JPS63312975A - Aluminum sputtering target - Google Patents

Abstract

PURPOSE:To form a thin sputtered film having highly uniform thickness by specifying the distribution of a crystal orientation inclusion ratio on the sputtering surface of a circular sputtering target consisting of Al or an Al alloy. CONSTITUTION:The circular target consisting of Al or an Al alloy is sputtered to form the thin film of Al or the Al alloy. In the sputtering surface of the target, the (220)/(200) crystal orientation inclusion ratio of (220) face to (200) face measured by X-ray diffraction is adjusted so that the ratio on the outer periphery is made larger than that at the center. In this case, the (220)/(200) at the center, preferably within <30% of the radius of the center, is adjusted to <1.0, and the (220)/(200) outside >=85% of the radius of the center is preferably adjusted to >=1.0. The adjustment can be performed, for example, by a combination of plastic working and heat treatment. By this method, an Al sputtering target capable of providing the sputtered film having uniform thickness is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an aluminum sputtering target. Specifically, the present invention relates to an aluminum sputtering target used when forming a thin film of aluminum or aluminum alloy by sputtering.

[Conventional technology]

In the sputtering method, ions are irradiated onto a target Ic.

This is a method of forming a thin film by colliding with a substance on the target surface to vaporize it and depositing the vaporized target substance on a substrate, and is widely used in the field of thin film formation. Sputtering equipment varies depending on the method of generating the ionized gas or discharge plasma that is the impact ion source, the type of applied power source, the structure of the electrode, etc.;
Divided into glow discharge type, bipolar RF glow discharge type, ion beam type, magnetron type, etc.

They are used differently depending on the purpose.

FIG. 3 schematically shows the configuration of a magnetron type sputtering device as an example of a sputtering device. The substrate (3) and target (3) on which a thin film is to be formed are housed in a vacuum chamber (3/).

The sputtering surface (3q) of the target is opposed to the thin film formation surface (rear) of the substrate. To perform sputtering with this apparatus, for example, first, exhaust air from the vacuum exhaust port (33) and then vacuum the inside of the chamber (10-1). After creating a high vacuum of about !torr, a sputtering gas (Ar, etc.) is introduced through the sputtering gas supply port (3 holes) to vacuum the inside of the chamber.
Keep the pressure as low as orr. Next, when a voltage is applied so that the substrate becomes an anode and the target becomes a cathode, electrons are emitted from the target surface, collide with the sputtering gas in the chamber, and generate ions (such as Ar+), which are accelerated by the electric field. and collides with the sputtering surface of the target.

This collision energy causes atoms on the sputtering surface to be ejected, which are deposited on the thin film formation surface of the substrate to form a thin film of the target material.

Aluminum sputtering is performed when aluminum or an aluminum alloy (hereinafter also simply referred to as "aluminum") is used as a target material. The main use of aluminum sputtering is wiring on process 0 and L8. In this case, a sialuminum thin film is first formed on the entire surface of the silicon wafer 1 by sputtering, and then the thin film is etched according to a circuit pattern to form thin circuit lines.

[Problem that the invention seeks to solve]

The thin film formed on the through-hole wafer is finely etched according to a circuit pattern. In this case, the required width of the circuit thin line is about 0.7 to 5 μm. The formed thin wire is required to have uniform thickness in order to ensure its properties. In general, variations in thickness! It is said to be less than ¥.

However, normally, the thickness of a thin film formed on a wafer by sputtering has a distribution in which the thickness is thicker at the center facing the center of the sputtered surface of the target and thinner at one peripheral area. Therefore, no holes are formed around the wafer. The defective rate of circuits such as L8 increases and the yield rate worsens.

For this reason, active studies have been made on sputtering equipment, sputtering conditions, targets, etc. with the aim of improving the uniformity of the film thickness, but sufficient improvements have not yet been made.

[Means for solving problems]

Under these circumstances, the present inventors have conducted extensive studies with the aim of improving the uniformity of film thickness by improving the target, and have found that the orientation of the crystals of the target material, that is, the crystal orientation, will affect the thickness of the sputtered thin film. It has a large effect on the uniformity of

The present invention was achieved by discovering that a target with excellent performance can be obtained by adjusting the distribution of crystal orientation of an aluminum sputtering target (K) to a specific relationship.

That is, the gist of the present invention is a circular sputtering target made of aluminum or an aluminum alloy, and the sputtering surface of which is measured by X-ray diffraction (
The crystal orientation content ratio of the cocoO) plane and the (XOO) plane is (22
0)/(200), (2
20)/(200) and (220)/(ko0) on the outer periphery.
0) is larger in the aluminum sputtering target characterized by t-.

The present invention will be explained in detail below.

Aluminum or an aluminum alloy is used as the material for the aluminum sputtering target of the present invention. Examples of alloying elements include Ag, QOlOr, Ou
, Fe, Go, Li1Mg.

Mn, Mo, Ni, 81, Ta%Ti, V, W, Zr
One or more of these are used, and targets made of materials of various purity and composition are available depending on the application.

The aluminum sputtering target of the present invention is a circular sputtering target, and is characterized in that the distribution of crystal orientation content measured by X-ray diffraction on its sputtering surface is adjusted to a specific relationship.

First, a method for measuring the crystal orientation content ratio will be explained. Chemically dissolves the surface of the sample to be measured to remove the effects of processing. Next, for the surface to be measured, the intensity of diffraction lines corresponding to each crystal orientation is measured using an X-ray diffractometer. For each intensity value of the diffraction line obtained, the relative intensity ratio of the diffraction line for each crystal orientation (
For example, the correction intensity value is calculated by performing correction based on ASTM Yatei-07g71)C. A specific example of this correction method is shown in Table 1 below. As the X-rays, alpha rays are used for Ou-.

Table-! Next, a crystal orientation content ratio is calculated as a ratio of the obtained corrected intensities. For example, if the crystal orientation content ratio between the (coO) plane and the (co00) plane is expressed as (220)/(co00), this is calculated by the following equation.

Therefore, in the present invention, (200)/(,200) measured on the sputtering surface as described above has a gradient in the radial direction of the circular target, and (200)/(200) at the center of the circular target It is characterized in that (CocoO)/(Co00) at the circular outer periphery is larger than /(200).

The slope form of the above (2-〇)/(-〇〇) is 4! It is not limited to , but if it is okay for (ko00)/(ko00) to increase gradually from the center of the circle to the outer periphery, then 1 It may increase in a stepwise manner through steps or more steps, or it may increase by a combination of a gradual increasing portion and a stepwise increasing portion.

In the present invention, (220)/(20
0) If the distribution of crystal orientation is adjusted so that (CocoO)/(-〇〇) at the circular outer periphery is larger, an effect of improving the uniformity of the sputtered thin film can be observed. Preferably, (2〇O)/(〇〇) at the center of the circle is less than 〇, preferably less than O,S, and (〇〇〇) / (-〇〇) at the outer periphery of the circle. /, the distribution of crystal orientation is adjusted so that it is 0 or more, more preferably 2.0 or more. More specifically, the distribution of crystal orientation is as follows: (CocoO)/(-〇 〇）が／、0
less than, preferably (7,j or less), and the distance from the center of the circle is on the radius tsqbpt, preferably (it
(% to 30%) or more at the outer periphery is adjusted so that (220)/(cooo) is 0 or more, preferably 2.0 or more. If there is a gap between the center part and the outer peripheral part.

In this range, (λO)/(ko00) increases gently and/or stepwise from the center to the outer periphery as described above5! IC is adjusted.

The crystal orientation content ratio of the aluminum material for producing the sputtering target rattle of the present invention can be adjusted, for example, by a combination of plastic working and heat treatment. More specifically, the crystal orientation content ratio can be adjusted by subjecting the aluminum material to plastic working such as rolling or forging, and then annealing at an appropriate temperature. The degree of adjustment of the crystal orientation content ratio obtained when aluminum material is subjected to wm processing and heat treatment depends on the purity or composition of the aluminum material, casting conditions, type and conditions of plastic working, type and conditions of heat treatment, etc. -I can't say it legally. However, once the aluminum material and casting conditions are specified, the conditions for obtaining the required crystal orientation content ratio can be found by testing several plastic workings with different processing rates and heat treatments with different conditions. That's easy.

Although the conditions for the above-mentioned plastic working are not particularly limited, good results can usually be obtained at a working rate in the range of 50 to 90%.

The conditions for the above heat treatment are also not particularly limited, but usually io
The desired results can be obtained by heating in the range of o to zooo°C/OS-300 minutes.

Figure D is a graph schematically showing an example of the relationship between the annealing temperature and the ratio of each crystal plane when an aluminum material after rolling is annealed at various temperatures. The above-mentioned passage 5
The relationship also depends on the aluminum material, casting conditions, etc.
Once these are specified, it is easy to create a more detailed relational diagram as shown in FIG. 9 for them, and therefore appropriate processing conditions can be easily found experimentally.

When manufacturing the sputtering target 7) of the present invention, for example, the sputtering target 7) has a gradient of (220)/(,200) on the sputtering surface.
After adjusting the value of
0) to a high value.

After adjusting the (cocoO)/(200) of the entire material to a high value, plastic working is performed only on the center, and then heat treatment is performed to adjust the (-20)/(200) of the center to a low value. Examples include methods.

Taking as an example the case where the former method is employed, the method for manufacturing a snow-cutter ring target according to the method of the present invention will be specifically explained.

First, the entire aluminum material is subjected to a treatment consisting of a combination of plastic working and heat treatment as described above to adjust the (λ20n(200)) of the entire material to a low value, e.g., below O,S.・Next, plastic working only the area that will become the outer periphery of the circular target of the final product of the material 0 As a method of plastic working only this outer periphery, for example, Examples include a method in which compression is performed using a concave pressing die, and a method in which a concave material with a protruding outer periphery is compressed using a flat pressing die or a roll.

1A to 1B schematically show an example of compressing a flat material using a concave suppression die; FIG. 1A is a front cross-sectional view showing the state during compression processing; FIG. 1B is a front view showing the material after compression processing. Figures 1A to 1B schematically show an example of compressing a concave material with a flat plate-like suppression mold, and Figure 1A is a front cross-sectional view showing the state during compression processing. Figure B is a front view showing the material after compression processing.

In this way, the material that has been plastically worked only on the outer periphery is annealed at an appropriate temperature, and the outer periphery (CocoO
)/(-〇〇) to a high value, for example /, 0 or more.

In this way, if the crystal orientation distribution of a material made of aluminum is adjusted.

From these, the target disc-shaped part ((phantom,
A sputtering target as a final product can be obtained by cutting out (/j) etc. in Figure λB. The present invention is not limited to the following examples without exceeding the gist thereof.

Example 1 and Comparative Example 1 A disc-shaped material cut out from a billet of aluminum alloy (Si/%, balance A1 and impurities) was rolled (rolling rate: go) and annealed to make the entire material as shown in Table -λ. Sample A having the crystal orientation distribution shown below was obtained. [Here, the crystal orientation distribution (copper is the crystal orientation plane for each sample (///), (kooo)
, (CocoO) and (J//) correction strength (see Table 7)
The total is calculated as 1oo4. 〕table
- A circular sputtering target (target 1) with a diameter of /001RII and a thickness of IOIIIm was cut out from sample A.

On the other hand, a disk-shaped material (!;Omx
lx / 00wt) is cut out, and the entire material is rolled (rolling rate gO) and annealed to adjust the (kokoO)/(-〇〇) of the entire material to a low value of approximately O8-. 1. Next, using a pressing mold of the type shown in Fig. 1A, the outer periphery of the area having a distance of 30 degrees or more from the center is compressed at a reduction rate of 0.
Sample C with 2-〇)/(-〇〇) adjusted to a high value of about 3
I got it.

Diameter 1001n from the center of sample C, thickness 10mm
A circular sputtering target (Target II) was cut out. Center of target H (distance from center:
Table 3 shows the results of measuring the crystal orientation distribution for the outer circumferential portion (distance from the center: qo).

Table 3 Targets 1 and H were each attached to a magnetron type sputtering device, and Ar pressure was applied to
sCathode current 0. ! A and sputtering time! Aluminum sputtering was performed on a silicon Cueva substrate under the same sputtering conditions. The results are shown in Table 4.

In addition, the film thickness distribution ratio (忤) in the table is calculated using the formula: According to Table 2, it is clear that the target layer (1) in which the crystal orientation distribution has a gradient provides a sputtered film with higher uniformity.

〔Effect of the invention〕

According to the present invention, an aluminum sputtering target that provides a sputtered thin film with high uniformity of film thickness is provided. Therefore, the sputtering target of the present invention is suitable for the sputtering target. Wiring on L8 can be done more economically.

[Brief explanation of drawings]

Figures 7A-B schematically show an example of a method for plastic working the outer peripheral part of an aluminum material, Figure 1A is a front sectional view showing the state during compression processing, and Figure 1BFi material after compression processing. FIG. /: Upper press type, lower press type. 3: Material, material after mite processing, j: Cutting of product m. λ6h-B schematically shows another example of the method of plastic working the outer peripheral part of the material, FIG. FIG. /l: Upper pressing type, l lower pressing type, /3: Material, 14t: Material after processing. /Yo: The cut out armpit of the product. FIG. 3 is a diagram schematically showing the configuration of a magnetron type sputtering apparatus. J/:, 4 empty chambers, 3λ varnish supply port. 33: Vacuum exhaust port, J-mite board. 35: Target, 36: Magnet. 37: Cooling water inlet, 3g: Cooling water outlet, 39 Varnish batter surface, R: Thin film forming surface. Figure D is a diagram schematically showing an example of the relationship between annealing temperature and the ratio of each crystal plane. Patent applicant Naoetsu Kasei Co., Ltd. Agent Patent attorney For quality − Others/names

Claims (3)

[Claims] (1) A circular sputtering target made of aluminum or aluminum alloy, whose sputtering surface has a (220) plane and a (220) plane measured by X-ray diffraction method.
The crystal orientation content ratio with the 00) plane is (220)/(200)
When, (220)/(200) of the center of the above circular
) An aluminum sputtering target characterized in that (220)/(200) at the outer periphery is larger than (220)/(200). (2) In the aluminum sputtering target according to claim 1, the (22
0)/(200) is less than 1.0, and (22
0)/(200) is 1.0 or more. (3) In the aluminum sputtering target according to claim 2, (220)/(
200) is less than 1.0, and (220)/(2
00) is 1.0 or more.