For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which:
As is illustrated in
A third passivation layer 6, which may be used for example in die arrangements for DRAM products, is optionally arranged on the first passivation layer 5, likewise whilst leaving free the bonding pads 2. Said third passivation layer 6, which for example has a layer thickness of approximately 5 μm and may be produced form a polyimide, may serve as an additional stress buffer.
Arranged on the bonding pads 2 is in each case a connecting element 3, 31, which are in each case associated with an electrically conductive structure arranged for enabling a redistribution wiring at the die.
As can furthermore be seen from
As can furthermore be seen from
As can furthermore be seen from
The covering layer 9 may be formed as a protective layer or else as a soldering resist for the use as wafer level chip size packages (CSP). The covering layer 9 may be applied for example, by screen printing or some other suitable application method.
Since the molding layer 7 is applied to the first passivation layer 5, or alternatively to the third passivation layer 6 provided that such a third passivation layer is provided, for example by means of a molding method or a printing method, the molding layer 7 can be produced with a thickness of >30 μm. On account of the molding material used, which may have for example an epoxy resin mixed with corresponding fillers, what may be achieved, even in the case where the molding layer has a layer thickness of approximately 50 μm, is that no or an only very negligible shrinkage of the molding material takes place during the curing of the molding material, with the result that flexure of the die is avoided. Since, furthermore, the curing temperature of the molding material after molding or printing is a maximum of 180° C., this has the effect that the retention yield loss is lower than when using a polyimide which is applied by means of a spin-on process in accordance with the conventional production of a passivation layer.
Since, in accordance with one embodiment of the invention, as already specified, the second passivation layer 7, sometimes referred to herein as the molding layer 7, can be formed with a thickness of greater than 30 μm between the first passivation layer 5 and the redistribution layers 8 arranged on the top side of the molding layer 7. Thus, it is advantageously achieved that the parasitic capacitances can be decisively reduced, so that the die arrangement consequently enables a significant improvement of the electrical performance at high clock frequencies, in conjunction with better signal transmission. A further advantage of the die arrangement in accordance with one embodiment of the invention is that the second passivation layer 7, in which the connecting elements 3, 31 are essentially encapsulated and by means of which the increased distance between the active die surface and the redistribution layer 8 is provided, can be produced by molding or printing. Consequently, for the production of said second passivation layer 7, it is not necessary to provide a material which has to be photopatternable. The molding material used for producing the second passivation layer 7 not only has more favorable processing properties but can also be provided at lower cost.
Yet another advantage of the molding or printing of the second passivation layer 7 and of the molding material which is to be used for this purpose and which does not have to be photopatternable furthermore consists in the fact that additional fillers may be admixed with the molding material, which may have an epoxy resin for example, by means of which fillers the coefficient of thermal expansion (CTE) of the molding material and/or the dielectric constant of the molding material can be influenced in a targeted manner in a desired way. A suitable filler with regard to influencing the coefficient of thermal expansion may be a silicon dioxide (spherical filler amorphous), for example.
Furthermore, it is possible to admix with the epoxy resin further or other fillers, which may for example influence the shrinkage behavior during curing, the thermal conductivity of the molding material and also, for example, specific mechanical properties, so that for forming the second passivation layer 7 it is possible to provide a molding material which has a desired or required castability and also desired or required mechanical, thermal and electrical properties and can form a composite structure with the first passivation layer 5 or with the second passivation layer 6, if present, and with the connecting elements 3, 31.
The connecting element 3, shown in
Prior to the production or the deposition of the bumps 3, usually after the processing of a start layer (seed layer) and the formation of a corresponding structure made of photoresist, an under bump metallization (UBM) is applied to the die 1 directly onto the opened bonding pad structure. This is followed by the electrodeposition of the bumps 3, which may have copper, for example, it being possible for the bumps 3 to be formed in pillar-type fashion on account of the structure made of photoresist. After the subsequent removal of the photoresist and the start layer, the die 1 may then be provided with the molding layer 7 (
Instead of the electrodeposited connecting elements 3 described with reference to
As can be seen from
As illustrated in
Since such a third passivation layer 6 is not absolutely necessary for the die arrangement in accordance with one embodiment of the invention, the illustration of said third passivation layer 6 is dispensed with in the subsequent Figures and the associated description.
The next method process in the production of the die arrangement in accordance with one embodiment of the invention involves effecting, as is illustrated in
As can be seen from
For the case where the stud bumps 31 on the die 1 are completely embedded in the molding layer 7 during the molding or printing operation, as is shown in
In a next method process, as illustrated in
Since the stud bumps 31 or the electrodeposited bumps 3 which are embedded in the molding layer 7 then have copper or gold rather than aluminum, like the original bonding pads 2, it is possible, in order to achieve sufficiently good adhesion properties of the redistribution layers 8 with the stud bumps 31 or bumps 3, prior to the processing of the redistribution layers 8, optionally to use a chemical metallization instead of applying an electroplating start layer, which requires an upstream thin-film process. Afterward, the redistribution layers 8 may essentially be effected by means of a customary electrodeposition process using a previously formed mask, firstly the redistribution layers 8, which have copper, and onto these a covering layer being processed, which, depending on the further purpose of use of the die arrangement, for example for wire bonding or solder bonding, may have for example nickel (Ni) or gold (Au) or an alloy thereof and ensures the solderability of the redistribution layers 8.
Since, in accordance with an embodiment of the invention, the passivation layer arranged between the active surface of the die 1 and the redistribution layers 8 is a molding layer 7 having molding material, such a layer may be formed with a thickness of 50 μm, for example, with the result that parasitic capacitances between the active surface of the die 1 and the redistribution layers 8 can be excluded or prevented to the greatest possible extent even at high operating frequencies. Consequently, the electrical performance of the die arrangement according to an embodiment of the invention is significantly improved compared with conventional die arrangements. Moreover, the molding material may have added to it additives that can influence for example the dielectric constant of said molding material in a desired manner, so that the molding layer 7 may have the improved properties not only by way of its thickness but also on account of its material. It is possible to admix additives or fillers with the molding material because, as already mentioned, the molding layer 7 can be applied to the die 1 in a molding process or a printing process and, consequently, does not need to have photopatternable properties. A further advantage of forming the second passivation layer from molding material is that the retention yield loss is reduced at molding temperatures of typically 180° C.
As can be seen from
An alternative configuration of the covering layer 9 is shown in
Although not illustrated separately, in the production phase for the die arrangement shown in
Subsequently, including the optional reduction of the thickness of the die 1, it is possible, as can be seen from
As can be seen from
Said sections free of molding layer 7 may furthermore be utilized, for example, as alignment markings for the processing of the redistribution layers 8 that are affected after the molding of the second passivation layer (molding layer 7).
Another possibility for the alignment of the redistribution layers 8 that are to be arranged after the molding of the second passivation layer (molding layer 7) is illustrated in
The die arrangement produced, for example, at the wafer level in accordance with one embodiment of the invention may, as already mentioned, be singulated into individual completed dies after, for example, the arrangement of the solder balls 20 (
602 involves effecting formation of at least one connecting element on a first electrical connection of at least one first electrical connection region of a die with a multiplicity of electronic circuits that are electrically coupled to one another, at least one first electrical connection region, in which at least one first electrical connection is arranged, and a first passivation layer, which is applied on the upper surface of the die and leaves free at least the first connection, in such a way that the connecting element extends approximately vertically from the electrical connection.
604 involves effecting formation of a second passivation layer made of a molding material on the first passivation layer whilst molding in the at least one connecting element.
606 involves effecting formation of at least one redistribution layer on the surface of the second passivation layer whilst producing an electrical connection to the free end of the at least one connecting element.
The die arrangement in accordance with one embodiment of the invention has a die with a multiplicity of electronic circuits that are electrically coupled to one another, at least one first electrical connection region, in which at least one electrical connection is arranged, and a first passivation layer, which is applied whilst leaving free at least the one first electrical connection region on the upper surface of the die. A second passivation layer, which has a molding material, is arranged at least partly on the first passivation layer. Furthermore, the die arrangement has at least one electrically conductive structure with a connecting element and a redistribution layer for electrically connecting the first electrical connection region to a second electrical connection region, which is formed by or at a section of the redistribution layer, the connecting element extending from the first electrical connection region through the first passivation layer and the second passivation layer and the redistribution layer coupled to the connecting section being arranged at least partly on the second passivation layer.
The second passivation layer of the die arrangement may be produced by means of a molding method.
As an alternative, the second passivation layer may be produced by means of a printing process, such as a vacuum printing encapsulating process, for example.
The die arrangement is distinguished by the fact that the redistribution layer is arranged on the second passivation layer having a molding material.
Since the second passivation layer having a molding material can be produced by means of a molding process or a printing process, the molding layer can be provided with a correspondingly larger layer thickness, thereby achieving a reduction of parasitic capacitances in the high performance range. Since the second passivation layer can be produced by means of a molding process or a printing process, and the molding material is typically cured at lower temperatures than a passivation layer made of a conventional dielectric applied in a spin-on process, retention losses can be reduced or even avoided. Furthermore, on account of the material of the second passivation layer, despite a larger layer thickness, the die flexure can be reduced since the molding material has little shrinkage.
The die arrangement in accordance with one of the embodiments of the invention may be used, for example, for products or technologies regarding dual die package (DDP), wafer-level-package on board (WLPoB), flip-chip-in-package (FCiP), thru-silicon-via (TSV) and 3D integration.
The second passivation layer of the die arrangement may have a thickness of approximately 10 μm to 100μm.
The second passivation layer of the die arrangement has a thickness of approximately 50 μm.
The die arrangement may have a third passivation layer between the first passivation layer and the second passivation layer.
The third passivation layer may have polyimide.
The third passivation layer may have a thickness of approximately 1 μm to 10 μm.
The molding material of the second passivation layer of the die arrangement may have an epoxy resin.
Furthermore, the molding material may contain fillers that influence the coefficient of thermal expansion (CTE) of the molding material.
Furthermore, the molding material may contain fillers that influence the dielectric constant of the molding material.
The molding material has a curing temperature of less than or equal to approximately 180° C.
The connecting element of the electrically conductive structure of the die arrangement may be an electrodeposited bump.
The bump may contain copper.
The connecting element of the electrically conductive structure may be a mechanically fitted stud bump.
The stud bump may contain copper or gold.
The stud bump may be a stack bump.
A covering layer may be applied on the redistribution layer of the die arrangement whilst leaving free at least the one second electrical connection region.
The die of the die arrangement may have a multiplicity of memory cells.
The die arrangement may have an additional die, the die and the additional die being arranged one above another.
In accordance with a farther embodiment of the invention, a method for producing a die arrangement is provided. The method includes formation of at least one connecting element on a first electrical connection of an at least one first electrical connection region of a die with a multiplicity of electronic circuits that are electrically coupled to one another, at least one first electrical connection region, in which at least one first electrical connection is arranged, and a first passivation layer, which is applied on the upper surface of the die and leaves free at least the first connection, in such a way that the connecting element extends approximately vertically from the electrical connection, and formation of a second passivation layer made of a molding material on the first passivation layer whilst molding in the at least one connecting element, formation of at least one redistribution layer on the surface of the second passivation layer whilst producing an electrical connection to the free end of the at least one connecting element.
Furthermore, the method may include the formation of at least one second electrical connection region with a second electrical connection at the redistribution layer by arranging a covering layer on the top side of the second passivation layer whilst leaving free at least one section at the at least one redistribution layer.
The method may furthermore include the formation of the second passivation layer by means of a molding process.
In accordance with another configuration, the formation of the second passivation layer may be effected by means of a printing process.
The printing process may be for example a vacuum printing encapsulating process (VPES).
In accordance with a further configuration of the method, the at least one connecting element may be formed in a maskless method process.
In accordance with an alternative configuration of the method, the formation of the at least one connecting element on the electrical connection may be effected by mechanical application of a stud bump.
The stud bump may be produced for example by arranging at least two stud bumps one above another.
As an alternative to this, the formation of the at least one connecting element on the electrical connection may be effected by electrodeposition of a bump.
In accordance with one embodiment of the invention, the formation of the bump includes formation of a seed layer, formation of a mask made of a photoresist, electrodeposition of the bump, formation of a seed layer thereon, and removal of the photoresist.
By way of example, a third passivation layer may be arranged prior to the formation of the at least one connecting element on the surface of the first passivation layer whilst leaving free at least the one first electrical connection region.
Furthermore, the formation of the covering layer may be effected by means of screen printing.