JPS60194069A - Sputter target and sputtering method - Google Patents

Abstract

PURPOSE:To control easily the alloy ratio of the film to be formed on the surface of a material by disposing radially plural pieces of target materials consisting of different materials and making the areas occupied by the respective sputter materials correspondent with the sputter scattering speed or film forming alloy ratio. CONSTITUTION:Target materials 11 consisting of Si, etc. and target materials 12 consisting of Mo, etc. are alternately and radially arranged. The area ratio occupied by such materials 11, 12 is determined according to the sputter scattering speed of the respective sputter materials Si and Mo or the ratio of the alloy to be formed into the film. If sputtering is executed by using a sputter target combined with such target materials 11, 12, the film having a desired alloy ratio is formed and the waste of the sputter materials is prevented.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a technique for forming a thin film on the surface of a sample, and in particular, it involves colliding ions generated between an anode and a cathode with a sputtering target, and reducing the impact of the collision. This technology is effective in forming a film on the surface of a sample by scattering constituent atoms and molecules of a sputtering target emitted by energy.

[Background technology]

Conventionally, in order to form a film of electrode wiring material on the surface of a wafer used to form semiconductor devices, for example, argon ions, which are excited and generated by plasma discharge between an anode and a cathode, are bombarded with the surface of a sputter target. , the so-called sputtering method is used to form a film by scattering the atoms that make up the target (Kogyo Kenkyukai 1982).
(Refer to the 2017 electronic materials supplement). This method has been used to form thin films of high melting point metals such as At alloys and Mo (molybdenum) and W (tungsten).

However, since A4 alloy has a low melting point, it cannot be used in high-temperature processes, and Mo, W, etc. are easily oxidized.
Furthermore, because of poor workability, there has been a recent trend toward using an alloy (silicide) of a high-melting point metal and silicon as a gate electrode. Therefore, the following two methods can be considered for forming a silicide film on the upper surface of a wafer using the sputtering method described above.

(1) Like the metals necessary to form a silicide film,
A method of configuring sputter targets, placing each target on a sputter electrode, and sputtering at the same time.

(2) A method of mixing multiple metal powders at a fixed ratio, sintering with a catalyst, and sputtering using the powder as a target.

However, in the former method, since the sputter scattering speed of each metal is different, it is necessary to precisely control the voltage applied to the sputter electrode and the film formation time in order to obtain a constant alloy ratio. Technical and workability is extremely difficult.

In the latter method, since it is necessary to use a catalyst to sinter multiple metal powders, the catalyst itself is included in the alloy, and when sputtered, the catalyst is also sputtered and the atoms that make up the catalyst are will fly onto the surface and reduce the purity of the thin film. Therefore, a sputter target as shown in FIG. 1 can be considered. This sputter target 1 is composed of three target materials 2, 3.4, and the target material 2, for example, is arranged in an annular shape at the outermost position with old material. The target material 3 is made of 8i, which is the same material as the target material 2, and has a disk shape. The target material 4 is a single material different from the target materials 2 and 3, for example M.

It is arranged in an annular shape between member 2 and member 3.

To manufacture such a sputter target in which different materials are arranged concentrically, in the case of target 2, first prepare a disk (8i flat plate) made of a single Si material, and then set the MO of the disk. The portion to be disposed (the portion constituting the target material 4) is cut concentrically. Furthermore, a flat plate made of a single MO material (Mo flat plate) is prepared, and a portion where the target material 3 made of a single 8i material is to be placed is cut. Then, the sputter target 1 is manufactured by incorporating the processed MO flat plate into the nine-Si flat plate that has been cut and processed. However, the inventors have discovered that in order to manufacture such a target, it is necessary to cut a plurality of expensive single materials at various times, resulting in a large amount of waste.

[Purpose of the invention]

An object of the present invention is to provide a sputtering technique that facilitates control of the alloy composition ratio of a film formed on a sample surface.

Another object of the present invention is to provide a sputter target with a construction that does not result in wasted material.

The above and other objects and novel features of the present invention include:
It will become clear from the description of this specification and the accompanying drawings.

[Summary of the Invention] A brief overview of typical inventions disclosed in this application is as follows.

That is, by changing the area ratio occupied by the target material according to the sputtering speed of the material constituting the target material, and by arranging the target material radially, the alloy composition ratio of the material formed on the sample surface can be adjusted. can be easily controlled.

〔Example〕

FIG. 3 is a plan view of a sputter target according to an embodiment of the present invention, and FIG. 4 is a sectional view taken along the line ■--■ in FIG. In Fig. 3, sputter target number 0 has two types of target materials 11 and 12 arranged alternately.For example, target material 11 is made of a single material of 8i, target material 12 is
Suppose that it is made of a single material of MO. Hereinafter, the target material 11 is 8i material 11, and the target material 12 is MO
When the material 12 is assumed, the area ratio θI :02 occupied by the Si material 11 and the MO material 12 is determined as follows. For example, the alloy ratio of Si and MO in a film formed on a sample such as a wafer is 5:
If we consider the case where we want to form a film in step 3, the sputter scattering speed (i formation speed) of 8i and MO is
When a voltage of 600V is applied using (argon ion), for example, the ratio is 5:9 (HANDBOOK O
F THIN FILMTBCHNOLOGY, 197
(see 0).

Therefore, since the alloy ratio is proportional to the product of the sputter scattering speed and the area ratio, if θI20 = 3:1, the alloy ratio of Si and Mo in the film formed on the wafer surface will be 5:3. Can be set. In this example, Si material (θ,
= 67.5°) and Mo material (θ, = 22.5°)
Four pieces of each are alternately combined to form a target occupied area of 8i and Mo at a ratio of 3:1. Note that θ8. θ! It is better to make it as small as possible to eliminate uneven film formation.

Next, an example of the method for manufacturing a sputter target according to this embodiment (in the case of forming a film having an alloy ratio of 84 and MO of 5:3 on the surface of a sample) will be described.

First, a disk made of a single material of Si and MO with a radius hole is prepared, and for the disk made of Si, θ+=67.
5°, and for a disk made of Mo, θ, = 22.
Cut at 5°. These target materials are alternately combined to form a disc-shaped sputter target (10). The target material is fixed using a metal 14 such as indium placed on a backing plate 13, as shown in FIG.
71, and mechanically fix it using screws 9, etc., as shown in the fifth column. Note that the remaining Si material and Mo material can be used when forming other sputter targets, so that almost no material is wasted when manufacturing the sputter target, and it can be used effectively.

FIG. 6 shows a sputtering apparatus which is an embodiment of the present invention.

The vacuum chamber 15 is connected to an exhaust pipe 1 by a vacuum pump (not shown).
6, and in that state, a small amount of gas (for example, Ar gas) is injected from the gas introduction pipe 17 to maintain the pressure at about 10"" Torr. A magnetic force is generated by the electromagnet 19 or a permanent magnet, and a magnetic flux is generated on the sputter target 10. In this state, when a voltage is applied between the electrode 18, that is, the target lO, and the anode 21, a plasma ring 22 is generated inside the magnetic flux. The plasma in the plasma ring 22 is in a state where gas is ionized, and positive ions, in this example Ar, are electrically attracted to the sputtering target 10, and the collision energy causes them to be ionized from the sputtering target 10. The atoms constituting the sputter target 10 scatter and form a film on the sample wafer 23. By the way, since this sputter target 10 is made up of multiple types of target materials divided and arranged radially, a fixing member such as a fixing ring is used. 24 is disposed around the sputter target (sputter target) 10. This fixing member 24 is slid toward the center or in the opposite direction by a driver (not shown) connected to the arm 25. When the size of the sputter target plate 10 is reached, the sputter target plate 10 is stopped and the upper surface of the sputter target plate 10 is suppressed. The lower surface is fixed, and the fixing ring 24
The upper surface of the target is fixed, and the target material constituting the target does not shift. Therefore, the present invention can be applied even when the sputter target is placed on the top of the sputter device.

Next, when the present invention is applied to a magnetron sputtering apparatus, the structure of a sputter target depending on the difference in plasma shape will be explained using FIGS. 8 to 10FgJ. In addition,
The sputter targets are 2gi type target materials A and B.
Suppose that it is composed of.

FIG. 8 shows a sputter target 27 in the case where the plasma ring 26 is generated in a circular shape, and C, target insertion, and B are arranged in a direction perpendicular to the normal line of the arc of the plasma ring 26.

FIG. 9 shows a sputtering target 29 in which the plasma ring 28 is generated in an oval shape, and the target materials A and B are placed in a direction perpendicular to the normal line of the circular arc portion of the plasma ring 28. The straight line portions are arranged perpendicularly to the straight line portions.

FIG. 10 shows a case where a sputter target 31 is placed inside the plasma ring 30, and target materials A and B are placed in a direction perpendicular to the normal line of the plasma ring 300.

〔effect〕

(1) A sputter target can be easily created by preparing a plurality of flat plates made of different sputtering materials, dividing each of the flat plates, and configuring a single sputter target by combining some of the divided target materials radially. Moreover, since the target material remaining after manufacturing the sputter target can be used when manufacturing other sputter targets, it is possible to prevent waste of expensive sputter materials.

(2) Divide a flat plate made of different sputtering materials to form target materials, assemble some of the target materials radially, and calculate the area ratio occupied by each of the different sputtering materials as the sputtering rate or the alloy to be formed. By setting the ratio according to the ratio, a film can be formed on the sample surface with a desired alloy ratio.

(3) Depending on the shape of the Prada 1 ring generated by magnetron sputtering, the size of the plasma ring can be varied by setting the direction in which target materials formed by dividing multiple plates of different sputtering materials are combined. However, by making sure that the area ratio occupied by each target material is just one, the holes formed on the sample surface can be formed with a stable alloy ratio.

As above, nine inventions made by the present inventor have been specifically explained based on examples, but it should be noted that the present invention is not limited to the above-mentioned examples and can be modified in various ways without departing from the gist thereof. Not even. For example, although this embodiment has been described using a magnetron sputtering device, it can also be applied to other sputtering devices such as a conventional diode sputtering device. Further, the sputter target may be fixed only by metal bonding or mechanically.

Further, in this example, the MO and Si target materials are arranged alternately, but they may be arranged irregularly.

[Application field]

In the above explanation, the invention made by the present inventor was mainly applied to the sputtering technique for forming semiconductor devices, which is the background field of application, but the invention is not limited to this, and for example, It can be used to form thin films on magnetic tapes and other articles.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a possible sputter target, FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1, and FIG. 3 is a plan view of a sputter target that is an embodiment of the present invention. The figure is an explanatory diagram of the case where the sputter target is fixed by metal bonding, and Figure 5 is an explanatory diagram of the case where the sputter target is mechanically bonded.
6 is a cross-sectional view taken along the -v line, FIG. 6 is a sputtering apparatus which is an embodiment of the present invention, FIG. 7 is a schematic diagram of a fixing member of a sputter target, and FIG. 8 is a diagram showing a case where a circular plasma ring is generated. Figure 9 is a diagram for explaining an applicable sputter target. Figure 9 is a diagram for explaining a sputter target applicable when an elliptical plasma ring is generated. Figure 1O is a diagram for explaining a cylindrical sputter target. This is a diagram to help you. 1.10.27, 29.31... Sputter target, 2, 3.11... Target material made of 81 material, 4
．． 12... Target material made of MO material, 9... Screw, 13... Backing plate, 14... Metal (metal bonding), 15... Vacuum chamber, 16...
- Exhaust pipe, 17... Gas introduction pipe, 1B... Sputter electrode, 19... Electromagnet, 21... Anode, 22.
26, 2, 8° 30... plasma ring, 23...
Wafer, 24... Fixing member, 25... Arm. Figure 1 Figure 2 Figure 3 Figure 1 Figure 4/j Figure 5 Figure 6 Figure 7 Figure 8 Figure A Figure 9 Figure 10

Claims (1)

[Claims] 1. A sputter target in which a plurality of target materials made of different sputter materials are arranged radially, and the ratio of the area occupied by each of the sputter materials is determined by the sputter scattering rate or film formation rate of each sputter material. A sputter target characterized by being compatible with an alloy ratio. 2. A sputter target configured in a circular manner by radially arranging a plurality of target materials made of different sputter materials, each target material corresponding to a region where plasma is generated being perpendicular to the normal direction of the region. The sputter target according to claim 1, wherein the sputter target is arranged in a direction in which the ratio of the area occupied by each of the sputter materials is determined according to the sputter scattering speed of each sputter material or the alloy ratio to be formed into a film. . 3. A sputter target configured in a cylindrical shape by radially arranging a plurality of target materials made of different sputter materials, each target material corresponding to a region where plasma is generated being perpendicular to the normal line of the region. The sputter target according to claim 1, wherein the sputter target is arranged in a direction in which the ratio of the area occupied by each sputter material corresponds to the sputter scattering speed of each sputter material or the alloy ratio to be formed into a film. . 4. A plurality of target materials made of different sputtering materials are arranged radially, and the ratio of the area occupied by each of the sputtering materials is adjusted according to the sputter scattering speed of each sputtering material or the alloy ratio to be formed into a film. A sputtering method in which a thin film is formed on the surface of a sample.