CN1278612A - Low temperature metalization process of preparing thick film photoetching glue - Google Patents

Abstract

The low-temp, metallization preparation method of thick film photoresist is characterized by that on the surface of one side of polymer film, for example polymethyl methacrylate PMMA it adopts the methods of magnetic control sputtering, etc. to form metal seed layer whose low-temp. settled thickness is 10-100 nanometers, then the metallized side surface of the obtained metallized film is stuck together with metal or glass base body, and then the polymer film can be thinned. Its metal conductive support layer can be single-metal film, also can be metal or alloy multi-layer film. Said invention is stable and reliable in technological process, and its preparation efficiency and finished product rate can be raised.

Description

The low temperature metalization process of preparing of thick film photolithography glue

The present invention relates to a kind of preparation method of thick film photolithography glue, relate in particular to a kind of thick film photolithography glue preparation method, belong to the micro-processing technology field based on the low temperature metalization technology.

In recent years, deep day by day along with Micro Electro Mechanical System and correlation technique research thereof, LIGA (the abbreviation of German LITHOGRAPHIE, GALVANOFORMUNG and ABFORMTECHNIK, referring to photoetching, plating and model copy respectively) technology also makes significant progress, be applied in various fields, bringing into play unique effect.It is advantageous that its high aspect ratio microstructures working ability, and high aspect ratio microstructures derives from the degree of depth photoetching of thick film photolithography glue, therefore, thick adhesive process is one of key of LIGA technology.

The photoresist of LIGA technology is the most commonly used with polymethylmethacrylate (PMMA), for thickness at the photoresist below 400 microns, general liquid photoresist casting way preparation (the J.Mohr et al on specialized substrates that adopts, Requirements on resist layers in deep-etch synchrotronradiation lithography, J.of vacuum science ﹠amp; Technology B, 6 (6), 1988,2264～2267), if wish that photoresist thickness is obviously greater than 400 microns, above-mentioned technology will be difficult to be competent at, because there is volumetric contraction to a certain degree in photoresist in the injection molding solidification process, thereby causes the moulding photoresist that sizable tension stress is arranged, thick glue may cause serious flexural deformation of substrate even damage, also may make the photoresist of curing produce a large amount of micro-cracks, can't use at all.

Yet, the advantage of LIGA technology mainly is its thick glue working ability, thick adhesive process can't be avoided, the way of dealing with problems at present adopts thick film barbola work (B.Chaudhuri et al, Photoresistapplication for the LIGA process, Microsystem Technologies4 (1998), 159～162).

This technology at first selects to use the commodity PMMA diaphragm of synchrotron radiation X-ray light source exposure (as Goodfellow, AIN plastics, the product of companies such as ATO-Haas), behind special process thermal treatment and finish-drying, make bonding agent with a small amount of PMMA monomer solution, paste on the special conductive substrates carefully, because good combination power and electric conductivity are the prerequisites of follow-up little electroforming process, so, at present only have substrate few in number can satisfy above-mentioned requirements simultaneously, alternative leeway is very little.Insulation at a certain temperature makes the solvent in the bonding agent slowly spread through the PMMA diaphragm then, cuts the throwing method and will adhere to the thickness that diaphragm on the substrate is thinned to hope and get final product with rotating at last.The present thick glue of LIGA technology more than 400 microns generally all according to this technology complete.

This technology can not be eliminated the excessive drawback of photoresist internal stress fully in fact, because the time with the bonding photoresist diaphragm of PMMA monomer solution, solvent in the bonding agent is by being absorbed by the diaphragm inboard earlier, the mode of emitting from the outside is volatilized again, not only process is slow, and can cause the variation of diaphragm physical dimension inevitably, expand earlier, shrink again, can cause the generation of internal stress equally, the internal stress that different is here is higher to the susceptibility of process conditions, controls just rightly, can obtain the result than low internal stress, in case a certain step operation is improper in the technological process, just can cause internal stress to enlarge markedly, and the picture adhesive consumption, solvent evaporates degree in the bonding process, the accurate control of factors such as adhesive layer thickness is very difficult, adds that the operability of lamination process is relatively poor, cause photoresist diaphragm and conductive substrates adhesion to be difficult to guarantee, the technology success ratio is lower, and big to the dependence of operating experience, difficulty of processing is higher.

The objective of the invention is to above-mentioned deficiency, a kind of new thick film photolithography glue preparation method is provided,, improve bonding effect, and technology is simple, reliable and stable, improve preparation efficiency and yield rate to reduce internal stress at prior art.

For realizing such purpose, the present invention proposes a kind of low temperature metalization process of preparing of thick film photolithography glue, prepare thick film photolithography glue by polymer film low-temperature metal metallization processes.Basic process is as follows: select the above polymer membrane of thickness 1mm, as commodity PMMA diaphragm, be divided into the size that needs, cleaning traditionally, dry and thermal treatment, then at one side surface depositing electrically conductive supporting layer, reach side metallization purpose, then be bonded into one with metallized one side of polymer membrane and thicker metal or glass substrate, cut milling method with rotation at last polymer membrane is carried out attenuate, just can obtain the thick film photolithography glue of any thickness, general thickness is between 200 microns to 2 millimeters.

Metallization processes of the present invention should be tried one's best and be finished at a lower temperature, can multiple choices such as plasma deposition method, chemical plating method and coated with conductive gluing method be arranged metallization approach for you to choose, but require conductive coating and selected polymkeric substance that firm combine and can be as the initial layers of little electroforming arranged.Because magnetron sputtering helps obtaining good combination power most, should be to select preferably, but the common speed of sputtering sedimentation is slower, can first sputtering sedimentation one layer thickness be the metal seed layer of ten to 100 nanometers therefore, then thickeies fast to 1～3 micron with electro-plating method.Consider adhesion and the effect of electroforming initial layers of taking into account, the metallic conductivity supporting layer not only can be the monometallic film, and the MULTILAYER COMPOSITE membrane structure of metal or alloy often more can be competent at, such as Cr/Cu, Cr/Ni, Cr/Au, Ti/Ni etc.Bonding agent should selection contain the epoxy resin or the silica gel of volatile component, can guarantee can not come off in the thinning process and get final product, substrate is advisable with metal or glass equal strength height, the good material of thermal conductivity, can reduce substrate thickness like this, improve the heat evacuation capacity of thick glue in photoetching or reactive ion etching process.

The present invention is equally applicable to process other polymer membrane except that PMMA, as polyimide (PI), PS (polyester), PE (tygon) and PP (polypropylene) or the like, the LIGA technology that also the can be used as photoresist that has after these Polymer Processing, what have can be used for other accurate LIGA technology, as deep reaction ion etching (DRIE)/laser LIGA etc., the preparation high aspect ratio microstructures.

The present invention and the existing direct barbola work of PMMA diaphragm have essential distinction, at first, metal conducting layer directly deposits on the polymer membrane, suitably selection can guarantee thin polymer film and bond strength as the metal film of little electroforming initial layers, microstructure is unlikely after guaranteeing to process comes off, and alternative metallized dielectric is many, can be the monometallic film that good combination power is arranged with PMMA, also can further improve bond strength by transition bed; Secondly, bonding agent no longer must be the monomer of PMMA, because bonding agent be in little electroforming initial layers below, no longer need to have photoperceptivity, so, the choice is very big, can use not solvent-laden any bonding agent, such as the epoxy resin adhesive, there is not the problem of solvent diffusion, also can tolerate such as micro-pore even the disappearance of bonding agent among a small circle simultaneously, under the situation that does not need attenuate, even do not need to be bonded in the thicker substrate, just can be directly used in exposure, the failure of having avoided bonding to be caused substantially; The 3rd, backing material need not special processing, and bigger choice is arranged.Guarantee that it is the stable condition precedent of processing back high aspect ratio microstructures that substrate and polymer membrane have enough adhesions, it also is the prerequisite of follow-up little electroforming processing, for this reason, existing substrate must have the titanium dioxide or the cupric oxide surface of special processing, above-mentioned necessary adhesion is guaranteed, and so in the present invention, the integrated support effect to polymer membrane is only played in substrate, metalized surface by common adhesive and polymer membrane is bonding, just can reach request for utilization.In view of the foregoing, the present invention has eliminated may cause the unusual major influence factors that increases of internal stress in the photoresist preparation process, a difficult problem of having avoided bonding effect influence processing back microstructure and substrate caking power, avoided complicated substrate process, process stabilizing is reliable, from having solved the technical barrier that influences yield rate in essence.

Embodiment

Cut-off footpath 50mm, the PMMA thin slice of thick 1mm, isopropyl alcohol cleans, purify air and dry up, on the one side surface, deposit 10nm Cr earlier with Z-550 magnetron sputtering machine after the thermal treatment, deposit 40nm Ni again, flash plate nickel is thickeied to 2.5 microns in the watt nickel plating solution then, take out and clean and air drying, be bonded together with clean 3 inches glass substrates with epoxy adhesive 504 glue of the commodity one side that will metallize, after treating that bonding agent solidifies, cut milling method with rotation and be thinned to 400 microns, just can be used for synchrotron radiation exposure or the little processing of other high aspect ratio structure.

Claims (6)

1, a kind of low temperature metalization process of preparing of thick film photolithography glue, it is characterized in that selecting the above polymer membrane of thickness 1mm, be divided into the size that needs, through cleaning, dry also thermal treatment, adopt magnetron sputtering that diaphragm one side is metallized then, promptly at a lower temperature to diaphragm one side surface depositing electrically conductive supporting layer, elder generation's sputtering sedimentation one layer thickness is the metal seed layer of 10 nanometers～100 nanometers, thicken fast to 1～3 micron with electro-plating method again, with cementing agent the metallized one side of polymer membrane and metal or substrate of glass are bonded into one afterwards, cut milling method with rotation at last polymer membrane is thinned to 200 microns～2 millimeters.

2,, it is characterized in that said diaphragm one side surface metallization processes can also adopt other low temperature plasma deposition process, chemical plating method and coated with conductive gluing method etc. as the low temperature metalization process of preparing of the said thick film photolithography glue of claim 1.

3,, it is characterized in that said polymer membrane can be polymethylacrylic acid PMMA, polyimide PI, polyester PS, polythene PE or polypropylene PP etc. as the low temperature metalization process of preparing of claim 1 or 2 said thick film photolithography glue.

4, as the low temperature metalization process of preparing of claim 1 or 2 said thick film photolithography glue, it is characterized in that said metallic conductivity supporting layer can be the monometallic film, also can be the multilayer film of metal or alloy, as Cr/Cu, Cr/Ni, Cr/Au, Ti/Ni etc.

6,, it is characterized in that said bonding agent selection does not contain the epoxy resin or the silica gel of volatile component as the low temperature metalization process of preparing of claim 1 or 2 said thick film photolithography glue.

5,, it is characterized in that said substrate employing intensity height, thermal conductivity good metal or glass etc. as the low temperature metalization process of preparing of the said thick film photolithography glue of claim 1.