Back-End Semiconductor Manufacturing Process

The process of manufacturing semiconductors is similar to creating business cards.

In the case of business cards, the first step is to finalize a design, followed by printing several copies on a large sheet of paper. Finally, the printed sheet is cut to produce individual cards.

The semiconductor manufacturing process follows a similar workflow. Manufacturing is divided into design, front-end, and back-end processes. The design process corresponds to the card design, and the front-end process corresponds to printing. The subsequent step involves cutting the wafers into individual pieces.

Semiconductors undergo a design process, and large-scale integrated circuits (LSI) are created on silicon wafers during the front-end process. These integrated circuits are then cut into individual chips during the back-end process. This article discusses the back-end process.

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

In the back-end process, the semiconductor is cut from the wafer and packaged into a final product. While the front-end process creates large-scale integrated (LSI) circuits on a silicon wafer, the back-end process separates these circuits and processes them for use in electronic devices.

The key steps in back-end processing are as follows:

• Dicing: The wafer is cut with a diamond blade and separated into individual chips. During the dicing process, the wafer is attached to dicing tape. A rotating circular diamond blade separates the semiconductors while ultrapure water is sprayed to cool the blade and remove debris.

  In addition to the diamond blade method, other dicing techniques exist, such as laser dicing, the scribe method (creating cracks by scratching the surface), and plasma dicing (using plasma etching for separation).

  When dicing tape is used, the tape holding the wafer must remain intact. After cutting, the dicing tape is stretched to create clearance between the chips, facilitating their removal.

• Wire bonding: The chip is mounted onto a lead frame (die bonding). A lead frame is a thin metal structure that supports the chip and serves as the terminal for connecting the semiconductor to a circuit board.

  For power semiconductors or applications requiring high heat dissipation, chips may be mounted directly onto heat sinks. Adhesives such as silver paste are typically used for die bonding.

  Following die bonding, the wire-bonding process connects the chip to the lead frame using thin gold wires, establishing the electrical connection.

• Molding: Semiconductor chips are delicate and easily damaged by scratches, shock, dust, and magnetism. To protect them from these external factors, the chip is encased in epoxy resin. This process is called molding or packaging.

  However, recent trends toward device miniaturization have increased the demand for smaller semiconductors. One solution is the use of "bare dies"--semiconductors that are used without traditional packaging. While bare dies allow for high-density, 3D stacking on substrates, they require careful handling.

After dicing, wire bonding, and molding, semiconductor products undergo rigorous inspection before shipment.