CN101317262A - Sensor device and method for manufacturing same - Google Patents

Abstract

A small sensor device having stable sensor characteristics, and a method for manufacturing such sensor device are provided. The sensor device is composed of a sensor substrate provided with a frame having an opening, a movable section movably held to the frame in the opening and a detecting section for outputting an electric signal based on the positional dislocation of the movable section; and a pair of package substrates bonded on the both planes of the sensor substrate. On the frame of the sensor substrate and each package substrate, a surface activation region is formed by using plasma, ion beam or atom beam of an inert gas. Troubles due to residual stress on the bonding section are eliminated by directly bonding the surface activation region of the sensor substrate on that of the package substrate at a room temperature.

Description

Sensor device and manufacture method thereof

Technical field

The present invention relates to the sensor device and the manufacture method thereof of a kind of for example acceleration sensor and gyrosensor.

Background technology

In recent years, the wafer-class encapsulation technology has attracted a large amount of concerns as the suitable manufacturing technology at compact sensor device (as acceleration sensor and gyrosensor).

For example, Japanese Patent Laid Open Publication No.2005-251898 discloses a kind of manufacturing technology of wafer-class encapsulation structure 200, as shown in Figure 25 A and 25B.In other words, sensor wafer 210 and encapsulated wafer 220 concern setting with aspectant each other, as shown in Figure 25 A.The metal wiring (extraction electrode) 217 that sensor wafer 210 has MEMS (microelectromechanical-systems) element 211 and is electrically connected with the transducing part (not shown) of MEMS element 211.Through hole distribution 224 that is electrically connected with metal wiring 217 and the recess 221 that provides the space to seal MEMS element 211 airtightly are provided encapsulated wafer 220.Then, by engaging forming wafer scale between sensor wafer 210 and the encapsulated wafer 220, described in Figure 25 B, obtained wafer-class encapsulation structure 200.At last, isolate a plurality of sensor devices from wafer-class encapsulation structure 200.

Facing on the surface of encapsulated wafer 220 of sensor wafer 210, form metal level 218, with MEMS element 211 that surrounds sensor main body and the metal wiring 217 that is electrically connected with MEMS element 211.On the other hand, form the metal level 228 that surrounds recess 221 on the surface of sensor wafer 210 facing of encapsulated wafer 220.In addition, the inboard of the metal level 218 on sensor wafer 210 forms the wiring layer 219 that is electrically connected with metal wiring 217, and the inboard of the metal level 228 on encapsulated wafer 220 forms the wiring layer 229 that is electrically connected with through hole distribution 224.In above-mentioned wafer-class encapsulation structure 200, the metal level 218 of sensor wafer 210 is by weld part 238, join the metal level 228 of encapsulated wafer 220 to as AuSn, the wiring layer 219 of sensor wafer 210 joins the wiring layer 229 of encapsulated wafer 220 to by weld part 239.

As MEMS element 211, acceleration sensor and gyrosensor are known.As acceleration sensor, there are pressure drag component type and capacitor type acceleration sensor.The resistance pressure type acceleration sensor can be surveyed acceleration according to the resistance change that (gauge) resistance is measured in the conduct that the strain by pressure drag component that produces when applying acceleration causes.Capacitance variations when capacitor type acceleration sensor energy basis applies acceleration between fixed electrode and the travelling electrode is surveyed acceleration.In the resistance pressure type acceleration sensor, have cantilever style and double bracing beam type acceleration sensor.Thereby the cantilever style acceleration sensor by rectangular frame part, be arranged at frame part inside the weight part with partly be connected weight at one end place with weight and partly can partly form with respect to the flexible beam that frame part moves.On the other hand, double bracing beam type acceleration sensor is partly formed by frame part, the weight part that is arranged at frame part inside and pair of flexible beam, this extends in the opposite direction and is configured to support the weight part from the weight part flexible beam part, and the weight part can be moved with respect to frame part.In recent years, acceleration sensor at each orientation detection acceleration of three orthogonal directions has for example also been proposed in Japanese Patent Laid Open Publication No.2004-109114 and No.2004-233071.This acceleration sensor has frame part, is arranged at weight part and four flexible beam parts of frame part inside, and these four flexible beams extend on four direction and are configured to support the weight part, thereby the weight part can move with respect to frame part.

Yet, in above-mentioned wafer-class encapsulation structure 200, supply with the scolder of specified amount for metal level 228 and wiring layer 229 by the scolder injection method, make between the metal level (218,228) and joint between the wiring layer (219,229).Then, the stepped construction of sensor wafer 210 and encapsulated wafer 220 being carried out reflow soldering handles.Therefore, when using resistance pressure type acceleration sensor main body, there is a problem,, changes so sensor characteristics takes place promptly because near the residual stress joint interface partly has influence to flexible beam as MEMS element 211.Along with the sensor device size reduces, the influence of residual stress increases.

Summary of the invention

Therefore, consider top problem, a kind of sensor characteristics that provides that the present invention relates generally to changes less sensor device, this sensor device will be by having the compact sensor element, join base plate for packaging to as the sensor base plate of acceleration sensor and gyrosensor and form, almost do not produce residual stress in the bonding part.

In other words, sensor device of the present invention comprises:

Sensor base plate, it comprises framework with opening, remains on the movable part in the described opening and be configured to probe portion according to the displacement output signal of telecommunication of described movable part movably;

Join one of the apparent surface's of described sensor base plate first base plate for packaging to;

Join second base plate for packaging on another surface of described sensor base plate to;

Its middle frame has first surface active region and second surface active region, this first surface active region is formed on whole outer the facing on the surface of first base plate for packaging of placing of framework, so that the first surface active region surrounds described movable part, this second surface active region is formed on whole outer the facing on the surface of second base plate for packaging of placing of framework, so that the second surface active region surrounds described movable part

Engaging between sensor base plate and first base plate for packaging be the first surface active region be formed on first base plate for packaging on the surface activation zone between do not have the solid phase of diffusion directly to engage,

Engaging between sensor base plate and second base plate for packaging be the second surface active region be formed on second base plate for packaging on the surface activation zone between do not have the solid phase of diffusion directly to engage.

According to the present invention, because each of first and second base plate for packaging all directly joins sensor base plate to by the solid phase that does not have diffusion, so can avoid following problems, promptly using heat treatment, in the situation of reflow soldering,, the residual stress of office, junction surface changes owing to causing sensor characteristics as joint method.In addition, a surface of sensor base plate is placed outside framework whole and is joined first base plate for packaging to, another surface of sensor base plate joins second base plate for packaging on the whole surface of framework, the inside of sensor device can be sealed with outside mode with sealing.For example, when on sensor base plate, forming acceleration sensor, can realize inert gas atmosphere near the movable part in sensor device.Alternatively, when on sensor base plate, forming gyrosensor, realize the atmosphere of the decompression of higher vacuum near can the movable part in sensor device.

Directly engage in order to obtain solid phase with good bond strength, preferably the surface activation zone of the surface activation of first surface active region, second surface active region, first base plate for packaging zone and second base plate for packaging is any one in the surface of the surface of surface, ion beam irradiation of plasma treatment and atomic beam radiation.To be Si directly engage with solid phase between the Si in the engaging between the surface activation zone on joint between the surface activation zone on the also preferred first surface active region and first base plate for packaging and second surface active region and second base plate for packaging at least one, Si and SiO ₂Between solid phase directly engage and SiO ₂With SiO ₂Between solid phase any one in directly engaging.Alternatively, preferably Au directly engages with solid phase between the Au at least one in the engaging between the surface activation zone on joint between the surface activation zone on the first surface active region and first base plate for packaging and second surface active region and second base plate for packaging, Cu directly engages with solid phase between the Cu and Al and during solid phase between the Al directly engages any one.

For the sealing that improves sensor device and improve joint reliability, at least one in preferred first surface active region and the second surface active region comprise be formed on described framework whole outer place place with the outer annular surface active region that surrounds described movable part with outside described framework whole be formed on described outer surface active region the inboard to surround the annular inside surface active region of described movable part.In this case, in order to improve sealing reliability, form the auxiliary seals zone, be used for being connected between the surface activation zone and inner surface active region outside particularly preferably in a plurality of positions at the preset distance that is spaced apart from each other on the peripheral direction of framework.

From boosting productivity and obtaining the viewpoint of good bond intensity, each of the first surface active region of preferred sensor substrate and the surface activation zone of first base plate for packaging all is the activated surface with Au film of 500nm or littler thickness.

In addition, when sensor base plate have can with the integrated circuit of described probe portion cooperating, and this integrated circuit is when through hole wired electric in being formed on first base plate for packaging is connected, and integrated circuit more preferably is arranged to surround the opening of framework preferably near the opening setting of framework.Because the transducing part that is arranged in the opening of framework is provided with away from the bonding part between first base plate for packaging and the sensor base plate by integrated circuit, so can further reduce the influence of bonding part, therefore can more effectively stop the variation of sensor characteristics to transducing part.

As preferred implementation of the present invention, when on sensor base plate, forming acceleration sensor, the beam part that preferred movable part comprises weight and extends between framework and weight, probe portion comprises at least one pressure drag component that is formed on the described beam part.In addition, when on sensor base plate, forming gyrosensor, preferred movable part comprises by first mass of vibrating mass vibration and second mass that couples with first mass, and the displacement conversion that probe portion is configured to second mass that causes when applying revolving force in the first mass vibration processes is the signal of telecommunication.

In addition, preferably by using the SOI substrate to form sensor base plate, described SOI substrate has across insulating barrier and is positioned at silicon layer on the silicon substrate.In addition, when sensor base plate has can be with the integrated circuit of probe portion cooperating the time,, can further reduce the thickness of sensor device by on the silicon layer of SOI substrate, forming pressure drag component and integrated circuit.

In addition, be formed on than the position of the more close movable part of first surface active region and during when sensor base plate has with conductor layer that probe portion is electrically connected, first base plate for packaging has through hole distribution and the wiring layer that is connected with the through hole wired electric, does not have the solid phase of diffusion directly to engage between the activated surface that engaging between first base plate for packaging and the sensor base plate further is included in conductor layer and the activated surface of wiring layer.In this case, can obtain being electrically connected between the close encapsulation of sensor device and first base plate for packaging and the sensor base plate simultaneously.If necessary, the use same solid phase that can form close encapsulation and electrical connection simultaneously directly engages and joins second base plate for packaging to sensor base plate.

The invention further relates to the manufacture method that a kind of sensor device is provided, the problem that it can avoid the residual stress by the office, junction surface to cause, for example variation of sensor characteristics.In other words, manufacture method of the present invention comprises the steps:

Sensor base plate is provided, joins one of apparent surface's first base plate for packaging of sensor base plate and second base plate for packaging that joins another surface of sensor base plate to, described sensor base plate comprises framework with opening, remains on the movable part in the described opening and be configured to probe portion according to the displacement output signal of telecommunication of described movable part movably;

Outside framework whole, place in the face of forming the first surface active region on the framework surface of first base plate for packaging, so that the first surface active region surrounds movable part;

Outside framework whole, place in the face of forming the second surface active region on the surface of second base plate for packaging, so that the second surface active region surrounds movable part;

On each of first base plate for packaging and second base plate for packaging, all form the surface activation zone; With

In room temperature, between the surface activation zone of first surface active region and first base plate for packaging, form and directly engage, between the surface activation zone of second surface active region and second base plate for packaging, form and directly engage.

According to manufacture method of the present invention, directly engage because when room temperature, between each of sensor base plate and first and second base plate for packaging, all form solid phase, so can stop the variation of the sensor characteristics that the residual stress by the office, junction surface causes reliably.

For the solid phase that obtains to have good bond intensity directly engages, preferably form the surface activation zone of first surface active region, second surface active region, first base plate for packaging and second base plate for packaging by in the atomic beam, ion beam and the plasma that use inert gas any one.

In addition, preferably in identical chamber, form first surface active region and second surface active region step, form each the step and the direct integrating step in surface activation zone of first base plate for packaging and second base plate for packaging, the inside of described chamber is controlled as the atmosphere of expectation before direct engagement step.In this case, in sensor device, set the atmosphere of expectation according to the kind of transducer.For example, when on sensor base plate, forming acceleration sensor, directly carrying out the atmosphere adjustment by introducing inert gas before the engagement step, thereby directly in sensor device, obtaining inert gas atmosphere after the engagement step to chamber.Alternatively, when forming gyrosensor on sensor base plate, directly carrying out the atmosphere adjustment before the engagement step, thereby obtaining the reduced atmosphere of higher vacuum, they are different with the atmosphere that is used to form surface activation zone step.As a result, after direct engagement step, the inside of sensor device can remain in the atmosphere of decompression.

When sensor base plate have can with the integrated circuit of probe portion cooperating, the wiring lead layer that is connected with the pad of integrated circuit at the one end, be used to provide the first metal layer of first surface active region, with be connected with the wiring lead layer other end and be used for second metal level that is connected with the through hole distribution, and first base plate for packaging has the through hole distribution, by being formed on jointing metal layer in the face of the position of the first metal layer with the first metal layer identical materials, with by with the second metal level identical materials be formed on the through hole distribution in the face of the distribution metal level at place, the end of sensor base plate the time, preferably when room temperature, form the direct joint between the activated surface of the activated surface of the direct joint between the activated surface of the activated surface of the first metal layer and jointing metal layer and second metal level and distribution metal level simultaneously.In addition, preferably form wiring lead layer, the first metal layer and second metal level: form lower metal layer as etch stopper by the operation that comprises the steps; By using the metal material different forming metal level on the lower metal layer with lower metal layer; The last metal level of the etching location corresponding with the first metal layer and second metal level only is up to exposing described lower metal layer.In this case, form each other and flush, obtain good engagement state, can improve the production efficiency of sensor device simultaneously so can stablize because have first and second metal levels of outstanding surface smoothness.

To obtain good bond strength in order engaging, the surface activation zone of the first surface active region and first base plate for packaging just in time to be contacted each other by room temperature.In order to satisfy this requirement, preferably form the first surface active region: on the framework of sensor base plate, form multilayer insulating film by the operation that comprises the steps; Form the flat surfaces of multilayer insulating film by the described multilayer insulating film of an etchback part; On flat surfaces, form metal level; Atomic beam, ion beam or plasma with the surface emissivity inert gas of giving metal level.Multilayer insulating film preferably include the silicon oxide film that is formed on the framework first dielectric film, be formed on the silicon nitride film on first dielectric film second dielectric film, be formed at least one interlayer dielectric on second dielectric film the 3rd dielectric film, be formed on the 4th dielectric film of the passivating film on the 3rd dielectric film.In this case, preferably carry out etchback as etch stopper and form flat surfaces by use other dielectric films except that the 4th dielectric film.The fabulous surface smoothness of the underlayer insulating film that forms by etchback is reflected to the metal level that forms on the underlayer insulating film.Therefore, can obtain to be suitable for the metal level that room temperature directly engages.As another preferred implementation that forms flat surfaces, carry out etchback as etch stopper by the silicon nitride film that uses second dielectric film.Alternatively, form flat surfaces by the operation that comprises the steps: use the first etchback step of the silicon nitride film of second dielectric film as etch stopper: and the silicon oxide film that passes through use first dielectric film that carries out after the first etchback step is as the second etchback step of etch stopper.

In addition, when sensor base plate has can be with the integrated circuit of probe portion cooperating, be formed on the conductor layer position and that be electrically connected with described integrated circuit than the more close described movable part of described first surface active region, and first base plate for packaging has the through hole distribution with wiring layer that the through hole wired electric is connected the time, form simultaneously when room temperature preferably that direct between the surface activation zone of first surface active region and first base plate for packaging engages and the activated surface of the activated surface of conductor layer and described wiring layer between direct joint.In this case, can form being electrically connected between the mechanical engagement of first base plate for packaging and sensor base plate and conductor layer and the wiring layer simultaneously.

Description of drawings

Figure 1A and 1B are respectively schematic plan view and the end views according to the wafer-class encapsulation structure of first execution mode;

Fig. 2 A and 2B are respectively schematic plan view and the end views from the sensor device of wafer-class encapsulation structure acquisition;

Fig. 3 A is the top view of sensor base plate, and Fig. 3 B is the cross-sectional view along the line B-A ' of Fig. 3 A;

Fig. 4 is the bottom view of sensor base plate;

Fig. 5 is the circuit diagram of sensor base plate;

Fig. 6 A is the top view of first base plate for packaging, and Fig. 6 B is the cross-sectional view along the line A-A ' of Fig. 6 A;

Fig. 7 is the bottom view of first base plate for packaging;

Fig. 8 A and 8B are respectively the top view and the cross-sectional views of second base plate for packaging;

Fig. 9 is the schematic amplification cross-sectional view of the bonding part between the sensor base plate and first base plate for packaging;

Figure 10 A is the top view according to the sensor base plate of the modification of present embodiment, and Figure 10 B is the cross-sectional view along the line B-A ' among Figure 10 A;

Figure 11 A is the top view according to first base plate for packaging of the modification of present embodiment, and Figure 11 B is the cross-sectional view along the line A-A ' among Figure 11 A;

Figure 12 is the schematic amplification cross-sectional view of the bonding part between first base plate for packaging of the sensor base plate of Figure 10 A and Figure 11 A;

Figure 13 A is the cross-sectional view that display surface activates step, and Figure 13 B is the cross-sectional view that shows the atmosphere set-up procedure, and Figure 13 C is the cross-sectional view that shows the room temperature engagement step;

Figure 14 A and 14B are respectively schematic plan view and the end views according to the wafer-class encapsulation structure of second execution mode, and Figure 14 C is the schematic cross section of the sensor device in this wafer-class encapsulation structure;

Figure 15 A is the top view of sensor base plate, and Figure 15 B is the cross-sectional view along the line A-A ' among Figure 15 A;

Figure 16 A is to show that each is all at the cross-sectional view of the execution mode of the wiring lead that is electrically connected between pad and second metal level to 16C;

Figure 17 A is the schematic cross section of making the method for sensor device according to second execution mode to 17F;

Figure 18 A is the top view of first base plate for packaging, and Figure 18 B is the cross-sectional view along the line A-A ' among Figure 18 A;

Figure 19 A and 19B are respectively the top view and the cross-sectional views of second base plate for packaging;

Figure 20 is the schematic cross section according to the gyrosensor device of the 3rd execution mode;

Figure 21 is the schematic plan view according to the sensor base plate of the 3rd execution mode;

Figure 22 is the enlarged drawing of the relevant portion of sensor base plate;

Figure 23 is the schematic plan view according to first base plate for packaging of the 3rd execution mode;

Figure 24 is the schematic bottom view of first base plate for packaging; With

Figure 25 A and 25B are the schematic diagrames of making the method for conventional sensors device.

Embodiment

With reference to accompanying drawing, will explain sensor device of the present invention and manufacture method in detail below.

(first execution mode)

In the present embodiment, as Figure 1A, shown in 1B and Fig. 2 A and the 2B, explained following situation, promptly make sensor device: make wafer-class encapsulation structure 100 by following step, it comprises one of the semiconductor wafer 10 that wherein is integrated with a plurality of acceleration sensors unit, the apparent surface's who joins semiconductor wafer 10 to first encapsulated wafer 20 and second encapsulated wafer 30 that joins another surface of semiconductor wafer 10 to, then wafer-class encapsulation structure 100 is cut into the size of sensor device.Therefore, in the sensor device of present embodiment, be defined as sensor base plate 1 corresponding to the part of semiconductor wafer 10.Part corresponding to first encapsulated wafer 20 is defined as first base plate for packaging 2.Part corresponding to second encapsulated wafer 30 is defined as second base plate for packaging 3.

The present embodiment of making sensor device from wafer-class encapsulation structure 100 has following advantage, can obtain a plurality of compact sensor devices once.Yet sensor device of the present invention is not limited to this manufacture method.For example, can make each sensor device separately by following step: preparation has the sensor base plate and a pair of first and second base plate for packaging of single-sensor element, and when room temperature (normal temperature), directly sensor base plate is joined to each first and second base plate for packaging, as hereinafter described.

In the present embodiment, the supporting substrate 10a that forms by silicon substrate as the SOI wafer of semiconductor wafer 10, be formed on insulating barrier (the imbedding oxide-film) 10b on the supporting substrate 10a, as silicon oxide film be formed on n type silicon layer (active layer) 10c composition on the insulating barrier 10b.Form each acceleration sensor unit by handling this SOI wafer.Form each first encapsulated wafer 20 and second encapsulated wafer 30 by handling silicon wafer.In the present embodiment, the thickness of the supporting substrate 10a of SOI substrate at 300 μ m in the scope of 500 μ m, the thickness of insulating barrier 10b at 0.3 μ m in the scope of 1.5 μ m, the thickness of silicon layer 10c at 4 μ m in the scope of 10 μ m.In addition, as the surface of the silicon layer 10c on the general surface of SOI wafer corresponding to (100) surface.The thickness of silicon wafer that is used for first encapsulated wafer 20 at 200 μ m in the scope of 300 μ m, the thickness of silicon wafer that is used for second encapsulated wafer 30 at 100 μ m in the scope of 300 μ m.These one-tenth-value thickness 1/10s only are exemplary, and the present invention is not limited to them.

Fig. 3 A and 3B are respectively the top view and the cross-sectional views of an acceleration sensor unit (corresponding to the zone among Figure 1A " A ") of formation in sensor base plate 1.In addition, Fig. 4 is the bottom view of acceleration sensor unit.Each acceleration sensor unit all has the frame part 11 (for example rectangular frame part) that has inside opening, the weight part 12 that is arranged at frame part 11 inside and each all forms strip and has four flexible flexible portions 13.Weight part 12 is supported on the top surface side (Fig. 3 A) of sensor unit by flexible portion 13, thereby can move with respect to frame part 11 in the mode of swing.In other words, weight part 12 is supported on the inside opening of frame part 11 in the mode of swinging towards four flexible portions 13 that frame part 11 extends movably by four limits from the weight part.Form frame part 11 by supporting substrate 10a, insulating barrier 10b and the silicon layer 10c that uses above-mentioned SOI substrate.On the other hand, as shown in Fig. 3 B, form flexible portion 13 by the silicon layer 10c that uses the SOI substrate.Therefore, flexible portion 13 has than frame part 11 abundant little thickness.

Weight part 12 has by four flexible portions 13 and supports to the core 12a with rectangular solid shape of frame part 11 and four 12b of leaf portion that each all has the rectangular solid shape, at the top surface side place of sensor base plate 1, leaf portion one is connected to four angles of core 12a.In other words, when when sensor base plate 1 is watched, each 12b of leaf portion is arranged in the space that is surrounded by frame part 11, core 12a and two flexible portions 13 of extending on mutually orthogonal directions.Numeral 14 indicates the slit that is formed between each 12b of leaf portion and the frame part 11.Distance by flexible portion 13 between the adjacent 12b of leaf portion is greater than the width dimensions of flexible portion 13.Supporting substrate 10a, insulating barrier 10b and silicon layer 10c by above-mentioned SOI wafer form core 12a.On the other hand, the supporting substrate 10a by the SOI wafer forms each 12b of leaf portion.In the top surface side of sensor base plate 1, the top surface of each 12b of leaf portion is arranged at the position lower than the top surface of core 12a, promptly is arranged at the side (Fig. 4) near sensor base plate 1 bottom.Preferably by using conventional photoetching and etching technique to form frame part 11, weight part 12 and the flexible portion 13 of sensor base plate 1.

By the way, as Fig. 3 A, shown in the right lower quadrant of 3B and 4 in each, when the horizontal direction of frame part 11 during corresponding to " x " axle, with " x " axle quadrature horizontal direction corresponding to " y " axle, the thickness direction of sensor base plate 1 is corresponding to " z " axle, weight part 12 by core 12a both sides the pair of flexible part 13 of extending on " x " direction of principal axis and the both sides of core 12a on " y " direction of principal axis, extend another flexible portion 13 is supported to frame part 11.Define above-mentioned " x ", the rectangular coordinate system of " y " and " z " has initial point, the center of the top surface of the weight part 12 that it forms corresponding to the silicon layer 10c by sensor base plate 1.

, promptly be positioned on the flexible portion 13 on Fig. 3 A right side at the square upwardly extending flexible portion 13 of " x " axle from the core 12a of weight part 12, (Rx2 Rx4), is formed with pressure drag component Rz2 near frame part 11 to be formed with a pair of pressure drag component near core 12a.On the other hand, from the core 12a of weight part 12 at the upwardly extending flexible portion 13 of " x " axle losing side, promptly be positioned on the flexible portion 13 in Fig. 3 A left side, be formed with a pair of pressure drag component (Rx1 near core 12a, Rx3), be formed with pressure drag component Rz3 near frame part 11.In this, (Rx3 Rx4) is used for surveying acceleration on " x " direction of principal axis to four pressure drag components that form near core 12a for Rx1, Rx2.(Rx3 Rx4) forms with the long rectangular shape of even shape each pressure drag component for Rx1, Rx2, and roughly the longitudinal direction with flexible portion 13 is identical to be arranged to make the length direction of pressure drag component.In addition, these pressure drag components are connected by distribution (being formed on diffusion layer distribution and metal wiring 17 on the sensor base plate 1), thereby obtain the bridge circuit Bx shown in Fig. 5 left side.(Rx3 Rx4) is formed on the stress build up location that wherein produces the flexible portion 13 of stress build up when applying acceleration on " x " direction of principal axis to pressure drag component for Rx1, Rx2.

From the core 12a of weight part 12 at the square upwardly extending flexible portion 13 of " y " axle, promptly be positioned on the flexible portion 13 of Fig. 3 A upside, (Ry1 Ry3), is formed with pressure drag component Rz1 near frame part 11 to be formed with a pair of pressure drag component near core 12a.On the other hand, from the core 12a of weight part 12 at the upwardly extending flexible portion 13 of " y " axle losing side, promptly be positioned on the flexible portion 13 of Fig. 3 A downside, be formed with a pair of pressure drag component (Ry2 near core 12a, Ry4), be formed with pressure drag component Rz4 near frame part 11.In this, (Ry3 Ry4) is used for surveying acceleration on " y " direction of principal axis to four pressure drag components that form near core 12a for Ry1, Ry2.(Ry3 Ry4) forms with the long rectangular shape of even shape each pressure drag component for Ry1, Ry2, and roughly the longitudinal direction with flexible portion 13 is identical to be arranged to make the length direction of pressure drag component.In addition, these pressure drag components are connected by distribution (being formed on diffusion layer distribution and metal wiring 17 on the sensor base plate 1), thereby obtain the bridge circuit By shown in Fig. 5 middle part.(Ry3 Ry4) is formed on the stress build up location that wherein produces the flexible portion 13 of stress build up when applying acceleration on " y " direction of principal axis to pressure drag component for Ry1, Ry2.

In addition, pressure drag component (Rz1, the Rz2 that forms near frame part 11, Rz3, Rz4) be used for surveying acceleration on " z " direction of principal axis, and be connected by distribution (being formed on diffusion layer distribution and metal wiring 17 on the sensor base plate 1), thus the bridge circuit Bz shown in acquisition Fig. 5 right side.Pressure drag component (Rz1, Rz4) be arranged on the pair of flexible part 13, so that the length direction of pressure drag component roughly the longitudinal direction with flexible portion 13 is identical, pressure drag component (Rz2, Rz3) be arranged on another on the flexible portion 13 so that the length direction of pressure drag component roughly width (laterally) direction with flexible portion 13 is identical.

Fig. 3 A has only shown the part of the metal wiring 17 near described in the back second metal level 19 the sensor base plate 1.In addition, do not show the diffusion layer distribution among Fig. 3 A.

Form pressure drag component (Rx1 is to Rx4, and Ry1 is to Ry4, and Rz1 is to Rz4) and diffusion layer distribution by the predetermined formation position of p type doping impurity being advanced silicon layer 10c with suitable concentration.On the other hand, the mode by sputter or gas deposition forms metal film (as the Al film, Al alloy film etc.) on dielectric film 16, then by using conventional photoetching and etching technique that the metal film composition is obtained metal wiring 17.Metal wiring 17 is connected with the diffusion layer wired electric by the contact hole that is formed in the dielectric film 16.

As Fig. 6 A, shown in the 6B and 7, forming first base plate for packaging 2 in the face of the surface of sensor base plate 1, it has displacement for the movable part of being made up of the weight part 12 and the flexible portion 13 of sensor base plate 1 provides the recess 21 in space and centers on recess 21 and be formed on a plurality of through holes 22 (for example eight through holes) on the thickness direction.Each peripheral shape of the sensor base plate 1 and first base plate for packaging 2 all is a rectangular shape, and first base plate for packaging 2 forms has the external dimensions identical with sensor base plate 1.

First base plate for packaging 2 has the dielectric film 23 that is formed by opaque film (silicon oxide film) on the apparent surface of thickness direction and on the inner surface of through hole 22.Therefore, the part of dielectric film 23 is between the inner surface of through hole distribution 24 and each through hole 22.In this embodiment, on the peripheral direction of first base plate for packaging 2, form eight through hole distributions 24 that are spaced apart from each other.As the material of through hole distribution 24, for example can use copper.Alternatively, can use tweezer.

In addition, the through hole distribution 24 that is formed in first base plate for packaging 2 preferably has conical in shape, thereby in the face of the area of the end of sensor base plate 1 area greater than the other end.In the conical through-hole in being formed at first base plate for packaging by electroplating when forming the through hole distribution, supply with electroplate liquid from having, deposit towards the other end that has than large opening area from end with smaller opening area thereby distribution forms metal than the end of large opening area.Thus, the situation that has constant aperture area with through hole is compared, and the bubble that is easy to produce in through hole is discharged to the outside.In addition,, in through hole, produce the metal ion gathering, improve the metal deposition rate so can stop because electroplate liquid is easy to enter through hole.As a result, have following advantage, can form through hole distribution 24 effectively with uniform thickness.With (top) surface in the face of first base plate for packaging 2 at the surperficial relative side place of sensor base plate 1 on be formed for a plurality of electrodes 25 of outside connection, thereby be electrically connected with through hole distribution 24.The electrode 25 of present embodiment has the peripheral shape of rectangle.

As shown in Figure 8A and 8B, forming second base plate for packaging 3 in the face of the surface of sensor base plate 1, its have have desired depth (for example 5 μ m are to 10m) so that the recess 31 in space is provided for the displacement of weight part 12.Can form recess 31 by using conventional photoetching and etching technique.Each all has the peripheral shape of rectangle the sensor base plate 1 and second base plate for packaging 3.Second base plate for packaging 3 forms has the external dimensions identical with sensor base plate 1.

When the thickness of the part of the core 12a that is used to form weight part 12 of supporting substrate 10a and weight 12b is defined as than the thickness of other parts that are used to form frame part 11 of supporting substrate 10a less than the corresponding size of displacement that allows on the thickness direction of sensor base plate 1 with weight part 12, between the weight part 12 and second base plate for packaging 3, can obtain to be used to the gap that makes weight part 12 carry out displacement, not be used in and form recess 31 in second base plate for packaging 3.

Next, the bonding part between the explanation sensor base plate 1 and first base plate for packaging 2.On the frame part 11 of each acceleration sensor unit, outside frame part whole, place, form the first metal layer 18 at a side place, so that it surrounds the movable part of being made up of weight part 12a and flexible portion 13 in the face of first base plate for packaging 2.As shown in Figure 9, do not have the solid phase of diffusion directly to engage (solid-phase direct bonding) between the activated surface by the frame-like metal level 28 on the activated surface of the first metal layer 18 of each acceleration sensor unit and the respective regions that is formed on first base plate for packaging 2 and form bonding part between the sensor base plate 1 and first base plate for packaging 2.Obtain this solid phase and directly engage by pushing activated surface when the room temperature each other.

In addition, first base plate for packaging 2 has a plurality of wiring layers 29, and wiring layer is formed on the inboard of frame-like metal level 28 and around recess 21, and is electrically connected with through hole distribution 24.The quantity of the wiring layer 29 that for example, forms in the present embodiment is eight.Each wiring layer 29 all is connected with through hole distribution 24 at the place, end of its longitudinal direction.Wiring layer 29 is positioned at a side of the first metal layer 18 more close weight parts 12 of ratio sensor substrate 1, and also be formed on frame part 11 on second metal level 19 be electrically connected.The outside that is connected the metal wiring 17 that is positioned at sensor base plate 1 between second metal level 19 and the wiring layer 29.

In the face of on the surface of first base plate for packaging 2, be formed with dielectric film 16 at sensor base plate 1, it comprises the silicon oxide film on the silicon layer 10c and the stacked film of silicon nitride film.The first metal layer 18, second metal level 19 and metal wiring 17 are formed on the dielectric film 16.

By using identical metal material to form the first metal layer 18 and metal level 28.For example, preferably use Au, Cu or Al are as metal material.Especially preferably use Au.The metal material that uses in the present embodiment is Au.For the first metal layer 18 that improves Au and the cohesive force between the dielectric film 16, form the Ti film betwixt as the intermediate layer.In other words, first metal film 18 is made up of with the stacked film that is formed on the Au film on the Ti film the Ti film that is formed on the dielectric film 16.

Similarly, by using identical metal material to form second metal level 19 and wiring layer 29.For example, preferably use Au, Cu or Al are as metal material.Especially preferably use Au.The metal material that uses in the present embodiment is Au.For second metal level 19 that improves Au and the cohesive force between the dielectric film 16, form the Ti film betwixt as the intermediate layer.In other words, second metal film 19 is made up of with the stacked film that is formed on the Au film on the Ti film the Ti film that is formed on the dielectric film 16.

For each of the first metal layer 18 and second metal level 19, the thickness of Ti film preferably is located at 15 in the scope of 50nm in the present embodiment, and the thickness of Au film is made as 500nm, and the thickness of metal wiring 17 is made as 1 μ m.These one-tenth-value thickness 1/10s only are exemplary, and the present invention is not limited to them.In the situation of using the Au film, from improving the viewpoint of productive rate, thickness preferably is not more than 500nm in engaging operation.The gold copper-base alloy that comprises the impurity outside the proof gold by use forms the Au film.In the present embodiment, the Ti film forms the tack coat that is used to improve the cohesive force between Au film and the dielectric film 16.Replace the Ti film, can use Cr, Nb, Zr, TiN, TaN etc. are as the material of tack coat.

As mentioned above, when forming the first metal layer 18 and second metal level 19, be effectively for reducing production costs, because can form those metal levels simultaneously with roughly the same thickness by the identical metal material of use.In other words, because forming each other on sensor base plate 1, the first metal layer 18 and second metal level 19 flush, metal level 28 and wiring layer 29 form each other on first base plate for packaging 2 and flush, so apply uniform pressure can for the joint interface between the sensor base plate 1 and first base plate for packaging 2.Thereby, can stable properties obtain that the first metal layer 18 directly engages with solid phase between the metal level 28 and second metal level 19 directly engages with solid phase between the wiring layer 29.

In addition, as shown in Figure 10A and 10B, thereby thereby the first metal layer 18 can place the outer metal level 18a of the ring-type of surrounding weight part 12 and form whole outward by what be formed on frame part 11 at the whole outer ring-type inner metal layer 18b that is formed on outer metal level 18a inboard encirclement weight part 12 that places of frame part 11.In this case, as shown in Figure 11 A and 11B, the metal level 28 of also preferred first base plate for packaging 2 is made up of with the ring-type inner metal layer 28b that is arranged on outer metal level 28a inboard the outer metal level 28a of ring-type, and outer metal level 28a of ring-type and ring-type inner metal layer 28b are to form with the first metal layer 18 aspectant relations.Alternatively, the metal level 28 of first base plate for packaging 2 can be formed by the single metal layer, and its width dimensions that has is confirmed as across outside between metal level 18a and the inner metal layer 18b.Thereby, when when forming two the joint between the first metal layer 18 and the metal level 28, as shown in Figure 12, can further improve the effect of the inside (i.e. the part of Yi Donging) that seals the acceleration sensor unit airtightly.In Figure 12, recess 21, the second metal levels 19 that the coupling part 19b with metal wiring 17 is arranged in first base plate for packaging 2 are electrically connected with this coupling part 19b.

In Figure 10 A, numeral 15 is illustrated in the auxiliary seal layer that extends between outer metal level 18a and the inner metal layer 18b.Auxiliary seal layer 15 is arranged on a plurality of positions of the preset distance that is spaced apart from each other on the peripheral direction of frame part 11.In addition, as shown in Figure 11 A, be on first base plate for packaging 2 in auxiliary seal layer 15 corresponding position and be formed with auxiliary seal layer 26 with sensor base plate 1.Therefore, when first base plate for packaging 2 joined sensor base plate 1 to, the solid phase that also can obtain between the activated surface of auxiliary seal layer (15,26) directly engaged.In addition, by forming the following effect of auxiliary seal layer (15,26) expectation.For example, when having exterior materials on the metal level 28a outside, can reduce outer metal level (18a, 28a) sealing between.Alternatively, when on inner metal layer 28b, having other exterior materials, can reduce inner metal layer (18b, 28b) sealing between.In these cases, be difficult to the inside of seal sensor device airtightly.Yet,, obtain a plurality of enclosure spaces outside between metal level 18a and the inner metal layer 18b when when forming joint between the auxiliary seal layer (15,26).In other words, when wherein owing to exterior materials causes metal level (18a outside, the zone that the sealing of the joint 28a) reduces is away from wherein owing to other exterior materials cause at inner metal layer (18b, the sealing of the joint 28b) reduces when regional, spatially cover each other by the joint between the auxiliary seal layer (15,26) in these zones.In brief, can further improve reliably by outer metal level (18a, 28a) joint between and inner metal layer (18b, 28b) sealing brought of the joint between by auxiliary seal layer (15,26).

In the present embodiment, as mentioned above, place outside frame part 11 whole, the first metal layer 18 is formed in the face of on the surface of first base plate for packaging 2, so that it surrounds weight part 12, metal level 28 is formed on the respective regions place on first base plate for packaging 2.Alternatively, preferably replace the first metal layer 18 to form Si layer or SiO ₂Layer replaces metal level 28 to form Si layer or SiO ₂Layer.In brief, can directly engage with solid phase between the Si by Si, Si and SiO ₂Between solid phase directly engage and SiO ₂With SiO ₂Between solid phase any one in directly engaging form engaging between sensor base plate 1 and first base plate for packaging 2.

In order directly to engage forming the solid phase that not have to spread between sensor base plate 1 and first base plate for packaging 2, before engagement step, be pre-formed the activated surface of the first metal layer 18 and metal level 28.In the present embodiment, by atomic beam, ion beam or the plasma of radiation argon obtain activated surface with the surface of cleaning and activate the first metal layer 18 and metal level 28 in a vacuum.Similarly, on second metal level 19 and wiring layer 29, form activated surface.Subsequently, carry out above-mentioned room temperature joint method.In other words, by apply that suitable load forms simultaneously that direct between the first metal layer 18 and the metal level 28 engages when the room temperature and second metal level 19 and wiring layer 29 between direct the joint.

Next, the bonding part between the explanation sensor base plate 1 and second base plate for packaging 3.The frame part 11 of each acceleration sensor unit has by surface activation handles above the whole periphery be formed on frame part 11 lip-deep surface activation zone to second base plate for packaging 3.By directly engaging the bonding part that forms between the sensor base plate 1 and second base plate for packaging 3 with handling in the solid phase that does not have between the surface activation zone that forms on second base plate for packaging, 3 respective surfaces to spread by surface activation in the surface activation of each acceleration sensor unit zone.By when the room temperature each other the compressive surface active region obtain this solid phase and directly engage.Therefore, directly engage the joint interface that forms in this situation by the solid phase between Si and the Si.Alternatively, can form SiO on one in the sensor base plate 1 and second base plate for packaging 3 ₂Layer, thus Si and SiO obtained ₂Between solid phase directly engage.In addition, all form SiO on can be in the sensor base plate 1 and second base plate for packaging 3 ₂Layer, thus SiO obtained ₂And SiO ₂Between solid phase directly engage.In addition, the solid phase between the surface activation zone of also preferred use metal material directly engages, as the direct joint between above-mentioned Au and the Au.Thereby, if necessary,, can directly engage in formation solid phase between sensor base plate 1 and second base plate for packaging 3 with the same in forming the situation that solid phase directly engages between sensor base plate 1 and first base plate for packaging 2.

In order to make wafer-class encapsulation structure 100, from the viewpoint of effectively exerting pressure for joint interface, hope be directly to join second base plate for packaging 3 to sensor base plate 1, directly join first base plate for packaging 2 to sensor base plate 1 then.

With reference to Figure 13 A to 13C, below engagement step between in specific explanations sensor base plate 1 and first base plate for packaging 2 and second base plate for packaging 3 each.

At first, as shown in Figure 13 A, sensor base plate 1, first base plate for packaging 2 and second base plate for packaging 3 are placed among the cavity C H, discharge the air in the chamber, make it be no more than predetermined vacuum level (for example 1 * 10 ^-5Pa).Subsequently, under the condition that gas reduces, the surface of mode cleaning sensor substrate 1, first base plate for packaging 2 and second base plate for packaging 3 by sputter etching is carried out surface activation then and is handled.In other words, first and second metal levels (18 to sensor base plate 1,19), the surface of the metal level (28,29) of the surface of the frame part 11 that engages with second base plate for packaging 3, first base plate for packaging 2 and second base plate for packaging 3 that engages with sensor base plate is carried out surface activation and is handled.Handle as surface activation, the ion beam of giving the surface emissivity argon that will handle is with preset time cycle (for example 300 seconds).In the surface activation processing procedure, the internal pressure of chamber remains on the vacuum degree lower than above-mentioned vacuum degree (for example about 1 * 10 ^-2Pa).The ion beam that replaces argon can use the atomic beam and the plasma of argon.The gas that is used for the surface activation processing is not limited to argon gas.Alternatively, can use inert gas, as nitrogen and helium.

After surface activation is handled, carry out the atmosphere set-up procedure, thereby chamber interior is adjusted into the atmosphere of expecting for the engagement step between in sensor base plate 1 and first and second base plate for packaging (2,3) each, as shown in Figure 13 B.By this step, the inside of each acceleration sensor unit after engagement step (being movable part) all remains in the atmosphere of expectation.For example, in the present embodiment that forms the acceleration sensor unit, chamber interior is controlled to be inert gas atmosphere, the argon gas during as atmospheric pressure, thus improve frequency characteristic and impact resistance by damping.Carry out this atmosphere control by gas introducing valve V1 and the gas drain door V2 that opens and closes chamber.In order to stop the pollution that causes activated surface by contacting, especially preferably in chamber rather than be exposed to the outside and carry out atmosphere set-up procedure and engagement step continuously with extraneous air.

After chamber interior is controlled to be the atmosphere of expectation, as shown in Figure 13 C, the direct joint between the activated surface (Si-Si solid phase joint) of the direct joint between the activated surface (Au-Au solid phase joint) of the wiring layer 29 by applying direct joint, second metal level 19 and first base plate for packaging 2 between the activated surface (Au-Au surface) of metal level 28 that suitable load (for example 300N) forms the first metal layer 18 and first base plate for packaging 2 when the room temperature and the frame part 11 of sensor base plate 1 and second base plate for packaging 3.Thereby, remain under the condition of expectation in the atmosphere in the inside of sensor unit and can obtain at the joint interface place just not have basically the solid phase of residual stress directly to engage.

Because the wafer-class encapsulation structure 100 of present embodiment has that direct between the sensor base plate 1 that forms according to low temperature process (as the room temperature joint method) and first base plate for packaging 2 engages and sensor base plate 1 and second base plate for packaging 3 between direct the joint, so have following advantage, promptly with use heat treatment, carry out the situation of engagement step compares as reflow soldering, (Rx1 is to Rx4 for pressure drag component, Ry1 is to Ry4, and Rz1 is to Rz4) be difficult to the stress influence of being heated.In addition, can reduce the manufacturing process that process temperature and acquisition are simplified.

In addition, when forming sensor base plate 1 by use SOI wafer, and by using the Si wafer to form first and second base plate for packaging (2, during 3) each, the stress that can reduce to cause owing to linear expansion coefficient therebetween is different the stress that produces and caused by the linear expansion coefficient difference in flexible portion 13 is to above-mentioned bridge circuit (Bx, By, the influence of output signal Bz).As a result, make the variation minimum of sensor characteristics.Each substrate can be formed by other semi-conducting material outside the silica removal.

When the wafer-class encapsulation structure 100 that will so obtain is cut into the acceleration sensor unit that is formed on the sensor base plate 1 big or small, can cut sensor base plate 1 and first and second base plate for packaging (2,3) simultaneously, make it have identical external dimensions.Therefore, can effectively obtain the compact chip scale package structure.

Following brief explanation is from the operation of the acceleration sensor device of the wafer-class encapsulation structure acquisition of present embodiment.

Apply under the situation of acceleration for sensor base plate 1, when on " x " axle positive direction, applying acceleration for sensor base plate 1, because weight part 12 acts on the inertia force on " x " axle negative direction, weight part 12 produces displacement with respect to frame part 11.As a result, longitudinal direction is corresponding to " x " axial pair of flexible part 13 strains, thereby the resistance value of the pressure drag component on the flexible portion 13 (Rx1 is to Rx4) changes.In this case, (Rx1 Rx3) receives tensile stress to pressure drag component, and (Rx2 Rx4) receives compression stress to pressure drag component.Usually, when pressure drag component received tensile stress, resistance value (resistivity) increased, and when pressure drag component received compression stress, resistance value (resistivity) reduced.Therefore, in this case, pressure drag component (Rx1, resistance value Rx3) increases, and (Rx2, resistance value Rx4) reduces pressure drag component.(VDD, when applying constant dc voltage between GND), (X1, X2) potential difference between changes according to the amplitude of the acceleration on " x " direction of principal axis the output of the bridge circuit (Bx) shown in Fig. 5 left side when give a pair of input shown in Fig. 5 from external power source.

Similarly, when applying acceleration on " y " direction of principal axis sensor base plate 1, (Y1, Y2) potential difference between changes according to the amplitude of the acceleration on " y " direction of principal axis the output of the bridge circuit By shown in Fig. 5 middle part.In addition, when applying acceleration on " z " direction of principal axis sensor base plate 1, (Z1, Z2) potential difference between changes according to the amplitude of the acceleration on " z " direction of principal axis the output of the bridge circuit Bz shown in Fig. 5 right side.Therefore, (variation of output voltage Bz) can be surveyed the acceleration that is applied to sensor base plate 1 with respect to " x " direction of principal axis, " y " direction of principal axis and " z " axial each direction to sensor base plate 1 for Bx, By by surveying each bridge circuit.In the present embodiment, movable part is made up of weight part 12 and flexible portion 13, and transducing part is formed by the pressure drag component (Rx1 is to Rx4, and Ry1 is to Ry4, and Rz1 is to Rz4) as measuring resistance on the sensor base plate 1.

In passing, as shown in Figure 5, sensor base plate 1 has by three bridge circuit (Bx, By, Bz) shared two inputs (VDD, GND), two output (X1 of bridge circuit Bx, X2), two outputs of bridge circuit By (Y1, Y2) and two outputs of bridge circuit Bz (Z1, Z2).These inputs (VDD, GND) and output (X1, X2, Y1, Y2, Z1 Z2) is formed in the face of on the surface of first base plate for packaging 2 by second metal level 19, and is electrically connected with through hole distribution 24 in being formed on first base plate for packaging 2.In other words, in the present embodiment, second metal level 19 is formed on eight positions on the sensor base plate 1, is formed with eight through hole distributions 24 in first base plate for packaging 2.Each second metal level 19 that is formed on eight positions is configured to rectangular periphery shape (being square peripheral shape in the present embodiment).In addition, second metal level 19 setting that on the peripheral direction of frame part 11, is separated from each other.In the present embodiment, all be provided with a pair of second metal level 19 at each place, limit on four limits of frame part 11 with rectangular shape.

(second execution mode)

As Figure 14 A to as shown in the 14C, except sensor base plate 1 has IC area E 2 except that the acceleration sensor unit, and IC area E 2 comprises pressure drag component with measuring circuit (being transducing part), and (Rx1 is to Rx4, Ry1 is to Ry4, Rz1 is to Rz4) outside the integrated circuit (being CMOS IC) of the use CMOS of cooperating, the wafer-class encapsulation structure of present embodiment is identical with first execution mode roughly.By integrated signal processing circuit be used for the EEPROM that the storage signal treatment circuit uses and form this integrated circuit, described signal processing circuit is configured to the bridge circuit (Bx described in first execution mode, By, Bz) output signal is carried out signal processing, adjusts and temperature-compensating as amplifying, being offset.Therefore, in the explanation below, by identical reference marker represent with first execution mode in identical assembly, will omit it and be repeated in this description.

As shown in Figure 15 A and 15B, the sensor base plate 1 of present embodiment is formed by sensor region E1, the engaging zones E3 that has the IC area E 2 of said integrated circuit and have a first metal layer 18 described in first execution mode, sensor region E1 comprises a part of frame part 11 described in first execution mode, weight part 12, flexible portion 13 and pressure drag component, and (Rx1 is to Rx4, Ry1 is to Ry4, and Rz1 is to Rz4).In plane graph, design these zones (E1, E2, layout E3) so that sensor region E1 is positioned at the approximate centre part of sensor base plate 1, IC area E 2 forms around sensor region E1, engaging zones E3 forms around IC area E 2.The frame part 11 of the sensor base plate 1 of present embodiment has the external dimensions bigger than first execution mode.In other words, because sensor base plate 1 has the frame part 11 that width dimensions increases, so integrated circuit can be installed on the frame part 11.In addition, the recess 21 of first base plate for packaging 2 forms big than first execution mode, thereby sensor region E1 and IC area E 2 are contained in the recess.The sandwich construction part 41 of IC area E 2 described later is arranged in the recess 21.

With the same in the situation of first execution mode, form semiconductor wafer 10 by using the SOI wafer.Preferably form IC area E 2, thereby reduce the area that IC area E 2 occupies on sensor base plate 1 by the multilayer wired technology of use.At the IC of sensor base plate 1 area E 2 places, the stacked film of first dielectric film by the silicon oxide film on the silicon layer 10c and second dielectric film of the silicon nitride film on first dielectric film forms dielectric film 16, and sandwich construction part 41 is formed on the dielectric film 16.Sandwich construction part 41 comprises the 3rd dielectric film of at least one interlayer dielectric (silicon oxide film) and the 4th dielectric film of the passivating film on the 3rd dielectric film (stacked film of silicon oxide film and silicon nitride film).By removing the suitable part of passivating film, expose a plurality of pads 42.Therefore, in the present embodiment, sealer 40 is made up of dielectric film 16 (first and second dielectric films) and sandwich construction part 41 (third and fourth dielectric film).On the other hand, at engaging zones E3 place, second metal level 19 is formed on a plurality of positions on the dielectric film 16.Second metal level 19 is electrically connected with pad 42 by wiring lead 43.As a result, the pad 42 in IC zone 42 is electrically connected with the distribution metal level 29 at the through hole distribution 24 1 end places that are formed on first base plate for packaging 2 by the wiring lead 43 and second metal level 19.Pad 42 is electrically connected with transducing part by signal processing circuit, perhaps is not electrically connected with transducing part by signal processing circuit.

In the sensor base plate 1 of present embodiment, as shown in Figure 15 B, the wiring lead 43 and second metal level 19 are formed by identical materials, and their continuous formation.Alternatively, as shown in Figure 16 A, wiring lead 43 can form separately with second metal level 19.In this case, in order to improve cohesive force, wiring lead 43 is preferably formed by the stacked film of Au film and Ti film.

By the way, when forming sealer 40 on the general surface at SOI substrate 10, in the first area of the pad 42 that is formed with IC area E 2 and be formed with between the second area of second metal level 19 and the first metal layer 28 and step part occurs.Because this step part, need be formed for the wiring lead 43 that between the pad 42 of IC area E 2 and second metal level 19, is electrically connected along the side surface of sealer 40.In the situation of Figure 16 A, the thickness of the thickness of wiring lead 43 and the first metal layer 18 and second metal level 19 is determined separately.For example, the thickness of wiring lead 43 " A " is set at the thickness " B " greater than the first metal layer 18 and second metal level 19.

In addition, as shown in Figure 16 B, the preferred wiring lead 43 and second metal level 19 are whole in a continuous manner to be formed, and the thickness setting of wiring lead 43 is the thickness greater than the first metal layer 18 and second metal level 19.In this case, so carry out film and form, promptly wiring lead 43, the first metal layer 18 and second metal level 19 form the thickness (T1) with wiring lead 43 simultaneously.Subsequently, so carry out the thickness adjustment, i.e. only the etching the first metal layer 18 and second metal level 19, thus have the thickness (T2＜T1) of expectation.As a result, can reduce to take place the possibility of disconnection at the stage portion office of sealer 40 wiring lead 43.

Film at wiring lead 43, the first metal layer 18 and second metal level 19 forms the stage, at first form lower metal layer (for example stacked film of the Au film on Ti film and the Ti film) with thickness T 2, forming metal level (for example stacked film of the Au film on Ti film and the Ti film) on the lower metal layer then, its have and thickness T 1 and thickness T 2 between the corresponding thickness of difference.In the thickness adjusting stage, with the corresponding location of first and second metal levels (18,19) time, engrave metal level as etch stopper by using lower metal layer.Thereby, first and second metal levels (18,19) that can obtain to have thickness T 2.In this case, have following advantage, promptly be easy to control the thickness of first and second metal levels (18,19), and can realize the raising of the surface smoothness of first and second metal levels (18,19).As a result, can improve the productivity ratio of sensor device.

As shown in Figure 16 C, also preferred wiring lead 43 has the double-layer structure of following wiring layer 43a and last wiring layer 43b, and the last wiring layer 43b and second metal level 19 are whole in a continuous manner to be formed.For example, (43a, 43b) stacked film by the Au film on Ti film and the Ti film forms for following wiring layer and last wiring layer.In this case, obtain wiring lead 43 by the operation that comprises the steps: wiring layer 43a under forming on the sealer 40 is forming wiring layer 43b on the wiring layer 43a down.On forming, in the step of wiring layer 43b, form first and second metal levels (18,19) simultaneously.The thickness of wiring lead 43 is defined as equaling wiring layer and last wiring layer (43a, gross thickness 43b) down.Thereby, can improve the productivity ratio in the engagement step between the sensor base plate 1 and first base plate for packaging 2.In addition, by the reliability that is electrically connected between the pad 42 that stops wiring lead 43 to disconnect to realize IC area E 2 and second metal level 19.

Alternatively, wiring layer 43b in the replacement, can with the continuous whole wiring layer 43a down that forms of mode of second metal level 19.In this case, under forming, form first and second metal levels (18,19) simultaneously in the step of wiring layer 43a.Subsequently, only on the zone corresponding, form wiring layer 43b with wiring lead 43.(43a, gross thickness 43b) is determined the thickness of wiring lead 43 by descending wiring layer and last wiring layer.

Next, with reference to Figure 17 A to 17F, the manufacture method of the sensor base plate 1 of explained later present embodiment.Figure 17 A to 17F each all corresponding to cross section along the line A-A ' of Figure 15 A.In addition, use the structure of Figure 16 A as wiring lead 43.

At first, by using CMOS operation technology on the general surface of SOI substrate 10 (surface one side of silicon layer 10c), to be formed for bridge circuit (Bx, By, Bz), (Rx1 is to Rx4 for pressure drag component, Ry1 is to Ry4, Rz1 is to Rz4) and the diffusion layer distribution of IC area E 2, thereby structure described in Figure 17 A obtained.In the stage of the step of having finished the pad 42 that exposes IC area E 2, above-mentioned sandwich construction part 41 is extended on the whole surface of dielectric film 16.Do not form metal wiring in location with sensor region E1 and the corresponding sandwich construction part 41 of engaging zones E3.In the present embodiment, as mentioned above, sealer 40 is made up of dielectric film 16 and sandwich construction part 41.In this stage, sealer 40 does not still have above-mentioned step part.

After the step of having finished exposed pad 42, on the general surface of SOI substrate 10, form the patterning resist layer, so that the zone of exposure and sensor region E1 and the corresponding sealer 40 of engaging zones E3.By using this resist layer, carry out the graduation operation as etching mask.In other words, by the zone of the etchback sealer 40 corresponding, form the flat surfaces of engaging zones E3 with engaging zones E3.Then, remove resist layer, thereby obtain the structure shown in Figure 17 B.When carrying out the etchback step by wet etching, second dielectric film of the silicon nitride film of use dielectric film 16 is as etch stopper.As the result of graduation operation, the above-mentioned step part of sealer 40 has appearred.

Subsequently, be used on the general surface of SOI substrate 10, forming the distribution formation step of wiring lead 43, and on engaging zones E3, form the first metal layer 18 and second metal level 19.For the formation of wiring lead and these metal levels, the preferred film deposition techniques of using routine is as sputter and photoengraving lithography.Next, on dielectric film 16, form the patterning resist layer, make core 12a, flexible portion 13, IC area E 2 and the corresponding zone of engaging zones E3 of its covering and frame part 11, weight part 12, and expose other zones.Subsequently, carry out first composition (patterning) operation.In other words, by using this resist layer as etching mask, the exposed region of etching dielectric film 16, thus carry out the composition of dielectric film 16.Proceed etching, thereby have the etch depth that arrives insulating barrier 10b from a general surperficial side of SOI substrate 10.Then, by removing resist layer, obtained the structure shown in Figure 17 C.In this first composition operation, use insulating barrier 10c as etch stopper.As the result of the first composition operation, the silicon layer 10c of SOI substrate 10 is retained in and frame part 11, core 12a, flexible portion 13, IC area E 2 and the corresponding location of engaging zones E3.As the engraving method that is suitable for the first composition operation, for example, preferably by using inductively coupled plasma (ICP) type device for dry etching to carry out dry ecthing.Etching condition is set, so that insulating barrier 10b is as etch stopper.

After having finished the first composition operation and having removed resist layer, on the silicon oxide film 10d on the supporting substrate 10a that is formed at SOI substrate 10 basal surface sides, form the patterning resist layer, so that it covers and frame part 11, core 12a, the 12b of leaf portion, IC area E 2 and the corresponding zone of engaging zones E3, and expose other zones.Subsequently, carry out the second composition operation.In other words, by using this resist layer as etching mask, the exposed region of etching oxidation silicon fiml 10d, thus carry out the composition of silicon oxide film 10d.After having removed resist layer, on the direction of approximate vertical, carry out dry ecthing by using silicon oxide film 10d as etching mask, thereby have the etch depth that arrives insulating barrier 10d from SOI substrate 10 basal surfaces one side.By this second composition operation, obtained the structure shown in Figure 17 D.In this composition operation, use insulating barrier 10b as etch stopper.After the second composition operation, the supporting substrate 10a of SOI substrate 10 is retained in and frame part 11, core 12a, the 12b of leaf portion, IC area E 2 and the corresponding location of engaging zones E3.As the Etaching device that is suitable for the second composition operation, preferably use inductively coupled plasma (ICP) type device for dry etching.Etching condition is set, so that insulating barrier 10b is as etch stopper.

After the second composition operation, carry out separation circuit.In other words, stay dielectric film 10b with frame part 11, core 12a, IC area E 2 and the corresponding zone of engaging zones E3 in, remove unwanted part by wet etching and form frame part 11, flexible portion 13 and weight part 12.As a result, obtained the structure shown in Figure 17 E.In this separation circuit, also etching and remove silicon oxide film 10d on SOI substrate 10 basal surfaces.

Join the sensor base plate 1 that forms according to above-mentioned operation to by each room temperature, obtained the structure shown in Figure 17 F second base plate for packaging 3 shown in first base plate for packaging 2 shown in Figure 18 A and the 18B and Figure 19 A and the 19B.In other words, by connecing and carry out room temperature between the activated surface (the Au-Au solid phase engages) of the wiring layer 29 that is incorporated in second metal level 19 and first base plate for packaging 2 and engage carrying out room temperature between the activated surface (Au-Au surface) of the first metal layer 18 of sensor base plate 1 and the metal level 28 of first base plate for packaging 2, the sensor base plate 1 and first base plate for packaging 2 integrate.On the other hand, by engaging carrying out room temperature between the frame part 11 of sensor base plate 1 and the activated surface of second base plate for packaging 3 (the Si-Si solid phase engages), the sensor base plate 1 and second base plate for packaging 3 integrate.

By the way, in the present embodiment, by sensor base plate 1 and base plate for packaging (2,3) are carried out Figure 17 A to the series of steps described in the 17F with wafer scale, manufacturing has the wafer-class encapsulation structure 100 (Figure 14 A) of a plurality of acceleration sensors.Then, be cut into the acceleration sensor size by the wafer-class encapsulation structure 100 that will so obtain and cut (stripping and slicing) operation.In this case, each external dimensions of first and second base plate for packaging (2,3) is accurately mated with the external dimensions of sensor base plate 1 simultaneously.Therefore, this manufacture method is particularly suited for making in a large number the compact sensor device.Before cutting action, preferably carry out examination phase, be used to check the electrical characteristics of the transducing part and the circuit part of sensor device.Compare with after single separation sensor device, checking the situation of electrical characteristics, can save the time and efforts of examination phase greatly from the wafer-class encapsulation structure.

According to above-mentioned manufacture method; because the zone of the sealer corresponding with engaging zones E3 40 is by etchback and by graduation; and on the flattened surface of engaging zones E3, be formed for the first metal layer 18 and second metal level 19 that engage with first base plate for packaging 2; so can improve the surface smoothness of first and second metal levels (18,19).Therefore, can be between the metal level 28 of the first metal layer 18 and first base plate for packaging 2 and obtain good solid phase between the wiring layer 29 at second metal level 19 and first base plate for packaging 2 and directly engage.As a result, can boost productivity.

In addition, according to above-mentioned manufacture method, because second dielectric film of the silicon nitride film by using insulating barrier 16 carries out the etchback step as etch stopper, so the available evenness suitable with general surface SOI substrate 10 forms first and second metal levels (18,19) on dielectric film 16.As a result, can improve the surface smoothness of first and second metal levels (18,19).The dielectric film that is used as etch stopper in the graduation operation is not limited to second dielectric film.Can use other dielectric films except that the 4th dielectric film of sandwich construction part 41.Can determine to be used as the dielectric film of etch stopper according to the required height level of engaging zones E3.

Alternatively, by using after second dielectric film carries out etching as etch stopper, can carry out further etching as etch stopper by using first dielectric film.In this case, can the bottom insulating barrier be provided for the first metal layer 18 and second metal level 19 with outstanding surface smoothness by first dielectric film.Preferably form the silicon oxide film that is used as first insulating barrier by thermal oxidation process and LPCVD (low-pressure chemical vapor deposition) method.

In the sensor device of present embodiment because in frame part, constructed have can with the IC chip of the integrated circuit of measuring resistance cooperating, so compare, can reduce the size of sensor device and reduce manufacturing cost with the sensor assembly of routine.In addition, the raising that reduces to bring sensor characteristics of the distribution length between measuring resistance and the integrated circuit.

(the 3rd execution mode)

In the execution mode on each, use the resistance pressure type acceleration sensor as sensor unit.Technological concept of the present invention also is effective for other sensor units as capacitor type acceleration sensor and gyrosensor.Present embodiment is characterised in that and replaces the acceleration sensor unit, form gyro reference unit on sensor base plate.Other structures of present embodiment are identical with first execution mode roughly.Therefore, can form the bonding part at sensor base plate 101 and first and second base plate for packaging (102,103) between each according to the mode identical with first execution mode.

The wafer-class encapsulation structure of present embodiment has following structure, second encapsulated wafer that it comprises one of the semiconductor wafer with a plurality of gyro reference units, the apparent surface's who joins semiconductor wafer to first encapsulated wafer and joins another surface of semiconductor wafer to.In the explanation below, the zone definitions that is used to form each gyro reference unit of semiconductor wafer is a sensor base plate 101.In addition, the zone definitions in the face of each sensor base plate 101 of first encapsulated wafer is first base plate for packaging 102.Similarly, the zone definitions in the face of each sensor base plate 101 of second encapsulated wafer is second base plate for packaging 103.

In the present embodiment, the silicon substrate formation sensor base plate 101 that has 0.2 Ω cm resistivity by use.The silicon substrate that has 20 Ω cm resistivity by use forms each of first and second base plate for packaging (102,103).These resistivity values only are that schematically the present invention is not limited to them.

As shown in Figure 20, gyro reference unit is mainly formed by movable part and detection steps, movable part comprises first mass 111 that can be by vibrating mass vibration and is couple to second mass 112 of first mass 111, and probe portion is configured to second mass 112 that will cause when applying revolving force in first mass, 111 vibration processes displacement conversion is the signal of telecommunication.

In other words, each all roughly has first mass 111 of rectangular periphery shape and second mass 112 and be arranged in parallel along the surface of sensor base plate 101 in plane graph.In addition, sensor base plate 101 has the frame part 110 (for example being the rectangular frame part in the present embodiment) that extends around first and second mass (111,112).In the present embodiment, shown in each right lower quadrant of Figure 20 to 24, the definition orthogonal coordinate system.In other words, the direction that first and second mass (111,112) are set is corresponding to " y " direction of principal axis, in the plane of extending along the plane of sensor base plate 101 with the direction of " y " direction of principal axis quadrature corresponding to " x " direction of principal axis.In addition, with the direction (being the thickness direction of sensor base plate 101) of " x " direction of principal axis and " y " direction of principal axis quadrature corresponding to " z " direction of principal axis.

As shown in Figure 21, first mass 111 of sensor base plate 101 and second mass 112 by a pair of driving spring 113 that on " x " direction of principal axis, extends each other integral body couple.In other words, sensor base plate 101 has on " x " direction of principal axis that length is shorter than the slit groove 114a of second mass, 112 entire length slightly and with two slit groove 114b along the horizontal side that is positioned at first mass 111 of " x " axial straight line setting.Each slit groove 114b has opening at the one end.Each driving spring 113 all is formed between slit groove 114a and each the slit groove 114b.All extend between the transverse edge of the end of slit groove 114a and second mass 112 continuously an end of each driving spring 113, and another end of driving spring 113 extends to first mass 111 continuously by the zone between the slit groove 114b.Driving spring 113 is the torsionsprings with torsional deflection ability, its can make first mass 111 with respect to second mass 112 about driving spring 113 displacements.In other words, driving spring 113 can make first mass 111 with respect to second mass 112 at " z " direction of principal axis top offset and first mass 111 is rotated about " x " axle with respect to second mass 112.In addition, because sensor base plate 101 uses torsionspring as driving spring 113, so needn't reduce the size of driving spring 113 on sensor base plate 101 thickness directions.Therefore, be easy to make driving spring 113.

Digital 115 are illustrated in the detection spring that extends on " y " direction of principal axis and be connected continuously in the marginal portion of second mass 112 on " x " direction of principal axis of one end place and sensor base plate 101.An opposed end of surveying spring 115 is connected with another detection spring 115 continuously by the element 116 that couples that extends on " x " direction of principal axis.In other words, to surveying spring 115 and coupling element 116, in plane graph, form the roughly element of " C " shape by this.For this point, couple element 116 and be designed to have than driving spring 113 and detection spring 115 abundant high rigidity.The standing part that numeral 117 expressions are given prominence to from the mid portion on the longitudinal direction that couples element 116.Standing part 117 is fixed to the precalculated position of second base plate for packaging 103.First and second mass (111,112) by the slit groove 114c that forms with " C " shape roughly with survey spring 115 and couple element 116 and separate.The end of slit groove 114b communicates with slit groove 114c.Each surveys spring 115 all just crooked deformability on " x " direction of principal axis.Therefore, survey spring 115 can make first and second mass (111,112) with respect to standing part 117 at " x " direction of principal axis top offset.

By the way, sensor base plate 101 has four openings 118 that penetrate second mass 112 on thickness direction and is arranged on stationary part 120 in each opening 118.Stationary part 120 has be arranged on second mass 112 near the electrode part 121 each end on " x " direction of principal axis and comb bone (comb bone) part 122 of extending from electrode part 121 on " x " direction of principal axis.Electrode part 121 and comb bone parts 122 constitute roughly " L " shape.Electrode part 121 and comb bone parts 122 join second base plate for packaging 103 to.In other words, stationary part 120 is fixed on the pre-position.The inner surface of opening 118 by the gap along extending on the peripheral surface of stationary part 120.Pair of electrodes part 121 is arranged on the two ends place of second mass 112 on " x " direction of principal axis.As shown in Figure 22, the both sides on the Width of comb bone parts 122 are formed with a plurality of stationary comb-tooth 123 that are provided with along " x " direction of principal axis.On the other hand, side at the comb bone parts 122 of facing second mass 112 is formed with a plurality of mobile broach 124 in opening 118, these a plurality of mobile broach 124 are along the setting of " x " direction of principal axis, are aspectant relations so that each moves broach 124 with each stationary comb-tooth 123, as shown in Figure 22.Each moves broach 124 and leaves corresponding stationary comb-tooth 123 1 distance settings.When second mass 112 was mobile on " x " direction of principal axis, the distance between stationary comb-tooth 123 and the mobile broach 124 changed, thereby surveyed the capacitance variations that is caused by variable in distance.In other words, the exploring block that is used to survey 112 displacements of second mass is made up of stationary comb-tooth 123 and mobile broach 124.

By joining frame part 110, standing part 117 and stationary part 120 to second base plate for packaging 103, sensor base plate 101 is couple to second base plate for packaging 103.In other words, use second base plate for packaging 103 as the supporting substrate that supports sensor base plate 101.On the other hand, because forming, first and second mass (111,112) can on " z " direction of principal axis, move, so first and second mass (111,112) basal surface in the face of second base plate for packaging 103 leaves second base plate for packaging 103 backward, as shown in Figure 20.In other words, each thickness of first and second mass (111,112) is defined as thickness less than frame part 110 on the thickness direction of sensor base plate 101.Thereby, guaranteed in second base plate for packaging 103 and first and second mass (111, the 112) gap between each.In the present embodiment, the gap length between first mass 111 and second base plate for packaging 103 is made as 10 μ m.This value only is that schematically the present invention is not limited to it.

In addition, sensor base plate 101 has a pair of grounded part (ground portion) 119 near the frame part 110 that is formed on the standing part 117.Numeral 127 expressions are electrically connected and are formed near the electrode part of a grounded part 119 with aftermentioned electrode 125.Grounded part 119 and electrode part 127 join second base plate for packaging 103 to.In upper surface side, on standing part 117, electrode part 121, grounded part 119 and electrode part 127, be formed with second metal level 128.For this point, standing part 117, four electrode parts 121, a grounded part 119 and an electrode part 127 are in the setting separated from one another of the upper surface side of second base plate for packaging 103.Do not have in the state of bonded to frame part 110 at first base plate for packaging 102, they are electrically insulated from each other.In addition, in the upper surface side of sensor base plate 101, frame part 110 has and is formed on its whole outer the first metal layer of placing 126.Each is all formed first and second metal levels (126,128) by the stacked film of Ti film and Au film.In brief, because first and second metal levels (126,128) are formed by identical metal material, so thickness that can be identical obtains these metal levels simultaneously.In each of first and second metal levels (126,128), the Ti film preferably has 15 to 50nm thickness, and the Au film preferably has the thickness of 500nm.These one-tenth-value thickness 1/10s only are that schematically the present invention is not limited to them.As the material that forms the Au film, can replace proof gold to use the Au material that comprises impurity.

As shown in Figure 23 and 24, first base plate for packaging 102 is in the side in the face of sensor base plate 101, be to have recess 129 in the basal surface of first base plate for packaging 102 shown in Figure 20, its displacement that is constructed to first and second mass (111,112) provides the space.In addition, first base plate for packaging 102 has a plurality of through holes 132 that penetrate on thickness direction.On the inner surface of two apparent surfaces on first base plate for packaging, 102 thickness directions and through hole 132, be formed with opaque film 133 (silicon oxide film).Therefore, opaque film 133 is between the inner surface of through hole distribution 134 and through hole 132.In the present embodiment, use the material of copper as through hole distribution 134.Alternatively, Alloy instead of Copper can be used nickel etc.

First base plate for packaging 102 has by dielectric film 133 and is formed on the above-mentioned electrode 125 in the face of the location of first mass 111 on the basal surface of recess 129.Electrode 125 is formed by the stacked film of Ti film and Au film.In the present embodiment, the gap length between first mass 111 and the electrode 125 is made as 10 μ m.This value only is that schematically the present invention is not limited to it.

In addition, first base plate for packaging 102 has a plurality of metal levels 138, and these a plurality of metal levels 138 are formed in the face of being electrically connected on the surface of sensor base plate 101 and with through hole distribution 134.First base plate for packaging 102 also has lip-deep whole outer (rectangle) frame-like metal level 136 placed that is formed in the face of sensor base plate 101.In this, metal level 138 joins second metal level 128 of sensor base plate 101 to, thereby is electrically connected betwixt.Metal level 136 joins the first metal layer 126 of sensor base plate 101 to.Each is all formed metal level 136 and metal level 138 by the stacked film of Ti film on the dielectric film 133 and the Au film on the Ti film.In brief, because metal level 136 is formed by identical metal material with metal level 138, so thickness that can be identical obtains these films simultaneously.In each of metal level 136 and metal level 138, the Ti film preferably has 15 to 50nm thickness, and the Au film preferably has the thickness of 500nm.These one-tenth-value thickness 1/10s only are that schematically present embodiment is not limited to them.As the material of Au film, replace proof gold can use the material that comprises impurity based on Au.In addition, in the present embodiment, the Ti film forms the tack coat that is used to improve the cohesive force between Au film and the dielectric film 133.Replace Ti, can use Cr, Nb, Zr, TiN, TaN etc. are as the material of tack coat.

First base plate for packaging 102 have be formed on in the face of the outside a plurality of electrodes 135 that are connected that are used on the surperficial facing surfaces of sensor base plate 101.These electrodes 135 are electrically connected with through hole distribution 134.Each electrode 135 all is configured to the rectangular periphery shape and is formed by the stacked film of Ti film and Au film.

On the other hand, second base plate for packaging 103 has the opaque film (141,142) on two apparent surfaces that are formed on its thickness direction, as silicon oxide film.

The same with described in first execution mode, sensor base plate 101 directly engage by the first metal layer 126 and solid phase between the metal level 136 and join first base plate for packaging 102 to.In other words, first base plate for packaging 102 joins the whole periphery of the frame part 110 of sensor base plate 101 hermetically to.In addition, second metal level 128 directly engages with metal level 138 by solid phase and is electrically connected.Directly engage by these solid phases, the inside and the outside of gyro reference unit seal airtightly.In addition, second metal level 128 of sensor base plate 101 is electrically connected with electrode 135 by metal level 138 and through hole distribution 134.Second base plate for packaging 102 has the distribution part 125a (Figure 24) that extends to recess 129 peripheries from electrode 125, and it forms continuously with the metal level 138 that joins second metal level 128 on the electrode part 127 of sensor base plate 101 to.

In order to form the bonding part between each, use the room temperature joint method that when low temperature, forms direct joint, to reduce the residual stress in the sensor base plate 101 at sensor base plate 101 and first and second base plate for packaging (102,103).In the room temperature joint method, ion beam, atomic beam or the plasma clean by radiation argon in a vacuum also activates the surface that will engage, then the surface that will activate when room temperature in a vacuum direct joint each other.In the present embodiment, according to above-mentioned room temperature joint method, by apply in a vacuum that suitable load obtains simultaneously that direct between the first metal layer 126 and the metal level 136 engages when the room temperature to joint interface and second metal level 128 and metal level 138 between direct the joint.In addition, in the mode of sealing the frame part 110 of transducer is directly joined to the periphery of second base plate for packaging 103 in a vacuum when the room temperature by the room temperature joint method.

The room temperature joint method of explained later present embodiment.Omit repetition of explanation with first execution mode same steps as.

Sensor base plate 101 is suitably being carried out little processing and after room temperature joins sensor base plate 101 to second base plate for packaging 103, be used for etching step that the part that is used as the movable part of sensor base plate 101 is separated with other parts and the metal level that is used to form first and second metal levels (126,128) formation step.In the present embodiment, sensor base plate 101 is by Si and SiO ₂Between room temperature engage and join second base plate for packaging 103 to.Subsequently, the sensor base plate 101 that is integrated with second base plate for packaging 103 and first base plate for packaging 102 is placed in the chamber, this chamber is to be discharged to predetermined vacuum level (for example 1 * 10 ^-5) vacuum.Then, carrying out surface activation handles.In other words, clean by the mode of sputter etching in a vacuum and the surface that will be engaged with each other of activated sensors substrate 101 and first base plate for packaging 102.Vacuum degree in surface activation processing procedure middle chamber is approximately 1 * 10 ^-2Pa compares with the predetermined vacuum level in the chamber before surface activation is handled, and this vacuum degree is lower.

After surface activation is handled, carry out the atmosphere set-up procedure, thereby the internal atmosphere that will wherein be placed with the chamber of the sensor base plate 101 and second base plate for packaging 103 is adjusted into the design atmosphere of determining according to the gyrosensor characteristic.At that point, in order to improve near expression other mechanical q-value of mechanical oscillation level (mechanical quality factor Qm) the resonance frequency, and improve sensitivity, the vacuum degree (1 * 10 that the gyrosensor of present embodiment is designed to be scheduled to ^-4Pa or littler high vacuum).In the atmosphere set-up procedure of present embodiment, after finishing the surface activation processing, reached predetermined vacuum degree by carrying out the vacuum degree of vacuum suction in chamber, thereby the internal atmosphere of chamber has been adjusted into the atmosphere of design.

After having finished the atmosphere set-up procedure, join sensor base plate 101 to first base plate for packaging 102 in room temperature under the atmosphere of in the atmosphere set-up procedure, controlling.Engagement step place between the sensor base plate 101 and first base plate for packaging 102 is by applying that suitable load (for example 300N) obtains simultaneously that the first metal layer 126 engages with room temperature between the metal level 136 and second metal level 128 engages with room temperature between the metal level 138.In the present embodiment, engage by the room temperature between Au and the Au engaging between sensor base plate 101 and first base plate for packaging 102 is provided.

Preferably continuous surface activates processing, atmosphere set-up procedure and engagement step in same chamber.Handle the surface that will be engaged with each other of cleaning and the activated sensors substrate 101 and first base plate for packaging 102 by surface activation.Then, the surface in these activation that are engaged with each other during in room temperature in the mode of sealing according to the sensor characteristics wanted and under definite design atmosphere is not exposed to extraneous air.Obtain good joint thus betwixt.In the atmosphere set-up procedure, because chamber is the vacuum that is discharged to predetermined vacuum level after the surface activation treatment step, thereby internal atmosphere is adjusted into the atmosphere of design, so can obtain to represent therefore can improve sensitivity as near other the higher mechanical q-value (mechanical quality factor Qm) of mechanical oscillation level the resonance frequency of the gyrosensor of sensor element.

As mentioned above, the wafer-class encapsulation structure of present embodiment has according to low temperature process, direct between the sensor base plate 101 that forms as the room temperature joint method and first base plate for packaging 102 engage and sensor base plate 101 and second base plate for packaging 103 between direct the joint.Therefore, and by heat treatment, the situation of sensor base plate 101 and each joint of first and second base plate for packaging (102,103) is compared, can be stoped the influence of thermal stress as reflow soldering.As a result, have sensor characteristics and change the advantage that reduces.In addition, because sensor base plate 101 joins second base plate for packaging 103 to by dielectric film 141, can stop reducing to the electrical noise impedance.In addition, because substrate is formed by silicon wafer, and dielectric film 141 forms by silicon oxide film, so sensor base plate 101 is easy to join to each base plate for packaging (102,103) when room temperature, and can reduce the variation of sensor characteristics.

In this preferred implementation, second base plate for packaging 102 joins sensor base plate 101 to by the lip-deep dielectric film 141 in the face of sensor base plate 101 that is formed on second base plate for packaging 103.In brief, preferably they are engaged with each other by the dielectric film that is formed on second base plate for packaging 103 in the face of in the surface of second base plate for packaging 103 at least one in the face of the surface of sensor base plate 101 and sensor base plate 101.

In addition, the wafer-class encapsulation structure cuts (stripping and slicing) of the gyro reference unit by will having integrated formation is the size of gyro reference unit, can be easily and obtain compact gyrosensor device effectively.Therefore be suitable for large-scale production.

The operation of the gyrosensor that following brief explanation so obtains.

When applying under the condition of predetermined vibration for first mass 111, when applying angular speed by external force to gyrosensor, the gyrosensor of present embodiment is surveyed the displacement of second mass 112.At that point, between the electrode 125 and first mass 111, apply vibration voltage, thereby make 111 vibrations of first mass with sinusoidal waveform or square waveform.For example, use AC voltage, but polarity inversion is not necessary as vibration voltage.First mass 111 by driving spring 113, second mass 112, survey spring 115 and couple element 116 and be electrically connected with standing part 117.Second metal level 128 is formed on this standing part 117.In addition, electrode 125 is electrically connected with second metal level 128 on the electrode part 127.Therefore, when applying vibration voltage between second metal level 128 on standing part 117 and electrode part 127, because the electrostatic force between first mass 111 and the electrode 125, first mass 111 can be vibrated on " z " direction of principal axis.When the frequency of vibration voltage equals according to the weight and the driving spring 113 of first and second mass (111,112) and surveys the resonance frequency that the spring constant of spring 115 determines, can be by the bigger amplitude of relative small driving force acquisition.

In the state of first mass, 111 vibrations, when applying angular speed to gyrosensor about " y " axle, on " x " direction of principal axis, produce Coriolis force, thus second mass 112 (with first mass 111) with respect to stationary part 120 at " x " direction of principal axis top offset.When mobile broach 124 during, between mobile broach 124 and stationary comb-tooth 123, produce variable in distance, thereby electric capacity therebetween changes with respect to stationary comb-tooth 123 displacements.Can obtain this capacitance variations from second metal level 128 that is connected with the 4th stationary part 120.Thereby, can think that above-mentioned gyrosensor is provided with the capacitor of four variable capacitances.Therefore, the total capacitance of the capacitor of the electric capacity of capacitor that can be by measuring each variable capacitance or variable capacitance in parallel is surveyed the displacement of second mass 112.Because pre-determine the vibration of first mass 111, so, can calculate Coriolis force by surveying the displacement of second mass 112.In the present embodiment, be arranged on movable part in the frame part 110 by first mass 111, driving spring 113, second mass 112, survey spring 115 and couple element 116 and form, transducing part is made up of the stationary comb-tooth 123 and the mobile broach 124 that are formed on second mass 112.In brief, be formed with a part of transducing part in the movable part in being arranged at frame part 110.

At that point, the displacement of mobile broach 124 is proportional with (weight of first mass 111)/(weight of the weight of first mass 111+second mass 112).Therefore, when the weight of first mass 111 became weight greater than second mass 112, the displacement of mobile broach 124 increased.As a result, can improve sensitivity.In the present embodiment, owing to this reason, the gauge of first mass 111 is defined as the gauge greater than second mass 112.

Industrial applicibility

As mentioned above, according to the present invention, because be formed on surface activation zone on the sensor base plate And be formed between the surface activation zone on each base plate for packaging directly be bonded on room temperature the time form, So can avoid some troubles, the sensor characteristics that causes such as the residual stress by the office, junction surface becomes Change. In addition, the inside of sensor device is direct by the solid phase that does not have diffusion between the surface activation zone Engage airtightly sealing. Therefore, can be according to the kind of sensor, such as acceleration sensor and gyro sensing Device is realized suitable atmosphere in sensor device. The present invention with above-mentioned advantage wishes to be used in needs In the widely various application of the compact sensor device of stability sensor characteristic.

Claims (25)

1, a kind of sensor device comprises:

Sensor base plate, this sensor base plate comprise framework with opening, remain on the movable part in the described opening and be configured to probe portion according to the displacement output signal of telecommunication of described movable part movably;

Join one of the apparent surface's of described sensor base plate first base plate for packaging to;

Join second base plate for packaging on another surface of described sensor base plate to;

Wherein said framework has first surface active region and second surface active region, this first surface active region is formed on whole outer the facing on the surface of first base plate for packaging of placing of described framework, so that described first surface active region surrounds described movable part, described second surface active region is formed on whole outer the facing on the surface of second base plate for packaging of placing of described framework, so that described second surface active region surrounds described movable part

Engaging between described sensor base plate and first base plate for packaging be described first surface active region be formed on first base plate for packaging on the surface activation zone between do not have the solid phase of diffusion directly to engage,

Engaging between described sensor base plate and second base plate for packaging be described second surface active region be formed on second base plate for packaging on the surface activation zone between do not have the solid phase of diffusion directly to engage.

2. sensor device according to claim 1, any one in the surface of the surface that the surface activation of wherein said first surface active region, described second surface active region, first base plate for packaging surface activation zone regional and second base plate for packaging is a plasma treatment, the surface of ion beam irradiation and atomic beam radiation.

3. to be Si directly engage with solid phase between the Si at least one in the engaging between the surface activation zone on the sensor device according to claim 1, joint between the surface activation zone on the wherein said first surface active region and first base plate for packaging and described second surface active region and second base plate for packaging, Si and SiO ₂Between solid phase directly engage and SiO ₂With SiO ₂Between solid phase any one in directly engaging.

4. to be Au directly engage with solid phase between the Au at least one in the engaging between the surface activation zone on the sensor device according to claim 1, joint between the surface activation zone on the wherein said first surface active region and first base plate for packaging and described second surface active region and second base plate for packaging, Cu directly engages with solid phase between the Cu and Al and during solid phase between the Al directly engages any one.

5. sensor device according to claim 1, at least one in wherein said first surface active region and the described second surface active region comprise that be formed on described framework whole outer placed with the inboard of the outer annular surface active region that surrounds described movable part and the above outer surface active region of whole periphery of being formed on described framework and sentence the annular inside surface active region that surrounds described movable part.

6. sensor device according to claim 5, further comprise being used for the auxiliary seal zone that is connected between described outer surface active region and described inner surface active region, wherein said auxiliary seal zone is formed on a plurality of positions of the preset distance that is spaced apart from each other on the peripheral direction of described framework.

7. sensor device according to claim 1, each in the described first surface active region of wherein said sensor base plate and the surface activation zone of first base plate for packaging all is the activated surface with Au film of 500nm or littler thickness.

8. sensor device according to claim 1, wherein said sensor base plate have can with the integrated circuit of described probe portion cooperating, described integrated circuit is near the described opening setting of described framework, and is connected with through hole wired electric in being formed on first base plate for packaging.

9. sensor device according to claim 8, wherein said integrated circuit are arranged to surround the described opening of described framework.

10. sensor device according to claim 8, wherein said through hole distribution forms taper in first base plate for packaging, have the area bigger than the other end so that face the end of described sensor base plate.

11. sensor device according to claim 1 wherein is equipped with acceleration sensor on described sensor base plate,

Described movable part comprises weight and the beam part of extending between described framework and described weight, and

Described probe portion comprises at least one pressure drag component that is formed on the described beam part.

12. sensor device according to claim 11, wherein said sensor base plate forms by using the SOI substrate, and described SOI substrate has across insulating barrier and is positioned at silicon layer on the silicon substrate.

13. sensor device according to claim 12, wherein said sensor base plate have can with the integrated circuit of described probe portion cooperating, described pressure drag component and described integrated circuit are formed on the silicon layer of described SOI substrate.

14. sensor device according to claim 1 wherein is equipped with gyrosensor on described sensor base plate,

Described movable part comprises first mass of vibrating by vibrating mass and second mass that couples with first mass, and

The displacement conversion that described probe portion is configured to second mass that causes when applying revolving force in the first mass vibration processes is the signal of telecommunication.

15. having, sensor device according to claim 1, wherein said sensor base plate be formed on than the position of the more close described movable part of described first surface active region and the conductor layer that is electrically connected with described probe portion,

First base plate for packaging has through hole distribution and the wiring layer that is connected with described through hole wired electric,

There is not the solid phase of diffusion directly to engage between the activated surface that engaging between first base plate for packaging and the described sensor base plate further is included in described conductor layer and the activated surface of described wiring layer.

16. a method of making sensor device comprises the steps:

Sensor base plate is provided, joins one of apparent surface's first base plate for packaging of described sensor base plate and second base plate for packaging that joins another surface of described sensor base plate to, described sensor base plate comprises framework with opening, remains on the movable part in the described opening and be configured to probe portion according to the displacement output signal of telecommunication of described movable part movably;

Outside described framework whole, place in the face of forming the first surface active region on the framework surface of first base plate for packaging, so that the first surface active region surrounds described movable part;

Outside described framework whole, place in the face of forming the second surface active region on the framework surface of second base plate for packaging, so that the second surface active region surrounds described movable part;

On each of first base plate for packaging and second base plate for packaging, all form the surface activation zone; With

In room temperature, between the described surface activation zone of described first surface active region and first base plate for packaging, form and directly engage, between the described surface activation zone of described second surface active region and second base plate for packaging, form and directly engage.

17. method according to claim 16 wherein forms the surface activation zone of described first surface active region, described second surface active region, first base plate for packaging and the surface activation zone of second base plate for packaging by in the atomic beam, ion beam and the plasma that use inert gas any one.

18. method according to claim 16, wherein in identical chamber, form described first surface active region and described second surface active region step, form each the step and the direct integrating step in surface activation zone of first base plate for packaging and second base plate for packaging, the inside of described chamber is controlled as the atmosphere of expectation before direct engagement step.

19. method according to claim 16, second metal level that wherein said sensor base plate comprises the wiring lead layer that can be connected with the pad of described integrated circuit with the integrated circuit of described probe portion cooperating, at the one end, it is that the first metal layer of described first surface active region is connected with the other end with described wiring lead layer to be used to provide and be used for being connected with the through hole distribution

First base plate for packaging comprises described through hole distribution, by being formed in the face of the jointing metal layer of the position of described the first metal layer with by being formed on the distribution metal level of described through hole distribution in the face of the place, end of described sensor base plate with the described second metal level identical materials with described the first metal layer identical materials

In room temperature, form the direct joint between the activated surface of the activated surface of direct joint between the activated surface of the activated surface of described the first metal layer and described jointing metal layer and described second metal level and described distribution metal level simultaneously.

20. method according to claim 19 wherein forms described wiring lead layer, described the first metal layer and described second metal level by the operation that comprises the steps:

Formation is as the lower metal layer of etch stopper;

By using the metal material different forming metal level on the described lower metal layer with described lower metal layer; With

The described metal level of going up of the etching location corresponding with described the first metal layer and described second metal level only is up to exposing described lower metal layer.

21. method according to claim 16 wherein forms described first surface active region by the operation that comprises the steps:

On the described framework of described sensor base plate, form multilayer insulating film;

Form the flat surfaces of described multilayer insulating film by the described multilayer insulating film of an etchback part;

On described flat surfaces, form metal level; With

Atomic beam, ion beam or plasma to the surface emissivity inert gas of described metal level.

22. method according to claim 21, wherein said multilayer insulating film comprise the silicon oxide film that is formed on the described framework first dielectric film, be formed on the silicon nitride film on described first dielectric film second dielectric film, be formed on the 3rd dielectric film of at least one interlayer dielectric on described second dielectric film and be formed on the passivating film on described the 3rd dielectric film the 4th dielectric film and

Carry out etchback by use other dielectric films except that described the 4th dielectric film as etch stopper and form described flat surfaces.

23. method according to claim 22 is wherein carried out etchback by the silicon nitride film that uses described second dielectric film as described etch stopper.

24. method according to claim 22 wherein forms described flat surfaces by the operation that comprises the steps:

Use the first etchback step of the silicon nitride film of described second dielectric film as etch stopper: and

The silicon oxide film that passes through described first dielectric film of use that carries out after the first etchback step is as the second etchback step of etch stopper.

25. method according to claim 16, wherein said sensor base plate comprises can be with the integrated circuit of described probe portion cooperating, be formed on the conductor layer position and that be electrically connected with described integrated circuit than the more close described movable part of described first surface active region

First base plate for packaging has through hole distribution and the wiring layer that is connected with described through hole wired electric,

In room temperature, form simultaneously that direct between the surface activation zone of described first surface active region and first base plate for packaging engages and the activated surface of the activated surface of described conductor layer and described wiring layer between direct joint.

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