JP2000123634A - Copper very fine particle independent dispersion solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the viscosity of a dispersion solution in a specified value or less, and completely embed fine wiring grooves, via holes, and contact holes on an LSI board by mixing in a specified ratio Cu metal-containing very fine particles having a particle size of specified value or less and an organic solvent difficult to vaporize at room temperature, and vaporizing in a drying/baking process forming a Cu wiring circuit on a semiconductor board. SOLUTION: A Cu very fine particle independent dispersion solution is prepared by mixing an organic solvent and Cu metal-containing very fine particles having a particle size of 0.01 μm or less. The concentration of the Cu metal- containing very fine particles is 5-70 wt.%, preferably 15-20 wt.%. The organic solvent is a solvent capable of vaporizing at 150 deg.C or higher, and the Cu metal- containing very fine particles are very fine particles made of Cu, CuO, or a mixture of Cu and CuO. Very fine particle independent dispersion solution having a viscosity of 50 cP, preferably 10 cP or less is obtained. A conductive, uniform, very fine pattern is formed on the LSI board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Cu ultrafine particle independent dispersion used for forming fine wiring on a semiconductor substrate such as an LSI substrate and burying via holes and contact holes.

[0002]

2. Description of the Related Art Conventionally, when forming a multilayer wiring such as an LSI substrate, an organic solvent containing an alcohol or an organic ester having 5 or more carbon atoms has been used as a metal paste for forming a fine pattern with uniform conductivity. Particle size 1000Å
It is known that ultrafine metal particles (0.1 μm) or less are uniformly dispersed individually with their surfaces covered with the organic solvent (for example, Japanese Patent No. 25661537).

[0003]

However, such a conventional metal paste has the following problems. That is, the wiring width of the LSI substrate is 0.25 μm.
With the progress of miniaturization of m and 0.18 μm, drying starts before the applied metal paste sufficiently fills the inside of the wiring groove, and because the viscosity is high, the inside of the fine groove is completely filled. It was difficult.

The present invention has been made to solve the problems of the prior art, and can completely bury fine wiring grooves, via holes, contact holes, and the like in an LSI substrate, and can achieve uniform conductivity. It is an object of the present invention to provide a Cu ultrafine particle independent dispersion liquid capable of forming a fine pattern.

[0005]

The Cu ultrafine particle independent dispersion of the present invention has a viscosity of 50 cP or less, is difficult to evaporate at room temperature, and is used for drying and forming a Cu wiring on a semiconductor substrate.
Organic solvent that evaporates in the baking process, particle size 0.01μ
m or less and mixed with Cu metal-containing ultrafine particles,
The surface of the ultrafine particles is covered with the organic solvent and dispersed individually. The organic solvent preferably evaporates at 150 ° C. or higher. The organic solvent is preferably mineral spirit, tridecane, dodecylbenzene or a mixture thereof, or a mixture thereof with α-terpineol.
Hydrocarbons having 5 or more carbon atoms (e.g., pinene), alcohols (e.g., n-heptanol), ethers (e.g., ethylbenzyl ether), esters (e.g.,
n-butyl stearate, a ketone (eg, diisobutyl ketone, etc.), an organic nitrogen compound (eg, triisopropanolamine, etc.), an organic silicon compound (silicone oil, etc.), an organic sulfur compound, or a mixture thereof using Cu The mixture can be appropriately mixed depending on the use of the dispersion. The Cu metal-containing ultrafine particles are Cu, Cu
It is desirable to use ultrafine particles composed of O or a mixture of Cu and CuO. The concentration of the Cu metal-containing ultrafine particles is 5 to 70 wt%, preferably 15 to 50 wt%.
It is. If the concentration of the particles exceeds 70 wt%, the viscosity becomes too high, and if the concentration of the particles is less than 5 wt%, the film thickness becomes too small. The viscosity of the Cu ultrafine particle independent dispersion at 20 ° C. is 50 cP or less, preferably 10 cP or less. The Cu metal-containing ultrafine particles are C
In addition to the u metal element, it may contain at least one kind of metal having low solubility in Cu and easily reacting with the base material of the semiconductor substrate or a compound containing these metals, thereby improving the adhesion to the base material. I do. Specific examples of the metal other than the Cu metal element include, for example, Mg, Al, B, T
a, a metal selected from Nb and V, or a compound containing these metals. Compounds containing these metals include:
For example, (C ₁₇ H ₃₅ COO) ₂ Mg and the like can be mentioned. The amount of these metals or metal-containing compounds added to the Cu metal-containing ultrafine particles is 0.5 to 5 wt% based on the total weight of the ultrafine particles.
It is.

[0006]

EXAMPLES Examples of the Cu ultrafine particle independent dispersion of the present invention will be described below together with examples of use of the dispersion. (Example 1) C under the condition of helium pressure 0.5 Torr
When evaporating u and generating ultrafine particles of Cu by an in-gas evaporation method, the vapor of the mineral spirit is brought into contact with the ultrafine particles of Cu in the process of production, cooled and recovered, and dispersed independently in a solvent. A Cu ultrafine particle independent dispersion liquid containing 20 wt% of Cu ultrafine particles having an average particle diameter of 0.008 μm was prepared. This dispersion had a viscosity of 5 cP at room temperature.

Next, the via holes provided on the Si substrate were treated using the above-mentioned independent dispersion liquid of Cu ultrafine particles.
SiO ₂ as an insulating film formed on the Si substrate
The membrane has a pore size of 0.15 μm (aspect ratio 5), 0.25
A via hole of μm (aspect ratio 4) is opened, and a WN barrier film is formed with a thickness of 0.02 μm on the surface of the substrate including the inner surface of the via hole by sputtering. To C
u seed film is formed.

The above substrate is set on a spin coater and
Rotation at 00 rpm, the above Cu at room temperature from above
Spin coating was performed by dropping the ultrafine particle independent dispersion. This dispersion was filled in the via hole, and a flat liquid film of the dispersion was formed on the surface of the substrate. The substrate in this state is placed in a vacuum of 10 ⁻² Torr or less for 250
At ° C. of temperature, the organic solvent is evaporated by heating for 2 minutes, then the temperature was raised to 300 ° C., CO ₂ gas 760Torr
It was baked for 60 minutes in an atmosphere. Further, when the temperature is 400
C. and baked in an inert gas for 30 minutes. Thus, the Cu ultrafine particles are fused to each other, and C
A Cu thin film without any shrinkage or cracks embedded without voids was formed with u. Next, when the Cu film other than the inside of the via hole was subjected to CMP treatment, excess Cu on the substrate surface was removed, and a Cu thin film having a flat surface was formed in the via hole. Its specific resistance was 2.0 μΩcm. (Example 2) 0.01 T in helium gas of 1 Torr
In a mixed atmosphere of O ₂ gas of orr, Cu is evaporated to produce ultrafine particles of CuO, which are contacted with a mixed vapor of dodecylbenzene and diethyl phthalate and cooled to obtain an ultrafine CuO having an average particle size of 0.01 μm. A CuO ultrafine particle independent dispersion having a viscosity of 10 cP (20 ° C.) containing 25 wt% of fine particles was prepared. Further, this CuO ultrafine particle independent dispersion and the Cu ultrafine particle independent dispersion prepared in Example 1 were mixed,
A mixed dispersion of Cu and CuO having a viscosity of 7 cP (20 ° C.) was prepared.

Next, using the above-mentioned dispersion liquid, a via hole was buried in the substrate at room temperature in the same manner as in Example 1 to form a Cu film. As a result, any of the obtained thin films showed shrinkage and cracking even after sintering. No specific resistance and its specific resistance is 2.0μ
Ωcm. (Example 3) Instead of the Cu ultrafine particle independent dispersion in Example 1, Mg, Al, B, and Cu ultrafine particle independent dispersions in which 50 wt% of Cu ultrafine particles were dispersed in a mixed solvent of tridecane and phenetole were used. One to which an organic compound of Ta, Nb or V was added was produced in the same manner as in Example 1. The viscosity of this dispersion was 10 cP at 20 ° C.

Next, a step of forming a WN barrier film and a Cu seed film using these dispersions is omitted, and the other steps are the same as those in the first embodiment, and the via holes of the substrate are buried.
When the film was formed, the obtained thin film was still sintered and C
No shrinkage or cracking occurred during the planarization treatment step by MP, and the adhesion to the substrate was good, and the specific resistance was 2.1 μΩcm. (Example 4) Viscosity of 50 cP dispersed in a solvent obtained by mixing α-terpineol with the mineral spirit of Example 1
A (20 ° C.) Cu ultrafine particle independent dispersion was prepared, and using this, a wiring pattern was formed on a Si substrate. This S
A groove having a width of 0.25 μm and a depth of 1 μm (aspect ratio 4) is formed in a pattern on the SiO ₂ film as an insulating film formed on the i-substrate, and is formed on the surface of the substrate including the inner surface of the groove. Indicates that the WN barrier film has a thickness of 0.02 by sputtering.
.mu.m, and a Cu seed film is formed on the surface of the barrier film by sputtering.

The above substrate is set on a spin coater and 5
Rotation was performed at 00 rpm, and the above-described Cu ultrafine particle independent dispersion was dropped from above to perform spin coating. The dispersion liquid was filled in the pattern-shaped grooves, and a flat liquid film of the dispersion liquid was formed on the surface of the substrate. The substrate in this state is placed in a vacuum of 10 ⁻² Torr or less for 250
C. for 2 minutes to evaporate the organic solvent, then raise the temperature to 300.degree.
Firing was performed for 60 minutes in the presence of ₂ O gas (H ₂ O partial pressure: 10 Torr). Further, the temperature was increased to 400 ° C., and calcination was performed for 30 minutes in an inert gas from which H ₂ O had been removed. Thus, C
The u ultra-fine particles were fused to each other to form a Cu thin film without any shrinkage or cracking in which the inside of the groove was filled with Cu without any voids. Next, when the Cu film other than the inside of the groove was subjected to CMP treatment, excess Cu on the substrate surface was removed, and a Cu thin film having a flat surface was formed in the groove. Its specific resistance is 2.0
μΩcm.

[0012]

According to the Cu ultrafine particle independent dispersion of the present invention, fine wiring grooves, via holes, contact holes and the like of an LSI substrate can be completely buried, and a fine pattern with uniform conductivity can be formed. be able to.

Continuing from the front page (72) Inventor Hiroyuki Yamakawa 5-9-7 Tokodai, Tsukuba, Ibaraki Pref. Japan Vacuum Engineering Co., Ltd. (72) Inventor Hirohiko Murakami 5-9- Tokodai, Tsukuba, Ibaraki 7. Inside of Tsukuba Super Materials Research Laboratory

Claims (7)

[Claims] 1. The method according to claim 1, wherein the compound is hardly evaporated at room temperature and has C on the semiconductor substrate.
It is formed by mixing an organic solvent that evaporates in a drying / firing step when forming a u wiring and Cu metal-containing ultrafine particles having a particle size of 0.01 μm or less, and the surface of the ultrafine particles is formed with the organic solvent. It is covered and dispersed independently and has a viscosity of 5
A Cu ultrafine particle independent dispersion having a pressure of 0 cP or less. 2. The Cu ultrafine particle independent dispersion according to claim 1, wherein the organic solvent evaporates at 150 ° C. or higher. 3. The method according to claim 1, wherein the organic solvent is mineral spirit, tridecane, dodecylbenzene, or a mixture thereof.
Or α-terpineol or a hydrocarbon having 5 or more carbon atoms, alcohol, ether, ester, ketone, organic nitrogen compound, organic silicon compound, organic sulfur compound,
3. The Cu ultrafine particle independent dispersion according to claim 1, wherein the Cu ultrafine particle independent dispersion is a mixture of a mixture thereof. 4. The method according to claim 1, wherein the Cu metal-containing ultrafine particles are Cu, C
The Cu ultrafine particle independent dispersion according to any one of claims 1 to 3, wherein the ultrafine particles comprise uO or a mixture of Cu and CuO. 5. The concentration of the Cu metal-containing ultrafine particles is 5 to 5.
The Cu ultrafine particle independent dispersion according to any one of claims 1 to 4, wherein the content is 70 wt%. 6. The method according to claim 1, wherein the Cu metal-containing ultrafine particles contain, in addition to the Cu metal element, a metal having low solubility in Cu and easily reacting with a base material of a semiconductor substrate or a compound containing these metals. The Cu ultrafine particle independent dispersion according to any one of claims 1 to 5, wherein: 7. The Cu metal-containing ultrafine particles contain at least one metal selected from Mg, Al, B, Ta, Nb and V, or at least one compound containing these metals, in addition to the Cu metal element. The Cu ultrafine particle independent dispersion according to any one of claims 1 to 6, characterized in that: