JP2009016474A - Method of manufacturing semiconductor device and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a barrier film present between metal electrodes needs to be insulated since the barrier film is conductive, even though a thick metal electrode can be formed on the surface of a semiconductor element using a plating method by forming the barrier film when forming the metal electrode on the surface of the semiconductor element. <P>SOLUTION: A conductive barrier film 10 is formed on the surface of the semiconductor element 14 where an interlayer insulating film 12 is formed. After forming the metal electrode 5 on the surface of the barrier film 10, the semiconductor element 14 is thermally oxidized. The barrier film 10c in a region where the metal electrode 4 is not formed is oxidized and indicates insulation. Thus, the metal electrodes are insulated with each other. Also, for the barrier films 10a and 10b in a region where the metal electrode 5 is formed, the metal electrode 5 acts as a mask and they keep conductivity without being oxidized. Thus, the conduction of the metal electrode 5 and the semiconductor element 14 is secured. Thereafter, by removing an oxide film 22 on the surface of the metal electrode 5, the conduction of the metal electrode 5 is secured as well. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a technique for manufacturing a semiconductor device by forming a metal electrode on the surface of a semiconductor element covered with an interlayer insulating film having a contact hole. In particular, the present invention relates to a technology that can satisfy both of the following conditions.
(1) Between the surface of the semiconductor element constituting the bottom surface of the contact hole and the metal electrode, it is conductive and has the ability to suppress diffusion of the metal constituting the electrode into the material constituting the semiconductor element. Forming a barrier film.
(2) A plurality of contact holes are formed in the interlayer insulating film, and the barrier film existing between the adjacent metal electrodes corresponding to the adjacent contact holes does not conduct the adjacent metal electrodes.

When forming a metal electrode that is electrically conductive on the surface of a semiconductor element that forms the bottom surface of a contact hole formed in an interlayer insulating film, various conditions must be satisfied.
(1) When the metal constituting the electrode diffuses into the material constituting the semiconductor element, the characteristics of the semiconductor device change with time. In particular, when the semiconductor element is made of silicon and the metal electrode is formed by a plating method, the metal that can be formed by the plating method is likely to diffuse into the silicon, so this problem becomes important. In the prior art, when a semiconductor element is formed on a silicon substrate, a method of plating a metal on the surface of the silicon substrate to form a metal electrode is not employed.
(2) A plurality of metal electrodes may be formed on one semiconductor element. For example, if the semiconductor element is an IGBT, an emitter electrode, a gate electrode, and a collector electrode are required. The electrodes need to be insulated from each other.
(3) In order to cope with the problem of (1), the metal constituting the electrode constitutes the semiconductor element while being conductive between the surface of the semiconductor element constituting the bottom surface of the contact hole and the metal electrode. It is effective to form a barrier film having an ability to suppress diffusion into the material.
(4) When a conductive barrier film is formed between adjacent metal electrodes, conduction between adjacent metal electrodes is caused by the barrier film. It must be ensured that no conductive barrier film remains between adjacent metal electrodes.
(5) A material having an ability to suppress diffusion of the metal constituting the electrode into the material constituting the semiconductor element generally has high resistance to acid and alkali, and is difficult to remove by etching. That is, patterning is difficult. There is a barrier film in a range covering the bottom surface of the contact hole, and it is difficult to perform patterning so that no barrier film exists between adjacent metal electrodes. This also hinders the practical application of the method of plating a metal on the surface of a semiconductor element to form a metal electrode.
(6) The thickness of the metal electrode is also important. If it is too thin, a large thermal stress acts on the semiconductor element when wire bonding is performed on the electrode surface, and the semiconductor element is damaged, or heat generated in the semiconductor element is passed through the electrode. The ability to dissipate heat may be insufficient. A plating method is suitable for forming a thick metal film. However, at present, there is no suitable method for patterning the barrier film, and it is difficult to adopt a plating method that can manufacture a thick metal film at low cost.

At present, metal electrodes are often formed on the surface of a semiconductor element using aluminum. Aluminum is difficult to form by plating or CVD (chemical vapor deposition), and is usually formed by PVD (physical vapor deposition). However, if the thick film is formed by the PVD method, the manufacturing cost is greatly increased, so it is difficult to increase the thickness of the metal electrode.
In order to form a thick metal film at a low cost, a plating method is suitable. However, as described above, the metal that can be formed by the plating method easily diffuses into silicon or the like constituting the semiconductor element, and thus requires a barrier film, and it is difficult to etch and pattern the barrier film. There is a problem that it is difficult to insulate between adjacent metal electrodes.

There is no way to remove the barrier film. For example, the dual damascene method is known. In the dual damascene method, finally, a multilayer wiring having a cross-sectional structure shown in FIG. The multilayer wiring is realized by laminating an insulating lower layer 36 and an insulating upper layer 34. A wiring 38 is formed on the surface of the lower layer 36. A groove 41 is formed on the surface of the upper layer 34, and a through hole 40 is formed at the end of the groove 41. The through hole 40 is formed at a position corresponding to the wiring 38 of the lower layer 36. The surface of the lower layer 36 constituting the bottom surface of the through hole 40, the wall surface of the through hole 40, and the wall surface of the groove 41 are covered with the barrier film 32, and the inside is filled with metal.
The metal 31 filled in the groove 41 realizes a wiring formed on the surface of the upper layer 34. The metal 30 filled in the through hole 40 makes the wiring 38 in the lower layer 36 and the wiring 31 in the upper layer 34 conductive.
FIG. 11A shows the manufacturing stage. First, the upper layer 34 is formed of an insulating material on the surface of the lower layer 36 on which the wiring 38 is formed. Next, the groove 41 and the through hole 40 are provided in the upper layer 34. Since the through hole 40 is formed at the position of the wiring 38 in the lower layer 36, the surface of the wiring 38 is exposed on the bottom surface of the through hole 40. Next, the barrier film 32 is formed on the entire surface of the upper layer 34 in which the grooves 41 and the through holes 40 are formed. As a result, the barrier film 32 is formed on the entire surface of the upper layer 34, the side wall of the groove 41, the side wall of the through hole 40, and the surface of the lower layer 36 constituting the bottom surface of the through hole 40 (that is, the surface of the wiring 38). . Next, the metal film 30 is formed on the entire surface of the barrier film 32 by a plating method. Next, the surface is mechanically polished to remove the barrier film 32 formed near the upper surface of the metal film 30 and the upper surface of the upper layer 34. Thus, the cross-sectional structure shown in FIG.
The above-described method is to manufacture a multilayer wiring, and the metal filling the through hole 40 and the metal constituting the wiring 38 in contact with the metal are the same type, and it is not necessary to prevent the diffusion between them. The barrier film 32 prevents the metal from diffusing into the interlayer insulating film.

Assuming that the above technique is applied to the surface of a semiconductor device, the following becomes possible.
(1) A plurality of metal electrodes (corresponding to the metal film 30 filling the through holes 40) are formed on the surface of the semiconductor element (corresponding to the lower layer 36).
(2) The barrier film 32 is interposed between the surface of the semiconductor element constituting the bottom surface of the contact hole (corresponding to the through hole 40) formed in the interlayer insulating film (corresponding to the upper layer 34) and the metal electrode. Can do.
(3) By polishing beyond the bottom surface of the groove 41, the barrier film 32 positioned between adjacent metal electrodes can be removed. Insulation between adjacent metal electrodes can be ensured.
(4) The metal electrode can be formed by a plating method that can be carried out at low cost.

  However, even if the above technique is hypothesized, a metal electrode having a required thickness may not be formed. In the above method, a metal electrode thicker than the thickness of the upper layer 34 cannot be formed. In practice, however, there is a situation where it is difficult to increase the thickness of the upper layer 34. With a normal method, it is difficult to form the upper layer 34 having a thickness of 5 μm or more. Even if it is assumed that the dual damascene method is applied to the surface of a semiconductor element, if a metal electrode having a thickness of 5 μm or more is required, the necessity cannot be met.

Patent Document 1 describes a technique for removing a barrier film by plasma etching. If the plasma etching method disclosed in Patent Document 1 is adopted, the barrier film can be etched and removed at a portion where the barrier film is unnecessary. However, when the plasma etching method is employed, even the metal electrode is etched, which causes a problem that it is difficult to form a metal electrode having a desired thickness. In addition, the etched metal is scattered in the etching apparatus, which causes a problem that the etching apparatus must be frequently maintained. Furthermore, the etched metal is reattached to the surface of the interlayer insulating film, causing a problem that adjacent metal electrodes are short-circuited. Furthermore, there is a problem that the metal electrode is corroded. For example, when copper is used as the material of the metal electrode, when plasma etching is performed using halogen, the halogen reacts with copper and the metal electrode is corroded.
It is expected that the above problem can be solved by forming a mask on the surface of the metal electrode and performing plasma etching. However, if the metal electrode is thick, a mask that covers the step of the thick metal electrode is formed. Difficult to do.

JP 2006-245558 A

In view of the above circumstances, a technology capable of meeting the following requirements is desired.
(1) A plurality of metal electrodes are formed on the surface of the semiconductor element.
(2) A conductive barrier film is interposed between the surface of the semiconductor element forming the bottom surface of the contact hole formed in the interlayer insulating film (the surface of the semiconductor element exposed on the bottom surface of the contact hole) and the metal electrode. This prevents the metal constituting the metal electrode from diffusing into the material constituting the semiconductor element while ensuring the conductivity between the semiconductor element and the metal electrode.
(3) There is no conductive barrier film between adjacent metal electrodes, and adjacent metal electrodes do not short-circuit.
(4) The metal film can be formed by a plating method capable of forming a thick metal film at low cost.

  The present invention was created to meet the above requirements. In the present invention, a technique is adopted in which a barrier film existing between adjacent metal electrodes is oxidized to change the barrier film existing between adjacent metal electrodes into an insulator. In the present invention, since the barrier film is not etched, the above-mentioned many problems are solved at once.

The present invention can be embodied in a method for manufacturing a semiconductor device. In the method of the present invention, a semiconductor device having the following characteristics, that is, the surface of a semiconductor element is covered with an interlayer insulating film having a plurality of contact holes, and the surface of the semiconductor element constituting the bottom surface of the contact hole (contact hole) A semiconductor device in which a metal electrode that is electrically conductive through a barrier film is formed on the bottom surface of the semiconductor element exposed on the bottom surface of the semiconductor element and between adjacent metal electrodes is insulated is manufactured. To do. The manufacturing method of the present invention includes a step of covering the surface of a semiconductor element with an interlayer insulating film having a plurality of contact holes, and forming a barrier film on the surface of the semiconductor element constituting the surface of the interlayer insulating film and the bottom surface of the contact hole A step, a step of forming a metal electrode at a position corresponding to each contact hole, a step of thermally oxidizing the surface of the semiconductor element covered with the barrier film and the metal electrode group, and a surface of the thermally oxidized metal electrode group A step of removing the thermal oxide film from the substrate.
The barrier film is conductive and has a capability of suppressing diffusion of the metal constituting the metal electrode into the material constituting the semiconductor element, and is formed of a material that changes to an insulating property when oxidized. The metal electrode group is formed so that adjacent metal electrodes are separated from each other.

In the manufacturing method of the present invention, in order to prevent adjacent metal electrodes from being short-circuited, a method of removing the barrier film by etching is not used. Instead, a barrier film is formed of a material that changes to an insulating property when oxidized, and the surface of the semiconductor element covered with the barrier film and the metal electrode group is thermally oxidized.
In this case, since the barrier film is not oxidized in the range covered with the metal electrode group, conductivity is maintained. With the conductive barrier film, conduction between the surface of the semiconductor element and the metal electrode can be ensured. On the other hand, the barrier film positioned between the adjacent metal electrodes is oxidized to be insulative.
In the manufacturing method of the present invention, since a method for removing the barrier film by etching is not used, a material that is difficult to etch can be used. A material having a high ability to suppress diffusion of the metal constituting the metal electrode into the material constituting the semiconductor element has not been used so far because it is difficult to etch. The metal that can be formed by plating has the property of easily diffusing into the material constituting the semiconductor element. In the present invention, since the barrier film is not etched, a material having a higher diffusion suppressing ability is selected. Thus, a barrier film can be formed. According to the method of the present invention, it is possible to form a metal electrode by plating after forming a barrier film on the surface of a semiconductor element.
The present invention is that metal electrodes can be formed by a plating method, and is not limited to the plating method. For example, even when a metal electrode is formed by a CVD method or the like, it is possible to enjoy the advantage of not using a method of removing the barrier film by etching.
Since the barrier film is not removed by etching, even the metal electrode is etched, the metal is scattered and contaminated in the etching apparatus, or the etched metal is reattached to the surface of the interlayer insulating film and is adjacent. There is no short circuit between the metal electrodes, or the metal electrodes react with the plasma gas and are not corroded.

  The manufacturing method of the present invention is particularly effective when the semiconductor element is formed on a silicon substrate. In this case, in the step of forming the barrier film, a tantalum and / or tantalum nitride film is formed, and in the step of forming the metal electrode group, the metal electrode group is formed by plating copper and the thermal oxide film is removed. In this step, it is preferable to expose the surface of the thermally oxidized semiconductor element to an acid.

Tantalum and / or tantalum nitride films are difficult to etch, but effectively inhibit copper from diffusing into silicon. When the barrier film is formed of a tantalum and / or tantalum nitride film, a metal electrode can be formed of copper. In this method, since the tantalum and / or tantalum nitride film is not etched, it is possible to use a tantalum and / or tantalum nitride film that is difficult to etch, and effectively suppresses copper from diffusing into silicon. .
Copper has the following various characteristics. (1) A thick film can be formed by plating. (2) Even if it is formed as a thick film, a large stress does not develop between the silicon substrate and the silicon substrate is not damaged even if the silicon substrate is thinned. (3) It has a high thermal conductivity, and it is easy to obtain a thick film.
Tantalum and / or tantalum nitride oxides are insoluble in acid, whereas copper oxides are soluble in acid. By exposing the surface of the thermally oxidized semiconductor element to an acid, the oxide covering the surface of the copper electrode can be removed and the conductive copper can be exposed.
According to this method, a metal electrode that can satisfy various characteristics required for the metal electrode can be manufactured.

  When forming a copper electrode group, a step of forming a copper base film on the surface of the barrier film before forming the copper electrode group, and a plating range restriction on the surface of the base film before forming the copper electrode group A step of forming a layer, and a step of removing a base film exposed between a plating range regulating layer and adjacent electrodes before thermal oxidation after forming a copper electrode group preferable. A through hole is formed in the plating range regulating layer at a position corresponding to the contact hole.

  If a copper base film is formed on the surface of the barrier film, a thick copper film can be easily obtained by electrolytic plating. If the plating range regulating layer is formed of a photoresist or the like, there is no need to etch and pattern a thick copper film later. Since the base film and the plating range regulating layer can be formed of a material that can be easily etched, there is no problem in thermally oxidizing the barrier film thereafter.

After the surface of the semiconductor element is exposed to an acid, a step of coating the surface of the copper electrode group with a nickel film may be performed.
The nickel film becomes a film that prevents oxidation of the copper electrode, and improves the wettability with the solder when wire bonding is performed on the electrode. When a thick electrode is formed only with nickel, the metal electrode may exert a large stress on the semiconductor element and damage the semiconductor element. When the surface of the copper electrode is coated with a nickel film, a thin nickel film can be used, and no great stress is applied to the semiconductor element.

After the surface of the copper electrode group is coated with a nickel film, a step of removing an oxide film of tantalum and / or tantalum nitride exposed between adjacent electrodes may be performed.
As described above, the oxide film of tantalum and / or tantalum nitride can be removed by etching. At this time, since the copper surface is etched, various problems occur. On the other hand, nickel is highly resistant to etching for oxide films of tantalum and / or tantalum nitride, and functions as a mask for protecting copper. If it is necessary to remove the tantalum and / or tantalum nitride oxide film, it can also be removed.

  The present invention has realized a novel semiconductor device. A semiconductor device realized by the present invention includes a semiconductor element, an interlayer insulating film that covers the surface of the semiconductor element and has a plurality of contact holes, a surface of the interlayer insulating film, and a bottom surface of the contact hole A barrier film covering the surface of the semiconductor element and a metal electrode formed at a position corresponding to each contact hole are provided. The barrier film located between adjacent metal electrodes is oxidized. The barrier film is conductive, has a capability of suppressing diffusion of the metal constituting the metal electrode into the material constituting the semiconductor element, and is formed of a material that changes to insulation when oxidized. Each metal electrode is electrically connected to the surface of the semiconductor element constituting the bottom surface of each contact hole through a non-oxidized barrier film, and the adjacent metal electrodes are separated from each other. . The adjacent metal electrodes are separated from each other, and the barrier film positioned between the adjacent metal electrodes is oxidized and changed to insulating properties, so that the adjacent metal electrodes are not short-circuited. Since each metal electrode is in contact with the surface of the semiconductor element through the barrier film, the metal constituting the metal electrode does not diffuse into the material constituting the semiconductor element.

One of the semiconductor devices realized by the present invention includes a semiconductor element formed on a silicon substrate, an interlayer insulating film covering the surface of the semiconductor element and having a plurality of contact holes, and an interlayer insulating film And a tantalum and / or tantalum nitride film covering the surface of the semiconductor element constituting the surface of the contact hole and the bottom surface of the contact hole, and a copper electrode formed at a position corresponding to each contact hole. The tantalum and / or tantalum nitride film located between adjacent electrodes is oxidized. Each metal electrode is electrically connected to the surface of the semiconductor element constituting the bottom surface of each contact hole through a non-oxidized tantalum and / or tantalum nitride film, and between adjacent metal electrodes. There is a gap.
The adjacent metal electrodes are separated from each other, and the tantalum and / or tantalum nitride film located between the adjacent metal electrodes is oxidized to change to an insulating property, so that the adjacent metal electrodes are short-circuited. There is nothing. In addition, each metal electrode is in contact with the surface of the semiconductor element through a non-oxidized tantalum and / or tantalum nitride film, so that conduction is ensured and copper is contained in silicon constituting the semiconductor element. It does not spread.

  When the surface of the copper electrode group is covered with nickel, the tantalum and / or tantalum nitride film may be removed between adjacent electrodes. Since nickel functions as a protective mask when etching a tantalum and / or tantalum nitride film, the tantalum and / or tantalum nitride film existing between adjacent electrodes can be removed.

In the present invention, the barrier film existing between the metal electrodes is oxidized to change the barrier film to insulating. In order to prevent the metal electrodes from being short-circuited, it is not necessary to etch and remove the barrier film, and the selection range of materials used for the barrier film is expanded. Without considering the ease of etching, it is possible to select a material having a high ability to suppress diffusion of the metal constituting the metal electrode into the material constituting the semiconductor element. For this reason, a metal electrode can be formed by plating after forming a barrier film on the surface of the semiconductor element. Thick metal electrodes can be manufactured at low cost by plating. Further, since the barrier film is not etched, it is possible to avoid various problems that occur with the etching.
A metal electrode that is formed on a surface of a semiconductor element such as an IGBT and made of a material that does not apply a large stress to the semiconductor element, and that has a high heat dissipation and a thickness that does not apply a large stress to the semiconductor element during wire bonding, It can be manufactured at low cost by a plating method.

The main features of the embodiments described below are first organized.
(Feature 1) An emitter electrode and a gate electrode are formed on the surface of the IGBT, and both are insulated.
(Feature 2) A plurality of emitter electrodes are divided and formed on the surface of the IGBT, and the divided emitter electrodes are insulated from each other.
(Feature 3) An interlayer insulating film is formed on the surface of the semiconductor element. The interlayer insulating film cannot be formed to 5 μm or more. A metal electrode thicker than the film thickness of the interlayer insulating film is formed on the surface of the semiconductor element.
(Feature 4) A thin copper film is formed on the surface of the barrier film by the PVD method.
(Feature 5) A copper plating film is formed by electroplating on the surface of a copper seed film formed by PVD.

FIG. 1 schematically shows a cross-sectional view around a metal electrode 5 of a semiconductor device 20 according to an embodiment of the present invention. The semiconductor device 20 is configured around the semiconductor element 14. The semiconductor element 14 is an IGBT, and a region 16a in which both an emitter region containing a high concentration of n-type impurities and a body contact region containing a high concentration of p-type impurities are formed adjacent to each other in a range facing the surface; A region 16 b is formed in which the surface of the gate region where the conductive polysilicon is filled in the trench is exposed on the surface of the semiconductor element 14. When the electrically conductive metal electrode 5a is formed in the region 16a, the emitter region and the body region of the semiconductor element 14 are connected to a ground point prepared outside the semiconductor element 14 using the metal electrode 5a. be able to. When the electrically conductive metal electrode 5b is formed in the region 16b, the gate region of the semiconductor element 14 is connected to a gate potential switching device prepared outside the semiconductor element 14 using the metal electrode 5b. Can do. A collector region (not shown) is formed on the bottom surface of the semiconductor element 14. When a metal electrode (not shown) that is electrically conductive is formed in the collector region, the collector region of the semiconductor element 14 is used as a power source that provides a positive potential via a motor coil or the like using the metal electrode. Can be connected. When the voltage is switched by the gate potential switching device, the potential of the gate region formed in the semiconductor element 14 is switched, and conduction / non-conduction between the emitter region and the collector region formed in the semiconductor element 14 is switched. The conduction / non-conduction of the motor coil or the like is switched.
In order for the semiconductor element 14 to function, it is necessary to form at least two metal electrodes 5a and 5b, and the metal electrodes 5a and 5b must be insulated.

  The surface of the semiconductor element 14 is covered with an interlayer insulating film 12. A contact hole 13 a is formed at a position corresponding to the region 16 a of the interlayer insulating film 12. The surface of the semiconductor element 14 is exposed at the bottom surface of the contact hole 13a. In this case, the surface of the emitter region and the surface of the body contact region are exposed on the bottom surface of the contact hole 13a. That is, the bottom surface of the contact hole 13a is composed of the emitter region and the surface of the body contact region. A contact hole 13 b is formed at a position corresponding to the region 16 b of the interlayer insulating film 12. The surface of the semiconductor element 14 is exposed at the bottom surface of the contact hole 13b. In this case, the surface of the gate region is exposed on the bottom surface of the contact hole 13b. That is, the bottom surface of the contact hole 13b is constituted by the surface of the gate region.

A barrier film made of tantalum or tantalum nitride is used for the surface of the interlayer insulating film 12, the surface of the emitter region and the body contact region constituting the bottom surface of the contact hole 13a, and the surface of the gate region constituting the bottom surface of the contact hole 13b. 10 is covered. The barrier film 10a covering the bottom surface of the contact hole 13a is in contact with the surface of the emitter region and the body contact region. The barrier film 10a is in contact with the emitter region and the body contact region with a low contact resistance, and an ohmic characteristic is obtained. The barrier film 10b covering the bottom surface of the contact hole 13b is in contact with the surface of the gate region. The barrier film 10b is in contact with the gate region with a low contact resistance, and an ohmic characteristic is obtained.
Of the barrier film 10, a thin copper film 8a is formed on the surface of the barrier film 10a covering the bottom surface of the contact hole 13a. A thin copper film 8b is formed on the surface of the barrier film 10b covering the bottom surface of the contact hole 13b. The thin copper films 8a and 8b are formed by the PVD method. The PVD method requires a higher cost than the plating method, but if it is a thin film, the PVD method only needs to be performed for a short time, and the thin copper films 8a and 8b can be formed at a low cost. The thin copper films 8a and 8b are films serving as bases when a thick copper film is formed by a plating method to be performed later, and can be referred to as seed films.
A plating film 4a, which is a thick copper film formed by plating, is formed on the surface of the seed film 8a. The plating film 4a is electrically connected to the emitter region and the body contact region via the seed film 8a and the barrier film 10a. A plating film 4b, which is a thick copper film formed by plating, is formed on the surface of the seed film 8b. The plating film 4b is electrically connected to the body region via the seed film 8b and the barrier film 10b.

A metal electrode 5a is formed by the plating film 4a and the seed film 8a formed by plating. The metal electrode 5 a is thicker than the interlayer insulating film 12 and protrudes on the interlayer insulating film 12. A metal electrode 5b is formed by the plating film 4b and the seed film 4b formed by plating. The metal electrode 5 b is thicker than the interlayer insulating film 12 and protrudes on the interlayer insulating film 12.
The barrier film 10 existing between the metal electrode 5a and the metal electrode 5b is thermally oxidized in a portion 10c indicated by a thick hatch. Tantalum or tantalum nitride becomes insulating when thermally oxidized. The barrier film 10 existing between the metal electrode 5a and the metal electrode 5b has been changed into an insulating property in the range 10c not covered with the metal electrode 5a or the metal electrode 5b, and between the metal electrode 5a and the metal electrode 5b. Is insulated. The barrier films 10a and 10b in the range covered with the metal electrode 5a or the metal electrode 5b are not thermally oxidized and maintain insulating properties.

Next, a method for manufacturing the semiconductor device 20 will be described.
First, as shown in FIG. 2, the interlayer insulating film 12 is formed on the surface of the semiconductor element 14. In the interlayer insulating film 12, contact holes 13a and 13b are formed in a range corresponding to the regions 16a and 16b.
Next, as shown in FIG. 3, a barrier film 10 made of tantalum or tantalum nitride is formed on the entire surface of the interlayer insulating film 12 by the PVD method. At this time, the surface of the semiconductor element constituting the bottom surface of the contact hole 13a (the surface of the emitter region and the body contact region) and the surface of the semiconductor element constituting the bottom surface of the contact hole 13b (the surface of the gate region) are also formed by the barrier film 10. Covered.
Next, a seed film 8 made of copper is formed on the surface of the barrier film 10 by the PVD method.

Next, as shown in FIG. 4, a frame is formed with a photoresist 18 on the surface of the seed film 8. Specifically, a mask having an opening formed in a range corresponding to the contact holes 13a and 13b is formed on the surface of the unexposed photoresist 18, and the photoresist 18 is exposed through the opening of the mask. The photoresist 18 in the range is removed. The photoresist 18 is formed with a frame in which through holes 19a and 19b are formed in a range corresponding to the contact holes 13a and 13b. The frame regulates the range in which the copper film is formed in the subsequent electroplating step.
Next, as shown in FIG. 5, an electrode is brought into contact with the seed film 8, and a copper film is formed by electroplating. The copper film grows from the seed film 8 and becomes thicker in the through holes 19a and 19b. A plated film 4a that is a thick copper film grows in the through hole 19a, and a plated film 4b that is a thick copper film grows in the through hole 19b.
Next, as shown in FIG. 6, the photoresist 18 is removed.
Next, as shown in FIG. 7, the seed film 8 in the region not covered with the plating films 4a and 4b is removed using sulfuric acid or the like. Since the seed film 8 is sufficiently thinner than the plating films 4a and 4b, only the seed film 8 can be removed. Since the barrier film 10 is resistant to acid, the barrier film 10 is not removed when the seed film 8 is removed. As a result, the barrier film 10 is exposed in the region where the plating films 4a and 4b are not formed.

  Next, as shown in FIG. 8, the semiconductor device 20 is heat-treated in an oxygen atmosphere to completely oxidize the barrier film 10 in the region 10c not covered with the metal electrodes 5a and 5b. Thereby, the barrier film in the oxidized region 10c becomes an insulator and insulates between the metal electrodes 5a and 5b. The barrier film 10 existing immediately below the metal electrodes 5a and 5b is not oxidized. Therefore, the barrier films 10a and 10b existing immediately below the metal electrodes 5a and 5b are still conductive, and the regions 16a and 16b of the semiconductor element 14 and the metal electrodes 5a and 5b can be kept conductive.

  Next, the copper oxide films 22a and 22b formed on the surfaces and side surfaces of the metal electrodes 5a and 5b are removed by heat treatment. In this embodiment, tantalum or tantalum nitride is used for the barrier film 10, and tantalum oxide is generated in the barrier film in the oxidized region 10c. Tantalum oxide is highly resistant to acids and alkalis. By removing the copper oxide films 22a and 22b using sulfuric acid, formic acid or the like, the copper oxide films 22a and 22b can be removed without affecting the barrier film or the semiconductor element 14 in the oxidized region 10c. it can. Thereby, the semiconductor device 20 of FIG. 1 is manufactured.

  In the present embodiment, as shown in FIG. 9, a step of forming protective films 24a and 24b made of nickel on the surfaces of the metal electrodes 5a and 5b from which the copper oxide films 22a and 22b have been removed is further provided. Is preferred. When the nickel protective films 24a and 24b are formed, oxidation of the metal electrodes 5a and 5b can be prevented. In the present embodiment, the protective films 24a and 24b can be easily formed only on the surfaces of the metal electrodes 5a and 5b by using the barrier film in the oxidized region 10c. The conductive metal electrodes 5a and 5b and the insulating barrier film 10c are exposed on the surface of the semiconductor device 20 of the present invention. By utilizing this difference in characteristics, a nickel protective film can be formed only on the surfaces of the metal electrodes 5a and 5b by plating or the like. In particular, in the present embodiment in which the metal electrodes 5a and 5b are made of copper, the protective films 24a and 24b made of nickel having a smaller ionization tendency than copper can be easily formed.

  In this embodiment, as shown in FIG. 10, a step of removing the barrier film in the oxidized region 10c may be further provided. The barrier film in the oxidized region 10c is removed by dry etching using chlorine or fluorine. In this embodiment, protective films 24a and 24b made of nickel are formed, and nickel is resistant to dry etching using chlorine or fluorine. Utilizing this characteristic, the barrier film in the oxidized region 10c can be easily removed.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
For example, the method of forming the metal electrodes 5a and 5b is not limited to the electroplating method. If the electroplating method is used, there is an advantage that a relatively thick copper film can be formed. The thickness of the copper film to be formed is not particularly limited, and a relatively thin copper film may be formed. When the metal electrodes 5a and 5b are formed in regions having different functions of the semiconductor element 14 such as an emitter region and a gate region, they are naturally insulated. However, when the metal electrodes are formed insulated from each other, only Not exclusively. In some cases, metal electrodes formed in a region having the same function are also insulated from each other. For example, in a semiconductor element 14 such as an IGBT, there are cases where a plurality of semiconductor structures are formed in the semiconductor element 14 and a plurality of emitter regions and gate regions corresponding to the respective semiconductor structures are formed. In such a semiconductor device, each semiconductor structure can be operated individually by insulating and forming metal electrodes formed in regions having the same function in each semiconductor structure. The present invention is also effective when forming such a metal electrode. Further, the semiconductor element 14 is not limited to the IGBT. What is necessary is just the semiconductor element 14 in which the metal electrodes 5a and 5b are formed.
In addition, the technical elements described in the present specification or drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

A sectional view of semiconductor device 20 of an example of the present invention is shown. A process of manufacturing the semiconductor device 20 will be described. A process of manufacturing the semiconductor device 20 will be described. A process of manufacturing the semiconductor device 20 will be described. A process of manufacturing the semiconductor device 20 will be described. A process of manufacturing the semiconductor device 20 will be described. A process of manufacturing the semiconductor device 20 will be described. A process of manufacturing the semiconductor device 20 will be described. A process of manufacturing the semiconductor device 20 will be described. A process of manufacturing the semiconductor device 20 will be described. A state in which a multilayer wiring is formed by a dual damascene method is shown, (A) shows a manufacturing stage of the multilayer wiring, and (B) shows a completed multilayer wiring.

Explanation of symbols

4. Plated films 4a, 4b ... Plated film 5 ... Metal electrodes 5a, 5b ... Metal electrode 8 ... Seed films 8a, 8b ... Seed film 10 ... Barrier films 10a, 10b, 10c ... Barrier film 13 ... Contact holes 13a, 13b ... Contact hole 12 ... Interlayer insulating film 14 ... Semiconductor element 16 ... Area 16a, 16b ... Area 18 ... Photoresist 19 ... Through hole 19a, 19b ... Through hole 20 ... Semiconductor device 22 ... Oxide films 22a, 22b ... Oxide film 24... Protective film 24 a, 24 b... Protective film 30... Metal film 31... Wiring 32.・ ・ ・ ・ Wiring 40 ・ ・ ・ ・ Through hole 41 ・ ・ ・ ・ Groove

Claims (8)

The surface of the semiconductor element is covered with an interlayer insulating film having a plurality of contact holes, and a metal electrode that is electrically conductive through a barrier film is formed on the surface of the semiconductor element that constitutes the bottom surface of the contact hole. , A method of manufacturing a semiconductor device in which adjacent metal electrodes are insulated from each other,
Coating the surface of the semiconductor element with an interlayer insulating film having a plurality of contact holes;
The surface of the semiconductor element that forms the surface of the interlayer insulating film and the bottom surface of the contact hole is conductive and has the ability to suppress the diffusion of the metal that constitutes the metal electrode into the material that constitutes the semiconductor element. Then, a process of forming a barrier film with a material that changes to insulation,
Forming a metal electrode where adjacent metal electrodes are separated from each other at a position corresponding to each contact hole;
Thermally oxidizing the surface of the semiconductor element covered with the barrier film and the metal electrode group;
Removing the thermal oxide film from the surface of the thermally oxidized metal electrode group;
A method for manufacturing a semiconductor device comprising: The semiconductor element is formed on the silicon substrate,
In the step of forming the barrier film, a tantalum and / or tantalum nitride film is formed,
In the step of forming the metal electrode group, the metal electrode group is formed by plating copper,
2. The method of manufacturing a semiconductor device according to claim 1, wherein in the step of removing the thermal oxide film, the surface of the thermally oxidized semiconductor element is exposed to an acid. Before forming a copper electrode group, a step of forming a copper base film on the surface of the barrier film;
Before forming the copper electrode group, a step of forming a plating range regulating layer in which a through hole is formed at a position corresponding to the contact hole on the surface of the base film;
Before the thermal oxidation after forming the copper electrode group, the step of removing the plating range regulating layer and the base film exposed between the adjacent electrodes,
The method of manufacturing a semiconductor device according to claim 2, further comprising:   4. The method of manufacturing a semiconductor device according to claim 2, further comprising a step of coating the surface of the copper electrode group with a nickel film after exposing the surface of the semiconductor element to an acid.   5. The semiconductor according to claim 4, further comprising a step of removing the oxide film of tantalum and / or tantalum nitride exposed between adjacent electrodes after the surface of the copper electrode group is coated with a nickel film. Device manufacturing method. A semiconductor element;
An interlayer insulating film covering the surface of the semiconductor element and having a plurality of contact holes;
Covers the surface of the semiconductor element that constitutes the surface of the interlayer insulating film and the bottom surface of the contact hole, and is conductive and suppresses diffusion of the metal constituting the metal electrode into the material constituting the semiconductor element. A barrier film made of a material that has the ability to change to insulating properties when oxidized,
Formed at a position corresponding to each contact hole, electrically connected to the surface of the semiconductor element constituting the bottom surface of each contact hole through a non-oxidized barrier film, and adjacent metal electrodes It has metal electrodes that are separated from each other,
A semiconductor device, wherein a barrier film positioned between adjacent metal electrodes is oxidized. A semiconductor element formed on a silicon substrate;
An interlayer insulating film covering the surface of the semiconductor element and having a plurality of contact holes;
A film of tantalum and / or tantalum nitride covering the surface of the semiconductor element constituting the surface of the interlayer insulating film and the bottom surface of the contact hole;
It is formed at a position corresponding to each contact hole, and is electrically connected to the surface of the semiconductor element constituting the bottom surface of each contact hole via a non-oxidized tantalum and / or tantalum nitride film. In addition, it has a copper electrode separated between adjacent electrodes,
A tantalum and / or tantalum nitride film positioned between adjacent electrodes is oxidized. A semiconductor element formed on a silicon substrate;
An interlayer insulating film covering the surface of the semiconductor element and having a plurality of contact holes;
A film of tantalum and / or tantalum nitride covering the surface of the semiconductor element constituting the surface of the interlayer insulating film and the bottom surface of the contact hole;
It is formed at a position corresponding to each contact hole, and is electrically conductive through a non-oxidized tantalum and / or tantalum nitride film on the surface of the semiconductor element constituting the bottom surface of each contact hole. The adjacent electrodes are separated from each other, and the surface is provided with a copper electrode coated with nickel,
A tantalum and / or tantalum nitride film is removed between adjacent electrodes.

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