Background technique
With being constantly progressive for semiconductor device fabrication process, traditional wire bonding mode is just gradually by new bonding workReplaced skill, for chip bonding, wherein ball upper contact bonding (BSOB) technology has been widely used in chipBonding in.
BSOB technology includes the beginning of weld cycle, and soldering appliance (chopper) is moved to the position of the first spot welding, and firstSpot welding realizes that a metal ball is welded on chip bonding pad surface by heat and ultrasonic energy, and chopper is increased to the top of bank laterPosition and the mobile bank form for forming needs, the second spot welding include stitch bond and draw buttock line, drawn after being bondedButtock line is that the formation in order to form a buttock line, for next bonding recycle metal ball is prepared.
Be using the advantages of BSOB technology: 1) temperature of metal ball is high, and good deformation is more readily formed in when bonding, withPad generates reliable interconnection；2) metal ball is relatively large in diameter, and can increase adhered area, improves bond strength；3) metal ballSonic oscillation, pressure can be prevented to be directly applied to chip surface, antidetonation protective effect is played to chip.
After leading wire bonding, after appearance test, wire bonding tensile test, performance of integrated circuits test passes, thenCarry out sealing cap.But this technology is primarily present following problem: 1) when leading wire bonding pulling force mistake occurs in outer lead end faceWhen low or rosin joint, for civil product, point solder carries out physics reinforcing at bonding point, for technical grade, army grade, aerospaceGrade product, then directly scrap or the use that degrades；2) when too low leading wire bonding pulling force or rosin joint occurs in chip surface pad, byIt in the reasons such as undersized, can not reinforce, then directly scrap or the use that degrades；3) for multilead integrated circuit, as long as whereinThere is bonding quality problem in a piece lead, will make entire product overall degradation or scrap, cause damages.
Adhesion strength between the metal ball formed using above-mentioned BSOB technology and pad still has certain deficiency, causesRemoving between metal ball and pad, in turn results in semiconductor device failure.Currently, to solve the above-mentioned problems, application No. is200510003089.8 patent application increases electroplating work procedure before dress knot chip and pressure welding, and electroplating work procedure is with the side being sandedMethod removes the original metal layer in lead styletable face, then electronickelling, only the lead post part of plating integrated circuit pedestal, ShenNumber the active force between pad and metal ball please be reinforced using high temperature process for 201210246504.2 patent application, but onIt states that method is comparatively laborious, especially applies in the stringent chip of structural requirement, plating or high-temperature heating method mayThe semiconductor structure formed is had an impact.
Summary of the invention
The application is intended to provide a kind of wire bonding structure and wire bonding method, with do not influence existing chip structure andSolve the problems, such as that metal ball is easily peeled off with pad in the prior art on the basis of performance.
To achieve the goals above, according to the one aspect of the application, a kind of wire bonding structure is provided, comprising: welderingDisk；Metal ball is fixed on pad；Bonding wire is wholely set with metal ball, the contact surface that pad is contacted with metal ball pointIt is furnished with multiple recessed portions.
Further, the area ratio on the surface of above-mentioned contact surface and the separate metal ball of pad is 1.5:1~1.2:1.
Further, the depth of above-mentioned recessed portion is 50nm~100nm.
Further, above-mentioned pad is aluminum pad, and metal ball is gold goal or copper ball, and bonding wire is gold thread or copper wire.
According to further aspect of the application, a kind of wire bonding method is provided, wire bonding method includes: stepPad is arranged in S1；Step S2 carries out ion bombardment to the surface of pad and forms recessed portion；And step S3, bonding wire is led toSurface bond after crossing metal ball and ion bombardment.
Further, above-mentioned steps S2 uses argon ion bombardment.
Further, the rf frequency of above-mentioned ion bombardment is 13.56MHz, and the time of ion bombardment is 15s~30s.
Further, radio-frequency power 600W~800W of above-mentioned argon ion bombardment, the flow of argon ion is 500~600sccm。
Further, above-mentioned steps S3 is implemented by the way of ultrasonic bond or thermocompression bonding.
Further, above-mentioned steps S3 includes: step S31, heats one end of bonding wire to form metal ball；StepS32 by the surface after the bombardment of metal ball contact ions and presses to metal ball, the surface after making metal ball be fixed on ion bombardmentOn.
Further, above-mentioned pad is aluminum pad, and metal ball is gold goal or copper ball, and bonding wire is gold thread or copper wire.
Using the technical solution of the application, multiple recessed portions are set on the surface of pad contacted with metal ball, in turnThe contact area between pad and metal ball is increased, and replaces original plane contact using the curved face contact of the application, is increasedAdd resistance when removing between pad and metal ball, and then efficiently solves the problems, such as the two removing；In addition, the application is onlyIt is to be improved to the surface texture of pad, does not need to form amount of heat to newly using techniques such as high-temperature heating, platingThe semiconductor device structure of formation generates any influence, therefore ensure that the original structure and function of chip.
Specific embodiment
It is noted that following detailed description is all illustrative, it is intended to provide further instruction to the application.Unless anotherIt indicates, all technical and scientific terms used herein has usual with the application person of an ordinary skill in the technical fieldThe identical meanings of understanding.
It should be noted that term used herein above is merely to describe specific embodiment, and be not intended to restricted rootAccording to the illustrative embodiments of the application.As used herein, unless the context clearly indicates otherwise, otherwise singularAlso be intended to include plural form, additionally, it should be understood that, when in the present specification using belong to "comprising" and/or " packetInclude " when, indicate existing characteristics, step, operation, device, component and/or their combination.
For ease of description, spatially relative term can be used herein, as " ... on ", " ... top "," ... upper surface ", " above " etc., for describing such as a device shown in the figure or feature and other devices or spyThe spatial relation of sign.It should be understood that spatially relative term is intended to comprising the orientation in addition to device described in figureExcept different direction in use or operation.For example, being described as if the device in attached drawing is squeezed " in other devicesIt will be positioned as " under other devices or construction after part or construction top " or the device of " on other devices or construction "Side " or " under other devices or construction ".Thus, exemplary term " ... top " may include " ... top " and" in ... lower section " two kinds of orientation.The device can also be positioned with other different modes and (is rotated by 90 ° or in other orientation), andAnd respective explanations are made to the opposite description in space used herein above.
As background technique is introduced, the adhesion strength between the metal ball that existing BSOB technology is formed and pad is still depositedIn certain deficiency, lead to the removing between metal ball and pad, in turn results in semiconductor device failure, and current reinforcing is drawnBetween line and pad the method for adhesion strength it is cumbersome and it is easy established semiconductor structure is impacted, in order to not influenceHave and solves the problems, such as that metal ball is easily peeled off with pad in the prior art on the basis of chip structure and performance, present applicant proposesA kind of wire bonding structure and wire bonding method.
In a kind of preferred embodiment of the application, a kind of wire bonding structure is provided, it as depicted in figs. 1 and 2, shouldWire bonding structure includes pad 100, metal ball 200 and bonding wire 300, and metal ball 200 is fixed on pad 100；Lead300 are wholely set with metal ball 200, wherein recessed portion is distributed in the contact surface of pad 100 contacted with metal ball 200101。
Wire bonding structure with above structure is arranged multiple on the surface of pad 100 contacted with metal ball 200Recessed portion 101, and then the contact area between pad 100 and metal ball 200 is increased, and replace using the curved face contact of the applicationOriginal plane contact is changed, increases resistance when removing between pad 100 and metal ball 200, and then efficiently solve twoThe problem of person removes；In addition, the application is improved to the surface texture of pad 100, do not need using high-temperature heating, electricityThe techniques such as plating form amount of heat and generate any influence to the semiconductor device structure newly formed, therefore ensure that chipOriginal structure and function.
The application in order to increase the contact area of pad 100 Yu metal ball 200 as much as possible, preferably above-mentioned contact surface withThe area ratio on the surface of the separate metal ball of pad is 1.5:1~1.2:1.In addition, in order to increase pad 100 and metal as far as possibleResistance when removing between ball 200, the depth of preferably above-mentioned recessed portion 101 are 50~100nm.
The above-mentioned wire bonding structure of the application, the improvement that the wire bonding suitable for this field routine combines, wherein originallyApply for that preferably above-mentioned pad 100 is aluminum pad, preferably above-mentioned metal ball 200 is gold goal or copper ball, preferably above-mentioned bonding wire 300For gold thread or copper wire.
In the application another preferred embodiment, a kind of wire bonding method is provided, Fig. 3 shows the leadThe flow diagram of bonding method, the wire bonding method include: step S1, and pad 100 is arranged；Step S2, to pad 100Surface carries out ion bombardment and forms recessed portion 101；And step S3, bonding wire 300 is passed through into metal ball 200 and ion bombardmentSurface bond afterwards.
Above-mentioned wire bonding method utilizes the surface of the ion bombardment pad 100 in plasma, which can interruptChemical bond between 100 surface atom of pad, these atoms will be exposed in free radical caused by plasma, then from pad100 surfaces are detached from, and then generate recessed portion 101 in the position of ion bombardment, so that the surface of pad 100 becomes concave-convex from planeSurface, the area of convex-concave surface are greater than original plane, that is to say, that after ion bombardment pad 100 and metal ball 200 itBetween contact area increase, while resistance when removing between pad 100 and metal ball 200 also increases, and then effectivelySolves the problems, such as the two removing.In addition, the direction of ion bombardment is hung down with the surface bombarded as well known to art technologyDirectly, that is to say, that as long as the guarded by location for not needing ion bombardment, which is got up, to have an impact existing semiconductor structure,Therefore, above-mentioned production method will not generate any negative effect.
Now, the illustrative embodiments according to the application are more fully described with reference to the accompanying drawings.However, these are exemplaryEmbodiment can be implemented by many different forms, and should not be construed to be limited solely to embodiment party set forth hereinFormula.It should be understood that it is thoroughly and complete to these embodiments are provided so that disclosure herein, and these are shownThe design of example property embodiment is fully conveyed to those of ordinary skill in the art, in the accompanying drawings, for the sake of clarity, expands layerWith the thickness in region, and make that identical device is presented with like reference characters, thus description of them will be omitted.
It should be appreciated by the person skilled in the art that the wire bonding structure and wire bonding method of the application can be appliedDuring any integrated antenna package, below in order to more clearly illustrate the application wire bonding structure and wire bonding sideThe effect of method preferably to be bonded in the conventional enterprising line lead of metal interconnection structure, and is formed and metal interconnection structure couplingWire bonding structure.The following description is also to be illustrated with the scheme for carrying out wire bonding with metal interconnection structure, can notFor limiting, explaining the application of the wire bonding structures and methods of the application.
Firstly, executing step S1, pad 100 shown in Fig. 4 is set.It should be appreciated by the person skilled in the art that metalInterconnection structure 1 is coupled by wire bonding and external lead frame, and above-mentioned pad 100 should be with the metal of metal interconnection structure 1Portion 11 is attached, i.e., pad 100 is arranged in the top with metal portion 11 of metal interconnection structure 1.Above-mentioned pad is set100 process includes:
Passivation layer is set on the surface of metal interconnection structure 1；Then the passivation layer is performed etching, is mutually linked in metalThe top with metal portion 11 of structure 1 forms opening；Then into the opening with deposited metal material on passivation layer and to metalMaterial carries out chemical-mechanical planarization (CMP), forms pad 100 shown in Fig. 4.The above process can be using this field routineDeposition, etching, the condition of CMP carry out, and details are not described herein.The material for forming above-mentioned pad can use the material of this field routineMaterial, the preferred metallic aluminium of the application.
Then, step S2 is executed, ion bombardment is carried out to the surface of pad 100 shown in Fig. 4 and forms recess shown in fig. 5Portion 101.The ion bombardment of the process is the surface for pad 100, therefore can be to set on 100 surface of pad shown in Fig. 4Photoresist layer 3 is set, processing then is patterned to photoresist layer 3 and is open with being formed in the top of pad 100, then in photoetchingThe surface exposed to pad 100 carries out ion bombardment under the protection of glue-line 3, is formed on 100 script even curface of pad recessedConcave portion 101.
The ion bombardment of above-mentioned steps S2 preferably uses argon ion bombardment, and argon gas is inert gas, in ion bombardment processIn will not generate decomposition collision, therefore excessive corrosion will not be generated to 100 surface of pad.
When selecting above-mentioned argon ion bombardment, the rf frequency of preferably above-mentioned ion bombardment is 13.56M Hz, ion bombardmentTime is 15~30s.
The application in order to formed depth be 50~100nm recessed portion 101, the preferably radio-frequency power 600W of argon ion bombardment~800W, the flow of argon ion are 500~600sccm.
After forming convex-concave surface 101, after bonding wire 300 is passed through metal ball 200 and ion bombardment shown in fig. 5Surface bond, form wire bonding structure shown in fig. 6.
Above-mentioned bonding process can be real by the way of ultrasonic bond commonly used in the art, thermocompression bonding or the raw bonding of heatExisting, preferably above-mentioned steps S3 is implemented by the way of ultrasonic bond or thermocompression bonding.Wherein, it is excellent when bonding wire 300 is gold threadChoosing uses thermocompression bonding, and being formed by metal ball 200 is gold goal；When bonding wire is copper wire, it is preferred to use ultrasonic bond, institute's shapeAt metal ball be copper ball.
In another preferred embodiment of the application, the step S3 of above-mentioned wire bonding method includes: step S31,One end of bonding wire 300 is heated to form metal ball 200；Step S32, by the surface after the bombardment of 200 contact ions of metal ballAnd press to metal ball 200, on the surface after making metal ball 200 be fixed on ion bombardment.Using hot pressing after above-mentioned first hot meltThe metal of metal ball 200 and pad 100 can be formed metallurgical bonding, form more strict welding structure by mode.
It can be seen from the above description that the application the above embodiments realize following technical effect:
1), multiple recessed portions are arranged on the surface of pad contacted with metal ball in the wire bonding structure of the application, intoAnd the contact area between pad and metal ball is increased, and original plane contact is replaced using the curved face contact of the application,Resistance when removing between pad and metal ball is increased, and then efficiently solves the problems, such as the two removing；
2), the application is improved to the surface texture of pad, is not needed using techniques such as high-temperature heating, plating,It avoids these techniques and forms amount of heat to the semiconductor device structure generation any influence newly formed, therefore ensure thatThe original structure and function of chip；
3), the direction of above-mentioned ion bombardment is preferably vertical with the surface bombarded, that is to say, that as long as ion will not neededThe guarded by location of bombardment, which gets up, to have an impact existing semiconductor structure, and therefore, above-mentioned production method, which will not generate, appointsWhat is negatively affected.
The foregoing is merely preferred embodiment of the present application, are not intended to limit this application, for the skill of this fieldFor art personnel, various changes and changes are possible in this application.Within the spirit and principles of this application, made any to repairChange, equivalent replacement, improvement etc., should be included within the scope of protection of this application.