DE102006045126B4 - Method for producing a connection electrode for two semiconductor zones arranged one above the other - Google Patents

Abstract

A method for producing a connection electrode for a first semiconductor zone (11) and a second semiconductor zone (12), which are arranged on top of one another and doped complementarily to one another, comprising the method steps: producing a trench (15) which extends through the first semiconductor zone ( 11) extends into the second semiconductor zone (12), so that the first semiconductor zone is exposed on side walls (151) of the trench and the second semiconductor zone (12) is exposed at least on a bottom (152) of the trench, - application of a protective layer (31; 41) onto the side walls (151) of the trench (15) in such a way that the second semiconductor zone (12) is exposed at the bottom (152) of the trench (15), - production of a first connection zone (16) in the second semiconductor zone (12) by adding dopant atoms be introduced into the second semiconductor zone (12) via the bottom (152) of the trench (15), the connection zone (16) of the same conductivity type as the second semiconductor zone (12), but with a higher density rt, - depositing an electrode layer (34) at least on the ...

Description

The present invention relates to a method for producing a connection electrode for two semiconductor zones which are arranged one above the other and complementarily doped one another, in particular a connection electrode for a source zone and a body zone of a power MOSFET.

In order to avoid negative effects of a parasitic bipolar transistor, which is formed in a power MOSFET by the sequence of the drain or drift zone, the body zone and the source zone, it is known in power MOSFET the body zone and short circuit the source zone. For this purpose, a source electrode connected to the source zone is realized in such a way that it also contacts the body zone, thereby short-circuiting the source and body zones.

In so-called trench MOSFETs, in which the body zone and the source region are arranged one above the other in a semiconductor body and in which gate electrodes are arranged in trenches which extend through the source zone and the body zone, it is It is known to arrange such a connection electrode in a trench which extends into the semiconductor region (mesa region) between two gate trenches through the source zone into the body zone. Such a realized in a trench connection contact is for example in the US 2003/0186507 A1 described.

The contribution of the contact resistance between the connection electrode and the contacted semiconductor region to the on-resistance of the component should be as small as possible. This connection electrode should therefore be manufactured so that the lowest possible contact resistance is present. This problem is exacerbated by increasing density of integration. Because with increasing integration density reduces the available for the realization of such a contact area with the result that the current density of a current flowing through these contacts increases. In order to maintain or even reduce a given total resistance, the specific contact resistance must decrease with increasing miniaturization of the device.

In order to realize a low contact resistance, highly doped connection zones are required in the areas in which the connection electrode contacts the semiconductor zones. Especially in the case of trench transistors, however, these connection zones may only have a small extent in the lateral direction, since otherwise they may influence the switching behavior of the transistor. If, for example, dopant atoms are obtained in the production of these highly doped connection zones up to the region in which an inversion channel is formed in the body zone when the component is driven, this can influence the threshold voltage of the component.

The above US 2003/0186507 A1 describes a method for producing such a source electrode and a body zone of a power MOSFET contacting terminal electrode. In this method, it is provided to produce by means of an implantation method a highly doped first connection zone in a region of the source zone which is spaced apart from the trenches with the gate electrodes arranged therein. Subsequently, a trench is generated, which extends through this highly doped connection zone into the body zone, wherein in the area of side walls of this trench remain sections of the heavily doped first connection zone. After this trench has been produced, a second heavily doped connection zone is produced below the trench bottom in the body zone by means of an implantation method, and the trench is then filled up with an electrode material. The dopant atoms, which are implanted for the production of the first and second terminal zones, are in this case of a mutually complementary conductivity type.

In the case of this known method, when the second heavily doped connection zone is produced in the body zone, dopant atoms can also be implanted into the source zone via the side walls of the trench. This can lead to a reduction in the net doping in the region of the first connection zone and thus to an increase in the contact resistance between the subsequently produced connection electrode and the source zone.

The DE 10 2004 057 237 A1 describes a method of making a buried body region contact of a MOS transistor, in which a trench for the terminal contact is etched using an oxide spacer as a mask.

The object of the present invention is to provide a method for producing a connection electrode for a first and a second semiconductor zone, which are arranged one above another and doped complementary to one another, which ensures a low contact resistance between the connection electrode and the two contacted semiconductor zones avoids the above-mentioned disadvantages.

This object is achieved by a method according to claim 1, a method according to claim 13 and a method according to claim 17. Advantageous embodiments of the invention are the subject of the dependent claims.

In one of the inventive method for producing a connection electrode for a first semiconductor zone and a second semiconductor zone, which are arranged one above the other and are doped complementary to one another, it is provided to first produce a trench which extends through the first semiconductor zone into the second semiconductor zone the first semiconductor region is exposed on sidewalls of the trench and the second semiconductor region is exposed at least at a bottom of the trench. Subsequently, a protective layer is applied to one of the first and second semiconductor zones in the trench and in the other, not covered by the protective layer semiconductor zone, a first connection zone is prepared. This connection zone is produced by introducing dopant atoms via the trench into this other semiconductor zone. These dopant atoms are in this case selected so that a first connection zone is formed which is doped with the same conductivity type as this semiconductor zone, which is not covered by the protective layer, but is doped higher. Subsequently, an electrode layer is applied to the sidewalls and bottom of the trench to make the terminal electrode.

The object of the protective layer in this method, which covers the protective layer covered one of the two semiconductor zone, which is hereinafter referred to as a protected semiconductor zone, to protect against doping by the dopant atoms, for the production of the first connection zone via the trench in the other of the two Semiconductor zones, hereinafter referred to as unprotected semiconductor zone, are introduced. It is therefore desirable to prevent the introduction of these dopant atoms into the protected semiconductor region because the dopant atoms used to form the first junction region in the unprotected semiconductor region are dopant atoms that produce a semiconductor region of a conductivity type complementary to the protected semiconductor region. These dopant atoms would thus reduce the net doping of the protected semiconductor region in the region of the trench and thus reduce the contact resistance between the later-made terminal electrode and this protected semiconductor region.

The protective layer itself may in this method be a layer containing dopant atoms, wherein these dopant atoms are dopant atoms which generate a semiconductor zone of the same conductivity type as the protected semiconductor zone. The dopant atoms from this protective layer are diffused into the protected semiconductor zone by heating at least this protected semiconductor zone for a predetermined period of time to a predetermined diffusion temperature. This results in the protected semiconductor zone, a second connection zone, which is of the same conductivity type as the protected semiconductor zone itself. The temperature during the temperature process and its duration are dependent on the type of dopant atoms used. Such diffusion processes are well known, so that it is possible to dispense with further explanations.

The production of the first connection zone takes place, for example, by implantation of dopant atoms via the trench into the unprotected, d. H. the semiconductor layer not covered by the protective layer. Subsequent to implantation of the dopant atoms, a temperature step is known to be required by which the implanted region is heated to a predetermined temperature for a predetermined period of time to anneal radiation damage caused by the implantation and to activate the implanted dopant atoms, i. H. to incorporate into the crystal lattice of the semiconductor material used. This temperature step for activating the implanted dopant atoms can be used simultaneously as a temperature step for the diffusion of the dopant atoms out of the protective layer into the protected semiconductor zone. However, depending on the type of dopant atoms present in the protective layer and, depending on the type of implanted dopant atoms, it may also be necessary to carry out a thermal step prior to the implantation of the dopant atoms for the production of the first terminal zone, in order partially already in the protected semiconductor zone dopant atoms from the protective layer diffuse.

The protective layer with the dopant atoms present therein can consist of an electrically conductive material, such as, for example, doped polysilicon, or of a dielectric material, such as, for example, arsenic-silicate glass (ASG), phosphosilicate glass (PSG) or boron-silicate glass. The type of doping of the polysilicon or the selection of one of the previously explained glass materials is dependent on whether a p-doped or an n-doped second junction zone is to be produced by the diffusion process.

An electrically conductive protective layer may in this case remain in the trench before the connection electrode is produced, while a dielectric, d. H. electrically insulating, protective layer after preparation of the first and second connection zones and before the preparation of the connection electrode must be removed.

As a protective layer is also a metal, such as titanium, which has no doping effect, which, however, enters a metal-semiconductor compound with the surrounding semiconductor material when carrying out the temperature step, and thus provides a low-resistance terminal contact. When using Silicon as a semiconductor material for the two semiconductor zones is formed when using a metallic protective layer in the transition region between this protective layer and the semiconductor material of the protected semiconductor zone, a silicide, which provides a low-resistance terminal contact. A suitable material for the protective layer is, for example, titanium.

The protective layer can be applied to the first semiconductor zone in the region of the side walls of the trench or to the second semiconductor zone in the region of the trench bottom.

The first terminal zone in the unprotected semiconductor zone not covered by the protective layer can also be produced by means of a diffusion method by applying a dopant-containing layer in the trench at least to the unprotected semiconductor zone and by diffusing dopant atoms from this layer into the unprotected semiconductor zone by means of a temperature process become. In this case, the trench is preferably completely filled up with the material containing the dopant atoms.

An alternative to the method explained above is to produce the trench for the production of the connection electrode in two stages. In a first step, the trench is made to a first depth that is less than the ultimate trench depth desired. After this first step, a first junction zone is formed in the first semiconductor zone exposed on sidewalls of this trench. The production of this first connection zone takes place, for example, by implantation of dopant atoms over the side walls of this first trench. The depth of this first trench can be chosen such that the first trench ends within this first semiconductor zone, but the trench can already extend into the second semiconductor zone.

After the first trench section has been produced, the trench is extended from its bottom in the direction of the second semiconductor zone. Subsequently, dopant atoms are introduced into the second semiconductor zone via the bottom of the extended trench in order to generate a second connection zone there. During the production of the first connection zone in the first semiconductor zone, the region of the second semiconductor zone in which the second connection zone is to be generated is protected by the semiconductor section from doping, which is removed when the trench is extended in the direction of the second semiconductor zone.

In a further alternative of the method according to the invention, after production of the trench, it is intended to produce the first connection zone in the first semiconductor zone and the second connection zone in the second semiconductor zone by implantation of dopant atoms, wherein these implantation steps take place at different implantation angles, which are selected such that at Producing the first connection zone in the first semiconductor zone portions of the second semiconductor zone remain spared by a doping, and that remain in the production of the second connection zone in the second semiconductor zone portions of the first semiconductor zone of a doping. The production of the first connection zone in the first semiconductor zone, which is exposed on sidewalls of the trench, takes place, for example, by implantation of dopant atoms at a first implantation angle, which is chosen so that the dopant atoms do not reach the bottom of the trench. The production of the second connection zone takes place, for example, by implanting dopant atoms at an angle of 0 ° with respect to the sidewalls of the trench, so that in this implantation step only dopant atoms are implanted into the second semiconductor zone via the bottom of the trench.

All three methods explained above for producing a connection electrode, which each comprise method steps for producing at least one heavily doped connection zone, have in common that, when the at least one connection zone is produced in one of the two semiconductor zones, the other of the two semiconductor zones is protected from doping. This protection can be achieved by applying a protective layer, by firstly existing semiconductor sections which are removed later in the course of the process, or by suitable adjustment of the implantation angle during the implantation of dopant atoms.

The present invention will be explained in more detail with reference to figures.

1 1 illustrates, on the basis of cross-sectional representations of a semiconductor body having a first and a second semiconductor zone, a first exemplary embodiment of a method according to the invention for producing a connection electrode, in which a protective layer is applied to one of the two semiconductor zones which remains on the respective semiconductor zone.

2 shows a cross-sectional view of a semiconductor device, by a comparison with the method 1 modified method has been made, in which the protective layer is removed.

3 illustrates cross-sectional views of a semiconductor body during various process steps a second Embodiment of a method for producing a connection electrode, in which a protective layer is applied to one of the two semiconductor zones.

4 1 illustrates, by means of cross-sectional representations of a semiconductor body, a third exemplary embodiment of a method for producing a connection electrode, in which the protective layer is applied to one of the two semiconductor zones to be contacted.

5 1 illustrates a cross-sectional representation of a semiconductor body having a first and a second semiconductor zone to be contacted, a method for producing a connection electrode, in which a trench for the connection electrode is produced in two stages.

6 3 illustrates cross-sectional representations of a semiconductor body having first and second semiconductor zones to be contacted, a method for producing a connection electrode for these two semiconductor zones, in which connection zones in the two semiconductor zones are produced by implantation steps using different implantation angles.

7 3 illustrates, by means of cross-sectional representations of a semiconductor body, a method for producing the trench for the connection electrode using a spacer produced by oxidation.

8th illustrates another method for making a connection zone.

9 FIG. 4 illustrates a modification of a method step of FIG 8th explained method.

In the figures, unless otherwise indicated, like reference numerals designate like component portions with the same meaning.

The methods according to the invention are explained below for the production of a connection electrode which contacts a source zone and a body zone of a power MOSFET or power IGBT and thereby short-circuits these component zones. However, the methods according to the invention are not limited to this application but are applicable to the production of connection electrodes for arbitrary components which have two semiconductor zones arranged one above the other and complementary to one another.

A first exemplary embodiment of a method according to the invention for producing a connection electrode which contacts two semiconductor zones doped complementary to one another, in which a protective layer is applied to one of the semiconductor zones during the method sequence, will be described below with reference to FIG 1 explained.

1a shows a side view of a cross section through a semiconductor body 100 in which a device structure for a power MOSFET is provided. This device structure comprises a first semiconductor zone 11 in the area of a front 101 the semiconductor body is arranged, and in a vertical direction to this first semiconductor zone 11 subsequent second semiconductor zone 12 that is complementary to the first semiconductor zone 11 is doped. The first semiconductor zone 11 forms in a MOSFET or IGBT whose source zone, the second semiconductor zone 12 forms in a MOSFET or IGBT its body zone. The source zone 11 is n-doped in an n-channel MOSFET, p-doped in a p-channel MOSFET, and usually n-doped in an IGBT. The body zone 12 is in each case complementary to the source zone 11 doped.

The second semiconductor zone 12 is above a third semiconductor zone 13 arranged at a MOSFET and IGBT whose drift zone 13 forms and each complementary to the second semiconductor zone 12 is doped. To this third semiconductor zone 13 closes towards one of the front 101 opposite back 102 of the semiconductor body 100 a heavily doped connection zone 14 which forms the drain zone of the MOSFET or IGBT and those in a MOSFET of the same conductivity type as the drift zone 13 and in an IGBT complementary to the drift zone 13 is doped. This drain zone 14 can - as in 1a shown in dashed lines - be present before the preparation of the connection electrode to be explained yet. This connection zone 14 For example, it may be in heavily doped semiconductor substrate onto which the drift zone 13 , the body zone 12 and the source zone 11 are applied by means of an epitaxial process. The drain zone 14 However, for example, by means of an implantation method in which the dopant atoms on the back 102 in the semiconductor body 100 can be implanted after preparation of the terminal electrode or while still to be explained implantation steps in producing the terminal electrode.

A gate electrode, of which in 1a two electrode sections 21 are shown extends in the vertical direction, starting from the first semiconductor zone 11 through the second semiconductor zone 12 to the third semiconductor zone 13 and is by means of a dielectric 22 opposite the semiconductor zones 11 . 12 . 13 of the semiconductor body 100 isolated. Towards the front 101 For example, the gate electrode is preferably of a thicker dielectric layer 23 covered, which also partially over the first semiconductor zone 11 above the front 101 of the semiconductor body. In this context, it should be noted that the representation of the layer thicknesses in the figures are not to scale. In particular, it can be over the first semiconductor zone 11 extending portion of the insulating layer also be made thicker than shown.

The aim of the method according to the invention is to produce a connection electrode which comprises the first and second semiconductor zones 11 . 12 contacted with low resistance, but in their preparation, the doping concentrations of the first and second semiconductor zone 11 . 12 in a directly to the gate dielectric 22 subsequent area is not changed, since this would lead to a change in the electrical properties of the trench MOSFET, in particular to a shift in the threshold voltage.

In first process steps, the result in 1b is shown, a trench 15 in the mesa area between two trenches with gate electrode sections arranged therein 21 produced by the dielectric layer 23 and the first semiconductor zone 11 to the second semiconductor zone 12 extends. This ditch 15 is laterally spaced from the trenches with the gate electrode sections 21 arranged. It should be noted that the production of the connection electrode is explained below only with reference to an electrode section which is arranged between two trenches with gate electrode sections arranged therein. In a power MOSFET comprising a cell array having a plurality of spaced-apart gate electrode sections 21 Preferably, such terminal electrodes will be in each mesa area between two gate electrode sections 21 produced.

The ditch 15 has side walls 151 and a floor 152 on. The first semiconductor zone 11 lies after making this trench 15 on the side walls 151 free. The second semiconductor zone 12 lies at the bottom of the ditch 152 and in sections also on the side walls of the trench 151 free because of the ditch 15 starting from the first page 101 to below the interface between the first and second semiconductor zone 11 . 12 extends. The making of the trench 15 for example, by means of a well-known anisotropic etching process using a mask that leaves free the region of the trench during the etching process.

In next process steps, which are in the 1c and 1d are illustrated in the trench 15 a protective layer 31 manufactured, which is one of the two first and second semiconductor zones 11 . 12 completely covered within the trench. Referring to 1c becomes a protective layer 31 ' deposited over the entire surface, the front 101 of the semiconductor body 100 , as well as the side walls 151 and the floor 152 of the trench 15 covered. The deposition of this protective layer 31 ' can be done for example by means of a CVD method (CVD = chemical vapor deposition).

In next process steps, the result in 1d is shown, this protective layer is at least from the ground 152 of the trench 15 removed, leaving a protective layer 31 on the side walls 151 of the trench 15 arises within the trench the first semiconductor zone 11 completely covered. The protective layer 31 partially covers the second semiconductor zone as well 12 on the sidewalls of the trench, however, leaves the second semiconductor zone 12 at the bottom of the ditch 52 free. The production of this protective layer 31 on the side walls 152 the trench is made, for example, by anisotropic etching back of the protective layer 31 ' , In this anisotropic etching process, the protective layer becomes 31 ' both above the front 101 of the semiconductor body as well as the bottom of the trench 152 away.

During next process steps, which are in 1e are illustrated, a first connection zone 16 below the trench bottom 152 in the second semiconductor zone 12 generated. This first connection zone 16 is of the same conductivity type as the second semiconductor zone 12 , but higher doped. For the following explanation it is assumed that the first semiconductor zone 11 doped with dopant atoms of a first conductivity type, which are hereinafter referred to as dopant atoms of the first type, and that the second semiconductor zone 12 doped with dopant atoms of a second conductivity type complementary to the first conductivity type, hereinafter referred to as dopant atoms of the second type.

For making the first connection zone 16 become dopant atoms of the second type on the ground 152 of the trench 15 in the second semiconductor zone 12 implanted. The above the gate electrode 21 arranged thicker dielectric layer in sections, also above the first semiconductor zone 11 is arranged and extends in a lateral direction to the ditch 15 extends, protects during this implantation step 16 the first semiconductor zone 11 in the area below the front 101 before implantation with dopants of the second type. Inside the trench 15 protects the protective layer 31 at the trench sidewalls 151 the first Semiconductor zone 11 before doping with dopant atoms of this second type.

Preferably, before carrying out the implantation step, a scattering oxide 32 on the ditch floor 152 applied, but in particular can be deposited over the entire surface. This litter oxide 32 serves to scatter the for the production of the first connection zone 16 implanted dopant atoms.

The protective layer 31 In the example shown, it is a layer doped with dopant atoms of the first type. When carrying out a temperature process in which the semiconductor body 100 at least in the region of the first semiconductor zone 11 is heated to a predetermined diffusion temperature for a predetermined period of time, diffusing these dopant atoms of the first type of the protective layer 31 in the first semiconductor zone 11 and create there a second connection zone 17 , which are of the same conductivity type as the first semiconductor zone 11 is, but is more highly doped. The temperature of this diffusion process is between 800 ° C and 1100 ° C for a duration between 10 seconds and 15 minutes. The duration depends among other things on the choice of dopant. For example, while boron and phosphorus diffuse comparatively rapidly, so that a shorter diffusion period is set, arsenic diffuses comparatively slowly and requires longer diffusion times.

For making the first connection zone 16 After implantation of the dopant atoms of the first type, a temperature step is also required to heal radiation damage and to activate the implanted dopant atoms, that is, into the crystal lattice of the semiconductor body 100 install. Depending on which elements are used as dopant atoms of the first type and as dopant atoms of the second type, a single temperature step may be sufficient to activate both the implanted dopant atoms of the second type and the dopant atoms of the first type from the protective layer 31 in the first semiconductor zone 11 diffuse. Provided that the diffusion temperature of the dopant atoms of the first type, which for the production of the second connection zone 17 If it is intended to be higher than the activation temperature required for the activation of the dopant atoms of the second type, it is possible to perform a temperature step before implantation of the dopant atoms of the second type, through which the dopant atoms of the first type into the first semiconductor zone 11 be implanted. Only then are the dopant atoms of the second type implanted and activated by means of a further temperature step to the second connection zone 16 manufacture. The activation temperatures are in the range of the above-mentioned diffusion temperatures (800 ° C to 1100 ° C). The activation periods may be in the range of the diffusion times mentioned above (15 seconds to 15 minutes).

The protective layer 31 with the dopant atoms of the first type contained therein may be an electrically conductive layer, such as doped polysilicon, but may also be an electrically insulating layer, such as a silicate glass. For producing an n-doped second connection zone 17 is suitable, for example, polysilicon doped with arsenic or phosphorus, or phosphorus silicate glass (PSG) or arsenic-silicate glass (ASG). For producing a p-doped second connection zone 17 is suitable boron-doped polysilicon or boron-silicate glass (BSG) as a protective layer 31 ,

The scattering oxide layer 32 except the scattering in the trench floor 152 implanted dopant atoms also have the function of preventing, during the diffusion process, dopant atoms of the first type from the protective layer 31 get into the atmosphere prevailing in the ditch and out of this atmosphere into the ditch floor 152 diffuse where they net the doping of the first terminal zone 16 with dopant atoms of the second conductivity type and thus reduce the contact resistance between this first connection zone 16 and increase the connection electrode still to be produced.

After making the first and second connection zones 16 . 17 and before making this connection electrode 34 becomes the litter oxide layer 32 , For example, removed by means of an etching process. Provided the material of the protective layer 31 a dielectric material, such as silicate glass, this protective layer must be 31 also be removed while an electrically conductive protective layer 31 , such as doped polysilicon, may remain.

1f shows the device according to process steps for the removal of the scattering oxide 32 and for producing a connection electrode 34 , The protective layer 31 , which in the example shown an electrically conductive protective layer 31 is, remains on the side walls 151 of the trench. The production of the connection electrode 34 is done by applying an electrode layer on the sidewalls and bottom of the trench, the trench 15 preferably completely filled with electrode material. Before depositing the electrode layer, a barrier layer is preferably used 33 applied, which is electrically conductive and consists for example of titanium (Ti). This barrier layer can fulfill different functions: Thus, the barrier layer 33 in the manufacturing processes for the production of the connection electrode 34 the Protect semiconductor material in the trench from contamination. This is particularly necessary when a terminal electrode made of tungsten (W) is produced. Furthermore, the barrier layer 33 fulfill the function of a contact layer, the complementary doped connection zones 16 . 17 shorts. This contact function of the barrier layer is required, for example, when the connection electrode 34 is made of highly doped polysilicon. When the terminal electrode is made of an aluminum-copper compound, the barrier layer prevents spiking.

A barrier layer can be dispensed with if, for example, AlCu (Si) is used as the material for the connection electrode.

The result of the manufacturing method explained above is a semiconductor component having a first and a second semiconductor zone 11 . 12 , which are doped complementary to each other and through a connection electrode 34 contacted with low impedance. The low-resistance contact is made possible by the two heavily doped connection zones 16 . 17 and in the region of the first semiconductor zone 11 through the highly doped, for example made of polysilicon, protective layer 31 ,

2 shows a cross section through the device after production of the connection electrode 34 and the optional barrier layer 33 Here, the protective layer was removed on the side walls of the trench. The removal of the protective layer 31 may, for example, together with the removal of the litter oxide layer ( 32 in 1e ) respectively. Typical etching materials used to etch the scattering oxide layer 32 Silica glass which is suitable as a protective layer is usually also etched, so that the scattering oxide layer 32 and the protective layer 31 be removed in a common process step. At the in 2 The illustrated component contacts the terminal electrode, which is the optional barrier layer 33 and the electrode layer 34 comprises, in the region of the side walls of the trench, the heavily doped second connection zone 17 immediate.

Another method of manufacturing a first and second semiconductor zone 11 . 12 contacting terminal electrodes using a protective layer will be described below with reference to 3a to 3c explained.

Referring to 3a becomes in this process after production of the trench 15 a metallic protective layer 41 on the side walls 151 of the trench 15 applied. The production of this metallic protective layer 41 takes place, for example, according to the production of in 1d represented protective layer 31 by depositing a metallic layer 41 ' , in the 3a is still shown in dashed lines, and then anisotropic etching back this metallic layer 41 ' so that a protective layer 41 on the side walls 151 of the trench 15 remains.

Referring to 3b then becomes a dopant material 43 containing dopant atoms of the second type into the trench 15 brought in. This dopant-containing material 43 is for example doped polysilicon. This dopant material 43 must at least partially fill the trench, leaving the ground 152 however, this dopant material layer may also be deposited such that the trench 15 completely with dopant material 43 is filled in and that also areas of this Dotierstoffmaterialschicht 43 still above the front of the semiconductor body 101 are arranged as in 3b is shown.

After making this dopant material layer 43 a diffusion step takes place in which the semiconductor body 100 is heated to a diffusion temperature for a predetermined period of time, so that dopant atoms from the Dotierstoffmaterialschicht 43 on the ground 152 of the trench in the second semiconductor zone 12 diffuse there and there a highly doped first connection zone 16 of the second conductivity type. The protective layer 41 at the trench sidewalls 151 serves as a diffusion barrier and protects the first semiconductor zone 11 during the diffusion process before a diffusion of dopant atoms of the second conductivity type in this first semiconductor zone 11 , In the border area between the protective layer 41 and the semiconductor material is formed during the diffusion process, a metal-semiconductor compound having a low-resistance terminal contact between the metallic protective layer 41 and in particular the first semiconductor zone 11 guaranteed. When using silicon as the semiconductor material, this metal-semiconductor compound is a silicide. Titanium is particularly suitable as the material for the metallic protective layer.

After making the connection zone 16 below the trench bottom in the second semiconductor zone 12 becomes the dopant material layer 43 , For example, removed by means of an etching process. Subsequently, the connection electrode 34 by depositing an electrode material layer on the sidewalls 151 and the floor 152 of the trench 15 wherein, prior to depositing the electrode layer, optionally a barrier layer 33 at least on the ditch floor 152 and the side walls 151 the trench is applied.

The dopant material layer may be made of an electrically conductive material, such as doped polysilicon. In a manner not shown, such an electrical conductive dopant material layer at least partially remain in the trench and there fulfill the function of the connection electrode. For example, there is the possibility of such an electrically conductive dopant material layer after diffusion of the dopant atoms into the semiconductor body 100 to be etched back so far that the at least partially filled with the Dotierstoffmaterialschicht and then an electrode layer, for example made of aluminum, produce, which forms a further part of the connection electrode and the dopant material layer contacted.

Such an electrode layer can also directly, ie without previous etching process on the in 3c illustrated dopant material layer 34 be applied, provided that it consists of an electrically conductive material.

The following explained 4a to 4c show a modification of the above with reference to the 3a to 3c explained method. In this method, after making the trench 15 a metallic protective layer 42 on the ditch floor 152 applied, while the trench sidewalls remain free. The protective layer 42 For example, it consists of a silicide, such as titanium silicide or cobalt silicide. Such a protective layer can be made by highly non-conforming sputtering of a metal, such as titanium or cobalt, and a subsequent non-conforming self-aligned TiSi process. In this non-conforming deposition by sputtering, the metal is on the ground 151 of the trench 15 and on the insulation layer 23 but not on the side walls 152 of the ditch. Subsequently, a temperature process is carried out, through which the metal at the bottom of the trench 151 with the silicon of the semiconductor body 100 reacts to form a silicide and forms the protective layer there, while the metal does not react on the insulating layer. That on the insulation layer 23 remaining metal is then removed wet-chemically.

After making this protective layer 42 at the bottom of the ditch 152 becomes the ditch 15 at least up to an upper edge of the second semiconductor layer 11 but preferably completely with a dopant material layer 44 filled, the dopant atoms of the same conductivity type as the first semiconductor zone 11 , that is, dopant atoms of the first type. This dopant material layer 44 is, for example, a doped polysilicon layer. After making this dopant material layer 44 a diffusion process takes place, in which the semiconductor body is heated to a diffusion temperature for a predetermined period of time, whereby dopant atoms from the dopant material layer 44 over the side walls 152 of the trench 15 in the first semiconductor zone 11 diffuse in and there a highly doped connection zone 17 of the same conductivity type as the first semiconductor zone 11 form. The dopant atoms are, for example, phosphorus atoms or arsenic atoms, if an n-doped terminal zone 17 is to be prepared, and the dopant atoms are, for example boron atoms, when a p-doped junction zone 17 to be produced.

Upon completion of the diffusion process, the dopant material layer becomes 44 is removed and an electrode material is applied to the sidewalls and the bottom of the trench or the trench is completely filled with an electrode material, as shown in 4c is shown. Optionally, prior to deposition of the electrode layer 34 a barrier layer 33 For example, made of titanium at least applied to the side walls and the bottom of the trench.

An alternative method of manufacturing a first and a second semiconductor zone 11 . 12 contacting terminal electrode will be described below with reference to 5a to 5d explained.

Referring to 5a will first dig in this process 15 ' made through the dielectric layer 23 over the front 101 up to a first trench depth d1 in the semiconductor body 100 extends, wherein this first trench depth d1 is less than the final desired depth of the trench. This first trench section 15 ' extends in the example in 5a to the second semiconductor zone 12 in, but in a manner not shown also above this second semiconductor zone 12 in the first semiconductor zone 11 end up.

This first trench section 15 ' has side walls 151 ' and a floor 152 ' on. Referring to 5b become dopant atoms over the sidewalls 151 ' and the floor 152 ' in the first and second semiconductor zone 11 . 12 introduced to a highly doped junction region of the same conductivity type as the first semiconductor region 11 to create. For this purpose, dopant atoms of the first type become, for example, over the sidewalls 151 ' in the first semiconductor zone 11 implanted. An implantation of the dopant atoms also takes place via the soil 152 of the trench 15 ' in the second semiconductor zone 12 , The one next to the side walls 151 and the floor 152 The semiconductor region arranged in the trench with dopant atoms of the first type implanted therein is shown in FIG 5b with the reference number 17 ' designated. For the implementation of this implantation method is optionally a litter oxide 32 at least on the side walls 151 ' and the floor 152 ' of the trench 15 applied.

Instead of performing an implantation process, the doped semiconductor zone 17 ' also produced by a diffusion process by the trench section 15 ' is filled in a manner not shown with a material containing dopant atoms and then by dopant atoms of this material during a temperature step in the first and second semiconductor zone 11 . 12 be diffused.

During next procedural steps, the result in 5c is shown, the trench by means of an etching process in the direction of the second semiconductor zone 12 etched to a desired final depth d2. Unless for the basis of 5b explained process steps a litter oxide 32 was applied, this litter is initially anisotropic from the soil 152 ' of the trench section 15 ' removed while this litter oxide in a manner not shown on the side walls 151 ' of the trench section 15 ' remains. The one produced by the etching process, starting from the bottom 152 ' of the first trench section 15 ' further in the semiconductor body hineinzstreckende further trench portion has in this case a smaller width w2 than the first trench portion 15 ' which has a width w1 on.

After lengthening of the trench to its desired final depth d2, dopant atoms are transferred to the bottom 152 of the trench 15 in the second semiconductor zone 12 implanted around a heavily doped junction zone 16 of the same conductivity type as the second semiconductor zone 12 to create. After implantation of these dopant atoms, a temperature step is required in the manner already explained in order to heal radiation damage and to activate the implanted dopant atoms. To activate in the area 17 ' implanted dopant atoms of the first type and for activation of the above ground 152 In this case, a common temperature step may be sufficient for doping atoms of the second type implanted in the trench. The result is a highly doped junction zone 16 of the same conductivity type as the second semiconductor zone 12 at the bottom of the two-step trench and a heavily doped junction zone 17 of the same conductivity type as the first semiconductor zone 11 on side walls of the first trench section 15 ' of the two-step trench.

To these process steps for the preparation of the connection zones 16 . 17 join in process steps for the preparation of the connection electrode. These process steps are as a result in 5d shown. To produce the connection electrode, an electrode layer is deposited on the side walls and the bottom of the trench, as in the previously explained method, wherein the trench is preferably completely filled with electrode material. In addition, a barrier layer can optionally be added 33 on the sidewalls and bottom of the trench before depositing the electrode layer.

Based on 6a to 6c is a further alternative of a method for producing a first and second semiconductor zone 11 . 12 contacting connecting electrode explained. Referring to the 6a and 6b is provided in this method, dopant atoms of the first conductivity type via the side walls 151 of the trench 15 in the first semiconductor zone 11 and dopant atoms of the second type above the ground 152 of the trench into the second semiconductor region, thereby forming a heavily doped junction region 17 of the same conductivity type as the first semiconductor zone 11 in this semiconductor zone 11 and a heavily doped junction region of the same conductivity type as the second semiconductor region in this second semiconductor region 12 to create. To carry out these implantation steps is preferably a litter 32 at least on the side walls 151 and the bottom of the trench 152 applied.

In order to achieve that the dopant atoms of the first type for the preparation of the connection zone 17 essentially only in the first semiconductor zone 11 are introduced, an implantation angle, under which the dopant atoms are implanted, selected so that no dopant atoms up to the trench bottom 152 can reach. The upper edges of the trench 15 shield at a suitable implantation angle the trench bottom against an implantation of dopant atoms of the first type. In the case of a trench depth d and a trench width w, for the smallest angle α, under which the dopant atoms can barely be implanted relative to the vertical, in order not to reach the trench bottom: α = arctane (w / d) (1)

With provision of a scattering oxide 32 d denotes the trench depth which is still present after application of the scattering oxide, while w denotes the width of the trench after application of the scattering oxide 32 is available.

To avoid implantation of dopant atoms into the bottom of the trench, sidewall implantation is thus performed at angles less than the critical angle α given in Equation 1.

The production of the connection zone 16 below the trench bottom 152 takes place by implantation of dopant atoms at an angle of 0 ° with respect to the vertical, ie with respect to the trench sidewalls 151 , or at an angle of 90 ° relative to the trench bottom. This implant prevents dopant atoms over the side walls 151 of the trench into the first semiconductor zone 11 be implanted.

In general, in the method described above, the critical angle α - and thus the angles at which the dopant atoms of the first type for the preparation of the connection zone 17 may be implanted - the smaller the higher the aspect ratio of the trench, ie the ratio of trench width to trench depth is. While with an aspect ratio of 1: 1 the implantation angle should be between 45 ° and 60 ° to ensure that no dopant atoms are implanted into the bottom of the trench, angles of between 20 ° and 45 ° are already sufficient with an aspect ratio of 3: 1. to ensure this.

The implantation processes are followed by the process steps for the preparation of the connection electrode which have already been explained above, wherein a scattered oxide which may have been applied before this connection electrode is produced 32 Will get removed.

6c shows the device after performing the process steps for the preparation of the connection electrode 34 wherein, optionally before deposition of the electrode layer for producing the connection electrode, a barrier layer 33 at least on the side walls and the bottom of the trench 15 is applied.

A possible method of making the starting from the front 101 in the semiconductor body 100 extending into the trench 15 for the later connection electrode is described below with reference to 7a to 7e explained. 7a shows the semiconductor body 100 in side view in cross-section after performing process steps for the preparation of the gate electrodes arranged in trenches 21 and the gate electrodes 21 dielectric with respect to the semiconductor body 100 insulating gate dielectric layers 22 and after production of the second semiconductor layer 12 , This second semiconductor layer 12 is achieved, for example, by implantation of dopant atoms of the second conductivity type across the front 101 in the semiconductor body 100 and subsequently performing a temperature treatment. The first semiconductor zone 11 can in this case according to the second semiconductor zone by implantation of dopant atoms and a subsequent temperature treatment immediately after the production of the second semiconductor zone 12 can be prepared, but - as will be explained - also be produced at a later date in the process.

The gate electrodes 21 are realized in this arrangement so that an upper end of the gate electrodes 21 opposite the front 101 of the semiconductor body 100 is reset, so that each recesses 18 above the gate electrodes 21 in the semiconductor body 100 available.

Referring to 7b will the in 7a illustrated arrangement of a temperature treatment is subjected, so that near-surface portions of the semiconductor body 100 and the gate electrodes 21 oxidize, causing in the area of the front 101 both over sections of the semiconductor body 100 , in particular over the measuring areas, as well as over the gate electrodes 21 an oxide layer 24 ' arises. The gate electrodes 21 consist for example of doped polysilicon and thus oxidize approximately at the same temperatures as the semiconductor body 100 , which consists for example of silicon.

A thickness of the oxide layer is, for example, between 200 and 300 nm, for which purpose a near-surface layer of the semiconductor body having a thickness of approximately 100 to 150 nm is "consumed". The oxidation of the semiconductor body 100 takes place here both on the front 101 as well as in those areas that are lateral to the recesses 18 above the gate electrodes 21 exposed. This oxidation of the front 101 and the side walls of the recesses causes the oxide layer 24 ' above the gate electrodes 21 funnel-shaped or V-shaped runs. The oxidation layer 24 ' all over exposed areas of the semiconductor body 100 and the gate electrodes 21 grows up, due to the gaps 18 above the gate electrodes 21 thereby an uneven surface structure with recesses above the gate electrodes 21 on.

Referring to 7c gets onto the oxide layer 24 ' then a filling layer 25 ' applied to the recesses of the oxide layer 24 ' fills. This filling layer 25 ' consists for example of an insulating material, such as a deposited oxide, such as tetraethoxysilane (TEOS), or of a doped or undoped silicate glass (PSG, BPSG, USG).

This filling layer 25 ' and the oxide layer 24 ' are then removed as far as that between the trenches with the gate electrodes 21 lying measuring region of the semiconductor body 100 is revealed in the result in 7d is shown. The removal of these two layers takes place, for example, by a chemical-mechanical polishing process (CMP) or by an etching process. The oxide layer 24 ' and the filling layer 25 ' remain partially in the area of the previous recesses ( 18 in 7a ) of the semiconductor body 100 above the gate electrodes 21 , In this context, it should be noted that the filling layer 25 ' essentially serves these recesses above the gate electrodes 21 completely fill. On the deposition of this filling layer 25 ' can then be dispensed with, if a thickness of the oxide layer 24 ' is chosen so that these the recesses already up to the front 101 of the semiconductor body 100 fills up if a surface of the oxide layer 24 ' in a region above the gate electrodes 21 in the vertical direction is therefore higher than the front 101 of the semiconductor body 100 in the area of the measuring area.

After performing the ablation process remaining sections 24 . 25 the oxide layer 24 ' and the filling layer 25 ' form above the gate electrodes 21 "Stopper" made of insulation material, which faces the front 101 widen the semiconductor body. If a production of the first semiconductor zone 11 not already following the production of the second semiconductor zone 12 is done, this first semiconductor zone can be made using an implantation and temperature process following the production of the insulation plug 24 . 25 respectively.

Using these insulation plugs 24 . 25 As a mask, an etching process is then carried out, through which a trench 15 etched in the measuring area, starting from the front 101 through the first semiconductor zone 11 to the second semiconductor zone 12 extends. The etching process is an anisotropic etching process, by which the semiconductor material exclusively in the vertical direction of the semiconductor body 100 is removed. The dimensions of the trench 15 in the lateral direction are determined by the mutual distances insulation plug 24 . 25 in the lateral direction in the area of the front side 101 of the semiconductor body 100 , As the insulation plugs towards the front 101 widen the semiconductor body and thus in the lateral direction over the dimensions of the trenches with the gate electrodes arranged therein 21 go out, these insulation pegs act 24 . 25 as spacers between the pins with gate electrodes 21 and the trench made by the anisotropic etching 15 for the later connection electrode. The distance between the trenches with the gate electrodes 21 and the ditch 15 for the connection electrode is essentially determined by the thickness of the oxide layer 24 ,

To make sure that one below the trench bottom 152 in the second semiconductor zone 12 produced highly doped first connection zone ( 16 in the 1 to 6 ) a sufficiently large distance in the lateral direction to the gate dielectric 22 so that this terminal zone does not affect the channel characteristics of the MOS transistor, it is desirable to keep the distance between the trench and the gate electrode 21 and the ditch 15 to make as large as possible for the connection electrode. In the previously by means of 7 explained method for producing this trench 15 However, this distance is limited by the thickness of the oxide layer 24 ' , which can not be realized arbitrarily thick to mechanical stress in the device structure, with increasing thickness of the oxide layer 24 ' increase, limit.

One possibility is the distance between the heavily doped connection zone in the second semiconductor layer 12 in the lateral direction to the gate dielectric 22 regardless of the distance between the trench 15 and the trench with the gate electrode 21 to adjust, consists in the preparation of the connection zone 16 using the basis of 3 explained method. In this method is on sidewalls of the trench 15 a protective layer 41 applied when carrying out the implantation process for the preparation of the connection zone 16 the implantation area at the bottom of the trench 152 bounded in the lateral direction.

Another method for producing a heavily doped junction region in the second semiconductor layer 12 which allows the distance of this connection zone to the trench with the gate electrode 21 regardless of the distance between the trench and the gate electrode 21 and the ditch 15 for the connection electrode is described below with reference to 8a to 8c explained.

Referring to 8a In this process, first a spacer layer 51 made, for example, the entire surface is deposited on the component array. This spacer layer 51 is, for example, a layer of a deposited oxide (TEOS) or a nitride layer. Furthermore, this spacer layer can 51 also several partial layers, for example a first deposited oxide layer 51A and a subsequently deposited nitride layer 51B show what is dashed in 8a is shown.

Referring to 8b Subsequently, an implantation method is performed, through which dopant atoms of the second conductivity type through the spacer layer 51 over the ditch floor 152 in the second semiconductor layer 12 be implanted. The insulation plugs 24 . 25 prevent in this case an implantation of dopant atoms in areas of the semiconductor body, which in the lateral direction adjacent to the trench 15 are arranged. On the side walls 151 of the trench 15 prevents the spacer layer 51 an implantation of dopant atoms of the second conductivity type in the first semiconductor layer 11 , While the dopant atoms in the region of the trench bottom 152 penetrate the spacer layer vertically, dopant atoms in the region of the side walls 151 of the trench at most at a very shallow angle on the spacer layer 51 under which they meet the spacer layer 51 but can not penetrate. The spacer layer 51 In this method, therefore, it acts as a protective layer, which dopes the measuring area in the region of the side walls 151 of the trench 15 prevented. The spacer layer also limits in the region of the trench bottom 152 the implantation region, ie the region in which dopant atoms are implanted, in the lateral direction. The thickness of the spacer layer 51 serves to adjust the distance between this implantation area, and thus the highly doped terminal zone produced by the implantation 16 , and the trench with the gate electrode 21 ,

It is for adjusting the distance of the heavily doped junction zone 16 to the gate electrode 21 sufficient, the spacer layer 51 on the side walls 151 of the trench 15 manufacture. Optionally, referring to 9 hence the possibility of the spacer layer prior to performing the implantation procedure 51 anisotropic re-etching, ie in particular from the trench bottom 152 to remove.

Referring to 8c showing the device structure after performing further process steps becomes the spacer layer 51 after making the heavily doped junction zone 16 removed and the ditch 15 is filled in an already explained manner with an electrode material for the preparation of the connection electrode, wherein this connection electrode in the manner already explained two partial layers, namely a barrier layer 33 and an electrode layer 34 can have. Optionally, there is the possibility of making the connection electrode 33 . 34 a heavily doped connection zone 17 in the first semiconductor layer 11 manufacture. Creating this highly doped junction zone 11 For example, by a by means of 6a explained implantation of dopant atoms of the first conductivity type at an angle to the vertical angle.

LIST OF REFERENCE NUMBERS

11

first semiconductor zone, source zone

12

second semiconductor zone, body zone

13

third semiconductor zone, drift zone

14

fourth semiconductor zone, drain zone

15

dig

15 '

first trench section

16, 17

highly doped connection zones

18

recess

21

Gate-electrode

22, 23

dielectric

24 '

oxide

25 '

filling layer

24, 25

insulation plugs

31 ', 31

protective layer

32

screen oxide

33

barrier layer

34

electrode layer

41

metallic protective layer

42

metallic protective layer

43, 44

Dotierstoffmaterialschicht

51

spacer layer

100

Semiconductor body

101

Front side of the semiconductor body

102

Rear side of the semiconductor body

151

Grave side wall

152

grave soil

Claims (18)

Method for producing a connection electrode for a first semiconductor zone ( 11 ) and a second semiconductor zone ( 12 ), which are arranged one above the other and are doped complementary to one another, comprising the method steps: - producing a trench ( 15 ) passing through the first semiconductor zone ( 11 ) to the second semiconductor zone ( 12 ) extends that the first semiconductor zone on sidewalls ( 151 ) of the trench and the second semiconductor zone ( 12 ) at least on one floor ( 152 ) of the trench is exposed, - application of a protective layer ( 31 ; 41 ) on the side walls ( 151 ) of the trench ( 15 ) such that the second semiconductor zone ( 12 ) on the ground ( 152 ) of the trench ( 15 ), - establishing a first connection zone ( 16 ) in the second semiconductor zone ( 12 ) by placing dopant atoms above the ground ( 152 ) of the trench ( 15 ) into the second semiconductor zone ( 12 ), the terminal zone ( 16 ) of the same conductivity type as the second semiconductor zone ( 12 ), but is doped higher, - depositing an electrode layer ( 34 ) at least on the side walls and the bottom of the trench for the preparation of the connection electrode. Method according to claim 1, in which - the protective layer ( 31 ) is a dopant-containing layer, and wherein - the first and second semiconductor regions ( 11 . 12 ) is heated to a predetermined temperature for a predetermined period of time, so that dopant atoms from the protective layer ( 31 ) into one of the two semiconductor zones ( 11 ; 12 ), resulting in a second junction zone of the same conductivity type as one of the two semiconductor zones (FIG. 11 ; 12 ), but is more highly doped. Method according to Claim 1 or 2, in which the first connection zone ( 16 ) is produced by implantation of dopant atoms and subsequent performance of a temperature step. Method according to Claim 3, in which, prior to the implantation, a litter layer ( 32 ) on the side walls ( 152 ) and the ground ( 151 ) of the trench ( 15 ) is applied. Method according to Claim 1 or 2, in which the first connection zone ( 16 ; 17 ) by diffusion of dopant atoms from a dopant material layer ( 43 ) with which the trench ( 15 ) is at least partially filled. Method according to one of the preceding claims, in which the protective layer ( 31 ) is a layer of dielectric material which is removed prior to making the terminal electrode. Method according to one of Claims 1 to 5, in which the protective layer ( 31 ) is an electrically conductive layer on one ( 11 ) of the two semiconductor zones remains and to which the electrode layer is applied. Method according to one of the preceding claims, in which the protective layer ( 31 ) is a dopant-containing layer and in which the first and second semiconductor layer ( 11 . 12 ) are heated for a predetermined period of time to a predetermined temperature, so that the dopant atoms from the protective layer ( 31 ) diffuse into the one (11) of the semiconductor zones and there form a second connection zone (FIG. 17 ) form. Method according to Claim 7, in which the protective layer ( 41 ; 42 ) consists of a metal and in which the first and second semiconductor zone ( 11 . 12 ) is heated to a predetermined temperature for a predetermined period of time, so that the protective layer ( 41 ; 42 ) with the semiconductor material of the one semiconductor zone ( 11 ; 12 ) enters a metal-semiconductor compound. Method according to one of the preceding claims, wherein prior to the production of the electrode layer ( 34 ) a barrier layer on the sidewalls ( 152 ) and the bottom of the trench is applied. Method according to Claim 1, in which the protective layer ( 51 ) is an oxide layer or a nitride layer. Method according to Claim 1, in which the protective layer ( 51 ) a first sub-layer ( 51A ) of an oxide and a second sublayer ( 51B ) of a nitride. Method for producing a connection electrode for a first semiconductor zone ( 11 ) and a second semiconductor zone ( 12 ), which are arranged one above the other and are doped complementary to one another, comprising the method steps: - producing a first trench section ( 15 ' ) extending at least into the first semiconductor zone ( 11 ) and the side walls ( 151 ' ), on which the first semiconductor zone ( 11 ), - establishing a first connection zone ( 17 ) in the first semiconductor zone ( 11 ) after making the first trench section ( 15 ' ) adjacent to the sidewalls of the first trench section ( 15 ' ) by introducing dopant atoms via these sidewalls into the first semiconductor zone (FIG. 11 ), - producing a further trench section that extends into the second semiconductor zone ( 12 ) extends from a floor ( 152 ' ) of the first trench section ( 15 ' ), - establishing a second connection zone ( 16 ) of the same conductivity type as the second semiconductor zone ( 12 ), but is doped higher, in the second semiconductor zone ( 12 ) below a bottom of the further trench section, - depositing an electrode layer ( 34 ) at least on the side walls and the bottom of the trench for the preparation of the connection electrode. Method according to Claim 13, in which the first and second connection zones ( 17 . 16 ) are each prepared by means of an implantation process. Method according to Claim 14, in which, before the implantation process is carried out, a litter layer ( 32 ) at least on the areas of the trench ( 15 ) is applied, adjacent to which the first and second terminal zone is made. Method according to one of claims 13 to 15, wherein prior to the production of the electrode layer ( 34 ) a barrier layer on the sidewalls ( 152 ) and the bottom of the trench ( 15 ) is applied. Method for producing a connection electrode for a first semiconductor zone ( 11 ) and a second semiconductor zone ( 12 ), which are arranged one above the other and are doped complementary to one another, comprising the method steps: - producing a trench ( 15 ) passing through the first semiconductor zone ( 11 ) to the second semiconductor zone ( 12 ) extends that the first semiconductor zone on sidewalls ( 151 ) of the trench and the second semiconductor zone ( 12 ) at least on one floor ( 152 ) of the trench is exposed, - establishing a first connection zone ( 17 ) in the first semiconductor zone ( 11 ) after making the trench ( 15 ) by implantation of dopant atoms at least at a first angle to the sidewalls (US Pat. 151 ) of the trench ( 15 ) in the side walls ( 151 ) of the trench ( 15 ), - establishing a second connection zone ( 16 ) in the second semiconductor zone ( 12 by implantation of dopant atoms at least at a second angle different from the first angle with respect to the sidewalls (US Pat. 151 ) - deposition of an electrode layer ( 34 ) at least on the side walls and the bottom of the trench for the preparation of the connection electrode. Method according to claim 17, wherein prior to the production of the electrode layer ( 34 ) a barrier layer on the sidewalls ( 152 ) and the bottom of the trench is applied.

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