What is Wafer Backgrinding and Its Benefits

In this article, we will explore the benefits and disadvantages of wafer backgrinding. We will also look at equipment, microstructure, and process. These factors will help you determine whether the process is the right choice for your semiconductor manufacturing needs. Let’s take a closer look at the process in order to understand what it involves and how it can help you develop your next product. So, go now and read on to discover more!

Process

The backgrinding of wafers involves a multi-step process. In a two-step backgrinding operation, the wafer is first started at 720 um in thickness and then is ground with a large grit to remove the bulk of excess material. Finer grit is then used to polish the wafer and achieve the desired thickness. The process typically uses dual spindles with grinding wheels mounted on each.

As the need for thin wafers has increased, the size of these wafers has also grown. More semiconductor manufacturers are utilizing 200-millimeter wafers in place of 150-millimeter wafers. This trend has made breakage of wafers a major problem. Not only is this costly, but it also compromises the benefits of using larger diameter wafers. Because of this, the backgrinding process must apply forces uniformly across the wafer.

The adhesive strength of backgrinding tapes is high, making them a valuable addition to wafer fabrication equipment. However, the adhesive strength of non-UV tapes is weak and can create gaps. The tapes used in backgrinding should be removed after the backgrinding process. Otherwise, the remaining tape residue can remain on the surface of the wafer. Non-UV tapes have poor adhesive strength and can cause air bubbles.

After applying the tape, the chuck is fitted with a backgrinding tool. The chuck has apertures for vacuum and backgrinding tape, which is applied to the wafer prior to backgrinding. The wafer is then washed and scrubbed thoroughly with the backgrinding tape. The whole process repeats until the wafers are all cleaned. If the process is completed correctly, the backgrinding tape will leave the wafers with a pronounced scratch pattern.

Equipment

In the back grinding process, the silicon wafer is first ground on the back surface, before being placed on a tape. Then, the process continues with finer grit, polishing and grinding the wafer to its desired thickness. Typically, wafers with a diameter of 200 mm are background in two steps. The first step is tape lamination, which applies an adhesive tape to the front surface of the wafer. This step is essential to protect the wafer, as the silicon compound spreads out in all directions during back grinding. A tape lamination is a crucial process that enables the wafer to be protected against the damaging effects of the grinding process.

In addition to back grinding, other technologies are available for producing ultra-thin die. Typical backgrinding solutions from DISCO include the machine, the grinding wheel, the protective tape and the processing conditions. For thick wafers, a process called “super fine” is used. On the other hand, a method called “wafer backgrinding” is used for wafers that are thinner than 50 mm.

The underlying technology of wafer backgrinding requires accurate measurements, which can be derived from the detailed description given above. For example, a 300 mm wafer may contain 100-um logic gates, 50-um DRAM memory, or even thirty-um MEMS memory. During backgrinding, a characteristic scratch pattern is left on the wafer. This pattern is predominant on certain locations on the wafer.

Cost

Wafer backgrinding is a crucial part of the semiconductor manufacturing process. Its benefits are multiple, including lower cost per semiconductor chip. It can also reduce the thickness of the wafer, a key goal in the semiconductor manufacturing process. The costs associated with backgrinding can be reduced by employing various grinding methods. This article will explore the cost and benefits of backgrinding. It also offers tips on reducing wafer grinding time.

The global market for wafer backgrinding tape is expected to reach USD 201.6 million by 2020 and expand at a CAGR of 4.9% from 2019 to 2026. The key benefits of backgrinding include reducing the thickness of wafers, allowing for high-density packaging, and stacking of integrated circuits. Backgrinding is a highly integrated process in semiconductor fabrication.

In addition to decreasing the thickness of wafers, backgrinding can create damage to the substrate, including dislocations, microcracks, and residual stress. This subsurface damage can degrade the mechanical properties of wafers, causing assembly challenges and difficulty. Additionally, the low fracture strength of ultrathin silicon wafers can affect the ability of other processes to process the wafer, such as dicing and packaging. This is where damage-free postgrinding comes in handy.

In order to improve wafer quality, wafer fabs have made it a priority to optimize their backgrinding process. Engineered bonding systems reduce subsurface damage and surface stresses, while improving wafer strength. Initial truing of the grinding wheel is a key element in this process, as it helps to ensure uniformity of the wheel from grind to grind, thereby reducing waste in dressing.

Microstructure

Backgrinding is a key technology in the fabrication of semiconductor devices. The process of backgrinding a wafer allows the metallization of the backside of the wafer. This process results in a layer of metal on the backside of the wafer, which serves as a thermal interface between the die and heat dissipation device. The metal layer is typically deposited as a layer of solder between the backside of a wafer and the heat dissipation device.

During encapsulation, stress may result in cracks or other damages on the surface of the wafer, which can affect the performance of the wafer. Backgrinding is an important process for removing such damages, as the damage may spread to active regions. It also removes surface imperfections, such as surface flaws, which can affect the performance of the wafer. In addition to surface flaws, backgrinding allows a wafer to be more uniform, meaning that the surface does not appear smooth or bumpy.

While back grinding does not affect the fracture strength of wafers, it increases the failure load, depending on the degree of the grind. Indentation load and depth are indicators of fracture strength and mechanical stress in low-k stacks. The mechanical stress generated during backgrinding processes causes microcracks to form on the backside of the wafer, which improves its structural integrity. Further, backgrinding can increase the level of nanoindentation, a critical parameter in wafer fabrication.

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Recyclability of silicon residues

Recyclability of silicon residues from waffle backgrinding has been investigated for several years. These residues are the result of grinding the silicon wafers and are a significant source of environmental pollution. While there are many advantages to recycling these materials, they are also costly. The following are some of the disadvantages associated with this method of silicon residue recycling. Listed below are some of the main disadvantages of silicon backgrinding.

The waste silicon powder is in a slurry that includes working fluid, metals, and other impurities. Silicon powder waste is mixed with PEG or other organic solvents. Some silicon residues are too fine to be recycled and are disposed of as landfill. The remaining silicon residue is referred to as kerf. The waste is often used in manufacturing processes for a variety of applications.

Using the reclaimed silicon wafers can reduce the cost of production, increase the quality of a finished product, and preserve the environment. Because silicon wafers are so expensive, reclaiming them can help to keep costs down for the semiconductor industry. Reclaimed silicon wafers are thinner than virgin ones, but often offer the same performance as test grade wafers. Because of their low price, they are a viable alternative for university research departments.

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