JPH06340969A - Target for sputtering and production thereof - Google Patents

Abstract

PURPOSE:To produce a target for sputtering capable of reducing the amt. of particles generated during sputtering. CONSTITUTION:This target consists essentially of titanium and nitrogen in 0.35-0.55 atomic ratio of N to Ti and has a TiN type phase as the principal phase. This target is produced by transforming the structure of a sintered compact consisting essentially of titanium and nitrogen in 0.35-0.55 atomic ratio of N to Ti by heating into a structure having a TiN type phase as the principal phase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering target containing less nitrogen than the stoichiometric composition for producing a film made of nitrogen and titanium by reactive sputtering or ordinary sputtering, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, with higher integration of LSIs, a P-type or N-type doped layer formed directly under a contact hole is formed in a shallower and narrower region.
When the above-mentioned LSI dope layer is shallow, if aluminum or the like used as wiring is directly formed on the silicon substrate, they cause an interdiffusion reaction and aluminum or the like easily breaks through the dope layer to destroy the semiconductor junction structure. The problem occurs.

In order to prevent such mutual diffusion reaction,
A diffusion preventing layer (also referred to as a barrier metal layer) made of a high melting point material such as a titanium-tungsten alloy layer or a titanium nitride compound layer is formed on an ohmic contact between a wiring and semiconductor silicon. Among the diffusion prevention layers, the titanium nitride compound layer is said to be particularly excellent in the diffusion prevention property, and studies are underway to make the titanium nitride compound layer the diffusion prevention layer.

As a method for forming the titanium nitride compound layer which becomes the diffusion prevention layer, there is a monthly semiconductor world 199.
2.12, p196-p205 or Monthly Semiconductor World 19
The following method is usually used as shown in 89.12, p189-p192. (1) After forming a titanium thin film on a silicon substrate by sputtering using a pure titanium target,
A thermal nitriding method of forming a titanium nitride compound layer by nitriding the surface layer of a titanium thin film by heat treatment in a nitrogen or ammonia gas atmosphere. (2) A reactive sputtering method in which a pure titanium target is used to react with nitrogen in a sputtering gas to form a titanium nitride thin film having a stoichiometric composition.

[0005]

DISCLOSURE OF THE INVENTION The present inventors changed the reactive sputtering method to a pure titanium target, and changed the target to a target in which titanium was in excess of the stoichiometric composition,
By using (hereinafter referred to as TiNx target), it was found that the composition of the formed thin film and the hysteresis property of the sputtering conditions can be reduced, and Japanese Patent Application No. 4-44653,
The application is made in Japanese Patent Application No. 4-172092.

Further, as described in JP-A-63-259075, an attempt has been made to obtain a film in which the ratio of nitrogen and titanium is changed by performing ordinary sputtering using a TiNx target. As described above, although the use of the TiNx target is expanding, in common with the reactive sputtering method and the normal sputtering method described above, further reduction of the particles generated during the sputtering period is a major problem to be solved. Has become.
The particles are foreign particles that adhere to the generated thin film, and for example, when the particles are generated in the diffusion prevention layer of the semiconductor, they cause a partial disconnection or a short circuit. An object of the present invention is to provide a sputtering target capable of reducing particles generated during the sputtering period and a method for manufacturing the same.

[0007]

Means for Solving the Problems The present inventors have made detailed studies on the generation of crystal phases and particles produced in a binary alloy of titanium and nitrogen, and have found that the atomic ratio of nitrogen to titanium (nitrogen / titanium) (hereinafter Atomic ratio X) is 0.35
The inventors have found that a target obtained by transforming a material having a content of 0.55 or less into a TiN-type phase, which is a stable phase on the high temperature side, can significantly reduce particles, and reached the present invention. That is, the present invention is a sputtering target characterized in that it is substantially composed of titanium and nitrogen, the atomic ratio X of nitrogen and titanium is 0.35 or more and 0.55 or less, and the TiN type phase is the main phase. is there.

In the sputtering target of the present invention, a sintered body having an atomic ratio X of nitrogen and titanium of 0.35 or more and 0.55 or less is heat-treated to form a structure having a TiN type phase as a main phase. It is preferably obtained by the production method of the invention. Further, in the manufacturing method of the present invention, if machining is applied in the state of a low hardness sintered body having a Ti ₂ N type phase as a main phase,
It is possible to significantly reduce the processing man-hour. In the present invention, the main phase means that the volume is 50% or more, preferably 80% by volume.
It means to occupy more than%.

[0009]

One of the greatest features of the present invention is that the atomic ratio X is 0.
The material in the range of 35 to 0.55 is stable at high temperature
That is, it was used as an N-type target. By using the TiN-type target that is stable in the high temperature range of the present invention, phase transformation does not occur on the target surface even by heating during the sputtering period, and the generation of particles due to the phase transformation can be reduced. In the present invention, the atomic ratio X is 0.35.
The reason above is that if it is less than 0.35, αTi becomes the main phase even in a high temperature range, and it is substantially impossible to make the TiN type phase the main phase as in the present invention.

On the other hand, if the atomic ratio X exceeds 0.55, the Vickers hardness during sintering exceeds 1600 and the workability becomes extremely poor, which is not preferable. In the region where the atomic ratio X of titanium and nitrogen is 0.35 or more and 0.55 or less, a Ti ₂ N type phase having low hardness and excellent workability may be set as a main phase depending on heating and cooling conditions in the manufacturing process. It is possible and primary processing is performed with the Ti ₂ N phase being the main phase, and stable Ti at high temperatures
If the secondary processing is performed after the transformation into the N-type phase, the target can be manufactured more efficiently. Further, as another method for producing the present invention, it can be obtained by keeping TiN in a high temperature region of 1000 ° C. or higher where it becomes a single phase at the time of sintering, and then forming a uniform structure of the TiN single phase and then quenching. However, this method has a drawback that an intermediate state with good workability cannot be obtained.

[0011]

EXAMPLES Nitrogen 2 having an atomic ratio X of nitrogen / titanium of 1
2.6 wt%, balance titanium, purity 99.99% or more, titanium nitride powder having an average particle size of 40 μm and pure titanium powder having a purity of 99.99% or more, average particle size of 40 μm were mixed in a specific mixing ratio, and V Mixed with a mold blender. The obtained mixed powder was filled in an Fe capsule for a hot isostatic press (hereinafter referred to as HIP) having an inner diameter of 400 mm, and then 1250 ° C. × 3
HIP under the condition of 120 MPa for 600 hours
After cooling at a cooling rate of 300 ° C./hour to room temperature by allowing to cool to room temperature, the Fe capsules are removed, and then the atomic ratio X of nitrogen / titanium of φ330 × 9 mmt is 0.2 to 0.3 mm. A sintered body of 0.7 shown in Table 1 was obtained.

[0012]

[Table 1]

Table 1 shows the nitrogen / titanium atomic ratio, the relative density, the volume fraction of the crystal phase, the Vickers hardness and the occurrence of chipping during machining of the sintered body obtained at this time. The chipping referred to here is a surface peeling with a depth of 0.1 mm or more mainly generated at the end of the ground surface, and tends to spread to the ground surface as the grinding progresses. The flattening processing conditions were as follows: grindstone rotation speed 1200 rpm, feed rate 12 m / min, depth of cut 10 μm, and grindstone material diamond No. 140. The crystal phase was determined by X-ray diffraction analysis. Among the obtained sintered bodies, sample No. in which peeling did not occur 1-Sample No. 6 in vacuum at 1400 ° C
It heated at x20 hr. After that, φ30 by machining
A target of 0 × 6.35 mmt was prepared. Table 2 shows the volume fraction and Vickers hardness of the crystal phase of the target obtained at that time.

[0014]

[Table 2]

By the heat treatment, the TiN type phase is converted to 80%.
It turns out that it becomes more than%. By this heat treatment,
The Vickers hardness value is increasing and Ti with good workability
It can be seen that it is better to perform the primary processing in the state where the ₂ N type is the main phase. According to X-ray diffraction analysis, a small amount of σ'type phase was detected, which is considered to be a fine precipitate phase generated during cooling. In addition, in the sample No. which was the αTi single phase of the comparative example.
No. 6 was confirmed by X-ray diffraction analysis even after heat treatment. Sample No. of the present invention example. 1-No.
The state of generation of particles of 0.5 μm or larger when sputtering was performed using the target of No. 5 was investigated. Further, as a target of the comparative example, a target having the same shape that was sintered under the same conditions and not subjected to heat treatment was manufactured, and the generation state of particles was investigated under the same conditions. The results are shown in Table 3. The sputtering conditions at this time are shown in Table 4.

[0016]

[Table 3]

[0017]

[Table 4]

According to Table 3, Ti by the heat treatment of the present invention
Targets with 80% or more N-type phase generate particles much less than Ti ₂ N-type targets, and the target in which TiN-type phase accounts for 80% or more suppresses particle generation. It was confirmed to be effective.

[0019]

According to the present invention, the TiN type phase is the main phase, and the target having a composition range of titanium and nitrogen which is excellent in workability is used, so that the target has less nitrogen than the stoichiometric composition. The generation of particles can be greatly reduced. Further, as shown in the manufacturing method of the present invention, the primary processing in a sintered state of low hardness and the transformation into the TiN type phase by the heat treatment is effective for a target mainly composed of the TiN phase having a problem in workability. This is a very effective manufacturing method.

Claims (3)

[Claims] 1. It is composed substantially of titanium and nitrogen, and the atomic ratio of nitrogen to titanium (nitrogen / titanium) is 0.35 or more and not less than 0.1.
A target for sputtering characterized by having a TiN type phase of 55 or less and a main phase being a main phase. 2. It is substantially composed of titanium and nitrogen, and the atomic ratio of nitrogen to titanium (nitrogen / titanium) is 0.35 or more and not more than 0.1.
A method for producing a sputtering target, which comprises subjecting a sintered body of 55 or less to a heat treatment to transform it into a structure in which a TiN-type phase is a main phase. 3. Substantially composed of titanium and nitrogen, and the atomic ratio of nitrogen and titanium (nitrogen / titanium) is 0.35 or more.
A sputtering target characterized by having a ratio of 55 or less and subjecting a sintered body having a Ti ₂ N-type phase as a main phase to mechanical processing and then subjecting it to heat treatment to transform it into a structure having a TiN-type phase as a main phase. Manufacturing method.