New American semiconductor improves magnetic sensor and puts it into mass production

Magnetic sensors play an important role as key components in modern high-performance industries, automobiles, drones, and other industries. As a world-leading microelectronics and semiconductor technology company, MEMSIC Semiconductor integrates signal processing circuits and multi-axis AMR magnetic sensing units into a single chip, greatly improving the performance and stability of the product.

In the traditional multi-axis magnetic sensor manufacturing process, it is first necessary to etch the through hole connected to the sensor, deposit a thick dielectric layer, and etch to form a slope. Then the through hole is etched again to expose the underlying circuit, and the inductive magnetoresistive pattern is retained using etching technology. Finally, the sensor interconnect metal is directly deposited to connect the PVO integrated circuit and the inductive magnetoresistive pattern. In this traditional manufacturing process, the metal surface oxide in the PVO hole cannot be removed, resulting in abnormal hole contact resistance and even sensor failure.

In order to solve this problem, on June 12, 2018, MEMSIC Semiconductor filed an invention patent entitled "A single-chip single-axis or multi-axis magnetoresistive sensor and its manufacturing method" (application number: 201810597724.7), and the applicant was MEMSIC Semiconductor (Wuxi) Co., Ltd.

Figure 1 Single-chip magnetoresistive sensor production flow chart

FIG1 shows a schematic flow chart of a manufacturing method of a single-chip single-axis or multi-axis magnetoresistive sensor. First, a wafer 210 with an integrated circuit is provided, a passivation layer is formed on the upper surface of the wafer 210, and the substrate is silicon (step 110). Then, a first through hole connected to the magnetoresistive sensor is etched on the passivation layer to expose the metal connection of the integrated circuit (step 120). A thick dielectric layer of insulating material is deposited on the upper surface of the passivation layer with the first through hole (step 130). Then, the thick dielectric layer is photolithographically and etched to form a slope and a groove (step 140). The dielectric layer above the first through hole is etched to form a second through hole and expose the lower metal connection (step 150). Next, the surface of the thick dielectric layer and the metal connection are cleaned to remove the oxide on the metal surface (step 160), and a magnetic sensing thin film pattern is directly deposited (step 170). Finally, a sensor interconnection metal layer is deposited on it, and an interconnection metal layer pattern is etched to achieve electrical connection between the integrated circuit and the sensing magnetoresistive pattern (step 180).

It can be seen from the above magnetic sensor manufacturing flow chart that before depositing the magnetic sensing film, the surface of the metal connection in the second through hole is cleaned by physical or chemical methods to remove metal oxides, and the magnetic sensing film in the second through hole is retained during pattern lithography and etching after the magnetic sensing film is deposited to protect the metal in the second through hole from oxidation.

In short, this patent of MEMSIC Semiconductor provides a single-chip single-axis or multi-axis magnetoresistive sensor and its manufacturing method, which reduces the hole contact resistance of the sensor by increasing chemical or physical cleaning and covering protection of the magnetic sensing film, and achieves a better connection between the integrated circuit and the upper sensor.

It is reported that the new magnetic sensor completed by MEMSIC Semiconductor has already been mass-produced and put on the market. Its wafer-level packaging has solved the problem of special packaging process of the previous generation of products and greatly improved product performance. What new products will MEMSIC Semiconductor bring to the market in the future? Let us wait and see.