The article presents an overview of the Processes involved in Silicon Wafer Inspection and Lapping. You will learn about Materials and Optical defect measurement.
Furthermore, you will learn about the Monitoring of Quality. In addition, you will be able to use the information to choose the right process for your particular application. To learn more, read on. Below are some examples of different processes. Read on to learn more!
The process of making a semiconductor begins by melting a large slab of silicon and then slicing it into thin wafers. This process, known as semiconductor slicing, uses a laser beam to slice the wafer into individual silicon chips.
The area around the laser beam is cleaned with cooling water to prevent contamination. After the silicon boules are cleaned, the wafers are then polished and sliced into thin slices.
A silicon wafer is lapped after it is sliced, to remove saw marks and damage. Then, a chemical called sodium hydroxide is applied to the wafer to remove the surface damage.
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After this, it is cleaned and etched to remove any visible damage. After lapping, a process known as critical edge grinding is used to round the edge of the silicon substrate.
The manufacturing process of silicon begins with the growth of monocrystalline silicon, which is then ground and sliced into thin slices. The final step of the process is to remove any defects. Silicon wafer lapping and inspection involve using specialized materials and equipment.
The process is very complex, with many steps, from growth to inspection. Here are the main types of materials used for silicon manufacturing and inspection. Using the correct materials is crucial for the success of any silicon manufacturing process.
The manufacturing process begins with the growth of a silicon ingot. The ingot is then ground to a rough diameter, usually 200 to 300 mm, and marked with a notch to identify its orientation. Next, it is sliced with a diamond edge saw, minimizing thickness variations and bow and warp defects.
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The wafer is then cleaned and shipped to the next operation. After lapping, silicon wafers undergo a variety of machining processes. These include refractivity testing, edge profiling, and corrosion inspection.
Optical defect measurement
The first optical system 10 irradiates the wafer surface and receives the vertical scattered light due to the defects. The resulting information is processed to obtain the luminance information of the defects at a predetermined location.
The optical system then scans the entire surface of the wafer and acquires the entire defect information. Depending on the type of defect, the defect information is subjected to differential or filter processing.
Optical defect measurement during silicon wafer inspection and lapping is performed using two different systems. The first optical system irradiates a predetermined position on the surface of a wafer, while the second optical system irradiates an alternate location.
A parallel light irradiation light source 21 is installed at an angle to the wafer’s surface. The second optical system 20 includes a second light receiving unit 22. This unit reflects the beam of the first optical system onto the pit candidate, where it changes the brightness.
Monitoring of quality
Micron-scale inspection of semiconductor wafers requires high-quality measurements. These measurements must be accurate and reliable in harsh industrial environments. The CHRocodile 2 IT provides a non-contact measurement of varying thicknesses and materials.
This camera measures SIC, as well as the width, depth, and tilt of the die. The resulting measurements are crucial for process feedback and reducing costs. Moreover, the CHRocodile 2 IT offers easy refitting of the sensor for a better fit.
A blanket film defect capability is an essential capability for silicon wafer quality monitoring. It helps manufacturers qualify process tools and monitor wafer quality. Impurities control is a fundamental requirement for better device performance in the electronics industry. However, it is not always easy to monitor silicon wafer quality.
Silicon Wafer Cleaning and Silicone Wafer Polishing
There are several processes for silicon wafer cleaning and polishing. Here we will talk about the Wet method and Chemical mechanical planarization (CMP).
The Wet method of silicon wafer cleaning and surface polishing is a proven and effective way to produce an optimum surface finish. By creating a ‘passivation layer’ on the silicon wafer’s surface, it minimizes the possibility of particles and other impurities attaching to the silicon surface. As a result, the surface of the silicon wafer is more stable and ready for further processing.
This method has many advantages over extreme ultraviolet lithography, largely because it doesn’t depend on wetting the surface. The cleaning process doesn’t limit the slurry’s cleaning abilities by the film or hydrophobic/hydrophilic properties.
Consequently, it is an excellent choice for cleaning large-scale quantities of silicon wafers. Nevertheless, the process is often less efficient than other methods, and a higher level of surface cleaning is recommended.
The Wet method of silicon Wafer Polishing involves the use of a chemical solution composed of hydrofluoric acid. This solution is highly acidic and should contain no sulfur or chemicals to avoid damage. The silicon wafer is immersed in the solution for six to ten minutes, before being rinsed with deionized water. The wettability test helps determine whether or not all impurities have been removed.
Chemical mechanical planarization (CMP)
CMP is a chemical manufacturing process that involves the removal of a thin layer of material from a surface. The process is based on a mechanism that utilizes chemical reactions at the metal surface. Several chemical reactions are outlined below.
These reactions can be useful in the development of novel CMP processes to meet the needs of the coming technology nodes. Chemical mechanical planarization (CMP) can be used for a variety of applications, including the cleaning and polishing of silicon wafers.
CMP utilizes chemical and mechanical interactions to achieve desired removal rates, selectivity, and planarity. The substrate is pressed onto a polymeric pad, typically made of polyurethane, which has been designed to be hardened or textured to minimize damage to the wafer.
The slurry is then transported into the grooves of the polyurethane pad. The high-speed rotation creates these chemical and mechanical interactions. Various types of chemical and abrasive compounds are used during the process.
The process can cause significant environmental impacts. CMP wastewater is a major source of NM in the environment and in sewer systems. In fact, approximately 5% of the mass of CeO2 may end up in the natural environment.
To reduce the environmental impact of this process, various methods are being researched. Eventually, these alternative methods may replace traditional CMP technology. There are many environmental benefits of CMP, but it is important to assess the environmental impact before adopting the technique.
Both processes entail cleaning silicon wafers to remove particles and contaminants. The cleaning process reduces the chances of defects in the finished product. While the etching process requires that the surface of the wafer is free from impurities, these deposited particles can impact the diffusion process.
Furthermore, wafer cleaning decreases the dimensions of the integrated circuit element. Thus, reducing the environmental impact of silicon wafer cleaning and polishing is an important part of manufacturing semiconductors.
Solvent cleaning is considered to be the most efficient cleaning process. It removes most of the particles but leaves a residue on the silicon wafer surface. Solvents used for cleaning silicon wafers include acetone, methanol, and a combination of both.
Solvents are flammable chemicals and can cause severe environmental impact if used in large amounts. In addition to solvent cleaning, the ozone micro-bubble method can also be used to remove impurities from silicon wafers.
Before high-temperature processing steps, the silicon wafers must be cleaned. In RCA clean, the silicon wafers are heated to 75-80 degrees Celsius, where the RCA cleaning solution reacts with the metal and changes its zeta potential. The resulting layer of silicon dioxide protects the silicon wafer while leaving a thin layer of oxidized silicon on the surface.