JP2007237038A - Complex substrate with internal space - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a complex substrate in which a sensor circuit and an outer electrode, which are arranged in the internal space of the complex substrate obtained by directly connecting a pair of substrates each other, are easily connected by a metal wiring, are also excellent in the sealing property of the internal space and are easy in production. <P>SOLUTION: A concave part 2 for the internal space has a first substrate 1 finely processed on the surface and a second substrate 11 which is directly connected to the surface of the first substrate 1 so that the concave part 2 for the internal space is sealed to form the internal space 5. On the surface of the second substrate 11, the metal wiring 13 for electrically connecting the sensor circuit arranged in the internal space and the outer electrode 14 arranged at the outer part of the sensor circuit and the first substrate 1, is laminatedly formed. A wiring concave part 7 containing the metal wiring 13 is formed on the first substrate 1 and the wiring concave part 7, where the metal wiring 13 has been contained, is sealed by a cured resin R. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a composite substrate having one substrate in which a recess is microfabricated and the other substrate directly bonded to the substrate so as to seal the recess and form an internal space. Used for microreactor devices.

  A composite substrate having a recess of about several tens to several hundreds of μm formed on the surface of the first substrate by microfabrication, a second substrate bonded to the surface of the recess of the substrate, and the recess serving as an internal space. Devices equipped are known. For example, in Japanese Patent Application Laid-Open No. 2001-56286 (Patent Document 1), two substrates are bonded using a silicon oxide film, a recess formed in one substrate is closed to form an internal space, and a liquid sample is added thereto. Describes a measurement cell in which a sample introduction port for introducing liquid and a discharge port for discharging a liquid sample are provided, and a partial region of the internal space is used as a measurement chamber. Japanese Patent Laying-Open No. 2005-186033 (Patent Document 2) forms a micro flow path on one substrate and bonds the other substrate to the flow path forming surface of the substrate so as to seal the flow path. A microreactor chip is described.

As the bonding between the substrates, direct bonding, such as anodic bonding or hydrofluoric acid bonding, which is bonded by the bonding force of the substrates themselves is applied. This is because bonding with an adhesive has the following problems and is not suitable as a substrate bonding method in a device structure having a fine internal space. In other words, when the substrates are bonded with an adhesive, the adhesive protrudes over a wide range into the sealed internal space, and the uniformity of the space is lost, or in some cases, a part of the internal space is filled with the adhesive. is there. In addition, since a relatively thick adhesive layer is formed on the joint surface and exposed to the outside at the side edge of the substrate, there is a problem in terms of chemical resistance. For this reason, when bonding is performed using a substrate such as quartz, glass, or silicon, a direct bonding method such as anodic bonding or hydrofluoric acid bonding is often used. With direct bonding, good bonding strength can be obtained for bonding between flat surfaces, and problems such as bonding with an adhesive do not occur.
JP 2001-56286 A Japanese Patent Laid-Open No. 2005-186033

  Some devices require a sensor circuit such as a wiring structure having a detection function in an internal space. In such a device, it is necessary to draw out a sensor circuit provided in the internal space to the external electrode by metal wiring.

  As a method for drawing out the metal wiring, a method is conceivable in which a through hole communicating with the internal space is provided in the substrate, and a sensor circuit installed in the internal space is connected to the external electrode through a conductive member embedded in the through hole. In fact, such a connection method is implemented in a case having a sufficiently large space so that the end opening of the through hole can be accommodated in the internal space.

However, it is difficult to carry out dimensionally to provide a metal wiring by opening a through hole for drawing out a wiring in a minute space having a width of several tens to several hundreds μm such as a microchannel. That is, it is necessary to provide the through hole so as to open directly into the internal space in the device. However, when the through hole is formed by mechanical processing, the internal structure is greatly affected, and the fine structure around the hole is damaged. There is a high risk. Further, even if silicon or the like forming the substrate is dissolved in hydrofluoric acid to form the through hole, a long etching time is required, and the influence on the fine structure around the hole due to the etching is unavoidable. In addition, metal wiring can be formed by applying metal plating to the wall surface of the through hole. It is not easy to hermetically close the micropores.
The present invention has been made in view of such a problem, and a sensor circuit provided in an internal space of a composite substrate in which a pair of substrates are directly bonded to each other and an external electrode are easily connected by metal wiring, and the internal space. An object of the present invention is to provide a composite substrate that is excellent in sealing performance and easy to manufacture.

  The first composite substrate according to the present invention includes a first substrate having a recess for an internal space finely processed on the surface, and a surface of the first substrate so as to form the internal space by sealing the recess for the internal space. A second substrate directly bonded to the sensor, and a sensor circuit disposed in the internal space, and the sensor circuit and an external electrode disposed outside are electrically connected to the surface of the second substrate. The metal wiring to be connected is formed in a laminated manner, the metal wiring is sandwiched between the joint surfaces of the first substrate and the second substrate, and the gap in the width direction end of the metal wiring generated thereby is sealed with a cured resin. It is a thing.

  According to this composite substrate, since the metal wiring is formed together with the sensor circuit on the surface of the second substrate, it is very easy to form a very thin metal wiring itself. Furthermore, if the metal wiring is extremely thin, the first and second substrates can be deformed while sandwiching the metal wiring, and can be directly joined in the region excluding the metal wiring and the vicinity thereof. For this reason, it is very easy to arrange and form the metal wiring without hindering direct bonding between the substrates. In addition, since the gap generated at the end in the width direction by sandwiching the metal wiring is sealed with the cured resin, the communication between the internal space and the outside by the gap is easily blocked, and the internal space is excellent in sealing performance.

In the composite substrate, a resin supply hole for supplying the uncured resin before curing of the cured resin to the gap can be provided in the first substrate.
By providing this resin supply hole and bonding the first substrate and the second substrate and then supplying the uncured resin here, the uncured resin can be easily filled in the gap formed at the end in the width direction of the metal wiring The gap can be easily sealed by curing the gap.

  Further, the second composite substrate of the present invention includes a first substrate having a concave portion for internal space finely processed on a surface thereof, and the first substrate so as to form the internal space by sealing the concave portion for internal space. A second substrate directly bonded to the surface, and a sensor circuit disposed in the internal space, and the sensor circuit and an external electrode disposed outside are electrically connected to the surface of the second substrate. A metal wiring to be connected to the wiring is formed on the first substrate or the second substrate, and a wiring concave portion for accommodating the metal wiring is formed on the first substrate or the second substrate, and the wiring concave portion for accommodating the metal wiring is sealed with a cured resin. It is a thing.

  When the metal wiring is sandwiched between the substrates without providing the wiring recess as in the first composite substrate, the substrates are directly bonded to each other in a state where stress is generated on the substrates. Further, the gap formed at both ends in the width direction of the metal wiring is gradually narrowed from the end of the metal wiring, and the substrates come into close contact with each other. For this reason, the unjoined region of the gap formed at the end in the width direction of the metal wiring is not fixed and covers a relatively wide range. On the other hand, according to the second composite substrate, the metal wiring is accommodated in the wiring recess formed in the substrate, and the wiring recess is sealed with the cured resin in that state, so that no stress is applied to the substrate. Since the unbonded region is limited to the width of the wiring recess, sealing of the wiring recess with the cured resin becomes easier.

  Also in the second composite substrate, similarly to the first composite substrate, an uncured resin after bonding the substrates is provided by providing a resin supply hole for supplying uncured resin before curing of the cured resin to the wiring recess. Can be easily supplied to and filled in the wiring recesses.

In the second composite substrate, the inner circumferential surface of the wiring recess and the inner circumferential surface of the inner space recess are bent at the opening end of the wiring recess where the wiring recess opens into the inner space. It can be.
Since the opening end of the wiring recess opening in the internal space is bent, when the uncured resin supplied to the wiring recess penetrates to the opening end of the wiring recess, the contact angle changes suddenly due to the bending of the flow path. Stop here for a certain time. By curing the uncured resin in the meantime, sealing with the cured resin can be performed at the opening end of the wiring recess. For this reason, the cured resin flows out from the opening of the wiring recess to the inner surface of the recess for the internal space, and the cured resin hardens in a bulging shape at the opening end, or the penetration of the uncured resin stops before the opening end and cures there. By doing so, it is possible to prevent the opening end from being recessed, and as a result, it is possible to improve the surface uniformity and the inner surface quality of the inner surface of the inner space recess.

Further, in the second composite substrate, the contact angle between the uncured resin that is the origin of the cured resin and the inner surface of the wiring recess is increased on the inner peripheral surface near the opening end of the wiring recess in which the wiring recess opens into the internal space. A wettability-reducing film can be formed.
By forming such a wettability-reducing film on the inner peripheral surface in the vicinity of the opening end of the wiring recess, the penetration of the uncured resin stops at the opening end of the wiring recess and is cured in that state. The uniformity of the inner peripheral surface of the recess can be improved, and the quality of the composite substrate can be improved. By making the opening end of the wiring recess into a bent shape and forming a wettable hardened layer, the surface uniformity at the opening end of the wiring recess can be made more reliable.

  According to the composite substrate of the present invention, the metal wiring that connects the sensor circuit disposed in the internal space and the external electrode is sandwiched between the first substrate and the second substrate, and the gap formed at the end in the width direction Is sealed with a curable resin, or a wiring recess is formed in the first substrate or the second substrate, and the wiring recess containing the metal wiring is sealed with a curable resin. It is easy to stop and the composite substrate can be easily manufactured.

Hereinafter, a composite substrate according to an embodiment of the present invention will be described together with a manufacturing method thereof with reference to the drawings.
FIGS. 1 to 3 show a composite substrate according to the first embodiment. The composite substrate is made of quartz, and a first substrate 1 in which a recess 2 for internal space is finely processed on the surface, silicon is used, and the internal And a second substrate 11 directly bonded to the surface of the first substrate 1 so as to seal the space recess 2 to form an internal space 5.

The second substrate 11 has a thermally oxidized SiO ₂ film on its surface, and connects the sensor circuit 12, the external electrode 14 disposed on the outer periphery, and the sensor circuit 12 and the external electrode 14. The metal wiring 13 is laminated by a technique such as photolithography. The sensor circuit 12 is disposed so as to be disposed in the internal space 5. The metal wiring 13 is formed to have a width of, for example, about 50 to 200 μm, and the thickness thereof is extremely thin, for example, about 10 nm to 1 μm, preferably about 10 to 100 nm.

On the other hand, the first substrate 1 is provided with the recess 2 for internal space, and the sample supply hole 4A and the sample discharge hole 4B penetrating into the recess are formed at both ends thereof. The size of the recess 2 for the internal space depends on the application, but for example, the width is about 500 to 1000 μm and the depth is about 200 μm.
The first substrate 1 is opened so as to include a part of the metal wiring 13 and a gap 6 formed at both ends in the width direction in a state where the first substrate 1 is bonded to the second substrate 11. A resin supply hole 3 having a diameter of about 1 mm is formed by machining. When the resin supply hole 3 is processed, it is preferable to process the bonding surface from the bonding surface side after protecting the bonding surface with a resin sheet so as not to damage the bonding surface.

  The first substrate 1 is overlapped with the second substrate 11 so that the opening of the recess 2 for the internal space covers the sensor circuit 12 laminated on the second substrate 11 and sandwiches the metal wiring 13. In addition, direct bonding is performed by a method such as hydrofluoric acid bonding or anodic bonding. For example, hydrofluoric acid bonding is performed by surface-treating the bonding surfaces of the two substrates with 0.1% hydrofluoric acid, aligning them, and holding them at a pressure of about 3 kP for about 24 hours.

  As a result of joining the first substrate 1 and the second substrate 11, the recess 2 for the internal space becomes an internal space 5, and in the substrate portion where the metal wiring 13 is sandwiched, as shown in FIG. The substrate 1 is deformed, and a gap 6 is formed along the metal wiring 13 at both ends of the metal wiring 13 in the width direction, the gap 6 being gradually narrowed in the width direction. The gap 6 has a length in the width direction of about 50 μm when the thickness of the metal wiring is about 20 nm. The metal wiring 13 drawn out from the sensor circuit 12 is disposed at a position away from the sensor circuit 12 so as not to affect the sensor circuit 12 in order to reduce the influence of the gap 6 opened in the inner peripheral surface of the inner space recess 2. It is preferable.

  The metal wiring 13 and the gap 6 at both ends thereof are filled with the cured resin R around the resin supply hole 3 and the lower opening on the metal wiring side, and the gap 6 is sealed. The cured resin R was supplied directly from the resin supply hole 3 after the first substrate 1 and the second substrate 11 were directly joined, and the uncured resin was generated at both ends in the width direction of the metal wiring 13. It has penetrated and filled in the gap 6 so as to fill it. Before the uncured resin is infiltrated, the gap 6 forms a communication space that communicates the internal space 5 with the outside. However, the communication of the communication space is blocked by the infiltration, filling, and curing treatment of the uncured resin. The internal space 5 is sealed. Note that the upper surface of the metal wiring 13 is sandwiched between the first substrates 1 and normally no gap is formed. However, even if a slight gap is generated, the uncured resin penetrates into the upper surface of the metal wiring and the upper surface of the metal wiring. Are also bonded to the bonding surface of the first substrate.

  The sealing region by filling the curable resin does not have to be performed in the entire section of the metal wiring 13 sandwiched between the substrates, and may be a part of the section. However, as shown in FIG. About the 5 side, it is preferable to fill to the boundary which the clearance gap 6 opens to the internal space 5. FIG. Since the joint surface of the substrate 1 forming the gap 6 and the inner surface of the inner space recess 2 are bent at the opening portion of the inner space 5, the uncured resin hardly flows into the inner space 5, Stop at the part. For this reason, the cured resin can be easily filled up to the opening boundary by curing the uncured resin in that state. As a result, the outer peripheral surface of the internal space 5 (the inner surface of the internal space recess 2) is flush, and the measurement accuracy of the fluid sample is improved. However, since the cross section of the gap 6 is very small, even if the gap 6 is opened in the internal space 5, the influence is slight. In the middle portion of the metal wiring 13 in the length direction, the gap 6 is made of cured resin. It may only be sealed.

  Examples of the cured resin R include those obtained by curing (solidifying) PDMS (polydimethylsiloxane), those obtained by irradiating an ultraviolet curable resin with ultraviolet rays, and those obtained by UV-bonding silicone oil. The kind of curable resin to be used is preferably one having good wettability between the uncured resin liquid before curing and the substrate. For example, as in this embodiment, when the substrate material is glass, quartz, silicon or the like, a hydrophilic uncured resin such as an ultraviolet curable resin is easily adapted, and when PDMS or a resin-based substrate is used, it is hydrophobic. Hardened resin is easy to get used to.

  Further, in order to promote the penetration of the uncured resin into the gap 6, the surface of the infiltrating portion of the substrate is improved so as to improve the wettability between the uncured resin liquid and the substrate in advance on the surface of the substrate through which the uncured resin penetrates. It is advisable to apply hydrophilic or hydrophobic treatment to the surface. For example, when a hydrophilic UV curable resin is used, the hydrophilicity is increased by irradiating the surface of the uncured resin of the substrate with UV in advance and decomposing and removing organic molecules on the surface. Intrusion into the gap is likely to occur.

  In the above embodiment, the first substrate 1 is provided with the sample supply hole 4A and the sample discharge hole 4B communicating with the inner space recess 2. However, depending on the measurement mode, such as when the sample is contained in the inner space 5, There may be no need to provide a discharge hole. Moreover, in the said embodiment, although the sensor circuit 12 installed in the internal space 5 is one, and the resin supply hole 3 showed one example per one metal wiring 13, these installation numbers are arbitrary. For example, a plurality of resin supply holes 3 (two in the illustrated example) may be provided as shown in FIG. 4, and a plurality of sensor circuits 12 (three in the illustrated example) are provided as shown in FIG. May be.

Next, a composite substrate according to a second embodiment of the present invention will be described with reference to FIGS. In addition, the same member as 1st Embodiment attaches | subjects the same code | symbol, and abbreviate | omits the description.
In the composite substrate of the second embodiment, the first substrate 1 is formed with a wiring recess 7 that accommodates the metal wiring 13 formed on the second substrate 11 together with the sensor circuit 12. By accommodating the metal wiring 13 in the wiring recess 7, the first substrate 1 is not deformed or stressed due to sandwiching the metal wiring 13, and has a relatively wide lateral width and an undefined gap. 6 can be prevented. For this reason, the supply and penetration of the uncured resin from the resin supply hole 3 are limited to the wiring recess 13, and efficient sealing is possible.

  The wiring recess 7 may be sized and shaped so that the metal wiring 13 can be accommodated. However, considering the ease of manufacture, for example, when the metal wiring 13 is formed with a width of about 200 μm and a thickness of about 20 nm, the width of 260 to 260 is used. The depth may be about 300 μm and the depth is about 50 to 600 nm. However, these sizes are preferably determined so that the uncured resin can permeate appropriately. In this case, the wettability between the uncured resin liquid and the permeation surface, the viscosity and surface tension of the uncured resin liquid are taken into consideration. .

  The wiring recess 13 is processed by etching a portion corresponding to the pattern of the metal wiring 13 on the bonding surface of the first substrate 1. Thereafter, the resin supply hole 3 is processed, and a bonding process using hydrofluoric acid or the like is performed, so that the metal wiring 13 formed on the second substrate 1 is accommodated in the wiring recess 7 so that the second substrate 11 has the first substrate 1. Are overlapped and joined directly, and thereafter, an uncured resin is supplied from the resin supply hole 3, and penetrated and filled into the wiring recess 7 in which the metal wiring 13 is accommodated, and subjected to a curing process, whereby the wiring recess 7 is formed. The communication path formed by the wiring recess filled with the cured resin and connecting the internal space 5 and the outside is blocked, and the internal space 5 is sealed.

  When filling the wiring recess 7 with the cured resin R, as in the first embodiment, the wiring recess 7 penetrates and fills the open end of the wiring recess 7 that opens into the internal space 5, It is preferable to cure this. Also in this embodiment, at the opening end of the wiring recess 7, the inner peripheral surface of the wiring recess 7 and the inner peripheral surface of the inner space recess 2 are bent. The cured resin R can be easily filled up to the opening end of the wiring recess 7 by being cured in this state, and the inner surface of the inner space recess 2 can be made flush.

  Furthermore, in order to reliably stop the uncured resin at the opening end of the wiring recess 7, as shown in FIG. 9, before the first substrate 1 and the second substrate 11 are directly bonded, The wettability reducing film 9 that increases the contact angle between the uncured resin and the inner surface of the wiring recess 7 may be formed on the inner peripheral surface near the opening end where the wiring recess 7 opens to the inner surface of the inner space recess 2. For example, when the wiring recess 7 is sealed with a hydrophilic ultraviolet curable resin as an uncured resin, a carbon film having water repellency may be formed as the wettability reducing film 9. This carbon film is formed by depositing an amorphous carbon film having a thickness of about 100 to 300 nm on the bonding side surface of the first substrate 1 including the wiring recess 7 by CVD or the like, and then masking the inner peripheral surface near the opening end. Then, UV irradiation is performed. Thereby, the carbon film can be formed only on the inner peripheral surface in the vicinity of the opening end of the wiring recess 7 by decomposing and removing the amorphous carbon other than the region covered with the mask and removing the mask.

  In the second embodiment and the first embodiment, when an ultraviolet curable resin or silicon oil is used as the uncured resin, the gap 6 or the wiring recess 7 is applied in a state where a mask is applied in advance to a region that shields the internal space 5. The uncured resin is permeated and filled and irradiated with curing light (ultraviolet light) to suppress the curing of the uncured resin in the internal space 5 and to selectively select only the uncured resin present in the gap 6 and the wiring recess 7. Then, by removing the uncured resin in the internal space 5, it is possible to prevent unevenness from occurring in the internal space openings of the gap 6 and the wiring recess 7.

In the second embodiment, the wiring recess 7 is formed by etching the bonding surface of the first substrate 1. However, as shown in FIG. 10A, the pattern outside the pattern corresponding to the metal wiring 13 of the first substrate 1 is formed. By forming the SiO ₂ film 21 on the surface portion, the wiring recess 7 can be easily formed. Further, as shown in FIG. 10B, by forming a SiO ₂ film 22 on the surface portion outside the metal wiring pattern on the bonding surface of the second substrate 11 by, for example, CVD, a wiring recess is formed so as to include the metal wiring. 7 can be formed.
Also in the second embodiment, it is not necessary to provide the sample supply port 4A and the sample discharge port 4B depending on the application, and a plurality of sensor circuits 12 and resin supply holes 3 (two in the illustrated example) can be provided. .

It is a partially cutaway plan view of the composite substrate according to the first embodiment. It is A sectional view taken on the line A of FIG. FIG. 2 is a sectional view taken along line B in FIG. 1. It is a longitudinal cross-sectional view along the metal wiring of the composite substrate provided with the some resin supply hole. It is a partially cutaway top view of a composite substrate provided with a plurality of sensor circuits. It is a partially notched top view of the composite substrate which concerns on 2nd Embodiment. FIG. 7 is a sectional view taken along line A in FIG. 6. FIG. 7 is a sectional view taken along line B of FIG. It is a longitudinal cross-sectional view along the wiring recessed part of the 1st board | substrate with which the wettability reduction film was formed in the internal peripheral surface of the opening edge vicinity of a wiring recessed part. It is principal part sectional drawing of the board | substrate with which the wiring recessed part was formed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st board | substrate 2 Inner space recessed part 3 Resin supply hole 5 Inner space 6 Crevice 7 Wiring recessed part 9 Wettability reduction film 11 2nd board | substrate 12 Sensor circuit 13 Metal wiring 14 External electrode

Claims (6)

A first substrate having a concave portion for internal space microfabricated on the surface; and a second substrate directly bonded to the surface of the first substrate so as to seal the concave portion for internal space and form an internal space. And
On the surface of the second substrate, a metal circuit for electrically connecting the sensor circuit disposed in the internal space and the sensor circuit and an external electrode disposed outside is laminated,
A composite substrate in which the metal wiring is sandwiched between bonding surfaces of the first substrate and the second substrate, and a gap at a width direction end of the metal wiring generated thereby is sealed with a cured resin.   2. The composite substrate according to claim 1, wherein the first substrate is provided with a resin supply hole for supplying the uncured resin before curing of the cured resin through the gap. A first substrate having a concave portion for internal space microfabricated on the surface; and a second substrate directly bonded to the surface of the first substrate so as to seal the concave portion for internal space and form an internal space. And
On the surface of the second substrate, a metal circuit for electrically connecting the sensor circuit disposed in the internal space and the sensor circuit and an external electrode disposed outside is laminated,
A composite substrate, wherein the first substrate or the second substrate is formed with a wiring concave portion that accommodates the metal wiring, and the wiring concave portion that accommodates the metal wiring is sealed with a cured resin.   The composite substrate according to claim 3, wherein the first substrate is provided with a resin supply hole that supplies uncured resin before curing of the cured resin to the wiring recess.   5. The composite substrate according to claim 3, wherein an inner peripheral surface of the wiring recess and an inner peripheral surface of the inner space recess are bent at an opening end of the wiring recess in which the wiring recess opens into the inner space. . A wettability-reducing film that increases the contact angle between the uncured resin before curing of the cured resin and the inner surface of the wiring recess is formed on the inner peripheral surface near the opening end of the wiring recess where the wiring recess opens into the internal space. The composite substrate according to any one of claims 3 to 5.

Images