JPH05114600A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To realize a highly reliable metal wiring by a method wherein the crystal grain diameter in a metal wiring film is made large and at the same time, the crystal grain boundaries between the crystal grains are turned into bamboo grain boundaries. CONSTITUTION:A method for manufacturing a semiconductor device is characterized by that the method is provided with a process for forming a metal wiring film 4 on a semiconductor substrate 1 formed with an element, a process for laminating a transmitting film 7, which transmits a laser beam and at the same time, consists of a material to prevent the laser beam from the 4 from being reflected, on the film 4, a process for performing a patterning on the laminated films 4 and 7 and a process, wherein the laser beam 15 is emitted and a short- time and high-temperature annealing is performed on the film 4 performed a patterning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, which is particularly used for forming highly reliable metal wiring.

[0002]

2. Description of the Related Art In general, higher density and higher speed of semiconductor integrated circuits have been realized mainly by miniaturization of elements.
One of the major problems with the miniaturization of device dimensions is the reliability of metal wiring. The failure generation mode of the miniaturized metal wiring of the semiconductor device is roughly divided into two modes. One is electromigration,
The other is stress migration.

Electromigration is a defect caused by an increase in current density in metal wiring. In addition to the miniaturization of the wiring width, the current density in the wiring tends to become higher and higher due to the high speed operation of the device. Since the life of the wiring due to electromigration failure is inversely proportional to the square of the current density, for example, if the wiring width is halved without changing the film thickness, the current density doubles and the wiring life becomes 1
It will fall to / 4.

Stress migration is a creep failure mode that occurs when a tensile mechanical stress is applied to wiring. This stress is caused by the difference in thermal expansion coefficient between the insulating film for protecting the wiring and the wiring metal,
It tends to increase as the wiring width becomes finer. In the case of Al wiring, which is often used as wiring for semiconductor devices,
When the wiring width is halved, the stress applied is approximately doubled. Since the life of the wiring due to this stress migration is proportional to the nth power of the wiring width (n = 3 or 4), miniaturization of the wiring width causes a large reduction in the wiring life.

Conventionally, Al is used for metal wiring of semiconductor devices.
Many films are used because they have characteristics such as ease of film formation and processing, low resistance, and easy formation of contacts with substrate silicon. However, since the Al wiring has a low melting point, the activation energy for atom transfer is small, and the resistance to electromigration and stress migration is small. Several countermeasures have been proposed for such a decrease in reliability of Al fine wiring. A typical example thereof is an Al alloy wiring in which an additive such as Cu, Ti, Pd, Mg, Hf, B or Nb is mixed in Al. More recently, A
A laminated structure wiring is used in which a so-called barrier metal film such as TiN or TiW is provided under the 1 film. Other,
A laser annealing method, a rapid annealing method, a high temperature bias sputtering film forming method, etc. for increasing the grain size of the Al film have been proposed.

These measures for improving the reliability of Al wiring have some effects. However, with respect to the reliability of the wiring width of 0.5 μm or less, which is supposed to be performed in the future, considering that the current density is further increased, it cannot be said to be sufficient as a reliability measure. As an ultimate measure against the reliability of the Al wiring, single crystallization of the Al film has been proposed which can fundamentally solve the occurrence of defects. It has been confirmed that a single crystal film, which completely eliminates the grain boundary that causes the failure, can be extremely reliable when used as a wiring.

[0007]

However, at present, the single crystal Al film is grown only on the underlayer of the single crystal.
For example, the present inventors have found that a single crystal Al film having a (111) plane orientation grows on the (111) plane of single crystal Si by any of the film forming methods such as the ion cluster beam method, the CVD method and the sputtering method. I have confirmed. However, most of the semiconductor wiring is formed on an amorphous oxide film except for a small portion such as a contact portion. In the above-mentioned film forming method, at present, only a polycrystalline Al film is grown on the amorphous film. Therefore, the single crystal Al wiring cannot be realized by the current film forming technology.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method of manufacturing a semiconductor device capable of improving the reliability of metal wiring as much as possible.

[0009]

A method of manufacturing a semiconductor device according to the present invention comprises a step of forming a metal wiring film on a semiconductor substrate on which an element is formed, and a step of transmitting a laser beam onto the metal wiring film. A step of stacking a transparent film made of a material that prevents reflection of the laser light from the metal wiring film; a step of patterning the stacked metal wiring film and the transparent film; And a step of annealing the metal wiring film.

[0010]

According to the semiconductor device manufacturing method of the present invention having the above-described structure, after the metal wiring is formed, the metal wiring film is irradiated with the laser beam through the transmissive film to perform high-temperature annealing for a short time. As a result, it is possible to grow the crystal grain size in the metal wiring film to a large number to reduce the number of grain boundaries and to form a bamboo structure, which enables reliability of the metal wiring such as electromigration resistance and stress migration resistance. It can be improved as much as possible.

[0011]

FIG. 1 shows the manufacturing process of a first embodiment of the manufacturing method according to the present invention. In the manufacturing method of this embodiment, first, an insulating film 2 is formed on a semiconductor substrate 1 on which an element (not shown) is formed, a contact hole (not shown) is opened, and then the insulating film 2 is formed on the insulating film 2. Then, a metal wiring film 4 made of, for example, Al and having a thickness of 0.4 μm is formed, and a transmission film 7 made of, for example, TiN and having a thickness of 0.05 μm, which transmits laser light, is formed on the metal wiring film 4 ( See FIG. 1 (a).

Next, after forming the resist film 10, the resist film 10 is patterned (see FIG. 1B),
The permeable film 7 and the metal wiring film 4 are etched using the patterned resist film 10 as a mask (FIG. 1).
(See (c)). After that, laser light, for example, an excimer laser 15 is irradiated at a power density of 0.1 J / cm ² for 40 ns to anneal the metal wiring film 4 for a short time (see FIG. 1D). Then, the transparent film 7 is removed to complete the metal wiring 4 '(see FIG. 1E). The permeable film 7 may be left without being removed if the permeable film is made of a conductive material.

The transparent film 7 transmits the laser light, prevents the transmitted laser light from being reflected from the metal wiring film 4, and efficiently transmits the power energy of the laser light to the metal wiring film 4. Any material may be used, and it may be formed of a material such as amorphous Si, Mo, or W.

Next, the reason for annealing after patterning the metal wiring film will be described. The crystal grain size after forming the Al film is shown in FIG. The particle size at this time is usually 1 μm
It is a value of the degree. Further, as can be seen from FIG. 2A, the shape of the grain boundary 21 is indefinite. In this Al film,
When heat treatment is performed at a temperature of about 400 ° C. using an ordinary diffusion furnace or the like, as shown in FIG. 2B, the Al film undergoes crystal growth and the grain size increases to about several μm. However, the shape of the grain boundary 22 remains indefinite and does not change. When the Al film is subjected to wiring processing (patterning) here, a part of the wiring becomes a region ABCD surrounded by a broken line, and this wiring includes many grain boundary triple points that are the locations where voids are generated due to electromigration. Wiring life is short. On the other hand, when the Al film having the grain size shown in FIG. 2A is annealed at a high temperature for a short time using a laser or the like,
As shown in FIG. 2 (c), the grain size grows to be several times larger than that in the case of performing normal furnace annealing. When the wiring of the Al film that has been subjected to the high-temperature annealing for a short time is processed, a part of the wiring is partly surrounded by a broken line EF shown in FIG.
It becomes GH and the number of grain boundaries decreases. As a result, the electromigration resistance is improved. However, FIG.
As can be seen from (c), the triple boundaries are included in the wiring with a certain probability, and although the effect of improving the electromigration resistance is improved, it is not so large.

On the other hand, considering the case where a high-temperature annealing is performed for a short time by using a laser after patterning the wiring film as in the present embodiment, the triple points of the grain boundaries indicated by the broken line before the annealing are performed. Exists. However, during annealing, due to the effect of surface tension, the grain boundary triple point disappears as the grain size grows in the recrystallization process, and the bamboo grain boundary 24 is formed. The wiring having such a structure has the highest electromigration resistance due to the increase in grain size due to grain size growth and the bamboo grain boundaries. Then, when a reliability test of stress migration was performed on the wiring having this structure,
The occurrence of defects was significantly reduced compared to the normal annealed product. Conventionally, bamboo grain boundaries have been regarded as a location where stress migration defects occur, and are not desirable for high reliability. However, as in this embodiment,
Most of the wiring that has been subjected to high-temperature annealing for a short time after patterning has bamboo grain boundaries, but the stress migration resistance is improved. The reason for this is not clear, but one is that the crystal grain size becomes large and the number of crystal grain boundaries decreases, and the grain boundaries annealed for a short time at high temperature have a small defect density such as vacancies. It is thought that it is because of things.

The particle size of the metal wire 4'in this embodiment in the wire length direction was 30 to 40 .mu.m.

As described above, according to this embodiment, the electromigration resistance and the stress migration resistance can be improved, and the reliability of the metal wiring can be improved. Further, since the reliability of the metal wiring is improved, the reliability of the semiconductor device with high density and high integration is also significantly improved.

In this embodiment, the metal wiring film 4 is irradiated with laser through the transparent film 7. However, the same effect can be obtained by directly irradiating the metal wiring film with laser without forming the transparent film. You can However, in this case, the power density of the laser light needs to be 5 times or more as compared with the case of irradiating the laser light through the transmissive film 7, so that the element formed on the semiconductor substrate is likely to be adversely affected.

Therefore, according to the method of this embodiment, the power density of the laser light is about 1/5 or less as compared with the case where the metal wiring film is directly irradiated with the laser light without passing through the transparent film, and the method can be formed on the semiconductor substrate. It is possible to reduce the adverse effect that the device suffers from. In this embodiment, if a reflective film that reflects laser light is formed on the exposed portion of the insulating film 2 that covers the region where the device is formed before laser light irradiation, the device can be irradiated with laser light. The adverse effect of can be further reduced.

Further, according to the method of this embodiment, the power density can be reduced as compared with the case where the metal wiring film is directly irradiated with the laser beam without passing through the transparent film, so that the irradiation area per irradiation can be made large. It becomes possible, and this makes 1 chip 1
It is possible to do it only once.

Further, since the grain boundary triple point is likely to be generated in the portion where the laser light is overlapped, the method of this embodiment is compared with the case where the metal wiring film is directly irradiated with the laser light without passing through the transmission film. As a result, highly reliable metal wiring can be obtained.

Next, a modification of the first embodiment is shown in FIG.
In the manufacturing method of this modified example, after patterning the Al wiring film 4 having a film thickness of 0.4 μm (see FIG. 3A), TiN is used.
The entire surface is covered with a transmission film 7 having a film thickness of 0.05 μm (see FIG. 3B), and then the excimer laser 15 is adjusted to 0.
Irradiation is performed at a power density of 1 J / cm ² for 40 ns (see FIG. 3C), and the transmission film 7 is removed (see FIG. 3D). A manufactured by such a modified method
The grain boundary structure of the 1-wiring has a bamboo structure as in the first embodiment, and the grain size in the wiring length direction is slightly larger than that produced by the method of the first embodiment.
It grew to 50 μm. Therefore, the reliability can be improved also by the method of this modification.

Next, FIG. 4 shows a manufacturing process according to the method of the second embodiment of the present invention. The method of this embodiment is the same as that of the first embodiment up to the point of stacking and patterning the Al wiring film 4 and the TiN film 7 (see FIG. 4A). Thereafter, a passivation film 8 made of SiO ₂ and having a film thickness of 0.5 μm is formed on the entire surface of the substrate 1 (see FIG. 4).
(See (b)), the excimer laser 15 is irradiated with a power density of 0.1 J / cm ² for 40 ns to perform high-temperature annealing for a short time (see FIGS. 4C and 4D). By using the method of the second embodiment, the grain boundary structure in the Al wiring 4'becomes a bamboo structure as in the first embodiment, and the heat storage effect of the passivation film 8 causes the grain size in the wire length direction. Is slightly larger than that of the first embodiment, and grows to 40 to 50 μm. Therefore, the electromigration resistance and the stress migration resistance can be improved also by the method of the second embodiment,
The reliability of the metal wiring can be improved. Further, since the reliability of the metal wiring is improved, the reliability of the highly dense and highly integrated semiconductor device is also significantly improved.

Next, FIG. 5 shows a manufacturing process according to the method of the third embodiment of the present invention. The method of this embodiment is similar to the method of the first embodiment up to the point where the insulating film 2 is formed on the substrate 1 and a contact hole with an element (not shown) is opened in this insulating film 2. To do. After that, Al with a film thickness of 0.2 μm
A film 4a is formed, a 0.0023 μm-thick Cu and a 0.0005 μm-thick Cr laminated film 5 is formed thereon, and a 0.2 μm-thick Al film 4b is further formed thereon (FIG. 5A).
reference). Then, a TiN film 7 having a thickness of 0.05 μm is formed and patterned (see FIG. 5A). Then, the excimer laser 15 is irradiated with a power density of 0.1 Jcm ² for 40 ns to perform high-temperature annealing for a short time (FIG. 5).
(See (b) and (c)). The laminated film 5 of Cu and Cr is provided in the Al films 4a and 4b in order to accelerate the grain size growth of the Al film. By using the method of the third embodiment, the grain boundary structure in the Al wiring 4'becomes a bamboo structure as in the first embodiment, and the grain size of the Al wiring 4'is further increased by Cu and Cr. Grown and 100 to 20
It becomes 0 μm. This makes it possible to improve the electromigration resistance and the stress migration resistance and improve the reliability of the metal wiring. Further, since the reliability of the metal wiring is improved, the reliability of the semiconductor device with high density and high integration is also significantly improved.

In the above first to third embodiments, Al has been described as an example of the material of the metal wiring film, but in addition to pure Al, Al--Si, Al--Si--Cu, Al--Si.
Similar effects can be obtained by using an Al alloy in which another metal is added to Al such as -Pd. Furthermore, C instead of Al
Needless to say, the same effect can be obtained by using other metals such as u, Au, Ag, W, and Mo.

By the way, in order to make the crystal grain boundaries in the metal wiring into bamboo grain boundaries and to increase the grain size, it is possible to use the method shown in FIG. 6, for example. In the method shown in FIG. 6, for example, the Al wiring film 4 having a film thickness of 0.4 μm is used.
A TiN barrier metal 3 having a thickness of 0.1 μm is provided below (see FIG. 6A), and after patterning, an excimer laser 15 is irradiated with a power density of 0.5 J / cm ² for 40 ns to perform high-temperature annealing for a short time. You may give (FIG. 6 (a),
(See (c)). In this case, the grain size of the Al wiring 4 ′ in the wiring length direction was 20 to 30 μm. The advantage of this wiring structure is that since a TiN barrier metal is provided under the Al wiring 4, mutual diffusion between Al and the Si substrate does not occur at the contact portion in the high temperature state during annealing, so that a junction spike defect is generated. Can be prevented. In the method shown in FIG. 6, a transparent film (not shown) may be provided on the Al wiring film 4 as in the first embodiment, and after patterning, high temperature annealing may be performed using a laser for a short time. In this case, the power density of the laser can be reduced and the grain size in the annealed Al wiring can be increased.

[0027]

As described above, according to the present invention, A
It is possible to increase the crystal grain size in metal wiring such as l as compared with the conventional method, and to make the crystal grain boundaries into bamboo grain boundaries, thereby improving electromigration resistance and stress migration resistance. Therefore, highly reliable metal wiring can be realized.
Further, by this, the reliability of the semiconductor device with high density and high integration can be greatly improved.

[Brief description of drawings]

FIG. 1 is a process sectional view of a semiconductor device manufactured by a method according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating differences in crystal grain size and crystal grain boundaries due to differences in annealing methods.

FIG. 3 is a process cross-sectional view of a semiconductor device manufactured according to a modification of the first embodiment of the present invention.

FIG. 4 is a process sectional view of a semiconductor device manufactured by the method of the second embodiment of the present invention.

FIG. 5 is a process sectional view of a semiconductor device manufactured by a method of a third embodiment of the present invention.

FIG. 6 is a process cross-sectional view of a semiconductor device manufactured by another method for obtaining a highly reliable metal wiring.

[Explanation of symbols]

 1 substrate 2 insulating film 4 metal wiring film 7 transparent film 15 laser light

Claims (3)

[Claims] 1. A step of forming a metal wiring film on a semiconductor substrate having an element formed thereon, and transmitting laser light on the metal wiring film and preventing reflection of the laser light from the metal wiring film. A step of stacking a transparent film made of a material, a step of patterning the stacked metal wiring film and the transparent film, and a step of irradiating laser light to anneal the patterned metal wiring film A method of manufacturing a semiconductor device, comprising: 2. The method of manufacturing a semiconductor device according to claim 1, wherein an insulating film that covers the metal wiring film is formed before laser irradiation. 3. The metal wiring film is formed so as to be a layered structure film in which another metal film for accelerating an increase in grain size of the metal is provided in the metal wiring film. Item 1. A method of manufacturing a semiconductor device according to item 1.