WO2015022193A1

WO2015022193A1 - Electrical component with an area to be contacted electrically and method for preparing an electrical component for a connection process

Info

Publication number: WO2015022193A1
Application number: PCT/EP2014/066430
Authority: WO
Inventors: Christoph Regula; Ralph Wilken; Jörg IHDE; Jost Degenhardt
Original assignee: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date: 2013-08-16
Filing date: 2014-07-30
Publication date: 2015-02-19
Also published as: DE102013216282A1; DE102013216282B4

Abstract

The invention relates to an electrical component with at least one area to be contacted electrically, wherein a plasma polymer matrix is arranged on this area, which matrix is an amorphous hydrocarbon layer or an SiO_x layer containing carbon. The invention further relates to a method for preparing an electrical component for a connection process and to the use of a corresponding plasma polymer matrix for preparing an area to be contacted electrically for a connection to a wire.

Description

Electrical component with a location to be electrically contacted and method for preparing an electrical component for a connection process

The invention relates to an electrical component having at least one point to be electrically contacted, wherein at this point a plasma polymer matrix is arranged, which is an amorphous hydrocarbon layer or a carbon-containing SiO _x layer. The invention also relates to a method for preparing an electrical component for a connection process as well as to the use of a corresponding plasma-polymer matrix for preparing a point to be electrically contacted for connection to a wire.

In a variety of technical fields electrical and / or electronic components are required, which must be electrically connected to each other. The requirements for this bonding (bonding, bonding) are greater, the smaller and more numerous the joints in an overall system. In particular, for a smaller binding site, the problem is that a relatively small area is available to produce a secure, electrically conductive contact. A large number of binding sites increases the likelihood that, in the case of non-optimal process management, single or multiple contacts can not be reliably established, which in the worst case makes the overall system non-functional or at least not reliable. Particularly in the field of wire bonding when connecting very small wires to - usually - very small contact points - the requirements are particularly high. In the context of this invention, "connection" or a connection process is understood to mean all processes for connecting a point of an electrical component to be electrically contacted to a wire or another suitable means, so that a current flow through the electrically contacting point is possible In general, the term "bonding" encompasses in particular sintering, welding, soldering, interfacial soldering and wire bonding.

Problems present to the soil are superficial oxide layers or areas that may appear at the sites prepared for bonding, thereby hindering the establishment of effective electrical contact. Therefore, in many cases, Ag or Au coated lead frames are used for wire bonding and / or organically coated lead frames to aid in the bonding process. Corresponding protective layers contribute to the fact that electrical components in which the contacts have not yet been made at points to be electrically contacted can also be stored for a longer period of time without a significant deterioration of the contactability occurring at the points to be contacted. It is important that the protective layers to be used include the contacting process (bonding process), e.g. soldering, interfacial soldering, wire bonding, welding or sintering, do not hinder or reduce its quality. Thus, for example, there is the danger that, due to the presence of a corresponding passivation layer, the resulting compound, although electrically contacting, comes about, but the mechanical load-bearing capacity of the connection is reduced.

References to passivation layers of the prior art are, for example:

U. Lommatzsch, J. Ihde, Plasma Process. Polym. 2009, 6, 642-648 and S. Sathiyanarayanan, S. Muthukrishnan, G. Venkatachari, D.C. Trivedi, Progress in Organic Coatings 53 (2005) 297-301

The object of the present invention was to provide an electrical component which is prepared in a particularly suitable manner for the production of electrical contacts at desired locations. Furthermore, in the context of the present task, it was preferably desirable for the electrical component to be accessible by means of a relatively inexpensive process, preferably an atmospheric pressure method, and also for as few processing steps as possible to prepare and process the points to be contacted. This object is achieved according to the invention by an electrical component having at least one point to be electrically contacted, a plasma-polymer matrix being arranged on this point

(i) is an amorphous hydrocarbon (a-C: H) layer measured by XPS comprising> 90 atomic% of elements C and O or

(ii) a C-containing SiO _x layer comprising 5 - 80 atom% C, preferably 8 - 60 atom% C, particularly preferably 10 - 40 atom% C, in each case based on the total number of all atoms of the plasma polymer Matrix without H and wherein the matrix has a layer thickness of 5-100 nm. An electrical component in the sense of this invention is a component that is designed to perform a function that does not involve or not only the transmission of electricity. In this case, electrical components in the context of this invention may be simple structures such as a resistor, but it may also be very complex structures such as electronic circuits.

In the context of this invention, a point to be electrically contacted is a point which is set up to be connected to a wire or another suitable means such that a current flow through the electrically contacting point is possible.

For the purposes of this invention, a plasma polymer matrix is to be understood as meaning a plasma polymer which differs materially from the material forming the binding site and at least partially surrounds the binding site. The term "matrix" is primarily a (partial) coating to understand.

The advantage of the electrical components according to the invention is that the contacting site is at least partially protected against oxidation by the plasma-polymer matrix. Surprisingly, it has been found that the matrix to be used according to the invention is particularly helpful in creating corresponding contacts.

It is preferred in this context that the plasma polymer matrix to> 95 atomic%, more preferably> 98 atomic% and particularly preferably completely from the specified elements (without H), each measured by XPS. It should be emphasized that small amounts of nitrogen, as z. B. in an atmospheric pressure coating are often found in the matrix, surprisingly, the advantages of the present invention to be used plasma polymer matrix does not significantly diminish. Nevertheless, it is preferable that the Nitrogen content in the matrix to be used according to the invention is <3 atom%, more preferably <1 atom%, based on the total number of all the atoms of the plasma polymer matrix (without H), preferably measured by XPS.

An a-C: H layer in the context of this invention is an amorphous hydrocarbon layer, it being preferred that this layer consists of> 95 atom% of the elements C and O (measured by means of XPS). a-C: H layers can even reduce the effect of metal oxides present on the sites to be contacted. Corresponding a-C: H layers can also be produced from atmospheric-pressure plasma during deposition under reducing conditions. This is also well-suited, for example, within the scope of the method disclosed in DE 10 2009 048 397 A1.

In a particularly preferred embodiment, the plasma polymer matrix contains no further (non-plasma polymer) components, i. the plasma polymer matrix consists of plasma polymer. In a further particularly preferred embodiment, metallic nanoparticles (particles having three outer dimensions in the range from 1 nm to 100 nm) are dispersed in the plasma-polymer matrix. Particular preference is given to particles having particle sizes of 1 to 20 nm. In this particularly preferred embodiment, the plasma polymer and the dispersed particles are present as separated phases. In the process of bonding (contacting), a continuous metallic phase is formed by sintering the dispersed metallic nanoparticles in the plasma polymer matrix. This can be demonstrated by checking with a continuity tester.

In this particularly preferred embodiment, the plasma polymer matrix is preferably an amorphous hydrocarbon (aC: H) layer as defined above. The nanoparticles preferably contain one or more metals from the group consisting of copper, silver and gold. The metals are each in the metallic, ie not oxidized state. Particularly preferred are nanoparticles consisting of copper, silver, nanoparticles consisting of intermetallic phases of copper and silver, nanoparticles consisting of gold and nanoparticles consisting of intermetallic phases of copper and gold. The concentration of the nanoparticles in the plasma polymer matrix is preferably 10 vol.% To 80 vol.%, Particularly preferably 40 vol.% To 70 vol.%, Based on the total volume of the plasma polymer matrix.

In the case of a plasma polymer matrix with nanoparticles dispersed therein (as described here), the embedded metallic nanoparticles should not be included in the determination of the atomic% fractions of the elements C, O, H, N and Si of the matrix, i. the atomic percentages of the elements C, O, H, N and Si relate exclusively to the plasma polymer fraction of the coating (matrix)

The nanoparticles preferably consist of the same metal as the part of the component to be contacted and / or the means (for example the wire) with which the component to be contacted is to be connected. Particularly preferably, the nanoparticles consist of the same metal as the part of the component to be contacted and the means (for example a wire) with which the part of the component to be contacted is to be connected. By sintering the metallic nanoparticles during bonding, i. upon contacting the part of the device to be contacted, a continuous metallic phase forms between the part of the device to be contacted and the means (e.g., a wire) to which the part of the device to be contacted is connected. This avoids the formation of intermetallic phases, which generally limits the reliability and lifetime of electronic components. An inventive electrical component is preferred, wherein the point to be electrically contacted consists of Cu or a Cu alloy. In particular with copper contacts, the plasma-polymer matrix to be used according to the invention develops its positive properties.

Accordingly, according to the invention, an electrical component is particularly preferred, wherein the plasma-polymer matrix has a passivating effect against oxide layers in the site (s) to be contacted.

"A passivating effect against oxide layers" means in connection with this application that the oxidation of the coated with the plasma polymer matrix according to the invention coated to be contacted to an uncoated to be contacted point of the same material under normal conditions, room temperature, atmospheric pressure, humidity of 20 ° C. ± 2 ° C, 65% RH ± 4% at 1013 hPa is slowed down, preferably the oxidation rate is only half as high and the oxidation is particularly preferred (in the range of Coating) completely inhibited. Even more preferably, the "passivating effect" even comprises a reducing action against already existing oxides.

As a result, annoying oxide layers are avoided for the connection process. In the case of reduction, of course, the respective oxide is reduced to the elemental metal.

The XPS measurement is the preferred variant for determining the matrix composition and is used unless otherwise specified in this text. XPS means X-ray photoelectron spectroscopy and is also called ESCA (Electron Spectroscopy for Chemical Analysis). Unless stated otherwise, the atomic percentages are in each case based on the total atomic numbers measurable by this method.

Part of the invention is also an electrical component with at least one point to be electrically contacted, with a plasma-polymer matrix being arranged around this point

(i) is an amorphous hydrocarbon (a-C: H) layer measured by XPS consisting of> 90 atomic% of elements C and O or

(ii) a C-containing SiO _x layer comprising 5 - 80 atom% C, preferably 8 - 60 atom% C, particularly preferably 10 - 40 atom% C, in each case based on the total number of all atoms of the plasma polymer Matrix without H, preferably measured at a distance of the average of the wire from the joint and wherein the matrix has a layer thickness of 5 -100 nm and wherein at the point to be electrically contacted, a wire is connected through the plasma polymer matrix.

It has surprisingly been found that it is quite possible to connect through the matrix a wire with the point to be contacted, preferably by welding, soldering, interfacial soldering, wire bonding or sintering. In this process, as already indicated above, the plasma-polymer matrix does not interfere, but rather seems to ensure that a particularly secure connection can be made. Since the wire has to penetrate the matrix for contacting the site to be contacted, of course, a corresponding plasma-polymer matrix is no longer arranged between the site to be contacted and the wire. However, a corresponding remainder of the plasma-polymer matrix remains around the wire, although the plasma-polymer matrix in the immediate vicinity of the wire may be changed in terms of its composition by the bonding process. Therefore, it is preferred according to the invention that, in the event that a wire is already connected to the site to be contacted, the respective composition information for the plasma polymer matrix measured at a distance from the wire equal to the diameter of the wire. In this range, the composition is regularly reliable composition, which also existed before the connection at the point that is now occupied by the wire. With regard to preferred embodiments of the plasma polymer matrix, the above explanations apply.

Of course, it is inventively preferred that even for an electrical component in which a corresponding compound is already made, the point to be contacted electrically consists of Cu or a Cu alloy. Also preferred according to the invention is an electrical component which comprises at the point to be contacted a wire made of Cu, Al, Au, an Al alloy, a Cu alloy or an Au alloy connected to the point to be electrically contacted.

Particular preference is given to an electrical component having at least one point to be electrically contacted, which consists of Cu or a Cu alloy, around which point a plasma-polymer matrix (as defined above) is arranged, copper nanoparticles being dispersed in the plasma-polymer matrix , and at the point to be electrically contacted, a wire of copper or a copper alloy is connected through the plasma polymer matrix. In addition, according to the invention, a component in which the connection between the wire and the point to be contacted in the wire shear test is carried out according to the German Association for Welding EV test method for wire bonds, leaflet DWS 281 1, August 1996, item 5, a proportion based on the bonding surface of> 50% shear fracture in the bond and <50% shear fracture in the bond / metallization interface, preferably> 75% shear fracture in the bond and <25% shear fracture in the bond / metallization interface. Depending on the layer design, at least 80% of the tested bond compounds should preferably have a maximum fraction of shear fracture in the bond / metallization interface of 50%. Further preferred here is an embodiment, so that up to 90% of the bonds have a maximum fraction of shear fracture in the bond / metallization interface of 25%. As metallization in the sense of DVS 281 1 here the metallic point to be contacted of the substrate is meant.

With the wire shear test (see DVS 281 1, point 5) it can be shown whether the actual connection point between the point to be contacted and the wire is the weakest link in the connection chain. In a shear fracture in the bond / metallization interface (adhesive failure), the compound is relatively unstable. If a shear failure occurs in the bond (cohesive failure), the bond between the wire and the site to be contacted is relatively stable. This is, of course, an advantage for the stabilization of the overall system, in particular in that the connection between wire and component (at least predominantly) does not weaken the overall stability.

Further preferred according to the invention is an electrical component, wherein the plasma polymer matrix measured with ERD comprises> 10, preferably> 20 atomic% H, based on the total number of all atoms C, O, Si and H. contained in the plasma polymer matrix Also called ERDA measurement (Elastic Recoil Detection Analysis) also detects the hydrogen atoms. In this case, it is preferred according to the invention for the hydrogen fractions determined by this measurement method to be> 25%, more preferably from 25 to 60% hydrogen, based on the total number of all C, O and H atoms contained in the plasma polymer matrix (measured by means of ERD) includes.

These hydrogen moieties, especially at the preferred concentration, in combination with the other constituents, especially the carbon atoms present in the preferred bonding ratios, contribute in a superior manner to a reducing performance of the matrix material. Preferred is an inventive electrical component, wherein the matrix material comprises

in case (i): (amorphous hydrocarbon layer)

O is 20-40 at.%, Preferably O is 25-35 at.% And

C is 50-75 at%, preferably 60-75 at% and preferably

N 0, 1 - 10 atomic%

or in case (ii): (carbon-containing SiOx layer)

Si is 10 to 40 atomic%, preferably 20 to 35 atomic% and

O at 20-55 at%, preferably 30-50 at.% And preferably

C at 5 to 55 atom%, more preferably 35 to 55 atom% and also preferably N 0, 1 to 8 atom%

in each case based on the total number of all atoms contained in the plasma polymer matrix without H and measured by means of XPS. According to the invention, it is further preferred that the ratio of Si: O is 0.4 to 1, preferably 0.6 to 0.9, and / or

the ratio Si: C 0, 1 to 4, preferably 1 to 3 and / or

the ratio O: C is 0.2 to 1 1, preferably 0.5 to 7. The determination of these matrix material components is carried out by means of XPS.

It is not difficult for a person skilled in the art to adjust the corresponding matrix compositions. There is a wealth of information available in the field of plasma polymer technology. For example, the H content can be controlled by parameters such as the plasma excitation energy, the monomer mixture or the gas volume flows,

the O content is controlled by, for example, addition of O ₂ in the ionization or carrier gas and

For example, the C content controls the ratio between O ₂ to monomer.

Part of the invention is a method for preparing an electrical component for a connection process, comprising the steps

a) providing an electrical component with at least one point to be electrically contacted,

b) optionally reduction of the site to be contacted by means of reducing plasma (preferably atmospheric pressure plasma, AD plasma)

c) depositing a matrix as defined above at this location.

In this context, AD plasma means atmospheric-pressure plasma, but of course a reduction by means of low-pressure piasmas is also conceivable, which then makes sense if the entire process is to take place under low-pressure conditions. However, it is preferred that the process according to the invention takes place at atmospheric pressure.

For the meaning of the term "connection process" we refer to the above explanations.

With regard to preferred embodiments of the plasma polymer matrix, the above explanations apply. By means of this method according to the invention it is possible to produce the electrical components according to the invention.

Part of the invention is also a method for connecting a wire to a position of an electrical component to be contacted electrically, comprising the steps:

a) providing an electrical component as described above prepared for electrical contacting as defined in any one of claims 1 to 3,

b) providing a wire,

c) contacting the coating over the point to be electrically contacted with the wire and

d) connecting the wire through the layer to the point to be electrically contacted.

In this way, the components according to the invention are produced, which have already connected a wire at the points to be contacted.

In the production of semiconductor chips in particular, there is a need to produce conductive connections at its contact surfaces. The conductive connections may be to other pads on the chip or to pads of peripheral devices, e.g. Housings, printed circuit boards, etc. lead. Thin wires made of gold, copper or aluminum alloys are used. The connecting of the thin wires takes place here by a process known as wire bonding. The wire is bonded (e.g., welded) to the pads by pressure, temperature, mechanical vibration, or a combination of these. Of particular importance here is the use of mechanical vibrations in the ultrasonic range, the ultrasonic bonding.

In ultrasonic bonding, a welding tool is used to make the conductive connection, which is designed as a capillary in ball bonding or wedge-shaped in wedge bonding. A wire guide guides the wire to be joined to the end of the welding tool so that the wire is positioned between the welding tool and the surface to be bonded (to be electrically contacted). The bonding tool is subjected to ultrasonic vibrations in such a way that the foot of the bonding tool oscillates in the plane of the contact surface (the point to be electrically contacted) of the semiconductor chip. Through these vibrations in conjunction with a force application of the bonding tool in the direction of the contact surface the wire is welded with its end on the contact surface and thus the conductive connection is made on the contact surface of the semiconductor chip.

After the connection of the wire has taken place on the first contact surface, the bonding tool travels after possible mechanical separation of the bonding wire to the next contact surface to continue the process of establishing the conductive connection.

It is therefore preferred in this context that step d) takes place for connecting the wire by means of ultrasound support and / or by means of thermal welding.

For connecting a copper component coated with a metallic polymer nanoparticles dispersed in a plasma polymer matrix with another component, the two components are brought into contact with one another, preferably at a pressure of 2.5 kPa to 1000 kPa, particularly preferably 10 kPa to 250 kPa, based on the surface to be contacted acted upon and heated under inert gas to a maximum of 400 ° C, preferably to a maximum of 300 ° C, more preferably to a maximum of 250 ° C. It is further preferred that the deposition in step c) of the method for preparing the electrical component by a CVD method, in particular by a PE-CVD method. Most preferably, this process is carried out at atmospheric pressure.

In this way, by means of one or more of the aforementioned measures can be effectively electrical components for contacting, i. Prepare for a connection process or establish stable electrical contacts at the appropriate locations for the components of the invention.

Preference is given to an inventive method for preparing an electrical component for a bonding process, wherein in step c) a hydrocarbon and / or an organosilicon compound is used as a precursor, preferably a hydrocarbon selected from the group consisting of ethyne, ethene, propyne, propene, cycloalkanes , Cycloalkenes and alcohols having a number of C atoms <= 10, preferably butanol, pentanol and cyclopentanol and / or preferably an organosilicon compound having a number of Si atoms <= 5, preferably selected from the group consisting of HMDSO, TEOS, TMS, HMDSN, octamethylcyclotetrasiloxane. Further preferred in this method is that a nozzle is used in step c), which comprises a relaxation space downstream of the electrodes.

By means of the abovementioned measures, the components according to the invention prepared for contacting (connection process) with a wire can be produced in a particularly effective, resource-saving and quick and reliable manner.

The CVD methods are familiar to the person skilled in the art, he masters the corresponding technologies and they make it possible to make the appropriate preparations for the site to be electrically contacted with sufficient location accuracy and in a reasonable cost-benefit ratio. For reasons of manageability, an atmospheric pressure method is preferable to a low pressure method.

In the preferably used nozzle with relaxation space this serves to ensure that the matrix materials can give off part of their thermal / kinetic energy before contact with the target surface, then the deposition takes place under less rigid conditions. Also, the energy transfer from the plasma to the monomer can be better controlled.

The articles produced by the method according to the invention or the articles according to the invention have the advantage that they are not only effectively producible, but also support the bonding process, in particular to wires, very particularly to thin wires in an outstanding manner:

Without wishing to be bound by theory, it is believed that the matrix is particularly effective in allowing reliable bonding between the contacting site and metal wire because it effectively prevents the formation of metal oxides at the site to be contacted. At the same time, it can act as a flux and / or reduce it. The main effect, however, is likely to be the already described passivation: Where the matrix is located, the direct access of oxygen is at least impeded, so that an oxidation of the metals present at the point to be contacted (preferably Cu) is not carried out or is made much more difficult.

Reference has already been made above to the published patent application DE 10 2009 048 397 A1. For the preferred embodiments of the process of the invention, the PE-CVD PVD nozzle geometry disclosed in this document is particularly preferred. Accordingly, the nozzle arrangements depicted in FIGS. 1 to 3 of DE 10 2009 048 397 A1, together with the associated descriptions (paragraphs [0060], [0070]), are part of this description by way of reference.

A suitable (and preferred) method and apparatus for making a plasma polymer coating (i.e., a plasma polymer matrix within the meaning of the present application) having dispersed therein particles using an atmospheric pressure plasma is disclosed in DE 10 2009 048 397 A1. The plasma is generated by a discharge between electrodes in a process gas. At least one of the electrodes is a sputtering electrode from which sputtering nano-particles (as defined above) are sputtered, and these nano-particles are subsequently deposited on a substrate together with coating precursor compounds (precursors). Thus, a coating is formed with particles dispersed therein. The deposition preferably takes place in the absence of oxygen in order to prevent oxidation of the metallic nanoparticles

Another method for the production of nanoparticles and a corresponding device are described in the German patent application with the application number DE 10 2013 017 109.1. According to this method, nanoparticles are produced using an atmospheric pressure plasma, wherein the plasma is generated by a discharge between electrodes in a process gas,

at least one of the electrodes is a sacrificial electrode from which material is removed by the discharge,

the abraded material is nanoparticles and / or nanoparticles are formed from the abraded material, and

a portion of the sacrificial electrode is actively cooled so that the average temperature of the sacrificial electrode in a region of the sacrificial electrode outside the discharge area of the sacrificial electrode is lower than within the discharge area of the sacrificial electrode.

With the method and the device of og. In the case of a non-prepublished German patent application, nanoparticles may also be incorporated into a plasma polymer layer (i.e., a plasma polymer matrix within the meaning of the present application).

Preferred is an apparatus for producing particles in an atmospheric pressure plasma according to the third embodiment of the above not 3, it is particularly preferred that this device is modified in such a way that a relaxation space is provided after the cooled sacrificial electrode (target). This relaxation space is preferably 5 to 100 mm, particularly preferably 20 nm to 50 mm long. By providing the relaxation space, it is achieved that the yield of nanoparticles increases and, on the other hand, the resulting nanoparticles are provided with an aC: H layer formed from the excited plasma polymer precursor (eg cyclopentanol) during their residence time in the relaxation space. The feed location of the plasma polymer precursor is preferably provided at the level of the sacrificial electrode or likewise preferably downstream of the sacrificial electrode.

By means of the method according to the invention, but in particular using a preferred nozzle geometry, a high-quality matrix can be deposited. In this context, high-quality means, in particular, that there are only a few defects. This number of defects can be checked by means of the silver nitrate drop test (see Example 2). Accordingly, it is preferred according to the invention that a matrix to be used according to the invention in the silver nitrate drop test (compare Example 2) has <15, preferably <10, more preferably <8 and very preferably <5 defects / 25 mm ² .

The invention will be further elucidated by way of examples: Examples

1. Wire shear test

The Wire Shear Test is performed in accordance with DVS 281 1, item 5 (Test Methods for Wire Bonding, dated August 1996).

Here, the shearing bit is aligned parallel to the (originally) to be contacted site. Subsequently, the bit is brought into the so-called touchdown position, which means that contact exists with the substrate on which the (originally) to be contacted point lies. Thereafter, the shear chisel is brought to the shear height (shear height: half wire thickness, if a bonding ball was used: half bondball thickness). Then a shearing force is exerted on the bonded wire at the shear height via the shear chisel and this force is increased until shearing occurs. This force is measured. During shearing, the shearing characteristics described in DVS 281 1, section 5 can occur. The higher the value of the bond, the less likely a shear failure will occur in the bond / metallization interface. The results are based on a statistical evaluation of the wire shear tests for at least 30 bonds on the treated substrates, as well as a surface analysis of the fractions of the different shear fractions of each individual bond.

2. Silver Nitrate Drop Test

An AgNO ₃ solution having a concentration of 0.01% by weight of silver nitrate is prepared. The right concentration ensures the formation of individually differentiable Ag crystals that can be counted, and at the same time that the solution contains enough silver ions to deposit at any defect sites without the solution being depleted by too large (rapidly growing) defects.

Vers u c tio ns:

1. The test solution is applied to the test (coated) site by means of a pipette. For examining flat surfaces, for example, 200 μΙ makes sense.

2. Leave the solution on the sample for one hour avoiding direct sunlight. It must be ensured that there is no significant evaporation of the silver nitrate solution. Here it makes sense to cover the test site with a small-volume cover.

3. Following is an evaluation of the test result using a microscope image. Sensible magnification factors are 20 to 30 times. It is microscopically examined through the drop and the visible silver particles are counted.

Comments on the test procedure:

Care must be taken to ensure that the samples are stored vibration-free and vibration-free during the test period.

A reaction of the test solution with the layer to be tested must be avoided.

If necessary, the layer must be in a hydrophobic state before measurement by heat treatment (static water edge angle> 90 ° measured according to DIN 55660 - 2: 201 1 - 12). be transferred. A reduction in volume of the drop of the test solution is to be avoided as far as possible by suitable measures.

For comparability, the test duration must be kept clean. Assessment: - Good result: Defect densities in the range <10 defects / 25 mm ² .

"Average result": defect densities in the range of 1 to 30 defects / 25 mm ^2. Poor result: defect densities in the range of> 30 defects / 25 mm ² .

3. Preparation of an Example of an Electrical Component for a Bonding Process The plasma polymer layer was deposited on a Cu-coated silicon wafer using the atmospheric pressure (AD) plasma system OpenairPlas from Plasmatreat.

The nozzle developed by IFAM was used acc. DE10 2006 038 780 A1 (in particular FIG. 1 and associated text parts such as paragraphs 0035 - 0040). For pre-treatment of the surface, the AD plasma system was used. In this case, a nitrogen plasma was generated in the nozzle and out through the nozzle exit from the nozzle. The reducing effect of the plasma is produced by the addition of hydrogen (<5 vol.%) In the nozzle head. Alternatively, N ₂ / H ₂ mixtures with up to 5% H ₂ content as ionization gas are also possible here. The nozzle was then passed over the surface to be coated at a constant speed, eg 10-50 m / min (here 25 m / min). (Gas flows: 25-35 l / min, N ₂ , here: 29 l / min N ₂ , 1- 3l / min H ₂ , here 2 l / min) In the direct connection to this treatment, the layer deposition takes place - possibly in one Atmosphere under exclusion of oxygen. a.) To form the layer of an aC: H layer, the plasma was generated in the nozzle with the ionization gas nitrogen (29 L / min). The plasma was thereby generated by arc-like discharges applying a pulsed high voltage with the frequency between 17 and 25 kHz, with a combination of FG 5005 (generator) and HTR 1 1 (transformer) in a range of 300-400V and 100% PCT , The "basic nozzle (nozzle body)" has the designation PFW 10. The precursor mixture is ejected into the plasma thus produced at the nozzle exit vaporized monomer (eg cyclic carbon compounds, here cyclopentanol etc. at 150 ° C, 6g / h monomer) and the carrier gas nitrogen (2 l / min) fed.

Again the nozzle was then rinsed at speeds between e.g. 5 and 50 m / min (here 25m / min) over the surface to be coated at a distance of 3 mm (in the case of an oxygen-containing atmosphere) out. The distances can in principle be increased or reduced in favor of or at the expense of the layer deposition rate. The same applies to the speeds of movement of the nozzle or the component under the nozzle. Layer deposition using compressed air plasma is also possible - compared to nitrogen plasmas but with a reduced deposition rate.

In the case of organosilicon coatings, the same details apply to the equipment and settings as above (Example 3a), unless otherwise stated.

To form combination layers of organosilicon (organosilicon in these experiments hexamethyldisiloxane (HMDSO), otherwise also TEOS, etc.möglich)) and organic monomers (eg cyclopentanol, etc.), both monomers are evaporated (here 30 g / h HMDSO at 100 ° C and 15 g / h cyclopentanol at 150 ° C), mixed with a carrier gas stream of 2 L / min N ₂ and then fed into a compressed air plasma (300-400V, 19 kHz, 100% PCT) with 29 L / min compressed air.

Again, the nozzle was then scanned at speeds between e.g. 5 and 100 m / min over the surface to be coated at a distance of 6 mm (oxygen-containing atmosphere) out. The distances can in principle be increased or reduced in favor of or at the expense of the layer deposition rate. The same applies to the speeds of movement of the nozzle or the component under the nozzle.

To form a layer of an aC: H layer with embedded copper nanoparticles, the plasma was generated in the nozzle with the ionization gas nitrogen (29 L / min). The plasma was thereby generated by arc-like discharges applying a pulsed high voltage with the frequency between 17 and 25 kHz, with a combination of FG 5005 (generator) and HTR 1 1 (transformer) in a range of 300-400V and 100% PCT , The "basic nozzle (Nozzle body) "has the designation PFW 10. In the plasma thus produced, the precursor mixture of vaporized monomer (eg cyclic carbon compounds, here cyclopentanol etc. at 150 ° C, 6g / h monomer) and the carrier gas nitrogen (2 l / The production of the copper nanoparticles was effected by removal from a sacrificial electrode in accordance with the above-mentioned unpublished German patent application A modified embodiment of the device according to FIG. 3 of the above-unpublished German patent application was used, according to the cooled sacrificial electrode (target). A relaxation space of 50 mm in length is arranged The feed location of the precursor mixture was 10 mm downstream of the sacrificial electrode.

The resulting layer thickness was in all cases about 100 nm. Smaller layer thicknesses <50 nm, preferably <30 nm are possible in general and not only in this special coating method. A greater layer thickness can be achieved by repeating the coating process directly after the first process.

Connection of wires to points to be contacted

The substrates, so-called DCB ^'s (Direct Copper Bonding) substrates, were first coated analogously to Examples 3a and 3b and then placed and fixed in the Drahtbondmaschine. A DCB is a ceramic substrate that has been coated with a layer of copper (metallization).

The wire bonding process was carried out in accordance with DVS 2810 (Wire Bonding, September 1992). The bonding of the coated DCB ^'s was carried out with a Delvotec G5 6600 using a 300 μηη Al-H1 1 bonding wire (here according to wire bonding, point 2.3.2, the DWS 2810 with ultrasonic heat welding according to point 2.1.3). The set bonding force was between 50 and 2000 cN. The bond head moves to the point to be bonded (bond pad 1) and contacts there the bonding wire with the substrate. The bonding head then moves to the bondpad 2 - tracking the bonding wire - and carries out the same bonding process as on the bonding pad 1. Following the bonding process on the bonding pad 2, the bonding wire is severed mechanically and the process can begin again at a new location on the substrate , A copper component coated according to example 3c) is brought into contact with a further copper component, subjected to a pressure of 25 kPa relative to the surface to be contacted and heated to 250 ° C. under protective gas. As the check by means of a continuity tester shows after cooling, a continuous metal phase has formed between the surface of the coated component to be contacted and the further copper component.

Test Results: The according to Example 3a and 3b prepared DCB ^'s, with the fact in accordance with Example 4 bonded wires were subjected to the test procedure of Example 1 and 2. FIG. The results are as follows: C: H prepared ^DCB's (Example 3a, after conversion to hydrophobic state)

AgN0 ₃ test: <25 defects / 25mm ²

Scher test: 70% of the cases with an area fraction of 50-75% of the bonding surface as a shearing (cohesive failure)

Silicon Organics + aC: H prepared DCB ^'s

AgN0 ₃ test: <20 defects / 25mm ²

Shear test: 90% of cases with more than 75% of bond area as a breach (cohesive failure)

Cu nanoparticles + aC: H prepared DCB ^'s from Example 4b

Scher test: 75% of the cases with 50-75% of the bond area as a breakthrough (cohesive failure)

Claims

claims:

1. Electrical component with at least one electrically contacted point, wherein at this point a plasma polymer matrix is arranged, the

(ii) a C-containing SiO _x layer comprising 5-80 atomic% C, based in each case on the total number of all the atoms of the plasma polymer matrix without H, and wherein the matrix has a layer thickness of 5-100 nm.

2. Electrical component according to claim 1, wherein the point to be electrically contacted consists of Cu or a Cu alloy.

3. Electrical component according to one of the preceding claims, wherein the plasma polymer matrix exerts a passivating effect on the oxide layers of the site to be contacted.

4. Electrical component, with at least one point to be electrically contacted, wherein around this point around a plasma-polymer matrix is arranged, the

(ii) a C-containing SiCy layer comprising 5-80 atom% C, in each case based on the total number of all the atoms of the plasma polymer matrix without H, preferably measured at a distance of the average of the wire from the

Junction and

wherein the matrix has a layer thickness of 5 -100 nm and

wherein at the point to be electrically contacted, a wire is connected through the plasma polymer matrix.

5. Electrical component according to claim 4, wherein the point to be electrically contacted consists of Cu or a Cu alloy.

6. An electrical component according to claim 4 or 5, wherein the wire consists of Cu, Al, Au an Al alloy, a Cu alloy or an Au alloy.

7. Electrical component according to one of claims 4 to 6, wherein the connection between the wire and the point to be contacted in the wire shear test a Area fraction based on the bond area of the intersection of> 50%, preferably> 75%.

8. Electrical component according to one of the preceding claims, wherein the plasma polymer matrix measured with ERD to> 10, preferably> 20 atom% comprises H, based on the total number of all contained in the plasma polymer matrix atoms C, O, Si and H.

9. The electrical component according to one of the preceding claims, wherein the matrix material comprises:

in case (i):

O to 20-40 atom%, and

C to 50-75 atom%,

or in case (ii):

Si to 10 - 40 atom% and

O to 20-55 atom%

in each case based on the total number of all atoms contained in the plasma polymer matrix without H and measured by means of XPS.

10. Electrical component according to one of the preceding claims, wherein metallic nanoparticles are dispersed in the plasma polymer matrix.

1 1. A method of preparing an electrical component for a bonding process, comprising the steps of:

b) optionally reduction of the site to be contacted by means of reducing plasma and

c) depositing a matrix as defined in any of claims 1, 4, 9 and 10 defined at that location.

12. A method for connecting a wire to an electrically contacted point of an electrical component, comprising the steps:

a) providing an electrical component having at least one electrically contact point as defined in any one of claims 1 to 3, b) providing a wire, c) contacting the coating over the point to be electrically contacted with the wire and

13. The method according to claim 12, wherein step d) takes place with ultrasound assistance and / or or by means of thermal welding.

14. The method of claim 1 1, wherein step c) is carried out by a CVD method, in particular by a PE-CVD method.

15. The method according to any one of claims 1 1 or 14, wherein step c) is carried out at atmospheric pressure.

16. The method according to any one of claims 1 1 or 14 to 15, wherein in step c) a hydrocarbon and / or an organosilicon compound is used as a precursor, preferably a hydrocarbon selected from the group consisting of ethyne, ethene, propyne, propene, cycloalkanes , Cycloalkenes and alcohols having a number of C atoms <= 10, preferably butanol, pentanol and cyclopentanol and / or preferably an organosilicon compound having a number of Si atoms <= 5, preferably selected from the group consisting of HMDSO, TEOS, TMS, HMDSN, octamethylcyclotetrasiloxane.

17. The method according to any one of claims 1 1 or 12 to 16, wherein a nozzle is used in step c), which comprises a relaxation space downstream of the electrodes.

Use of a matrix as defined in any one of claims 1, 4, 9 to 10 for preparing a site to be electrically contacted for connection to a wire.