CN102169038A - Side wall protection method for MEMS (Micro Electronic Mechanical System) silicon capacitive pressure transducer with sandwich structure - Google Patents

Abstract

The invention provides a method for protecting the side wall of a MEMS capacitive pressure sensor with a glass-silicon-glass or silicon-silicon-glass sandwich structure, which prevents dust and water from polluting the capacitor gap during the sensor manufacturing process. It is characterized in that in the manufacturing process of the MEMS capacitive pressure sensor, an auxiliary side wall is introduced before the air guide hole to prevent dust and water from entering the capacitance gap during the process, and a silicon nitride film is set between the auxiliary side wall and the bottom glass. Prevent the auxiliary sidewall from bonding with the bottom glass, so that after the chip is separated, the sidewall is automatically separated from the chip. Advantages: Due to the introduction of the auxiliary side wall before the air guide hole, it effectively prevents dust and water from entering the capacitor gap during the process, and because a silicon nitride film is set between the auxiliary side wall and the bottom glass, it prevents the auxiliary side wall from being connected to the bottom glass. Bonding, so that after the chip is separated, the sidewall is automatically separated from the chip. Improve the reliability and yield of silicon capacitive pressure sensors.

Description

Side wall protection method for sandwich structure MEMS silicon capacitive pressure sensor

technical field

The invention relates to a method for protecting the side wall of a MEMS capacitive pressure sensor with a glass-silicon-glass or silicon-silicon-glass sandwich structure. Specifically, it is a process method for preventing dust and water from polluting the capacitor gap during the manufacturing process of the sandwich structure MEMS capacitive pressure sensor. The invention belongs to the technical field of MEMS capacitive pressure sensor production.

Background technique

Dust and water in the manufacturing process of the sandwich structure silicon MEMS capacitive pressure sensor composed of glass-silicon-glass or silicon-silicon-glass three-layer structure are the main factors affecting the reliability and yield of the sensor. Dust and water during the process will enter the capacitor gap through the air guide hole, and the dust and water entering the capacitor gap are difficult to remove after the process is completed. This further affects the reliability and yield of the silicon capacitive pressure sensor.

Contents of the invention

The invention proposes a method for protecting the side wall of a MEMS capacitive pressure sensor with a glass-silicon-glass or silicon-silicon-glass sandwich structure. Its purpose is to prevent dust and water from entering the capacitance gap during the manufacturing process of glass-silicon-glass or silicon-silicon-glass three-layer silicon capacitive pressure sensor.

The technical solution of the present invention: it is characterized in that in the manufacturing process of the MEMS capacitive pressure sensor, an auxiliary side wall is introduced before the air guide hole to prevent dust and water from entering the capacitance gap during the process, and the auxiliary side wall and the bottom glass A silicon nitride film is arranged between them to prevent the auxiliary sidewall from bonding with the underlying glass, so that the sidewall is automatically detached from the chip after the chip is separated.

The advantages of the present invention: the introduction of the auxiliary side wall before the air guide hole effectively prevents dust and water from entering the capacitance gap during the process, and the installation of a silicon nitride film between the auxiliary side wall and the bottom glass prevents the auxiliary side wall Bonded to the underlying glass so that the sidewalls are automatically detached from the chip after the chip is separated. Therefore, the reliability and yield of the silicon capacitive pressure sensor are improved.

Description of drawings

Fig. 1 is a front sectional view of a silicon capacitive pressure sensor before the side wall is separated from the chip.

Fig. 2 is a cross-sectional view of the silicon capacitive pressure sensor after the side wall is separated from the chip.

Figure 3 is a schematic diagram of the bottom glass and its upper electrode.

FIG. 4 is a schematic diagram of the bottom surface of the silicon structure and the cavity on the bottom surface.

FIG. 5 is a schematic diagram of the top surface and the top cavity of the silicon structure.

Fig. 6 is a schematic diagram of a three-layer structure.

1 in the figure is the top layer of glass, 2 is the sensitive silicon membrane structure of the capacitive pressure sensor, 3 is the bottom glass, 4 is the electrode and pressure pad of the capacitor, 5 is the silicon nitride membrane structure, 6 is the vacuum cavity, 7 Is the capacitor gap, 8 is the air hole, and 9 is the silicon auxiliary side wall.

Detailed ways

With reference to accompanying drawing 1, its structure is the top glass 6 between the top glass 1 and the sensitive silicon membrane structure 2 of the capacitive pressure sensor, on the bottom glass 3 is the electrode of the capacitor and the pressure pad 4, before the air guide hole 8 is the introduced silicon A silicon nitride film structure 5 is arranged between the auxiliary side wall 9 and the silicon auxiliary side wall 9 and the bottom glass 3 , and a capacitive gap 7 is formed between the sensitive silicon film structure 2 and the silicon nitride film structure 5 of the capacitive pressure sensor.

In the manufacturing process of glass-silicon-glass or silicon-silicon-glass three-layer MEMS capacitive pressure sensor, a silicon auxiliary side wall 9 is introduced before the air guide hole 8 to prevent dust and water from entering the capacitance gap 7 during the process, A silicon nitride film structure 5 is arranged between the silicon auxiliary sidewall 9 and the bottom glass 3 to prevent the bonding of the silicon auxiliary sidewall 9 and the bottom glass 3, so that after the chip is separated, the silicon auxiliary sidewall 9 is automatically separated from the chip (as shown in Figure 2 ).

Referring to Figure 3, in the process of making the bottom glass and its upper electrode, a silicon nitride film structure 5 is made to prevent bonding between the silicon auxiliary sidewall 9 and the bottom glass 3 during the anodic bonding process;

Referring to accompanying drawing 4, in the process of making silicon structure, utilize ICP or wet etching process, make silicon auxiliary sidewall 9 on the bottom surface of sensitive silicon film structure 2 of capacitive pressure sensor, be used to prevent in process, dust or Water pollution to the capacitor gap 7; after the bonding process is completed, the wafer is diced. During the scribing process, the scribing depth is controlled, and the structure of the silicon auxiliary sidewall 9 is maintained, as shown in FIG. 1 , so that the silicon auxiliary sidewall 9 continues to prevent dust and water from entering the capacitor gap 7 during the scribing process. After the dicing is completed, when the wafer is split and the chip is separated, since the silicon auxiliary sidewall 9 is not bonded to the bottom glass 3, the silicon auxiliary sidewall 9 is automatically separated from the chip under the stress of chip splitting, as shown in the figure 2. As shown in Figure 6, realize the communication between the air guide hole and the external air.

Glass-silicon-glass or silicon-silicon-glass three-layer structure silicon MEMS capacitive pressure sensor is a pressure sensor structure with high precision, good sensitivity and good long-term stability, mainly through wet and dry etching process, metallization process , Glass-silicon-glass or silicon-silicon-glass three-layer bonding process, which has the advantages of simple process and easy realization in the process, and is widely used in meteorology, vacuum gauges, altimeters and other fields.

Claims (1)

1. A MEMS capacitive pressure sensor side wall protection method for glass-silicon-glass or silicon-silicon-glass sandwich structure, characterized in that the MEMS capacitance of glass-silicon-glass or silicon-silicon-glass sandwich structure During the production process of the pressure sensor, an auxiliary side wall is introduced before the air guide hole to prevent dust and water from entering the capacitance gap. A silicon nitride film is set between the auxiliary side wall and the bottom glass to prevent the auxiliary side wall from bonding with the bottom glass. After the chip is separated, the side wall is automatically separated from the chip.

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