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The semiconductor manufacturing process (back-end process)

Front-end and back-end processes in semiconductor manufacturing

The process of manufacturing semiconductors is similar to that of making small card-like printed matter, such as business cards.

In the case of business cards, the first step is to decide on a design, followed by printing many business card design patterns on a large sheet of paper. Finally, the printed material is cut into pieces and made into business cards.

The same is true for the semiconductor manufacturing process. Semiconductor manufacturing is divided into the design process, front-end process, and back-end process, with the design process being the design and the front-end process being the printing. The next step is to cut them into pieces.

Semiconductors go through a design process, and large-scale integrated circuits (LSI) are created on silicon wafers in the front-end process. The integrated circuit is then cut into individual chips in a back-end process. In this article, we will discuss the back-end process.

Click here for an article on "Front-end Process".

Processing performed in the back-end process of semiconductor manufacturing

In the back-end process, the semiconductor is cut out from the wafer and made into a product. In the front-end process, Large Scale Integrated (LSI) circuits with hundreds of semiconductors lined up on a wafer made from silicon ingots are created. In the back-end process, these integrated circuits are cut out one by one and processed in various ways so that they can be used as products.

The processing that takes place in the back-end process is as follows.

  • Dicing: The wafer is cut with a diamond blade and separated into individual chips. In the dicing process, the wafer is attached to a dicing tape, and a rotating circular diamond blade is used to separate the semiconductors from each other while spraying ultrapure water.

    In addition to the diamond blade method, there are other methods of dicing, such as the laser method, which cuts with a laser, the scribe method, which cuts by inserting scratch lines into the wafer to cause cracks, and the plasma dicing method, which etches with plasma to separate the wafer.

    If you are using dicing tape, the key point is that the tape holding the wafer in place will not be cut. After cutting, the dicing tape is stretched to create a clearance between the chips to facilitate removal and other operations.

  • Wire bonding: Fix the chip to the lead frame (die bonding). A lead frame is a thin metal support for a chip, and also serves as a terminal for mounting a semiconductor on a board.

    Some lead frames have the ability to diffuse heat, and in some cases, such as in the manufacture of power semiconductors, they are mounted on heat sinks instead of lead frames. In die bonding, adhesives such as silver paste are used.

    After die bonding, the wire bonding process connects the chip to the lead frame with a thin wire made of gold. This allows the chip to be wired through the lead frame.

  • Molding: Chips are very delicate products and can be affected by scratches, shocks, dust, and magnetism. Therefore, the chip is encased in epoxy resin to protect it from external influences. This is called molding or packaging.

    In recent years, however, smaller semiconductors are required as products become smaller. The answer is bare dies, which are semiconductors that have not been packaged. The advantage of bare dies is that you can stack them on a substrate in three dimensions, but they also have the disadvantage of low chip yield.

After dicing, wire bonding, and molding, semiconductor products go through an inspection process before being shipped.

Dicing
Semiconductor manufacturing process (back-end process) dicing
Wire-bonding
Semiconductor manufacturing process (back-end process) wire bonding
Molding
Semiconductor manufacturing process (back-end process) molding

Post-process processing and Matsudate technology

  • Dicing: Very high precision is required for wafer cutting. In dicing equipment, Matsusada Precision's high-performance high-voltage power supply is also useful for high-precision wafer cutting. In plasma dicing, an electrostatic chuck is used to fix the wafer, and the high-voltage power supply for the Seiden chuck is useful.

  • Wire bonding: Lead-frames that are bonded to chips by wire bonding are electroplated. This is to improve the bonding between the wire and the frame. In electroplating, the metal to be plated is immersed in a plating solution and electricity is applied to deposit the metal in the solution on the surface of the metal to be plated. Matsusada Precision provides power supplies used for electroplating of leadframes.

  • Evaluation testing: The pre-shipment inspection process for semiconductor products includes dielectric breakdown testing, electrostatic discharge testing, and X-ray non-destructive testing. In a dielectric breakdown test, a high voltage is applied to the insulator or other material covering the semiconductor, and the amount of voltage at which it is destroyed is measured.

    The electrostatic discharge test is also a test to evaluate the durability of the product when electrostatic discharge occurs when a person touches it. In the static discharge test, the capacitor is charged with a voltage and given a fast pulse current. Matsusada Precision provides high-voltage power supplies used for dielectric breakdown testing and electrostatic discharge testing.

    X-ray non-destructive inspection is an inspection in which an object is irradiated with X-rays to check its internal state.Matsusada Precision offers a line of X-ray transmission inspection systems that you can use for X-ray nondestructive inspection of semiconductors.

Recommended products

Matsusada Precision's products meet the stringent specifications required by semiconductor manufacturing processes and are used throughout the fab.