JPH03183765A - Conductive sialon target material - Google Patents

Abstract

PURPOSE:To obtain a conductive sialon target material capable of forming a superior protective film by a compounding a beta'- or alpha-sialon phase of a specific composition, a phase of the nitride of the group IVa elements, and an amorphous grain boundary layer in which Y, Si, Al, and N are allowed to exist. CONSTITUTION:This conductive sialon target material is composed of a combined phase consisting of a beta'-sialon phase represented by Si6-zAlzOzN8-z (where 0<z<=4.2) and/or an alpha-sialon phase represented by Mx(Si,Al)12(O,N)16 [where 0<x<2 and M means Li, Mg, Ca, Y, and rare earth elements (excluding La and Ce) ], a phase of the nitride of the group IVa elements, and an amorphous grain boundary phase in which Y, Si, Al, and N are allowed to exist. This target material can form, e.g., a superior protective film for magneto-optical recording medium. Further, this target material has electric conductivity and enables film formation at a relatively low temp. and D.C. sputtering. Moreover, it is preferable that TiN is used by >30-<70vol.% as the above nitride phase.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a sputtering target and a protective film material used for forming a protective film on a magneto-optical recording medium.

[Conventional technology]

Conventionally, as protective film materials for magneto-optical disks, Sin,
Sin, AIN (Ota et al.: Journal of the Japanese Society of Applied Magnetics 8.2
(1984) P, 93), St, N4 (Torazawa et al.: Optical Memory Symposium °86 Proceedings P, 87), 5iAI
ON (Asano et al.: Optical Memory Symposium '86 Proceedings P
, 51), etc. have been proposed, and films are formed on substrates by sputtering using target materials mainly having these compositions. The protective film is required to i) have good protection performance for the recording medium, and it) be transparent and have a high refractive index. [Problems to be Solved by the Invention] However, forming the above-mentioned protective film has the following drawbacks in film formation. That is, (1) SiO and 5i0. Oxygen is easily liberated from the film, reacts with the rare earth metal element of the rare earth metal-transition metal alloy thin film used as a recording medium, and selective oxidation occurs, resulting in deterioration of magneto-optical properties. (2) Since SiO and Sin are insulators, they are deposited by RF sputtering using a high-frequency power source. However, in the case of RF sputtering, the substrate temperature increases significantly, so polycarbonate, which is usually used as a substrate material, is used for film formation. If a resin such as CPC is used, there are problems such as deformation of the substrate. AIN, SiN, 5iAION, and the like have been proposed and put into practical use as protective film materials that improve characteristic deterioration due to free oxygen. For forming these protective films, for example, 5iAION
In this case, SiO and AI are used as target materials, and they are formed by reactive sputtering in an atmosphere of argon and nitrogen gas. However, in such reactive sputtering, the ratio of Si to AI tends to fluctuate, making it difficult to stably form a protective film with a desired composition. As a means to solve the above-mentioned problems, Japanese Patent Laid-Open No. 63-223169 discloses a method in which a 5iAION sintered body having a desired composition is formed by sputtering using a target material. However, 5
Since the iA1ON sintered body is an insulator like Sin, it can only be formed into a film by high-frequency sputtering, and it is difficult to apply it to film formation on PC boards where an increase in substrate temperature is a problem. be. The purpose of the present invention is to provide excellent protective films for magneto-optical recording media,
Another object of the present invention is to provide a sialon target material having conductivity that enables direct current sputtering that allows film formation at relatively low temperatures. [Means for Solving the Problems] As a result of studies to solve the above problems, the present inventors mixed a sintering aid and a group IVa nitride in a predetermined ratio to silicon nitride. After that, β′ obtained by sintering this
- a sialon phase and or an α-sialon phase and a group IVa nitride phase and Y, SL. If a composite consisting of an amorphous grain boundary phase in which AI and N exist is used as a target material, both high frequency and direct current sputtering film formation is possible, and it has excellent properties as a protective film for magneto-optical disks. It was found that That is, the present invention provides S i, -z A l engineering Oz N
-z (However, 2 is β expressed as O (Z≦4.2)
'-Sialon phase and Mx(SL, Al)+*
(0,N)m@(0<X<2.M is Ij, Mg, Ca,
α-sialon phase represented by Y, rare earth elements (La, Ca excluded ()) and IVa group nitride phase, and Y, Si+AI
, a conductive sialon target material characterized by being composed of a composite phase of an amorphous grain boundary phase in which N is present, preferably the IVa group nitride phase is TiN, and the volume %
is more than 30% and less than 70%. In order to produce the conductive sialon target material of the present invention, for example, silicon nitride, two or more sintering aids in an amount i of 6 to 25 by weight relative to the silicon nitride, the silicon nitride, the sintering aid, and It can be obtained by mixing more than 30 volumes and less than 70 volumes of titanium nitride in total and then sintering the mixture. Furthermore, the sintering aids are preferably Y, O, and A.
It is preferable that the total weight of I, O, is 4 to 18 weight 1, and the polytype of AIN is 2 to 7 weight i. On the other hand, titanium nitride preferably has a body volume of 40-60. Here, the reason why it is preferable that the total addition amount of Y, O, and Al, O is 4 to 18 weight i is that if it is less than 4 weight 1, the sintered body will not be densified, and such materials will not be densified. This is because when used as a sputtering target, abnormal discharge occurs during sputtering. On the other hand, if it exceeds 18% by weight, the amount of oxygen in the film becomes excessive and the protective performance of the sputtered film deteriorates. In addition, the reason why it is preferable to set the amount of polytype of AIN to 2 to 7 weight i is that if the amount is less than 2 weight i, the protection performance of the sputtered film is insufficient, and if it exceeds 7 weight 2, the sinterability will decrease. This is because the target material cannot have sufficient density. In the present invention, the reason why the volume of titanium nitride is more than 30% and less than 70% of the conductive sialon target material is that if it is less than 30%, the discharge stability during DC sputtering is poor, and if it is more than 70%, the sintered body This is because it does not become dense. From the viewpoint of discharge stability during DC sputtering, the volume of titanium nitride is preferably 40 to 60%. Since the above-mentioned silicon nitride is difficult to sinter, a sintering aid is added thereto. Preferred sintering aids are Y, 03, AI, O,...
These include AIN, AIN polytype (SL and O dissolved in AIN), MgO, etc. Among these, AI, O,...
AIN, AIN polytype forms β'-sialon and/or α-sialon by mixing and sintering with silicon nitride. Among them, the preferred sintering agents are Y, O, and AIN.
The conductive sialon target material of the present invention, which is composed of a combination of polytype and Al, O, is composed of three phases: a β'-sialon phase and/or an α-sialon phase, a TiN phase, and a grain boundary phase. , Y, Si in the grain boundary phase
. Al, O, and N are present, forming an amorphous phase. This grain boundary phase allows up to 70% of TiN particles to impart electrical conductivity.
Sintering progresses well even when the content is less than or equal to a large amount. An example of a method for manufacturing a sialon target according to the present invention will be described below. The mixed powder of silicon nitride, sintering aid, and titanium nitride can be directly formed into a predetermined shape by dry or wet methods. If molded using wet method,
There are two methods: sintering in a nitrogen-containing gas atmosphere under normal pressure or pressurization after drying, or filling raw material powder into a die of a predetermined shape and hot pressing. You can. The pressure of nitriding gas is 300kg70 from the viewpoint of pressure resistance of the furnace.
It is preferable to keep it to a certain extent. The sintering temperature is usually 1,600 to 1,900°C, but the reason is that densification during sintering is insufficient at 1,600°C;
This is because silicon nitride decomposes when the temperature exceeds 900°C. A preferred sintering temperature range is 1650-1800°C. The sintered body obtained by the present invention can be further densified by performing HIP treatment after sintering, and the discharge stability during sputtering is improved. [Example] Examples are shown below. Example 1 As sintering aids, 9 weight i of Y, O, 6 weight i of AI,
O, and AIN polytype of 4 wt. The granulated mixed powder soaked in water was filled into a mold and molded under a pressure of 1 ton l-. This is 1750℃
, sintered in a nitrogen atmosphere at 1 atm for 1 hour. A target material for film formation evaluation of φLot X 3t was processed from the obtained sialon sintered body. For film formation evaluation, a film was formed on a polycarbonate substrate having a thickness of 1 aun using a magnetron type sputtering apparatus having a radio frequency (RF) power source and a direct current (DC) power source. The film forming conditions are output 5 when using a high frequency power supply.
1 J/cn, when using a DC power supply, the Ar gas pressure was 500 mm, the Ar gas pressure was 5.times.1 O-1 torr, the distance between the target and the substrate was 70 III11, and the substrate and target were opposed to each other. In addition, as a comparative example, 5iA1ON, AIN, Si, N
4. Film formation evaluations of Sin and SiO targets were also conducted at the same time, and the film formation evaluation results are shown in Table 1. The conductive sialon of the present invention can be sputtered with either high frequency or direct current, and especially when sputtered with direct current, it may cause damage (warpage, warping, etc.) to the polycarbonate substrate.
It was found that there was very little bending. On the other hand, it was found that the target material of the comparative example could only be used for high frequency sputtering and caused great damage to the substrate. Table 1: DC...Direct current RF...High frequency O...Discharge ×...FIG. 1 shows a scanning electron micrograph of the conductive sialon target material obtained without discharging. In FIG. 1, the white layer is a TiN phase, and the black charcoal hue is a β'-sialon phase.
The white layer is the grain boundary phase. Next, the performance of various protective films was investigated using a pre-group (with guide grooves) glass disk substrate as the substrate. The film structure of the disc is glass substrate/protective film (first layer)/
Tb-Fe-Go (magnetic layer)/protective film (second layer). The protective film thickness of the first layer is 700, Tb-Fe-Co1
Films were formed by sputtering with a thickness of 1,000 layers and a thickness of 1,200 layers for the second layer. In the protection performance evaluation test, each disk was kept in a constant temperature and humidity chamber at 90° C. and 60% relative humidity, and the change in C/N ratio over time was measured. Figure 2 shows the evaluation results of the protection performance test. The conductive sialon of the present invention is a general sialon (hereinafter referred to as 5iAION) which is said to have good protection performance, A I N ,
It can be seen that it has the same performance as S 1m N 4. Example 2 5i, N4 powder, Y, 0. Powder, At, O, powder, AI
Using N polytype powder and TiN powder, Y, O, +A
The sintered bodies were mixed in compositions with various amounts of I, O, and AIN polytype and sintered in the same manner as in Example 1. The sintered bodies were evaluated for sintered density, discharge stability during DC sputtering, and protective film performance. In this case, the amount of TiN was 45% by volume. The results are shown in Table 2. From this result, in the present invention,
y, o, +AI, 0. ．． It can be seen that the amount of the AIN polytype is preferably 4 to 18% by weight and 2 to 7% by weight S, respectively. Example 3 After compounding with the composition of sisN*-in amount % (Y, O, + Al, O,) - 3 wt% AIN polytype, various volume percentages of TiN were added and sintered in the same manner as in Example 1. However, evaluation was performed in the same manner as in Example 2. The results are shown in Table 3. From this result, it is clear that the content of TiN is preferably more than 30 volumes and less than 70 volumes. [Effects of the Invention] According to the present invention, it is possible to perform DC sputtering with little damage to a resin substrate, and to form a conductive sialon film having excellent protective performance as a protective film for a magneto-optical recording medium.

[Brief explanation of drawings]

FIG. 1 is a photograph taken by a scanning electron microscope showing an example of the structure of the conductive sialon target material according to the present invention;
FIG. 2 is a diagram showing the change over time in the C/N ratio of a film formed by sputtering using the target of the present invention. Figure Structure photograph of target material (Elf)) N/F Procedural amendment (method) % formula % 1. Display of case Heisei Patent Application No. 22361 2. Name of invention Conductive SiAlON target material 3. Make amendments patent related to the case

Claims (1)

[Claims] 1 Si_6_-_ZAl_ZO_ZN_3_-_Z(
However, Z is β'-sialon phase expressed as 0<Z≦4.2) and or Mx(Si,Al)_1_2(O,
N)_1_6(0<X<2, M is Li, Mg, Ca, Y
, rare earth elements (excluding La and Ce)) and the IVa group nitride phase, as well as Y, Si, Al, and N.
A conductive sialon target material characterized by being composed of a composite phase of an amorphous grain boundary phase in which . 2 The IVa group nitride phase is TiN, and its volume % is 3
The conductive sialon target material according to claim 1, which has a content of more than 0% and less than 70%.