JPH093638A - Sputtering target and sputtering method - Google Patents

Abstract

PURPOSE: To form a sputtering film which is free from any generation of blackened projection phenomenon on the surface of a target, and stable and excellent in quality by joining the target through a conductive insulation layer whose heat transfer coefficient is specified. CONSTITUTION: A conductive insulation layer 3 whose heat transfer coefficient is 5.0-1250W/m<2> .K, and preferably whose coefficient of thermal conductivity is 2.5×10<-3> to 50W/mK is interposed between a target 1 and a packing plate 5, and fixed by adhesive layers 2, 4. The insulation layer 3 preferably contains the aggregates consisting of the solid substance to withstand the temperature rise, e.g. silicone resin, polyimide resin, fluororesin, metal or inorganic matter. The target 1 is preferably ITO, ZnO, metallic silicate, etc., and the sputtering is preferably achieved under the condition of 0.2-4.5W/cm<2> in current density.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering target (hereinafter simply referred to as a target) and a sputtering method.

[0002]

2. Description of the Related Art A target is composed of a target material and a backing plate, and has been widely used as a raw material for producing a thin film by sputtering such as a transparent conductive film, a thin film magnetic disk, a surface treatment of glass and a film.

[0003]

[Problems to be Solved by the Invention] These targets,
In particular, ITO (In ₂ O ₃ —SnO ₂ ) has a problem in use in recent years. 1) The surface of the target material becomes black as the usage time becomes longer, and 2) Protrusions are generated. It is known that a phenomenon occurs, 3) the film formation rate decreases with the above phenomenon, and 4) arcing and particles occur.

Due to these phenomena, when a conventional target is used, a stable and high-quality I
There is a problem that a TO film cannot be obtained. Therefore, when forming a sputtering film such as an ITO film, it is necessary to remove the black protrusions on the surface of the target material after a certain period of time in order to improve productivity. A problem similar to this is becoming a problem also in zinc oxide and tin oxide, especially in a silicide-based target material.

In the sputtering apparatus used as a mass production machine, the frequency of the above-mentioned work of removing the black protrusions greatly affects the productivity. Therefore, there is a demand for a long-life target that can continuously and stably obtain a high-quality ITO film with little or no removal work.

[0006] As a measure for extending the life of these targets, increasing the density of the targets can be mentioned, but it is known that the phenomenon of forest blackening also occurs in the high density targets.

In view of this, Japanese Patent Laid-Open No. 5-345973 discloses a method for producing a transparent conductive film by a sputtering method using an ITO target material, in which the surface of the target material is heated to 290 to 600 ° C. Proposed. In this manufacturing method, a heater, a hot plate, a high-frequency induction heater, a lamp heating, a laser beam heating, etc. are exemplified as the heating means for the surface of the target material, but these methods are used in the currently commonly used sputtering apparatus. Is not realistic in terms of versatility and cost.

A technique for heating a target in sputtering for forming a thin film is disclosed in Japanese Patent Laid-Open No. 1633/1990.
No. 68 publication. In this technique, in an easily oxidizable metal such as tellurium, in order to correct the change in the oxide reaction rate due to the reaction between tellurium and oxygen in plasma, in addition to this reaction, tellurium and oxygen are heated by heating the target. It was also combined with the oxidation reaction by the heat of, and was by a very special means.

An object of the present invention is to prevent the blackening of forests such as blackening of the target material and the formation of protrusions even if the usage time is long, and to provide a stable and high-quality film over a long period of time. It is an object of the present invention to provide a target which can form a sputtering film and can be practically used at low cost, and a sputtering method using the target.

[0010]

The present invention has a heat transfer coefficient of 5.0 to 5.0 between the target material and the backing plate.
A sputtering target characterized by interposing a conductive heat insulating layer of 1250 W / m ² · K and the target, and a power density of 0.2 W / cm ^{2 to} 4.5 W
Provided is a sputtering method, which is performed under the condition of / cm ² .

[0011]

In the target of the present invention, the heat transfer coefficient between the target material and the backing plate is set to 5.
The range is 0 to 1250 W / m ² · K, and an appropriate heat transfer coefficient is selected from this range according to the conditions such as the power density during sputtering.

By doing so, the temperature of the target can be further raised under the same use condition as compared with the target in the conventional method, and therefore the target material of the target material knocked out by the argon ion when the target is used. It is possible to suppress redeposition, and it is possible to suppress surface blackening of the target material and formation of projections which are considered to be caused by redeposition.

Further, it is possible to suppress or eliminate the decrease of the film forming rate and the generation of arcing and particles which are caused by the above phenomenon.

Therefore, by eliminating the above phenomenon, it becomes possible to form a stable and high quality sputtering film for a long time.

A normal target is composed of a target material 1, an adhesive layer 7 and a backing plate 5, as shown in the cross section of FIG. On the other hand, in the target of the present invention, as shown in FIG. 2 which is a cross-sectional view of FIG. 1 (plan view), a conductive heat insulating layer 3 is formed between the target material 1 and the backing plate 5, and the layer is formed. Has a cross-sectional structure in which the adhesive layers 2 and 4 are fixed.

Examples of the target material used in the target of the present invention include metal silicides such as MoSi ₂ and WSi, and ITO and ZnO containing In ₂ O ₃ and SnO ₂ as main components. Among them, a target material made of ITO or metal silicide containing In ₂ O ₃ and SnO ₂ as main components is preferably used.

The target material composed of the above materials is
For example, although it has a disk shape with a thickness of about 6 mm and a diameter of about 150 mm, its shape and thickness can be arbitrarily changed depending on the purpose of use of the target.

The backing plate material used in the target of the present invention is, for example, copper (C
u), stainless steel, and the like, of which Cu and Cu alloys, particularly oxygen-free copper, are preferably used.

The backing plate made of the above material is usually similar in shape to the target material, for example, a disk shape having a thickness of about 10 mm and a diameter of about 200 mm, but its shape depends on the purpose of use of the target. And the thickness can be arbitrarily changed.

As the adhesive used for adhering the target and the backing plate as described above, for example, graphite-containing paste, silver-containing paste, indium, etc. are preferably used.

In the present invention, as shown in FIG. 2, the conductive heat insulating layer 3 having a specific heat transfer coefficient is formed between the target 1 and the backing plate 5 by using each of the above materials. Then, the layer is fixed by the adhesive layers 2 and 4 to form a target.

As a method of adhering and fixing the target material, a method of adhering and fixing the portion of the adhesive layer 4 in FIG. 2 with an In-based low melting point metal is preferable. This method has an advantage that the used target material can be easily peeled off. Regarding the part of the adhesive layer 2, this part is 150 ° C. to 600 ° C.
In-based alloys are not preferable because the temperature is around 0 ° C., and adhesives containing other conductive powders are preferable.

Various problems at the time of film formation such as the forest blackening phenomenon of the target material of the prior art, which is to be solved by the present invention, are remarkable particularly in the sputtering method using direct current (DC). The DC sputtering method requires that the space between the target material and the backing plate is electrically conductive. Therefore, the heat insulating layer 3 in the target of the present invention needs to have conductivity.

The substance forming the conductive heat insulating layer can be used in various states such as gas, liquid or solid, but since it is used in vacuum and the temperature of the heat insulating layer rises. It is suitable to use a solid substance as an aggregate. Examples of these solid substances include resins, metals and inorganic substances. In order to achieve the object of the present invention, since the heat insulating layer is partially heated to a high temperature of 150 ° C. to 600 ° C., a heat insulating layer made of a heat resistant resin such as a silicone resin, a polyimide resin, a fluorine resin, a metal or an inorganic substance is used. preferable.

Generally, one having a low thermal conductivity, for example, oxide ceramics is generally an insulating material. When these materials are used as the heat insulating layer, it is necessary to mix a conductive substance into these materials or use the end portion of the target or the like to establish conduction.

When the target is used at a particularly low power density, the target material needs to have a low thermal conductivity in order to achieve the object of the present invention. Therefore, the aggregate of the heat insulation layer is porous. Alternatively, it is preferable that the heat insulating layer itself has a multilayer structure.

Further, the larger the distance between the heat insulating layer or the target material and the backing plate, the worse the heat transfer from the target material to the backing plate, so that a wide variety of heat insulating materials can be selected. Due to the structure of the sputtering device, the distance between the target material and the heat insulating layer or between the heat insulating layer and the backing plate is practically in the range of 0 mm to 20 mm. If the space is longer than this, it is not realistic because the device needs to be modified.

The thermal conductivity of the conductive heat insulating layer 3 is 2.5 × 1.
0 ^{-3 to} 50 W / m · K is preferable, and when the thermal conductivity is less than 2.5 × 10 ^-3 W / m · K, the target temperature at the time of sputtering is under normal sputtering conditions. It is not preferable because it rises too much and the target material is cracked and the influence of the radiant heat on the substrate cannot be avoided. On the other hand, the thermal conductivity is 50 W / mK
When it exceeds, the temperature of the target does not rise to a temperature range in which sputtering is efficiently performed during sputtering, which is not preferable.

Further, the heat transfer coefficient between the target material and the backing plate is 5.0 to 1250 W / total as a total of the heat insulating layer and the adhesive layers arranged on both surfaces thereof.
It is preferably m ² · K. The heat transfer coefficient is 5.0
When it is less than W / m ² · K, the target temperature during sputtering rises excessively under normal sputtering conditions, which is not preferable because the target material is cracked and the effect of radiant heat on the substrate cannot be avoided. . On the other hand, if the heat transfer coefficient exceeds 1250 W / m ² · K, the temperature of the target does not rise to a temperature range in which sputtering is effectively performed during sputtering, which is not preferable.

In sputtering, the temperature of the target, particularly the temperature of the erosion region, is the power density applied during sputtering, the target material, the adhesive layer (the number of layers = n layers), the thermal conductivity of each of the backing plates, and the target material. And the adhesive layer, between the adhesive layer and the backing plate, and between the backing plate and the cooling water, the heat transfer coefficient and the temperature of the cooling water largely control the target. It is preferable that the heat transfer coefficient (or the thermal conductivity of the heat insulating layer) between the material and the backing plate is variously changed within the above range. The relationship between the above factors is simply expressed by the equation (1).

[0031]

Embedded image

Here, Q is the power density (W / m ² = 10 ⁴
W / cm ^2), hw is the heat transfer coefficient between the coolant and the backing plate ^{(W / m 2 · K)} , h0 is the heat transfer coefficient between the target material and the backing plate (W / m ² ·
K) and xi are the thicknesses (m = 1) of the target materials, adhesive layers, backing plates, and other constituent materials that make up the target.
0 ³ mm), λi is the thermal conductivity (W / m ·
K) and Ts are the surface temperature (K) of the target material, and Tw is the temperature (K) of the cooling water at the interface of the backing plate.
By transposing equation (1) into equation (2), it is clear that the temperature of the target material can be controlled by the heat transfer coefficient and / or the thermal conductivity of the constituent material of the target, the power density, and the temperature of the cooling water.

[0033]

Embedded image

Here, the power density is determined by the material of the target material and the sputtering, depending on the purpose of use of the object, that is, the film formed on the substrate. In addition, the temperature of the cooling water is usually 20 ° C. because of the restriction such as cracking and dropping of the target material caused by the cooling water. Therefore, if the target material and the power density are known, the temperature of the adhesive layer can be easily adjusted. The adhesive layer whose heat transfer coefficient is controlled can be specified.

If the temperature of the cooling water is made extremely high, the condition of the present invention is deviated. However, the upper limit of the cooling water temperature is limited because of the cracking of the target material, the falling of the target material, and the large influence of the radiant heat of the substrate. Further, if the cooling liquid temperature is remarkably lowered, for example, liquid nitrogen is used, the condition of the present invention is deviated, but this is not practical.

[0036] Thus, for example, in a 0.6 W / cm less than ² power density 0.2 W / cm ² or more during sputtering, the heat transfer coefficient between the target material and the backing plate of the target of the present invention is 5. 0 W / m ² · K
It is preferably 37.5 W / m ² · K or less.

Power density of 0.6 W / cm ² or more and 1.4 W
When it is less than / cm ² , the heat transfer coefficient between the target material and the backing plate of the target of the present invention is 1
2.5W / m ² · K or more 75.0W / m ² · K or less.

Power density is 1.4 W / cm ² or more and 2.0 W
When it is less than / cm ² , the heat transfer coefficient between the target material and the backing plate of the target of the present invention is 25.
W / m ² · K or more 125W / m ² · K or less.

Power density of 2.0 W / cm ² or more and 4.5 W
If it is less than / cm ² , the heat transfer coefficient between the target material and the backing plate of the target of the present invention is ^{3 or} less.
7.5W / m ² · K or more 1250W / m ² · K or less.

The other conditions for sputtering are the same as in the prior art and are not particularly limited.

[0041]

【Example】

[Example 1] Using an ITO target material 1 having a density of 95% obtained by adding 10% by weight of SnO ₂ to In ₂ O ₃ , a metal having a thermal conductivity of 25 W / m · K and a thickness of 1 mm as shown in FIG. T
i is interposed as a heat insulating layer 3, and the heat insulating layer 3 and the ITO target material 1 are bonded to each other with an adhesive 2 having silica and aluminum as a base material, and the heat insulating layer 3 and the Cu backing plate 5 are joined together. In the space, 0.2 mm-thick In was used for adhesion to form the target of the present invention. The heat transfer coefficient between the target material 1 and the backing plate 5 is 70 W.
/ M ² · K.

Using the above target, a power density of 1.0
Sputtering was performed at W / cm ² and a sputtering pressure of 5 mmtorr. The surface of the target material 1 after continuous use for 40 hours was evaluated, and a schematic diagram of the erosion part thereof is shown in FIG.
Shown in As is apparent from FIG. 3, the protrusions near the erosion were reduced as compared with FIG. 7 showing the result of Comparative Example 1.

Example 2 Using the same ITO target material 1 as in Example 1, SiO ₂ and Al ₂ O ₃ coated with a graphite paste having a thermal conductivity of 5.0 W / m · K and a thickness of 3 mm.
Except that the system ceramics is interposed as the heat insulating layer 3.
A target of the present invention was obtained in the same manner as in Example 1. The heat transfer coefficient between the target material 1 and the backing plate 5 was 25 W / m ² · K. The other conditions were the same as in Example 1. The surface of the target material 1 after continuous use for 40 hours was evaluated in the same manner as in Example 1, and a schematic diagram of the erosion portion thereof is shown in FIG. As is clear from FIG.
No generation of protrusions near the erosion could be confirmed.

[Example 3] The same ITO target material 1 as in Example 1 was used, as shown in Fig. 2, to which a 1 mm-thick PTFE (polytetrafluoroethylene) having a specific resistance of 0.1 Ω / cm was provided. Between the heat insulating layer 3 and the ITO target material 1 using a carbon-based adhesive as the adhesive layer 2 between the heat insulating layer 3 and the ITO target material 1, and between the heat insulating layer 3 and the backing plate 5. As the adhesive layer 4 is In
Using 0.2 mm, they were adhered to each other to obtain a target of the present invention. This target material 1 and backing plate 5
The heat transfer coefficient between and was 1000 W / m ² · K.

Sputtering was performed in the same manner as in Example 1 except that the power density was 4.0 W / cm ² . The surface of the target material 1 after continuous use for 40 hours was evaluated, and a schematic view of the erosion portion thereof is shown in FIG. FIG.
As is clear from Fig. 7, the protrusions near the erosion are shown in Fig. 7.
It was reduced compared to.

Example 4 Using a WSi ₂ target material, a graphite paste having a thermal conductivity of 5.0 W / m · K and a thickness of 3 mm was applied to the SiO ₂ and Al ₂ O ₃ -based ceramics as a heat insulating layer 3 A target of the present invention was obtained in the same manner as in Example 1 except that the target was used as the target. The heat transfer coefficient between the target material 1 and the backing plate 5 is 25 W / m.
It was ² · K. Other conditions were the same as in Example 1, and sputtering was performed. The target surface after continuous use for 40 hours was evaluated, and a schematic diagram of the erosion portion thereof is shown in FIG. As is clear from FIG. 6, the generation of protrusions near the erosion could not be confirmed.

[Comparative Example 1] The same ITO target material as in Example 1 was adhered to the backing plate 5 without interposing the heat insulating layer 3 as shown in FIG. Sputtering was performed using this target to form an ITO film on the substrate.
The heat transfer coefficient between the target material 1 and the backing plate 5 was 12500 W / m ² · K. The power density during sputtering is 2.5 W / cm ² , and the sputtering pressure is 5 mmtorr. The surface of the target material 1 after continuous use for 40 hours was evaluated, and the erosion part thereof is schematically shown in FIG. 7. As is clear from FIG. 7, many projections were generated in the vicinity of erosion, and forest blackening had occurred.

[0048]

EFFECTS OF THE INVENTION According to the present invention, it is possible to prevent a decrease in the film formation rate due to the generation of black protrusions generated during the sputtering of a conventional ITO target, and to prevent arcing and cracking. Can be suppressed. Therefore, according to the present invention, it is possible to continuously manufacture a thin film having good and constant characteristics without cleaning the target.

As described above, the running cost required for sputtering film formation can be significantly reduced, and the effect can be obtained by improving the target side. Therefore, there is no need to improve or modify the equipment, and the sputtering thin film can be manufactured at a low cost. Can be supplied to.

Since it is possible to bond the target material and the heat insulating layer at room temperature, the cost required for bonding can be greatly reduced after the first time, that is, the increase in target cost can be suppressed. Or the cost of the target can be reduced.

[Brief description of drawings]

FIG. 1 is a plan view of a target of Example 1.

FIG. 2 is a sectional view of the target of Example 1.

FIG. 3 is a schematic diagram of a target surface after 40 hours of use in Example 1.

FIG. 4 is a schematic view of a target surface after 40 hours of use in Example 2.

FIG. 5 is a schematic view of the target surface of Example 3 after 40 hours of use.

FIG. 6 is a schematic view of a target surface after 40 hours of use in Example 4.

FIG. 7 is a schematic view of a target surface after 40 hours of use of Comparative Example 1.

FIG. 8 is a sectional view of a conventional target.

[Explanation of symbols]

 1: Target material 2: Adhesive layer between target material and heat insulating layer 3: Heat insulating layer 4: Adhesive layer between heat insulating layer and backing plate 5: Backing plate 6: Black protrusion (nodule) 7: Between target material and backing plate Adhesive layer

Claims (5)

[Claims] 1. A sputtering target, wherein a conductive heat insulating layer having a heat transfer coefficient of 5.0 to 1250 W / m ² · K is interposed between the target material and the backing plate. 2. The thermal conductivity of the conductive heat insulating layer is 2.5 × 10 ^−3.
The sputtering target according to claim 1, having a W / m · K or more and 50 W / m · K or less. 3. The sputtering target according to claim 1, wherein the conductive heat insulating layer contains at least one selected from the group consisting of silicon resin, polyimide resin, fluororesin, metal and inorganic material as an aggregate. . 4. A target material is ITO (In ₂ O ₃ —SnO ₂ ) containing In ₂ O ₃ and SnO ₂ as main components, and ZnO.
And at least one selected from the group consisting of metal silicides
The sputtering target according to any one of claims 1 to 3, which is composed of one kind of material. 5. The sputtering target according to claim 1, which has a power density of 0.2 W /
A sputtering method, characterized in that sputtering is performed under the condition of cm ^{2 to} 4.5 W / cm ² .