JP2000216160A - Semiconductor manufacturing method and semiconductor manufacturing apparatus - Google Patents

Abstract

[PROBLEMS] To provide a semiconductor manufacturing method and a semiconductor manufacturing apparatus which realize formation of fine multilayer metal wiring. SOLUTION: A metal oxide of copper or aluminum, silver, gold, platinum, tungsten, tantalum, titanium, cobalt, nickel, iron or a metal oxide of an alloy molecule thereof is converted into atomic hydrogen or a reducing gas of a hydrogen ion beam. It is locally reduced using a beam to form microstructures of metals and metal oxides.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor manufacturing method,
More particularly, the present invention relates to a semiconductor manufacturing method and a semiconductor manufacturing apparatus adapted to metal wiring formation.

[0002]

2. Description of the Related Art In the prior art, aluminum is mainly used for wiring of a semiconductor element. However, in order to realize an ultra-high performance element, there is a need for a wiring having low resistance and resistance to electromigration or the like. , Is shifting from aluminum wiring to copper wiring. There are roughly two types of copper wiring forming methods. These methods include a method of forming wiring from a copper thin film by an etching technique, and a method of forming wiring grooves or holes in an insulator and embedding copper (damascene method). In the etching technique, copper wiring is formed mainly by etching using a chlorine-based reaction gas. However, the process temperature becomes high due to the low vapor pressure of copper chloride, resulting in poor fine workability. Further, from the viewpoint of environmental protection, there is a problem such as treatment of chlorides. In the damascene method, three methods of embedding copper, namely, sputter deposition, electrolytic plating, and chemical vapor deposition, are mainly studied.
Embedding by sputter deposition or electrolytic plating is simple, but there is a problem in forming fine wiring. Although fine wiring can be formed by chemical vapor deposition, the electrical characteristics of the wiring are poor and the manufacturing cost is high. Currently, commercialization is performed by sputter deposition or electrolytic plating.

[0003]

In the above prior art, the increase in wiring resistance, which becomes remarkable with miniaturization of a device in a multilayer wiring, causes a voltage drop of a power supply line and a signal delay, which is a problem. Therefore, a wiring material having low resistance and excellent electromigration resistance is required. Furthermore, when an organic interlayer insulating film having a low dielectric constant is used in the future, it is necessary to lower the temperature of the wiring and perform a short-time process. Semiconductor devices have been miniaturized year by year, and their wirings also need to be miniaturized. From the viewpoint of environmental protection, a clean process that does not use dangerous gas is required.

SUMMARY OF THE INVENTION An object of the present invention is to propose a completely new semiconductor manufacturing method for lowering the process temperature, increasing the area and increasing the productivity, and an apparatus therefor in a technique for forming metal wiring such as copper.

[0005]

According to the present invention, a metal oxide such as copper is locally reduced using a beam of a reducing gas such as an atomic hydrogen or a hydrogen ion beam. Thereby, a fine structure of a metal and a metal oxide is formed, and the metal wiring is formed without embedding the metal or directly etching the metal wiring. Also,
In the present invention, a metal thin film is locally oxidized using a beam of an oxidizing gas such as atomic oxygen, ozone or an oxygen ion beam to form a fine structure of a metal and a metal oxide. It is also characterized by making wiring.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments.

(Embodiment 1) A method for forming a fine metal wiring of this embodiment will be described with reference to FIG. 1A and 1B are process diagrams. All are perspective views.

In this embodiment, a technique for forming a fine structure of a metal and a metal oxide by locally reducing the metal oxide using a beam of a reducing gas will be specifically described. FIG. 1 shows the embodiment. As shown in FIG. 1A, a titanium nitride (TiN) film 3 for preventing internal diffusion of copper was formed on a silicon oxide substrate 2 in a vacuum, and a copper oxide 4 was further formed thereon. The copper oxide 4 was formed by a method of depositing copper and then oxidizing it with oxygen and a method of directly depositing copper oxide by sputtering. In addition to the TiN film, refractory metals such as tungsten (W), titanium (Ti), tantalum (Ta), molybdenum (Mo), tungsten nitride (TiW), and tantalum nitride (TaN), and silicon nitride (SiN, Si ₃ N
_Even the nitride film such as ₄ ) has a barrier property. A TiN mask 5 was formed on the copper oxide 4 using a lithography technique using light or an electron beam used in a semiconductor process or a lithography technique using a scanning atomic force microscope. This was irradiated with an atomic hydrogen beam 1 having good directivity from above. At this time, the substrate provided with the copper oxide 4 is placed on a heating device and is heated and maintained at about 300 ° C. The atomic hydrogen beam 1 does not react on the mask 5 and the mask 5
Reacts with copper oxide 4 having no copper to reduce copper oxide 4 to copper.

As a result, as shown in FIG. 1B, the copper wiring 6 was formed after the reduction. During the reduction, the volume of copper oxide is reduced to 60% when it is changed to copper. Therefore, as shown in FIG. 1 (b), the volume of copper 6 is smaller than that of copper oxide 4, and the surface has irregularities. In general, it can be determined whether or not the reduction has been performed by elemental analysis of the copper wiring 6. In the present invention, however, the degree of reduction can be known from the volume change caused by the reduction. Since the copper oxide 4 is a dielectric in the case of CuO, the barrier film 3 is made of silicon nitride (SiN, Si ₃
If the N ₄ ) film is used, the copper wiring 6 can be used as an insulated metal wiring in the state of FIG. FIG. 1 (b)
Now, all the unmasked copper oxide 4 has been reduced,
By reducing it halfway, the thickness of the copper wiring can be controlled. In the present invention, the example of the copper material is shown, but other aluminum,
Metal wires could also be formed using metal atoms such as silver, gold, platinum, tungsten, tantalum, titanium, cobalt, nickel, iron, or metal oxides of their alloy molecules.

(Embodiment 2) A method of forming a fine metal wiring of this embodiment will be described with reference to FIG. 2A and 2B are process diagrams. All are perspective views.

In the first embodiment, a method of forming a metal / metal oxide structure by reduction is shown. However, the same can be applied to an oxidation reaction which is a reaction opposite to reduction. This embodiment specifically describes a technique for forming a microstructure of metal and metal oxide by local oxidation using a beam of an oxidizing gas such as atomic oxygen, ozone, fluorine, or an oxygen ion beam. explain. FIG. 2 shows the embodiment. FIG.
As shown in (a), a titanium nitride (TiN) film 3 for preventing internal diffusion of copper is formed on a silicon oxide substrate 2 in a vacuum, and a copper thin film 7 is further formed thereon by sputter deposition in a vacuum. Was formed. In addition to TiN film, tungsten (W),
High barrier metal such as titanium (Ti), tantalum (Ta), molybdenum (Mo), tungsten nitride (WN), tantalum nitride (TaN) and nitride film such as silicon nitride (SiN, Si ₃ N ₄ ) there were. On the copper thin film 7, a lithography technique using light or an electron beam used in a semiconductor process or a lithography technique using a scanning atomic force microscope is used.
A TiN mask 5 was prepared. This was irradiated with an atomic oxygen beam 8 having good directivity from above. At this time, the substrate on which the copper thin film 7 is attached is placed on a heating device in a vacuum, and
Heated and maintained at 300 ° C. The atomic oxygen beam 8
Nothing reacted on the mask 5, reacted with the copper thin film 7 without the mask 5, and oxidized the copper thin film 7 to copper oxide 4.

As a result, as shown in FIG. 2B, the copper wiring 6 was formed after being oxidized. At the time of oxidation, the volume of copper becomes 1.7 times when it is changed to copper oxide,
As shown in FIG. 2B, the copper oxide 4 expands in volume as compared with the copper thin film 7, and has irregularities on the surface. The determination as to whether or not local oxidation has occurred may be made by elemental analysis of these copper wirings 6. In the present invention, the degree of reduction can be known from the volume change due to this reduction. Copper oxide 4 is CuO
In the case of (1), since it is a dielectric, if a silicon nitride (SiN, Si ₃ N) film is used for the barrier film 3, the copper wiring 6 can be used as an insulated metal wiring in the state of FIG. In the present invention, an example of a copper material has been described. However, even if other metal atoms such as aluminum, silver, gold, platinum, tungsten, tantalum, titanium, cobalt, nickel, and iron or a metal of an alloy molecule thereof are used, Wiring could be formed.

(Embodiment 3) A method of forming fine metal wirings of this embodiment will be described with reference to FIG. 3A to 3H are process diagrams. All are perspective views.

In the first embodiment, a method of forming a single-layer metal wiring using a metal oxide as an insulating layer has been described.
FIG. 3 shows an embodiment of a method for forming a multilayer metal wiring using a low dielectric constant interlayer insulator. As shown in FIG. 3A, a titanium nitride (TiN) film 3 for preventing internal diffusion of copper was formed on a silicon oxide substrate 2 in a vacuum, and a copper oxide 4 was further formed thereon. The copper oxide 4 was formed by a method of depositing copper and then oxidizing it with oxygen and a method of directly depositing copper oxide by sputtering. In addition to the TiN film, refractory metals such as tungsten (W), titanium (Ti), tantalum (Ta), molybdenum (Mo), tungsten nitride (WN), and tantalum nitride (TaN), and silicon nitride (SiN, Si ₃ N ₄₎
And the like also had a barrier property. As shown in FIG. 3B, a TiN mask is formed on the copper oxide 4 by using a lithography technique using light or an electron beam used in a semiconductor process or a lithography technique using a scanning atomic force microscope. 5 was created. While heating the substrate on which the copper oxide 4 was attached to about 300 ° C., an atomic hydrogen beam having good directivity was irradiated from the direction perpendicular to the surface.

As a result, as shown in FIG. 3C, the copper wiring 6 was formed after the reduction. The titanium nitride film 5 used as a mask is removed by reactive etching (RIE) using carbon fluoride (CF ₄ ) (FIG. 3D), and copper oxide is etched with an acidic liquid such as sulfuric acid. , Copper oxide 4 was removed. After removing the copper oxide, FIG.
The copper wiring 6 is formed as shown in FIG. 3, but the copper wiring is not insulated because of the underlying titanium nitride film 3. Therefore, only the portion without copper wiring is selectively etched by RIE, and the silicon nitride (Si) shown in FIG.
₃ N ₄ ) Deposit the film 9. The silicon nitride film 9 is an insulator and has a role of preventing copper from diffusing into the insulating layer.
Next, an insulator having a low dielectric constant is embedded between the wirings as shown in FIG. A next wiring layer is formed thereon, and a connection hole or a groove is formed in the silicon nitride film 9 shown in the upper part of FIG. Then, as shown in FIG. 3H, a titanium nitride film 3 for the next wiring layer is formed, and the process from FIG. 3A is repeated again to form a copper wiring. By repeating this process, a desired multilayer copper wiring can be formed. In the present invention, an example of a copper material has been described. However, even if other metal atoms such as aluminum, silver, gold, platinum, tungsten, tantalum, titanium, cobalt, nickel, and iron or a metal of an alloy molecule thereof are used, Wiring could be formed.

(Embodiment 4) A method for forming fine metal wirings of this embodiment will be described with reference to FIG. 4A to 4H are process diagrams. All are perspective views.

In the second embodiment, a method of forming a single-layer metal wiring using a metal oxide as an insulating layer has been described.
FIG. 4 shows an embodiment of a method for forming a multilayer metal wiring using a low dielectric constant interlayer insulator. As shown in FIG. 4 (a), a titanium nitride (TiN) film 3 for preventing internal diffusion of copper is formed on a silicon oxide substrate 2 in a vacuum, and copper is deposited thereon by sputtering vapor deposition in a vacuum. A thin film 7 was formed. In addition to TiN film, tungsten (W), titanium (Ti),
Refractory metals such as tantalum (Ta), molybdenum (Mo), tungsten nitride (WN), and tantalum nitride (TaN), and nitride films such as silicon nitride (SiN, Si ₃ N ₄ ) also had barrier properties. As shown in FIG. 4B, a TiN mask is formed on the copper thin film 7 by using a lithography technique using light or an electron beam used in a semiconductor process or a lithography technique using a scanning atomic force microscope. 5 was created. The substrate provided with the copper thin film 7 was irradiated with an atomic oxygen beam 8 having good directivity from a direction perpendicular to the surface while heating the substrate to about 300 ° C.

As a result, as shown in FIG. 4C, the copper wiring 6 was formed after being oxidized. FIG.
In (d), copper oxide 4 was removed by etching copper oxide with an acidic liquid such as sulfuric acid. After that, the titanium nitride film 5 used as the mask is RIE using carbon fluoride (CF ₄ ).
(FIG. 4 (e)). After the removal of the mask, a copper wiring 6 is formed as shown in FIG. 4E, and a silicon nitride (Si ₃ N ₄ ) film 9 shown in FIG.
The silicon nitride film 9 is an insulator and has a role of preventing copper from diffusing into the insulating layer. Next, as shown in FIG. 4G, an insulator 10 having a low dielectric constant is embedded between the wirings. To form the next wiring layer on this and connect with the lower wiring,
A connection hole or a groove is formed in the silicon nitride film 9 shown in the upper part of FIG. Then, as shown in FIG. 4H, a titanium nitride film 3 for the next wiring layer is formed, and the process from FIG. 4A is repeated again to form a copper wiring. By repeating this process, a desired multilayer copper wiring can be formed. In the present invention, an example of a copper material has been described. However, even if other metal atoms such as aluminum, silver, gold, platinum, tungsten, tantalum, titanium, cobalt, nickel, and iron or a metal of an alloy molecule thereof are used, Wiring could be formed.

(Embodiment 5) A method of forming fine metal wirings of this embodiment will be described with reference to FIG. 5A to 5D are process diagrams. All are perspective views.

In the fourth embodiment, both the low dielectric constant insulator 10 and the silicon nitride film 9 having a high dielectric constant for preventing copper diffusion are used for the interlayer insulating film. The rate will increase. In this embodiment, a method for forming a barrier film for copper wiring without using the silicon nitride film 9 is shown in FIG. After FIG. 4D of the fourth embodiment, FIG.
(A) A TiN film 11 is formed as shown in FIG. After that, RIE
Etches the TiN film from above. As shown in FIG. 5B, the side wall of the copper wiring 6 and the upper TiN film remain as a barrier film. This is because the sidewall is hardly etched and the TiN film 3 is thinner than the TiN film 5 used for the mask, so that a barrier film can be formed around the copper wiring. Next, as shown in FIG. 5C, a low dielectric constant insulator 10 is embedded between the wirings. A TiN film 3 is formed thereon as shown in FIG. 5D, and a copper wiring of the next layer is formed. Since the upper TiN film 3 is directly connected to the barrier film around the lower copper wiring, it is not necessary to form the connection hole or groove described in the fourth embodiment. By repeating the above process, a multilayer copper wiring that effectively utilizes the characteristics of the low dielectric constant insulator can be created.
In the present invention, the example of the copper material is shown, but other aluminum, silver,
Metal wires could also be formed using metal atoms such as gold, platinum, tungsten, tantalum, titanium, cobalt, nickel, iron and the like, and metals of their alloy molecules.

(Embodiment 6) Although Embodiments 1 to 5 have been described in principle, FIG. 6 shows an embodiment incorporated in a vacuum apparatus. The basic configuration of the apparatus is a single-wafer type in which the substrate 18 can be guided into and out of the vacuum apparatus 12 through the gate valve 26. In the vacuum device 12, a substrate stage 23 having a substrate rotation and cooling / heating mechanism is installed in a vacuum device moving mechanism 24. The substrate stage 23 and the moving mechanism 24 are controlled by a stage controller 25, and are connected to the central controller 25 to comprehensively control information such as oxidation and reduction. The highly directional atomic hydrogen and oxygen source 14 generates a beam by a thermal dissociation method on a high-temperature tungsten filament, adjusts the oxidation-reduction rate by a reactive beam controller 13, and is connected to a central controller 15. ing. The degree of vacuum is monitored by a vacuum controller 16 using a vacuum gauge 17, and is connected to a central controller 15 for control of a vacuum pump and the like. A collimator 27 having a small cylindrical hole was placed on the outlet side of the atomic hydrogen / oxygen source 14 in order to increase the directivity of the reactive beam, and was used to create a finer structure. In this embodiment, a thermal dissociation method on a tungsten filament was used to form a reactive beam, but the same effect was obtained by using another plasma method or an ion beam method. However, the plasma method and the ion beam method easily damage the sample because the beam energy of atomic hydrogen or the like is high. The redox amount was confirmed by irradiating a laser beam from a helium neon laser light source 19 to the substrate being redox through a viewing window 20 of the vacuum device 12 and measuring the reflected laser light through a viewing window 21 with a laser intensity detector 22. . As described in the first and second embodiments, the surface is made uneven by oxidation and reduction. Therefore, the amount of oxidation and reduction is determined without damage and in real time from the difference in reflectance, and the information is sent to the central controller 15. The yield was improved by comprehensively judging the amount of oxidation / reduction, the rotational speed of the substrate, and the substrate temperature. In this embodiment, a single-wafer-type substrate transfer system is used, but the same effect can be obtained by a batch-type system.

[0022]

According to the invention, since local oxidation-reduction is in principle at the atomic level, it is also effective for fine structures, and the characteristics of the thin film are changed by oxidizing and used. The metal wiring can be formed by reducing the process steps of forming and filling the holes and grooves.

Further, by applying the present invention, the development of other semiconductor process technologies can be advanced, and the application to material elements having a metal / metal oxide structure such as a magnetic memory material can be developed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a metal wiring by reduction of a metal oxide of the present invention.

FIG. 2 is a schematic diagram showing a metal wiring formed by oxidation of a metal according to the present invention.

FIG. 3 is a process chart of Example 3 of forming a multilayer metal wiring by reduction of a metal oxide according to the present invention.

FIG. 4 is a process chart of Example 4 of forming a multilayer metal wiring by oxidizing a metal according to the present invention.

FIG. 5 is a process chart of Example 5 of forming a multilayer metal wiring by oxidizing a metal according to the present invention.

FIG. 6 is a schematic configuration diagram showing an apparatus for manufacturing a metal wiring by redox.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Atomic hydrogen beam, 2 ... Silicon oxide substrate, 3 ... Titanium nitride, 4 ... Copper oxide, 5 ... Titanium nitride mask, 6 ... Copper wiring, 7 ... Copper thin film, 8 ... Atomic oxygen beam, 9 ... Silicon nitride Film, 10 ... insulator, 11 ... titanium nitride film, 12 ...
Vacuum device, 13 reactive beam control device, 14 atomic hydrogen and oxygen source, 15 central control device, 16 vacuum degree control device, 17 vacuum gauge, 18 substrate, 19 laser light source, 20 peep Window, 21: viewing window, 22: laser intensity detection device, 23: substrate stage, 24: moving mechanism, 25
... Stage controller, 26 ... Gate valve, 27 ... Collimator.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Petek Harvoe 2520 Akanuma, Hatoyama-cho, Hiki-gun, Saitama Prefecture Inside of Hitachi, Ltd. (72) Inventor Kenichi Takeda 1-280, Higashi-Koikekubo, Kokubunji, Tokyo Inside the Central Research Laboratory (72) Inventor Kenji Hino 1-280 Higashi-Koigakubo, Kokubunji-shi, Tokyo F-term in the Central Research Laboratory, Hitachi, Ltd. DD88 FF16 FF18 5F033 HH07 HH08 HH11 HH13 HH14 HH15 HH16 HH18 HH19 HH20 HH21 HH23 HH32 HH33 KK07 KK08 KK11 KK13 KK14 KK15 KK16 KK18 KK19 KK20 KK21 KK23 KK32 KK33 MM05 MM11 PP15 QQ08 QQ09 QQ13 QQ19 QQ27 QQ53 QQ54 QQ59 QQ60 QQ61 QQ63 QQ68 RR06 XX03 XX24

Claims (11)

[Claims] 1. A reducing gas such as copper or aluminum, silver, gold, platinum, tungsten, tantalum, titanium, cobalt, nickel, or iron metal atoms or metal oxides of their alloy molecules in the form of atomic hydrogen or hydrogen ion beam. A method for manufacturing a semiconductor, comprising reducing locally using a beam to form a fine structure of metal and metal oxide. 2. An oxidizing gas of atomic oxygen, ozone, fluorine or an oxygen ion beam, wherein metal atoms of copper or aluminum, silver, gold, platinum, tungsten, tantalum, titanium, cobalt, nickel and iron and alloy molecules thereof are converted to atomic oxygen, ozone, fluorine and oxygen ion beams. A method for manufacturing a semiconductor, comprising: locally oxidizing the substrate using a beam to form a fine structure of a metal and a metal oxide. 3. A metal oxide is removed by etching to form a high melting point metal such as tungsten, titanium, tantalum, molybdenum, tungsten nitride, tantalum nitride, titanium nitride, a nitride or alloy thereof, and an insulating film of silicon nitride. 2. The semiconductor manufacturing method according to claim 1, wherein a multi-layered metal wiring is formed by forming a barrier film for preventing metal diffusion around the metal, inserting an interlayer insulating film between the wirings. 4. An etching method for removing metal oxides by etching, high-melting metals such as tungsten, titanium, tantalum, molybdenum, tungsten nitride, tantalum nitride, titanium nitride, nitrides and alloys thereof, and insulating films such as silicon nitride. 3. A method of manufacturing a semiconductor device according to claim 2, wherein a metal film is formed around the metal as a barrier film for preventing metal diffusion, and an interlayer insulating film is inserted between the wirings to form a multilayer metal wiring. 5. A barrier film is formed only around a metal wiring,
5. The method according to claim 4, wherein the capacitance between the wirings is reduced. 6. A reducing gas such as copper or aluminum, silver, gold, platinum, tungsten, tantalum, titanium, cobalt, nickel or iron metal atoms or metal oxides of their alloy molecules in atomic hydrogen or hydrogen ion beam. A semiconductor manufacturing apparatus comprising: means for reducing locally using a beam; and forming a fine structure of a metal and a metal oxide. 7. An oxidizing gas of atomic oxygen, ozone, fluorine or an oxygen ion beam, wherein a metal atom of copper or aluminum, silver, gold, platinum, tungsten, tantalum, titanium, cobalt, nickel or iron or an alloy molecule thereof is converted to atomic oxygen, ozone, fluorine or oxygen ion beam. A semiconductor manufacturing apparatus, comprising: means for locally oxidizing by using a beam; and forming a fine structure of a metal and a metal oxide. 8. The apparatus according to claim 1, further comprising: a device for measuring a reflection intensity of a laser for observing a redox process of a metal or a metal oxide and controlling an embedding amount; and a means for automatically controlling formation of a metal wiring. 7. The semiconductor manufacturing apparatus according to claim 6, wherein: 9. A multi-nozzle beam source and a collimator having a large number of holes for improving beam directivity, for redoxing a large-diameter wafer, and for oxidation-reduction in a wafer surface 9. The semiconductor manufacturing apparatus according to claim 8, wherein the amount is uniformly controlled to increase the area of the formation of complicated and fine metal wiring. 10. An apparatus for measuring a reflection intensity of a laser for observing a redox process of a metal or a metal oxide and controlling an embedding amount, and a means for automatically controlling formation of a metal wiring. The semiconductor manufacturing apparatus according to claim 7, wherein: 11. A multi-nozzle beam source, a multi-hole collimator for improving beam directivity,
11. The method according to claim 10, further comprising the step of redoxing a large-diameter wafer, uniformly controlling the amount of redox in the wafer surface, and increasing the area of the formation of complicated and fine metal wiring.
The semiconductor manufacturing apparatus according to the above.