CN102633227B - Film pressure damp adjustable device for MEMS (micro-electromechanical system) inertial sensor structure - Google Patents

Abstract

A MEMS inertial sensor structure press-film adjustable damping device, mainly composed of a damping cap, a bonding substrate, a silicon dioxide layer, a silicon nitride layer, a bonding metal layer, a positive electrode of a resistor, a negative electrode of a resistor, an upper plate electrode, a lower plate Plate electrode, fixed base, silicon elastic film, concave cavity, upper plate metal layer, lower plate metal layer, upper plate metal layer lead-out line, lower plate metal layer lead-out line, ring resistor, ring resistor positive lead out Wire, ring resistor negative lead wire, 2 sets of heating ring resistors and 1 pair of electrostatic metal plates are made on the bonding substrate, which can reduce or increase the pressure film damping coefficient of the device to be adjusted by 1-2 orders of magnitude, From the realization of post-package modulation of the Q value of the MEMS sensor, the device has a compact and ingenious structure design, convenient operation, rapid response, and high adjustable precision.

Description

A MEMS inertial sensor structure pressure film damping adjustable device

technical field

The invention relates to a pressure film damping adjustable device after MEMS inertial sensor is manufactured, and belongs to the technical field of micro-electromechanical sensing.

Background technique

Sensors are the front end of signal acquisition in the current information technology and Internet of Things technology fields, and play an important role like "eyes". MEMS sensors attract the needs of the whole world with their powerful advantages of small size, micro power consumption, low cost and integration. In terms of technology, the strength of foreign countries has formed commercial products, which are used in high-tech fields such as mobile phones, automobiles, video games, remote control, intelligent buildings, automatic instruments, navigation, and guidance. However, the domestic foundation is weak and there is no industrialization, and most products rely on imports. , but it embargoes some high-performance MEMS inertial sensor products from abroad. Due to the urgent need for national defense and security, it is urgent to independently develop and develop.

The technical bottleneck of domestic MEMS sensors is mainly reflected in the relatively backward process conditions, it is difficult to guarantee the design accuracy, and the lack of packaging technology of the manufactured products cannot meet the index requirements, resulting in low reliability and poor stability of the device, which is finally reflected in the low precision. High and not durable. Therefore, under such technical conditions, for self-developed small batches of key MEMS inertial devices, such as accelerometers and gyroscopes, once the sensor packaging is completed, the characteristics have been finalized, and the indicators are unqualified and can only be scrapped, resulting in low yields and high processing costs. However, the urgent needs cannot be met under the current conditions. This technology is aimed at the fact that the product performance of MEMS inertial sensors in my country is far from the index after manufacture, and an improved device is proposed to achieve the purpose of adjusting sensor performance by adjusting the system damping, and solve the problem of sensor accuracy caused by insufficient process conditions. At the same time, it can also solve the requirement of adjusting the device performance of the same sensor due to different working environments, so as to achieve the purpose of multi-purpose of the same type.

The formation of damping runs through the entire process of device design, manufacturing and packaging, and has a great impact on the dynamic performance parameters of the device, such as response time, frequency response characteristics, sensitivity, linearity, noise, etc. With the miniaturization of the sensor, its characteristic size has reached the micron level, and the surface effect of the structure is reflected as the main mechanism factor of damping, making the effect of the surface damping force far exceed the volume force, which determines the damping characteristics of the system, so by controlling the fluid Damping is of great significance to the development of MEMS inertial devices with independent intellectual property rights to ensure the performance indicators of MEMS inertial devices and improve their design capabilities.

Contents of the invention

purpose of invention

The purpose of the present invention is to aim at the deficiencies of the background technology, and design a kind of pressure film damping adjustable device of MEMS devices, to meet the damping requirements of different MEMS devices in different working environments to the greatest extent, so that the detection data of MEMS devices is accurate and reliable .

Technical solutions

The main structure of the present invention consists of: damping cap, bonding substrate, silicon dioxide layer, silicon nitride layer, bonding metal layer, resistor positive electrode, resistor negative electrode, upper plate electrode, lower plate electrode, fixed base, silicon Composed of elastic film, cavity, upper plate metal layer, lower plate metal layer, upper plate metal layer lead-out wire, lower plate metal layer lead-out wire, ring resistor, ring resistor positive lead-out wire, ring resistor negative lead-out wire; The bonded substrate 2 is doped with giant ring resistors 21, 22, and a silicon dioxide layer 3 is deposited around the ring resistors 21, 22 and the surrounding central area, and the silicon dioxide layer 3 in the bonded substrate 2 central area A lower plate metal layer 18 is formed on the silicon layer 3, a silicon nitride layer 54 is deposited on the silicon dioxide layer 3 in the surrounding area of the bonding substrate 2, and a silicon nitride layer 54 is deposited in the lower area of the bonding substrate 2. On the layer 3, ring resistance positive poles 6, 8, ring resistance negative poles 7, 9, and lower plate electrodes 11 are made, and a bonding metal layer 5 is deposited on the silicon nitride layer 4 in the surrounding area, and the lower plate electrodes 11 and A silicon nitride layer 4 is deposited on the silicon dioxide layer 3 in the central area between the ring resistor negative electrodes 9, and an upper plate electrode 10 is deposited on the silicon nitride silicon 4. The two ends of the ring resistors 21, 22 are respectively Through the ring resistor positive lead wire 22,24, the ring resistor negative lead wire 23,25 is introduced into the ring resistor positive electrode 6,8, the ring resistor negative electrode 7,9, the lower plate metal layer 18 passes through the lower plate metal layer lead wire 19 and The lower plate electrodes 11 are connected, and the bonding metal layer 5 is airtightly bonded with a bonding cap 1. The inner side of the bonding cap 1 is processed with a cavity 14 to form a silicon elastic film 13 and an outer frame base 12. The inner wall of the cavity 14 The upper plate metal layer 15 is deposited, the bonding metal layer 16 is deposited on the lower surface of the outer frame base 12, and the cavity 14 after the bonding cap 1 and the bonding substrate 2 are firmly bonded is sealed with expansion sexual gas.

The bonding metal layers 5, 16, the upper plate metal layer 15, and the lower plate metal layer 18 have the same structural materials and are all composed of two layers of metal. A titanium layer 28, namely Ti A gold layer, that is, an Au layer is provided on top of the titanium layer 29 .

working principle

The ring-shaped resistance heating made on the bonding substrate makes the gas encapsulated in the concave cavity heated and expanded, causing the silicon elastic film to deform and bulge outward, thereby changing the distance between the device to be adjusted and the silicon elastic film, which will make the waiting The pressure film damping of the adjustable device becomes larger; the lower plate electrode fabricated on the bonded substrate and the upper plate electrode fabricated inside the concave cavity generate electrostatic force when energized, causing the silicon elastic film to deform and sag inward. Furthermore, changing the distance between the device to be adjusted and the silicon elastic film will reduce the compression film damping of the device to be adjusted.

Beneficial effect

Compared with the background technology, the present invention is obviously advanced. This device adopts an overall design, uses the bonded substrate as a carrier, and has two sets of annular resistors made on the bonded substrate, which are introduced into the bonded substrate through the lead-out wires of the resistor electrodes. On the side of the bottom, the metal electrode of the lower plate is made on the silicon dioxide insulating layer of the bonding substrate, and the metal electrode of the upper plate is made on the inner wall of the cavity, and the metal electrode of the upper plate passes through the lower plate of the fixed base. The bonding metal layer on the surface is introduced into the side of the bonding substrate. This device has a compact and ingenious structure. It changes the distance between the device under test and the silicon elastic film through the heating of two sets of ring resistors and the electrostatic attraction of a pair of upper and lower plates. The distance can reduce or increase the pressure film damping coefficient of the device to be adjusted by 1-2 orders of magnitude. It is easy to operate, responds quickly, and can be adjusted with high precision. It is an ideal adjustable damping device for MEMS devices.

Description of drawings

Figure 1 Overall structure diagram

Figure 2 Plane structure diagram of damping cap

      Figure 3 Sectional view of the A-A section line of the damping brim

      Figure 4 Stereoscopic structural view of the bonded substrate

Figure 5 Plane structure of bonded substrate

      Figure 6 Cross-sectional view of the bonded substrate along the B-B section line

      Figure 7 Cross-sectional view of the bonded substrate along the C-C section line

      Figure 8 Expansion structure diagram of the controllable damping device

      Figure 9 Shrinkage structure diagram of the controllable damping device

     Figure 10 Bonding metal layer structure diagram

As shown in the figure, the list of reference signs is as follows:

1. Damping cap, 2. Bonding substrate, 3. Silicon dioxide layer, 4. Silicon nitride layer, 5. Bonding metal layer, 6. Resistor positive pole, 7. Resistor negative pole, 8. Resistor positive pole, 9, Resistor negative electrode, 10, upper plate electrode, 11, lower plate electrode, 12, fixed base, 13, silicon elastic film, 14, concave cavity, 15, upper plate metal layer, 16, bonding metal layer, 17 , silicon dioxide layer, 18, lower plate metal layer, 19, lead-out wire of lower plate metal layer, 20, ring resistor, 21, ring resistor, 22, positive lead-out wire of ring resistor, 23, negative lead-out wire of ring resistor, 24. The lead-out wire of the positive electrode of the ring resistor, 25. The lead-out wire of the negative electrode of the ring resistor, 26. The device to be adjusted, 27. The silicon substrate layer, 28. The titanium layer, 29. The gold layer.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings:

Figure 1 shows the overall structure diagram, with a bonded substrate 2 as a carrier, on which a silicon dioxide layer 3, a silicon nitride layer 4, a bonded metal layer 5, and a bonded metal layer are deposited. 5 is bonded with a damping cap 1, and the silicon dioxide layer 3 in the lower region of the bonding substrate 2 is respectively made with ring-shaped positive electrodes 6, 8, lower plate electrodes 11, silicon nitride layer 4, and ring-shaped resistors from left to right. Resistor negative electrodes 9, 7, upper plate electrode 10 on silicon nitride layer 4 between lower plate electrode 11 and annular resistor negative electrode 9.

Both the damping cap 1 and the bonding substrate 2 are made of silicon, with a thickness of about 400 μm. The upper surface of the damping cap 1 adopts an open design, which is convenient for effective assembly with the device 26 to be adjusted.

Figures 2 and 3 show the structural diagram of the damping cap. The central giant area of the damping cap 1 is processed with a cavity 14, the surrounding area is the outer frame base 12, the upper part is a silicon elastic film 13, and the inner wall of the cavity 14 is deposited. There is an upper plate metal layer 15 , and a bonding metal layer 16 is processed on the lower surface of the outer frame base 12 .

The concave cavity 14 is formed by wet etching of silicon, the silicon elastic film 13 is formed by self-stop etching of heavily doped silicon surface, the upper plate metal layer 15 and the bonding metal layer 16 are the same material structure, and are deposited uniformly .

4, 5, 6, and 7 are structural diagrams of bonded substrates. Ring resistors 19, 20 are formed on the bond substrate 2, and a silicon dioxide layer 17 is deposited in a rectangular area surrounded by ring resistors 19, 20. A silicon dioxide layer 3, a silicon nitride layer 4, and a bonding metal layer 5 are sequentially deposited on the surrounding areas of the ring resistors 19 and 20, and a lower plate metal layer 18 is deposited on the silicon dioxide layer 17 in the central area. On the silicon dioxide layer 3 in the lower area of the substrate 2, ring-shaped resistor positive electrodes 6, 8, lower plate electrodes 11, silicon nitride layer 4, ring-shaped resistor negative electrodes 9, 7, and lower plate electrodes are fabricated sequentially from left to right. There is an upper plate electrode 10 on the silicon nitride layer 4 between 11 and the ring resistance negative pole 9, and the two ends of the ring resistance 21, 22 are respectively introduced into the The positive poles 6 and 8 of the ring resistance, the negative poles 7 and 9 of the ring resistance, and the metal layer 18 of the lower plate are connected to the electrode 11 of the lower plate through the lead wire 19 of the metal layer of the lower plate.

The structural shape and number of ring resistors 19, 20 can be changed, increased or decreased according to different design requirements and working environments.

The lower plate electrode 11 is the same as the ring resistor positive pole 6, 8, and the ring resistor negative pole 9, 7, but the thickness is different. The ring resistor positive pole 6, 8, and the ring resistor negative pole 9, 7 are thickened electrodes after electroplating, which is convenient for lead wires welding.

Figures 8 and 9 are the working structure diagrams of the pressure film damping adjustable device. The annular resistors 19 and 20 on the bonding substrate 2 are energized to generate heat, so that the packaged gas in the cavity 14 is heated and expanded, and the volume increases to promote silicon elasticity. The membrane 13 protrudes outwards to increase the pressure film damping of the device to be adjusted 26 by reducing the distance between the device to be adjusted 26 and the silicon elastic membrane 13; the lower plate electrode 18 and the concave cavity 14 on the bonding substrate 2 The upper plate electrode 15 on the inner wall is energized to generate electrostatic force, causing the silicon elastic membrane 13 to sag inward, so as to reduce the compression film damping of the device to be adjusted 26 by increasing the distance between the device to be adjusted 26 and the silicon elastic membrane 13 .

Fig. 10 is the structural diagram of bonding metal layer, and its structural material is consistent, and structural layer is made up of 2 metal film layers, and thickness is different, and the first layer that grows on semiconductor silicon material substrate layer 27 is titanium layer 28, and the second The layer is gold layer 29 .

The structural materials of the bonding metal layers 5 and 16 are the same, and the bonding adopts a low-temperature hot pressing method, so that the gold atoms on the surface of the gold layer 29 on the bonding metal layers 5 and 16 penetrate each other under the action of temperature and pressure to form a strong bond. combine.

Claims (2)

1. a MEMS inertial sensor structure press-filming damping tunable arrangement, is characterized in that: primary structure is made up of damper cap, bonded substrate, silicon dioxide layer, silicon nitride layer, bonding metal layer, resistance positive pole, resistance negative pole, top crown electrode, bottom crown electrode, fixed pedestal, silicon elastic film, cavity, top crown metal level, bottom crown metal level, top crown metal level lead-out wire, bottom crown metal level lead-out wire, ring resistance, ring resistance positive outside wire, ring resistance negative outside wire, upper doped with huge ring resistance (19 in bonded substrate (2), 20), ring resistance (19, 20) surrounding and the middle section enclosing are deposited with silicon dioxide layer (3), on the silicon dioxide layer (3) of bonded substrate (2) middle section, be manufactured with bottom crown metal level (18), on the silicon dioxide layer (3) of bonded substrate (2) peripheral regions, be deposited with silicon nitride layer (4), on the silicon dioxide layer (3) of the lower area of bonded substrate (2), be manufactured with ring resistance positive pole (6, 8), ring resistance negative pole (7, 9) bottom crown electrode (11), on the silicon nitride layer (4) of peripheral regions, be deposited with bonding metal layer (5), on the silicon dioxide layer (3) of the central area between bottom crown electrode (11) and ring resistance negative pole (9), be deposited with silicon nitride layer (4), on silicon nitride layer (4), be deposited with top crown electrode (10), ring resistance (19, 20) two ends are respectively by ring resistance positive outside wire (22, 24) ring resistance negative outside wire (23, 25) be incorporated into ring resistance positive pole (6, 8), ring resistance negative pole (7, 9), bottom crown metal level (18) is connected with bottom crown electrode (11) by bottom crown metal level lead-out wire (19), the upper airtight bonding of bonding metal layer (5) has damper cap (1), after the inner side processing cavity (14) of damper cap (1), form silicon elastic film (13) and housing pedestal (12), the inwall of cavity (14) is deposited with top crown metal level (15), the lower surface of housing pedestal (12) be deposited with bonding metal layer (16), in cavity (14) after the firm bonding of damper cap (1) and bonded substrate (2), be sealed with dilatancy gas.

2. MEMS inertial sensor structure press-filming damping tunable arrangement according to claim 1, it is characterized in that, described bonding metal layer (5,16), top crown metal level (15), bottom crown metal level (18), structural material is consistent, form by double layer of metal, be provided with titanium layer (28), i.e. Ti layer on silicon substrate 27 tops, be provided with gold layer, i.e. Au layer on titanium layer (28) top.