The small machining technology of CVD diamond film considers to make progress

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Summary: Diamond film is a kind of contain the material of new-style electron function of tremendous application latent capacity, but its extremely tall hardness and chemical stability make its are machined to shape hard, accordingly, one of crucial technology issues that the small machining technology of diamond film is its MEMS application. The article introduced growing domestic and internationally optionally in recent years, duplicate, laser engraves the model corrode and plasma engrave the diamond personal computer such as corrode to fetters the research of processing technique respect makes progress, emphasize discussed the reaction ion that can have imperceptible treatment to diamond film directly to engrave corrode technology, the idea of passivation of sidewall of film of metallic attack by surprise that put forward to improve small machining result, the diamond small structure that is MEMS parts of an apparatus is compositive production open up more accurate and efficient technology way. System of Electromechanical of 1 foreword miniature (MEMS) technology promotes 20 centuries of result 80 time, great progress was obtained in ten years of in the past, had made one of important and new and high technologies that have wide application perspective now, coming true gradually from consider to give priority to the move to industrial application development with the lab. The development that accompanying new technology, new material and application, all sorts of new-style MEMS parts of an apparatus emerge in endlessly. Stem from the long-term consideration of pair of final industrialization, people rises increasingly to the requirement of life of parts of an apparatus and dependability, the material that makes investigator examine small rigid structure afresh selects an issue. Up to now, the electronic data that place of MEMS parts of an apparatus uses can divide it is two kinds: Silicon (base) with the material that be not silicon. Because acceded,the long-term technology of semiconductor industry is accumulated, the body silicon that creates demand in the light of system of personal computer cable and instrument of exterior silicon personal computer processing technique early formed system of relatively whole small processing technique, accordingly, predominate of parts of an apparatus of silicon radical MEMS, caused silicon thereby (base) material holds overwhelming advantage position in MEMS data system. Film of the monocrystalline silicon that regards small structure as material especially, polycrystalline silicon and nitrogen change silicon to wait for film of silicon radical compound, they have more long-term development to use the history in semiconductor industry, corresponding processing technique also has rich accumulate. Although suit the processing technique of small rigid structure to have its oneself characteristic, but still have can be used for the most part very much or draw lessons from, so, most MEMS parts of an apparatus is based on silicon data design. In addition, the material of material of silicon radical MEMS and circuit part is compatible, facilitating implementation whole is compositive make, this is farther aggrandizement its advantage position. But, MEMS parts of an apparatus has after all to the requirement of material fasten the semiconductor device at the tradition, the defect of silicon material expands as what use range and show increasingly, for instance of silicon fight a turn to lose strength low and rupture tenacity is poor, fight wear away capability is not strong, return phenomenon of conglutinate of particularly incidental structure, so, component of the motion in current MEMS parts of an apparatus basically chooses deformation of move back and forth, means moves commonly in taking the macroscopical machine such as slippage of rotational, contact rarely. Accordingly, the other data origin besides development silicon will promote the development of MEMS technology. Besides, be based on the electromagnetism, small drive construction that controls the principle implementation such as memory effect of report, appearance to also must use construction of the material that be not silicon, cannot realize the integral function of MEMS parts of an apparatus otherwise. In fact, as the material that be not silicon the ceaseless progress of three-dimensional small processing technique, titanium of nickel of nickel, copper, iron, nickel, gold, alumina even diamond film be taken seriously increasingly, already more and more material that be not silicon are applied at tectonic MEMS parts of an apparatus, work in promotion parts of an apparatus and system the action with ability respect individual play, among them diamond film is one of data of function of small rigid structure that provide potential most. The place of advantageous physico-chemical characteristic already extensive humanness of CVD diamond film knows, build in its many sided on admirable and characteristic foundation, the applied domain that has come true includes cutting tool exceed hard coating, loudhailer brace up velar coating, laser and integrated circuit carbon fin, material of X ray window, edition of film of X ray attack by surprise struts stuff, optical component coating. Be approbated extensively to have the applied domain that apply foreground potentially and extending actively to include material of semiconductor device of high temperature high power, cold cathode blasts off and show stuff of parts of an apparatus, material of powerful laser window, the composite material of diamond besmear Fu, high frequency paragraph parts of an apparatus of surface acoustic wave, disk coating material and MEMS construction material and functional coating. Regard small structure as material, CVD diamond film has a lot of incomparable advantageous character. Diamond film quality is light, intensity is high, wear-resisting caustic, fight corrode, thermal conductivity, insulating properties is good. Compare with silicon photograph, the mechanical intensity of diamond film and hardness tower above are close decuple, the turn folds intensity tower above 20 times above, tower above of wear-resisting caustic ability 1000 times above, the advantage of integral performance is very clear, behoove regards the first selection of the structural member in system of personal computer cable as material. If can use as small gear, cantilever bridge, small hinge, small bedspring, small connecting rod, slide block material. At the same time diamond film has tall resistor rate, tall puncture field is strong, low dielectric constant, coefficient of extremely small linear expansion, broad spectrum passes through limits, width of broad forbidden band, extremely tall carry stream child function of the exceedingly good light such as mobility, machine, report, can use as extensively the main body component of system of cable of specific function personal computer, be like small sensor, small brake, crepuscular parts of an apparatus, and, of diamond film high temperature resistant gender, be able to bear or endure corrode sex makes diamond MEMS parts of an apparatus can leave regular job in harsh environment, place of other electron stuff cannot replace this. But, shangbuduo sees the parts of an apparatus of diamond film MEMS that has developed a success, only minority sensor of a few special type, besides, only a few simple small structures wait like cantilever bridge, investigate its reason, diamond film is machined hard is one of main reasons. Be the hardness with diamond extremely tall film and chemical stability, make the imperceptible treatment of diamond film makes very difficult task. Accordingly, grow into one of main measures that for diamond small structure shapes optionally, besides, laser engraves corrode, model duplicate, ionic bundle of quarter corrode and reaction ion engrave corrode method to also have certain exploration, the comparison that afore-mentioned basic technology characteristics of all sorts of small treatment methods make a system with newest progress sums up article put up with, the sidewall passivation technology that uses oxygen to react the ionic technology that engrave corrode undertakes diamond film small machining spreads out to be discussed in detail. 2 grow optionally the technology grows optionally because the technology does not need costly plasma to cut corrode facility, become at present diamond film graph changes the commonnest method. Use silicon surface to be able to raise the principle of density of CVD reaction nucleate substantially after diamond pink burnish, surface of ministry of play a game of chess undertakes activation is handled, come true to grow optionally thereby. Its technological process is as follows roughly: Film of silicon of a 2 oxidation grows on preexistence polish silicon chip, the overburden of groovy gelatinize, photoetching, 2 oxidation silicon that corrodes surface of take out part optionally, use next contain diamond powder (diameter of bead of 10 ~ 50µm) suspension fluid undertakes ultrasonic is handled, make base piece the nucleate density of the part that the surface was not covered by SiO2 rises greatly (can amount to) of 10/µm2 amount class, the 2 oxidation silicon that working procedure of the line before corroding purify next withholds is filmy, form nucleate ability to have two kinds of area of tremendous contrast in silicon chip surface thereby, when using film of diamond of deposit of law of the CVD that heat up solution, because be enclothed by SiO2 when supersonic processing partial nucleate density is very low, it is the 10-4 ~ 10-3 that reveals a part only, can win the diamond film figure that grows optionally so. Have the aid of is similar method, ramesham grows optionally on silicon chip a diamond film graph, make the MEMS small structure that gets a few kinds of typical cases through sacrificial layer craft next, wait like film of small cantilever bridge, free diamond, graphical line is broad make an appointment with 8µm, grain load one's writing with fancy phrases is compact, show a triangle mostly (111) face, but border is not quite orderly, cannot see small structure has apparent side. Place of metallurgy of Shanghai of Chinese Academy of Sciences passes laboratory of feeling technology state to be used likewise grow optionally the technology made structure of rotor of diamond small motor. The gas phase of microwave plasma chemistry that increases with dc bias voltage above all is deposit (MPCVD) is right graphical area (Si) high density spends diamond nucleate, catch area of pair of film of attack by surprise (SiO2) has chemistry shallow corrode, grow normally next diamond is filmy, the diamond with get the face attrib border and smooth, clear is careful graph, when ply of diamond small structure is 2µm, graphical clearance is controallable to 1-2µm. A of this method marked characteristic is not to need to process hard and inert diamond film directly, evasive the main and difficult element of this domain, have its rationality and advantage so. But because cannot control the nucleate appearance of screen area thoroughly, film of this area diamond grows to undertake at the same time with nucleate drive area, just speed is gotten relatively slow much, if diamond film is strange long very long, criterion area also can be reduced optionally, cause the structural adhesion that does not hope to appear, the small structure ply that can grow optionally commonly so is thinner. The isotropy that exists as a result of CVD reaction at the same time grows trend, the precision of small structure size control is finite, elaborate structure is conveyed hard. 3 laser engrave laser of pulse of corrode have the aid of to undertake to diamond film the surface decorates treatment and small structure processing to be taken seriously extensively all the time, traditional laser beam machining is used infra-red, visible light and ultraviolet the common laser of wave band, treatment precision is inferior. Latter a variety of short pulse laser by extensive try out, include the accurate element laser of accept second pulse and flying second laser to wait to all have story of relevant research result. Laser beam machining uses focusing laser light beam surface of direct illuminate diamond, process is simple, the stress that studies the work is seeking proper craft condition centrally, the surface that makes the corrode that be engraved is machined can be achieved as far as possible smooth regulation, the harm of small to what stay after treatment structure as far as possible little. Park not only the basic law that considered to use focusing to allow an element to stimulate beam of light to cut film of corrode CVD diamond without film of attack by surprise, for instance amount of environmental gas discharge, luminous intensity, pulse the influence that wait, and designed platform of jiggle of pilot of a computer with operating beam of light has target small structure directly quarter write, obtained more satisfactory graph to turn treatment result. Research still observed laser carves the action range of the plasma that corrode diamond produces, the diamond surface loss that causes by place of this kind of plasma is considered as to create treatment area not quite smooth, regular main reason. Although the duration of laser pulse and diamond film action is OK,control is in accept second course is shorter perhaps, but, from this and the plasma of generation can last however tens of millisecond, plasma of this kind of high temperature can cause diamond of quarter corrode interface carbolic change becomes black lead condition or vitreous state, still can bring about twist of quarter corrode border and part to engrave corrode material to splatter again deposit, its incidence is quite big, it is the main technique obstacle that micron class machines. Use it is OK and certain to exceed short pulse laser afore-mentioned harms are reduced on degree. Shirk Michael use exceed laser of short pulse sapphirine to cut film of corrode CVD diamond, make quarter corrode border had very big improvement, side direction fire damage is not quite serious, basically also cannot see the again deposit quarter corrode thing after splattering. What make a person be interested more is to engrave the surface after corrode to detect almost the black lead carbon that is less than remaining, restrained quantity of heat to transfer a process according to thinking because exceed short pulse laser,this is. But, also the author thinks to shorten pulse not can from go up at all the generation that eliminates plasma, improve process capability to answer from restrain plasma proceed with. The Park environment when considering to change the reaction that engrave corrode to happen further cuts the method of corrode effect with the influence. Environment of low vacuum of have the aid of can reduce the again deposit phenomenon of quarter corrode material significantly, but quarter corrode border did not get ameliorative, the action limits of plasma expands somewhat instead. Differ with vacuumize and condition of big compression ring, aim the dot that engrave corrode to be blown continuously with argon air current, OK however and marked improvement cuts corrode result, not only quarter corrode border is regular and smooth, and plasma is very slight also to the injury of proximate surface, it is more advantageous treatment craft condition. Getting redeeming gradually besides each afore-mentioned inadequacy, laser engraves corrode to still have a few other drawback, how to accomplish the diamond film that cuts target position completely already not to injure underlay and the structure that keep again, it is a task that needs careful research, in addition, scanning engraves the efficiency of the treatment that write type to also remain to rise. Itself of duplicate diamond film machines 4 models hard, but grow its underlay material often can process proper form beforehand, simple treatment needs to be able to gift only after waiting for diamond film to grow the figure with diamond small exacter structure and dimension, decide the small structure of appearance to partial spy, this can yet be regarded as compares ideal one kind shape technology. The data that can be used at making model underlay basically is glass of silicon He Guangmin, because they process the form of need more easily,this basically is, and diamond can be in its surface deposit, in the meantime, underlay material can engrave corrode to get rid of conveniently after deposit diamond, make formation diamond small structure can be released optionally thereby. Lift diamond of a preparation the example of chamfer of tile fiber-optic alignment more be helpful for showing whole process. Corrode is engraved to be able to engrave corrode to give a series of V slot conveniently through film of oxidation silicon attack by surprise, anisotropy in the surface of monocrystalline silicon or the columnar and raised line that cross section is echelon. The structure after above narrates treatment is a mould, to its by groovy method the surface undertakes nucleate enhances activation (coarse change) deposit diamond is filmy, after achieving set ply, can be opposite according to need complex component part makes a few simple treatment, use the silicon matrix that local or full take out regards the chemical method that engrave corrode as the mould next, can get the V of diamond film structure with distinctive function chamfer. Use photosensitive glass to regard a mould as material likewise effective. From treatment process can see, the configuration that can come true is simpler, applied limits is restricted. A kind of duplicate craft that is based on model of SOI underlay silicon extended its process capability, can make two diamond film forms such as diamond the small structure with capillary more complex geometric ratio. The pattern of silicon small structure that this craft uses SOI substrate preparation to be made with Yu Fu, make be cut off by oxidation silicon between silicon small structure and underlay silicon, next according to before narrate film of diamond of same technology deposit, engrave silicon of matrix of corrode take out from backside then, the protection of separator of silicon of oxidation of have the aid of makes as the silicon of the mould small structure reservation comes down, give birth to long diamond film again in exposed the reverse side likewise, use finally corrode the quarter corrode dose with very high rate to corrode clip the silicon small structure between two diamond film, can get the diamond with exact size hollow small structure, a typical case is efficient the chip of refrigeration of diamond conduit miniature that conduct heat. Both treatment principle. The model duplicates to want to destroy matrix silicon normally, suit to make independent small structure quite, as compositive as other part have certain difficulty, sequel is machined also small processing technique of hang on other, so, its use is limited. 5 plasma engrave corrode technology common small rigid structure always is OK by grows optionally and treatment of two kinds of ways makes quarter corrode, diamond small structure is not exceptional also, the diamond small structure that introduces in front grows optionally and craft of preparation of laser beam machining is to have representative small processing technique. But, because diamond film gives birth to the characteristic of chief condition, grow of area form ability decision by the nucleus of initiative surface optionally, without the tie of film of limit attack by surprise. As the addition of filmy ply, its side direction grows unavoidable, accordingly, reduced this craft treatment to shape significantly the dimension precision of small structure, the blame activation area that at the same time still thick film grows to arise possibly is few and far between nucleus grows continuously the structural adhesion that causes, so, grow optionally the technology all is not like person meaning. Laser ablation small treatment also engraves corrode to differ with common dry law, use more stimulate means of scanning of beam of light to undertake, improve fine line process capability further besides need besides, treatment efficiency also rises urgently. Compare with them, the reaction ion that plasma of have the aid of undertakes engraves corrode to should have more advantages. Be not realise the potential dominant position that uses plasma to engrave corrode technology to machine diamond without the person, bello think RIE method should can react with what measure the least medium, realize the quarter corrode ability of better size control effect and anisotropy, because this is,advance diamond small parts of an apparatus to develop the task that must solve above all. However the interaction mechanism that what the research work more before this pays close attention to is plasma and diamond surface, the diamond film that majority studies to the job is aimed at the film that do not have attack by surprise merely undertakes, do not involve a graph to change place must the influence that stuff of film of attack by surprise cuts corrode to reaction ion, lack is accordingly practical. The person such as Sandhu studied the reaction ion of the O2 of diamond surface and H2 engraves corrode. Experimental discovery, flow from bias voltage and the aeriform sort with indoor reaction to concern continuously, and the case that leaves oxygen in same technology condition is compared hydric should big; In atmospheric pressure 6.

The natural Ⅱ that the carbolic film that 560Å/min won below 5Pa and the craft condition of 80ml/min oxygen throughput engraves corrode rate and 350Å/min - the quarter corrode rate of A diamond; Quarter corrode rate wants the RIE that hydrogenous RIE engraves corrode rate to compare oxygen low; The content that adds argon in gas mixture won't have any adverse effects to cutting corrode rate. The Bello reaction effect that studied heater plasma and microwave plasma environment issue a variety of quarter corrode gas, consider to make clear, in hydrogen plasma atmosphere falls, the electronic bombard that bias voltage place brings about does not make quarter corrode rate rises, and the ionic bombard of drive of bias voltage place just is the account that quarter corrode rate adds, pass diamond surface graphitization and its action mechanism has. Introduce argon gas to be able to increase the strength of ionic bombard, raise quarter corrode rate thereby, the harm that also raises pair of diamond appearances at the same time degree. Increase to what hydrogen joins partial oxygen in gas and do not cause quarter corrode rate certainly, bring about those who carve corrode reaction pattern to transform completely however. The Xe+ that Efremow uses 2keV is ionic bundle of diamond ion that goes with inpour of gas of reactivity of 2 oxidation nitrogen is auxiliary etch, etch rate changes from the 500Å/min when 100 ℃ the 2000Å/min when 0 ℃ , compare with the choice engraving corrode of film of aluminous attack by surprise for 20; Timothy uses argon and oxygen ion bundle quarter corrode diamond is filmy, discover oxygen is splashed ionicly shoot rate along with ion bundle an angle of incidence and change, and oxygen ion energy by 0.

When 5keV increases 1keV, splash shoot rate do not increase. What place of metallurgy of Shanghai of Chinese Academy of Sciences tries to use Kaufman source is ionic bundle of quarter corrode machine is filmy to diamond the treatment effect that makes engraving corrode to machine was takinged compare satisfaction, quarter corrode rate is 26 ~ 30nm/min, diamond and the quarter corrode choice with aluminous film of attack by surprise are than making an appointment with 10, the picture of lens of local scanning report that gets small structure from place looks, the sidewall of quarter corrode is steeper straight, this also is understandable, because of ion bundle it is better to can come true bundle shed directional control, be helpful for aggrandizement engraving the anisotropy feature of corrode. The effort that cuts small structure of corrode preparation ideal with RIE is in with nickel remarkable success perhaps was scored when nickel titanium alloy regards film of attack by surprise as material. Adopt chemistry of film of attack by surprise to engrave corrode or film of attack by surprise eletroplates the nickel titanium of craft preparation or film of nickel attack by surprise engrave corrode in majority taller quarter corrode is had to choose to compare below the condition, among them film of nickel titanium alloy does not need felt layer as film of attack by surprise, treatment craft is relatively simple, quarter corrode is compared in 25 ~ 32 between, and film of attack by surprise eletroplates the film of attack by surprise that combines the alternative chemical preparation that engrave corrode needs to be between diamond film and film of nickel attack by surprise offer felt layer, assure effective adhesion very hard otherwise, this increased the complexity of treatment on certain level. But, the technological process of reasonable combination can assure the precision that graph of film of attack by surprise transfers adequately, this small to careful diamond structure treatment especially important, the option engraving corrode that its can obtain is compared in 16 ~ 22 between, likewise OK and contented small structure engraves the need of corrode. Nickel and the advantage that titanium alloy regards nickel as stuff of film of attack by surprise still depend on them producing the effect of sidewall passivation possibly in quarter corrode process. The system that passes influencing factor of pair of quarter corrode process studies, established the range of P craft parameter that the favorable result that engrave corrode achieves below conditions of afore-mentioned film of attack by surprise, below drive of power of moderate strength radio frequency, actuating pressure 6 ~ 8Pa, working gas oxygen flow control is controlled in 80sccm, can make diamond film engraves corrode to achieve optimal result, the sidewall of diamond small structure is steep straight and smooth, engrave corrode happening without clear side direction, size control of the structure in graphical move process is accurate, the odd-come-short after quarter corrode is less also, quarter corrode rate is in 30 ~ between 50nm/min, make an appointment with of the system from bias voltage for 400 ~ 600V. The system considers to make clear, so ideal quarter corrode effect is potential profit from engraves corrode reaction system from passivation ability, right now this system is in a kind delicate cut corrode position from passivation. Conjectural mechanism is as follows: The metallic nickel that regards film of attack by surprise as material nickel titanium is managed to engrave corrode by measurable surface features and perhaps produce metallic oxide, the diamond surface that deposit is in all exposure, form the effect of film of small attack by surprise, diamond film was restrained to engrave corrode to react continuity undertakes on certain level, achieve the result of local passivation in the sidewall of small structure thereby, side direction was restrained to cut the course of corrode on certain level, make sidewall steep thereby straight. However, the quarter corrode area in film of passivation of oxide of likewise deposit metal is bottom, because have the ion with certain directional level bundle direct bombard strength is apparent the sidewall of prep above small structure, directional come from at the action from bias voltage, passivation layer can be kept clear of ceaselessly, lose thereby stop action, so, the inhibition that the quarter corrode process of perpendicular direction gets is less, can get finally having the quarter corrode result of apparent anisotropy. Small to engraving surface of parietal of small structure of the diamond after corrode divisional analyse is preliminary the rationality that proved afore-mentioned speculation, the small structure parietal that for film of attack by surprise with nickel quarter corrode gets Russia rests can chart analysis shows the oxidation nickel that has outstanding amount exists, and the sample that is film of attack by surprise with nickel titanium alloy detects at the same time the existence of oxidation nickel and oxidation titanium, show passivation film namely really flank of consist in small structure, and working requirement area is narrated before confirming they come from the deviate of the reaction that engrave corrode at stuff of film of attack by surprise, quarter corrode effect can become poor apparently. Too low job atmospheric pressure can bring about a system to rise of bias voltage significantly oneself, the component that makes physics engrave corrode increases, make quarter corrode rate falls, small structure sidewall injures aggravate, quarter corrode odd-come-short increases; Conversely, if systematic work is baric exorbitant, criterion as the systematic fall from bias voltage, physics engraves the effect of corrode to reduce, sidewall passivation effect becomes poor, side direction engraves corrode gradually apparent, in the meantime, film of bottom small attack by surprise also cannot be kept clear of in time quite gradually, occurrence bottom is then long " careless " phenomenon, this is considered as small attack by surprise to film cannot be kept clear of adequately quite and accumulate the result that creates gradually normally. RIE engraves corrode craft than before narrate grow optionally, the model duplicates and stimulate the applicability with older than having photograph of photoetching corrode technology and stronger thick film process capability, use this technology not only can create the simple small structure such as cantilever bridge, filmy gear conveniently, and the attempt machines diamond small hinge and still score initial success, more important is RIE engraves corrode to machine groovy technology measure imperceptibly therefore, compatibility of as small as other processing technique is good, can get used to diamond better small structure is compositive production long-term goal. The mechanical performance that film of 6 conclusion diamond stresses because of its makes MEMS system likely most important structural function material, one of main difficult problem that puzzle its to popularize application -- personal computer fetterses processing technique, it is certain that evolutional foundation is obtained to go up in a variety of crafts get understanding on degree definitely. The requirement that is aimed at different object and actual condition choose proper treatment technology, the use requirement of treatment of small structure of already OK and basic contented diamond and development of its MEMS parts of an apparatus, among them the oxygen reaction ion of film of metallic attack by surprise engraves corrode technology to provide extensive applicability most, and quarter corrode equipment popularizes RIE relatively relatively, believe afore-mentioned jobs are in after getting extensive acknowledge, will be in to diamond film in MEMS system since application to strong propulsion action. CNC Milling CNC Machining