This application claims priority to German Patent Application 10 2011 101 035.5 which was filed May 10, 2011, and is incorporated herein by reference.
Exemplary embodiments of the invention relate to a method for producing a connection region on a side wall of a semiconductor body and to a method for producing a semiconductor module having a connection region on a side wall.
Semiconductor modules having connection regions on a side wall are necessary, for example, for CSP (chip size package) module housings in which a connection region is formed on a side wall of a semiconductor body in a particularly space-saving design, wherein this connection region is insulated from the semiconductor body by a side wall insulation layer. Such a design is described, for example, in DE 10 2005 004 160 A1.
In one aspect, the invention provides a method for producing a connection region on a side wall of a semiconductor body and a method for producing a semiconductor module having a side wall connection region.
One embodiment of the method for producing a connection region on a side wall of a semiconductor body. At least a first trench is formed at a first surface of the semiconductor body and extends into the semiconductor body. And electrical insulation layer is formed on the side walls and on the bottom of the first trench such that the first trench is only partially filled. The still unfilled part of the first trench is filled with an electrically conductive material. A separating trench is formed along the first trench in such a way that a side wall of the separating trench directly adjoins the first trench. The part of the insulation layer that adjoins the separating trench is at least partially removed, with the result that at least some of the electrically conductive material in the first trench is exposed.
The method provides, for example, advantages in that it permits the electrical insulation layer to be formed in a defined fashion in the first trench. The connection region can already be produced on the side wall of the semiconductor body before the semiconductor modules are individuated. The production of the connection region with defined dimensions does not require any complex lithography for performing structuring on the side wall of the semiconductor body. The contamination risk with the electrically conductive material of the connection region in the process chambers, for example during the production of the separating trenches, is virtually eliminated by virtue of the structure of the electrically conductive material being embedded in the electrical insulation layer.
It is a development if the first trench is generated with a depth T1, and the separating trench is generated with a depth T2 extending into the semiconductor body, wherein T2≧T1. As a result, for example, the connection region can be formed over as large an area as possible and the later individuation of the semiconductor body to form semiconductor modules is easier.
One embodiment of the method provides that the first trench is produced in two parts, wherein a first trench part is narrower than the second trench part. As a result, it is possible, for example, for the side wall of the semiconductor body to be provided with the insulation layer over a large area. In particular, if the first trench part is produced extending deeper into the semiconductor body than the second trench part, advantageous side wall insulation of the semiconductor body can be produced.
An exemplary embodiment for producing a two-part first trench is also disclosed. A mask layer is formed on the first surface of the semiconductor body. A mask opening with a first width is formed in the mask layer. The semiconductor body is etched under the mask opening. The first mask opening is wide and to form a mask opening with a second width. The semiconductor body under the widened mask opening is attached such that the first and second trench parts are produced.
In particular, if the first trench part is filled completely by the electrical insulation layer and/or the side wall, oriented toward the separating trench, of the first trench part and the side wall, oriented toward the separating trench, of the second trench part form a planar side wall of the first trench, the side wall insulation of the semiconductor body, which is mentioned by way of example, can be produced particularly easily and reliably.
It is a further development of the method if at least two first trenches are produced in the semiconductor body, wherein the separating trench is produced between two of these first trenches. This measure makes it possible to produce, for example, a plurality of semiconductor modules with a connection region on the side wall in a particularly easy way. In particular, this also applies to the embodiment in which a first trench adjoins each of two opposite side walls of the separating trench.
In a further embodiment of the method there is provision that the electrical insulation layer is formed at least on the side wall, facing away from the separating trench, of the first trench, and on the bottom of the first trench with a thickness D of at least 2 μm. This may serve, for example, to minimize parasitic capacitances. This applies, in particular, if the thickness D of the electrical insulation layer is greater than 10 μm.
One further development of the invention provides that the exposed electrically conductive material is coated with an electrically conductive protective layer. This measure makes it possible to protect, for example, the electrically conductive material against environmental influences.
One exemplary embodiment provides that the exposed electrically conductive material and/or, if present, the electrically conductive protective layer is suitable for being wetted by a solder. This may be advantageous, for example, for the formation of contact with the connection region.
It is a further embodiment of the method if the electrically conductive material forms an electrically conductive layer which extends from the first trench to at least one contact region for the semiconductor body, wherein the contact region is located on the first surface of the semiconductor body, at a lateral distance from the first trench. This makes it possible, for example, for contact to be made with active semiconductor regions in the semiconductor body via the connection region on the side wall.
One embodiment provides that an electrically conductive contact element is formed between the electrically conductive material and the semiconductor body in the contact region, with the result that an electrical connection is produced between the semiconductor body and the electrically conductive material.
It is a further development of the method if the semiconductor body is provided with a further electrical insulation layer in the semiconductor body, wherein the further electrical insulation layer is formed parallel to the first surface of the semiconductor body. In particular, if the at least one first trench is produced extending as far as the further electrical insulation layer in the semiconductor body, the later semiconductor module may comprise, for example, a semiconductor body having an electrical insulation layer which is formed in a coherent fashion both on the bottom and on the side walls.
It is an exemplary embodiment of a method for producing a semiconductor module having a connection region on a side wall of the semiconductor module if the connection region is produced on the side wall of the semiconductor module according to a method as claimed in the previously specified exemplary embodiments, wherein the separating trench is produced extending from a surface of the semiconductor body as far as an opposite surface of the semiconductor body. This may be used for directly individuating the semiconductor body to form semiconductor modules. Alternatively, the separating trench can be produced extending from the first surface of the semiconductor body into the semiconductor body, and at least part of the semiconductor body on a second surface, which is located opposite the first surface, can be removed as far as the separating trench. To do this, for example a trench can be produced on the second surface of the semiconductor body, extending as far as the separating trench. However, the semiconductor body can also be thinned over the entire second surface until the second surface of the semiconductor body reaches the separating trench.
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:
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Exemplary embodiments of the invention are explained in more detail below with reference to the appended figures. However, the invention is not restricted to the specifically described embodiments but rather can be modified and refined in a suitable way. The scope of the invention includes combining individual features and feature combinations of one embodiment with feature and feature combinations of another embodiment in a suitable manner in order to arrive at further inventive embodiments.
Before the exemplary embodiments of the present invention are explained in more detail below with reference to the figures, it is to be noted that identical elements in the figures are provided with the same or similar reference symbols, and that a repeated description of these elements will not be given. In addition, the figures are not necessarily to scale, the emphasis is rather on the explanation of the basic principle.
a illustrates a semiconductor body 10 which is provided as the starting material for the rest of the method. The semiconductor body 10 may be produced, for example, from monocrystalline silicon, silicon carbide, gallium nitride, gallium arsenide or some other semiconductive material. The semiconductor body is generally embodied in the form of a plate with a first surface 11 and a second surface which is located opposite the first surface 11. The semiconductor body 10 may be a wafer in its original form. In further production steps this wafer can later also be cut up into small semiconductor modules (chips).
In the semiconductor body 10, at least a first trench 12 is produced on the first surface 11, extending into the semiconductor body 10. The first trench 12 may be produced extending into the semiconductor body 10 here using, for example, an etching process, in particular using a dry chemical etching process. The at least one first trench 12 may be produced in a first semiconductor body region 10a for a first semiconductor module.
An electrical insulation layer 15, which only partially fills the first trench 12, is formed at least on the side walls 13a and 13b and on the bottom 14 of the first trench 12. This electrical insulation layer 15 may be, for example, deposited or produced thermally. The electrical insulation layer 15 may be produced in a defined fashion with a thickness D correspondingly both on the side walls 13a and 13b and on the floor 14 with a deposition method, for example an SA-BPSG (Sub-Atmospheric Boron Phosphorus Silicate Glass) deposition. It is also possible to perform thermal oxidation of the semiconductor body 10 in order to form, for example, SiO2 as an insulation layer 15. The thickness D of the electrical insulation layer 15 can be selected in such a way that parasitic capacitances are minimized. It is therefore recommended to have electrical insulation layers with thicknesses D which are larger than 2 μm, in particular D larger than 10 μm. For this purpose, when forming the first trench 12, it is necessary to ensure that there is a sufficient width B>2D and a sufficient depth T>D of the first trench 12.
Subsequently, the remaining, still unfilled part of the first trench 12 is filled with an electrically conductive material 16. For example a metal, which is, for example, deposited galvanically, can be used as the electrically conductive material 16. For the formation of contact later it may be advantageous if the electrically conductive material 16 can be wetted by a solder. In particular, copper is a suitable electrically conductive material 16 which can be used as the connection face of the finished semiconductor module.
b illustrates a separating trench 17 produced extending along the first trench 12 and into the semiconductor body 10. The separating trench 17 is produced here in such a way that the side wall 13b of the first trench 12 directly adjoins the separating trench 17. This is done, for example, by selective etching of the semiconductor material of the semiconductor body 10, during which etching the electrical insulation layer 15 remains as a result of the selectivity of the etching. As a result, the part of the electrical insulation layer 15 which adjoins the separating trench 17 is exposed. A dry chemical etching process can be used, for example, as the etching method.
c illustrates an embodiment after the electrical insulation layer 15 which is exposed at the separating trench 17 has been removed at least to such an extent that the electrically conductive material 16 at the separating trench 17 is at least partially exposed. The removal of the electrical insulation layer 15 can also be carried out selectively with respect to the semiconductor material of the semiconductor body 10 and selectively with respect to the electrically conductive material 16 by, for example, wet chemical etching. The now exposed, electrically conductive material can optionally be coated with an electrically conductive protective layer to protect it against corrosion or other environmental influences. For example, this protective layer can be composed of NiP—AuPd which can be applied, for example in an electroless fashion, to copper. The protective layer should preferably also be capable of being wetted by a solder in order to facilitate the formation of contact later.
a illustrates a further development of the method in which, instead of a first trench 12, at least two first trenches 12′ and 12″ are produced in the semiconductor body 10. In this context, a first trench 12′ is produced in a first semiconductor body region 10a for a first semiconductor body module, and another first trench 12″ is produced in a second semiconductor body region 10b for a second semiconductor module, each extending with a depth T1 into the semiconductor body 10. The separating trench 17 is produced between two of these first trenches 12 with a depth T2 such that the separating trench 17 adjoins both first trenches 12. As a result, on one side of the separating trench 17 part of the electrical insulation layer 15 on the side wall 13b of the one first trench 12′ is exposed, and on the opposite side of the separating trench 17 part of the electrical insulation layer 15 on the side wall 13b of the other first trench 12″ is exposed. In the present case, the separating trench 17 is made deeper than the first trenches 12′ and 12″. However, said separating trench 17 can also be produced to have a smaller depth than a first trench 12 or the same depth as the first trench 12.
After, as illustrated in
a illustrates a further development of the method in which the first trench 12 has been produced in two parts. A first trench part 12a with a width b1 is made narrower here than the second trench part 12b with the width b2. In the illustrated embodiment, the first trench part 12a is also produced extending deeper into the semiconductor body 10 than the second trench part 12b. In the exemplary embodiment, the side wall 13b of each of the two illustrated first trenches 12′ and 12″, which are located opposite one another and are separated from one another by part of the semiconductor body 10, is formed without a step. This structure is produced if, for example, the part of the side wall 13b which is formed by the first trench part 12a and the part of the side wall 13b which is formed by the second trench part 12b merge with one another without an offset.
A first trench 12 which is divided into two may be produced, for example, as follows: at first, a mask layer is produced on the first surface 11 of the semiconductor body 10. Then, at least a first mask opening with a first width b1 is produced in the mask layer. The semiconductor body 10 is subsequently etched under this first mask opening, as a result of which a trench with a first width b1 comes about in the semiconductor body 10. After this, the first mask opening is widened to form a second mask opening with a second width b2. The semiconductor body 10 is then etched again under the widened second mask opening, as a result of which the trench which is firstly produced under the first mask opening is etched further and the newly added further trench with a width b2>b1 in the semiconductor body 10 forms the first and second trench parts 12a and 12b.
As illustrated in
c illustrates the result after the individuation process of the semiconductor body 10 into semiconductor modules 30 and 31. A semiconductor module 30 or 31 respectively comprises a semiconductor body region 10a or 10b. The individuation of the semiconductor body 10 into the semiconductor body regions 10a and 10b is done, for example, by means of a thinning process of the semiconductor body 10 on the second surface 20 as far as the separating trench 17. As soon as the thinning which takes place on the second surface 20 has progressed as far as the separating trench, the initially coherent semiconductor body 10 is individuated into the semiconductor body regions 10a and 10b. The thinning process can occur only locally in the region of the separating trench 17 on the second surface 10, for example as a result of trench formation on the second surface as far as the separating trench 17. However, said thinning process can also occur over the entire second surface 20, for example by grinding, polishing, etching the semiconductor body 10, and combinations thereof.
a shows the initial situation of an exemplary embodiment of the method for producing a connection region on a side wall of the semiconductor body. A passivation layer 40 is applied to the silicon semiconductor body 10 over the entire first surface 11, which passivation layer 40 can also be composed of a plurality of component layers 41 and 42, for example a silicon oxide layer (SiO2) and a nitride layer applied thereto.
As is illustrated in
c shows the situation after the exposed passivation layer 40 has been removed in the opening 44, for example by means of an etching process. Part of the first surface 11 of the semiconductor body 10 is then exposed within the opening 44.
After the first resist mask 43 has been completely removed as shown in
In a subsequent anisotropic etching process trenches 48′, 48″ are etched with a depth t1 into the semiconductor body 10, as shown in
g shows the continuation of the method in which the edge regions 40a and 40b of the passivation layer 40 which are open on the semiconductor body 10 have been removed. As a result, the parts 11c and 11d of the surface 11 of the semiconductor body 10 which are located under these edge regions 40a and 40b and the trenches 48′, 48″ are now not covered by the resist mask and are exposed in the openings 46, 47.
As is illustrated in
i shows the semiconductor body 10 with the first trenches 12′, 12″ which are formed therein and are divided into two. On the surface 11 of the semiconductor body 10 there is still the remaining part of the passivation layer 40, while the resist mask 45 has been completely removed. The surface 11 of the part 10z of the semiconductor body 10 which is located between the two first trenches 12′, 12″ is therefore not covered.
As shown in
k shows the continuation of the method, wherein a further resist mask 49 is produced on the electrical insulation layer 15. The further resist mask 49 is structured in a lithography step in such a way that openings are formed in the further resist mask 49. An opening 50 of the resist mask 49 is arranged over the part 10z of the semiconductor body 10 which is located between the first trenches 12 and in which the separating trench is formed in a later method step. The opening 50 is formed here with such a width that the electrical insulation layer 15 is completely exposed over the part 10z of the semiconductor body 10. A further opening 51 in the resist mask 49 is arranged over the region of the semiconductor body 10 which is still covered with the passivation layer 40. The further opening 51 exposes here a part of the electrical insulation layer 15 on the passivation layer 40, in particular on the top component layer 42 of the assembled passivation layer 40.
As is illustrated in
After the further resist mask 49 has been removed again, as shown in
As is shown in
As illustrated in
q shows the structured, electrically conductive layer 56 on the semiconductor body 10 after the mask 53 has been removed. The surface 11 of the part 10z of the semiconductor body 10 between the two first trenches 12′, 12″ is therefore exposed again.
As illustrated in
As is shown in
t shows the method step in which the electrical insulation layer 15 on the side walls 13b of the first trenches 12′, 12″ is removed. The removal of the electrical insulation layer 15 is carried out, for example, by wet chemical etching of the electrical insulation material 15 in the separating trench 17. The wet chemical etching can be carried out along the side walls 13b in a uniform fashion until the electrically conductive layer 56 is reached. The etching ends at this electrically conductive layer 56. The electrically conductive layer 56 is therefore exposed in the separating trench 17.
As is shown in
v shows a variant in which the exposed, electrically conductive layer 56 is still covered with an electrically conductive protective layer 61. This electrically conductive protective layer 61 is produced, for example, as a single layer or as multiple layers. The protective layer 61 has, for example, nickel phosphorus NiP and/or gold palladium AuPd.
In one exemplary embodiment as illustrated in
While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.
Number | Name | Date | Kind |
---|---|---|---|
5606198 | Ono et al. | Feb 1997 | A |
5682062 | Gaul | Oct 1997 | A |
6225207 | Parikh | May 2001 | B1 |
6300224 | Arima et al. | Oct 2001 | B1 |
6611050 | Ference et al. | Aug 2003 | B1 |
7375434 | Gross | May 2008 | B2 |
7378741 | Mauder | May 2008 | B2 |
7407852 | Su et al. | Aug 2008 | B2 |
7591071 | Ibe et al. | Sep 2009 | B2 |
7663222 | Lohninger et al. | Feb 2010 | B2 |
7665201 | Sjoedin | Feb 2010 | B2 |
8158520 | Ning | Apr 2012 | B2 |
20050029668 | Poo et al. | Feb 2005 | A1 |
20060073979 | Thieme et al. | Apr 2006 | A1 |
20060076689 | Rhodes | Apr 2006 | A1 |
20060228880 | McDaniel et al. | Oct 2006 | A1 |
20070015327 | Su | Jan 2007 | A1 |
20070148792 | Marx et al. | Jun 2007 | A1 |
20090188553 | Dubin | Jul 2009 | A1 |
20090250749 | Park | Oct 2009 | A1 |
Number | Date | Country |
---|---|---|
103 51 028 | Jun 2005 | DE |
10 2005 004 160 | Aug 2006 | DE |
Number | Date | Country | |
---|---|---|---|
20120289047 A1 | Nov 2012 | US |