Silicon Wafer: 4 Types of Wet Cleaning Method

After the silicon wafer is processed by different processes such as slicing, chamfering, grinding, surface treatment, polishing, and epitaxy, the surface has been seriously stained. The purpose of cleaning the Si wafer is to remove particles, metal ions and organic substances on the surface of the silicon wafer.

Semiconductor-Silicon-Wafers

Wet cleaning uses chemical solvents with strong corrosive and oxidizing properties, such as H2SO4, H2O2, DHF, NH3•H2O, etc. The impurity particles on the surface of the silicon wafer react with the solvent to form soluble substances and gases. In order to improve the cleaning effect, it is possible to use mega-acoustic, heating, vacuum and other technical means, and finally use ultra-pure water to clean the surface of the silicon wafer to obtain a silicon wafer that meets the cleanliness requirements.

There are several methods for wet cleaning the silicon semiconductor wafer:

RCA Cleaning for Silicon Wafer

Kern et al. proposed the RCA cleaning method in 1965. According to the SPM, DHF, SC-1, and SC-2 sequences, the RCA cleaning method basically satisfies the requirements of most wafer cleanliness. Cleaning the silicon wafers by this method not only improves the cleaning efficiency, reduces the cost, saves time, obtains excellent surface cleanliness, but also improves the electrochemical performance of the Si wafer.

Ultrasonic Cleaning for Silicon Wafer

Ultrasonic cleaning is a cleaning method widely used in the semiconductor industry. The method has the advantages of good cleaning effect, simple operation, and can be removed for complicated devices and containers; but the method also has the disadvantages of high noise and easy breakage of the transducer.

This method can effectively remove organic, particulate, and metal ion impurities on the surface of the silicon wafer by utilizing the mechanical action of high-frequency sound waves, the cavitation effect of the solution, and the complexation reaction of chemical reagents. Using a similar method, BongKyun et al. used a 0.83 MHz megasonic wave to clean the silicon wafer, which is more excellent and can remove particulate impurities below 0.3 μm.

Silicon Wafer Wet Cleaning
Silicon Wafer Wet Cleaning

Double Flow Spray for Silicon Wafer

The dual-flow atomizing nozzle cleans the silicon wafer by using a nozzle to scan the silicon wafer back and forth with the rotating arm, and the silicon wafer rotates clockwise. The dual-flow nozzle uses a high-pressure, high-speed jet of gas to impinge a vulgar flow of liquid, destroying the surface tension of the liquid and the van der Waals bond and hydrogen bond between the liquid molecules, causing the liquid to atomize and become nanometer-sized droplets, which are ejected at high speed through the nozzle under the action of high pressure air.

Ozone Microbubble Method for Silicon Wafer

The high activity and strong oxidizing properties of ozone can remove organic and particulate impurities on the surface of the Si wafers. Ozone is dissolved in water to form a highly reactive OH group, and the OH group chemically reacts with the organic substance to remove organic impurities on the surface of the silicon semiconductor wafer. At the same time, the surface of the silicon product is covered with an atomic-level smooth oxide film, which effectively isolates the re-adsorption of impurities.

This method has an excellent cleaning effect, basically removes organic and particulate impurities, and meets the requirements of general silicon wafer cleanliness. At the same time, ozone microbubble cleaning produces less polluting waste and high cleaning efficiency, and can be used for cleaning large-scale circuits, silicon wafers and LEDs.

For more information, please visit https://www.sputtertargets.net/.

Sputter Targets for the Chip Industry

Every era has some materials to follow the mainstream trend to become the leader in the industry. Under the current situation, the development of the chip industry as a high-tech commanding point has important strategic significance, and the sputter target is a necessary raw material for the manufacture of ultra-large-scale integrated circuits. Therefore, the sputtering target material may be representative of the material emerging from this mainstream trend.

In the chip industry, which is a high-tech high point, sputter targets are essential raw materials for the manufacture of very large scale integrated circuits. Very large scale integrated circuits are those with more than 100,000 components integrated on a single chip, or more than 10,000 gates. With this technology, an electronic subsystem and even the entire electronic system can be “integrated” on one chip to complete various functions such as information collection, processing, and storage. What is repeatedly used in the manufacturing process of ultra-large-scale integrated circuits is the sputtering process belonging to physical vapor deposition (PVD) technology, which is also one of the main techniques for preparing electronic thin film materials.

The principle of the sputtering process is to utilize the ions generated by the ion source to accelerate the polymerization into a high-speed ion current in a vacuum to bombard the solid surface, and the kinetic energy exchange between the ions on the surface of the ion and the solid surface causes the atoms on the solid surface to leave the target and deposit on the substrate to form a nano/micro film.

The bombarded solid is the sputtering target, which is simply like a printing mold. The quality of the target plays a crucial role in the performance of the film, which directly determines the quality and performance of downstream semiconductor chips, flat panel displays, solar cells and other electronic devices or optical components. Therefore, the sputter target is the key raw material in the whole process.

Sputtering targets can be classified according to their chemical composition, geometry and field of application. Targets with different compositions (aluminum, copper, stainless steel, titanium, nickel targets, etc.) can be divided into different film systems (superhard, wear-resistant, anti-corrosion alloy films, etc.); if divided according to their application fields, they can be divided into It is recording medium targets, semiconductor targets, display film targets, superconducting targets, and optical targets.

The target production process includes two processes of “material purification” and “target preparation”. During the purification process, it is necessary to ensure the reduction of impurity content in the target, and the preparation process needs to ensure the surface level of the sputter coater target.

Sputtering targets for high-end applications have very high technical thresholds and are very complex to prepare. First of all, it is necessary to carry out process design according to performance requirements, and then carry out repeated plastic deformation, heat treatment, precise control of grain, crystal orientation and other indicators, and then through welding, machining, cleaning and drying, vacuum packaging and other processes.

For more information, please visit https://www.sputtertargets.net/.

What are the Uses of Metal Sputtering Targets?

What is the “target”?

The target refers to the target material. They can be used in high-energy laser weapons; different power densities, different output waveforms, and different wavelengths of lasers can have different killing effects when interacting with different targets. Another major use for them is for sputtering in physical film coating.

What is the “sputtering target”?

Magnetron sputtering coating is a new type of physical vapor deposition method, and its advantages in many aspects are quite obvious compared with the earlier evaporation coating method. As a relatively mature technology that has been developed, magnetron sputtering has been applied in many fields. Sputtering targets serve as source materials in magnetron sputtering coatings.

sputtering target in lcd

What are the application areas?

1: Microelectronics field

2: Target for flat panel display

3: Targets for storage technology

Sputtering materials are mainly used in electronics and information industries, such as integrated circuits, information storage, liquid crystal displays, laser memories, electronic control devices, etc.; they can also be used in the field of glass coating; they can also be applied to wear-resistant materials, high temperature corrosion resistance, high-grade decorative products and other industries.

The technological development trend of target materials is closely related to the development trend of thin-film technology in the downstream application industry. As technology in the application industry improves on film products or components, target technology should also change. In recent years, flat panel displays (FPDs) have largely replaced the market for computer monitors and televisions, which are mainly cathode ray tubes (CRTs), and will greatly increase the technical and market demand for ITO targets.

Stanford Advanced Materials (SAM) Corporation is a global supplier of various sputtering targets such as metals, alloys, oxides, ceramic materials. For more information, please visit https://www.sputtertargets.net/.

Applications of High Purity Copper Sputtering Target

The copper sputtering target is a coating material made of metallic copper, which is suitable for DC bipolar sputtering, three-pole sputtering, four-stage sputtering, radio frequency sputtering, counter target sputtering, ion beam sputtering, and magnetron sputtering, etc. It can be applied to manufacture reflective films, conductive films, semiconductor films, capacitor films, decorative films, protective films, integrated circuits, displays, and etc. Compared with other precious metal sputtering targets, the price of copper targets is lower, so the copper target is the preferred target material under the premise of satisfying the function of the film layer.

Copper sputter targets are divided into the planar copper target and rotary copper target. The former is sheet-shaped, with round, square, and the like; the latter is tubular, and the utilization efficiency is high.

planar and rotory copper sputtering target

High-purity copper sputter targets are mainly used in electronics and information industries, such as integrated circuits, information storage, liquid crystal displays, laser memories, electronic control devices, etc.; they can be applied to the field of glass coating; they can also be applied to wear-resistant materials, high-temperature corrosion resistance, high-end decorative supplies and other industries.

Information storage industry: With the continuous development of information and computer technology, the demand for recording media in the world market is increasing, and the corresponding target media for recording media is also expanding. Related products include hard disks, magnetic heads, and optical disks. (CD-ROM, CD-R, DVD-R, etc.), a magneto-optical phase-change optical disc (MO, CD-RW, DVD-RAM).

Integrated circuit industry: In the field of semiconductor applications, sputtering targets are one of the main components of the world target market. They are mainly used for electrode interconnect film, barrier film, contact film, optical disk mask, capacitor electrode film, and resistive film, etc.

Flat-panel display industry: Flat panel displays include liquid crystal displays (LCDs), plasma displays (PDPs), and the like. At present, LCD is the main market in the flat panel display market, and its market share exceeds 85%. LCD is considered to be the most promising flat display device and is widely used in notebook monitors, desktop monitors and high definition televisions. The manufacturing process of the LCD is complicated, in which the reflective layer, the transparent electrode, the emitter and the cathode are all formed by a sputtering method, and therefore, the sputtering target plays an important role in the manufacture of LCD.

For more information, please visit https://www.sputtertargets.net/.

Introduction to Aluminum, Aluminum Alloy and Aluminum Sputtering Target

Aluminum is a light metal with low density (2.79/cm3), good strength and excellent plasticity. As for aluminum alloy, the strength of super-hard aluminum alloy can reach 600Mpa, and the tensile strength of ordinary hard aluminum alloy can reach 200-450Mpa, which is much higher than steel in steel. Therefore, aluminum and aluminum alloy are widely used in machinery manufacturing.

The conductivity of aluminum is second only to silver and copper, so aluminum is used in the manufacture of various conductors. Aluminum also has a good thermal conductivity that can be used as a variety of heat dissipating materials. Besides, aluminum has good corrosion resistance and excellent plasticity, and is suitable for various pressure processing.

Aluminum alloy

Aluminum alloy can be divided into the deformed aluminum alloy and the cast aluminum alloy according to the processing method.

The deformed aluminum alloy can be further divided into a non-heat treatable reinforced aluminum alloy and a heat treatable reinforced aluminum alloy. Non-heat-treated reinforced aluminum alloy cannot improve the mechanical properties by heat treatment, and can only be strengthened by cold working deformation. It mainly includes high-purity aluminum, industrial high-purity aluminum, industrial pure aluminum and rust-proof aluminum. The heat-treatable reinforced aluminum alloy can be improved in mechanical properties by heat treatment such as quenching and aging, and can be classified into hard aluminum, wrought aluminum, super-hard aluminum, and special aluminum alloy. The aluminum alloy can be heat treated to obtain good mechanical properties, physical properties and corrosion resistance.

Cast aluminum alloy can be divided into aluminum-silicon alloy, aluminum-copper alloy, aluminum-magnesium alloy and aluminum-zinc alloy according to chemical composition. Cast aluminum alloy is classified into four types according to the main elements other than aluminum in the composition: silicon, copper, magnesium and zinc.

Pure aluminum products

Pure aluminum products are divided into two categories: smelting and pressure processing. The former is represented by chemical composition Al, and the latter is represented by LG (aluminum, industrial). The aluminum sputtering target is a kind of pure aluminum product.

Pressure processing aluminum alloy

Aluminum alloy pressure processing products are divided into seven categories: rustproof (LF), hard (LY), forged (LD), superhard (LC), coated (LB), special (LT) and brazed (LQ). The state of the commonly used aluminum alloy material is three types of annealing (M igniter), hardening (Y), and hot rolling (R).

Aluminum sputtering target

The aluminum sputtering target is one of the sputtering targets used in the vacuum coating industry, and is therefore called aluminum sputtering target. The aluminum target is obtained after a series of processing of high-purity aluminum. It is available in a specific size and shape, which is mounted on a vacuum coater to form a film on the surface of the substrate by sputtering.

Please visit https://www.sputtertargets.net/ for more information.

Boron Nitride Crucible Use Guide

Boron nitride crucible is used at a temperature of approximately 1800 degrees under vacuum and at a temperature of approximately 2100 degrees under atmospheric protection, making it ideal for ultra-high temperature forging.

BN crucible is best used in the nitrogen or argon atmosphere and has the longest life in that environment. The thermal resistance of boron nitride crucible is good. Even if the temperature suddenly becomes cold when it is used at 1500 degrees, it will not crack; after holding it for 20 minutes in a 1000 degree furnace, take it out and blown and quenched it continuously for hundreds of time, it won’t crack, either.

bn crucible

Precautions for use

1 When boron nitride is used in air, the temperature should not exceed 1000 degrees; if the temperature exceeds 1000 degrees, the contact surface of boron nitride and oxygen will oxidize and peel off.

2 Boron nitride is easy to absorb moisture, so BN crucible can not be stored in wet areas, can not be washed, but can be directly wiped with sandpaper or scrubbed with alcohol.

3 Applications of boron nitride

[Available materials]

  1. Ferrous metal: iron, copper, aluminum, nickel, magnesium, bismuth, zinc, etc., alloy FE-CO-NI-SI CO-ZR-NB
  2. Does not react with water or acid at normal temperature. Slowly hydrolyze with water to form boric acid and ammonia
  3. Rare earth, nitride

bn crucible-2

[Unavailable materials]

  1. Antimony trioxide, chromium oxide pentoxide, molybdenum trioxide, arsenic trioxide, titanium carbide, etc.
  2. The high-lead glass glaze melts in the air at 800-950 °C, but it does not react under the protection of nitrogen or inert gas. 3. Boron phosphate erodes boron nitride in 1400 ° nitrogen, and reacts with hot concentrated or molten alkali and hot chlorine.

For more information about evaporation e-beam source used crucibles, please visit https://www.sputtertargets.net/e-beam-source-used-crucibles.html.

Application of Indium Tin Oxide in Anti-Reflection Film Design

The indium tin oxide (ITO) transparent conductive film belongs to an N-type oxygen-deficient semiconductor material. It has low absorption of visible light and has high visible light transmittance, excellent infrared reflection performance and microwave attenuation performance in the mid-far infrared range. ITO transparent conductive film has become an important optical component in the field of optoelectronic devices due to its excellent photoelectric performance.

indium tin oxide evaporation pellets

ITO materials have long been used as transparent conductive films in the form of single-layer films, but their average transmittance in the visible portion is very low, generally less than 90%, and the reflectance is high, affecting its display and electromagnetic shielding applications. If the transmittance in the visible light region is improved, the application of the ITO transparent conductive film will be more extensive.

The ITO film is usually made of the indium tin oxide sputtering target and the indium tin oxide evaporation material. The use of the ITO film as one of the antireflection film systems can greatly increase the transmittance of the transparent conductive film in the visible light portion, and solves the problem that the transparent conductive film is generally low in visible light transmittance. A multilayer anti-reflection film containing TTO material was prepared by a low-pressure reactive ion plating method, and a transparent conductive film having an average visible light transmittance of 95.83%, a maximum transmittance of 97.26%, and a sheet resistance of 13.2 to 24.6 Ω was obtained. The anti-reflection film largely alleviates the contradiction between the conductivity and the transparency of the transparent conductive film, and the ITO transparent conductive film has more useful practical value and application prospect in the field of application.

indium tin oxide uses

For more information, please visit https://www.sputtertargets.net/.

Rotatable Sputtering Targets Merits and Weakness

Sputtering is a high-speed process where superfast ions hit a sputtering target and dislodge minuscule particles that in turn coat a thin film on substrates like architectural glass, LED televisions and computer displays.

Rotatable sputtering target, or rotatory target, is a commonly used target shape in magnetron sputtering. It is generally cylindrical, with a stationary magnet inside, and a slow magnetic field, which allows the sputtering rate to be uniform and the target utilization rate to be high. Rotating targets are commonly used for coating solar cells, architectural glass, automotive glass, semiconductors, and flat-panel TVs.

The main advantage of the rotatable target is the high utilization of the target, which means that the rotating target can solve the problem of low utilization of the planar target.

Rotatory Copper (Cu) Sputtering Target
Rotatory Copper (Cu) Sputtering Target

For a planar sputtering target, the target utilization of the normal cathode can reach 25%, and the special design of the magnet bypass with the target back can increase the target utilization to about 40%. Despite this, the utilization of planar targets is still not high. However, the utilization of cylindrical rotating targets is typically in the range of 75% to 90%, much higher than planar targets. However, when the rotating target is used for large-area coating, the uniformity of the surface of the film layer is poor and it is difficult to meet the requirements, which is the biggest disadvantage of the rotating target.

Materials Planar Rotatory
Metal Planar molybdenum target, planar copper target, planar titanium target, planar tungsten target, planar zirconia target

 

 Rotatory molybdenum target, rotatory copper target, rotatory titanium target, rotatory tungsten target, rotatory zirconia target

 
Oxides Planar SiO2 Sputtering Target Rotatory ATO Sputtering Target, rotary Nb2Ox sputtering target, rotatory TiOx sputtering target, rotatory Al2O3 sputtering target
Alloy Planar Cr-Ta sputtering target, planar Ti-Al-Si sputtering target SnO2-Sb2O3 rotatory sputtering target

For more information, please visit https://www.sputtertargets.net/.

Sputtering Target Materials for Vacuum Thin Film Coating

The sputtering target is a key required material for vacuum film coating. It refers to a material that can ionize the surface by the current-binding magnetic field.

Almost all sputter coating equipment uses a powerful magnet to spiral the electrons to accelerate the ionization of the argon around the target, resulting in an increased likelihood of collision between the target and the argon ions, thereby increasing the sputtering rate.

Typically, most metal plating uses DC sputtering, while non-conductive ceramic materials use RF sputtering. The basic principle is that argon (Ar) ions are struck against the target surface by glow discharge in a vacuum, and cations in the plasma are accelerated as a sputter material to the surface of the negative electrode. The impact will cause the material of the target to fly out and deposit on the substrate to form a film.

Generally, the sputter coating process has several features:

（1）Many materials can be deposited into thin film materials by sputtering, including metals, alloys, insulators, and the like.

（2）Under appropriate conditions, different component target materials can be made into films of the same material.

（3）Oxides or other compounds of the target substance and gas molecules can be prepared by adding oxygen or other reactive gas to the discharge atmosphere.

（4）Highly accurate film can be obtained by controlling the magnitude of the input current and the length of the sputtering time.

（5）For large-area coatings, sputter deposition is definitely superior to other coating processes.

（6）In the vacuum vessel, the sputtered particles are not affected by gravity, and the positions of the target and the substrate can be freely aligned.

（7）The bond strength between the sputter-coated substrate and the film is 10 times or more the adhesive strength of a general evaporated deposited film. Furthermore, since the sputtered particles have high energy, the surface of the film is continuously diffused to obtain a hard and dense film. At the same time, high energy allows the substrate to obtain a crystalline film at a lower temperature.

（8）The nucleation density at the initial stage of film formation is high, and an extremely thin continuous film of 10 nm or less can be produced.

（9）Sputtering targets have a long service life and can be continuously produced over a long period of time.

（10）The sputtering target can be made into various shapes. By special design of the shape of the target, the sputtering process can be better controlled and the sputtering efficiency can be most effectively improved.

For more information, please visit https://www.sputtertargets.net/.

Pros and Cons of Ion Beam Sputtering

Advantage

1 Ion beam sputtering relies on momentum exchange to make atoms and molecules of solid materials enter the gas phase. The average energy generated by sputtering is 10 eV, which is about 100 times higher than that of vacuum evaporation. After deposited on the surface of the substrate, these particles still have enough kinetic energy to migrate on the surface of the substrate, so that the film has good quality and is firmly bonded to the substrate.

2 Any material can be coated by ion beam sputtering, and even a high-melting material can be sputtered. For alloys and compound materials, it is easy to form a film having the same ratio as the composition of the sputtering target, and thus sputter coating is widely used.

3 The incident ions of the ion beam sputter coating are generally obtained by a gas discharge method, and the working pressure is between 10-2 Pa and 10 Pa. Sputtered ions often collide with gas molecules in the vacuum chamber before flying to the substrate, so the direction of motion randomly deviates from the original direction. Sputtering is generally ejected from a larger sputter target surface area and is, therefore, more uniform than that obtained by vacuum coating. For coating parts with grooves, steps, etc., the sputter coating can reduce the difference in film thickness caused by the cathode effect to a negligible extent. However, sputtering at higher pressures will result in more gas molecules in the film.

ion beam sputtering deposition

4 Sputtering can precisely focus and scan the ion beam, change the target material and substrate material while maintaining the characteristics of the ion beam, and independently control the ion beam energy and current. Since the energy of the ion beam, the beam size and the beam direction can be precisely controlled, and the sputtered atoms can directly deposit the film without collision, the ion beam sputtering method is suitable as a research method for thin film deposition.

Disadvantage

The main disadvantage of ion beam sputtering is that the target area of the bombardment is too small and the deposition rate is generally low. What’s worse, ion beam sputter deposition is also not suitable for depositing a large-area film of uniform thickness. And the sputtering device is too complicated, and the equipment operating cost is high.

For high purity sputtering target inquiry, please visit Stanford Advanced Materials.