CN209835625U

CN209835625U - MEMS device

Info

Publication number: CN209835625U
Application number: CN201822248710.2U
Authority: CN
Inventors: 孙伟; 闻永祥; 刘琛; 张旭
Original assignee: Hangzhou Silan Microelectronics Co Ltd; Hangzhou Silan Integrated Circuit Co Ltd
Current assignee: Hangzhou Silan Microelectronics Co Ltd; Hangzhou Silan Integrated Circuit Co Ltd
Priority date: 2018-12-29
Filing date: 2018-12-29
Publication date: 2019-12-24
Anticipated expiration: 2028-12-29

Abstract

The application discloses a MEMS device. The MEMS device includes: forming a stop layer on a substrate; forming a structural layer on the stop layer; and patterning the structural layer to form an opening with an inclined side wall, wherein the thickness of the structural layer is greater than or equal to a preset value, and the step of forming the structural layer comprises the following steps: and sequentially depositing multiple layers of silicon dioxide on the stop layer by using a plasma enhanced chemical vapor deposition method, so that the MEMS device has enough sensitivity to receive a magnetic signal. The utility model has the advantages that: an opening with an inclined side wall is manufactured in the thick structural layer, the inclined side wall is straight, the inclination angle is 30-60 degrees, and conditions are provided for manufacturing other structures on the inclined side wall.

Description

MEMS device

Technical Field

The present disclosure relates to the field of semiconductor technology, and more particularly, to a MEMS device.

Background

Micro-Electro-Mechanical systems (MEMS) are Micro integrated systems that use integrated circuit fabrication and micromachining techniques to fabricate Micro-structures, Micro-sensors, Micro-actuators, control and processing circuits, and even interface circuits, communication circuits, and power supplies on one or more chips. The advent of micro-electromechanical systems has enabled the concept of chips far beyond integrated circuits for the purpose of processing electrical signals, and the functionality of micro-electromechanical systems has been extended to the fields of mechanics, optics, heat, electricity, chemistry, biology, and the like. Compared with the traditional electromechanical system, the micro electromechanical system realizes the miniaturization, the intellectualization and the integration of an information system, improves the performance and reduces the power consumption and the cost.

Silicon dioxide is a thin film material of great importance in both integrated circuits and microelectromechanical systems, having excellent insulating and isolating properties. In integrated circuits, they are often used as insulating or protective layers. In the micro-electro-mechanical system, silicon dioxide can also be used as a sacrificial layer material and an isolation dielectric layer. The patterning of the silicon dioxide film is generally realized by adopting the process flows of film deposition, photoetching and etching. There are many deposition methods, and chemical vapor deposition and thermal oxidation are more common methods, and silicon dioxide films with different densities and thicknesses can be prepared according to requirements. And patterning the deposited silicon dioxide film by adopting photoetching and etching processes, wherein photoetching is responsible for pattern transfer, and etching is carried out to form a final pattern on the silicon dioxide film. The etching of the silicon dioxide is typically accomplished using a dry etch. The dry etching technology removes the etching film by a method combining physical action and chemical action, and the formed side wall has a steep appearance and a side wall angle of 80-90 degrees usually because of high etching speed and high anisotropy.

In a micro-electro-mechanical system, other structures are often required to be manufactured on the side wall of silicon dioxide, so that the inclination angle of the side wall of the silicon dioxide is required to be made as small as possible, and the side wall angle is required to be about 30-60 degrees so as to manufacture other structures on the side wall. However, dry-etched silicon dioxide cannot reduce the sidewall angle to 30 ° to 60 ° because of its high anisotropy. In the industry, a method of baking at a high temperature of about 200 ℃ is adopted to heat the mask photoresist to incline the side wall of the photoresist, and then a silicon dioxide structure with a side wall angle of about 50 degrees is prepared by dry etching. However, this method requires a special high temperature oven and baking the photoresist to be thinned to about 0.5 μm, and the thickness of the silicon dioxide with inclined sidewall is generally less than 2 μm, which cannot make the thickness of the silicon dioxide inclined sidewall structure reach 5 μm or more.

SUMMERY OF THE UTILITY MODEL

In view of the above, an object of the present invention is to provide a MEMS device, which has an opening with an inclined sidewall formed in a thick structure layer, and provides conditions for forming other structures on the inclined sidewall.

According to an aspect of the present invention, there is provided a MEMS device, including: a substrate; a stop layer on the substrate; a structural layer on the stop layer having an opening with an inclined sidewall; wherein the thickness of structural layer is more than or equal to the default, the structural layer includes: a plurality of layers of silicon dioxide sequentially deposited on the stop layer.

Preferably, the thickness of each layer of the silicon dioxide is equal, and the structural layer is a sparse layer.

Preferably, the number of layers of the multilayer silica comprises 2-7 layers, and the thickness of each layer of the silica comprises 1-2 μm.

Preferably, the thickness of the stop layer ranges from 500 to

Preferably, wherein the inclination angle of the inclined sidewall comprises 30 ° to 60 °.

Preferably, the gradient distribution of the structural layer density is set according to the inclination angle of the inclined side wall.

Preferably, the inclined side wall is straight.

Preferably, the preset value is 5 microns.

According to the utility model provides a MEMS device produces the opening that has the slope lateral wall in thick structural layer, and the slope lateral wall is straight form, and inclination provides the condition for making other structures on the slope lateral wall between 30 to 60 degrees, compares with prior art:

the utility model discloses used the PECVD method to make thick structural layer (more than 5 um), not used the thermal oxidation method of current boiler tube to grow, and then utilized photoetching and wet corrosion equipment to make the slope lateral wall that is less than current 80-90 inclination on the structural layer for it is possible to make the picture on the thick structural layer lateral wall in micro-electromechanical system, if geomagnetic sensor Z axle direction need make the magnetic resistance layer at the lateral wall, makes the MEMS device have sufficient sensitivity in order to receive the magnetic signal;

after an opening is formed on the structural layer, the photoresist is conventionally baked to be cured so as to avoid falling off, a high-temperature oven with the temperature of 200 ℃ is not required to be additionally prepared, and the operation is simple and efficient;

simultaneously, only rely on technological parameters such as adjustment thermal oxidation growth, corruption just can obtain the structural layer that has straight slope lateral wall, saved the cost, moreover the utility model provides a manufacturing approach is very simple and direct, can regard as the technological means of volume production.

Furthermore, the utility model discloses a MEMS device sets up the gradient distribution of the density of structural layer according to the inclination of slope lateral wall has been controlled more accurately.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

fig. 1 shows a schematic cross-sectional view of a MEMS device of an embodiment of the invention;

fig. 2 shows a flow chart of a method of manufacturing a MEMS device of an embodiment of the invention;

fig. 3-7 show cross-sectional schematic views of the MEMS device of fig. 2 during fabrication.

Detailed Description

The invention will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by like reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale. In addition, certain well known components may not be shown.

Numerous specific details of the invention, such as structure, materials, dimensions, processing techniques and techniques of the devices are described below in order to provide a more thorough understanding of the invention. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details.

The present invention may be presented in a variety of forms, some of which are described below.

Fig. 1 shows a schematic cross-sectional view of a MEMS device according to an embodiment of the invention.

As shown in fig. 1, the MEMS device of the embodiment of the present invention includes: the MEMS device comprises a substrate 100, a stop layer 110 and a structural layer 120, wherein the structural layer 120 has an opening 121, and the thickness of the structural layer 120 is greater than or equal to a preset value, and the preset value is preferably 5 μm, so that the MEMS device has enough sensitivity to receive a magnetic signal.

Substrate 100 is a semiconductor material, substrate 100 may be a non-patterned polished wafer or a patterned wafer having completed a circuit die passivation process, and in some preferred embodiments, substrate 100 further includes a structural layer step.

A stop layer 110 is disposed on the substrate 100, the stop layer 110 is made of silicon nitride, and the thickness of the stop layer 110 ranges from 500 a to 500 aIn some preferred embodiments, the stop layer 110 has a thickness of

The structural layer 120 is located on the stop layer 110, the material of the structural layer 120 includes silicon dioxide, in this embodiment, the structural layer 120 is composed of multiple layers of silicon dioxide, the structural layer is a sparse layer with a smaller density, wherein the thickness of each layer of silicon dioxide is the same, so that the concentration of silicon dioxide is more uniform, the number of layers of silicon dioxide includes 2-7 layers, the thickness range of each layer includes 1-2 μm, in some preferred embodiments, the number of layers of silicon dioxide is 5 layers, and the thickness of each layer of silicon dioxide is 1 μm. Opening 121 on structural layer 120 has the slope lateral wall, and this slope lateral wall is straight form, and inclination includes 30 to 60, and in some preferred embodiments, inclination is 50, and further, the MEMS device of the embodiment of the present invention can set up the gradient distribution of the density of structural layer 120 according to the inclination of slope lateral wall.

Fig. 2 shows a flow chart of a method for manufacturing a MEMS device according to an embodiment of the present invention, and fig. 3 to 7 show schematic cross-sectional views of the MEMS device of fig. 2 during a manufacturing process.

Hereinafter, fig. 2 will be described in detail with reference to fig. 3 to 7.

In step S01, a substrate is provided. Specifically, as shown in fig. 3, the substrate 100 is cleaned by using the RCA standard cleaning process, the substrate 100 is a semiconductor material, the substrate 100 may be a non-patterned polished wafer or a patterned wafer in which a circuit and a MEMS monolithic chip are integrated on the same die and a circuit passivation layer process is completed, and in some preferred embodiments, the substrate 100 further includes a structural layer step.

In step S02, a stop layer is formed on the substrate. Specifically, as shown in fig. 4, a stop layer 110 is formed on a substrate 100 by using a Plasma Enhanced Chemical Vapor Deposition (PECVD), and a thickness of the stop layer 110 ranges from 500 a to 500 aIn some preferred embodiments, the stop layer 110 has a thickness ofAt this thickness, the stop layer 110 can resist the corrosion of HF in the subsequent steps, keeping the depth of the sloped sidewall structure unchanged while protecting the pattern under the stop layer 110.

The process gases required in this step include: monosilane SiH4, laughing gas and nitrogen, the temperature for forming the stop layer 110 is less than or equal to 450 ℃.

In step S03, a structural layer is formed on the stop layer. Specifically, as shown in fig. 5, forming the structural layer 120 on the stop layer 110 by PECVD steps requires sequentially depositing 5 layers of silicon dioxide on the substrate 100, each layer of silicon dioxide having a thickness of 1 μm, the process gases required in this step include: monosilane SiH₄Laughing gas and nitrogen, and the temperature during deposition is less than or equal to 400 ℃. Wherein, the utility model discloses MEMS device can set up the gradient distribution of the density of structural layer 120 according to the inclination of slope lateral wall, adopts PECVD growth silicon dioxide, and its speed is far greater than the growth of thermoxidation, adopts PECVD's method preparation structural layer 120 to have the less loose and not compact characteristics of density, and in follow-up corrosion step, the speed that loose not compact structural layer 120 is corroded is fast, can form the slope lateral wall.

In step S04, a photoresist is coated on the structural layer and an etch window is formed. Specifically, as shown in fig. 6, a positive photoresist 130 is coated on the structural layer 120, the photoresist 130 is exposed by a conventional stepper, and an etching window 131 is formed by two-time development. Wherein the thickness of the photoresist 130 ranges from 2 to 5 μm, and in some preferred embodiments, the thickness of the photoresist 130 is 3 μm.

In step S05, the remaining photoresist at the etch window is removed. Specifically, as shown in FIG. 6, the remaining photoresist 130 at the etching window 131 is removed, the process time of this step is 5 to 15min to ensure that no photoresist 130 is present at the etching window 131, the power used comprises 50 to 350W, and the thickness of the removed photoresist 130 is about 500 to 350W

In step S06, the photoresist is baked. Specifically, as shown in fig. 6, the photoresist 130 is conventionally baked to cure the photoresist 130, so as to ensure that the photoresist 130 does not fall off in the subsequent steps, wherein the baking temperature includes 80 ℃ to 120 ℃, the baking time includes 15 to 60min, and in some preferred embodiments, the baking temperature is 120 ℃, and the baking time is 30 min.

In step S07, an opening having sloped sidewalls is formed in the structural layer. Specifically, as shown in fig. 7, the structure layer 120 is etched by an isotropic etching method using a wet etching solution, and the etching is stopped when the etching reaches the stop layer 110. Since the density of the structural layer 120 is graded in the longitudinal direction, the closer to the stop layer 110 the greater the density and vice versa, the more sparsely dense structural layer 120 erodes at a greater rate, thereby forming an opening in the structural layer 120 having sloped sidewalls that are straight, at an angle of inclination that includes 30 to 60 °, and in some preferred embodiments, 50 °. The wet etching solution comprises the following components: water, ammonium fluoride and hydrofluoric acid, water: ammonium fluoride: the proportion of hydrofluoric acid ranges from 10:4:1 to 10:6:1, preferably 10:5:1, and at this proportion, the concentration of hydrofluoric acid is moderate, and the problem that the concentration of hydrofluoric acid is too small, so that the side wall is not straight, and the lateral corrosion of the side wall is not controlled due to too large concentration, so that the formed side wall is unstable is solved. The process time for forming the opening, i.e., the etching time, is greater than or equal to 5min to ensure that the rounded corners of the top of the structural layer 120 are etched, and the process temperature for forming the opening ranges from room temperature to 50 ℃, and in some preferred embodiments, the process temperature for this step is 40 ℃. Further, other structures, such as a magnetoresistive layer, may be fabricated on the sloped sidewalls. The wet etching process method forms an inclination angle of 30-60 degrees, and effectively solves the problem that the inclination angle is too large due to the process limitation in the prior art, so that a structural layer is difficult to manufacture on the inclined side wall.

In step S08, the photoresist is removed by a dry wet method to form the MEMS device as shown in fig. 1.

According to the utility model provides a MEMS device and manufacturing method thereof produces the opening that has the slope lateral wall in the structural layer, and the slope lateral wall is straight form, and inclination is between 30 to 60 degrees, for making other structures on the slope lateral wall and provide the condition, compare with prior art, the utility model discloses only used conventional PECVD, photoetching and wet etching equipment, need not additionally prepare 200 ℃ high temperature oven, simultaneously, only rely on technological parameters such as adjustment thermoxidation growth, corruption just can obtain the structural layer that has straight slope lateral wall, saved the cost, moreover the utility model provides a manufacturing method is very simple and direct, can regard as the technological means of volume production.

Furthermore, the utility model discloses MEMS device and manufacturing method thereof sets up the gradient distribution of the density of structural layer according to the inclination of slope lateral wall has been controlled more accurately.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

In accordance with the embodiments of the present invention as set forth above, these embodiments are not exhaustive and do not limit the invention to the precise embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and its various embodiments with various modifications as are suited to the particular use contemplated. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A MEMS device, comprising:

a substrate;

a stop layer on the substrate;

a structural layer on the stop layer having an opening with an inclined sidewall;

wherein the thickness of structural layer is more than or equal to the default, the structural layer includes: a plurality of layers of silicon dioxide sequentially deposited on the stop layer.

2. The MEMS device of claim 1, each layer of the silicon dioxide being of equal thickness, the structural layer being a sparse layer.

3. The MEMS device of claim 2, wherein the number of layers of the multilayer silicon dioxide comprises 2-7 layers, each layer of the silicon dioxide comprising a thickness of 1-2 μ ι η.

4. The MEMS device of claim 3, wherein the stop layer has a thickness ranging from 500 a to

5. The MEMS device of any of claims 1 to 4, wherein the angle of inclination of the sloped sidewalls comprises 30 ° to 60 °.

6. The MEMS device of claim 5, wherein the gradient distribution of the structural layer density is set according to an inclination angle of the inclined sidewall.

7. The MEMS device of claim 6, wherein the sloped sidewalls are straight.

8. The MEMS device of any of claims 1-4, wherein the preset value is 5 microns.