent elastic modulus E, v in the formula ₁, v ₂Be respectively the Poisson's ratio of needle point and monocrystalline silicon piece, E ₁, E ₂Be respectively the elastic modelling quantity of needle point and monocrystalline silicon piece;

(2) by formula $F_{}$ ${}_0=\frac{{{\mathrm{\&sigma;}}_c}^3{\mathrm{\&pi;}}^3{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A20091005927200121.png,A20091005927200122.png"\; state="\{\{state\}\}">R</figure-callout>}}^2}{{6\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="A20091005927200121.png,A20091005927200122.png"\; state="\{\{state\}\}">E</figure-callout>}}^2}$ Calculate monocrystalline silicon sheet surface the pairing theoretical critical fire area load of the limit stress F of destruction takes place ₀, σ in the formula _cBe the hardness of monocrystalline silicon, R is the radius of curvature of diamond needle point.

(3) the load F that applies of scan-probe is theoretical critical fire area load F ₀0.02-1 doubly.

The radius of curvature of the spherical crown shape point of the scan-probe that this is routine is 100nm-5 μ m (5000nm).

Monocrystalline silicon piece in this example can clean earlier before processing, and the specific practice of cleaning is ultrasonic cleaning in chloroform, acetone, pure water successively.Can avoid of the harmful effect of the pollutant of material surface like this to process and formation structure.

Below be several concrete processing experiment process and the result who adopts the example method to carry out:

The radius of curvature of test 1～4 diamond needle point of selecting for use is 430nm, because the hardness of monocrystalline silicon piece is 13GPa, and the Poisson's ratio v of diamond and monocrystalline silicon piece ₁, v ₂Be respectively 0.28 and 0.07, the elastic modulus E of diamond needle point and monocrystalline silicon piece ₁, E ₂Be respectively 130 and 1141GPa.Formula according to (1), (2) obtains in test 1～4 the critical load F that the diamond needle point is applied ₀Should be 135 μ N, so the load that applies on the diamond needle point should not be higher than 135 μ N.

1, the processing experiment of wire projection:

Add actual conditions and the parameter selected for use man-hour: sample is the monocrystalline silicon piece of the about 0.5mm of thickness, its high preferred orientation is (100), adopt SPI3800N type scanning probe microscopy as process equipment, the scan-probe that is adopted is the diamond needle point, the coefficient of elasticity of its cantilever beam is 180N/m, and the radius of curvature of diamond needle point spherical crown shape point is about 430nm.Load is chosen for 45,55,85,135 μ N respectively in the test, and the cycle-index during delineation is chosen for respectively 1,20,50,100,200,500 time, and the track of setting during delineation is a straight line.

Adopt above parameter condition that a plurality of silicon single crystal wafers are carried out processing experiment, the result shows, all can form good bulge-structure at monocrystalline silicon surface.

To the monocrystalline silicon piece after the above processing, the tip shape silicon nitride needle point that can utilize the small curvature radius (about 30nm) that is exclusively used in the scanning pattern carries out former bit scan to machining area, the wire bulge-structure that obtains processing under low load (less than 10nN) condition.Accompanying drawing 1 has provided part shape appearance figure wherein.Wherein the processing load of a1-a4 component correspondence is 135 μ N, the scan cycle number of times is respectively 1 time, 20 times, 100 times, 500 times; The scan cycle number of times of b1-b4 component correspondence is 200 times, corresponding processing load and is respectively 45,55,85,135 μ N.As can be seen, the width of wire bulge-structure can be controlled in tens nanometers to the hundreds of nanometer from each shape appearance figure, and height can reach 10nm; The width of bulge-structure and height and cycle-index and the imposed load relation of being proportionate.

Fig. 2 has then provided the exterior appearance figure of 20 minutes forward and backward bulge-structures of ultrasonic wave cleaning in the pure water, and Fig. 2 shows the bulge-structure good mechanical stability that the present invention makes, and is cleaning forward and backward no any variation.

2, the processing experiment of planar projection:

Adding the concrete parameter load of selecting for use man-hour is 50 μ N; Employing face scan mode (being the track next-door neighbour of adjacent two line sweeps), scanning area is 5 μ m * 5 μ m, and scanning step (spacings of adjacent two scan lines) is 19.5nm, and scan frequency is made as 2Hz (being to finish line sweep each second twice).Scanning times is 11 times, and all the other processing conditions are identical with the processing of above wire projection with parameter.

Adopt the silicon nitride needle point that machining area is carried out former bit scan, obtain the planar bulge-structure as Fig. 3, it highly is 4nm.

The processing experiment of planar projection shows that also along with the increase of load and scanning times, the height of planar protuberance also can correspondingly increase.The area minimum controllable is built in tens square nanometers.

3, the processing experiment of nanometer salient point:

Add the concrete parameter of selecting for use man-hour, load is 10 μ N, and the diamond needle tongue mark of setting is fixed point, delineation (circulation) 100 times, and delineation length is 20nm.All the other parameters, condition are then identical with the processing of above wire projection.

After delineation is finished, adopts the scanning of highly sensitive silicon nitride needle point original position to characterize and delineates effect, the result as shown in Figure 4, the height of this nano dot is about 1.4nm, diameter is about 100nm.

4, the processing experiment of complicated shape bulge-structure:

Add the concrete parameter of selecting for use man-hour: load is 50 μ N, and cycle-index 50 times, scan frequency are 2Hz.All the other parameters, condition are then identical with the processing of above wire projection.The track while scan of setting is that the pen that pursues in " TRI " three words pursues picture.Each stroke is all set its corresponding angle and length, is set at the scan line track of 0 °, 2 μ m and 90 °, 3.5 μ m respectively as the horizontal stroke "-" of " T " and perpendicular " Shu "; Remaining machined parameters condition is also identical with the processing of wire bulge-structure.

Select the high silicon nitride needle point of scan sensitivity for use, scan inscribing the zone, the portrayal effect that obtains is seen accompanying drawing 5.As seen from Figure 5, adopt method of the present invention to inscribe out the bulge-structure of the complicated shape that is shaped as " TRI " by setting requirement.

Obviously, the present invention can set different delineation tracks as required, processes the bulge-structure of different various complicated shapes.

5, radius of curvature is the processing experiment of the diamond needle point of 100nm

Adding the concrete parameter of selecting for use man-hour is: the radius of curvature of diamond needle point point is about 100nm, calculates the theoretical critical fire area load F that monocrystalline silicon sheet surface takes place by destruction through formula (1), (2) ₀Be 7500nN; Used load is 150nN (for 0.02 times of theoretical critical fire area load) in this test, the delineation cycle-index is 100 times, remaining processing conditions, parameter and technology are all identical with the processing of the complicated shape bulge-structure of above test 4, pattern such as Fig. 6 of being shaped as " TRI " bulge-structure that scanning obtains.

6, radius of curvature is the processing experiment of the diamond needle point of 5 μ m

Adding the concrete parameter of selecting for use man-hour is: the radius of curvature of diamond needle point point is 5 μ m, calculates the theoretical critical fire area load F that monocrystalline silicon sheet surface takes place by destruction through formula (1), (2) ₀Be 18mN, used load is 1mN (for 0.06 times of theoretical critical fire area load) in this test, the delineation cycle-index is 1 time, and remaining processing conditions, parameter and technology are all identical with the processing of the wire bulge-structure of above test 1, scan pattern such as Fig. 7 of obtaining.

Evidence, thickness and the cycle-index positive correlation of the bulge-structure of the present invention processing, as long as but the load that applies in 0.02-1 times scope of theoretical critical load, just can process bulge-structure at monocrystalline silicon surface.The load that applies can be processed into tangible bulge-structure 1 time in 0.02 times of theoretical critical load, circulation 100 times or the load that applies at 0.2 times of theoretical critical load, circulation.If need the thicker bulge-structure of processing, then can realize by applying bigger load and/or increasing cycle-index.

Claims (2)

1, a kind of processing method based on friction induction structure monocrystalline silicon surface nano projection structure, its concrete practice is: with point is that the diamond probe of spherical crown shape is installed on the scanning probe microscopy, monocrystalline silicon piece is fixed on the sample bench of scanning probe microscopy, start scanning probe microscopy, apply the load F of setting and make its needle point delineate and to produce nano projection structure at monocrystalline silicon surface at monocrystalline silicon surface along the track of setting to scan-probe; Wherein, the value of the load F that applies to probe, determine by the following method:

(1) by formula $\frac{1}{E}=\frac{1-v_1^2}{E_1}+\frac{1-v_2^2}{E_2}$ Calculate equivalent elastic modulus E, v in the formula ₁, v ₂Be respectively the Poisson's ratio of diamond and monocrystalline silicon, E ₁, E ₂Be respectively the elastic modelling quantity of diamond and monocrystalline silicon;

(2) by formula $F_0=\frac{{{\mathrm{\&sigma;}}_c}^3{\mathrm{\&pi;}}^3{R}^2}{6E^2}$ Calculate monocrystalline silicon sheet surface the pairing theoretical critical fire area load of the limit stress F of destruction takes place ₀, σ in the formula _cBe the hardness of monocrystalline silicon, R is the radius of curvature of diamond needle point;

(3) the load F that applies of scan-probe is theoretical critical fire area load F ₀0.02-1 doubly.

2, a kind of processing method based on friction induction structure monocrystalline silicon nano projection structure according to claim 1, it is characterized in that: the radius of curvature of the spherical crown shape point of described scan-probe is 100nm-5 μ m.

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