JPS58100679A - Split target for sputtering - Google Patents

Abstract

PURPOSE:To facilitate manufacture and assembly of targets and to improve the quality of vapor deposited films by disposing the small segmental pieces of dissimilar kinds of target materials alternately, and setting the central angles of the small segmental pieces at the angles meeting those of the alloys to be vapor deposited. CONSTITUTION:Small segmental pieces 11 of dissimilar sputtering materials disposed alternately are mechanically fastened to a backing plate 15 by using retainers 13, 14. Thereafter, the central angles of the pieces 11, 12 are set at the angles meeting those of the alloys or intermetallic compds. to be vapor deposited to determine the compsn. ratios of films. The fayed surfaces in the transverse direction of the pieces 11, 12 are made inclined or stepped. The above-mentioned split targets are easy to manufacture and assemble and the quality of the vapor- deposited films is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a target for sputtering alloys or intermetallic compounds.

As ICs become more sophisticated and highly integrated, there is a noticeable tendency for chip dimensions to increase, internal pattern dimensions to become smaller, rounding, and wiring, which is a means of transmitting electrical signals within the chip, to become longer. However, polycrystalline metal silicon thin films are currently used as the wiring material. It is well known that in a polycrystalline silicon thin film, even if impurities are doped to the solid solution limit, the sheet resistance cannot be reduced to less than 20-10 Ω/ell''.

On the other hand, if a high-performance device is assumed to have this sheet resistance value, signal delay cannot be ignored. For this reason, research and development of materials that can replace polycrystalline metal silicon thin films are being actively conducted.

Among them, the book considered to be the most promising is M.

or W silicide thin film. (hereinafter referred to as MoS i 21
Punishment 12 (F), Mo81z, WSh
The membrane can be used to reduce the sheet resistance of polycrystalline silicon metal by almost an order of magnitude, i.e., 2-507 cm"K, with little change in the currently used manufacturing process for polycrystalline metal silicon.

As a method for forming this M□Si2 or WSi 2 film, the method of Dan^ is being considered, but the method using direct current magneton sputtering technology (hereinafter simply referred to as sputtering method) is stable in terms of film quality. This method is being studied the most because it has advantages such as high productivity and easy adoption of a method using a busy holding tool in terms of production technology.

The sputtering of a MoSi2 film will be described in detail below as an example.

The most commonly used method for forming MoSi2 films by sputtering is to mix Mo and s1 powders to have a composition of Mo812, or to form MoSi2 powders in advance into a disk shape as shown in Figure 1. A target 1 is manufactured using a hot press method, and the back surface of this target (the surface opposite to the surface to be sputtered) is metalized with a suitable metal material, and a backing plate 2 & CIn-
It is customary to use it by bonding with 8N alloy material.

However, when we attempted to form a film using this hot press target, we discovered that there was a runner-up as shown below.

(a) Many pores are observed in the target, probably because the target is formed by a hot press method, and the film quality of the sputtered film deteriorates depending on the gas remaining in which pores.

佽) It is difficult to achieve high purity with a nine-target manufactured by the hot press method, and for this reason, easily diffusible ions such as Na −'p K attached during handling are easily incorporated into the deposited Mo812 film. It is unsuitable as a gate metal material.

Radioactive elements in U and Th capes have also been detected, and there are problems such as soft errors occurring when used as a film.

(c) It is difficult to make a large target using the hot press method, and since this target is hard and dull, sputtering power must be applied suddenly, and if the input power is too large, the target will crack and break. Sometimes I put it away. For this reason, the deposition rate is low, which is a major problem in terms of productivity.

The present invention is of stable high quality, excluding the drawbacks as described below.
This is a book that provides targets on which o812 films and the like can be formed.

An example of a dormitory according to the present invention will be explained in detail below.

The most common target shape is circular 4, so
I will explain this using a circular target as an example.

First, fan-shaped small pieces as shown in Fig. 2 are made from high-purity 81 and Mo plate materials, and these Si pieces 11.11' --- and Mo pieces 12.12', -m- are made as shown in Fig. 3. To create a mosaic target by arranging the S
The composition ratio of MO and 81 in the sputtered film is changed by changing the plane angle ratio between the small pieces of Mo and 1 (since it is a fan-shaped beam, the central angle of - in Figure 2 is changed). I can do it.

In order to obtain a silicide film having a composition ratio of Mo81z, the following calculations were performed to determine the surface ratio between Si and MO.

Normal sputtering electric field for Sl and Mo (500~?00V)
Spyp-yield at Y81 W O, 55, YI
It is reported that Ja=0.93. When the respective 9 areas of Sl and Mo are 811°gM, the amount St of sputtering of Sl and Mo is YU x Sst, and the amount of Mo is Y
It is expressed as Mo x SMo.

In order to obtain a silicide film with a composition ratio of Mo8i2, K can be determined as 3.5 in 88 martyrdom 0.93 - 2 x 0.55 since K = 2. , the ratio of the central angle (θ) of the greasy particles should be chosen to be 3.5. If the divided pieces have too large an angle, there is a risk of non-uniformity within the surface of the substrate to be deposited. eye,
A small piece of MO is 8', a small piece of 81 is 2811, and KMo, 8 is used to make a split target with a diameter of 200 dragons.
10 beams of each type were made.

The thickness of the target at this time was 7.1 mm. These M
When sputtering is performed by simply arranging O and Si divided pieces on a backing plate, the surface of the Sl pieces disappears, but when the deposited film is analyzed, it is found that 81% of the film has not been deposited at all. Ta. Therefore, when we measured the resistance between the surface of each small piece of Mo T 8i and the backing plate, we found that for the small MO piece it was less than 0.1 Ω, and for the small piece of 1 Sl it was 100 to several hundred Ω, which was different from the strength of the pressing force K by the presser jig. It changed to Ω. This was thought to be due to the contact resistance between the 8t small piece and the backing plate.

In the case of DC sputtering, the discharge impedance itself is high, ranging from several tens to hundreds of Ω or more, so the resistance value on the target surface is not much of a problem, but in the case of so-called magnetron type sputtering, in which a magnetic field and an electric field intersect, Since the discharge impedance is very small, less than 100, it is considered that the target resistance becomes unbalanced as described above, and K ions flow to the one with the lower resistance during running, and only Mo is sputtered.

In order to improve the peeling, the inventor Hiromu made the following improvements.

First, the 81 piece is made of metallic silicon (approximately 1 to 0.10・α) material that is sufficiently doped with phosphorus (P), arsenic (S), and in some cases antimony (SB) to lower the resistivity. Next, the erosion area (area to be sputtered) of one target is K as shown in Figure 4 of the general KFi, and by taking advantage of the fact that the center and periphery of the target are not eroded, the area that is not eroded can be set appropriately. T! to the backing plate using a suitable fixture. 45.6
It was fixed with the structure shown in the figure. That is, FIG. 5 shows a method of fixing the KSi divided pieces 11. The outer periphery of the divided small pieces is fixed to a backing plate 15 also made of stainless steel or copper using an outer periphery fixing jig 13 made of stainless steel using bolts 16 made of stainless steel. At this time, the bolt 16 and the outer peripheral fixing jig 15 are kept insulated by an insulator 17 made of Albus. The inner periphery of the divided lj4 is also fixed to the backing plate 15 using a central fixing jig 14 made of stainless steel. It is desirable to insert a metal foil 1B between the divided pieces and the backing plate at the time of this fixation, as this will provide tightness and reduce contact resistance.

Figure 6 shows an example of a method for fixing the Mo divided small pieces 12. In this case, if the fixing jig/backing plate comes into direct contact with the MO beam, the target surface resistance will be extremely reduced, so a metal silicon thin plate 19 is placed between them.
．． 20 and 21 could be inserted respectively, and the other configuration was the same as that of the 81 divided pieces. In addition, the fixing means for the queen is the outer circumferential fixing jig 13 #i ring shape, and the central fixing jig 14
is disc-shaped and Z.

Split target made by Jinyo K and assembled 81 +
The surface resistance of each divided piece of Mo was less than a few tens of ohms, and when sputtering was performed using a tarpit under a pressure of 1 x 10 torr, it was 1.000 to 5.
．． High-speed deposition of QOOA/min was possible.

In the divided target of the present invention, it is relatively easy to make the divided small pieces of Sl and Mo highly pure, so that the contamination of the impurities of the ion cape, which is easy to diffuse as described above, can be almost ignored, and the U and Th% Radioactive elements can also be purified to the order of several pPb at the time of raw materials, and there is almost no problem with the desired purity of the divided pieces.

Furthermore, since the target was originally divided into small pieces, there was no possibility that the target would crack and be damaged even if the sputtering power was suddenly applied with high resistance to thermal shock.

When repeated vapor deposition was performed using the divided target of the present invention, a MO8i film with satisfactory film quality was obtained with good reproducibility.

As another example, the back side KA of the divided small piece! 5~50μ
The contact resistance with the backing plate was reduced by depositing m. By doing this, the surface resistance of the 81 piece was reduced to several ohms, and the discharge became more stable.

Above, an example in which divided pieces are arranged alternately in a radial manner has been described in detail, but the divided pieces are appropriately arranged vertically, horizontally and diagonally so that the area of one different type of target material becomes a desired ratio in the vapor deposited film. The same effects as in the above-mentioned example can also be achieved with the divided target.

In yet another embodiment, in order to prevent contamination from the backing plate from diffusing into the plasma (on the migration surface), the divided pieces 11', 1 as shown in FIG.
The two lateral joining surfaces are combined at an angle, or the lateral joining surfaces are combined in a stepwise manner as shown in the striped S diagram, or further,
As shown in FIG. 9, adjacent divided pieces 11 and 12 of the same type
It is preferable to have a structure in which different types of divided pieces are fitted and locked into grooves provided between the two.

Although the example of the MoSi2 vapor deposited film has been described above, the present invention is not limited to this example, and substantially the same Ω action and effect can be achieved with other high melting point metals as described above.

Since the present invention has the above-mentioned configuration, the main effects that can be achieved by the configuration are as follows.

ill Since the hot press method is not used, residual gas is not contained in the target.

(2) High purity target material can be easily assembled.

131 It is easy to manufacture large targets, and there is no risk of damage due to power fluctuations during operation.

(4) A stable and high quality deposited film can be formed.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional sputtering target;
11 is a perspective view of a fan-shaped divided small piece of the present invention, FIG. 5 is a plan view of a target obtained by assembling the fan-shaped divided small piece into a circle, and FIG. 4 is a perspective view showing one erosion area of the fan-shaped divided small piece.
45 and 6 are cross-sectional views illustrating means for fixing the divided small pieces to the backing plate, and FIGS. 7 to 9 are cross-sectional views illustrating the manner in which the divided small pieces are assembled. In the figure: 11.11' ...Silicone divided pieces, 12, 1
2'...Molybdenum divided small pieces. 15-...Outer fixing jig, 14...Central fixing jig. 15... Backing plate, 16... Bolt. 17...Insulator, 18...Metal foil. 19, 20, 21...Kanabe silicon thin plate. Figure 7 Decoy Figure 8 Figure 9

Claims (1)

[Claims] An alloy or intermetallic compound sputter, characterized in that divided small pieces of a sputtering material made of a material of 111 Pa are arranged in alternating traps, and the divided small pieces are mechanically fixed to a backing plate by a holding jig. split target. (2) The divided target according to claim 1, wherein the central angle of the fan-shaped divided small pieces of sputtered materials of different materials is an angle corresponding to the alloy or intermetallic compound to be deposited. (3) The divided target according to claim 1, wherein the lateral joint surfaces of the divided small pieces are inclined surfaces or stepped surfaces. (4) The divided target according to claim 1, wherein different kinds of divided pieces are fitted and locked in grooves provided between adjacent divided pieces of the same type. (5) The divided target according to claim 1, wherein the divided small pieces of high-melting point metal are fixed to the backing plate and the holding jig by interposing thin metal silicon plates on the contact surfaces thereof. (6) The divided target according to claim 1, wherein the divided pieces made of metallic silicon and high melting point whole are fixed to a backing plate via a metallic aluminum thin film or aluminum foil. (7) High melting point metals are molybdenum and tungsten. The split target according to claim 1, which is one of tantalum, titanium, platinum, zirconium, /(nadium, hafnium, and niobium). (8) The metal silicon is doped with phosphorus, arsenic, and antimony in advance. A divided target according to claim 1.