KR20110014051A

KR20110014051A - Manufacturing method of 3-axis accelerometer

Info

Publication number: KR20110014051A
Application number: KR1020090071813A
Authority: KR
Inventors: 정은수
Original assignee: 주식회사 동부하이텍
Priority date: 2009-08-04
Filing date: 2009-08-04
Publication date: 2011-02-10

Abstract

The present invention relates to a manufacturing method of a three-axis accelerometer, and more particularly, to a manufacturing method of a three-axis accelerometer that can simultaneously implement the X-axis, Y-axis, Z-axis elements with a minimum area.

A method of manufacturing a triaxial accelerometer includes: a first step of forming a plurality of first trenches by performing a first etching process after TEOS deposition on an upper portion of a wafer; A second step of performing a second etching process after depositing a photoresist only between portions of the trenches where a Z-axis element is to be formed; A third step of removing the TEOS in the lower portion of the trench through the TEOS etching process after the deposition of TEOS and further etching the lower portion of the first trench by performing a third etching process; Forming a first cavity in a lower portion of the first trench by wet etching; Performing a fourth etching process to form a second trench formed in a direction perpendicular to the first trench below the first cavity; A sixth step of removing the TEOS under the trench through the TEOS etching process after the TEOS deposition and performing a fifth etching process; A seventh step of forming a second cavity in the lower portion of the trench by wet etching; And an eighth step of removing and capping the TEOS.

Accelerometer, 3 Axis, Wafer, Etch, Trench, Cavity

Description

Manufacturing method of 3-axis accelerometer

An accelerometer is a device that measures the acceleration of a moving object. Accelerometers are increasingly being used with MEMS (Micro-Electro Mechanical System) accelerometers in accordance with the demand for miniaturization and weight reduction in conventional mechanical (pendulum, ball, etc.) accelerometers. Accelerometers and tachometers, especially used in automotive parts, are being replaced by MEME parts due to fuel savings and signal accuracy. However, accelerometers used for aerospace / military use require smaller size and lighter weight. However, most MEMS inertial sensors use capacitive elements. Since a large area is required, a comb type design is widely used.

1 is a conceptual diagram of a conventional MEMS triaxial accelerometer. As shown in FIG. 1, the conventional MEMS triaxial accelerometer 1 is comprised of three elements which measure the acceleration of the X-axis 2, the Y-axis 3, and the Z-axis 3. As shown in FIG.

Capacitive MEMS accelerometers have a larger capacitance difference, simplifying the structure of the ASIC, and being more resistant to white noise, which makes signal processing easier when the device's sensitivity is improved. Accordingly, an object of the present invention is to provide a method for manufacturing a three-axis accelerometer that can simultaneously implement the X-axis, Y-axis, Z-axis component with a minimum area.

According to another preferred feature of the present invention, the pot resist in the second step is deposited in the second trenches from the left and the right, respectively.

According to another preferred feature of the present invention, the first to fourth etching process and the TEOS etching process is a reactive ion etching process.

The accelerometer manufactured by the present invention has an advantage that the X-axis, the Y-axis, and the Z-axis can be simultaneously implemented while having a minimum area as compared with the conventional accelerometer.

Hereinafter, the configuration and operation of an embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the following examples are provided to enable those skilled in the art to fully understand the present invention, but the scope of the present invention is not limited by the embodiments described below.

2 to 15 are views showing the manufacturing process of the three-axis accelerometer according to the present invention. Hereinafter, the present invention will be described in detail with reference to FIGS. 2 to 15.

The first step is to form a plurality of first trenches by performing a first etching process after the TEOS deposition on the wafer. 2 and 3, after depositing a plurality of TEOS (Tetra Ethyl Ortho Silicate) on the wafer 10 to form the TEOS layer 11, the photoresist 12 is coated and the first etching process is performed. Proceeding to form a plurality of first trenches 21. Here, the etching mask layer 12 is patterned to form the first trench 21 to form a shape as shown in FIG. 2, and then the etching mask layer 12 is etched to a predetermined depth of the wafer 10 using the etching mask layer 12. Form the same as 3. Here, the plurality of first trenches 21 is not limited in number, and may be set differently depending on what purpose to use.

The second step is a step of performing a second etching process after depositing a photoresist only between portions of the first trenches 21 where the Z-axis element is to be formed. In this case, the photoresist 15 is deposited only on the trenches 21a and 21b between the portions where the Z-axis element is to be formed, and then the second etching process is performed so that only this portion is not etched. Thus photoresist is deposited in the second trench from the left and the second trench from the right, respectively. 4 is a shape after the photoresist 15 is deposited only between the portions where the Z-axis element is to be formed, FIG. 5 is a shape after the second etching process is performed, and FIG. 6 is after the photoresist 15 is removed. Shape. As shown in FIGS. 5 and 6, some of the first trenches are additionally etched through the second etching process to become deep first trenches.

The third step is to remove the TEOS in the lower portion of the trench through the TEOS etching process after the TEOS deposition, and to further etch the lower portion of the first trench by performing the third etching process. As shown in FIG. 7, first, the TEOS is deposited on the wafer and then the TEOS is etched again to remove the TEOS under the first trench 21. Next, the third etching process is performed to further etch the lower portion of the first trench 21 to form a shape as shown in FIG. 8.

The fourth step is to form a first cavity in the lower portion of the first trench by wet etching. Since the TEOS layer is not formed on the sidewall of the portion 23 additionally etched in the third etching process, the cavity 24 is formed in the lower portion of the first trench as shown in FIG. 9 during the wet etching process.

In the fifth step, a fourth etching process is performed to form a second trench formed in a direction perpendicular to the first trench below the first cavity. As shown in FIG. 10, the fourth etching process is performed to form a second trench 25 in the lower portion of the first cavity 24. The second trench 25 is formed in a direction perpendicular to the first trench 21.

The sixth step is a step of removing the TEOS under the trench through the TEOS etching process after the TEOS deposition, and proceeds to the fifth etching process. As shown in FIG. 11, after the TEOS layer 13 is formed, the lower TEOS layer is removed, and a fifth etching process is performed to have a shape as shown in FIG. 12.

The seventh step is to form a second cavity in the lower portion of the trench by wet etching. As shown in FIG. 13, the second cavity 27 is formed by performing wet etching on a portion where the TEOS layer is not formed in FIG. 12.

The eighth step is to remove and cap TEOS. After completely removing the TEOS as shown in FIG. 14, the metal capping process is performed by bonding to complete the triaxial accelerometer as shown in FIG. 15.

Here, reference numeral 30 denotes a fixed beam, reference numeral 31 denotes a Z-axis element, and reference numeral 33 denotes a X Y-axis element.

Meanwhile, in the present invention, since the first etching process and the fourth etching process and the TEOS etching process should be etched only in the vertical direction, it is preferable to use a reactive ion etching process.

In addition, the wet etching, it is preferable to use the tetramethylammonium hydroxide (TMAH) in consideration of the efficiency of the process.

1 is a conceptual diagram of a conventional MEMS three-axis accelerometer,

2 to 15 are views showing the manufacturing process of the three-axis accelerometer according to the present invention.

10: wafer

21: trench

24,27: Cavity

Claims

A first step of forming a plurality of first trenches by performing a first etching process after TEOS deposition on the wafer;

A second step of performing a second etching process after depositing a photoresist only between portions of the trenches where a Z-axis element is to be formed;

A third step of removing the TEOS in the lower portion of the trench through the TEOS etching process after the deposition of TEOS and further etching the lower portion of the first trench by performing a third etching process;

Forming a first cavity in a lower portion of the first trench by wet etching;

Performing a fourth etching process to form a second trench formed in a direction perpendicular to the first trench below the first cavity;

A sixth step of removing the TEOS under the trench through the TEOS etching process after the TEOS deposition and performing a fifth etching process;

A seventh step of forming a second cavity in the lower portion of the trench by wet etching;

And an eighth step of removing and capping the TEOS.

The method of claim 1, wherein the pot resist in the second step is deposited in the second trenches from the left side and the right side, respectively.

The method of claim 1, wherein the first to fourth etching processes and the TEOS etching process are reactive ion etching processes.