JP2002025943A - Substrate film forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate film forming method for filling a recessed part of a substrate where the recessed part such as a groove and a hole for wiring pattern is formed and a barrier layer is formed on the inner surface of the recessed part in the center without the occurrence of seams and voids. SOLUTION: In this substrate film forming method, a film is formed on the surface of a substrate where fine recessed parts of a wiring pattern are formed on the surface, and the barrier layer 6 is formed on the inner face of the recessed part 2. A film is formed by changing active degrees on the sidewall of the recessed part 2 and the barrier layer 6 surface of the base. Thus, a film can be formed (filling of the recessed part) in the center of the recessed part 2 without the occurrence of seams and voids.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for filling a concave portion of a substrate having a fine concave portion such as a trench for a wiring pattern or a hole with a copper (Cu) material or an alloy thereof. The present invention relates to a substrate film forming method.

[0002]

2. Description of the Related Art As the degree of integration of semiconductor devices increases,
As the line width of a wiring pattern becomes narrower (on the order of 0.1 μm), it is required to use a material excellent in electrical resistance, electromigration resistance and the like in place of aluminum instead of a wiring material. In response to this request,
Form a thin film of copper (Cu) or its alloy with high conductivity on the surface of the substrate where the grooves and holes for wiring patterns are formed, and fill the grooves and holes for wiring patterns by chemical mechanical polishing (CMP). Attention has been paid to a method of polishing and removing copper or its alloy.

As shown in FIG. 1A, a conductive layer 101a is formed on a semiconductor substrate 101 on which a semiconductor element is formed, and an insulating film 102 made of SiO ₂ is deposited on the semiconductor substrate W, as shown in FIG. A contact hole 103 and a trench 104 for wiring are formed by lithography and etching technology, and a barrier layer 105 made of TaN or the like is formed on the inner surface of the trench.

Then, as shown in FIG. 1B, by forming a Cu thin film on the surface of the semiconductor substrate W, the contact holes 103 and the grooves 104 of the semiconductor substrate 101 are filled with Cu and the insulating film is formed. Cu film layer 1 on 102
06 is deposited. After that, chemical mechanical polishing (CM
By P), the Cu film layer 106 on the insulating film 102 is removed, and the surface of the Cu film layer 106 filled in the contact holes 103 and the wiring grooves 104 is made substantially flush with the surface of the insulating film 102. . As a result, a wiring composed of the Cu film layer 106 as shown in FIG. 1C is formed.

At present, a wiring pattern formed of Cu or a Cu alloy is formed by plating the surface of a semiconductor substrate W having a contact hole 103 or a groove 104 with Cu or Cu.
An alloy film is formed, and the contact hole 103 and the groove 10 are formed.
Embedding 4 is the mainstream. However, it is said that when the width of the wiring contact hole 103 or the groove 104 becomes narrower, it becomes difficult to perform plating, and the film is replaced with a film of Cu or a Cu alloy by CVD (chemical vapor deposition).

However, CVD of Cu or Cu alloy
In the case of embedding the concave portion 107 of the groove or hole formed on the surface of the substrate as shown in FIGS. , The seam 108 and the void 10
9 occurs.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has a concave portion such as a groove or a hole for a wiring pattern and a thin film layer formed on the inner surface of the concave portion. It is an object of the present invention to provide a substrate film forming method capable of burying the concave portion of a substrate in a central portion thereof without generating a seam or a void.

[0008]

According to the first aspect of the present invention, a fine concave portion for a wiring pattern is formed on the surface, a thin film is formed on the inner surface of the concave portion, and then the concave portion is embedded and filled. In the substrate film forming step, the film is formed by changing the activity of at least the surface of the side wall and the bottom of the thin film or changing the activity of the side wall and the bottom during the burying of the burying material. .

Further, in order to change the activity of the surface of the thin film at the side wall and the bottom of the concave portion of the substrate, a catalyst metal (for example, Au, A
g, Fe, Co, Ni, Ru, Pd, Pt, W, Os,
The bottom portion is catalyzed by irradiating a straight beam to the bottom of the concave portion.

By changing the activity of at least the surface of the side wall and the bottom as described above, the film formation speed from the bottom surface is increased, and the film formation from the side wall surface is eliminated or the film formation speed is reduced. Thus, film formation (embedding of the concave portion) can be performed without generation of a seam or void at the center of the concave portion.

According to a second aspect of the present invention, in the method of forming a substrate according to the first aspect, the method of changing the degree of activity includes the step of reducing the degree of oxidation and / or the degree of reduction of at least the surface of the side wall and the bottom of the recess. The difference is attached.

According to a third aspect of the present invention, in the method of forming a substrate according to the second aspect, first, the entire surface of the thin film is oxidized in order to impart a difference in the degree of oxidation and / or a difference in the degree of reduction to the surface of the thin film. Or reducing, and then reducing or oxidizing only the thin film at the bottom of the concave portion or removing the oxidized or reduced portion at the bottom.

According to the second and third aspects of the present invention, for example, the thin film is a barrier layer for preventing the diffusion of Cu, and by changing the degree of oxidation and reduction on the surface of the barrier layer, For example, in the CVD process, by making a difference in the film growth rate of Cu or Cu alloy, the film formation speed from the bottom surface of the concave portion is increased, and the film formation speed from the side wall surface is reduced, so that the central portion of the concave portion is formed. Film formation (embedding of concave portions) without generation of seams or voids is possible.

For example, when the material of the barrier layer is a TaN-based material, if the surface of TaN is oxidized, an incubation time occurs during the film formation of Cu, and the film is exposed to a film forming gas at the beginning of the film forming process. However, there is a phenomenon that the film grows after a certain period of time without growing the film.
Therefore, if this phenomenon is utilized, the film forming speed from the bottom surface of the concave portion is increased, the film forming speed from the side wall surface is reduced, and the aspect ratio of the concave portion is substantially constant or gradually decreases as the film grows. And film formation (embedding) without generation of seams or voids becomes possible.

According to a fourth aspect of the present invention, there is provided a method of forming a substrate according to the first aspect of the present invention, in which the activity of a thin film or a thin film surface is changed, or the bottom of a concave portion is formed during the burying material deposition. Only at least one of a reducing action, a catalytic action and a reaction promoting action or an atom / molecule for promoting the action is provided.

Further, in order to change the activity of the thin film surface on the side wall and the bottom of the concave portion of the substrate, a catalytic metal (for example, Au, A
g, Fe, Co, Ni, Ru, Pd, Pt, W, Os,
The bottom portion is catalyzed by irradiating a straight beam to the bottom of the concave portion.

As described above, only the bottom of the recess has atoms or molecules that have or promote one of the reducing action, the catalytic action, and the reaction promoting action. Can be formed at a higher speed from the bottom surface.

[0018] The invention according to claim 5 is the invention according to claims 1 to 4.
In the substrate film forming method according to any one of the above, the substance for embedding in the concave portion is copper or copper as a main component, and the thin film is a barrier layer mainly for preventing diffusion of copper. It is characterized by the following.

As described above, since the substance to be embedded in the recess is copper or a material containing copper as a main component and the thin film is mainly a barrier layer for preventing diffusion of copper, the bottom surface of the recess is formed. The rate of film formation from copper or copper as a main component can be increased, the rate of film formation from the side wall surface can be reduced, and film formation without seams or voids at the center of the concave portion can be achieved.

Further, in order to change the activity of the barrier layer surface at the side wall and the bottom of the concave portion of the substrate, a catalyst metal (for example, A
u, Ag, Fe, Co, Ni, Ru, Pd, Pt, W,
By irradiating a straight beam (Os, Ti, Rh) to the bottom of the recess, the bottom is catalyzed.

Further, in order to make the difference in the degree of oxidation and the difference in the degree of reduction on at least the surface of the side wall and the bottom of the concave portion of the substrate, particles having negative electricity are attached only to the bottom of the concave portion, or at least the surface activity is reduced. In order to change the degree, the constituent material of at least the film surface is different between the side wall part and the bottom part of the concave part, or at least the thin film surface constituent material is composed of two or more elements, and the composition ratio is the side wall part and the bottom part of the concave part. In order to make it different or to change the surface activity, a polymer protective film is formed on the entire surface of the recess,
There is also a method of performing anisotropic etching of the base by reactive ion etching (RIE) to form a film while holding the polymer film on the side wall.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. Here, a case is considered in which a barrier layer is formed by sputtering on the inner surface of a concave portion such as a fine groove or hole of a wiring pattern formed on the surface of a substrate. First, immediately before or after the formation of the TaN barrier layer, the surface of the TaN barrier layer is oxidized by flowing an oxidizing gas. This step can be easily coped with immediately before the completion of the film formation by additionally flowing an oxidizing gas, and after forming the barrier layer by providing a separate oxidation step. In this process,
First, the control of the degree of oxidation in which the entire surface is uniformly oxidized is performed by oxidizing gas (for example, O ₂ , O ₃ ,
O-radicals, N ₂ O, etc.) can be easily performed by flowing a predetermined amount and holding for a predetermined time.

Next, the bottom surface of the concave portion is reduced or the oxidized portion is removed. For example, as shown in FIG. 3, an FAB is formed on a substrate 1 having a fine concave portion 2 for a wiring pattern formed on a surface thereof.
This is performed by irradiating the substrate with a neutral parallel beam 4 perpendicularly from a device such as a (Fast Atom Beam) source 3. Since the beam 4 is a neutral particle beam, the beams do not repel each other, and if the irradiation is parallel at the initial stage, the beam proceeds straight as it is and reaches only the bottom surface of the concave portion 2.

In the case of reduction, for example, hydrogen gas is used as the gas 5 supplied to the FAB source 3. Since hydrogen is released from the FAB source 3 in an excited state or a radical state having a high energy level, hydrogen has a high reducing ability. Moreover, as shown in FIG. 4, since the parallel neutral beam 4 goes straight, the hydrogen radicals collide only with the oxide film 6a of the TaN barrier layer 6 at the bottom of the concave portion 2 of the groove or hole. Only the barrier layer 6 is reduced.

When the oxide film 6a of the barrier layer 6 at the bottom of the recess 2 is removed, the energy of the neutral beam 4 is increased to remove the oxide film 6a at the bottom by sputtering. In this case, an inert gas such as an Ar gas may be used as a gas to be supplied to the FAB source 3. However, a reducing gas such as a hydrogen gas is also used, and two gases of reduction and spatter removal are used.
Two effects may be aimed at at the same time.

By changing the degree of oxidation or reduction of the side wall and the bottom in the recess formed on the surface of the substrate 1 as described above, the bottom can reduce or remove the oxide film of the barrier layer 6, so that the culture ( The film formation starts immediately by flowing the film formation gas without the presence of the incubation time.
Since the side wall is oxidized, a culturing time exists at the initial stage of film formation, and the film is not formed, or even if the film is formed, it grows at a low film forming rate.

As described above, the difference between the film forming rate at the bottom and the side wall of the recess 2 is adjusted by adjusting the degree of oxidation and the degree of reduction of the underlying barrier layer 6, as shown in FIGS. 5 (a) to 5 (d). like,
Aspect ratio B / A of concave portion 2 (where A: width of concave portion 2,
B: Depth of the recess 2) is formed at a film forming rate such that the film is formed (embedded) without generation of seams or voids. 5A to 5D, the surface of the barrier layer 6 on the side wall of the recess 2 is oxidized.
There is incubation time, and no film grows on the side wall surface. The culturing time can be adjusted by the degree of oxidation of the surface of the barrier layer 6, and the growth of the film can be almost suppressed for several minutes.

Further, by adding hydrogen atoms to the bottom surface of the concave portion 2 which requires a high film forming speed, the activity of the bottom surface can be increased. Since a difference can be obtained, the film can be selectively grown only from the bottom. In FIG. 5, a mask is provided so that the upper surface of the substrate 1 is not reduced at the time of reduction, and if the mask is removed thereafter, the growth of the Cu film on the upper surface can be suppressed. An increase in the ratio can be prevented.

As shown in FIGS. 6 (a) to 6 (d), the difference between the film formation rate at the bottom and the side wall of the recess 2 is adjusted by adjusting the degree of oxidation and the degree of reduction of the underlying barrier layer 6. A film is formed at a film forming rate at which the aspect ratio B / A of the concave portion 2 (where A: width of the concave portion 2 and B: depth of the concave portion 2) hardly changes or gradually decreases, and seams and voids are formed. Film formation (embedding) can be performed without generation of cracks.

Further, by providing hydrogen atoms to the bottom surface of the concave portion 2, the activity of the bottom surface can be increased. As shown in FIG. 7, the hydrogen atoms are applied as shown in FIG.
By introducing a hydrogen gas as the first gas 17 and irradiating the neutral particle beam 14 of the hydrogen atoms toward the substrate 1, the hydrogen atoms can be provided only on the bottom surface of the concave portion 2. When a Cu metalorganic material gas is introduced as the second gas 20, the Cu metalorganic material gas diffuses evenly in the air and adheres substantially uniformly to the side walls and the bottom of the concave portion on the substrate surface.

In this state, when hydrogen atoms are applied only to the bottom surface of the concave portion 2 as described above, this reaction is, for example, a general Cu-CVD reaction in the next step of Cu-CVD reaction, Cu (hfac) tmvs → Cu (hfac) + tmv
s 2Cu (hfac) → Cu ↓ + Cu (hfac) ₂ is converted to Cu (hfac) tmvs + H → Cu + H (hfa
c) + tmvs, and hydrogen is concentrated only on the bottom, so that the reaction rate can be improved at the bottom (double growth rate according to the above equation), and the nucleation rate can be improved. It can be expected that the Cu film grows extremely rapidly from the bottom.

H (hfac) is an abbreviation for hexafluoroacetylacetone [C ₅ H ₂ O ₂ F ₆ ].

In the apparatus shown in FIG. 3, an atomic / molecular beam of Ar or the like collides from the FAB source 3 to the bottom of the concave portion 2 of the substrate 1 to roughen the bottom surface, thereby forming a nucleation point for film formation. The resulting fine irregularities are formed. Thereby, the recess 2
Greatly reduces the incubation time from the bottom of the substrate, and allows the growth of a Cu film.

Further, by forming a film while irradiating only the bottom of the concave portion 2 of the substrate 1 with electrons, the bottom of the concave portion 2 has a negative potential, and the reduction reaction of Cu at the bottom of the concave portion 2 is promoted.
It is possible to grow a Cu film having a high film forming rate. Also, in order to change the activity of the barrier layer surface at the side wall and the bottom of the recess 2, the constituent materials of the side wall and the bottom barrier layer of the recess 2 are made different. For example, in the apparatus shown in FIG. 3, by irradiating the organic metal raw material gas of Cu only from the FAB source 3 to the bottom of the recess 2 and attaching it, a Cu film can be grown from the bottom of the recess 2 at a high deposition rate. Becomes

Further, the barrier layer 6 on the side wall and the bottom of the recess 2 is formed.
In order to change the activity of the surface of the barrier layer 6, the constituent material of the barrier layer 6 is a material composed of two or more elements.
By making the side wall and bottom of the recess 2 different, the recess 2
The growth of the Cu film from the bottom can be made faster than the side wall.

The barrier layer 6 on the side wall and the bottom of the recess 2 is formed.
In order to change the surface activity of the catalyst, a catalyst metal (for example, Au, Ag, Fe, Co, Ni, Ru, P
Irradiating the bottom of the recess 2 of the substrate 1 with the organometallic source gas (d, Pt, W, Os, Ti, Rh) can also make the growth of the Cu film from the bottom of the recess 2 faster than the side walls.

Further, in order to change the activity of the surface of the barrier layer 6 on the side wall and the bottom of the concave portion 2 of the substrate 1, a polymer protective film is formed on the entire surface of the concave portion 2 and the bottom of the concave portion 2 is subjected to RIE. By forming the film while holding the polymer film on the side wall by performing anisotropic etching, the growth of the Cu film from the bottom of the concave portion 2 can be made faster than that of the side wall.

FIG. 7 is a diagram showing a configuration example of a film forming / embedding apparatus using an FAB source for performing the substrate film forming method according to the present invention. The film forming / embedding apparatus 10 has a reaction chamber 11, and the inside of the reaction chamber 11 is evacuated by an exhaust system having a vacuum pump (not shown). The substrate 1 supported by the substrate support mechanism 12 is disposed at a lower portion in the reaction chamber 11, and a particle beam source 13, which is an FAB source, is directed toward the surface of the substrate 1.
, A parallel neutral particle beam 14 is irradiated. Further, the substrate support mechanism 12 is configured to rotate around a rotation shaft 15. The rotating shaft 15 penetrates the wall of the reaction chamber 11 via a magnetic fluid seal 19.

The particle beam generating source 13 which is a FAB source has a particle beam generating chamber 13-1 in the upper part of the reaction chamber 11, and a gas inlet 1 is provided in the particle beam generating chamber 13-1.
Gas distribution plate 1 for distributing first gas 17 introduced from 6
3-2, a first cathode 13-3, and an anode 13-4 are arranged, and a second cathode 13-5 is arranged at a lower end of the particle beam generation chamber 13-1. The inside of the reaction chamber 11 is evacuated to a predetermined low pressure by an exhaust system, a predetermined voltage value is applied from a DC power supply 18 to the anode 13-4, and a first gas 17 is further introduced from a gas inlet 16. As a result, the raw material gas distributed by the gas distribution plate 13-2 becomes the first cathode 1
Plasma is generated and ionized in a space between the anode 3-4 and the anode 13-4 and in a space between the anode 13-4 and the second cathode 13-5.

The ionized raw material gas particles are
Neutralized when passing through the small holes of the cathode 13-5.
When the particles are neutralized in this way, they are emitted from the particle beam source 13 as parallel neutral particle beams 14 without repulsion (without diverging) from each other. A reaction gas, for example, Cu (hfac), for causing a Cu-CVD reaction in the reaction chamber 11 is a second gas 2.
It can be supplied as 0.

The pressure in the reaction chamber 11 is increased by the second cathode 13-
By adjusting the distance between the substrate 5 and the substrate 1 to be within the mean free path of the particles of the neutral particle beam 14 in parallel,
The particles can reach the surface of the substrate 1 almost without collision. Then, it collides only with the bottom barrier layer formed on the inner surface of the concave portion formed on the surface of the substrate 1.

When reducing the bottom of the concave portion, the first portion supplied to the particle beam generation chamber 13-1 of the particle beam source 13 is used.
For example, hydrogen gas is used as the gas 17. Hydrogen is released through the small holes of the second cathode 13-5 in an excited state or a radical state having a high energy level, and thus has a high reducing ability. In addition, since the parallel neutral beam goes straight, hydrogen radicals collide only at the bottom of the concave portion, and only the bottom of the barrier layer in this portion is reduced. After only the barrier layer at the bottom of the concave portion is reduced, the second gas 20 which is a Cu-CVD reaction gas is supplied into the reaction chamber, thereby forming a film at a high film forming rate from the bottom surface of the concave portion. .

When removing the oxide film at the bottom of the concave portion, the energy of the neutral particle beam 14 is increased,
What is necessary is just to remove the bottom surface by sputtering. After the oxide film at the bottom of the recess is removed, a second gas 20 which is a Cu-CVD reaction gas is supplied into the reaction chamber 11, whereby a film is formed from the bottom of the recess at a high deposition rate. . In this case, an inert gas such as an Ar gas may be used as the first gas 17 to be supplied to the particle beam generation chamber 13-1, but a reducing gas such as a hydrogen gas is also used, and reduction and sputter removal are performed. The two effects may be aimed at simultaneously.

Further, a catalyst metal (eg, Au, Ag, Fe, Co, Ni, Ru, P
By irradiating the substrate 1 with the neutral particle beam 14 in which the organometallic raw material gas of d, Pt, W, Os, Ti, Rh) goes straight, the catalytic metal adheres to the bottom of the concave portion and is catalyzed. In this catalyzed state, by supplying a second gas 20 which is a Cu-CVD reaction gas into the reaction chamber,
Film formation with a high film formation rate is performed from the bottom of the concave portion.

[0045]

As described above, according to the invention described in each claim, the following excellent effects can be expected.

According to the first aspect of the present invention, the activity of at least the surface of the side wall and the bottom of the thin film in the concave portion of the substrate is changed, or the activation of the side wall and the bottom is performed during the film formation of the embedding material. By changing the degree, the deposition rate from the bottom surface is increased,
Film formation from the side wall surface can be eliminated or delayed, and film formation (embedding of the concave portion) without generation of seams or voids at the center of the concave portion can be performed.

According to the second and third aspects of the present invention, the difference in the degree of oxidation and / or the degree of reduction in at least the surface of the side wall and the bottom of the concave portion is provided, so that the next step of the CVD process can be performed. By making the growth rate of the Cu or Cu alloy film different, the film formation rate from the bottom surface of the concave portion can be increased, and the film formation speed from the side wall surface can be reduced. Film formation (recess filling) can be performed without generation.

According to the fourth aspect of the present invention, since only the bottom of the concave portion of the substrate is provided with atoms or molecules having at least one of a reducing action, a catalytic action, or a reaction promoting action or imparting an atom or a molecule for promoting the action. The activity becomes higher, the film forming speed from the bottom surface of the concave portion can be increased, and the film can be formed without generation of seams or voids in the central portion of the concave portion.

According to the fifth aspect of the present invention, the substance to be embedded in the concave portion is copper or a material containing copper as a main component, and the thin film is mainly a barrier layer for preventing diffusion of copper. Therefore, copper or a film containing copper as a main component can be formed without generation of a seam or void at the center of the concave portion.

[Brief description of the drawings]

FIGS. 1A to 1C are explanatory views of a process of forming a circuit wiring on a semiconductor substrate.

FIGS. 2A and 2B are views showing a state where a concave portion on a semiconductor substrate is buried by film formation.

FIG. 3 is a diagram showing a schematic configuration of an apparatus for performing a substrate film forming method according to the present invention.

FIG. 4 is a view for explaining reduction of a concave portion of a substrate by a substrate film forming method according to the present invention.

FIG. 5 is a view for explaining a step of embedding a concave portion of a substrate by a substrate film forming method according to the present invention.

FIG. 6 is a view for explaining a step of embedding a concave portion of a substrate by a substrate film forming method according to the present invention.

FIG. 7 is a diagram showing a configuration example of a film forming / embedding apparatus for performing the substrate film forming method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Concave part 3 FAB source 4 Neutral beam 5 Gas 6 Barrier layer 10 Deposition / embedding device 11 Reaction chamber 12 Substrate support mechanism 13 Particle beam generating source 14 Neutral particle beam 15 Rotation axis 16 Gas inlet 17 First Gas 18 DC power supply 19 Magnetic fluid seal 20 Second gas

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Araki 11-1 Haneda Asahimachi, Ota-ku, Tokyo F-term in Ebara Corporation (reference) 4M104 BB04 BB32 DD22 DD23 DD44 DD45 DD46 HH13 5F033 HH11 HH32 MM01 MM12 MM13 PP08 PP11 QQ48 QQ59 QQ62 QQ94 XX02

Claims (5)

[Claims] In a substrate film forming step in which a fine concave portion for a wiring pattern is formed on the surface, a thin film is formed on the inner surface of the concave portion, and then the concave portion is embedded and filled, a side wall portion and a bottom portion of the thin film are provided. Forming a film while changing the activity of at least the surface or the activity of the side wall and the bottom during the embedded film formation of the embedding material. 2. The method for forming a substrate according to claim 1, wherein the method of changing the degree of activity includes at least a difference in the degree of oxidation and / or a difference in the degree of reduction of the surface of at least the side wall and the bottom of the recess. A method for forming a film on a substrate, comprising: 3. The substrate film forming method according to claim 2, wherein the entire surface of the thin film is first oxidized or reduced in order to impart a difference in the degree of oxidation and / or a difference in the degree of reduction to the surface of the thin film. A method of forming a substrate, comprising reducing or oxidizing only a thin film at the bottom of a concave portion or removing an oxidized or reduced portion at the bottom. 4. The method according to claim 1, wherein the reducing action is performed only on the bottom of the concave portion to change the activity of the thin film or the surface of the thin film, or during the burying process of the burying material. A method of forming a film on a substrate, comprising adding atoms or molecules that have or promote at least one of a catalytic action and a reaction promoting action. 5. The substrate film forming method according to claim 1, wherein the material to be embedded in the concave portion is copper or copper as a main component, and the thin film is mainly formed. A method for forming a substrate, comprising a barrier layer for preventing diffusion of copper.