Method for manufacturing a microelectronic device and a microelectronic device thus manufactured

The invention pertains to a method for manufacturing a microelectronic device on a substrate comprising at least one first electrical component and one second electrical component distributed respectively in first and second levels stacked one on top of the other on the substrate, this method comprising:

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the Apr. 26, 2010 priority date of French Application No. 1053156, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The invention pertains to a method for manufacturing a microelectronic device on a substrate and to the manufactured microelectronic device.

A microelectronic device is a device manufactured by a collective microelectronic manufacturing method. Thus, typically, a microelectronic device is manufactured by the stacking and etching of successive layers, for example by means of photo-lithography.

Microelectronic devices comprise at least one first electrical component and one second electrical component distributed respectively in first and second levels stacked one on top of the other on the substrate.

An electrical component is any component that needs to be electrically connected to another electrical component made on the same substrate in another level. For example, the electrical component is a microelectronic chip, a conductive track or an electrical interconnection.

The term “microelectronic chip” herein designates a piece of a semiconductive wafer. Preferably, this piece of wafer has one or more electronic components such as transistors, capacitors, resistors inductors, MOS (Metal Oxide Semiconductor) components, MEMS (microelectromechanical Systems) or NEMS (nanoelectromechanical systems) or the like. These components are etched or deposited on this piece of wafer by collective microelectronic manufacturing methods such as lithography, DRIE (Deep Reactive Ion Etching) or the like.

PRIOR ART

Prior art methods for manufacturing a microelectronic device of this kind comprise:

the manufacturing of at least one electrical pad whose width and length are greater than its thickness, this pad having an upper face, and then

the electrical connection of the second electrical component to said upper face to electrically connect this electrical component to the first electrical component by means of this pad.

For example, the patent application WO 2009/147 148 discloses a method for the manufacturing of a microelectronic device wherein an electrolytic interconnection, called a “second type” interconnection, passes right through a lateral encapsulating layer of a microelectronic chip in the first layer. This interconnection is made out of copper and has a substantial cross-section, i.e. a cross-section greater than 10 μm2, to have a plain upper face that is wide enough to reliably set up electrical contact with the upper layer. Because of the substantial cross-section, when the microelectronic device is subjected to an increase in temperature, the pad expands greatly. This expansion can damage the microelectronic device.

Thus, there are two conflicting technical constraints:

1. The cross-section of the interconnection must be large in order to have a large upper face in order to accurately set up electrical contact with the upper layer, and

2. At the same time, the cross-section of the electrical interconnection must be small enough to restrict the problems related to expansion or to increase the density of the interconnections.

Furthermore, the cross-section cannot be made smaller than is permitted by the prior art in lithography and electrolysis. There is therefore a boundary value for the ratio between the height and the width of this interconnection. Finally, the manufacture of the electrical pad calls for a large number of steps, including especially the performance of electrolysis. This method is therefore fairly complex and lengthy, and hence costly.

SUMMARY OF THE INVENTION

The invention is aimed at resolving at least one of these drawbacks by proposing another mode of manufacture of these microelectronic devices.

An object of the invention therefore is a method of manufacture wherein:

the method also comprises the manufacture of at least one first arm and one second arm of different lengths, each of these arms directly and mechanically linking the electrical pad to a respective fixed anchoring point on the substrate, and

the electrical pad is made inside the first level and then shifted, prior to the electrical connection of the second component, to a position of connection wherein the upper face of the electrical pad is in contact with the interior of the second level parallel to the substrate.

Here below in this description, the upper face is assumed to be inside a level even when it is simply flush with this level.

The above method has many advantages. The shifting of the electrical pad from its position of manufacture to the connection position enables the simple manufacture of a pad having an upper face greater than 10 μm2without its being thereby connected to the lower level by a pillar having a large cross-section. The problems related to the expansion of the electrical pads are therefore restricted. At the same time, the possibility of setting up efficient electrical contact with the microelectronic chip of a higher level is preserved. For example, it remains possible to implant micro-inserts on the electrical pad and deposit a meltable ball thereon to set up the electrical contact with the second chip. A micro-insert is a deposit of material used to set up electrical contact by thermocompression. For example the material is nickel. This is a special advantage of this method relatively to the other methods where the electrical contact is provided by the tip of a leaf spring that gets supported on a flat surface.

This method of manufacture is a collective method of manufacture for simultaneously manufacturing a multitude of identical microelectronic devices on a same substrate. The implementation of this method of manufacture requires fewer steps than existing methods. For example, the conductive tracks within the first level and the electrical pad can be made during a same step. Nor is there a step of electrolysis in principle.

Finally, the use of at least two arms of different lengths enables the precise setting of the maximum height to which the electrical pad rises above the substrate in the connection position.

The embodiments of this method may have one or more of the following characteristics:

the method also comprises the manufacture of at least one third arm mechanically connecting the electrical pad to another fixed anchoring point on the substrate, the end of this third arm being attached to the electrical pad at a point of attachment spaced from the points of attachment of the first and second arms, the length of this third arm being chosen to keep the upper face of the electrical pad parallel to the substrate in the connection position;

the method comprises the manufacture of four arms of same length, each mechanically and directly connecting a respective point of attachment of the upper face to a respective fixed anchoring point on the substrate, and at least one arm of a different length mechanically and directly connecting the electrical pad to a respective anchoring point on the substrate;

the shifting of the electrical pad is actuated by means of a temperature variation and/or an external supply of electrical or magnetic energy;

the method comprises, after the steps of manufacturing and shifting the electrical pad, the cutting of the substrate to separate the manufactured electronic device from the other microelectronic devices manufactured at the same time on the same substrate;

the method comprises, before the stacking of the second level and after the shifting of the pad, a step for encapsulating the first level with an encapsulating material to form a base on which the second level is then slacked and to immobilize the electrical pad in its connection position;

the method comprises, after the shifting of the pad and after the stacking of the second level, a step for encapsulating the microelectronic device with an encapsulating material to immobilize the electrical pad in its connection position;

after the shifting of the pad, the method comprises the stacking of the second electrical component at least partly above the electrical pad so as to connect the electrical pad to an electrical contact made so as to be facing an external face of the second electrical component;

the manufacturing of the electrical pad is done at the same time as the manufacturing of the conductive tracks and/or the conductive pads of the first level on the substrate;

the first and/or second electrical components are microelectronic chips.

These embodiments of the method furthermore have the following advantages:

using at least one third arm makes it possible to adjust the flatness and the parallelism of the electrical pad in the connection position;

using at least five arms makes it possible to position the electrical pad at the desired height while at the same time keeping it parallel to the substrate;

using an external supply of energy or a temperature variation makes it possible to activate the shifting of the electrical pad at the desired time;

the cutting-out step enables the collective manufacture of several microelectronic devices on a same substrate;

the encapsulating of the first level before the stacking of the second level enables the constitution of a rigid base on which the second electronic component can be easily and precisely positioned without hollows or guiding pivots being provided between the first and second levels;

the encapsulating of several levels at the same time enables a gain in time and simplifies the method;

the stacking of the second electrical component above the electrical pad limits the number of conductive tracks to be etched in the second level;

the manufacture of the electrical pad at the same time as the manufacture of the conductive tracks of the first level simplifies the manufacturing method.

An object of the invention is also a microelectronic device comprising:

a substrate,

at least one first and one second electrical component distributed respectively in first and second levels stacked one on top of the other on the substrate,

at least one electrical pad, whose width and length are greater than its thickness, by means of which said first and second electrical components are electrically connected to each other, this electrical pad having an upper face,

at least one first arm and one second arm of different lengths, each of these arms mechanically and directly connecting the electrical pad to a respective fixed anchoring point on the substrate.

The embodiments of this device may comprise the following characteristic:

the microelectronic device has a deposit of meltable or thermocompressible material to set up the electrical connection between the second electrical component and the pad.

In these figures, the same references are used to designate the same elements.

MORE DETAILED DESCRIPTION

Here below in this description, the characteristics and functions well known to those skilled in the art are not described in detail.

FIG. 1shows a microelectronic device2. This device2has a substrate4on which several electrical components are stacked. Here, the device2is described in the particular case in which these electrical components are microelectronic chips. Typically, the greatest dimension of a microelectronic chip is smaller than 5 mm.

The substrate4is a portion of a semiconductive wafer obtained after cutting-out step. This substrate is a plane substrate herein shown in a horizontal position. The horizontal position is identified by two orthogonal directions X and Y of which only the direction X can be seen inFIG. 1. In this figure, and in the following figures, the direction Z represents the vertical direction.

The substrate4has a plane upper face6on which conductive tracks are deposited or etched to connect the microelectronic chips to one another and to the different electronic components deposited on or integrated into the substrate4. The conductive tracks extend only within a same level. Typically, tracks for supplying power to the different superimposed microelectronic chips are made on the upper face6.

For the sake of simplification,FIG. 1shows only two microelectronic chips8and10apportioned respectively to the levels12and14. The level14is stacked on the level12. Each level has a constant thickness and extends in parallel to the face6.

These chips8and10have electrical contacts on their lower faces pointed towards the face6. For example, the chips8and10respectively have electrical contacts16,17and18,19. The contacts16and17are connected to conductive tracks22and24respectively, deposited or etched on the face6. For example, the electrical connection of the contacts16and17on the tracks22and24is made by means of micro-inserts or meltable balls.

Each track8,10is buried in its own encapsulating layer respectively,26and28. These encapsulating layers extend laterally on the entire periphery of each of the chips. These encapsulating layers are used to protect and fix the chips on the substrate definitively. For example, they are made out of polymer such as an epoxy type resin. Here, the demarcation between the encapsulating layers26and28corresponds to the boundary between the levels12and14.

The device2also has electrical interconnections to electrically connect the chips8and10to each other. Here, two interconnections32and34are shown. For example, each of these interconnections32,34electrically connects the chip10to conductive tracks of the substrate electrically connected to the chip8.

These interconnections go through the encapsulating layer26from one side to the other. An interconnection technology of this kind through the exterior of the chip is known as “chip-in-polymer” technology.

Here, the interconnections32and34are identical and only the interconnection32is described here below in greater detail.

FIGS. 2 to 5give a more detailed view of a particular embodiment of the interconnection32. The interconnection32has a mobile electrical pad40. This pad40is designed to get placed beneath the chip10facing one of the electrical contacts of this chip, in this case the contact19, to electrically connect the chip10to the substrate4. The width and the length of the pad40are far greater than its thickness. The term “far greater” refers to the fact that the width and the length are at least 5, 10 or 50 times greater than the thickness. The upper face of the pad40is plane, and has a surface area of at least 10 μm2and preferably at least 100 μm2so as to enable the creation of a robust and reliable electrical connection with the chip10.

The pad40can be shifted between a manufacturing position shown inFIGS. 3 and 4and a connection position shown inFIGS. 1 and 5.

In the manufacturing position, the pad40is situated solely within the level12. For example, in the manufacturing position, the pad40is separated from the face6of the substrate solely by the thickness of a sacrificial layer42(FIG. 3). For example, the thickness of the layer42is smaller than 10 μm.

In the connection position, the pad40rises above the substrate4. Here, the distance between the pad40and the face6of the substrate in the connection position is denoted as h (FIG. 5). This height h is greater than or equal to the thickness of the level12. Typically, the height h is greater than 20 μm or 100 μm.

Means for actuating the shifting of the pad40between these manufacturing and connection positions are provided in the device2. For example, here, the interconnection32also has 5 rectilinear arms44to48mechanically connected, at one end, to the pad40and, at the other end, to a respective fixed anchoring point on the face6. InFIG. 2, the anchoring points of the arms44to48are represented by squares of dashes, respectively 50 to 54. These anchoring points50to54are situated at different positions inFIG. 6.

The arms44to48extend in parallel to a same vertical plane55of which only the intersection with a horizontal face6is shown inFIG. 2. This plane55is perpendicular to the face6.

Here, this plane55is also a plane of symmetry for the pad40and the arms44to48. The pad40, the arm44and the anchoring point50extend on either side of the plane55.

In the manufacturing position (FIG. 3), the arms44to48extend also essentially in parallel to the face6.

Here, in the connection position, the arms44to48are inclined relatively to the vertical and the horizontal. For example, the angle between the direction in which the arm extends and the face6ranges from 5° to 85°.

Each arm44to48has a cross-section whose surface area is, for example, smaller than some μm2or some hundreds of μm2.

The end of each arm opposite the anchoring point is fixed to the pad40by a respective attachment point58to62.

Here, the attachment points58to60of the arms44to46are aligned in a same axis64perpendicular to the plane55. This alignment of the attachment points58to60is used here to adjust the height h with precision. The diagram ofFIG. 6explains the way in which the arms44to46act in order to fix the height h reached in the connection position. The axis46is situated on the circle arc C1whose center O is determined by the position of the anchoring point50. At the same time the axis64is situated on the circle arc C2whose center B is determined by the position of the anchoring points51and52. Should the length of the arm44be strictly greater than the length of the arms45and46, the height h of the pad40in the connection position is given by the following relationship:

k is the heat expansion coefficient of the material used to make the arms,

ΔT is the difference in ° C. between the temperatures in the manufacturing position and in the connection position,

L is the length of the arm44at the temperature T1of manufacture of the interconnection32,

y is the length of the arms45,46at the temperature T1.

Indeed when the interconnection32, having been manufactured, is cooled, then since the arm44is longer than the arms45and46, this interconnection no longer shrinks. This causes a tensile force to be exerted on the attachment point58which causes the pad40to be raised through the motion of the arms45and46which then act as levers until the height h is reached. Here, the arms which pull the pad40are called “actuating arms”, while the other arms which exert compression forces are called “lever arms”. In order that these means to actuate the shifting of the pad40may work, the centers O and B should no longer coincide. This condition is obtained by shifting the position of the anchoring points51and52along the axis X relatively to the position of the anchoring point50of the arm44.

Furthermore, the distance between the centers O and B should be sufficient to enable the exertion of a tensile force capable of lifting the pad40. This distance should however remain small enough to prevent the arm44from getting deformed by buckling. For example, this distance is determined experimentally with a simulation software program in taking account of the height h to be attained in the connection position.

Here, the pad40is rectangular. The attachment points59to62are positioned at each angle of the pad40to keep the upper face of the pad40parallel to the face6in the connection position. This arrangement of the attachment points59to62makes it possible to control the flatness of the pad40in the connection position. Preferably, this flatness must be controlled so that the distance between the highest point and the lowest point of the upper face of the pad40remains smaller than 50 μm and preferably smaller than 1 μm in the connection position. The length of the arms45to48is determined to control the flatness and parallelism of the upper face of the pad40relatively to the face6of the substrate. In the connection position, the upper face of the pad40is parallel to the face6.

The length of the arm44should not be equal to the length of the other arms. The lengths of the arms45and47are not necessarily the same.

For example, the length of the arms44to48is determined here by experiment. For example, to this end, a digital model of the interconnection32and of these deformations is simulated.

By way of an illustration, the different dimensions of an interconnection32are within the ranges defined in the following table:

Here, the arms44to48, the anchoring points50to54and the pad40are made out of one and the same electrically conductive material. Here, at least one of these arms fulfills the role of an electrical conductor electrically connecting the pad40to the tracks of the substrate4. For example, the material used is copper. More specifically, the interconnection32is made out of one and the same layer of this electrically conductive material.

FIG. 7shows an example of a method for manufacturing the device2.

Initially, at a step70, a wafer is provided. On this wafer, several devices2are made simultaneously. Thus, the conductive tracks of several microelectronic devices are made. This wafer can also integrate electronic components. To simplify the description ofFIGS. 8 to 28:

only one cross-section of this wafer corresponding to a single microelectronic device is illustrated at the different manufacturing stages,

only the manufacturing of the interconnection32is illustrated, and

the arms45to48of the interconnection32have been omitted.

FIG. 8shows the cross-section of the wafer corresponding to the device2at the very start of its manufacture. This wafer forms the substrate4on which conductive tracks22and24are deposited or etched. A dielectric layer72covers the entire face6of the substrate4except for the conductive tracks22and24.

Then, at a step74(FIG. 9), a sacrificial layer76is deposited on the substrate4. For example, this layer76is a resin.

At a step78(FIG. 10), the sacrificial layer76is structured, for example by lithography, to allow the sacrificial layer to remain solely on the pad40and the arms44to48.

Then, at a step80(FIG. 11), the sacrificial layer76is annealed so as to obtain a domed shape.

At a step82(FIG. 12), a metal layer84is deposited on the entire upper face6of the substrate4. This deposit is made for example at a depositing temperature T1greater than or equal to 200° C.

At a step86(FIG. 13), a layer88of photosensitive resin is deposited on the metal layer84and then structured by photolithography to make housings90in which metal micro-inserts have to be made.

At a step92(FIG. 14) a conductive metal material94is deposited in the housings90prepared during the step86. These metal deposits then form micro-inserts94directly deposited on the conductive layer84.

Then, at a step96(FIG. 15) the photosensitive resin88is eliminated so as to expose the micro-inserts94.

At a step98(FIG. 16), a new layer100of photosensitive resin is deposited on the substrate4and then structured, for example by photolithography so as to demarcate the locations at which the different conductive tracks of the substrate4and the interconnections32,34must be made.

At a step102(FIG. 17) the same layer84is etched to form the conductive tracks of the level12as well as interconnections32and34. These conductive tracks serve, for example, to connect at least one of the anchoring points of the arms50to54to the tracks22and24. These conductive tracks are fixed and are not led to shift subsequently.

At a step104(FIG. 18), the layer100of photosensitive resin is removed.

At a step106(FIG. 19), the sacrificial layer76is also eliminated and the temperature is lowered to a temperature T2. For example, the temperature T2is lower than or equal to 100° C. Here, the temperature T2is close to 80° C. The elimination of the sacrificial layer76releases the pad40and the arms44to48. The lowering of the temperature actuates the shifting of the pad40from its manufacturing position to its connection position.

At a step108(FIG. 20), the chip8is hybridized at the first level. At this step, a layer of bonder110is deposited at the position at which the chip should be bonded. The chip8is then deposited on this layer of border and put into electrical contact with the layer84and the tracks22,24by means of the micro-inserts94.

Then, at a step112(FIG. 21), a lateral encapsulation is made on the chip8. This encapsulation consists of the spreading of polymer all around the chip8and also, in this case, on its upper face. The pad40as well as the micro-inserts94implanted on this pad are entirely embedded in the encapsulating layer26. After deposition, the hardened layer26fixes the chip8definitively to the substrate4. The hardening of the layer26also immobilizes the interconnection32in its connection position

At a step116(FIG. 22), the encapsulating layer26is thinned and planarized by mechanical machining. For example, to this end the invention uses the CMP (chemical mechanical polishing) process. This thinning causes the micro-inserts94implanted on the pad40to be flush with the level of the upper face of the encapsulating layer26.

Then, at a step118(FIG. 23), the encapsulating layer26is etched on the thickness of the micro-inserts94so that the upper face of the pad40is now flush.

At a step120(FIG. 24), the second chip10is hybridized. The hybridizing of the second chip10is, for example, done as described for the step108. The chip10is stacked above the pad40so that its electrical contact19(not shown inFIG. 24) faces the pad40. The pad40is then electrically attached to the chip110by means of the micro-inserts94.

At a step122, the chip10is laterally coated.

Once this encapsulation has been done, at a step124, the different identical micro-electronic devices manufactured on the same wafer are separated from one another in a cutting-out step124.

At a step126, after this cutting-out step, the different microelectronic devices comprise chips stacked on one another are for example incorporated in packages equipped with lugs or connection pins enabling them to be connected to an electronic board or to an electrical circuit.

FIGS. 25 and 26represent another possible embodiment of an interconnection140liable to be used in the device2instead of the interconnection32or34. This interconnection140is distinguished from the interconnection32by the fact that only three arms are used instead of the five arms described here above.

They comprise:

a mobile pad142similar to the pad40, and

an arm144, for example identical to the arm44which extends in a vertical plane of symmetry146.

In this embodiment, the arms45and46are replaced by one and the same arm146. This arm146is obtained for example by joining the arms45and46to form only one plane extending beneath the arm144. The arms47and48also replaced by a single arm148obtained for example by joining the arms47and48of the interconnection32to form only one plane extending beneath the arm146.

An interconnection140of this kind is made by using several blocks149,150and152of sacrificial layers situated directly on respectively the pad142, the arm146and the arm144.

When the sacrificial blocks149,150and152are eliminated, they release the interconnection140, and the pad142can then be shifted from its manufacturing position shown inFIG. 25to a connection position.

FIG. 27shows another embodiment of a microelectronic device160. This device160is similar to the device2except that, in addition to the levels12and14, it has a third level162that is stacked above the level14and has a microelectronic chip164housed in it.

The chip164is electrically connected to the chips8and10by means of an interconnection166which electrically connects it directly to the upper face6of the substrate4. This interconnection166is made similarly to the interconnection32except that the arms are sized to raise the electrical pad168not to the same height as the pad40, but to an appreciably greater height so that this pad168is situated within the level162. For example, in the connection position, the pad128rises to a height h greater than or equal to twice the height h.

If necessary, micro-inserts are made between the upper face of one of the chips, and the lower face directly facing the chip of the upper level to directly connect the electrical contacts of these faces. By way of an illustration, inFIG. 27, the upper face of the chip8is connected to the lower face of the chip10by micro-inserts170which extend only vertically.

FIGS. 28 and 29show another possible embodiment of an interconnection180capable of electrically connecting the chips10and64ofFIG. 27.

To this end, the interconnection170has two pads182and184, similar to the pad40, connected to the substrate4by means of a common arm184and respective lever arms186to189and190to193.

The arm184fulfills the same function as the arm44. For example, the arm184is identical to the arm44except that it extends from an anchoring point up to the pad184in passing through the pad182.

The arms186to189and190to193fulfill the same functions as the arms45to48respectively in respect of the pads182and184.

FIG. 30shows an interconnection200identical to the interconnection32except that the lengths of the arms in the direction X have been modified. More specifically, in this embodiment, the length of arms44,47and48is strictly smaller than the length of the arms45and46. Preferably, the length of the arms44,47and48is at least two, three or four times smaller than the length of the arms45and46. For example, the length of the arm44is equal to the length of the arms47and48plus or minus 30%. Here, the lengths of the arms44,47and48are equal. In this embodiment, the arms45and46are actuation arms while the arms44,47and48are lever arms.

Many other embodiments are possible. For example, the micro-inserts94can be replaced by any means capable of connecting a contact of a micro-electronic chip to an electrical pad facing this contact. For example, a meltable ball can be used instead of the micro-inserts.

The conductive plates can be multi-layered plates with an adhesive sublayer.

Other means for actuating the shifting of the mobile pad can be used. For example, the electrical pad may be mechanically fixed to an actuation arm itself formed by a superimposition of several layers made out of materials having different coefficients of expansion. In this case, the actuation arm works as a bimetallic strip.

The actuation arm or arms can also be made out of a piezoelectric material so as to shift the mobile pad from the manufacturing position to the connection position. In this case, electrical tracks which can make the current flow in these piezoelectric arms are provided especially on the substrate4.

The mobile pad can also be shifted through the use of electrostatic forces. For example, to this end, the pad or one arm is fitted out with a conductive plate charged with a certain polarity and a plate of opposite polarity is formed, for example on the substrate, to repel the plate fixedly joined to the mobile plate.

The actuation means can also be magnetic means. For example, the pad or one of the arms is made out of a magnetic or magnetizable material. Facing these arms or pads made of magnetic material, a coil or a controllable magnet is created so as to repel the electrical pad or, on the contrary, attract this electrical pad. This coil will typically be formed on the face6of the substrate4.

In another embodiment, the actuation means are shape-memory materials. In this case, the shifting of the mobile pad between its manufacturing and connection positions is, for example, actuated by the passage of an electrical current.

The interconnection described here can also be used to electrically connect a microelectronic chip situated at a level N to a microelectronic chip situated at a lower level N−1, the level N−1 being strictly greater than 1. This amounts to making the interconnection on a substrate which already contains a microelectronic chip or a stack of microelectronic chips. For example, an interconnection similar to the interconnection32can be manufactured on the level12to directly connect the chip10to the chip164ofFIG. 27without using conductive tracks of the level12, i.e. the tracks etched on the substrate4. The method for manufacturing this interconnection is, for example, the same as the one described inFIG. 7except that the substrate on which the interconnection is made already includes the substrate4and the level12.

The pad40is not necessarily rectangular. For example it may be circular or have other shapes. In these latter cases, the width and the length of the pad correspond to the two most characteristic dimensions of the upper face of the pad. In the case of a circular face, the width and the length are equal to the diameter.

The lever arms or actuating arms are not necessarily rectilinear. For example, an arm may have a spiral shape.

The method described here enables the stacking and electrical connection of two or more levels of electrical components and thus the forming of a low-cost 3D type microelectronic device.

The encapsulating of the electrical components of each level can also be done after the pads are shifted to their connection position or after the electrical components of the upper levels are connected to these pads. Thus, a single encapsulating step is implemented to coat several levels at the same time.