CN104810297A - Method for manufacturing a flip chip circuit device and the flip chip circuit device - Google Patents

Abstract

The invention relates to a method for producing a flip-chip circuit arrangement, the method having at least the following steps: producing or providing a circuit carrier having a first surface and contact areas applied to the first surface and having a second surface and applying To the semiconductor component at the contact location on the second surface, applying a first contact element to the connection surface, applying a second contact element corresponding to the first contact element to the contact location, such that the first contact element is planarized such that The contact surfaces of the first contact unit define a common first contact plane within a first tolerance, the adhesive is applied to the first contact unit and/or the second contact unit, the semiconductor component and the circuit carrier are pressed to form the first and The electrical connection between the second contact units and the hardening of the adhesive in order to produce a mechanical connection between the semiconductor component and the circuit carrier.

Description

Method for producing flip-chip circuit arrangement and flip-chip circuit arrangement

technical field

The invention relates to a method for producing a flip-chip circuit arrangement and a corresponding flip-chip circuit arrangement.

Background technique

In flip-chip assembly technology, for example, monolithic semiconductor components (chips, dies) are mounted and connected with their active contact sides directly onto a circuit carrier, for example a substrate or a circuit board. In this case, the contact points of the semiconductor components are connected to contact areas on the circuit carrier, for example conductor tracks, without connecting wires (wire bonding). A small area requirement can thus be achieved.

For this purpose, stud bumps, for example made of gold, are applied to the contact points of the semiconductor components and subsequently laid down on the conductor tracks of the circuit carrier, wherein the stud bumps correspond to those produced by conventional The spherical bond formed by the Ball-Wedge-Bonden method. Then, the semiconductor component is pressed onto the circuit carrier, so that the electrical connection is formed with the conductor tracks and stud bumps partially deformed. In the flip-chip method by means of a non-conductive adhesive (NCA, non-conductive adhesive), an adhesive is placed between the chip and the circuit carrier before or after pressing, which then hardens.

Especially in the case of an uneven surface of the circuit carrier, which transitions into the surface of the conductor tracks, unreliable electrical contacting can occur when the stud bumps are pressed, because due to the unevenness, local Different pressing forces take effect. As a result, the conductor track can be easily damaged or mechanically deformed due to its small height, and the circuit carrier lying beneath it can also be plastically deformed. Furthermore, each protruding area can lead to damage or mechanical fastening.

For this purpose, a flip-chip connection is proposed in WO 02/056345 A2, in which the stud bumps are applied not only to the contact points of the semiconductor components but also to the conductor tracks Or on the contact pads of the circuit carrier. In order to form a homogeneous contact surface, the stud bumps are flattened by embossing, so that unevennesses on the circuit carrier and semiconductor component that are also transferred to the contact surface are compensated, and thus the contact of the stud bumps The surfaces lie approximately at approximately the same height above the circuit carrier or the semiconductor component. Next, the stud bumps of the semiconductor component and of the circuit carrier are placed on top of each other in alignment and bonded together in a bonding method by heating, pressing against each other and additionally ultrasonically treating the stud heads bumps so that the contact material spreads over the contact surface of the two stud bumps. An electrical connection and a mechanical connection are thus formed.

Contents of the invention

It is provided according to the invention that the circuit carrier, in particular an injection-molded circuit carrier (molded interconnect device, MID, molded interconnect device), and preferably monolithic semiconductor components (chip, bare chip) are connected and connected to each other in a flip-chip method, In this case, the first contact unit connected to the circuit carrier and planarized is pressed against the second contact unit applied to the semiconductor component, and the adhesive which at least partially surrounds the two contact units is additionally cured in order to permanently Ground connects two contact units pressed against each other. A flip-chip circuit arrangement is thus constructed.

Here, the first and second contact elements are preferably embodied as gold nuggets or gold balls, so-called stud bumps, which are similar to ball bonds in the ball-wedge bonding method. The ground is applied to the contact points on the semiconductor component and to contact areas on the circuit carrier, for example conductor tracks plated with galvanic structures such as copper, nickel/phosphorus and gold.

Some advantages can already be achieved by this.

The use of stud bumps on the two components to be connected thus achieves that the connection surfaces arranged between the circuit carrier and the stud bumps, which are used, for example, as conductor tracks, are less strongly pressed when pressed. under pressure. Thus, due to the stud bumps applied to the conductor tracks, the "deformation plane" is moved from the conductor tracks, preferably upwards into the stud bumps when pressed, and thus the acting surface load is directed upwards from the circuit carrier and the conductor tracks. Migration, so that when pressing, the force mainly acts on the contact surface of the stud bump and only a small amount of force transmitted through the stud bump acts on the conductor track. As a result, for example, peaks in the surface load that can lead to damage to the circuit carrier and the conductor tracks can be greatly reduced, and deformation of the conductor tracks and the circuit carrier produced from plastic can thus be avoided; the reliability of the contacting is improved.

Furthermore, irregularities on the surface of the circuit carrier, which may be in the order of 10 μm-20 μm, can be compensated for by the planarization of the first contact unit. This has the advantage during flip-chip manufacturing that damage to the contact elements during pressing due to the individual protruding contact elements can be prevented.

Within the scope of the present invention, flattening or flattening is understood here to mean that the contact surface is at least partially adapted to the first contact unit, ie lies within a tolerance in the first contact plane. This can be ensured, for example, mechanically, for example by a stamp placed on the contact surface or by material erosion, for example by laser ablation. However, other methods of moving the contact surface into the plane or into the contact plane are also conceivable. During planarization, the area of the contact surface is preferably also slightly increased, since during planarization the contact material is also partly pushed away to the side. In this case, tolerances are in particular production-dependent tolerances, for example due to the roughness of the punch or other processing precision occurring during the planarization process, which tolerances may lie in the range of several hundred nanometers.

Unlike in the bonding process provided in WO 02/056345A2 in which the contact elements are pressed against each other, heated and treated with ultrasound, according to the invention preferably no diffusion of the contact material, such as gold, takes place; therefore , the contact elements are not welded, in particular during bonding, but according to the invention are preferably pressed one above the other and held close together only by the hardened adhesive.

As a result, the manufacturing outlay can advantageously be kept low, since no additional method steps are required during the manufacturing, such as, for example, treatment by means of ultrasound. Furthermore, additional requirements for contacting the unit and the entire flip-chip circuit arrangement can be avoided by omitting the ultrasonic treatment.

The adhesive is preferably applied to the circuit carrier prior to pressing in such a way that it preferably completely covers the first contact element and the contact surface, wherein the adhesive can also be distributed on the directly adjacent connection areas (conductor tracks). )superior. In this case, for example, the amount of adhesive is selected such that the adhesive completely fills the gap between the circuit carrier and the semiconductor component after the two contact units have been pressed, ie lies essentially completely against the circuit carrier and the semiconductor component. surface in order to increase the stability of the mechanical connection of the two elements after hardening. In this case, the mechanical bonding is preferably achieved only by the adhesive connecting or bonding the semiconductor component to the circuit carrier and thus holding the contact units close to one another. In principle, it is also possible for an adhesive to be applied additionally or instead to the surface of the semiconductor component.

Next, the second contact elements of the semiconductor component, which form the second contact plane within manufacturing-determined tolerances, are aligned relative to the first contact elements and approach each other until they touch, wherein the first and second contact The planes lie parallel to each other. Subsequently, the second contact unit is pressed onto the first contact unit, so that the adhesive is extruded to the side and spreads on the side around the contact unit, also in the region of the contact surface. The contact surfaces of the two contact units are thus in electrical contact with respect to each other, ie the adhesive is almost completely squeezed out of the gap between the contact surfaces.

In this case, the adhesive is, for example, a non-conductive adhesive (NCA, non-conductive adhesive), in order to advantageously prevent an electrical connection of contact surfaces and stud bumps adjacent to one another to one another via the adhesive. It is also conceivable to additionally use a conductive adhesive, for example a silver conductive glue, which is applied, for example, only locally in the region of the contact surface, preferably before applying the non-conductive adhesive. When pressing, the non-conductive adhesive is first extruded until the two contact elements touch the conductive adhesive and the electrically conductive adhesive is also extruded, wherein the electrically conductive adhesive is then also at least partially It may remain in the gap between the contact surfaces in order to compensate eg small tolerances. Furthermore, the electrical transition can be improved, since inclusions of non-conductive adhesive between the contact surfaces can be reduced or avoided.

In order to harden the adhesive, the adhesive is preferably heated. For this purpose, depending on the adhesive, a temperature of approximately 250° is set. Helpfully, the temperature increase also heats the contact unit, whereby it becomes softer and can thus be deformed more easily. Diffusion of the contact material, ie welding of the contact elements together, is thus preferably not achieved.

An adaptation of differently shaped contact surfaces to one another can also be advantageously achieved by heating the contact unit. In this case, during pressing, for example, the respective protruding regions of the one contact surface are mechanically deformed in such a way that they are adapted to the opposite contact surface and thus improve the electrical transfer.

Here, the manufacturing steps may vary. Thus, for example, the application of the second contacting unit is independent of the application and planarization of the first contacting unit, ie can take place before or after it in time.

Description of drawings

The accompanying drawings show:

FIG. 1 shows a schematic view of the circuit carrier and the semiconductor components before switching them on,

FIG. 2 shows the circuit carrier according to FIG. 1 with applied contact areas,

FIG. 3 shows the circuit carrier according to FIG. 2 with a first contact unit applied to the contact surface,

Figure 4 shows the step of planarizing the first contact unit,

Figure 5 shows the flip-chip circuit arrangement before switching on,

Figure 6 shows a turned-on flip-chip circuit arrangement, and

Fig. 7 shows a flow chart of the method according to the invention.

Detailed ways

In order to construct the flip-chip circuit arrangement 3 shown in FIG. 6, a circuit carrier 1 is first provided according to FIG. A wafer of semiconductor components 2 or a chip or a bare chip. The circuit carrier 1 is produced from a non-conductive material, preferably plastic, and has an uneven surface 4 , wherein irregularities can occur during production and by additional surface treatment (laser treatment). The chip 2 has a surface 5 on which a plurality of mutually isolated contact points 6 , for example contact pads, which are connected to an integrated switching circuit in the chip 2 , are arranged.

To connect the circuit carrier 1 to the chip 2 it is first provided that contact areas 7 are applied to the circuit carrier 1 - for example conductor tracks and/or contact pads - or the circuit carrier 1 is provided with already processed contact areas 7 . For this purpose, according to FIG. 2 , for example, an electrically conductive layer is applied in an electroplating process—for example, corresponding electroplating structures made of copper, nickel/phosphorus and gold—onto the surface-treated surface 4 , so that as far as possible no Defective contact surface 7. In this case, contact surface 7 forms a circuit pattern which extends over surface 4 substantially in x-direction and y-direction, wherein in the drawing the y-direction is oriented perpendicular to the drawing plane. The height, ie, the extent in the z-direction, of contact areas 7 distributed over surface 4 is approximately equal and is approximately 10 μm to 20 μm.

Due to the unevenness of the circuit carrier 1, the connection surfaces 7 are displaced relative to each other in the z direction, ie the relative positioning in the z direction changes; therefore, unevennesses on the surface 4 are also transferred to the connection surfaces 7 on.

In order to compensate for this displacement, it is provided in particular in the method according to the invention that a first contact unit 8 . 1 , 8 . 2 is applied to contact surface 7 ( St1 ). In this case, the first contact units 8.1, 8.2 are embodied as so-called stud bumps. These stud bumps are applied to contact surface 7 in a bonding method, for example as part of conventional ball-and-wedge bonding.

For this purpose, the tip of the ball wedge bond is brought over contact surface 7 and the gold wire protruding from the tip is then heated so that the gold melts and forms a ball due to surface tension. The ball is pressed or bonded to the contact surface 7 by means of short ultrasonic pulses, so that an electrical connection is produced between the contact surface 7 and the ball. Next, cut the gold wire just above the ball. The balls and the snipped gold wires form stud bumps, the first contact units 8.1, 8.2. In this case, the height 9.1, 9.2 of the stud bumps is approximately 50 μm and can have a production-dependent tolerance of approximately 1 μm-2 μm.

Furthermore, after application of the first contacting units 8.1, 8.2, the first contacting units are displaced relative to one another in the z-direction, since unevennesses of the surface 4 are also transferred via the contact surface 7 to the stud bumps 8.1, 8.2, as can be seen especially in FIG. 3 . The production-specific tolerances of the stud bumps can largely be kept out of consideration, since they are negligible with respect to irregularities of the surface 4 which may lie in the range of 10 μm-20 μm.

In order to compensate for said unevenness, in the following step St2 the first contact elements 8.1, 8.2 are planarized, ie their heights 9.1, 9.2 are adapted in such a way that the contact surfaces 10.1, 10.2 of all first contact elements 8.1, 8.2 are The first tolerance 20 lies in a common first contact plane 11 , which according to FIG. 4 extends in the x-y direction.

For planarization, according to this implementation, a punch 12 with a flat underside 13 is used which extends over the entire circuit carrier 1 or covers at least one region when laid on said circuit carrier, to be The planarized first contact unit 8 . 1 , 8 . 2 is arranged on the circuit carrier 1 in the at least one region. The position of the punch 12 or the underside 13 can be adjusted in all three spatial directions, for example by a servomotor 12.2 controlled by the control device 12.1.

For this purpose, the punch 12 is brought close to the first contact unit 8 . 1 , 8 . 2 from above by the servomotor 12 . 2 and is oriented such that the underside 13 is parallel to the previously determined first contact plane 11 . The underside 13 then travels downwards to such an extent that it touches the respective protruding first contact unit 8.1, 8.2 or their contact surface 10.1, 10.2. Subsequently, the punch 12 is pressed with a uniform force in the pressing direction R onto the contact surfaces 10.1, 10.2, so that the first contact elements 8.1, 8.2 are mechanically deformed, thereby reducing the height 9.1, 9.2 of said first contact elements and making The contact surface 10.1, 10.2 of each contact unit 8.1, 8.2 is flat and thus slightly increases the area of the contact surface. The punch 12 is pressed approximately until the underside 13 touches all contact elements 8 . 1 , 8 . 2 and thus also the contact elements 8 . 1 , 8 . Overall, the punch 12 is adjusted so strongly in the pressing direction R that all contact surfaces 10 . 1 , 10 . , 10.2 smooth.

The first contact plane 11 , to which the second contact units 15 . 1 , 15 . 2 arranged on the semiconductor component 2 can be applied, is thus achieved by planarization. Here, the second contact units 15.1, 15.2 are likewise designed according to FIG. Face 7 together. The second contact unit 15.1, 15.2 delimits with its contact surfaces 16.1, 16.2 a second contact plane 17 which, depending on production, may have a second tolerance 21 of 1 μm-2 μm.

Before the second contact unit 15.1, 15.2 is applied to the first contact unit 8.1, 8.2, in step St3, an adhesive 18—such as a non-conductive epoxy glue (NCA, non-conductive adhesive: non-conductive adhesive) Agent) is applied to the surface 4 of the circuit carrier 1 in such a way that the first contact units 8.1, 8.2 and also the surrounding area are completely covered, as shown in particular in FIG. 5 . In addition, the electrically conductive adhesive 18.1 can be locally applied to the contact surfaces 10.1, 10.2 before the non-conductive adhesive 18 is applied, without two adjacent first contact units 8.1, 8.2 thus not being brought into contact with each other. The semiconductor component 2 is then aligned relative to the circuit carrier 1 in such a way that the second contact units 15 . 1 , 15 . 2 corresponding to the first contact units 8 . 1 , 8 . 2 are positioned one above the other and the planes 11 and 17 are parallel to each other. Subsequently, in step St4, the semiconductor component 2 is brought closer to the circuit carrier 1 until the second contact elements 15.1, 15.2 touch the first contact elements 8.1, 8.2 and are thus pressed against each other such that the adhesive 18 is forced to the sides And it is laid around the two contact units 8.1, 8.2, 10.1, 10.2 and preferably completely surrounds them. In this case, the gap between circuit carrier 1 and semiconductor component 2 is preferably completely filled with adhesive 18 , as shown in FIG. 6 . The electrically conductive adhesive 18.1 is also squeezed out to the sides, but remains at least partially in the gaps between the contact surfaces 10.1, 10.2, 16.1, 16.2.

In order to permanently connect the two contact units 8.1, 8.2, 15.1, 15.2 to each other, the adhesive 18 is hardened in the following step St5; Stretched onto the circuit carrier 1. The adhesive 18 is therefore responsible for the fastening of the two contact units 8.1, 8.2, 15.1, 15.2. The mechanical fastening is therefore preferably firstly achieved by means of an adhesive 18 which holds the semiconductor component 2 on the circuit carrier 1 . For hardening, at least the area around the contact surfaces 8.1, 8.2, 15.1, 15.2 is heated, the temperature being adjusted to within 250° depending on the adhesive 18.

Helpfully by heating, the contact surfaces 10.1, 10.2, 16.1, 16.2 also become softer, so that they can be adapted to one another when pressed due to mechanical deformation, ie the contact surfaces 10.1, 10.2, 16.1, 16.2 can be additionally compensated Small irregularities and tolerances determined by manufacturing. After hardening of the adhesive 18 , the flip-chip circuit arrangement 3 according to FIG. 6 is completed.

Claims (16)

1. A method for manufacturing a flip-chip circuit arrangement (3), said method having at least the following steps: Production or provision of a circuit carrier (1) with a first surface (4) and contact areas (7) applied to the first surface and with a second surface (5) and contact surfaces (7) applied to the second surface contacting the semiconductor component (2) (St0) at the position (6), applying a first contact unit (8.1, 8.2) to said connection surface (7) (St1), applying a second contact unit (15.1, 15.2) corresponding to said first contact unit (8.1, 8.2) onto said contact location (6) (St1.1), The first contact unit (8.1, 8.2) is planarized in such a way that the contact surfaces (10.1, 10.2) of the first contact unit (8.1, 8.2) define a common first contact plane(11)(St2), applying adhesive (18) to said first contact unit (8.1, 8.2) and/or said second contact unit (15.1, 15.2) (St3), pressing the semiconductor component (2) and the circuit carrier (1) to form an electrical connection (St4) between the first and second contact unit (8.1, 8.2, 15.1, 15.2), and The adhesive (18) is cured in order to produce a mechanical connection between the semiconductor component (2) and the circuit carrier (1) (St5). 2. The method according to claim 1, characterized in that the second contact unit is aligned on the first contact unit (8.1, 8.2) corresponding to the second contact unit before the pressing (15.1, 15.2). 3. The method according to claim 2, characterized in that, during the alignment, the contact surface (16.1, 16.2) of the second contact unit (15.1, 15.2) is approximately within a second tolerance (21) A second contact plane (17) defined therein adjusts in parallel to said first contact plane (11). 4. The method according to any one of the preceding claims, characterized in that the adhesive (18) is applied to the circuit carrier (1) in such a way that the first and/or second contacts The unit (8.1, 8.2, 15.1, 15.2) is completely covered and the adhesive (18) rests against the first surface (4) and the second surface (5) after the pressing. 5. The method according to any one of the preceding claims, characterized in that the adhesive (18) is a non-conductive glue and thus presses the semiconductor component (2) and the circuit carrier (1) , so that the adhesive (18) is at least partly released from the contact surface (10.1, 10.2) of the first contact unit (8.1, 8.2) and the contact surface (16.1) of the second contact unit (15.1, 15.2) , 16.2) Extruded in the gap between. 6. The method according to any one of the preceding claims, characterized in that an electrically conductive adhesive (18.1) is additionally applied locally to the first contact unit before applying the adhesive (18) (8.1, 8.2) on said contact surface (10.1, 10.2) and/or on said contact surface (16.1, 16.2) of said second contact unit (8.1, 8.2). 7. The method as claimed in any one of the preceding claims, characterized in that the adhesive (18) is heated for hardening. 8. Method according to any one of the preceding claims, characterized in that the step of planarization is carried out mechanically. 9. The method according to claim 8, characterized in that the flattening is carried out by means of a punch (12) with a flat underside (12), wherein the punch (12) is brought close to the The contact surface (10.1, 10.2) of the first contact unit (8.1, 8.2) and then the punch is advanced with a constant force in the pressing direction (R) such that the first contact unit (8.1, 8.2 ) deformation. 10. The method according to any one of the preceding claims, characterized in that the first and/or second contact elements (8.1, 8.2, 15.1, 15.2) are applied by ball bonding in order to form stud bumps . 11. The method according to any one of the preceding claims, characterized in that an injection-molded circuit carrier made of plastic, such as a MID (molded interconnect device: molded interconnect device) is used as circuit carrier (1) And a monolithic component is used as the semiconductor component (2). 12. A flip-chip circuit arrangement (3) having at least: A circuit carrier (1) having a plurality of contact areas (7) on which first contact units (8.1, 8.2) are applied, a semiconductor component (2) with a contact location (6) to which a second contact unit (15.1, 15.2) is respectively applied, Therein, the first contact unit (8.1, 8.2) has a contact surface (10.1, 10.2) which is located in the first contact plane (11) within a first tolerance (20), and the contact surface is in contact with said second contact unit (15.1, 15.2), Wherein, said first contact unit (8.1, 8.2) and said second contact unit (8.1, 8.2) pass through an adhesive which at least surrounds said first and second contact unit (8.1, 8.2, 15.1, 15.2) (18) are mechanically connected to each other. 13. Flip-chip circuit arrangement (3) according to claim 12, characterized in that the first and second contact elements (8.1, 8.2, 15.1, 15.2) are only passed through the adhesive (18) A mutual mechanical connection, wherein the adhesive (18) rests on the first surface (4) of the circuit carrier (1) and on the second surface (5) of the semiconductor component (2). 14. The flip-chip circuit device (3) according to claim 12 or 13, characterized in that, the circuit carrier (1) is an injection-molded circuit carrier made of plastic, such as a MID (molded interconnect device: molded plastic interconnect devices). 15. The flip-chip circuit arrangement (3) according to any one of claims 12 to 14, characterized in that the first and/or second contact unit (8.1, 8.2, 15.1, 15.2) is a nail Head bumps. 16. The flip-chip circuit device (3) according to any one of claims 12 to 15, characterized in that, the adhesive (18) is a non-conductive glue, and on the contact surface (10.1, 10.2, 16.1, 16.2) is additionally provided with electrically conductive adhesive (18.1).