Silicon Substrate Backgrinding Services

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Silicon Wafer Backgrinding Service

A scientist requested a quote for the following:

We need Silicon Wafer (12” dia) Back-grinding service. Thickness required is 75 um. 8000 Wafers/month required. Could you please provide.

UniversityWafer, Inc. Quoted:

Currently we do 12'' Silicon Back-grinding for Interl, TSMC, Samsung etc.,approx. 20 years experience in 8'' and 12'' Si process.

Silicon Wafer (12” dia) Back-grinding service. Thickness 75 um removed from the back side .

UniversityWafer, Inc. can background our own wafers or your wafers and, or polish them as well.

Please reference #257956 for pricing.

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Key Silicon Backgrinding Terms

  • wafer grinding 
  • wafer refinishing
  • wafer recycling
  • wafer thickness
  • wafer surface
  • wafer thinning 
  • treated wafer
  • semiconductor wafer
  • backgrind wafer
  • target wafer
  • desired wafer 
  • silicon wafers
  • wafer backgrinding
  • thinner wafers
  • thin wafers    


What Does Backgrinding Silicon Wafers Do?

You can clean silicon wafers by backgrinding them, but you should consider the following guidelines before you start. Here are some materials you should use, as well as the process. Also, you need to make sure that you clean your wafer before applying tape. Non-UV tape is weak and prone to air bubbles. And don't use it on expensive wafers. Nevertheless, non-UV tape is relatively cheap, and can be easily obtained from a local supplier.

How do you Think Silicon Wafers?

A typical semiconductor wafer may be as thick as 775 um when it is first manufactured. However, it can become thinner through the backgrinding process. During this process, the wafer is placed on a rotary table and is rolled down toward a lapping surface. The wafer is then resurfaced using deionized water, removing excess material. To prevent the front surface of the wafer from damage, a protective tape is applied to its front surface.

In this process, a silicon wafer is bonded to a glass substrate using electrostatic bonding. This process creates a strong, stable, and close contact at the silicon and glass interface. This bonding method is only possible if one silicon wafer has a glass layer. Because glass has the same thermal expansion coefficient as silicon, it is biocompatible and is used extensively in biomedical applications.

Materials for backgrinding silicon wafer - Several types of grinding wheels are available for backgrinding of silicon wafers. The most common grinding wheel is a high-speed circular rotary table. This tool will backgrind silicon wafers and achieve the desired shape of the edges. The edge profile must be consistent with the SEMI M1-0707 standard to ensure proper sizing and bonding.

What is the Process to Backgrind Silicon Wafers?

Backgrinding of silicon wafers is a process for making semiconductor devices that thins a device wafer before dicing it into individual dies. These thin silicon chips are often used in applications such as smart labels and RFID tags. This process also makes it easier to process wafers that need high-precision fabrication. Backgrinding also reduces the amount of surface roughness in silicon wafers.

The material used in backgrinding silicon wafers may vary in size from 4 to 130 micrometers in diameter. For example, a preferred material is a silicon sphere with a diameter of approximately 44 micrometers. It is important to note that this type of material is not suitable for every application, and a variety of methods are available. The data listed above are typical and cannot be guaranteed.

A typical backgrinding process begins with the removal of the bulk of excess material from the wafer. The wafer is then placed on a rotary table and rotated downwards toward a lapping surface. The backgrinding process ensures that the desired thickness of the wafer is achieved. The starting thickness of a typical silicon wafer is approximately 775 um, and it may range between 50 and 100 um.

Backgrinding silicon wafers is necessary for ultra-compact electronic products. As wafers become thinner, manufacturers can fit more components on the same surface, saving space and money. To achieve this, backgrinding is a process that must be done before the wafers are diced. The process is also a crucial part of the manufacturing process, and MTI Instruments plays an essential role in this process.

What are the Results of Silicon Backgrinding?

The results of backgrinding silicon wafers are largely dependent on the grind-order and other process parameters. By back grinding a silicon wafer, the overall thickness decreases from 800 to 700um, and the resulting thin wafer can be stacked four to six times or up to 32 times. This multi-layer structure of a semiconductor chip is called a Multi Chip Package (MCP). The final height of such a MCP must be 1.4mm.

The researchers also studied the effect of tapes on the subsurface damage of back-ground silicon wafers. They found that a thin layer of amorphous material is created above the polycrystalline layer and below the polycrystalline layer. The thickness of the strained crystalline layer is estimated from the warpage measurements of the silicon wafer, and the stress in the amorphous layer is directly measured using Raman spectroscopy. The researchers developed an analytical model to investigate the effects of back-grinding on the stress propagation with depth. Their measurements suggest that a thin layer of silicon remains on the surface after dry etching.

The backgrinding process of silicon wafers is a multi-step process to produce ultra-thin silicon wafers. The first step is coarse grinding, which removes the majority of the excess material from the wafer. After this, finer grit wheels are used to polish the silicon wafer to the desired thickness. It is important to note that backgrinding is a highly complex process that can increase production while compromising wafer strength.

How do you Clean Silicon Wafers after Backgrinding?

Cleaning a silicon wafer for backgrinding is an intricate process. Due to their fragile nature, these pieces are easily contaminated and require various processes. A three-step procedure is usually used to clean the substrate by removing oxidized residues. A solution containing sulfuric acid and hydrogen peroxide is used in this process to remove photoresist films and other contaminants. The final step in the cleaning process is a thorough ozone wash.

The most common cleaning process is called the RCA clean. This involves soaking a silicon wafer in a caustic solution for up to ten minutes. The solution dissolves dirt and impurities and allows the wafer to be cleaned thoroughly. Ultrasonic cleaning can take about 30 minutes, but the exposure time is too long. Excessive ultrasonic energy can cause damage to the crystal lattices and cause an oxide layer to form on the surface of the silicon wafer.

RCA cleaning is a three-step process that is crucial in backgrinding silicon wafers. First, the silicon wafer is soaked in a solution of hydrogen peroxide and sulphuric acid. This acid removes all organic materials and heavy metal ions from the surface of the silicon wafer. Next, the silicon wafer is dipped in a hydrochloric acid and water solution. This process is repeated a few times until the surface is clear and impurity-free.

Scratch Pattern on the Backside of Silicon Wafers

A defect on the backside of a silicon wafer can lead to a shattering wafer if it is not detected in time. A slight defect in the edge of a silicon wafer will cause thermal stress to begin cracks in the silicon. When this happens, a semiconductor fab will have to shut down a tool to repair the defect. Thankfully, semiconductor fabs are using a process called wafer-edge inspection.

This process is also known as striated extrinsic gettering. The objective is to create deep scratches on the backside of silicon wafers, and it involves several methods. Among them are spiral particle paper method and phonographic technique. Poly backside processing produces the best results because it does not suffer from abrading, while a sand paper method requires high-quality abrasives. However, this method is the most expensive and takes the longest.

The depth of scratch pattern is directly related to the strength of semiconductor die. Therefore, the finished backside surface of the silicon wafer should be smooth to minimize the impact of scratches. In addition, the thickness of the scratches is important because it directly affects the chip quality. For that reason, it is imperative to ensure that backside scratch patterns do not exceed ten nanometers in order to preserve the integrity of the silicon die.

What is Isotropic and Anisotropic Etching?

Chemical-based etching processes are used to create various surfaces on silicon wafers. There are two main types: anisotropic etching and isotropic etching. Isotropic etching produces the same etch rate for all crystal orientations, while anisotropic etching requires a voltage. Both processes are effective, but one is preferred for the manufacturing of microelectronic devices and semiconductors.

Oxidation with O2 requires a higher temperature, and anisotropic etching is more difficult. O2 molecules become reactive when exposed to higher temperatures. Conversely, XeF2 atoms are highly reactive at lower temperatures. In addition, both types of etching require a high flow rate, which means that the rates must be consistent throughout the wafer. Using a low-pressure oxygen environment helps to control the etching rate and increase the efficiency of the process. Anisotropic etching results in higher device yields, but it is also more challenging to control.

This method produces structures with a perfect convex corner, as compared to isotropic etching. An anisotropic etching process can be a useful tool for designing semiconductor devices. For example, silicon direct bonding is a technique for assembling silicon wafers together using pressure. An annealing temperature of approximately 400°C makes the silicon atoms more prone to bonding to each other.

Video: Wafer Backgrinding