CN111850489B

CN111850489B - Intermediate material of target material, forming method thereof and device for realizing forming method

Info

Publication number: CN111850489B
Application number: CN202010742327.1A
Authority: CN
Inventors: 韩刚; 程兴德; 韩启航
Original assignee: Jiangsu Jicui Advanced Metal Material Institute Co ltd
Current assignee: Jiangsu Jicui Advanced Metal Material Institute Co ltd
Priority date: 2020-07-29
Filing date: 2020-07-29
Publication date: 2023-01-24
Anticipated expiration: 2040-07-29
Also published as: CN111850489A

Abstract

A target intermediate material, a forming method thereof and a device for realizing the forming method are provided, wherein the forming method of the target intermediate material comprises the following steps: providing a plasma torch having a plasma therein; and introducing carbon-containing gas and a target material into the plasma torch, cracking the carbon-containing gas to form carbon particles, forming a reduction layer on the surface of the target material by the carbon particles, and forming a target material intermediate material by the reduction layer and the target material. The embodiment of the invention is beneficial to forming the reduction layer on the target material, and the reduction layer has high chemical activity and is convenient for carrying out deoxidation treatment on the target material in the follow-up process.

Description

Intermediate material of target material, forming method thereof and device for realizing forming method

Technical Field

The invention relates to the technical field of semiconductor manufacturing, in particular to a target material intermediate material, a forming method thereof and a device for realizing the forming method.

Background

The sputtering coating belongs to one of the processes for preparing thin films by a physical vapor deposition method, and particularly relates to a method for forming a thin film by bombarding the surface of a target by using high-energy particles so that target atoms or molecules obtain enough energy to escape and deposit on the surface of a base material or a workpiece. Sputter coating has wide application in the fields of semiconductor chip, flat panel display, solar cell manufacturing, and the like.

In the manufacture of semiconductor chips, targets used for sputter coating are ultra-high purity metal materials such as W, mo, ta, and the like, and are used for forming metal wires, diffusion preventing layers, and the like. With the development of semiconductor chips towards high speed, low energy consumption and large capacity of information processing, the requirements of the new generation of semiconductor chip manufacture on the target material are higher and higher. The content of oxygen impurities in the target material not only affects the oxygen content in the sputtered film, but also affects the stability of the sputtering coating process. When the content of oxygen element impurities in the target material is high, abnormal discharge is easy to occur in the sputtering coating process, and large sputtering particles generated by the abnormal discharge easily cause film defects, influence the sputtering coating quality and further cause the yield reduction of semiconductor chips.

The target material is a raw material for manufacturing a target blank, the target blank is processed into a target after a series of processing, and the oxygen content in the target material can directly influence the oxygen content of the formed target.

Therefore, a method for forming a reduction layer on the surface of the target material is needed to reduce the oxygen content on the surface of the target material.

Disclosure of Invention

The invention provides a target material intermediate material, a forming method thereof and a device for realizing the forming method, which are beneficial to forming a reduction layer on the surface of a target material.

In order to solve the above problems, the present invention provides a method for forming an intermediate material for a target, comprising: providing a plasma torch having a plasma therein; and introducing carbon-containing gas and a target material into the plasma torch, cracking the carbon-containing gas to form carbon particles, forming a reduction layer on the surface of the target material by the carbon particles, and forming a target material intermediate material by the reduction layer and the target material.

Optionally, the target raw material is granular inside and outside the plasma torch.

Optionally, the carbon-containing gas comprises methane, acetylene, ethane or propane.

Optionally, the rate of feeding the target raw material into the plasma torch is greater than or equal to 3kg/h.

Optionally, the material of the target raw material includes one or more of W, mo, ta, nb, ru, and Cr.

Optionally, the median particle size of the target raw material is less than 150 μm and greater than 10 μm.

Optionally, the material of the carbon particles includes one or more of nano carbon black, nano graphite, carbon nanotubes, carbon nanofibers, and nano carbon spheres.

Optionally, the carbon particles have a particle size of less than 60nm.

Optionally, the reducing layer is composed of one or more layers of the carbon particles.

Correspondingly, the invention also provides a target intermediate material obtained by the method for forming the target intermediate material, which comprises the following steps: a target material; and the reducing layer is formed on the surface of the target raw material and comprises carbon particles.

Optionally, the material of the reduction layer includes one or more of nano carbon black, nano graphite, carbon nanotubes, carbon nanofibers, and nano carbon spheres.

Correspondingly, the invention also provides a device for realizing the method for forming the intermediate material of the target, which comprises the following steps: the device comprises a plasma torch, wherein a ring-shaped induction coil is embedded in the side wall of the plasma torch, the plasma torch is provided with a gas inlet and a powder feeding port, the gas inlet is suitable for conveying carbon-containing gas, and the powder feeding port is suitable for conveying a target raw material to the plasma torch.

Optionally, the apparatus further comprises: a reactor in communication with the plasma torch bottom, the reactor having a collection port and an exhaust port.

Compared with the prior art, the technical scheme of the embodiment of the invention has the following advantages:

according to the technical scheme of the forming method of the target intermediate material, the plasma is arranged in the plasma torch, the carbon-containing gas and the target raw material are introduced into the plasma torch, the carbon-containing gas is cracked in the plasma atmosphere to form carbon particles, the target raw material floats in the plasma torch, the carbon particles are easy to deposit on the surface of the target raw material, and a large number of carbon particles are adsorbed on the surface of the target raw material to form a reduction layer. The reduction layer has high chemical activity so as to be reacted with oxygen in the target material in the following process.

Furthermore, the target raw material is granular inside and outside the plasma torch, and the target raw material is not melted in the plasma torch, so that a reduction layer is conveniently coated on the surface of the granular target raw material.

According to the technical scheme of the target intermediate material, the target intermediate material comprises a target raw material and a reduction layer, wherein the reduction layer is formed on the surface of the target raw material so as to remove oxygen on the surface of the target raw material in the subsequent process.

Drawings

Fig. 1 is a schematic flow chart of a method for forming an intermediate material of a target according to an embodiment of the present invention;

FIG. 2 is a schematic structural view of a target intermediate formed in accordance with one embodiment of the present invention;

fig. 3 is a schematic structural diagram of an apparatus for forming an intermediate material of a target according to an embodiment of the present invention.

Detailed Description

Embodiments of the present invention form carbon particles by plasma cracking a carbon-containing gas and provide a target raw material into a plasma torch, and a large amount of carbon particles form a reducing layer having high chemical activity on the surface of the target raw material.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Fig. 1 is a schematic flow chart of a method for forming an intermediate material of a target according to an embodiment of the present invention.

Referring to fig. 1, in S11, a plasma torch in which a plasma is formed is provided.

The plasma is formed by ionizing a mixed gas including a basic acting gas and a plasma state control gas. The plasma state control gas is used to control the stability of the plasma and to make the plasma acquire physical properties advantageous for carbon cracking.

In some embodiments, the base action gas is argon; the plasma state control gas is gas with higher ionization energy than argon, such as hydrogen, helium and the like.

The plasma state control gas is mixed in the basic action gas and is introduced into the plasma torch, or the plasma state control gas is introduced into the plasma torch independently.

In one embodiment, the ratio of the volume flow of the argon gas to the volume flow of the hydrogen gas is 10.3 to 10. The volume flow of the argon is 50L/min-300L/min. The volume flow of the hydrogen is 1.5L/min-60L/min.

Preferably, the volume flow ratio of the argon to the hydrogen is 10.6-10, the volume flow ratio of the argon is 80L/min-200L/min, and the volume flow ratio of the hydrogen is 5L/min-30L/min, which helps to ensure sufficient energy density to promote the subsequent carbon cracking reaction, and on the other hand, can prevent carbon particles formed by carbon cracking from growing too fast to cause the particle size of the carbon particles to be too large, thereby ensuring that the carbon particles have good activity.

In one embodiment, the plasma is a thermal plasma, which helps to ensure sufficient energy density to facilitate efficient cracking of carbon in the carbon-containing gas.

And S13, introducing carbon-containing gas and a target material into the plasma torch.

The carbon-containing gas is cracked under the action of the plasma to form carbon particles. And attaching the carbon particles formed by cracking to the surface of the target raw material to form a reduction layer, wherein the target raw material and the reduction layer form a target intermediate material.

In some embodiments, the carbon-containing gas comprises methane. In other embodiments, the carbon-containing gas may also include acetylene, ethane, or propane.

The carbon-containing gas includes, but is not limited to, alkanes such as ethane and propane.

In some embodiments, the methane volumetric flow rate is between 0.2L/min and 20L/min. The methane volume flow directly influences the thickness of the adsorption reduction layer on the surface of the target material.

Preferably, the volume flow of the methane is 0.8L/min-10L/min, on one hand, the carbon cracking reaction rate is improved, the carbon particles are ensured to be uniformly adhered to the surface of the target material, and on the other hand, the energy supply required by the carbon cracking reaction can be ensured to be sufficient.

The carbon particles are nano-sized and in some embodiments, the carbon particles comprise one or more of nano-carbon black, nano-graphite, carbon nanotubes, carbon nanofibers, nano-carbon spheres.

In some embodiments, the carbon particles have a particle size of less than 60nm. The carbon with the nano structure has good activity, and is beneficial to the subsequent reaction with oxygen on the surface of the target material.

In some embodiments, the target feedstock is passed into the plasma torch at a rate of greater than or equal to 3kg/h in order to form a uniform reduced layer on the surface of the target feedstock.

The target material comprises a target material for producing semiconductor chips. The target material comprises one or more of W, mo, ta, nb, ru and Cr.

Generally, the target material will have oxygen impurities, especially in the surface layer. The surface of the target raw material is mainly formed by oxidation reaction with oxygen in the air. Taking the target material as an example of a tantalum material, the outer surface of the raw material of the tantalum target is easily oxidized to form a tantalum oxide layer, so that the raw material of the tantalum target contains oxygen impurities.

The target material is granular inside and outside the plasma torch.

In some embodiments, the median particle size of the target feedstock is less than 150 μm and greater than 10 μm, which is associated with the process of adsorbing carbon particles and affects the ease of process control. Wherein the median particle diameter is the particle diameter of 50% of the cumulative distribution of the target raw material particles. Taking the median particle size of the target raw material as 100 μm as an example, it is shown that, in all the target raw materials, particles larger than 100 μm account for 50%, and particles smaller than 100 μm also account for 50%.

In some embodiments, the process temperature within the plasma torch is below the melting point of the target feedstock. In other embodiments, the process temperature within the plasma torch can be at or above the melting point of the target feedstock. When the process temperature in the plasma torch can be equal to or higher than the melting point of the target raw material, the target raw material is controlled to rapidly pass through the plasma, so that the thermal equilibrium state cannot be reached, the target raw material can be prevented from melting, and a reduction layer is formed on the surface of the granular target raw material.

In some embodiments, the reducing layer is a monolayer of the carbon particles. In other embodiments, the reduction layer is formed by stacking a plurality of layers of the carbon particle phase.

In some embodiments, the target intermediate material is formed such that, assuming that the target raw material contains a first molar amount of oxygen-element impurities, the molar amount of the reduction layer does not exceed 90% to 98% of the first molar amount, so as to reduce the risk of introducing new impurities within the target raw material.

In some embodiments, a carbon-containing gas and a target feedstock are simultaneously introduced into the plasma torch. In other embodiments, a carbon-containing gas is introduced into the plasma torch prior to introducing the target material into the plasma torch.

Referring to fig. 2, an embodiment of the present invention further provides a schematic structural diagram of a target intermediate material 200 obtained by using the target intermediate material forming method. The target intermediate material 200 includes: a target raw material 210; and the reduction layer 220, wherein the reduction layer 220 is formed on the surface of the target raw material 210.

The material of the target material 210 includes one or more of W, mo, ta, nb, ru, and Cr. The target material 210 has an oxygen impurity.

The material of the reduction layer 220 includes a nanocarbon structure.

In some embodiments, the reducing layer 220 is one or more of nano carbon black, nano graphite, carbon nanotube, carbon nanofiber, and nano carbon sphere.

The reduction layer 220 is composed of one or more layers of the carbon particles.

In some embodiments, the target material 210 contains oxygen impurities in a first molar amount, and the molar amount of the reduction layer 220 is not more than 90% to 98% of the first molar amount.

Fig. 3 is a schematic structural diagram of an apparatus 300 for implementing the method for forming the intermediate material of the target according to an embodiment of the present invention.

Referring to fig. 3, the apparatus 300 includes: a plasma torch 310, the plasma torch 310 having a gas inlet 311 and a powder feed port 312, wherein the gas inlet 311 is adapted to deliver a carbon-containing gas; the powder feed port 312 is adapted to be connected to a powder feed container 350 for feeding the target material 210 to the plasma torch 310.

In some embodiments, the gas inlets 311 are adapted to introduce a base action gas, a plasma state control gas, and a carbon-containing gas, respectively.

The number of the gas inlets 311 is plural, and the gas inlets are respectively connected to a first gas cylinder 320, a second gas cylinder 330 and a third gas cylinder 340, wherein the first gas cylinder 320 is suitable for supplying the basic motion gas to the plasma torch 310, the second gas cylinder 330 is suitable for supplying the plasma state control gas to the plasma torch 310, and the third gas cylinder 340 is suitable for supplying the carbon-containing gas to the plasma torch 310.

In some embodiments, a ring-shaped induction coil 313 is embedded in the side wall of the plasma torch 310, and the ring-shaped induction coil 313 is suitable for generating a high-frequency induction electromagnetic field to excite the mixed gas formed by the basic action gas and the plasma state control gas to be ionized, so that stable plasma is formed.

In some embodiments, the apparatus 300 further comprises: a reactor 360, the reactor 360 being in communication with the bottom of the plasma torch 310, the reactor 360 having a collection port 314 and an exhaust port 315.

In some embodiments, the bottom of the reaction chamber 310 has a collection port 314, and the collection port 314 is adapted to collect the formed target material 200.

The exhaust port 315 is adapted to exhaust excess carbon-containing gas, the base action gas, or the plasma state control gas.

The carbon-containing gas is cracked within the plasma torch 310 to form carbon particles 221. In the reactor 360, the carbon particles 221 uniformly coat the surface of the target raw material 210 to form a reduction layer 220 (refer to fig. 2), and the target raw material 210 and the reduction layer 220 constitute the target intermediate material 200.

In other embodiments, not only does carbon particles 221 deposit on the surface of the target feedstock 210 in the reactor 360, but the carbon particles 221 begin to deposit on the surface of the target feedstock 210 in the plasma torch 310.

As a specific embodiment of the present invention, the following specific process for forming a reduction layer on the surface of a tantalum target material, taking tantalum as an example, includes: and in the process of forming the plasma, the volume flow of the argon is 80L/min-200L/min. The volume flow of the hydrogen is 6L/min-20L/min.

In the process of introducing the carbon-containing gas, the carbon-containing gas comprises methane, and the volume flow rate of the methane is 0.9L/min-8L/min.

And cracking the carbon-containing gas in a plasma atmosphere to form carbon particles, wherein the particle size of the carbon particles is less than 55nm.

And in the process of conveying the tantalum target raw material into the plasma torch, the speed of the tantalum target raw material is 4 kg/h-25 kg/h.

Preferably, the speed of the raw material of the tantalum target is 6 kg/h-10 kg/h.

The median particle size of the tantalum target raw material is less than 62 μm and more than 15 μm.

The reduction layer adsorbed and formed on the surface of the tantalum target raw material is formed by a single layer of carbon particles.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for forming a target intermediate material is characterized by comprising the following steps:

providing a plasma torch having a plasma therein;

introducing carbon-containing gas and a target raw material into the plasma torch, cracking the carbon-containing gas to form carbon particles, forming a reduction layer on the surface of the target raw material by the carbon particles, wherein the reduction layer is formed by one or more layers of the carbon particles, the reduction layer and the target raw material form a target intermediate material, and the parameters of reaction conditions comprise: the volume flow ratio of argon to hydrogen is (10); the volume flow of the argon is 50L/min-300L/min; the volume flow of the hydrogen is 1.5L/min-60L/min, and the carbon-containing gas comprises: methane, wherein the volume flow of the methane is 0.2L/min-20L/min.

2. The method of forming a target intermediate according to claim 1, wherein the target raw material is in the form of pellets both inside and outside the plasma torch.

3. The method of claim 1, wherein the rate of the target feedstock passing into the plasma torch is greater than or equal to 3kg/h.

4. The method of claim 1, wherein the target material comprises one or more of W, mo, ta, nb, ru, and Cr.

5. The method of claim 1, wherein the target feedstock has a median particle size of less than 150 μm and greater than 10 μm.

6. The method of claim 1, wherein the carbon particles are formed from a material selected from the group consisting of carbon blacks, graphites, nanotubes, nanofibers and spheres.

7. The method of forming a target intermediate material according to claim 1, wherein the carbon particles have a particle size of less than 60nm.

8. A target material intermediate obtained by the method for forming a target material intermediate according to any one of claims 1 to 7, comprising:

a target material;

and the reducing layer is formed on the surface of the target raw material and is composed of one or more layers of carbon particles.

9. The target intermediate material according to claim 8, wherein the material of the target raw material comprises one or more of W, mo, ta, nb, ru, cr.

10. The target material intermediate of claim 8, wherein the material of the reduction layer comprises one or more of nano carbon black, nano graphite, carbon nanotubes, carbon nanofibers, nano carbon spheres.