Introduction of news, developments and applications of different type of sputtering target materials
Application of sputtering targets
The very important consumption of mordern semicon industry
The development trend of target material technology is closely related to the film technology development trend of downstream application industry. With the technical improvement of film products or components in application industry, target technology should also change accordingly. For example, IC manufacturers have been devoting themselves to the development of low resistivity copper wiring in recent years, and it is expected that the original aluminum film will be replaced greatly in the next few years, so the development of copper target and its barrier target materials will be urgent. In addition, in recent years, flat panel display (FPD) has greatly replaced the CRT based computer display and television market, which will greatly increase the technology and market demand of ITO targets. In addition, in terms of storage technology. The demand for high-density, high-capacity hard disk and high-density erasable CD-ROM continues to increase, which leads to changes in the demand for target materials in the application industry. Next, we will introduce the main application fields of targets and the development trend of targets in these fields.
Microelectronics
In all application industries, the semiconductor industry has the most stringent quality requirements for target sputtering films. Today, 12 inch (300 port) silicon wafers have been made, but the width of the interconnects is decreasing. Silicon wafer manufacturers require large size, high purity, low segregation and fine grains, which requires better microstructure of the target. The crystal size and uniformity of the target have been considered to be the key factors affecting the deposition rate of the films. In addition, the purity of the film is closely related to the purity of the target. In the past, 99.995% (4n5) purity copper target may be able to meet the needs of semiconductor manufacturers for 0.35pm process, but it can not meet the current process requirements of 0.25um. However, for the 0.18um} process or even 0.13M process, the purity of the target material required will reach 5 or even 6N. Compared with aluminum, copper has higher resistance to electromigration and lower resistivity, which can meet the requirements! However, there are other problems: the adhesion strength between copper and organic dielectric materials is low, and it is easy to react, which leads to the corrosion and open circuit of copper interconnects in the process of use. In order to solve these problems, a barrier layer should be set between copper and dielectric layer. The barrier material is usually made of metals and their compounds with high melting point and high resistivity. Therefore, the thickness of the barrier layer should be less than 50nm, and it should have good adhesion with copper and dielectric materials. The barrier materials of copper interconnection and aluminum interconnection are different, so new target materials need to be developed. The target materials for copper interconnection barrier layer include TA, W, TASI, WSI, etc. However, Ta and W are refractory metals. It is relatively difficult to make them. Now, we are studying the substitute materials of molybdenum and chromium.
Display
In recent years, flat panel display (FPD) has greatly impacted the market of CRT based computer displays and TV sets, which will also drive the technology and market demand of ITO targets. Nowadays, there are two kinds of ITO targets. One is sintering with nano indium oxide and tin oxide powder, and the other is using indium tin alloy target. Indium tin alloy target can be prepared by DC reactive sputtering, but the target surface will be oxidized, which will affect the sputtering rate, and it is not easy to obtain large-scale Taiwan gold target. Nowadays, the first method is usually used to produce ITO target, and l} IRF reactive sputtering coating is used. It has the advantages of fast deposition speed, accurate control of film thickness, high conductivity, good consistency of film and strong adhesion with substrate. However, it is difficult to fabricate the target because indium oxide and tin oxide are not easy to be sintered together. Generally, ZrO2, Bi2O3 and CEO are used as sintering additives, and the target materials with density of 93% ~ 98% of the theoretical value can be obtained. The properties of ITO films formed in this way have a great relationship with the additives. The Japanese scientists used bizo as additive. Bi2O3 was melted at 820cr, and the excess part of Bi2O3 was volatilized at 1500 ℃. In this way, pure ITO target could be obtained by liquid phase sintering. Moreover, the oxide materials needed are not necessarily nanoparticles, which can simplify the previous process. The resistivity of ITO thin films obtained from such target materials as Sichuan is 8.1 × 10n-cm, which is close to the resistivity of pure ITO films. The size of FPD and conductive glass are quite fire, and the width of conductive glass can reach 3133_ In order to improve the utilization of the target, ITO targets with different shapes, such as cylindrical, were developed. In 2000, the National Development Planning Commission and the Ministry of science and technology of the people's Republic of China included ITO large-scale targets in the "guide to key areas of information industry priority development at present".
Storage chip
In terms of storage technology, the development of high-density and high-capacity hard disk requires a large number of giant magnetoresistance (GMR) films. COF ~ Cu multilayer composite films are widely used nowadays. TbFeCo alloy target material for magneto-optical disk is still in further development. The magneto-optical disk made of it has the characteristics of large storage capacity, long service life and repeated non-contact erasure. Nowadays, magneto-optical disks have TbFeCo / Ta and TbFeCo / Al layer composite film structures. The Kerr rotation angle of TbFeCo / AI structure is 58, while that of tbfecoffa is close to 0.8. It is found that the target with low permeability has high AC partial discharge voltage and dielectric strength.
Phase change memory (PCM) based on germanium antimony telluride shows significant commercial potential and is an alternative memory technology for NOR flash memory and some DRAM markets. However, one of the challenges in achieving faster scaling down is the lack of fully enclosed cells that can further reduce the reset current. Reducing reset current can reduce the power consumption of memory, prolong battery life and improve data bandwidth, which is a very important feature for current data centric, highly portable consumer devices.
Microelectronics
In all application industries, the semiconductor industry has the most stringent quality requirements for target sputtering films. Today, 12 inch (300 port) silicon wafers have been made, but the width of the interconnects is decreasing. Silicon wafer manufacturers require large size, high purity, low segregation and fine grains, which requires better microstructure of the target. The crystal size and uniformity of the target have been considered to be the key factors affecting the deposition rate of the films. In addition, the purity of the film is closely related to the purity of the target. In the past, 99.995% (4n5) purity copper target may be able to meet the needs of semiconductor manufacturers for 0.35pm process, but it can not meet the current process requirements of 0.25um. However, for the 0.18um} process or even 0.13M process, the purity of the target material required will reach 5 or even 6N. Compared with aluminum, copper has higher resistance to electromigration and lower resistivity, which can meet the requirements! However, there are other problems: the adhesion strength between copper and organic dielectric materials is low, and it is easy to react, which leads to the corrosion and open circuit of copper interconnects in the process of use. In order to solve these problems, a barrier layer should be set between copper and dielectric layer. The barrier material is usually made of metals and their compounds with high melting point and high resistivity. Therefore, the thickness of the barrier layer should be less than 50nm, and it should have good adhesion with copper and dielectric materials. The barrier materials of copper interconnection and aluminum interconnection are different, so new target materials need to be developed. The target materials for copper interconnection barrier layer include TA, W, TASI, WSI, etc. However, Ta and W are refractory metals. It is relatively difficult to make them. Now, we are studying the substitute materials of molybdenum and chromium.
Display
In recent years, flat panel display (FPD) has greatly impacted the market of CRT based computer displays and TV sets, which will also drive the technology and market demand of ITO targets. Nowadays, there are two kinds of ITO targets. One is sintering with nano indium oxide and tin oxide powder, and the other is using indium tin alloy target. Indium tin alloy target can be prepared by DC reactive sputtering, but the target surface will be oxidized, which will affect the sputtering rate, and it is not easy to obtain large-scale Taiwan gold target. Nowadays, the first method is usually used to produce ITO target, and l} IRF reactive sputtering coating is used. It has the advantages of fast deposition speed, accurate control of film thickness, high conductivity, good consistency of film and strong adhesion with substrate. However, it is difficult to fabricate the target because indium oxide and tin oxide are not easy to be sintered together. Generally, ZrO2, Bi2O3 and CEO are used as sintering additives, and the target materials with density of 93% ~ 98% of the theoretical value can be obtained. The properties of ITO films formed in this way have a great relationship with the additives. The Japanese scientists used bizo as additive. Bi2O3 was melted at 820cr, and the excess part of Bi2O3 was volatilized at 1500 ℃. In this way, pure ITO target could be obtained by liquid phase sintering. Moreover, the oxide materials needed are not necessarily nanoparticles, which can simplify the previous process. The resistivity of ITO thin films obtained from such target materials as Sichuan is 8.1 × 10n-cm, which is close to the resistivity of pure ITO films. The size of FPD and conductive glass are quite fire, and the width of conductive glass can reach 3133_ In order to improve the utilization of the target, ITO targets with different shapes, such as cylindrical, were developed. In 2000, the National Development Planning Commission and the Ministry of science and technology of the people's Republic of China included ITO large-scale targets in the "guide to key areas of information industry priority development at present".
Storage chip
In terms of storage technology, the development of high-density and high-capacity hard disk requires a large number of giant magnetoresistance (GMR) films. COF ~ Cu multilayer composite films are widely used nowadays. TbFeCo alloy target material for magneto-optical disk is still in further development. The magneto-optical disk made of it has the characteristics of large storage capacity, long service life and repeated non-contact erasure. Nowadays, magneto-optical disks have TbFeCo / Ta and TbFeCo / Al layer composite film structures. The Kerr rotation angle of TbFeCo / AI structure is 58, while that of tbfecoffa is close to 0.8. It is found that the target with low permeability has high AC partial discharge voltage and dielectric strength.
Phase change memory (PCM) based on germanium antimony telluride shows significant commercial potential and is an alternative memory technology for NOR flash memory and some DRAM markets. However, one of the challenges in achieving faster scaling down is the lack of fully enclosed cells that can further reduce the reset current. Reducing reset current can reduce the power consumption of memory, prolong battery life and improve data bandwidth, which is a very important feature for current data centric, highly portable consumer devices.
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Photo supported by QS Advanced Materials Inc
