JP3488586B2 - Method for manufacturing semiconductor device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of semiconductor devices.
Relates to a method, in particular, it is used in a multilayer wiring process, to a method of filling a conductive film in the connection hole and wiring trench or the like.

[0002]

2. Description of the Related Art With the recent trend toward higher integration and higher speed of semiconductor devices, miniaturization of electric circuits is progressing.
Miniaturization of the diameter of the connection hole that connects between wirings and between wirings,
Higher aspect ratios are becoming more and more advanced. Reflow film formation and plug formation by CVD film formation are being considered as a method of forming plug wirings for filling the next-generation high aspect ratio holes. In reflow molding, Al and Cu are used as C
For VD film formation, materials such as W, Al and Cu have been studied and put to practical use.

On the other hand, there is a dual damascene structure as a multilayer wiring structure. This structure is a wiring structure that is formed by filling the recesses formed in the wiring portion and the connection hole portion with a conductive film. In these structures, however, the aspect ratio of the recessed portion to be filled becomes high, so that the plug formation is further improved. In the wiring formation, there are severe conditions.

FIG. 24 shows a structure having a dual damascene structure element, which is formed in the multilayer wiring portion by the reflow film forming method. Further, W formed by the CVD method is used for forming the connection hole on the diffusion layer. In the reflow film formation, Ti is used as the reflow base, and TiAl ₃ is formed during the film formation by heating during filling, and a very high resistance layer is produced. In addition, when the connection hole having an aspect ratio of 3 or more is embedded, a void is generated, and there is a problem that the connection hole cannot be embedded.

On the other hand, in terms of the filling characteristics, CVD is used.
Excellent film formation.

Although there are blanket CVD film formation and selective CVD in CVD film formation, a wiring structure having a W contact plug formed by blanket CVD film formation and a manufacturing method thereof will be described below with reference to FIG. To do.

First, a field oxide film 142, a gate oxide film 143a, and a gate electrode 14 are formed on a Si semiconductor substrate 141.
3b and a SiN film 143c having a thickness of 150 nm formed on the side wall thereof and having a silicon surface exposed by being surrounded by these, a p ⁺ impurity diffusion layer is formed by using a well-known ion implantation method. 144 are formed. Then CVD
The SiO ₂ film 145 and the BPCG film 146 to 1.2
deposited to a thickness of μm, and p ⁺ impurity diffusion layer 144
Open a contact hole reaching up to (Fig. 25
(A)).

Next, on this structure, Ti (thickness 20 n
m) / TiN (thickness 70 nm) laminated film 147, 148
Was deposited by long-throw sputtering with a long distance between the target and the substrate, and 600 ° C. 3 in a nitrogen atmosphere.
Heat treatment for 0 minutes is performed, and the TiSi ₂ film 14 is formed on the contact bottom.
9 and the Ti / TiN laminated film 147, 1 is formed on the oxide film.
It is left at 48 (FIG. 25 (b)). Ti / at this time
The film thickness of the TiN laminated films 147 and 148 in the contact holes was about 10 nm / about 30 nm.

This underlayer is adhered to a glue-layer.
r) and a seed layer for CVD film formation, and on this structure, a mixed gas of a tungsten halide such as tungsten hexafluoride (WF ₆ ) and hydrogen (H ₂ ) is used as a reaction gas. A film is formed (FIG. 25C). After that, the W film on the entire surface is etched until four oxide films 146 are exposed to form a W plug 160 in the contact hole (FIG. 25D).

In blanket CVD film formation, W, Al,
Regardless of the material such as Cu, it is indispensable to form the blue-layer as the underlayer. However, when the contact holes are further miniaturized, firstly, the blue-layer is formed.
It is necessary to uniformly embed er in the contact hole. To this end, for example, CVD of Ti and TiN
Film formation is being studied. Specifically, TiN film formation by plasma CVD of TiCl ₄ and T film formation by MOCVD
Although the iN film is formed, at present, the specific resistance of TiN formed by sputtering film formation is 100 μΩ · cm, and the specific resistance of TiN formed by plasma CVD is 140 μm.
μΩ · cm, the specific resistance of TiN formed by MOCVD is as high as 400 μΩ · cm, and it is an object to suppress the resistance increase due to impurities mixed in the TiN film of the CVD film and the corrosion due to Cl. Become.

Further, in the selective film forming method in which the W plug is formed directly on the lower layer wiring, when the lower layer wiring is a wiring containing Al and Cu as the main components, a dissimilar metal interface is formed between W and the lower layer wiring. become. It is known that the dissimilar metal interface is weak in electromigration resistance and stress migration resistance, and is one of the factors that lower the reliability of the device.

Further, since the process is very sensitive to the surface condition of the substrate, it is well known that the process margin is very narrow and it is very difficult to prevent the loss of selectivity in the mass production line. is there. Further, in the miniaturization and high aspect ratio of the contact hole, pretreatment for obtaining a clean surface of the underlying layer becomes difficult, which causes nonuniform plug formation. Further Next Generation LS
In order to apply these processes to I, research and development of pretreatment technology are required.

[0013]

Therefore, the next-generation LSI
In order to form such a fine contact hole plug having a high aspect ratio, there are problems with the current plug forming technology, and it is not possible to follow the LSI design guidelines. In order to solve these problems, any technique requires further brush-up or new technique, and taking measures against these techniques is a means for extending the life of these techniques. At the same time, there is an urgent need to establish a new process for filling fine contact holes.

The present invention has been made under the above circumstances, and is a method of manufacturing a semiconductor device having a highly reliable conductive film filled in a fine connection hole or a wiring groove having a high aspect ratio.
The purpose is to provide the law .

[0015]

In order to solve the above problems, the present invention (Claim 1) forms an insulating film on a semiconductor substrate.
And a step of forming a recess in the insulating film,
A conductive element and a melting point lower than this element should be provided in the recess.
Forming a liquid phase containing a substance having, and
From the equilibrium composition to the composition in which the conductive element is excessive.
Moving to crystallize the conductive element, at least before
The step of forming a conductive film in the concave portion, and the step of forming the conductive film outside the concave portion.
And a step of removing a substance existing on the insulating film.
A method for manufacturing a semiconductor device is provided. .

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

According to the present invention ( claim 2 ), in the method for manufacturing a semiconductor device ( claim 1 ) described above, a liquid phase containing a conductive element and a substance having a melting point lower than that of the element in the concave portion. The step of forming is at least in the recess,
It is characterized by forming a solid phase alloy layer containing a conductive element and a substance having a melting point lower than that of the element, and then heating and melting the solid phase alloy layer.

According to the present invention ( claim 3 ), in the method for manufacturing a semiconductor device ( claim 1 ), a liquid phase containing a conductive element and a substance having a melting point lower than that of the element in the recess is provided. The step of forming is at least in the recess,
A material layer having a melting point lower than that of the conductive element is formed, the conductive element layer is formed, and the material layer having a melting point lower than that of the conductive element is heated and melted. It is characterized by comprising diffusing a conductive element.

According to the present invention ( claim 4 ), in the method for manufacturing a semiconductor device described above ( claim 1 ), a liquid phase containing a conductive element and a substance having a melting point lower than that of the element is present in the recess. The step of forming is at least in the recess,
Forming a material layer having a melting point lower than that of the conductive element, heating the material layer having a melting point lower than that of the conductive element to obtain a liquid phase, and supplying the conductive element to the melt. It is characterized by consisting of.

According to the present invention ( claim 5 ), in the method for manufacturing a semiconductor device described above ( claim 1 ), a liquid phase containing a conductive element and a substance having a melting point lower than that of the element in the concave portion. In the step of forming, a melt of a substance having a melting point lower than that of the conductive element, or a melt containing the conductive element and a substance having a melting point lower than this element is added to the recess. It is characterized by comprising filling while pressing.

According to the present invention ( claim 6 ), in the method for manufacturing a semiconductor device ( claim 1 ), the composition of the liquid phase is moved from an equilibrium composition to a composition in which the conductive element is excessive. The step of crystallizing the conductive element is characterized by lowering the temperature of the liquid phase or lowering and holding the temperature in a solid-liquid two-phase temperature region.

According to the present invention ( claim 7 ), in the method for manufacturing a semiconductor device ( claim 1 ), the composition of the liquid phase is moved from an equilibrium composition to a composition in which the conductive element is excessive. In the step of crystallizing the conductive element, the temperature of the liquid phase is lowered and maintained in a solid-liquid two-phase temperature region, the temperature of the liquid phase is raised, and the conductive element is supplied to the liquid phase. It is characterized in that it consists of cooling the phase.

According to the present invention ( claim 8 ), in the method for manufacturing a semiconductor device ( claim 1 ), the composition of the liquid phase is moved from an equilibrium composition to a composition in which the conductive element is excessive, In the step of crystallizing the conductive element, N, O,
And heat treatment in an atmosphere containing at least one selected from the group consisting of H and H.

According to the present invention ( claim 9 ), in the method for manufacturing a semiconductor device ( claim 1 ), the composition of the liquid phase is moved from an equilibrium composition to a composition in which the conductive element is excessive. The step of crystallizing the conductive element includes performing heat treatment in an atmosphere that forms a vapor phase compound with the substance having a low melting point, and removing the vapor phase compound.

According to the present invention ( Claim 10 ), in the method for manufacturing a semiconductor device ( Claim 1 ), the step of removing a substance existing on the insulating film outside the recess includes a gas containing halogen. Introducing to form a halide and removing the halide.

According to the present invention ( claim 11 ), in the method for manufacturing a semiconductor device ( claim 1 ), the halogen is at least one selected from the group consisting of chlorine, fluorine, iodine and bromine. It is characterized by

According to the present invention ( claim 12 ), a step of forming an insulating film on a semiconductor substrate, a step of forming a recess in the insulating film, and a barrier metal or the insulating film on at least a part of the inner surface of the recess. A step of forming a thin film made of a substance having a surface energy higher than that, a step of forming a liquid phase containing a conductive element and a substance having a melting point lower than this element in the recess; Moving the composition from an equilibrium composition to a composition in which the conductive element is in excess, crystallizing the conductive element to form a conductive film in the recess, and on the insulating film outside the recess. And a step of removing a substance existing in the semiconductor device.

According to the present invention ( claim 13 ), a step of forming an insulating film on a semiconductor substrate, a step of forming a concave portion in the insulating film, a conductive element in the concave portion, and a conductive element lower than this element A step of forming a liquid phase containing a substance having a melting point, and moving the composition of the liquid phase from an equilibrium composition to a composition in which the conductive element is in excess to crystallize the conductive element, A step of forming a conductive film therein, and a step of removing a substance existing on the insulating film outside the recess, and adding an additional element during or after crystallization of the conductive element It is characterized by

The present invention ( Claim 14 ) is characterized in that, in the method for manufacturing a semiconductor device ( Claim 13 ), the conductive element is a single element.

According to the present invention ( claim 15 ), in the method for manufacturing a semiconductor device ( claim 13 ), the additive element is an element for improving electromigration or stress migration resistance of the conductive film after crystallization. It is characterized by being.

According to the present invention ( claim 16 ), in the method for manufacturing a semiconductor device ( claim 13 ), the additive element is an element that lowers the solid solubility limit of the low melting point material after crystallization. Characterize.

The principle of the present invention resides in a technique of filling a high-aspect connection hole, which comprises forming a crystallized seed layer using a solid-liquid reaction and growing a conductive material.

That is, according to the present invention, the wiring / electrode material of a semiconductor element such as an FET is used for a substrate surface, a connection hole, a groove wiring portion,
When it is desired to form in a recess or the like near the element portion, an alloy containing a wiring / electrode material and a material having a lower melting point than that of the material and forming a simple eutectic system on the entire surface including the recess, or those Single layer film or multiple films composed of the above elements are deposited, or low melting point metal is formed on the substrate prior to the supply of wiring / electrode material, the temperature of the substrate is raised, and the liquid phase is formed near the desired process temperature. After that, by lowering the temperature or selectively removing the substance with a low melting point, the deviation from the equilibrium composition in the initial liquid phase is crystallized in the recesses, and the crystallization nuclei are used as seed phases. It is characterized in that a wiring / electrode material is formed or embedded on the substrate and in the recess.

In this case, the composition of the molten alloy before crystallizing the wiring / electrode material may be any composition that can obtain a liquid phase at a temperature below the upper limit of the desired process temperature, and the temperature for obtaining the liquid phase is It is only necessary that the temperature is equal to or higher than the melting point temperature of the low melting point material constituting the liquid phase and higher than the eutectic line temperature of the low melting point material and the wiring / electrode material forming the liquid phase.

Further, at the interface formed by the wiring material and the insulating film, which has a high density of non-uniform nucleation, that is, on the surface of the connection hole and the wiring groove, the bottom of the wiring groove, the edge of the connection hole bottom and the lower wiring surface By preferentially generating nuclei,
It is characterized in that wirings / electrodes are deposited or embedded in desired surfaces and recesses.

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to Examples of the present invention.

Example 1 FIG. 1 is a sectional view showing an Al plug forming method according to a first example of the present invention in the order of steps.

First, a substrate on which elements are formed (not shown)
A first wiring layer 2 is formed on top, and then an interlayer insulating film 3 is formed thereon as an interlayer insulating film. After that, the interlayer insulating film 3 is selectively etched to form the connection hole 4 and the wiring groove 5 (FIG. 1A).

After that, a eutectic alloy of Al and Sn Al--Sn
The alloy film 6 having a composition of x, for example, x = about 86 at% is formed by the sputtering method. Here, the sputtering is Al-S composed of a composition capable of forming a desired eutectic alloy film.
The eutectic alloy target of n or the mosaic target of Al and Sn was used. At this time, an Al—Sn alloy is previously prepared by using a sputtering method having a strong straightness in a direction perpendicular to the substrate surface, for example, a long throw sputtering method in which the distance between the substrate and the sputtering target (distance between TSs) is large. Formed in the connection hole and the wiring groove recess.

At this time, the substrate is heated until the Al—Sn film is in the liquid phase, and Al is filled in the connection hole and the wiring groove recess.
The -Sn film may be filled more uniformly. Also, Al-S
The deposited film thickness of the n film is set to a film thickness such that the amount of Al in the Al—Sn film can supply a sufficient amount to fill the connection holes and the wiring groove recesses (FIG. 1B).

Next, in the case of the alloy composition of this embodiment, the substrate is heated so as to be not lower than 420 ° C. and not higher than the desired process temperature to obtain the liquid phase of the Al—Sn alloy previously formed. . The desired process temperature is, for example, A
In addition to the sinter temperature of the 1-wiring, it refers to a temperature not higher than the highest temperature during the other multi-layer wiring forming process.

The previously deposited Al--Sn film is sufficiently in the liquid phase 6a.
, And the Sn composition 86 after holding for a time to reach an equilibrium state.
In the case of at%, the liquid phase is obtained from the equilibrium diagram 420
The temperature is lowered to a temperature sufficiently lower than the vicinity of ℃, for example, 350 ℃. As a result, Al-Snx (approximately x = 86 at
%) From the liquid phase of the alloy to the equilibrium composition Al-Sn at 350 ° C.
By reaching x (approximately x = 92.3 at%),
About 8 at% of Al having a surplus composition is crystallized on the insulating film including the connection hole and the wiring groove concave portion (FIG. 1C).

The Al crystallized film 6b filled the contact holes and the wiring groove recesses (FIG. 2A). Here, the Al crystallized film has a maximum concentration of Sn equal to or less than the maximum concentration at which the Al crystallized and the liquid phase Sn are in equilibrium when the liquid phase of the Al-Sn film is formed in the connection hole or the wiring groove. It is a film containing Al in the crystallized film as a main component. Further, the temperature of the crystallization step of Al is a temperature range where a two-phase coexisting region of a solid phase and a liquid phase is formed in the equilibrium state, and in the case of the above composition of Al-Sn alloy, the temperature is on the equilibrium diagram. Above 228 ° C, which is the eutectic line, and below 420 ° C, which passes through the liquidus line.

The Al crystallization step can be realized not only by moving the equilibrium concentration by lowering the temperature but also by selectively reducing the Sn concentration. The point in the crystallization process of Al that is the conductive film is to crystallize the conductive film by moving the equilibrium concentration. Also, Al and Sn
Is a combination of metals that form a eutectic, and the two metals do not form a compound at equilibrium and separate into two phases. Al
Eutectic alloying with Sn, which is a metal that has a very low melting point relative to the melting point of, and does not form a compound, lowers the melting point below the temperature of the process normally used in the LSI process. The liquid phase can be easily obtained.

By obtaining a liquid phase having a high fluidity, not only is it easy to fill a fine pattern or a connection hole having a high aspect ratio, but also Al, which is a relatively high melting point metal, is crystallized from the liquid phase alloy. By doing so, it is possible to lower the process temperature for filling the connection hole and the wiring groove. In the present embodiment, Al-S is directly introduced into the connection hole and the groove wiring.
Although the n film is formed, the barrier film may be formed before the Al—Sn film is formed. As a result, the wettability of the Al—Sn film with the underlying layer is improved, and the Al—Sn film is more likely to be formed during the initial film formation. Can be filled with good coverage.

Subsequently, the Sn layer segregated on the surface of the substrate and the Al—Sn layer and the Al layer outside the connection hole and the wiring groove are removed. In this removing step, a gas containing chlorine (Cl ₂ ) is introduced into the chamber, the gas is caused to flow on the substrate surface, and Sn is added.
The layer and excess Al-Sn layer were removed as chloride. S
Since n has a high chloride vapor pressure and is higher than the chloride vapor pressure of Al, Sn can be removed with a certain selection ratio with respect to Al by selecting the conditions.

At this time, if the substrate is heated, the chloride removal efficiency is higher. The flow of the gas containing Cl ₂ is
Higher effects were obtained by RIE using a gas containing chlorine and etchback using CDE. Also, at this time, by adding a trace amount of a gas having oxidizing power, RIE and C
During the etch back process by DE, the selection ratio of Al and Sn can be more effectively taken, and the plug or wiring 7 made of an Al crystallized film can be formed in the connection hole or the wiring groove. Further, as a method of processing the plug and the wiring, the gas containing chlorine has been described as an example, but the same effect can be obtained with the gas containing Br, F, and I. Furthermore, the Sn layer, the Al—Sn layer, and the Al layer outside the connection hole and the wiring groove may be removed by chemical mechanical polishing (hereinafter, CMP) (FIG. 2B).

Now, the above-mentioned embodiment is shown by a rough process flow. (1) Al-Sn to the pattern recess (connection hole or wiring groove)
Film formation (2) Liquid phase acquisition of Al-Sn alloy by temperature rise, or filling of connection hole by liquid phase (3) Al crystallization at interface and connection hole bottom by moving equilibrium concentration (both Al-Sn (Al crystallization from mixed phase of liquid phase and solid phase of eutectic alloy) (4) Al nucleus growth using Al crystallization nuclei of (3) as seed layer, and plug mainly composed of Al by layer growth Forming (5) is composed of a plug containing Al as a main component and a wiring / plug processing step of leaving only in the groove wiring portion. One of the points is that in the step (1) or (2), the Al-Sn alloy in the embodiment is formed in the connection hole and is held in the connection hole and the wiring groove in the liquid phase. .

In the above embodiments, Al--Sn was previously prepared.
As a means for forming the alloy film inside the connection hole or the wiring groove, the long throw sputtering method which is a PVD film forming method in which the sputtered particles have a high rectilinearity is used. An anisotropic sputtering method such as a collimation sputtering method in which a collimator for depositing sputtered particles other than the components is inserted, or a bias sputtering method in which a DC voltage or a high frequency voltage is applied to the semiconductor substrate may be used.

Further, if the Al--Sn alloy film can be formed in the connection hole and the wiring groove, the usual sputtering method is also possible.
The ICB (Ion Clus
terBeam) Film formation and other applications are also possible. In addition, when the Al—Sn alloy film is deposited at this time, the substrate may be heated in advance to a temperature near the liquidus temperature of the alloy composition, or the film formed in the connection hole or the wiring groove may be formed of Al—Sn alloy or Sn. Even a single substance can be used regardless of the film type. Further, in order to hold the liquid phase alloy at least in the connection hole or the wiring groove, the liquid phase may be obtained by heating it under a pressure stress.

Example 2 Similar to Example 1, first, a first wiring layer 2 was formed on a substrate (not shown) on which elements were formed, and then,
An interlayer insulating film 3 is formed on it. After that, the connection hole 4 and the wiring groove 5 which are connected to the first wiring layer 2 are formed in the interlayer insulating film 3 by using the photolithography and the RIE process (FIG. 1A). At this time, the opening diameter of the connection hole 4 is 0.1 μm and the aspect ratio is 10. Then Al
And Sn eutectic alloy Al-Snx, for example x = about 88 at
%, The alloy film 6 having a composition of 9% is formed by a sputtering method, and the Al—Sn eutectic alloy is filled in the connection hole 4 and the wiring groove 5 in advance. At this time, the thickness of the Al—Sn eutectic alloy film is 2 μm.
Met.

Next, the substrate is heated to 450 ° C. to obtain the liquid phase of the previously deposited Al—Sn eutectic alloy. Then Al-
While maintaining the liquid phase of the Sn eutectic alloy in the connection hole 4 and the wiring groove 5, the temperature is lowered to 350 ° C. As a result, 4.4 at% Al in the initial Al-Sn alloy was formed on the surface of the insulating film.
Is crystallized to form Al in the connection hole and the wiring groove. After that, the conductive film other than the connection holes and the wiring groove recesses and the segregated Sn
, Etch back by RIE or CDE, or CMP
Then, a conductive film is formed in the connection hole and the wiring groove.

Select Overfilling Probability of Connection Hole C
As a result of comparison with VD-W film formation, 0.1 μm diameter, A / R to
In the 10 connection holes, 10% of the W film formed by selective CVD was overfilled with respect to the intended film thickness of 2 μm, and the film thickness in the plug was greatly varied. On the other hand, in the plug formed in this example,
It was possible to achieve a film thickness within the hole with almost the same level of variation, and sufficient overfilling was possible.

Example 3 As shown in FIG. 3A, first, a first wiring layer 12 was formed on a substrate (not shown) on which elements were formed, and then an interlayer insulating film was formed thereon. 13 is formed. After that, the interlayer insulating film SiO ₂ film 13 is selectively etched to form a connection hole 14 and a wiring groove 15 having a diameter of 0.1 μm and an aspect ratio of 10 (FIG. 3A).

Then, a tin film is formed by the sputtering method. At this time, a connection hole or a wiring groove is previously formed by using a sputtering method having a strong straightness in a direction perpendicular to the substrate surface, for example, a long throw sputtering method in which the distance between the substrate and the sputtering target (distance between TSs) is large. The Sn film 16 was formed in the recess. At this time, the substrate may be heated to around 232 ° C. to more uniformly fill Sn into the connection hole and the wiring groove. An Al film 17 was formed on the entire surface of this substrate by sputtering, and a laminated film of Sn and Al was formed while maintaining a vacuum (FIG. 3B).

This substrate is held at 420 ° C. or higher and at a desired process temperature or lower. Here, the desired process temperature refers to, for example, the sinter temperature of the Al wiring, or a temperature equal to or lower than the highest temperature during other multilayer wiring forming steps. The liquid phase 16a of Sn previously deposited by this heat treatment and the liquid phase 17a of the Al film near the Sn / Al interface
While diffusing Al into the Sn film liquid phase,
A liquid phase alloy of -Sn is obtained (Fig. 3 (c)).

By lowering the temperature of the substrate and keeping it at a constant temperature of, for example, about 300 ° C., excess Al with respect to the equilibrium concentration at the constant temperature is crystallized on the insulating film.
6b was used as a seed layer for Al liquid phase growth to crystallize Al, thereby filling the contact hole and the wiring groove (FIG. 4).
(A)). Here, the crystallization process temperature of Al is a temperature region in which a two-phase coexisting region of a solid phase and a liquid phase is formed in an equilibrium state, and the temperature exceeds 228 ° C. which is the eutectic line.

Subsequently, the segregated Sn layer, Al—Sn layer 17b and Al layer 16b outside the connection hole and the wiring groove are removed. In this removing step, a gas containing Cl ₂ gas is caused to flow, or the substrate is simultaneously heated during the gas flow to remove it as a chloride. The flow of the gas containing Cl ₂ gas can be efficiently performed also by RIE using a gas containing chlorine and Etchivac by CDE.

At this time, it is also possible to remove Sn more efficiently by adding a trace amount of oxidizing gas, and to leave and form the connection plug and the groove wiring made of the Al crystallized film. . Further, the Sn layer, the Al layer, and the Al—Sn layer outside the connection hole and the wiring groove can be removed by CMP. Thus, the plug and groove wiring 16b made of an Al crystallized film were formed in the connection hole and the wiring groove (FIG. 4B).

In the formation of the connection plug and the wiring of this embodiment, at the Sn / Al interface, Al is around 420 ° C.
And the amount of Al that can be present in the eutectic region where solid-liquid two-phase coexist with is diffused into the liquid-phase Sn film. By keeping the temperature of the Al-Sn liquid phase alloy formed by this diffusion constant and keeping it at a constant temperature, it is possible to crystallize Al of a composition deviated from the equilibrium composition into the liquid phase alloy. This Al crystallization is
A plug is formed by being generated from the surface of the insulating film pattern and the connection hole.

When the Sn film or Al film is formed and the melting heating step is performed, it is possible to carry out heating in a vacuum or in the same chamber as the Sn or Al film forming chamber.

Further, instead of the Sn film formed initially,
It is also possible to form a Sn-Al film having a large Sn composition, and a film having a composition that allows the temperature at which the liquid phase is obtained in consideration of other steps may be used.

Embodiment 4 First, a first wiring layer 22 is formed on a substrate (not shown) on which elements are formed, and then an interlayer insulating film 23 is formed thereon.
To form. After that, the interlayer insulating film 23 is selectively etched to form a connection hole 24 and a wiring groove 25 having a diameter of 0.1 μm and an aspect ratio of 10 (FIG. 5A).

After that, a tin film is formed on the entire surface of the substrate by the sputtering method. At this time, the connection hole 24 and the wiring groove are formed by using a sputtering method having a strong straightness in the direction perpendicular to the substrate surface, for example, a long throw sputtering method in which the distance between the substrate and the sputtering target (TS distance) is large. The Sn film 26 is formed in 25 (FIG. 5).
(B)). At this time, the substrate may be heated to more uniformly fill the connection hole 24 and the wiring groove 25 with Sn.

Subsequently, the substrate was transferred to another chamber capable of heating and sputtering film formation while maintaining the vacuum. The film formation is not particularly limited to sputtering.
Here, by keeping the substrate at a constant temperature of, for example, about 300 ° C., the liquid phase state of the Sn film previously deposited is obtained by this heat treatment. While maintaining this state, Al is supplied by sputtering (FIG. 5 (c)). As a result, Al-
At 300 ° C. in the solid-liquid two-phase coexisting region of Sn, an amount of Al exceeding the equilibrium composition diffuses into Sn, and an excessive amount of Al relative to the equilibrium concentration at the constant temperature holding temperature is deposited on the SiO ₂ insulating film. And the Al crystallization nuclei 27 are used as a seed layer for the liquid phase growth of Al to form the Al crystallization film 28 in the connection hole 54.
And it was embedded in the wiring groove 55 (FIG. 6A).

Here, the crystallization process temperature of Al is a temperature region where a two-phase coexisting region of a solid phase and a liquid phase is formed in the equilibrium state, and the temperature exceeds 228 ° C. which is the eutectic line. Then, the Sn layer segregated outside the concave portion of the connection hole and the wiring groove, Al
-The Sn layer and the Al layer are removed, and a plug or wiring 28 containing aluminum as a main component is formed only in the connection hole and the wiring groove.
Was formed (FIG. 6B).

Further, instead of the Sn film formed at the beginning,
It is also possible to form a Sn-Al film having a large Sn composition, and a film having a composition that allows the temperature at which the liquid layer is obtained in consideration of other steps may be used.

During the step of crystallizing Al from the liquid phase Sn film or the liquid phase Al—Sn film while supplying Al, or after the step of crystallizing Al of Al, the temperature is lowered to crystallize Al. You can go. Further, in the Al crystallization process by the temperature decrease, the temperature may be decreased several times during the Al supply process.

Embodiment 5 With reference to FIGS. 7 and 8, a connection plug and groove wiring forming process according to this embodiment will be described.

First, a substrate on which elements are formed (not shown)
A first wiring layer 32 is formed on top of it, and then an interlayer insulating film 33 is formed on it. After that, a connection hole 34 and a wiring groove 35 for connecting to the first wiring layer are formed in the interlayer insulating film 33 by using a photolithography process and an RIE process (FIG. 7A).

The natural oxide film on the first wiring layer 32 exposed at the bottom of the connection hole 34 is removed by surface treatment such as reverse sputtering. Next, the connection hole 34 and the wiring groove 3
5 is filled with the Sn film 36 (FIG. 7B).

After that, Sn outside the connection hole 34 and the wiring groove 35 is removed by RIE, CDE, or CMP (FIG. 7C).

Next, after removing the natural oxide film on the surface of Sn36, an Al film 37 is formed by sputtering while maintaining a vacuum. The native oxide film on the surface of Sn36 may be removed by reverse sputtering or H ₂ or SiH ₄
The substrate may be heated while flowing a reducing gas such as.

The presence of a natural oxide film at the Sn / Al interface prevents Al from diffusing into the Sn liquid phase.
If a natural oxide film is present at the Sn / Al interface, Sn
Due to the change in volume that occurs when the film becomes a liquid phase, voids may occur at the interface with the Al film that is a solid phase. In order to prevent this, when depositing an Al film on the Sn film,
A step of removing the natural oxide film is performed.

By subjecting this substrate to heat treatment at a temperature at which the Sn film becomes a liquid phase, for example, 450 ° C., S in the liquid phase is obtained.
After the n film is obtained, Al is diffused into the Sn film which is a liquid phase, and Sn is diffused into the upper Al film, so that the liquid phase of Al—Sn is formed in the connection hole 34 and the wiring groove 35. Are formed (FIG. 8A).

After that, the Sn film, the Al film and the Al—Sn film outside the connection hole 34 and the wiring groove 35 are removed by etching back by RIE, CMP or the like to form a connection plug and a groove wiring 38 (FIG. 8). (B)).

As shown in FIGS. 9 and 10, after the connection holes and the wiring groove recesses are filled with Sn, the substrate is heated, and Al is supplied by sputtering or the like while holding the Sn liquid phase 39. Good.

Further, thereafter, the temperature may be lowered in the chamber to carry out the step of crystallizing Al in the connection hole and the wiring groove. Liquid phase Sn performed while supplying Al
During the step of crystallizing Al from the film or the liquid Al—Sn film, or after the step of crystallizing Al of Al, the temperature may be lowered to crystallize Al. Further, in the Al crystallization process by the temperature decrease, the temperature may be decreased several times during the Al supply process.

Furthermore, in this embodiment, the Sn film is filled in the connection hole and the wiring groove, but it may be filled with the Sn-Al film.

Sixth Embodiment A connection plug and groove wiring forming process according to the present embodiment will be described with reference to FIGS. 11 and 12.

First, a first wiring layer 42 is formed on a silicon substrate (not shown) on which elements are formed, and then an interlayer insulating film 43 is formed thereon. After that, a connection hole and a wiring groove connected to the first wiring layer 42 are formed in the interlayer insulating film 43 by using a photolithography process and an RIE process.

The natural oxide film on the first wiring layer 42 exposed at the bottom of the connection hole is removed by surface treatment such as reverse sputtering. Next, in the connection hole and the wiring groove, Al-
The alloy film 44 of Snx (for example, x = 81.6 at%) is filled (FIG. 11A). Then, Sn outside the connection hole and the wiring groove is removed by RIE, CDE, or CMP (FIG. 11B).

Next, after removing the natural oxide film on the surface of the Al—Sn eutectic alloy film, the temperature is raised to a temperature (for example, 450 ° C.) at which the Al—Sn eutectic alloy film having the above composition becomes a liquid phase, and then 400 Cool down to ℃ and put A inside the connection hole and wiring groove.
The l-layer 45 is crystallized. Next, the Al film 46 is formed by a method such as sputtering (FIG. 11C).

The temperature of this laminated film is lower than the temperature at which Al was crystallized from the liquid phase of the Al--Sn film, for example, 400.
By heating to ℃, A in the Al film formed above
Al diffused into Sn-Al, which is a liquid phase, and was previously filled in the connection hole and the wiring groove and held in the liquid phase.
In the inside, the supplied Al is crystallized on the Al layer 45 which has been crystallized in the contact hole and the wiring groove concave portion in a composition amount equal to or higher than the equilibrium concentration at 400 ° C. In this way, the Al crystallized film 45 is filled in the connection hole and the wiring groove recess. Alternatively, Al may be supplied by a method such as sputtering while keeping the Sn—Al alloy in the connection hole and the wiring groove in the liquid phase.

During the step of crystallizing Al from the liquid phase Sn film or the liquid phase Al—Sn film performed while supplying Al, or after the step of crystallizing Al of Al, the temperature is lowered to crystallize Al. You can go. Further, in the Al crystallization process by the temperature decrease, the temperature may be decreased several times during the Al supply process.

After that, the film in which Sn is deposited outside the connection hole and the wiring groove and the Al film which is the conductive film are removed by etching back by RIE, CMP or the like to form the connection plug and the groove wiring 45 (FIG. 12B. )).

In this embodiment, after the step of filling the Al—Sn film into the connection hole and the wiring groove recess before the Al film formation, the step of removing the Al—Sn outside the connection hole and the wiring groove recess was carried out. The step of removing the native oxide film on the surface of the Al—Sn and the step of depositing the Al film may be performed without removing the Al—Sn outside the hole and the recess of the wiring groove.

Embodiment 7 With reference to FIGS. 1 and 2, a connection plug and groove wiring forming process according to this embodiment will be described.

By the various methods already mentioned, Al--S
A liquid phase alloy 6 made of an n alloy is formed at least in the connection hole and the wiring groove (FIG. 1B). After that, Al and Sn
Under the condition that a sufficient etching selection ratio can be obtained, while flowing a gas containing Cl ₂ gas in a heated state, or exposing the Al-Sn film surface to Cl ₂ gas plasma or radicals. By doing so, only Sn is removed. By doing so, the Sn concentration in the molten AlSn alloy was lowered, the equilibrium state concentration was relatively shifted, and Al was crystallized. It is also possible to combine this with a liquid phase temperature lowering process to chloride and remove Sn to concentrate the Al-Sn liquid phase alloy.

After that, as in the method of the other embodiments, the excess Sn outside the connection hole and the wiring groove and the Al—Sn alloy were removed to form an Al crystallized film in the connection hole and the wiring groove. .

At this time, before performing Cl ₂ flow, Al
-By heating the oxide film on the surface of the Sn film in an atmosphere having hydrogen or a reducing action, or by removing it by a method such as sputtering, Al can be more effectively
It was possible to remove the Sn film.

Example 8 With reference to FIGS. 13 and 14, a connection plug and groove wiring forming process according to this example will be described.

First, a first wiring layer 52 is formed on a silicon substrate (not shown) on which elements are formed, and then an interlayer insulating film 53 is formed thereon. Then, a TiN film 59 is formed on the inter-layer insulating film 53, and the inter-layer insulating film 53 is subjected to a first photolithography process and an RIE process.
A connection hole 54 and a wiring groove 55 connected to the wiring layer 52 are formed (FIG. 13A).

The natural oxide film on the first wiring layer 52 exposed at the bottom of the connection hole 54 is removed by surface treatment such as reverse sputtering. Next, the connection hole 54 and the wiring groove 5
5 is filled with the Sn film 56. After that, Sn outside the connection hole and the wiring groove is removed by RIE, CDE, or CMP (FIG. 13B).

Next, after removing the natural oxide film on the surface of the Sn film, the Al film 5 containing no impurities is maintained while the vacuum is maintained.
Form 7. (FIG.13 (c)). By heat-treating this sample at a temperature at which Sn becomes a liquid phase, for example, 450 ° C., Al diffuses into the Sn film which is a liquid phase, and Sn diffuses into the upper Al film. , Connection hole 54
And the Al layer 58 is formed in the wiring groove 55 (FIG. 13).
(D)).

After that, the film in which Sn is deposited and the Al film which is the conductive film outside the connection hole 54 and the wiring groove 55 are removed by R
It is removed by etch back by IE, CMP, or the like (FIG. 14A).

Next, a Cu film 60a is deposited on the entire surface, and heat treatment is performed at 300 ° C. for 30 minutes, for example.
Is added (FIG. 14 (b)). After that, the Cu film and the TiN film outside the connection hole 54 and the wiring groove 55 are removed by etching back by RIE, CMP or the like to form the connection plug and the groove wiring 60b (FIG. 14C).

Cu in the Al wiring is an additive element for improving electromigration and stress migration resistance, and is generally added to the Al wiring in the LSI and used as a wiring material. However, at the same time, it is an element that forms a stable compound with Sn. When the liquid phase Sn is held in the connection hole or the wiring groove and Sl is diffused to crystallize in the connection hole or the wiring groove, if an Al film containing Cu is used in the Al supply step, the crystallized Al is crystallized.
Cu forms a compound with Sn, and 2 of Al and Sn
This may make it difficult to cause layer separation. That is, a high-resistance film containing a large amount of Sn is formed.

Therefore, in the present embodiment, Al that does not contain impurities is used as Al to be crystallized in the liquid Al—Sn film to crystallize the Al film in the connection hole and the wiring groove. After the formation, the step of adding Cu into the wiring is performed in order to improve the reliability of the wiring. As a result, it is possible to form a connection plug and a groove wiring with low resistance and high reliability.

Embodiment 9 In the above embodiment, the method of obtaining the liquid phase by heating after forming or filling the initial connection hole and the wiring groove of the Al—Sn film or the Sn film by only the sputtering method has been described. ,
In this liquid phase filling step, an example of steps in which the pressure heat treatment is performed while applying uniaxial stress will be described.

First, an example of applying uniaxial stress will be described with reference to FIG.

After the lower layer structure of the element and the lower layer wiring are formed on the Si substrate 61, insulating films 62a and 62b are formed on both surfaces thereof, and a connection hole and a wiring groove are formed in one insulating film 62a. The reason why the insulating film is formed also on the back surface of the Si substrate 61 is to prevent Sn from diffusing to the substrate side in the subsequent steps, and not only the insulating film but also a barrier film. Any film may be used.

Next, as shown in FIG. 15A, the molten Al—Sn alloy or Sn bath 63 contained in the crucible 64.
The Si substrate 61 is placed on the wafer support base 65 so that the entire substrate is immersed therein. In the figure, reference numeral 66 indicates a heater. Next, the Si substrate 61 is pulled up from the bath 63, and is mounted / installed on a wafer mounting table 67 equipped with heating / cooling means, as shown in FIG. At this time, the Al—Sn alloy film 68 is formed on the insulating film 62 a of the Si substrate 61. Al-Sn alloy film 68 of Si substrate 61
A heater 70 having a quartz jig 69 whose inner diameter is the same as the diameter of the Si substrate 61 is installed facing each other.

Next, as shown in FIG. 15C, the heater 70 is lowered to be in close contact with the Si substrate 61, and the heaters above and below the substrate, that is, the heater 70 and the wafer mounting table, are applied while applying pressure. Only the heater 67 or the heater 70 is heated to obtain the molten Al-Sn alloy or the molten Sn. Then, the upper and lower heaters are cooled, or only the heater of the wafer mounting table 67 is cooled to crystallize Al.

After that, the heater of the wafer mounting table 67 is cooled to form an Al crystalline plug, and then the Al--Sn alloy film or Sn film outside the connection hole and the wiring groove is treated with Cl in the same manner as in the above embodiment. _It is removed by a flow of a gas containing ₂ gas, RIE, etch back by CDE, or CMP. The barrier film on the back surface is removed by polishing the back surface, wet etching, or the like after the wiring step or after each step.

Example 10 With reference to FIG. 16, an example of steps using the liquid phase filling method by applying uniaxial stress is shown.

As shown in FIG. 16A, the exhaust mechanism 73
An apparatus in which a crucible 76 containing an Al—Sn alloy or a Sn bath 75 is installed in a chamber 74 equipped with is used. Wafer support inside the apparatus is performed by a wafer mounting table 77 and a cooling mechanism 78 on the back surface of the substrate, and the substrate 71 can be moved in and out of the crucible 76 by vertical movement.

The Si substrate 71 is introduced into this apparatus and placed on the wafer mounting table 77. In addition, the Si substrate 71 is
After the lower layer structure and the lower layer wiring of the element are formed, insulating films 72a and 72b are formed on both surfaces thereof, and a connection hole and a wiring groove are formed in one insulating film 72a. Note that Si
The reason why the insulating film is formed also on the back surface of the substrate 61 is to prevent Sn from diffusing to the substrate side in the subsequent process, and not only the insulating film but also a film functioning as a barrier film may be used. Good.

After sufficiently vacuuming the inside of the chamber 74, a crucible 76 containing the AlSn alloy or the Sn bath 75.
The wafer mounting table 77 and the cooling mechanism 78 are lowered inside, and the entire surface of the connection hole and the wiring groove is immersed in the bath 75. In this state, an inert gas Ar or N ₂ is introduced into the chamber 74 to pressurize the chamber 74 to atmospheric pressure or higher. Thereby, as shown in FIG. 16B, uniaxial stress is applied to the surface of the bath 75.

As a result, the melted A
The 1-Sn alloy or Sn can be embedded. With this stress applied, the substrate 71 is cooled by the substrate cooling mechanism 78 while gradually pulling up the substrate 71.
Thus, the Al crystallized film 79 is formed in the connection hole and the wiring groove.

After that, Al- outside the connection hole and the wiring groove is
The Sn alloy film or the Sn film was replaced with C as in the above-mentioned embodiment.
It is removed by a flow of a gas containing l ₂ , etching back by RIE or CDE, or CMP. The barrier film on the back surface is formed after the wiring process or after each process.
The back surface is removed by polishing, wet etching or the like.

According to this technique, the Al--Sn film is more stably heated during heating than the burying of the Al--Sn film only by sputtering.
The liquid phase of the Al—Sn film can be retained in the connection hole or the wiring groove, and the Al crystallized film can be formed in the connection hole or the wiring groove.

The combination of the methods shown in FIGS. 15 and 16 in the ninth and tenth embodiments is not particularly limited to this. For example, after Sn is embedded by the method shown in FIG. It is also possible to crystallize Al by bringing Al deposited in the quartz jig 69 shown in b) into contact with Sn embedded in the connection hole and the wiring groove, and applying stress and heating.

Example 11 Al-Sn alloy was deposited, or Al-Sn was deposited in the fine connection holes and wiring grooves during the temperature rising process after deposition of the Al-Sn film.
As a means for realizing more stable filling of the Sn alloy, in addition to the uniaxial stress application shown in Examples 9 and 10, there is a method of utilizing the capillary effect of the fine connection holes and the capillary electric effect. This method is shown below.

After forming the lower wiring on the Si substrate, an interlayer insulating film is formed. Next, a connection hole and a wiring groove are formed in the interlayer insulating film. Similar to the above-described example, an Al—Sn alloy was deposited on the Si substrate and embedded so as to reach the bottom of the connection hole. Next, when the temperature of this sample was raised until a liquid phase was obtained, it was possible to fill and retain the Al—Sn alloy by the capillary effect. Under this condition, the temperature was lowered and kept at a constant temperature to crystallize a plug whose main component was Al.

Further, at the time of heating and heating this sample, at the same time, this substrate is subjected to an ion shower or is irradiated with electrons at a low energy to bias the substrate to form Al-
Sn ²⁺ in the Sn alloy is increased and temporarily retained on the Al-Sn alloy. At this time, the substrate is kept insulated from the entire device. As a result, the surface energy of the Al-Sn alloy decreases, and Al-Sn
The n alloy was filled and held in a more uniform state without voids, and the Al crystallized plug from the liquid phase could be formed more effectively in this state.

To create such a state similarly, A
After depositing the 1-Sn alloy and burying it so as to reach the bottom of the connection hole, the sample was electrically insulated and held in a strong magnetic field to generate an eddy current and to temporarily charge the surface. A similar effect can be obtained by holding and holding.

Example 12 Next, as a method for improving the wettability of a liquid phase metal or a liquid phase alloy, a method of modifying the surface of an oxide film for forming a pattern will be described with reference to FIG.

As shown in FIG. 17A, the lower wiring layer 8
2 and the oxide film 83 are formed, then Ar, He, Ne, and Xe inert gas ions are formed on the entire surface of the substrate (not shown) in which the connection holes 84 and the wiring grooves 85 are formed by a low acceleration ion implantation method. Type one or more types (Fig. 1
7 (b)). It is sufficient that this ion implantation can reach the surface of the oxide film 83 and the inner wall of the connection hole 84.
For example, if the connection hole has an aspect ratio of 10 and a diameter of 0.1 μm, the ions are made incident at a tilt angle of θ = tan ⁻¹ (0.1) so that the ions are sufficiently made incident on the inner wall of the connection hole 84. . It should be noted that the Rp of the incident ions is 1 to the surface of the oxide film 83.
It is even more effective if the incident energy is set low so as to be 2 nm.

Thus, the Si--O on the surface of the oxide film is
By breaking the bond, the surface of Sn or Al-Sn
It should be in a state where it is likely to cause an interface reaction with the liquid phase of the alloy.

In this state, an Al--Sn alloy is deposited by a method such as sputtering and the substrate is heated to obtain a liquid phase of the Al--Sn alloy. Alternatively, while heating the substrate, Al
-Sn alloy is sputtered to obtain a liquid phase. At this time, the surface reaction layer 86 is formed at the interface between the surface of the oxide film and the Al—Sn alloy, and the wettability with the surface reaction layer 86 is utilized to make use of the liquid phase Al—Sn alloy or Sn single crystal. The layer film 87 was embedded up to the bottom of the connection hole (FIG. 17C).

Example 13 Example 13 will be described with reference to FIG.

A lower Al wiring layer 9 is formed on the substrate (not shown).
After forming 2a, Ti / TiN laminated films 92b and 92c were deposited as barrier metals, and then a SiO ₂ film 93 was deposited as an interlayer insulating film. Next, low acceleration ion implantation using a gas mainly containing Cl ₂ , reverse sputtering, RIE, or the like was performed on the surface of the interlayer insulating film 93 (FIG. 18A). Thus, the entire surface of the interlayer insulating film 93 is terminated with chlorine or chlorine is adsorbed (see FIG. 18).
(B)).

After that, the connection hole 94 and the wiring groove 95 are formed by the usual lithography process and etching (FIG. 18C). Next, the Sn film or the Al—Sn film is embedded in the connection hole and the wiring groove. At this time, the surface of the interlayer insulating film 93 is likely to form Sn chloride having a high vapor pressure, and Sn and the Al—Sn alloy are not easily adsorbed. And wiring groove 95
Sn and Al-Sn easily enter the inside, and Sn
When the film and AlSn film are deposited or when a liquid phase is obtained by heating, the Sn film and the A film are more effectively formed in the connection hole and the wiring groove.
An Isn film could be formed.

Example 14 In the above-mentioned examples, Al--S was formed in the connection hole and the wiring groove.
In the step of filling the n film and the Sn film, or Al-S
In the Al crystallization process by heating and maintaining a constant temperature of n alloy,
As a structure for more stably holding the Al—Sn alloy in the connection hole and the wiring groove, the connection hole bottom has a liquid phase of Al—Sn.
It is desirable that a material having good wettability is exposed to the film and the Sn film. As a result, a liquid phase of Al-Sn can be efficiently formed in the connection hole or the wiring groove, and the final Al crystallized filling shape becomes good.

At the time of opening the connection hole, the silicide film on the lower layer wiring or the pn junction is formed so as to be exposed, and the barrier metal of the lower layer wiring or the surface of the antireflection film for lithography processing is exposed. Form a hole.
Alternatively, after forming the connection hole and the wiring groove, a barrier metal or a base film for improving wettability is formed in the concave portion of the connection hole and the wiring groove.

The film used at this time is a SiO ₂ film (surface energy: 605 erg / g) if it is an amorphous film.
cm ² ), the surface energy of which is higher than, for example, T
a (surface energy: 2130 erg / cm ² ), Ni
₆₂ -Nb ₃₈ (surface energy: 1326 erg / c
m ² ), Ta- ₆₀ % at% Al (surface energy: 16
40 erg / cm ² ) and the like. Also,
TiN, TiC, TiB, TiB ₂ , TiSi ₂ , Zr
Nitride such as N, ZrC, and ZrSi ₂ , a carbonized product, and a silicide are also effective because they have high surface energy. In the case of trench wiring, it is desirable that the above film is formed only by anisotropic sputtering on the bottom of the wiring. In the case of trench wiring with a large hole diameter and groove wiring with a large line width, in the connection hole, the trench The film may be formed on at least a part of the inside.

In the base structure of the present embodiment, VC, TiC, and
A structure for exposing TiB ₂ , AlB ₂ , ZrC, NbC and W ₂ C is added.

Further, the above-mentioned film is formed by sputtering using a sputtering target made of the above-mentioned element, and in the case of carbide and boride, V, T is used as the base.
After depositing i, Al, Zr, Nb, and W, or after opening a connection hole, ion implantation of C and B is performed, and then annealing is performed to perform surface modification, and carbide and boride of the surface layer are formed. Forming an alloy film was also effective.

Further, the compound film is listed as the film type, but the film type is not limited to this, and each film may be a single film.

Example 15 Next, FIG. 19 shows an example relating to the Al crystallization step.
Will be described with reference to.

In Example 1 above, at the point of (a) in FIG.
The liquid phase of the Sn alloy is acquired, and the solid-liquid two-phase region (d) point,
For example, the temperature was lowered to 350 ° C. and kept at a constant temperature, and finally to a temperature just above the eutectic temperature. However, the temperature was once lowered to a point (b) immediately above the eutectic line above 228 ° C. Finally, even if the temperature was lowered to point (c) to obtain a solid phase, good Al crystallization and embedding characteristics were exhibited.

In the Al crystallization process, the temperature is lowered or Sn is used.
Due to the selective etching, etc., a deviation from the equilibrium concentration in the liquid phase occurs, and the difference in the equilibrium concentration causes Al to crystallize.
Table 1 shows the equilibrium concentrations of Al and Sn at each temperature.
The same applies to other materials such as Cu and Bi, and Table 2 shows the equilibrium concentrations of Cu and Bi at each temperature.

[0140]

[Table 1]

[0141]

[Table 2]

Further, in the step of lowering the temperature to below the eutectic temperature, the step of lowering and holding the temperature is not limited to one temperature, and a secondary or higher order, lowering temperature and holding step can be performed. Moreover, the temperature lowering step and the holding step are not necessarily 1
It is also possible to gradually cool from the liquid phase instead of the pair 1.

[0143] Further, until the temperature immediately above the eutectic temperature is reached, the temperature is lowered, the temperature is kept constant and the temperature is raised (in the solid-liquid two-phase coexistence region).
-Even when the temperature lowering / constant temperature holding was repeated a plurality of times, similarly good embedding characteristics were exhibited. Further, the cooling rate for cooling to a certain point (d) in the solid-liquid two-phase region is set to R1, (d).
Let R2 be the rate of temperature decrease from point B to point B
>> In the case of R2 (when R1 is rapidly cooled), R1 to R2 (R
When both 1 and R2 are rapidly cooled or both are slowly cooled),
All of them showed good Al burying characteristics with less voids and less variation in film thickness than the conventional method.

Embodiment 16 An embodiment relating to the deposition and heating process of the Al—Sn film or Sn film in the above embodiment will be described with reference to FIG.

In FIG. 20A, the Si substrate 101 is placed on the heating / cooling means 102, and the infrared lamp 103 is arranged above the Si substrate 101.

When initial Al—Sn alloy or Sn is deposited on the oxide film having the connection hole and the wiring groove formed on the Si substrate 101, first, from the bottom side of the connection hole to the front side direction, A downward slope of temperature is created. Board 10
From the back surface of No. 1, Al-Sn alloy or Sn is sputtered directly while being heated by the heating / cooling means 102.
At this time, the temperature is equal to or higher than the temperature at which the liquid phase in the composition of the film being sputtered is obtained (283 ° C. or higher for the Sn film).
In addition, while heating the substrate 101, film formation is performed at a deposition rate such that the liquid-phase metal film thickness a deposited on the connection hole and the wiring groove and the liquid-phase metal film thickness b deposited on the sidewall of the connection hole are approximately a <b. (FIG.20 (b)).

After embedding the Al—Sn alloy or Sn, while heating the surface of the substrate to the liquidus temperature or higher, the temperature from the back surface to a temperature above the eutectic temperature of 288 ° C.
Cooling is performed using the heating / cooling means 102, and the connection hole is
While maintaining the temperature gradient opposite to that during the initial metal deposition,
Crystallization is performed.

Regarding the means for generating these temperature gradients, in the above-mentioned embodiment, the substrate heating at the time of depositing the AlSn alloy or Sn metal which is the initial metal phase is carried out by heating / cooling means 102 directly from the back surface. However, the electrode pad is pulled out from the Al wiring of the lower layer,
It is also effective to create a particularly high state at the bottom of the connection hole by arranging it in a susceptor capable of conducting electricity or conducting heat directly and using the lower layer Al as a heating element.

Alternatively, as shown in FIG. 20 (b), the substrate is irradiated from the surface with an infrared lamp 103 to form SiO.sub.2.
Infrared ₂ transmits infrared rays and heat is absorbed only in the wiring immediately below, so it is also effective to use the lower layer Al wiring as a heating element to selectively raise the temperature of the opening of the connection hole and promote the burying. Further, for the heating in the Al crystallization process, it is also effective to directly heat the upper deposited film with an infrared lamp to raise the temperature on the surface side.

The series of heat treatments may be carried out in a high vacuum chamber, or SiH ₄ , S.
It is more effective even when performed in a reducing atmosphere containing iH ₂ , hydrogen and the like. Furthermore, it is also effective to carry out the film formation and the heat treatment in a continuous process and convey them without exposing them to the atmosphere.

Embodiment 17 With reference to FIG. 1, a description will be given of a connection plug and groove wiring forming process according to this embodiment.

First, a first wiring layer 2 is formed on a silicon substrate (not shown) on which elements are formed, and then an interlayer insulating film 3 is formed thereon. Then, a first photolithography process and an RIE process are performed on the interlayer insulating film 3 to form a first film.
The connection hole 4 and the wiring groove 5 connected to the wiring layer 2 are formed (FIG. 1A).

The natural oxide film on the first wiring layer 2 exposed at the bottom of the connection hole 4 is removed by surface treatment such as reverse sputtering. Next, Cu is applied to the connection hole 4 and the wiring groove 5 by using directional sputtering, for example, collimation sputtering, low pressure-long distance sputtering, or the like.
-Form Bi. At this time, the substrate is heated to Cu-Bi.
May be fluidized and filled in the connection hole and the wiring groove. Alternatively, the filling with the liquid phase as used in the above-described embodiment or the filling with the liquid phase + pressurization may be performed (FIG. 1).
(B)).

Next, the substrate is heated to form the Cu--
A liquid phase of Bi alloy is obtained. This liquid phase Cu-Bi alloy is solid-
By lowering the temperature to the liquid two-phase region or moving the equilibrium concentration by selectively removing Bi, the Cu film that is excessive from the equilibrium concentration is crystallized in the liquid phase on the insulating film, and the connection is made. A Cu crystallized film is formed in the hole and the wiring groove. Here, the crystallized film of Cu has a Bi concentration equal to or lower than the maximum concentration at which the crystallized Cu and the liquid phase Bi are in equilibrium when the liquid phase of the Cu-Bi film is formed in the connection hole or the wiring groove. It is a value containing Cu as a main component contained in the Cu crystallized film.

Subsequently, Bi outside the connection hole and the wiring groove is
The film, the Bi—Cu alloy, and the Cu film are removed by etching back by RIE, CMP, or the like to form a connection plug and a groove wiring.

Embodiment 18 Next, with reference to FIG. 21, a description will be given of a connection plug and groove wiring forming process according to this embodiment.

By the various methods of the above embodiment, WB
The molten metal film 113 made of i is embedded in the connection hole and the wiring groove, and the W film 114 is thinly crystallized in the connection hole and the wiring groove (FIG. 21A). Excess Bi is removed by RIE using a gas containing chlorine in the same manner as in the above-described embodiment to expose the W film 114, and then N ₂ or NH _{3 is} added.
The WN _x film 115 is formed by placing it in a chamber into which a gas can be introduced and nitriding the surface of the W film 114 by annealing, plasma nitriding, high pressure nitriding, or annealing after N ₂ ion implantation (FIG. 21). (B)).

Again, the molten alloy 116a made of Cu--Bi was embedded in the connection hole and the wiring groove of this sample, and the WN
_{On the x} film 115, as in the above-described embodiment, Cu116b
Are crystallized to form a Cu crystallized plug covered with the WN _x barrier metal film 115 (FIG. 21C). Then, as in the above-described embodiment, a gas containing Cl ₂ , Br ₂ , or F ₂ is used to perform etch-back by RIE or CDE, or by CMP, excess Cu—Bi outside the recesses of the connection hole and the wiring groove is formed. , Bi, and Cu are removed.

Example 19 With reference to FIG. 21 used in Example 18, a connection plug and groove wiring forming process according to this example will be described.

By the various methods shown in the above embodiments,
The molten metal film 113 made of W-Ge is thinly coated in the connection hole and the wiring groove to thinly crystallize the W film 114 (FIG. 2).
1 (a)). By the same method as the above embodiment, Ge
After exposing the W film 114 containing Si or a laminated film of Ge / W films, it is placed in a chamber into which N ₂ or NH ₃ gas can be introduced, and the surface of the W film 114 is nitrided by annealing.
The WN film and the W-Ge-N film 115 are formed by any one of plasma nitriding, high-pressure nitriding, and annealing after N ₂ ion implantation (FIG. 21B).

Further, a molten alloy 116a made of Cu-Bi was embedded in the connection hole and the wiring groove of this sample, and WN
On the film 115, Cu116b was crystallized to form the WN film or the WGeN barrier metal film 115 in the same manner as in the above-mentioned embodiment.
Forming a Cu crystallized plug coated on the surface (FIG. 21).
(C)). Then, as in the above-mentioned embodiment, Cl ₂ , B
RIE or CDE with a gas containing r ₂ or F ₂
Excess Cu-Bi, Bi, and C outside the concave portion of the connection hole and the wiring groove by CMP or by CMP.
Remove u.

Embodiment 20 With reference to FIG. 22, a connection plug and groove wiring forming process according to this embodiment will be described.

A barrier metal such as WN or WSiN film 120 is formed in the connection hole and the wiring groove by CVD or the like.
To form. Next, the molten metal film 121 made of W-Cu-Bi is embedded in the connection hole and the wiring groove by the various methods shown in the above-described embodiment (FIG. 22A). By lowering the temperature from the molten state of the molten metal film 121,
W is crystallized on the WN film 120 first, and then Cu is crystallized, so that WN or WSi which is a barrier metal is crystallized.
An N film 122 and a Cu film 123 with good adhesion are formed.

After forming the Cu crystallized plug in this way,
Similar to the above-described embodiment, a gas containing Cl ₂ , Br ₂ , or F ₂ is used to perform etch-back by RIE or CDE, or by CMP, excess Cu—Bi, Bi outside the concave portion of the connection hole and the wiring groove is formed. , And Cu are removed.

Embodiment 21 With reference to FIG. 23, a process of forming a connection plug and a groove wiring according to this embodiment will be described.

The STl oxide film 13 is formed on the Si semiconductor substrate 131.
2, gate electrode 133, and 1 formed on the side wall thereof
An impurity diffusion layer 134 is formed by a well-known ion implantation method on a structure including a SiN film 133e having a thickness of 50 nm and having a silicon surface exposed by being surrounded by the SiN film 133e. Then, by CVD, the B-doped epi-Si film 1 is formed.
After selectively depositing 35 and further depositing a Ti / TiN film, a TiSi ₂ film 136 is formed by an RTA process.

After that, Si residue, Ti and TiN are removed by R
It is removed by the IE process, and the salicide and the TiN film 137 are left only on the diffusion layer. Then, by CVD, Si
The interlayer insulating film 138a made of O ₂ / BPSG has a thickness of 1.2 μm.
Then, the interlayer insulating film is flattened by CMP and a connection hole is opened (FIG. 23A).

Then, similarly to the above-mentioned embodiment, Al--S
Al crystallized plug 1 embedded with n alloy and heat-treated
39a is formed. Next, excess S outside the connection holes and wiring grooves
The n layer, Al layer, and Al—Sn layer are removed by a method such as CMP. In addition, the excess Sn layer outside the connection hole and the wiring groove, A
After removing the 1-layer and the Al—Sn layer, reduction heat treatment is performed in a reducing atmosphere to improve the bonding characteristics of the contact portion.
It is even more effective.

Next, an interlayer insulating film is deposited to a thickness of about 1 μm, planarized again by CMP, and then a groove for filling the wiring of the first layer is formed. Then, a Ti / Ti nitride laminated film 140a which is a barrier metal is formed in this groove, the surface of the TiN film is stuffed by exposing it to an oxidizing atmosphere, and a Cu film 160 of 0.3 μm is formed thereon by sputtering.
Embed the thickness of.

CMP was applied to the surface, and Cu was formed only in the groove.
Cu is removed from the oxide film, leaving the wiring. After the Ti / TiN laminated film 140b, which is a barrier metal, is deposited thereon again, the excess Ti / TiN laminated film on the insulating film is removed, and the interlayer insulating film 138b is further deposited thereon. A connection hole is again formed in the interlayer insulating film 138b, and an Al crystallized plug 139 is formed in the connection hole in the same manner as in the above-described embodiment.
b is formed.

Hereinafter, the wiring is formed of an Al crystallized plug by crystallization from a molten metal using a material mainly containing Cu and the plug is an Al—Sn alloy or the like to form a multilayer wiring (FIG. 23 ( c)). As a result, it is easy to secure the barrier property of the barrier metal in the connection hole, which is difficult in forming the Cu plug, by using the Al plug crystallized from the molten Al—Sn alloy, which leads to problems of low resistance and reliability. By forming the wiring portion formed of Cu with Cu, a highly reliable wiring can be formed by a relatively easy process.

Further, in the present embodiment, the Cu wiring has a structure in which the periphery is surrounded by a barrier metal, but it is also possible to form the barrier metal by using an insulating film in which Cu does not diffuse.

In the embodiments described above, the combination of materials is not limited to the binary alloy, but it is of course possible to use an alloy of three or more elements. Although the Al-Sn system has been mainly described in the above embodiments, the material is not limited to this. In the binary alloy applicable to the present invention, specifically, when the filling material is Al, the low melting point metals to be combined are Ga and H in addition to Sn in the above embodiment.
g, Ge, if the filling material is Cu, the low melting point metal to be combined is Bi; if the filling material is silver, the low melting point metal to be combined is Tl; if the filling material is W, Hg, Ga, Ge. , Bi, Pr, Pu are combined with the low melting point metal when the filling material is Si, Z is
n, Sb, In, Cd, Ag, Sn, and Al can be applied. Further, Ge and SiGe can be substituted for Si, and the low melting point metal that can be combined at this time can be the same as that for Si.

Furthermore, although the above embodiments have described the formation of the connection plug and the groove wiring, the wiring may be formed by RIE without using the present invention, and this may be combined with the connection plug formed by the present invention. Of course it is possible.
Furthermore, in the above examples, Examples 8, 17, 18, 1
Al films other than 9 and 20 are Al alloy films such as Al-C.
It is also possible to use u or Al-Si-Cu.

In the present specification, the term “liquid phase” means not only the state of a metal melted by heating, but also the solid-liquid two-phase coexistence in which the equilibrium concentration shifts to start crystallization of the conductive film. The state is also shown. In the above examples, it is essential that the conductive film is crystallized from the state of the liquid phase sufficiently exceeding the liquidus line while maintaining the region of solid-liquid two-phase coexistence and coexistence with the liquid phase.

The above embodiments are not limited to these, and it is of course possible to carry out various combinations.

[0177]

As described in detail above, according to the present invention,
It is possible to easily form plugs and wirings in which the main wiring materials Al, Cu, Ag, Si, and W are satisfactorily embedded at a very low process temperature without the need for an underlying adhesion layer.

[Brief description of drawings]

FIG. 1 is a sectional view showing a process of forming a connection plug and a groove wiring according to a first embodiment of the present invention in the order of steps.

2A to 2D are cross-sectional views showing a connection plug and groove wiring formation process according to the first embodiment of the present invention in the order of steps.

FIG. 3 is a cross-sectional view showing a process of forming a connection plug and a groove wiring according to a third embodiment of the present invention in the order of steps.

FIG. 4 is a cross-sectional view showing a process of forming a connection plug and a groove wiring according to a third embodiment of the present invention in the order of steps.

FIG. 5 is a sectional view showing a process of forming a connection plug and a groove wiring according to a fourth embodiment of the present invention in the order of steps.

FIG. 6 is a cross-sectional view showing a process of forming a connection plug and a groove wiring according to a fourth embodiment of the present invention in the order of steps.

FIG. 7 is a cross-sectional view showing a step of forming a connection plug and a groove wiring according to the fifth embodiment of the present invention.

FIG. 8 is a sectional view showing a process of forming a connection plug and a groove wiring according to a fifth embodiment of the present invention in the order of steps.

FIG. 9 is a sectional view showing a process of forming a connection plug and a groove wiring according to a modification of the fifth embodiment of the present invention in the order of steps.

FIG. 10 is a sectional view showing a process of forming a connection plug and a groove wiring according to a modification of the fifth embodiment of the present invention in the order of steps.

FIG. 11 is a sectional view showing a process of forming a connection plug and a groove wiring according to the sixth embodiment of the present invention in the order of steps.

FIG. 12 is a cross-sectional view showing a process of forming a connection plug and a groove wiring according to the sixth embodiment of the present invention in the order of steps.

FIG. 13 is a cross-sectional view showing the process of forming a connection plug and a groove wiring according to the eighth embodiment of the present invention in the order of steps.

FIG. 14 is a cross-sectional view showing a process of forming a connection plug and a groove wiring according to the eighth embodiment of the present invention in the order of steps.

FIG. 15 is a view for explaining the process of forming the connection plug and the groove wiring according to the ninth embodiment of the present invention.

FIG. 16 is a view for explaining the process of forming the connection plug and the groove wiring according to the tenth embodiment of the present invention.

FIG. 17 is a cross-sectional view showing the process of forming a connection plug and a groove wiring according to the twelfth embodiment of the present invention in the order of steps.

FIG. 18 is a cross-sectional view showing the step of forming a connection plug and a groove wiring according to the thirteenth embodiment of the present invention.

FIG. 19 is a state diagram of Al—Sn.

FIG. 20 is a view for explaining the process of forming the connection plug and the groove wiring according to the sixteenth embodiment of the present invention.

FIG. 21 is a view for explaining the process of forming the connection plug and the groove wiring according to the eighteenth embodiment of the present invention.

FIG. 22 is a view for explaining the process of forming the connection plug and the groove wiring according to the twentieth embodiment of the present invention.

FIG. 23 is a view for explaining the process of forming the connection plug and the groove wiring according to the twenty-first embodiment of the present invention.

FIG. 24 is a cross-sectional view showing a dual damascene structure formed by a reflow film forming method in a conventional multilayer wiring portion.

FIG. 25 is a cross-sectional view showing the process of forming a conventional connection plug in the order of steps.

[Explanation of symbols]

2, 12, 22, 32, 42, 52, 82, 92, 13
2, ... First wirings 3, 13, 23, 33, 43, 53, 83, 93 ... Interlayer insulating films 4, 14, 24, 34, 44, 54, 84, 94 ... Connection holes 5, 15, 25, 35, 45, 55, 85, 95 ... Wiring groove

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Nobuo Hayasaka, No. 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa, Toshiba Research & Development Center Co., Ltd. (72) Inventor Junichi Wada Komukai-shiba, Kawasaki-shi, Kanagawa No. 1 in Toshiba R & D Center Co., Ltd. (72) Inventor Katsuya Okumura No. 1 Komukai Toshiba-cho, Kouki-ku, Kawasaki-shi, Kanagawa Within Toshiba R & D Center Co., Ltd. (56) ) JP-A-6-204349 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/288 H01L 21/768

Claims (16)

(57) [Claims] 1. A method comprising: forming an insulating film on a semiconductor substrate; forming a recess in the insulating film; and containing a conductive element and a substance having a melting point lower than that of the conductive element in the recess. A step of forming a liquid phase, the composition of the liquid phase, the conductive element is moved from the equilibrium composition to an excess composition to crystallize the conductive element, at least a conductive film in the recessed portion. A method of manufacturing a semiconductor device, comprising: a forming step; and a step of removing a substance existing on the insulating film outside the recess. 2. The step of forming a liquid phase containing a conductive element and a substance having a melting point lower than that of the conductive element in the recess includes at least the conductive element and the element 2. The method for manufacturing a semiconductor device according to claim 1, further comprising: forming a solid phase alloy layer containing a substance having a low melting point, and then heating and melting the solid phase alloy layer. 3. The step of forming a liquid phase containing a conductive element and a substance having a melting point lower than that of the conductive element in the recess has a melting point lower than that of the conductive element in at least the recess. Forming a substance layer having, forming the conductive element layer, heating and melting a substance layer having a melting point lower than that of the conductive element, and diffusing the conductive element in the melt. The method for manufacturing a semiconductor device according to claim 1, wherein: 4. The step of forming a liquid phase containing a conductive element and a substance having a melting point lower than this element in the recess has a melting point lower than that of the conductive element at least in the recess. And forming a substance layer having the same, heating the substance layer having a melting point lower than that of the conductive element to obtain a liquid phase, and supplying the conductive element to the liquid phase. 1. The method for manufacturing a semiconductor device according to 1. 5. The step of forming a liquid phase containing a conductive element and a substance having a melting point lower than this element in the recess has a melting point lower than that of the conductive element in the recess. 3. A method of filling a molten material or a molten material containing the conductive element and a material having a melting point lower than that of the conductive element while pressurizing.
A method of manufacturing a semiconductor device according to item 1. 6. The step of crystallizing the conductive element by moving the composition of the liquid phase from an equilibrium composition to a composition in which the conductive element is excessive, includes cooling the liquid phase or solidifying the conductive element. 2. The method for manufacturing a semiconductor device according to claim 1, further comprising lowering and holding the temperature in a liquid two-phase temperature region. 7. The step of moving the composition of the liquid phase from an equilibrium composition to a composition in which the conductive element is in excess to crystallize the conductive element, wherein the liquid phase has a solid-liquid two-phase temperature. 2. The semiconductor device according to claim 1, wherein the temperature of the liquid phase is maintained and lowered, the temperature of the liquid phase is raised, the conductive element is supplied to the liquid phase, and the temperature of the liquid phase is lowered. Production method. 8. The step of crystallizing the conductive element by moving the composition of the liquid phase from an equilibrium composition to a composition in which the conductive element is excessive is selected from the group consisting of N, O, and H. The method for manufacturing a semiconductor device according to claim 1, further comprising performing heat treatment in an atmosphere containing at least one selected. 9. The step of moving the composition of the liquid phase from an equilibrium composition to a composition in which the conductive element is in excess to crystallize the conductive element, the substance having a low melting point and the gas phase compound are used. The method of manufacturing a semiconductor device according to claim 1, further comprising: performing a heat treatment in an atmosphere for forming a gas, and removing the vapor phase compound. 10. The step of removing a substance existing on the insulating film outside the recess comprises introducing a gas containing halogen to form a halide and removing the halide. 1. The method for manufacturing a semiconductor device according to 1. 11. The method of manufacturing a semiconductor device according to claim 1, wherein the halogen is at least one selected from the group consisting of chlorine, fluorine, iodine, and bromine. 12. A step of forming an insulating film on a semiconductor substrate, a step of forming a recess in the insulating film, a barrier metal or a substance having a surface energy higher than that of the insulating film on at least a part of the inner surface of the recess. A step of forming a thin film made of, a step of forming a liquid phase containing a conductive element and a substance having a melting point lower than this element in the recess, the composition of the liquid phase from the equilibrium composition to the above A step of moving the conductive element to an excessive composition to crystallize the conductive element to form a conductive film in the recess, and removing a substance existing on the insulating film outside the recess. A method of manufacturing a semiconductor device, comprising: 13. A step of forming an insulating film on a semiconductor substrate, a step of forming a recess in the insulating film, a conductive element and a substance having a melting point lower than this element in the recess. A step of forming a liquid phase, and moving the composition of the liquid phase from an equilibrium composition to a composition in which the conductive element is in excess, crystallize the conductive element to form a conductive film in the recess. And a step of removing a substance existing on the insulating film outside the concave portion, wherein the additive element is added during or after crystallization of the conductive element. Manufacturing method. 14. The method of manufacturing a semiconductor device according to claim 13, wherein the conductive element is a single element. 15. The method of manufacturing a semiconductor device according to claim 13, wherein the additive element is an element that improves electromigration or stress migration resistance of the conductive film after crystallization. 16. The method of manufacturing a semiconductor device according to claim 13, wherein the additional element is an element that lowers the solid solubility limit of the low melting point material after crystallization.