JPS6291470A - Silicon nitride sputtering target and manufacture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] Silicon nitride thin films obtained by sputtering silicon nitride have many industrial uses, especially in the semiconductor industry (for passivation as a diffusion barrier for IINa+, etc.). membrane, (2) oxygen diffusion mask, (3) HIF resistance
It is an important thin film material that is used as a knee mask, +41MNOS gate film, (5) dielectric material for capacitors, etc.

The present invention provides a high-purity silicon nitride sputtering target as a raw material, and aims to industrially and efficiently produce a silicon nitride thin film that can withstand the above uses by sputtering using this target. It is something to do.

[Conventional technology and its problems]

Conventional methods for producing silicon nitride thin films can be broadly classified as follows.

+11 0vD (2
1) Introducing Nu, N)Is, etc. into the sputtering gas
Reactive sputtering (3) Sputtering using silicon nitride as a target material However, method (1) has the drawback of high film deposition rate but high substrate temperature, and method (2) has the disadvantage of high substrate temperature. There is a disadvantage that increasing the stoichiometry of the membrane causes a loss of stoichiometry.

Therefore, method (3) is considered to be advantageous from an industrial perspective, but due to the insufficient characteristics of the target material that can be used in this method, the advantages of method (3) could not be fully demonstrated. There is.

A sputtering target member of silicon nitride and (-) conventionally used il + silicon nitride powder. However, these target members have the following drawbacks (i.e., in the fil target member, the target is located at the lower part of the chamber. It cannot be used with sputtering equipment that has any other structure.Also, during sputtering, some of the powder becomes electrically charged, and the electrostatic repulsion forces cause it to stick to the opposing substrate. In some cases, this may cause defects in the thin film.Also, there were many problems such as the sputtering rate changing over time.Furthermore, the target member of (2) was used.

However, since the bonding force between silicon nitride powders is very weak, (1
) problems often occurred.

The target member (3) is created by adding a metal compound that reacts with silicon nitride, which is the most difficult to sinter, and generates a low-melting glass phase, thereby creating a strong bond between silicon nitride powders. It is something that realizes a union. Since the target member has such high strength, fil, +21
Although these problems have been solved, it is inevitable that the metal compound added as a sintering aid will be mixed into the sputtered film. Such impurities (7) have various negative effects such as diffusion into other thin film layers and deterioration of etching resistance and insulation resistance.

In view of these points, the present invention provides a sputtering target that can industrially and efficiently form a silicon nitride thin film with high purity and few defects, which is different from the conventional technology -c+zm, and a method for manufacturing the same.

[Structure of the invention]

In the present invention, metal impurities are [11% or less and 9% to 100].
To provide a silicon nitride sputtering target having a bending strength of 7 or more, and as a manufacturing method thereof,
Add and mix 1*% by mass or more of silicon powder to silicon nitride powder, and cold-press the obtained powder to form a green compact and L,
Furthermore, the present invention provides a method for producing a silicon nitride sputtering target, characterized in that this green compact is fired at a temperature of 1100° C. or higher in an atmosphere containing nitrogen.

In this way, the sputtering target of the present invention has a metal impurity content of Q, 1ii% or less, thereby minimizing the influence of impurities on various physical film properties during film formation (7). be able to.

At the same time, by having a mechanical strength of 100 to 9/cTIt or more in terms of bending strength, effects such as prevention of scattering of target surface powder due to charging or prevention of damage to the target due to thermal shock during sputtering can be obtained.

Second, such a silicon nitride sputtering target has not previously existed.

Next, a method for manufacturing the target of the present invention will be explained.

First, starting materials and E~ are thoroughly mixed with silicon nitride powder and silicon powder in a predetermined ratio using a ball mill, a light machine, etc. 1. Use something similar. In this case, the proportion of silicon must be 11% or more. This is because if it is less than 1%, it is extremely difficult to obtain the desired mechanical strength of the target even by the following process.

On the other hand, there is no particular limit to the amount of silicon added, but it is preferably 60% or less, more preferably 50 to 40%. This is because if the amount of silicon added exceeds 60%, it will take a very long time to nitride silicon in the following process, and careful attention will also be required to the nitriding temperature, temperature increase rate, etc.

In addition, it is desirable that the purity of the raw material powder is as high as possible t2
It is necessary that the metal impurities be less than 0.1%. Furthermore, the smaller the particle size and the higher the density of the green compact when molded at a constant pressure, the more advantageous it is to easily complete the following process.

There is no specific regulation regarding the oxygen content in the raw material powder, but in this process, the oxygen content in the product target material is determined by the oxygen content in the raw material powder, so by controlling the former, the latter can be controlled. It is also possible to control

Next, the mixed powder thus obtained is molded into a predetermined shape using a die press or the like to form a green compact. The green compact is then fired at a temperature of 1100 DEG C. or higher in an atmosphere containing nitrogen to form a target made of silicon nitride in a chemically atomic ratio.

At the same time, bonds are formed between the silicon nitride particles, and mechanical strength required as a target material is developed.

If the firing temperature at that time is less than 1100° C., it is extremely difficult to nitride silicon. Although high temperature is advantageous in terms of nitriding rate, it also increases the dissociation pressure of silicon nitride, so in order to suppress such a reverse reaction, it is necessary to increase the nitrogen pressure in the atmosphere as necessary. In order to quickly complete the nitriding reaction in an industrially advantageous nitrogen stream, it is necessary to
The most suitable firing temperature is 1800°C. When firing at this humidity, the time required for nitriding is approximately 30 to 180 minutes.

The sintered body thus obtained is cut and finished using a cutting machine such as a diamond cutter or a band saw to obtain a silicon nitride sputtering target in a predetermined shape.

〔Example〕

The present invention will be further explained below with reference to Examples, but the scope of application of the present invention is not limited in any way by these Examples.

Example 1 Commercially available silicon nitride powder (purity 999%, average particle size 1μ, oxygen content 1%) and commercially available silicon powder (purity 999%,
Table 1 shows the average particle size (3μ). Mixing was performed for 30 minutes using a Raikai machine at a ratio of A1 to 50 to obtain 2009 mixed powders.

These were press-molded using a 100φ mold at a pressure of 1 t/crl to obtain a green compact. These were heated to 150 ml in a nitrogen stream.
The powder compact was fired for 1 minute at 0°C. There was almost no dimensional shrinkage of the green compact due to the firing, and a target material of 100φ was obtained. The physical properties of these materials are also shown in Table 1.

When the target obtained by Ya. 6 was sputtered under the following conditions, the film quality, film deposition rate, etc. shown in Table 2 were obtained. Further, even after continuous sputtering for 20 hours at RIF power of 400 W, no damage such as cracking of the target occurred, and the film quality and film deposition rate were stable. Therefore, compared to the case of using a conventional target, the performance is the same or better.

Sputtering method RF magnetron RF power 200 and 400W Gas atmosphere
5×10-' Torr press sputtering time 1
hr Substrate Glass Table 1 Table 2 [Effects of the Invention] The sputtering target obtained by the present invention has a metal impurity content of 0.1% by weight or less, and various physical film properties when forming Kosai 1 are as follows: Minimizes the influence from impurities. At the same time, the bending strength is 9 to 100.
By having a mechanical strength of 7 d or more, effects such as preventing powder on the target surface from flying off due to charging or damage to the target due to thermal shock during sputtering can be obtained.

Claims (2)

[Claims] (1) Metal impurities are 0.1% by weight or less, 100kg/
A sputtering target made of silicon nitride with a bending strength of cm^3 or more. (2) Add and mix 1% by weight or more of silicon powder to silicon nitride powder, cold-press the obtained powder to form a compact, and further press the compact in an atmosphere containing nitrogen. 1100
A method for manufacturing a sputtering target made of silicon nitride, characterized by firing at a temperature of ℃ or higher.