Magnetron sputtering target material and manufacturing method thereof

Abstract

The invention discloses a magnetron sputtering target material and a manufacturing method thereof. The magnetron sputtering target material comprises 0-49 at% of Ni, 1-30 at% of Ti, 1-5 at% of W and the balance Mo and inevitable impurities. According to the present invention, a high-density and high-purity Mo alloy sputtering target can be stably produced at low cost, and a wiring thin film having low resistance, excellent heat resistance, moisture resistance, oxidation resistance, and excellent diffusion resistance can be provided.

Description

Technical Field

[0001] The present invention relates to the technical field of wiring film materials, and in particular to a magnetron sputtering target material and a manufacturing method thereof. Background Art

[0002] In flat panel displays (FPDs), low-resistance wiring films are required. In recent years, with the large screen and fast response requirements of FPDs, low resistance of wiring films is particularly important. When the main wiring material Al or Cu is in direct contact with glass or Si, the performance of the thin film transistor (TFT) is reduced due to heat diffusion caused by the heating process in the FPD process. Usually, a diffusion barrier film composed of Mo or Mo alloy is formed between Al or Cu and the substrate. In addition, Al or Cu has poor adhesion on glass or Si wafers. In order to ensure tightness, Mo or Mo alloy is also needed as a wiring film between Al or Cu and the substrate.

[0003] On the other hand, when manufacturing FPD, the wiring film on the substrate is formed and left in the atmosphere for a long time. At the same time, in FPD using flexible organic materials as the substrate, the resin film has high moisture permeability and is prone to release moisture after being left for a long time. The current metal films of Mo, Mo-Nb and Mo-Ti alloys have insufficient moisture resistance and oxidation resistance, causing the Cu metal film to discolor and increase resistance.

[0004] In recent years, the use of oxide semiconductors such as IGZO has been increasing year by year to meet the requirements of high-speed response and low power for long-term use. Oxide semiconductors require high-temperature processing after film formation, and the wiring layer also requires higher heat resistance and diffusion resistance.

[0005] As a method of forming such a wiring film, the most suitable method is magnetron sputtering. Compared with other physical vapor deposition (PVD) methods, magnetron sputtering can more stably form a large-area uniform thickness film with high composition consistency. In order to obtain a wiring film by magnetron sputtering, a corresponding magnetron sputtering target is required.

[0006] The Mo-Ti-Ni alloy wiring film proposed in patent documents CN103990802A and CN102956158A has better heat resistance, moisture resistance and oxidation resistance. However, in the Mo-Ti-Ni wiring film, a relatively high content of Ti and Ni is added. Among them, Ni has a strong diffusion ability at high temperature compared to Mo, and a higher Ni element content leads to a decrease in the wiring film's ability to resist diffusion of Cu; at the same time, the addition of Ti reduces the heat resistance of the overall film. In the FPD manufacturing process, the diffusion resistance performance is relative to pure Mo and a Mo alloy with a small amount of alloying elements added. In addition, the Ni added to the MoTiNi film is generally easy to alloy with the copper of the main wiring, resulting in an increase in the resistance value of the main wiring. In addition, Ti also has the problem of high-temperature diffusion phenomenon causing the main line resistance value to increase, and easy oxidation when heated by the atmosphere.

[0007] Patent document CN107039097B proposes to use MoW instead of pure Mo as a gate electrode to reduce the abnormal coefficient; the W-containing covering layer can improve the heat resistance.

[0008] The quaternary alloy film containing Mo, W, Ti, and Ni has good oxidation resistance, moisture resistance, and heat resistance. However, the performance of the quaternary alloy wiring film is directly related to the uniformity of the quaternary target material itself. In particular, when the added W element is unevenly distributed, the film resistance will increase and the etching performance will be greatly reduced. Summary of the invention

[0009] The main purpose of the present invention is to provide a magnetron sputtering target material, which can effectively solve the problems in the background technology.

[0010] To achieve the above object, the technical solution adopted by the present invention is: A magnetron sputtering target material comprises 0-49at% of Ni, 1-30at% of Ti, 1-5at% of W, and the remainder is Mo and unavoidable impurities.

[0011] A method for manufacturing a magnetron sputtering target comprises the following steps: firstly preparing MoW alloy powder, then mixing MoW with single substance or alloy powder containing Ni and Ti, and then performing pressure sintering. After the pressure sintering, the added element Ni as a magnetic material is alloyed by heat treatment in vacuum or inert atmosphere to perform non-magneticization.

[0012] Preferably, the MoW alloy is prepared by a co-reduction method, wherein ammonium paratungstate and ammonium molybdate solutions are mixed, evaporated and crystallized, and then calcined and reduced to obtain highly alloyed MoW alloy powder.

[0013] Preferably, the Ni alloy powder is Ni-Ti, Ni-Mo or Ni-Mo-Ti alloy powder.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention can stably and inexpensively manufacture high-density, high-purity Mo alloy sputtering targets, and can provide Mo alloy sputtering targets for wiring thin films with low resistance, excellent heat resistance, moisture resistance, oxidation resistance, and excellent diffusion resistance. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0016] This embodiment provides a magnetron sputtering target, including 0-49at% Ni, 1-30at% Ti, 1-5at% W, and the remainder is Mo and unavoidable impurities.

[0017] The manufacturing method is to first prepare MoW alloy powder, then mix MoW with single substance or alloy powder containing Ni and Ti, and then perform pressure sintering. After pressure sintering, the added element Ni as a magnetic material is alloyed by heat treatment in vacuum or inert atmosphere to make it non-magnetic.

[0018] Specifically, firstly, the alloying method of Mo and W preferably adopts the co-reduction method, that is, in the liquid phase, ammonium paratungstate and ammonium molybdate solution are mixed and evaporated and crystallized, and then calcined and reduced to obtain highly alloyed MoW alloy powder.

[0019] In addition, Ni alloy powder can use Ni-Ti, Ni-Mo or Ni-Mo-Ti alloy powder. The preparation methods of these powders include but are not limited to atomization method, rotary anode method and oxide co-reduction method.

[0020] Pressurization uses commonly used methods in the industry, including but not limited to dry pressing or cold isostatic pressing (CIP). The pressure is 20-200MPa. If the pressure is less than 20MPa, it is difficult to form; if the pressure is higher than 200MPa, the equipment cost is high and the pressed green sheet is prone to cracks.

[0021] Pressure sintering can use hot isostatic pressing (HIP) and hot pressing (HP) methods. The sintering temperature is preferably carried out under the conditions of 800-1500°C, 20-200MPa, and 1-10 hours. When the sintering temperature is less than 800°C, it is difficult to obtain a high-density sintered blank; when the sintering temperature is higher than 1500°C, abnormal grain growth is likely to occur, and it is difficult to obtain a uniform and fine structure. When the pressure is less than 20MPa, it is difficult to obtain a high-density sintered body; when the pressure is greater than 200MPa, the equipment cost is too high. When the sintering time is less than 1 hour, it is difficult to sinter fully; when the sintering time is greater than 10 hours, the manufacturing cost is too high. In addition, the hot isostatic pressing or hot pressing method adopts a process widely used in the industry.

[0022] In the Mo alloy sputtering target of the present invention, Ni serves to improve the oxidation resistance of the wiring film, Ti serves to improve the moisture resistance of the wiring film, and W serves to improve the diffusion resistance performance of the wiring film.

[0023] When the Ni addition amount is less than 10at%, the oxidation resistance is insufficient; when the Ni content is higher than 49at%, Ni easily diffuses into Cu and increases the resistance.

[0024] When the Ti content is less than 1 at %, the moisture resistance is not sufficiently improved; when the Ti content is higher than 30 at %, the etching performance is degraded.

[0025] When the W content is less than 1 at%, the diffusion resistance is insufficiently improved; when the W content is higher than 5 at%, the etching performance of the film decreases.

[0026] In addition, the content of other elements other than the main component of the Mo alloy target in the present invention should be as small as possible. The increase of impurity components may increase the film resistance on the one hand, and on the other hand, may deteriorate the crystallinity of the film, and adversely affect the moisture resistance, oxidation resistance and diffusion resistance.

[0027] The following are examples from actual production processes: The atomic ratio of production is: Mo-15%Ni-15%Ti-1%W, and the rest is inevitable impurities. First, a Mo-30%W alloy powder with a purity of 99.98% and an average particle size of 4μm is obtained by a co-reduction method; a Mo-50%Ni alloy powder with a purity of 99.98% and an average particle size of 6μm is obtained by a co-reduction method; a Ti powder with a purity of 99.95% and an average particle size of 15μm is obtained. After weighing various powders according to the above atomic ratio, they are mixed using a drum ball mill to obtain a mixed powder. After that, the mixed powder is formed by cold isostatic pressing at 160MPa to obtain an ingot. After that, it is filled into a container made of carbon steel, heated at 400℃ for 6 hours for degassing, and then sealed. Use HIP to sinter at 1200℃ and 145MPa for 4 hours. After cooling, remove it to obtain a Mo alloy ingot.

[0028] The relative density of the obtained alloy ingot was measured by the Archimedean drainage method and was found to be 99.93%, confirming that a high-density sputtering target was obtained.

[0029] The Mo alloy ingot was cut into a sputtering target with a diameter of 100 mm and a thickness of 3 mm. Sputtering was performed under an Ar atmosphere pressure of 0.5 Pa, a power of 500 W, and a substrate temperature of 200°C to obtain a Mo alloy film with a thickness of 30 nm. A Cu film with a thickness of 300 nm was then sputtered in the same manner, and finally a Mo alloy film with a thickness of 30 nm was sputtered. After forming a three-layer structure, its moisture resistance, oxidation resistance, and diffusion resistance were evaluated.

[0030] The three-layer structure film was placed in an environment of temperature 85°C and humidity 85% for 72 hours, and visual observation confirmed that the film had no discoloration and had high moisture resistance.

[0031] The three-layer structure film was heated at 350° C. in air for 30 minutes, and visual observation confirmed that the film had no discoloration, indicating high oxidation resistance.

[0032] Comparing the changes in square resistance of the above-mentioned films before and after being placed in an environment of 85°C and 85% humidity, and before and after being heated in an atmospheric environment of 350°C, the total square resistance change is ≤10%, indicating that the film has excellent diffusion resistance.

[0033] In addition, sputtering targets of pure Mo, MoTi, MoNi, and MoTiNi alloy were also prepared as comparison using a similar method.

[0034] As an evaluation of moisture resistance, the reflectance change after leaving the film in a high temperature and high humidity atmosphere of 85° C.×85% for 100 hours, 200 hours, and 300 hours was measured.

[0035] As an evaluation of oxidation resistance, changes in reflectance after heating at 400° C. in the atmosphere for 1 hour, 2 hours, and 3 hours were measured.

[0036] As an evaluation of diffusion resistance, changes in the sheet resistance of the film after heating at 400° C. in a vacuum for 1 hour, 2 hours, and 3 hours were measured.

[0037] The moisture resistance test results are shown in the following table:

[0038] The oxidation resistance test results are shown in the following table:

[0039] The group diffusion test results are shown below:

[0040] As far as the results of the present invention are concerned, it can be confirmed that by adding a small amount of W to Mo-Ti-Ni, the diffusion resistance of the film can be effectively improved, so that the film has the properties of high temperature resistance, moisture resistance and diffusion resistance.

[0041] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which shall fall within the scope of the present invention to be protected. The scope of protection of the present invention shall be determined by the attached claims and their equivalents.

Claims

1. A magnetron sputtering target, characterized in that: It comprises 0-49at% Ni, 1-30at% Ti, 1-5at% W, and the balance is Mo and unavoidable impurities.

2. A method for manufacturing a magnetron sputtering target, characterized in that: First, MoW alloy powder is prepared, and then MoW is mixed with a single substance or alloy powder containing Ni and Ti, and then pressure sintering is performed. After pressure sintering, Ni, an added element of the magnetic material, is alloyed by heat treatment in a vacuum or inert atmosphere to make it non-magnetic.

3. The method for manufacturing a magnetron sputtering target according to claim 2, characterized in that: The MoW alloy is made by a co-reduction method, in which ammonium paratungstate and ammonium molybdate solutions are mixed, evaporated and crystallized, and then calcined and reduced to obtain highly alloyed MoW alloy powder.

4. The method for manufacturing a magnetron sputtering target according to claim 3, characterized in that: The Ni alloy powder is one of Ni-Ti, Ni-Mo or Ni-Mo-Ti alloy powder.

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