TW201309825A - Target material to form stannous oxide - Google Patents

Abstract

Disclosed is a target material to form stannous oxide. The composition of this target material includes tin dioxide (SnO2) and tin (Sn). Utilizing the traditional sputtering process and in combination with a Post-Annealing process, stannous oxide material can be obtained. This mixed target material having tin dioxide and tin which is evenly distributed and a compact structure which can be sintered at high temperature, overcomes the traditional shortcomings of a loosened structure in the stannous oxide target material and the inability to sinter at high-temperature. In addition this target material is more suitable for the application in the sputtering process of mass production.

Description

A target capable of forming stannous oxide

The invention relates to a physical vapor deposition target, in particular to a combination of the components of the target and a general process, which can successfully prepare a material containing stannous oxide.

After the advent of the transparent oxide thin film transistor theory, it immediately attracted the attention of many researchers and expanded the research and development of oxide thin film transistors. At present, the characteristics of oxide thin film transistor components have surpassed that of amorphous germanium and organic semiconductors, and even approached polycrystalline germanium. , showing the potential of practical applications. Oxide semiconductor thin film transistors can attract a wide range of attention, the most important of which is their special electronic structure and carrier transport characteristics.

In recent years, the liquid crystal display industry has flourished, and among them, amorphous silicon TFT (a-Si TFT) plays an important role. However, the mobility of amorphous germanium is quite limited, and there are still many limitations in panel design and application. At present, oxide semiconductor thin film transistors, carrier mobility and stability can be much higher than amorphous germanium, and even approach polycrystalline germanium.

Another Organic Light-Emitting Diodes (OLED) and display technology has been regarded as an important next generation display technology in recent years. However, the lack of proper driving thin film transistor backplane technology has always been one of the main factors that the active matrix organic light emitting diode (AMOLED) can not be effectively mass-produced; the amorphous germanium thin film transistor commonly used in liquid crystal displays (amorphous Si TFT, a-Si TFT), because of its low carrier mobility (<1cm ² /Vs), low reliability under current operation, not suitable for organic light-emitting diodes driving active matrix; Low-temperature polycrystalline silicon TFT (p-Si TFT) is used to drive the organic light-emitting diode, which may cause unevenness of component characteristics due to its polycrystalline structure and process, and further cause uneven display of pixels. Problems such as image quality, and the process of polycrystalline germanium thin film transistors are more complicated than those of amorphous germanium thin film transistors, and thus there is a problem of high cost and mass production which is difficult to enlarge to a large size panel.

Oxide semiconductor thin film transistors have become an important soft transistor technology option due to their low temperature process characteristics and better electrical properties than amorphous germanium thin film transistors and organic thin film transistors.

At present, the oxide semiconductor thin film transistor has been mainly n-type, and the P-type oxide semiconductor thin film transistor has a relatively high degree of difficulty, and there are few related research reports. However, in the practical application of thin film transistors, the development of P-type oxide semiconductor thin film transistors is critical for the application of the driver backplane technology or the formation of integrated/integrated circuits.

Due to the difficulty in fabricating P-type oxide semiconductors, the main hole mobility of materials is low. In the general oxide system, the 02p orbital domain tends to form a deep localized valence band maximum (VBM), the hole is hopping conduction and the mobility is low. In order to improve the mobility of holes in oxide semiconductors, one strategy is to find oxide semiconductors with VBMs mixed with O 2p orbital domains and metal-s-rail domains (or pseudo-closed s orbital domains), which are delocalized by metal s orbital domains. Improve hole conduction characteristics. Stannous oxide is found to have P-type semiconductor properties due to its stable metal ns ² electronic configuration that can be mixed with the O 2p orbital domain. In addition, stannous oxide has the advantages of non-toxicity, simple composition, low cost, and the like, and has the potential to develop mature p-type oxide semiconductor components.

According to the conventional literature, the preparation of stannous oxide requires the use of a stannous oxide target for sputtering and a post-annealing process. However, the stannous oxide material is unstable at temperatures above 270 ° C and deteriorates, so it is not suitable for high temperature sintering. If the stannous oxide target is not sintered at a high temperature (for example, 500 ° C), the target structure is loose, which may cause problems such as poor process stability and powder contamination. For example, as shown in Fig. 1, it shows a conventional stannous oxide target, the target material is stannous oxide powder, and the target powder is sintered under a argon atmosphere using a low temperature hot pressing method (about 250 ° C). It has a diameter of 3 inches, a thickness of 3 mm, and a copper (Cu) back plate of 3 mm on the back. It can be seen from the illustration that the target sintering is not complete, the surface of the target is still powdery and the powder is easy to fall off.

Please refer to Fig. 2, which shows the composition and results of a conventional stannous oxide target analyzed by an X-ray diffraction analyzer. Although the stannous oxide target is simple in composition, the rigidity is insufficient (relative density about 61.4%) cannot withstand long-term, high-power sputtering processes and is prone to damage; the loose target structure also causes the plating rate during the sputtering process. The drift of the process conditions makes the process stability worse. Finally, the powder on the surface of the target will contaminate the vacuum system and the sample, causing the particle issue to reduce the process yield. The aluminum (Al) signal comes from X-ray. The container itself is measured by the diffraction analyzer.

For this reason, the applicant has been able to withstand the high-temperature sintering, mass-produced tin oxide/tin mixed component target in view of the lack of the prior art, and the tin oxide film can be obtained by using a conventional conventional process. Invented in the present case "a target for the formation of stannous oxide" to improve the lack of the above-mentioned conventional means.

It is an object of the present invention to provide a target which can produce stannous oxide. The target component contains tin oxide and tin, and can be sintered at a high temperature (for example, 500 ° C). After sintering, the composition is uniform and the structure is dense (for example, relative density > 80%). A stannous oxide film can be obtained using a conventional sputtering process and a sputtering gas (for example, argon) in combination with a post-annealing process. The tin oxide/tin mixed component target can overcome the shortcomings of the preparation and process of the stannous oxide target, and can be applied to the mass production sputtering process.

In order to achieve the above object, the present invention provides a target for forming stannous oxide, the target component comprising: tin oxide and tin, wherein the ratio of tin to tin oxide is between 1.5 and 0.098, and The target material is obtained by a physical vapor deposition and a post-annealing process to obtain a stannous oxide material.

According to the above concept, wherein the target can be subjected to a high temperature sintering process, and the sintering temperature can be above 270 °C.

According to the above concept, the stannous oxide material can be applied to an oxide thin film transistor.

Therefore, the performance of the present invention not only effectively provides a target for preparing stannous oxide, but also can withstand a high-temperature sintering environment (for example, 500 ° C), and the target composition after sintering is uniform and high in density, combined with physical vapor deposition and post-annealing. The process of Post-Annealing can obtain a film of stannous oxide. The target of tin oxide/tin mixed component can overcome the shortcomings of preparation and process of stannous oxide target, and can be applied to mass production process. It is not only simple in composition, low in cost, but also can be developed. Mature P-type oxide semiconductor components meet industrial needs.

The present invention will be fully understood from the following description of the embodiments, and the skilled person in the art can be practiced by the present invention. However, the implementation of the present invention is not limited by the following embodiments.

Referring to Figure 3, there is shown a tin oxide/tin mixed target of the present invention. The mixed target is prepared by placing a stannous oxide powder or a tin/tin oxide powder into a molding frame. In the present embodiment, a stannous oxide powder is used, and then the molding frame is placed in an argon-filled environment and formed. A high temperature (500 ° C) is applied around the frame for powder sintering while applying pressure on the forming frame. After a certain period of time, the temperature is lowered to form a dense target (the relative density of which is greater than 80%) as shown.

Please refer to Fig. 4: which shows the composition and results of the tin oxide/tin mixed target of the present invention analyzed by an X-ray diffraction analyzer. The vertical axis represents the intensity, and the horizontal axis represents the diffraction angle. It can be seen from the figure that the tin oxide/tin mixed target has no stannous oxide component, and the tin and tin oxide signals are distributed at the respective crystal phase angles.

Please refer to Fig. 5 for the results of analyzing the stannous oxide film deposited by the tin oxide/tin mixed target of the present invention by an X-ray diffraction analyzer. Wherein, the vertical axis represents the intensity, and the horizontal axis represents the X-ray diffraction angle. In this embodiment, argon gas is used as the sputtering gas, the process power of the embodiment is 200 W, the process gas pressure is adjusted to 30 mTorr, and the sample is subjected to a vacuum of 500 ° C. The post annealing process is one hour. From the analysis of Fig. 5, it was found that a tin oxide/tin mixed target can be used to form a film mainly composed of stannous oxide crystal.

The results of the stannous oxide film deposited by the tin oxide/tin mixed target of the present invention were analyzed by a Hall effect meter. It was found by Hall measurement that it has P-type semiconductor characteristics, and its resistivity is about 22.7 Ω-cm, the hole mobility is about 0.42 cm ² /Vs, and the carrier concentration is about 6.5× ^{10 17} cm ^-3 .

In summary, the present invention proposes that a target material containing no stannous oxide component can be plated with a film material containing stannous oxide. Therefore, it is only necessary to use a suitable proportion of a mixed target of tin and tin oxide. The sputtering process and the post-annealing process can obtain a film material containing stannous oxide, and the stannous oxide film material can be applied to the fabrication of a P-type oxide semiconductor thin film transistor, contributing to the oxide thin film transistor. In the long-term development, in the panel industry and oxide film and transistor related industries, it meets the market demand and has a promising business application.

The above-described embodiments are merely illustrative of the principles of the preferred embodiments of the invention and their advantages, and are not intended to limit the invention. Therefore, those skilled in the art can make modifications and changes to the embodiments described above without departing from the spirit and scope of the invention.

Figure 1: shows a conventional stannous oxide target.

Figure 2: shows the composition and results of a conventional stannous oxide target analyzed by an X-ray diffraction analyzer.

Figure 3: shows a tin oxide/tin mixed target of the present invention.

Figure 4: shows the composition and results of the tin oxide/tin mixed target of the present invention analyzed by an X-ray diffraction analyzer.

Figure 5: shows the results of analysis of the stannous oxide film deposited by the tin oxide/tin mixed target of the present invention by an X-ray diffraction analyzer.

Claims (3)

A target for forming stannous oxide, the target component comprising: tin oxide (SnO ₂ ) and tin (Sn), wherein the ratio of tin to tin oxide is between 1.5 and 0.098, and the target A stannous oxide (SnO) material can be obtained via physical vapor deposition and post-annealing processes. The target of claim 1, wherein the target is subjected to a high temperature sintering process and the sintering temperature is up to 270 ° C or higher. The target of claim 1, wherein the stannous oxide material is applicable to an oxide thin film transistor.