JPH1081962A - Production of ge-te-sb target for sputtering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a Ge-Te-Sb sputtering target for forming thin coating small in abnormal discharge and having a uniform compositional distribution at a low cost by mixing the powder of Ge, Te and Sb having specified particle size at prescribed ratios, filling this powdery mixture into a die and executing sintering at a specified temp. SOLUTION: Ge powder having 1 to 20μm average particle size and Te and Sb powder having 10 to 200μm average particle size are uniformly mixed at prescribed ratios to form into raw material powder. This powdery mixture is filled into a die of graphite and is subjected to pressure sintering at a temp. in which liq. phases are not formed till Ge single phases having the high m.p. are not brought into reaction with Te and Sb as the other elements. The obtd. compacted body is machined and is thereafter fitted to a backing plate. The Ge-Te-Sb series sputtering target forming thin coating free from abnormal discharge and having a uniform compsn. at the time of forming a thin coating layer of a phase changing type disk recording medium by sputtering is produced at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-cost manufacturing method of a Ge-Te-Sb-based sputtering target material used for sputtering a thin film layer of a phase-change optical disk recording medium, and particularly to a target material obtained. The present invention relates to a method for producing a sputtering target material in which abnormal discharge during sputtering is small and the composition distribution of a thin film obtained using the same is uniform.

[0002]

2. Description of the Related Art An alloy containing Te has been put to practical use as a material suitable for a recording medium thin film layer of a phase-change optical disk. This thin film layer is generally manufactured by a sputtering method. The target used in the sputtering method includes a circular or square plate-shaped target material such as an alloy containing Te or the like, and a cooling plate (backing plate) brazed thereto.

Conventionally, target materials have generally been produced by the following powder sintering method. First, the raw material of the target material is heated and melted in a reduced pressure atmosphere or an inert gas atmosphere, and cooled to obtain an alloy ingot. Next, the alloy ingot is pulverized into an alloy powder, put into a graphite mold, and a compact is manufactured by pressure sintering or cold isostatic pressing in an inert gas or under reduced pressure.

When this compact is measured by XRD, a single phase peak of the element used as a raw material is not observed, but a ternary alloy phase peak is recognized. In the case of a Te—Ge—Sb alloy, the structure of the compact obtained by the alloy powder sintering method does not include a single phase of a specific element, and a mixed phase of a binary compound or a single phase of a ternary compound. Is confirmed by EPMA. Such a method of manufacturing a target material using an alloy powder is hereinafter referred to as an “alloy powder sintering method”.

[0005] When no alloy powder is used, each raw material of the target material is ground and mixed to form a uniform mixture, and this mixture is subjected to pressure sintering to form a non-alloy compact. For example, Japanese Unexamined Patent Publication No. 3-180468 and the like. When this compact is measured by XRD, a single-phase peak of the element used as a raw material is observed. Such a method of manufacturing a target material using the mixed powder of the single elements constituting the target is hereinafter referred to as “mixed powder sintering method”.

[0006]

However, the above-mentioned alloy powder sintering method and mixed powder sintering method have the following disadvantages.

In the case of the alloy powder sintering method, Te or Te
Since the alloy containing Ti easily adsorbs oxygen, the oxygen content of the alloy powder containing Te is significantly increased as compared with the oxygen content of the raw material ingot. Since a compact is produced using such an alloy powder, the resulting compact contains a large amount of oxygen.If sputtering is performed with a target using the compact, the target material may crack during sputtering or abnormal discharge may occur. Often occur. Further, the melting and casting process increases the production cost of the target.

In the case of the mixed powder sintering method, a single phase of each element exists in the structure of the compact obtained by the mixed powder sintering method as described above. Since an element having a small sputtering rate and an element having a large sputtering rate are mixed, there arise problems such as an element having a small sputtering rate remaining in the target and a variation in the composition distribution of the obtained thin film.

The present invention has been made in view of the above circumstances, and has a structure in which there is no single phase of an element (hereinafter, referred to as "alloy phase structure"). This is a method in which a compact having a small amount of oxygen can be reduced without performing melting casting because the reduction is performed, and a target material of a Te—Ge—Sb alloy having a uniform alloy phase structure with a low oxygen amount can be used. It is an object to provide a method that can be manufactured at low cost.

[0010]

SUMMARY OF THE INVENTION The Ge-Te-S of the present invention.
The method for producing the b-type sputtering target material includes a Ge powder having an average particle size of 1 to 20 μm and an average particle size of 10 to 200 μm.
μm Te powder and Sb having an average particle size of 10 to 200 μm are uniformly mixed at a predetermined ratio, and this mixed powder is filled in a mold, and Ge reacts with other elements at a lower temperature than a liquid phase is formed. Pressure sintering until the single phase of Ge disappears.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The method of the present invention is intended to reduce the melting point of Ge powder having a high melting point from 1 to 20 μm among the elements constituting the target material.
And the other raw material powders of Te and Sb were adjusted to 10
After adjusting the thickness to 200 μm, all the powders are uniformly mixed to obtain a raw material powder. This raw material powder is filled in a graphite mold, and pressure sintering is performed at a temperature lower than the temperature at which the liquid phase is generated, preferably directly below, until the single phase of high melting point Ge does not react with other elements, The obtained molded body is machined. The target material is bonded to a backing plate and provided for sputtering.

Here, the reason why the particle diameter of Ge is set to 1 to 10 μm is that powder having a particle diameter of less than 1 μm has a large ratio of surface area to volume, so that the amount of oxygen in the powder increases due to surface oxidation. This is because, even if powder having a particle size of more than 10 μm is used, Ge may not completely react with other elements even after pressure sintering, and may remain in the structure of the compact as a single Ge phase.

Further, the particle diameters of Te and Sb are set to 10-20.
The reason for setting the particle size to 0 μm is that the powder having a particle size of less than 10 μm has a large surface area to volume ratio, so that the amount of oxygen in the powder increases due to surface oxidation.
This is because the use of a powder having a size of more than μm makes it difficult to increase the density of the compact.

Further, the pressure sintering is performed at a temperature lower than the temperature at which a liquid phase is formed, in order not to perform liquid phase sintering. By setting the temperature directly below the temperature, the reaction can proceed in as short a time as possible.

[0015]

Embodiments of the present invention will be described below. (Example) A Te-Ge-Sb target was manufactured as follows. First, each of the raw material Te and Sb ingots was ground in ethanol using a cup mill for 1 minute, and sieved to obtain raw material powder having a particle size of 10 to 200 μm. The raw material Ge ingot was pulverized for 10 minutes using a cup mill and sieved to obtain a raw material powder of 1 to 20 μm. Next, these raw material powders were weighed and uniformly mixed by a V blender. This mixed powder was filled in a graphite mold, and was subjected to pressure sintering in an Ar atmosphere at a pressing pressure of 200 kgf / cm ² and a maximum sintering temperature of 370 ° C. for 4 hours. The obtained molded body had an oxygen content of 800 ppm.

Observation of the structure of this compact by EPMA revealed that the structure was Ge-Te, Sb-Te, and Ge.
-Sb-Te type compound, Ge single phase, Sb single phase,
Alternatively, there was no Te single phase. Also, the molded body is represented by X
When measured by RD, no peak of the Ge single phase, Sb single phase, or Te single phase was observed. From these, it can be seen that the reaction between the elements progressed to generate a binary or ternary compound, and the single phase disappeared.

When a sputtering evaluation was performed using this molded body, almost no abnormal discharge occurred during the sputtering, and the composition distribution of the obtained thin film was uniform and favorable.

Comparative Example 1 A Te—Ge—Sb target was manufactured by an alloy powder sintering method. Te, G as raw materials
e, each ingot of Sb was weighed, and 80
Heated to 0 ° C and cast after melting, Te-Ge-S
A b-based alloy was used.

Next, the alloy was pulverized in ethanol using a cup mill and sieved to obtain a raw material powder of 1 to 200 μm. Next, this raw material powder was filled in a graphite mold, and pressure sintering was performed at a pressing pressure of 300 kgf / cm ² and a maximum sintering temperature of 500 ° C. for 4 hours in an Ar atmosphere. The oxygen content of the obtained molded body was as large as 3500 ppm.

When the structure of this molded product was observed by EPMA, the structure was a Ge—Sb—Te-based compound.
No single phase, Sb single phase, or Te single phase was observed.
Further, when the molded body was measured by XRD, it was confirmed that the Ge single phase, S
No peak of b single phase or Te single phase was observed.

When a sputtering evaluation was performed using this compact, a large amount of abnormal discharge occurred during the sputtering. The composition distribution of the obtained thin film was uniform and good.

Comparative Example 2 A Te—Ge—Sb target was manufactured by a mixed powder sintering method. First, the raw materials Te and G
e, each ingot of Sb was crushed in ethanol for 1 minute using a cup mill, and sieved to a particle size of 10 to 200 μm.
m of the raw material powder. Next, each of these raw material powders was weighed and uniformly mixed. This mixed powder is filled in a graphite mold,
Pressing pressure 200kgf / cm ² , maximum sintering temperature 300 ° C
For 4 hours in an Ar atmosphere. The obtained molded body had an oxygen content of 800 ppm.

When the structure of this compact was observed by EPMA, the structure was Ge-Te, Sb-Te, and Ge.
The mixed phase was a -Sb-Te-based compound phase, a Ge single phase, a Sb single phase, and a Te single phase. In addition, XRD
As a result, peaks of a single phase of Ge, a single phase of Sb, and a single phase of Te were observed.

When the evaluation of sputtering was performed using this molded product, the distribution of the composition of the obtained thin film varied, although almost no abnormal discharge occurred during sputtering.

[0025]

According to the present invention, a Ge—Te—Sb based sputtering target material having an alloy phase structure and having a small amount of oxygen due to the elimination or reduction of adsorbed oxygen during pressure sintering can be reduced. It can be manufactured at low cost, and when it is sputtered using this, abnormal discharge is reduced and the composition distribution of the obtained thin film becomes uniform.

Claims (1)

[Claims] 1. A Ge powder having an average particle size of 1 to 20 μm, a Te powder having an average particle size of 10 to 200 μm,
200 μm of Sb is uniformly mixed in a predetermined ratio, and this mixed powder is filled in a mold and Gb is mixed at a lower temperature at which a liquid phase is formed.
A method for producing a Ge-Te-Sb-based sputtering target material, wherein pressure sintering is performed until e reacts with another element to eliminate a single phase of Ge.