JPH1088334A - Target for magnetron sputtering - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a magnetron sputtering target made of titanium which is excellent in a bottom coverage effect. SOLUTION: A titanium material in which the crystal orientation is adjusted by rolling, heat treatment, or the like, and the strength ratio ((103) / (002)) between the (103) plane and the (002) plane of the titanium material is 4 or more. A target is configured using.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetron sputtering target. More particularly, the present invention relates to a step coverage of a thin film adhered to a substrate such as a wafer, and more particularly to a magnetron sputtering target made of titanium having improved bottom coverage.

[0002]

2. Description of the Related Art In recent years, a sputtering method as a physical thin film forming method has been used in many fields such as wiring materials for semiconductors and magnetic thin films for magnetic storage media. As one type, a titanium target is used to form Ti or TiN inside contact holes and through holes for the purpose of ensuring the reliability and electrical characteristics of a semiconductor device. For example, a thickness of 1000 between a conductive metal Al film and a semiconductor Si substrate.
A barrier layer TiN film of about Å is deposited by a sputtering method to prevent mutual diffusion between a metal Al film and a semiconductor Si substrate.

However, in the field of semiconductors, as device miniaturization and integration increase, the aspect ratio of contact holes and through holes increases, and sufficient step coverage cannot be obtained by conventional sputtering techniques. .

For the purpose of improving step coverage,
As for the sputtering apparatus, a collimated sputtering process and a remote sputtering process have been developed in order to allow only sputtered particles that are incident almost perpendicularly to the wafer to reach the wafer. It is known that the sputtering method differs from the vapor deposition method by evaporating the molten metal, and the crystal structure on the surface and inside of the target greatly affects the emission characteristics of atoms from the target. For example, according to a Wehner experiment using a single crystal of silver or copper, the emission density of atoms from a target is high in the (110) direction, which is the closest density direction of the crystal structure, and a spot-like shape is formed on a wafer. It is described that a distribution can be obtained [Physical Review (Phys. Rev.) 102, p. 699 to (1956)].

[0005]

The step coverage has been improved by the development of the collimated sputtering process and the remote sputtering process.
In particular, in order to further improve the bottom coverage improvement effect, it has been desired to develop a target having a large vertical component of the emitted atoms. An object of the present invention is to clarify the relationship between the crystal orientation of the titanium target surface and the bottom coverage, improve the coverage, and provide a magnetron sputtering target for forming a thin film excellent in ensuring the reliability and electrical characteristics of a semiconductor device. To provide.

In view of such circumstances, as a result of intensive studies on the influence of the crystal orientation of the titanium surface on the emission of atoms by sputtering, as a result, (1)
The intensity ratio of the (03) plane and the (002) plane by the X-ray diffraction method (1
When 03) / (002) was 4 or more, it was found that the bottom coverage was improved, and the present invention was completed.

[0007]

That is, the present invention relates to a magnetron sputtering target made of titanium, wherein the (103) face of the sputtering surface and the (00) face are formed.
2) A magnetron sputtering target having a plane intensity ratio [(103) / (002)] of 4 or more.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in more detail. As the titanium used as the target material in the present invention, high-purity titanium having a purity of 99.995% or more is used. Therefore, the target of the present invention has a quality in which the intensity ratio [(103) / (002)] between the (103) plane and the (002) plane of the surface to be subjected to sputtering is about 4 or more, preferably about 10 or more. It is characterized by.

The target material having such a crystal orientation is not unique depending on the material to be used, but if the material to be used as a raw material is specified, it can be easily determined by selecting plastic working conditions such as rolling and heat treatment conditions. By controlling the crystal orientation of the material surface, the intensity ratio can be adjusted.

More specifically, a high-purity titanium ingot is reduced to a rolling reduction of 70% to 90%, more preferably 80% to 90% by plastic working such as rolling. 1 hour, preferably from about 550 ° C. to about 600
It can be obtained by performing heat treatment at about 1 hour. The larger the amount of plastic working (reduction), the better, but if too large, the working time will be long and the productivity will be reduced. The heat treatment temperature is preferably as high as possible. However, if the heat treatment temperature is too high, abnormal growth of crystal grains is caused, and coarse crystal grains are formed.

Usually, the average grain size of the target material of the present invention is about 500 μm or less, preferably about 50 μm or less. By adopting the above processing conditions,
(103) /
A (002) plane having an intensity ratio of about 4 or more and an average crystal grain size of about 500 μm or less, satisfying the above range can be obtained.

[0012]

The present invention will now be described by way of examples, which should not be construed as limiting the invention. In the present invention, (1)
The intensity ratio of the 03) / (002) plane and the bottom coverage were measured by the following methods.

[0013] Intensity ratio of crystal orientation: The surface to be measured is cut by a lathe or the like, and an extremely thin deformed region in the surface layer by cutting is removed by etching treatment. The intensity of the corresponding diffraction line was measured, and the measured intensity of the obtained diffraction line was determined according to ASTM 5-0.
A corrected intensity value was obtained by performing a correction based on the relative intensity ratio of each crystal orientation described in 682, and the intensity ratio was calculated using this value.

Bottom coverage: The film thickness near the hole entrance and the film thickness at the center of the hole bottom were measured from an SEM photograph, and calculated by the following equation. [(Film thickness at bottom of hole) / (film thickness near entrance of hole)] × 100 (%)

Example 1 A high-purity titanium material having a purity of 99.995% was reduced to a rolling reduction of 80%.
After rolling at 590 ° C in air,
It was processed into a diameter of about 300 mm and a thickness of 6.35 mm to obtain a flat sputtering target. The crystal orientation intensity ratio of this target material was measured. Table 1 shows the results.

[0016]

[Table 1]

Next, using the target obtained in this manner, a hole having an aspect ratio of 2 is formed by sputtering using a collimator having an aspect ratio of 1, and the bottom coverage is measured from an SEM photograph of a cross section of the hole. did. As a result, bottom coverage is 24.0%
Met.

Example 2 A high-purity titanium material having a purity of 99.995% was reduced to a rolling reduction of 70%.
After rolling at 600 ° C. in the atmosphere,
It was processed into a diameter of about 300 mm and a thickness of 6.35 mm to obtain a flat sputtering target. The crystal orientation intensity ratio of this target material was measured. Table 2 shows the results.

[0019]

[Table 2]

Next, using the thus obtained target, a film was formed in a hole having an aspect ratio of 2 by a low-pressure remote sputtering method in which the distance between the target and the wafer was 270 mm, and bottom coverage was obtained from a SEM photograph of a cross section of the hole. Was measured. As a result, the bottom coverage is 51.
2%.

Comparative Example 1 A high-purity titanium material having a purity of 99.995% was reduced to a rolling reduction of 50%.
After rolling at 550 ° C in air,
It was processed into a diameter of about 300 mm and a thickness of 6.35 mm to obtain a flat sputtering target. The crystal orientation intensity ratio of this target material was measured. Table 3 shows the results.

[0022]

[Table 3]

Next, using the target thus obtained, a film is formed in the same manner as in Example 1,
Bottom coverage was measured from a SEM photograph of a cross section of the hole. As a result, the bottom coverage was 19.8%.

Comparative Example 2 A high-purity titanium material having a purity of 99.995% was reduced to a rolling reduction of 50%.
After rolling at 540 ° C in air,
It was processed into a diameter of about 300 mm and a thickness of 6.35 mm to obtain a flat sputtering target. The crystal orientation intensity ratio of this target material was measured. Table 4 shows the results.

[0025]

[Table 4]

Next, using the target thus obtained, a film is formed by the same method as in the second embodiment.
Bottom coverage was measured from a SEM photograph of a cross section of the hole. As a result, the bottom coverage was 44.5%.

[0027]

As described in detail above, in the present invention, as the magnetron sputtering target made of titanium, (103) and (00) on the surface of the target material are used.
The thin film obtained by sputtering using such a target only has a crystal orientation intensity ratio of 2) or more which is equal to or more than a specific value, and improves the bottom coverage on the wafer,
It enables the reliability and electrical characteristics of a semiconductor device to be ensured, and its industrial value is extremely large.

Claims (1)

[Claims] In a magnetron sputtering target made of titanium, the intensity ratio ((103) / (002)) between the (103) plane and the (002) plane is 4
The above is a target for magnetron sputtering.