KR19980048730A - Manufacturing Method of Semiconductor Acceleration Sensor - Google Patents

Abstract

The present invention relates to a method of manufacturing a semiconductor acceleration sensor, and more particularly to manufacturing a semiconductor acceleration sensor that can form a beam by wet etching without using a RIE process using aluminum, nickel-chromium, gold as a metal layer. It is about a method.

To this end, the present invention is a method of manufacturing a semiconductor acceleration sensor for sensing the acceleration applied from the outside by the resistance value change of the piezoresistor according to the flow of the mass formed on the silicon wafer,

Depositing aluminum (4) on the piezoresistor (3), patterning the aluminum layer (4) in a predetermined form, and sequentially forming a nickel-chromium layer (6) and a gold layer (7) on the patterned aluminum layer. Depositing the nickel-chromium / gold layer on the deposited nickel-chromium / gold layer with a wiring pattern larger than the aluminum pattern so as to completely cover the patterned aluminum layer; and tetramethylammoniumhydroxide (TMAH), which is a silicon etching solution. Etching a portion of the silicon wafer by a solution to form a beam 30 supporting the mass 20.

Description

Manufacturing Method of Semiconductor Acceleration Sensor

The present invention relates to a method for manufacturing a semiconductor acceleration sensor, and more particularly, aluminum (Al), nickel (Ni) -chromium (Cr) and gold (Au) as a metal layer does not perform a complex process such as RIE process The present invention relates to a method for manufacturing a semiconductor acceleration sensor that can form the same structure by simple wet etching.

A semiconductor acceleration sensor generally used is a piezoresistor 3 formed on a silicon substrate 1 through a predetermined semiconductor manufacturing process as shown in the plan view shown in FIG. 1 and whose resistance value is changed by acceleration; A metal layer serving as an electric conductor and a mass 20 converting the acceleration applied from the outside into a force and transmitting the same to the beam 30 are formed.

The manufacturing process of the conventional semiconductor acceleration sensor having such a structure is as shown in FIG. 2, and first, as shown in FIG. 2A, the silicon oxide film 2 is grown on the upper surface of the silicon substrate 1. An appropriate portion of the silicon oxide film 2 is etched to form a piezoresistor. In the next (b), a piezoresistor 3 is formed in the etched portion of the silicon oxide film 2 by ion implantation in which the resistance value changes with respect to the stress of the beam caused by the acceleration.

Thereafter, as shown in (c), aluminum (Al) serving as a conductive wire is deposited on the portion where the piezoresistor 3 is formed, and then, as shown in (d), the aluminum on the upper surface is etched by the etching solution. As a protective film 5 to prevent etching, a photoresist (PR) or silicon oxide film having a predetermined pattern is formed on the aluminum layer 4.

In the next step (e), the silicon is etched through the upper and lower portions except for the beam of the silicon substrate by a reactive ion etching (RIE) process, and in (f), the photoresist film formed of the protective film 5 of the metal layer is finally formed. Alternatively, the silicon oxide film is removed to complete the structure of the semiconductor acceleration sensor.

However, in the conventional manufacturing method, after forming a metal layer such as aluminum, the RIE process must be performed to etch the silicon layer for beam formation, and at this time, a protective film must be formed to protect the aluminum during the RIE process. There was a hassle to pattern.

On the other hand, as a general silicon etching solution, a lot of KOH solution is used, but the most widely used metal material aluminum (Al) can not withstand the KOH solution, RIE process using expensive equipment was inevitable.

Accordingly, in the present invention, a method of manufacturing a semiconductor accelerometer sensor which is capable of simply wet etching without performing an RIE process while protecting an aluminum layer from a silicon etchant during etching a silicon layer for beam formation. Is to provide.

1 is a plan view of a conventional semiconductor acceleration sensor,

2 is a view showing a method of manufacturing a conventional semiconductor acceleration sensor;

3 is a view showing a method of manufacturing a semiconductor acceleration sensor according to the present invention.

Explanation of symbols on the main parts of the drawings

Silicon substrate, silicon oxide film,

3 ... piezoresistive, 4 ... aluminum (Al),

5 ... shield, 6 ... nickel (Ni) -chromium (Cr),

7 ... Au, 20 ... mass,

30 ... beam.

In order to achieve the above object, the method for manufacturing a semiconductor acceleration sensor according to the present invention is a method for manufacturing a semiconductor acceleration sensor for sensing acceleration applied from the outside by a change in resistance value of a piezoresistor according to the flow of mass formed on a silicon wafer. ,

Depositing aluminum on the piezoresistor, patterning the aluminum layer in a predetermined form, depositing nickel-chromium and gold sequentially on the patterned aluminum layer, and patterning the deposited nickel-chromium / gold layer. Patterning the nickel-chromium / gold layer with a wiring pattern larger than the aluminum pattern so as to completely cover the aluminum layer, and etching a part of the silicon wafer by TMAH (Tetramethylammoniumhydroxide) solution, which is a silicon etching solution, to support the mass It characterized in that it comprises a step of forming.

Hereinafter, the configuration and the effect according to the preferred embodiment of the present invention will be described in detail. First, as shown in FIG. 1, the semiconductor acceleration sensor according to the present invention is formed on a silicon substrate 1 through a predetermined semiconductor manufacturing process, and has a piezoresistor 3 whose electrical resistance is changed by acceleration, and an electrical conductor wire. The aluminum metal layer and the acceleration applied from the outside is converted into a force to form a mass 20 to transmit to the beam 30.

3 shows a method of manufacturing a semiconductor acceleration sensor according to the present invention having such a configuration. In the method of manufacturing a semiconductor acceleration sensor of the present invention, as shown in FIG. 3, first, the silicon oxide film 2 is grown on the top surface of the silicon substrate 1 in the step (a), and then the silicon oxide film is formed to form a piezoresistor. The appropriate part of (2) is etched. In the next (b), a piezoresistor 3 is formed in the etched portion of the silicon oxide film 2 by ion implantation in which the resistance value changes with respect to the stress of the beam caused by the acceleration.

Thereafter, as shown in (c), aluminum 4, which serves as a conductive wire, is deposited on a portion in which the piezoresistor 3 is formed, and then a metal layer is defined by defining a pattern of the metal layer, and a silicon etching solution is formed on the patterned aluminum layer. Gold is deposited to protect aluminum from TMAH (Tetramethylammoniumhydroxide) solution.

However, in this case, in order to improve the contact resistance between gold and aluminum, nickel-chromium is deposited on aluminum as a buffer layer. That is, in (d), nickel (Ni) -chromium (Cr) / gold (Au) is added to the aluminum metal layer to prevent the aluminum on the upper surface from being etched by the etching solution before etching the silicon on the lower surface to form the beam. 4) Formed on. In this case, chromium (Cr) in the nickel (Ni) -chromium (Cr) layer is to improve the adhesion between gold (Au) and aluminum (Al), and nickel (Ni) diffuses gold (Au) into silicon. It is deposited separately to prevent entry.

In particular, the pattern of aluminum formed in the previous step when patterning the metal protective film of nickel-chromium / gold as a method for preventing the bottom portion of aluminum from being etched by the gold etchant during the gold etching process in order to pattern the gold layer in a predetermined form. Larger wiring pattern masks are used to pattern the nickel-chromium / gold layer to completely cover the aluminum layer to protect the aluminum from the gold etchant.

On the other hand, the gold (Au), unlike aluminum does not need to be corroded in the TMAH solution which is an etching solution for etching silicon well for several hours, so there is no need for a separate protective film. Therefore, when the metal masking process is completed, in step (e), the silicon substrate is made of a silicon etching solution such as a TMAH solution using a nickel (Ni) -chromium (Cr) and a gold (Au) layer as a protective material of the aluminum layer 4. The structure of the semiconductor acceleration sensor is completed by forming a beam for supporting the mass by etching the silicon in the upper and lower portions except for the beams of (1).

As such, when the acceleration sensor according to the present invention manufactured by the above method is mounted on an object, the acceleration of the object is transmitted to the sensor, and the mass of the sensor moves in proportion to the acceleration, and the beam supporting the mass is bent to a certain degree. As a result, stress is generated in the beam and the resistance value of the piezoresistor on the beam is changed. Therefore, the acceleration of the object can be determined by detecting the change in the resistance value of the piezoresistor.

As described above, the nickel (Ni) -chromium (Cr) / gold (Au) layer may be formed of aluminum (in order to protect the aluminum layer from the etching solution for etching silicon by the method of manufacturing a semiconductor acceleration sensor according to the present invention). By depositing on the Al) layer, the same structure can be obtained by a simplified process of etching silicon with a TMAH solution, which is a silicon etching solution, without going through a complicated process such as an RIE process using expensive equipment. It will provide the effect of reducing the cost burden.

In addition, after the deposition of the aluminum layer and the deposition of the metal layer protective film, respectively, by using a different wiring pattern mask to form a pattern such that the metal layer sufficiently covers the aluminum layer, it is possible to prevent damage of the aluminum layer by the fast etching solution.

Claims (1)

In the manufacturing method of the semiconductor acceleration sensor for detecting the acceleration applied from the outside by the resistance value change of the piezoresistor according to the flow of the mass formed on the silicon wafer, Depositing aluminum (4) on the piezoresistor (3), Patterning the aluminum layer 4 to a predetermined shape, Sequentially depositing a nickel-chromium layer 6 and a gold layer 7 on the patterned aluminum layer; Patterning the deposited nickel-chromium 6 and gold layer 7 into a wiring pattern larger than an aluminum pattern so as to completely cover the patterned aluminum layer; Forming a beam 30 supporting the mass 20 by etching a portion of the silicon wafer 1 with a TMAH (Tetramethylammoniumhydroxide) solution, which is a silicon etching solution. .