COMPONENT OF CONNECTION PROVIDED With INSERTS WITH COMPENSATION HOLDS.

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The art to which the invention is that of microelectronics, and more specifically that of the manufacture of nano-structures microet.

The invention relates to all manner of devices having tips or inserts, for example their interconnection with other electronic components in steps reduced.

More specifically, the present invention provides a particular insert, as well as materials suitable for the production thereof.

In the connectics using the technique known as" flip chip "" Or "flip chip", the current trend is to the reduction of the "not", i.e. the distance between the interconnects connecting chip and substrate.

In such a technique, a substrate carrying all of the contacts, in the form of raised parts or metal protrusions called" bumps " Which are located on a single side. The chip is turned upside down so that the protrusions can be welded to the appropriate conductors, positioned on the chip. However, the conventional hybridization assays, such the solder of protrusions, the thermocompression Bollards, the ACF (" Conductive Anisotropic Films ") Or the use of conductive polymers show their boundaries, in terms of reducing the pitch.

The document W02006/054005 provides interconnection by inserting a conductive tip hard ductile box. The device, illustrated in Figure 1, allows for a decoupling of the mechanical holding and the electrical interconnection. For this purpose, the electrical interconnection is performed by inserting a tip 1, made of a hard material, buried in a casing 2, made of a ductile material.

This document proposes two different ways to ensure mechanical retention of this structure: by molecular adhesion between the protrusions or by a layer of adhesive.

Or, the molecular adhesion between the protrusions is technologically difficult to achieve, because it is necessary to flatness of the surfaces to be bonded. Indeed, the substrate 3 and the chip 4, which may be made of different materials in the case of heterogeneous integration, are to be planar and have, as additional constraint, of different materials at the interface. By way of example and in relation to this document, the material constituting the substrate 3 is different from the material constituting the ductile box 2. Furthermore, the temperature of molecular adhesion is generally high and incompatible integration of structures having different coefficients of thermal expansion.

The other alternative, i.e. adhesion by an adhesive layer, is also difficult to achieve, due to the inability of the integrating upon hybridization. Indeed, there is no space between the chip and the substrate 4 3 for allowing the glue to propagate. Furthermore, the solution of the adhesive prior to hybridization is not possible because the same would be pushed out from the interface because of the pressure exerted.

Furthermore, such a device has no ability to accommodate departures from parallelism during hybridization and defects topology" wafer ". Indeed and as shown in Figure 2, these defects create local heavy pressures, permanently damaging the component. In the case of unevenness, non-contact areas may also be created.

The proposed invention is in the search for a technical solution for, simultaneously with the electrical connection, provide the mechanical holding and topology compensate for defects due to hybridization step or" wafer " Itself.

Thus and according to a first aspect, the invention relates to a component comprising, on one side, a set of conducting inserts to be electrically connected with conductive buried areas of another component.

The invention, the inserts rest on conductive slot wedges positioned to the surface of the component.

According to the invention, the components are advantageously a chip and a substrate, to be connected electrically and mechanically.

Although It has been described of connecting such components by means of inserts, preferably micro-inserts or microtips, introduced into buried ductile protuberances, seen by the second component to be joined.

According to the invention, the connection device comprises an additional element, in other words a wedge, also called base or on, disposed to the surface of the component, in particular the chip, and on which the insert rests.

The wedge has the feature essential to be conductive. This means that it is made of a conductive material, hereinafter termed a M5, or in an insulating material, such as a polymer, coated with a conductive layer.

Such shim is also defined by its height h '.

Advantageously, it has a surface area larger than that of the bearing surface of the insert on the wedge.

Advantageously, wedge conductive, at its contact surface with the insert, at least one dimension greater than that of the area opposite of the insert that it carries. Therefore, the depth of the depression of the insert in the said protuberance is controlled by this wedge which abuts, at least locally, at the surface of the other component. The wedge stop height h ', it is possible to provide a space between the two components, in particular for introducing an adhesive layer.

According to a preferred characteristic, the wedge is made from a material deformable (M5).

In this regard and preferably, the material (M5) conductive of the wedge has a ductility higher than that of the material component (ml) 1' insert, or that of the material constituting the zone (M2) for receiving the insert.

To fill the latter condition and example, 1' insert is made from gold (At) and the wedge is made of aluminum (Al) or indium (in), or it is made of polymer coated with a film of At.

As already said, such a structure can compensate for flatness defects, either related to the machine (Figure 3), or the wafer (Figure 4), frequently encountered in the interconnect thematic" flip-chip " Large area. Indeed and by the deformable nature of the material thereof, the height h ' of the wedge is likely to vary locally, thereby lowering when the stresses cause its compression.

According to the invention, it is possible the dimensioning wedge, according to the topology of the components to be connected.

Therefore, the variation of maximum height, noted Ah, between each end of an interconnection array whose elements are separated by a distance d, to compensate for during hybridization, is given by the following formula:

Ah = Tan (Has) .c/

wherein a represents the non-parallelism (Figure 3).

For a lack of parallelism has given, the level variation Ah creating stresses at a distance d equal to 2 cm is tabulated in the table below:

In the frame of the present invention and preferably, the height h ' of the wedge is dimensioned such that the plastic or elastic deformation of the component material M5 compensates for a defect of the flatness, embodied by the magnitude Ah.

Therefore, if a distortion less than Y % of the height of the wedge h 'is searched, the thickness thereof (h'), in the case of a lack of parallelism, is given by the following formula:

tan (a ), d

7/100

In the case of a fault related to the flatness of the wafer Ah (Figure 4), the height h ' of the wedge, expressed as a function of the intended deformation of Y %, is given by the formula:

Κ ≥-M

100

In a second aspect, the present invention also provides a method of connection between two components, in particular a chip and a substrate, the first component being provided with inserts based on a wedge, as described further below, and the second component being provided with ductile buried conductive areas positioned opposite these inserts.

Therefore, introducing the inserts in these areas, until the wedge inserts abuts, at least locally, to the surface of these areas that also corresponds to the surface of the second component.

Due to the deformable wedge, it is possible to connect parallel the two components, even in the case of a lack of parallelism in hybridization or a non-constant thickness of the "wafer".

As already said, mechanical retention of that connection may be made by means of glue introduced into the space provided by the shims inserts, at the interface of the two components.

Sizing of the wedge is also provided for predicting the volume of the adhesive to be charged for a good maintenance:

Vcolle = 1, / * (d² L-L*)* h '* N

wherein

-d is the repetitive pitch between two elementary patterns;

N-denotes the number of interconnecting elements (= insert element + wedge);

h-' is the height of the wedge;

-L designates the width of the wedge;

And 1-denotes the length of the wedge.

In the formula, the factor 1.1 to overrate 10% of the minimum volume to be deposited to obtain a homogeneous bonding on the entire chip.

The dispensing adhesive can be performed by a local depot to the central point of the chip or by centrifugation to deposit a controlled height.

Therefore, the present invention overcomes the deficiencies of the prior art, in other words the irreversible damage to the interconnection and component itself if the insert is not positioned above a deformable material, said deterioration is caused by very large local stresses related to the defects of parallelism in the inserting step (cf. Figure 2) or flatness deviations.

As already said, the present invention has a wide range of applications, especially for the interconnection of type" flip chip " Of heterogeneous materials, for example for infrared imagers large.

The manner in which the invention can be realized and the accompanying advantages shall become apparent better still from the example embodiment which follows, given as indicative and non-limiting, the basis of the appended Figures of which:

Figure 1 illustrates a substrate/chip connection system according to the prior art.

Figure 2 illustrates the stress of a device according to the prior art, in the case of a lack of parallelism.

Figure 3 portrays the structure according to the invention for retrofitting departures from parallelism to long distance.

Figure 4 portrays the structure according to the invention for retrofitting for flatness defects related to the topology of the wafer.

Figure 5 portrays the method of manufacturing a device according to the invention.

Figure 6 illustrates the deformation of the structure according to the invention taking up departures from parallelism and for the integration of an adhesive film.

Figure 7 illustrates the deformation of the structure according to the invention which compensate for flatness defects related to the wafer and for the integration of an adhesive film.

An interconnection device according to the invention can be implemented in the following manner, as illustrated in Figure 5:

-multi-layer coating materials (M5 and ml, respectively) constituting the step 5 and the tip 1 on the chip 4 or the substrate 3 (Figure 5A);

-depositing resin/photo/etching the material layer ml (Figure 5B);

-depositing resin/photo/etching the material layer M5 (Figure 5C);

-depositing a resin "planarizing" 6 (Figure 5D);

-step of printing the resin by a mold and curing the resin temperature (Figure 5th), or UV;

-replication of the shape of the resin by ion milling or RIE plasma (Figure 5F).

US 2005/191842 The document describes the production of a polyimide, on which it is contemplated that inserts perform as described above.

Insertion of the tip 1, mounted on a deformable shim 5, ductile in the box 2 of the corresponding element (chip 4 or substrate 3) and maintaining the interconnection by means of adhesive 7 illustrated in Figures 6 and 7, in the case of defects parallelism and flatness defects related to the wafer, respectively.

From clearly of the present application that an assembly according to the present invention has many advantages by allowing:

-controlling the blocking of insertion z by walking or stopper wedge below 1' insert;

increased tolerance on the insertion pressure due to the deformation of the wedge driving the homogenization of the pressure on the component;

compensate for defects of flatness of the surfaces by the deformation of the wedge;

manage the excess material discharged upon insertion to avoid creating short by the cavity between the tips;

control the thickness between the chip and the substrate by the thickness of the step, thereby allowing the integration of an adhesive film uniform.