阅读说明：本技术 应力敏感集成电路管芯的附接 (Attachment of stress sensitive integrated circuit die ) 是由 卡斯·范德阿福尔特 威廉·弗雷德里克·阿德里亚努斯·贝斯林 瑞曼科·亨里克斯·威廉姆斯·皮内伯格 于 2018-11-16 设计创作，主要内容包括：一种半导体封装,包括：通过管芯的背面上的粘合剂附接到支撑件的管芯。粘合剂仅覆盖管芯的背面的一部分,并且能够在管芯的背面上形成为条形或其他不连续的区域。(A semiconductor package, comprising: the die is attached to the support by an adhesive on the back side of the die. The adhesive covers only a portion of the back side of the die and can be formed as stripes or other discrete areas on the back side of the die.)

1. A semiconductor package, comprising:

a support member; and

a die attached to a support by an adhesive on a backside of the die, wherein the die comprises a capacitive pressure sensor integrated on a CMOS readout circuit, wherein the adhesive covers only a portion of the backside of the die.

2. The package of claim 1, wherein the adhesive has a plurality of discrete areas on the back side of the die.

3. The package of claim 2, wherein the adhesive has two discontinuous stripe-shaped areas on the back side of the die.

4. The package of claim 3, wherein the strip-shaped region of adhesive is disposed adjacent an edge of the die.

5. The package of claim 3, wherein the capacitive pressure sensor comprises a rectangular suspended tensile membrane, and wherein the strip-shaped regions of adhesive are oriented parallel to the longer sides of the membrane.

6. The package height of claim 1, wherein the maximum thickness of the die is no greater than 250 um.

7. The package of claim 6, wherein the maximum height of the package is no greater than 0.8 mm.

8. The package of claim 1, comprising air channels in the adhesive to allow for outward diffusion of water vapor.

9. The package of claim 2, wherein the adhesive includes a plurality of discrete regions on the backside of the die at corner points thereof.

10. The package of any of claims 1-9, wherein the support comprises a die pad, wherein the die is attached to the die pad by an adhesive.

11. A semiconductor package, comprising:

a support member; and

a die attached to the support by an adhesive on the back side of the die, wherein the adhesive covers only a portion of the back side of the die, wherein the adhesive has a plurality of discontinuous stripe-shaped areas on the back side of the die.

12. The package of claim 11, wherein the strip-shaped region of adhesive is disposed adjacent an edge of the die.

13. The package of claim 12, wherein the die comprises a capacitive pressure sensor having a rectangular suspended tensile membrane, and wherein the strip-shaped regions of adhesive are oriented parallel to the longer sides of the membrane.

14. A semiconductor package, comprising:

a support member; and

a stack of two or more semiconductor dies, wherein the stack comprises an upper die and further comprises a lower die attached to a support by an adhesive on a back side of the lower die, wherein the adhesive covers only a portion of the back side of the lower die, and wherein the adhesive has a plurality of discrete areas on the back side of the lower die.

15. The package of claim 14, wherein the upper die comprises a capacitive pressure sensor, and wherein the lower die comprises CMOS readout circuitry.

16. A semiconductor package, comprising:

a support member; and

a stack of two or more semiconductor dies, the stack comprising a lower die attached to a support, and further comprising an upper die attached to the lower die by an adhesive on a back side of the upper die, wherein the adhesive covers only a portion of the back side of the upper die, and wherein the adhesive has a plurality of discrete areas on the back side of the upper die.

17. The package of claim 16, wherein the upper die comprises a capacitive pressure sensor, and wherein the lower die comprises CMOS readout circuitry.

Technical Field

The present disclosure relates to the attachment of an integrated circuit die to a carrier.

Background

Pressure sensors, such as micro-electromechanical system (MEMS) sensors, have many applications. These sensors can be used in, for example, automotive, consumer, industrial, medical, and other applications. In a MEMS sensor, for example, pressure can be measured by deflection of a membrane caused by external pressure. However, large deflections or temperature differences can cause significant non-linearities in the sensor, which can present challenges in various applications. The precise and repeatable manufacturing process of the membrane and pressure sensor can allow for more accurate pressure readings over a range of temperatures and pressures.

Although some thermal effects and associated stresses are predictable and can therefore be included in the calibration device, the overall stress state of the sensor die may be altered by other influences, such as bending of the carrier on which the sensor is mounted and/or moisture absorption that causes uneven expansion of the carrier. For ultra-sensitive pressure sensors, such changes often result in undesirable sensor output drift.

Disclosure of Invention

The present disclosure describes packages that can accommodate, for example, stress sensitive dies that need to be packaged in low-profile packages for the wearable/consumer/mobile market and that can benefit from stress decoupling without increasing the stack height. Typically, the package includes a semiconductor die attached to a support by an adhesive on the back side of the die. The adhesive covers only a portion of the back side of the die and can be formed on the back side of the die as, for example, stripes or other discrete areas.

For example, in one aspect, the present disclosure describes a semiconductor package that includes a support and a die attached to the support by an adhesive on a backside of the die. The die includes a capacitive pressure sensor integrated on a CMOS readout circuit. The adhesive covers only a portion of the backside of the die.

Some implementations include one or more of the following features. For example, the adhesive can have a plurality of discrete areas on the back side of the die. In some cases, the adhesive has two discontinuous stripe-shaped areas on the back side of the die. The stripe-shaped areas of adhesive can be disposed adjacent to, for example, the edges of the die. In some cases, for example, where the capacitive pressure sensor comprises a rectangular suspended tensile membrane, the stripe-shaped areas of adhesive can be oriented parallel to the longer sides of the membrane.

The present disclosure can be particularly advantageous for embodiments where the maximum thickness of the die is no greater than 250um and/or the overall height of the packaged product is no greater than 0.8 mm.

In another aspect, the present disclosure describes a semiconductor package that includes a support and a die attached to the support by an adhesive on a backside of the die. The adhesive covers only a portion of the back side of the die and has a plurality of discrete (e.g., stripe-shaped) areas on the back side of the die.

In yet another aspect, the present disclosure describes a semiconductor package that includes a stack of two or more semiconductor dies and a support. The stack includes an upper die and a lower die. In some cases, the lower die is attached to the support by an adhesive on the back side of the lower die such that the adhesive covers only a portion of the back side of the lower die and has a plurality of discrete areas on the back side of the lower die. In some cases, the upper die is attached to the lower die by an adhesive on the back side of the upper die such that the adhesive covers only a portion of the back side of the upper die, and wherein the adhesive has a plurality of discrete regions on the back side of the upper die.

Some embodiments include one or more of the following advantages. In some cases, the patterned adhesive improves packaging compared to using a solid adhesive layer. For example, the adhesive can act as a rolling bearing to prevent bending moments from being transmitted to the pressure sensor.

Other aspects, features, and advantages will be apparent from the following detailed description, the accompanying drawings, and the claims.

Drawings

Fig. 1 shows an example of a package housing a semiconductor die.

Fig. 2 shows an example of a die including a capacitive pressure sensor.

Fig. 3A shows a first example of an adhesive pattern. Fig. 3B is a top view of the arrangement of fig. 3A.

Fig. 3C shows a second example of an adhesive pattern. Fig. 3D is a top view of the arrangement of fig. 3C.

Fig. 4A and 4B show examples of stacks of dies. Fig. 4B is a top view of the arrangement of fig. 4A.

Fig. 5A and 5B show examples of stacks of dies. Fig. 5B is a top view of the arrangement of fig. 5A.

FIG. 5C is a top view of the alternative embodiment of FIG. 5A, wherein the membrane of the capacitive sensor is square.

Fig. 6 shows an example of a microphone/pressure sensor combination package.

Detailed Description

As shown in fig. 1, device package 10 includes a die (e.g., semiconductor chip) 12. In the example shown, the die 12 includes an Application Specific Integrated Circuit (ASIC) with an integrated capacitive pressure (e.g., MEMS) sensor. The package 10 includes a support 14 to which the die 12 is attached. The support 14 can be implemented, for example, as a single or multi-layer (e.g., laminated) substrate, the surface of which facing the interior of the package 10 can include die pads 16 and one or more adhesive pads 18 for electrical connections 20 to and from the integrated circuit die 12. The die 12 is attached to the support (e.g., die pad) 16 by an adhesive 22 (e.g., glue) that is present on only a portion of the back side of the die 12. Thus, in areas of the backside of the die where there is no adhesive, there is a small gap between the upper surface of the die pad 16 and the backside of the die 12.

The package 10 also includes one or more pads 24 on its outer lower surface. The package 10 also includes a metal or other cap 26 that shields the die 12. The cover 26 can have a small opening 28 that provides access to ambient pressure. In some embodiments, the cover 26 is fully closed, but the support 14 has a port to provide access to ambient pressure.

In some embodiments, the package 10 is relatively thin (e.g., ≦ 0.8mm) and includes a single die 12 having a thickness of no greater than 250 um. In some cases, the height of the package is less than 0.7 mm.

Fig. 2 shows various details of an example of a capacitive pressure sensor that can be integrated into the die 12. As shown in fig. 2, the semiconductor device 100 includes a capacitive pressure sensor 108 formed over the integrated circuit 106. Capacitive pressure sensor 108 includes a suspended tensioned membrane 102 over a cavity 112. The sensor 108 also includes a bottom electrode 104, which in some embodiments is formed on top of the final passivation layer of the CMOS readout circuitry. The electrodes and the suspended membrane of the capacitive pressure sensor 108 can be electrically connected to the integrated circuit 106. The bottom electrode 104 may be segmented and may include a plurality of annular rings. The two or more anchor slots 114 laterally surrounding the cavity 112 are filled with a first conductive material and are separated from each other by an oxide support layer (e.g., silicon oxide) 126.

The first conductive material filling the anchor trench 114 can include, for example, PVD Ti/TiN liner and CVD tungsten (W). The sidewalls of the cavity 112 are at least partially formed from the conductive material of the internal anchor slots 114A. The suspended membrane 102 can be composed of a second conductive material, e.g., tungsten (W), and extends beyond the outer anchor groove 114B. Thus, the first conductive material 114 serves as a support anchor for the suspended membrane 102. The first conductive material 114 and the film 102 form a portion of the top electrode that floats above the bottom electrode 104. The cavity 112 separates the membrane 102 and the bottom electrode 104 from each other. The isolation trench 130 can separate the bottom electrode from the connection 120 for the top electrode. The semiconductor device 100 also depicts a conductive connection 120 connecting the top electrode or membrane 102 to the integrated circuit 106 or elsewhere. The semiconductor device 100 may also include aluminum or other contact pads to provide a connection to another device. Various vias may extend from the contact pad down to the bottom electrode and also down from the bottom electrode to the CMOS top metal layer.

The foregoing details shown and described in connection with fig. 2 are merely examples of the types of die 12 that can be attached to the die pad 16 in the package 10 by the adhesive 22. Thus, the various inventive concepts described in this disclosure can also be used with other integrated circuit dies.

As described above, the die 12 is attached to the die pad 16 by the adhesive 22 that is present on only a portion of the back side of the die 12. This can be accomplished, for example, by depositing adhesive 22 in a pattern on selected areas of the backside of die 12. In some embodiments, the adhesive 22 is disposed in dots on multiple (e.g., two, three, four, or more) areas of the backside of the die 12. For example, as shown in fig. 3A and 3B, small amounts of adhesive 202 are disposed on the backside of the die 12 at its four corner points 204. In some cases, the adhesive dots 202 have a diameter of about 300 μm, 200 μm, or less. Other areas of the backside of the die are not covered by the adhesive. The deposition of adhesive at the corner points 204 of the die 12 results in the die 12 being suspended at the corner points and can reduce the transfer of bending moments to the suspended die 12 in both directions. In the example of fig. 3A-3B, the integrated pressure sensor includes two membranes 102A, 102B. For other embodiments, the number of membranes may be different.

In some embodiments, as shown in fig. 3C and 3D, the adhesive is disposed on the back side of the die 12 in a plurality of stripes 206. The adhesive strip 204 can be disposed adjacent to, for example, an edge 208 of the die 12. In some cases, such as for a rectangular pressure sensor membrane 102, the strip 204 of adhesive is in a particular orientation relative to the orientation of the membrane 102 on the die 12. For example, in the example shown, where the pressure sensor includes two membranes 102A, 102B, the adhesive strip 204 is oriented parallel to the longer side of the rectangular membrane. Such a pattern of adhesive can help reduce bending moments in at least one direction (e.g., a direction perpendicular to the adhesive stripes 204). Since rectangular films are generally more sensitive to stress in a direction parallel to the respective shorter sides of the film, providing an adhesive on the back side of the die 12 in a direction parallel to the longer sides of the film can help reduce stress. In some embodiments, the number of adhesive stripes may vary. Also, adhesive strips can be used when the pressure sensor comprises a different number of membranes.

Various adhesives may be used. In some cases, a flexible adhesive with a shore durometer hardness rating (shore a) of less than 50 is used. In some cases, it is desirable to use a low stiffness silicon-based adhesive (e.g., available from Wacker Chemie AG)988/1k adhesive). In some cases, silicon glues with low young's modulus and B-class glues can be used. Some of the adhesives are thermally cured, and in some cases, cured at elevated temperatures (e.g., in the temperature range of 100 ℃ to 200 ℃) rather than at room temperature. In some cases, the adhesive can be or include Polydimethylsiloxane (PDMS). For some embodiments, the adhesive can be based on acrylate chemistry or polyurethane derivatives. Polyurethane derivatives can be advantageous because partial curing can be accomplished by exposure to Ultraviolet (UV) radiation, followed by die placement and final thermal curing. Thus, the shape of the adhesive deposit can be more easily maintained (i.e., not adversely affected by flow during die placement and curing). Such adhesives may be available from, for example, the DELO industry of Germany (e.g., DELO)AD 345).

In some embodiments, the adhesive can be easily dispensed using any of a wide range of dispensing devices. The adhesive can be dispensed, for example, from a nozzle. For example, adhesive can be applied, for example, by an edge of the top of the support 14 or a groove in the support to provide mechanical restraint. For some embodiments (e.g., very small die), the adhesive should be selected so that it can be dispensed as small drops of glue with sufficient support height. If the thixotropy (i.e., shear thinning effect) of the adhesive is too low, the adhesive may flow too easily, destroying its desired shape. In some cases, the silicone adhesive can be applied at least twice to increase the adhesive height and avoid adhesive run-off.

By dividing the adhesive layer into separate regions, various advantages can be obtained in some embodiments. In some cases, the adhesive layer reduces the ability of deformation to be transferred from the substrate 14 to the die 12. Also, air channels can be provided in the adhesive to allow rapid ingress and egress diffusion of water vapor. The contact area of adhesive 22 and substrate 14 with the environment is effectively increased, thereby reducing the number of diffusions of oxygen, water vapor, or other gases that may act on the polymer of adhesive 22 and/or substrate 14. A reduction in these times may reduce the delay in the response of the temperature dependent sensor.

The use of patterned adhesive 22 can result in the elimination or significant reduction of bending moments resulting from mechanical deformation or hygroscopic expansion in the packaged sensor. Furthermore, the foregoing techniques can be particularly advantageous for thin packages (i.e., ≦ 0.8mm) that include a single die having a thickness of no greater than 250 um. In particular, the techniques described herein can improve stress decoupling without increasing the overall stack height of the package 10.

In some cases, the techniques described herein can provide a low-cost solution that improves the accuracy of pressure sensors. This technique enables accurate use of the sensor in environments with non-constant relative humidity of the ambient air. These features can enhance the use of the sensor in applications related to indoor navigation, such as applications entering an air-conditioned shopping mall from a wet outside. Even in such an environment, the barometric pressure altitude calculated by the pressure sensor should remain stable.

Furthermore, the techniques described herein can enable high accuracy to be maintained even under conditions where temperature is not constant. It is well known that different temperatures may result in different levels of board level stress and package level stress due to differences in the Coefficients of Thermal Expansion (CTE). The enhanced level of stress decoupling using patterned adhesives can eliminate or reduce these stresses.

While the techniques described herein can be particularly advantageous for packages that house a single die 12 that includes an ASIC with integrated capacitive pressure sensors, the techniques can also be used in solutions where the package houses two or more semiconductor dies stacked one on top of another (e.g., sensors resulting from stacking on a CMOS readout circuit die). In some cases, as shown in fig. 4A and 4B, an adhesive applied to the back side of the lower die is used to attach the lower die (e.g., CMOS readout circuit die) 12B to a die pad, such as support 14, such that the adhesive covers only a portion of the back side of the lower die 12B (e.g., using adhesive dots 202 at the corner points of the underside of the die as shown in fig. 4A-4B, or using adhesive strips). An upper die (e.g., a die including stress sensitive sensors or transducers) 12A can be attached to a lower die 12B, for example, by standard die attach foil 30. Electrical connections 20A can be disposed between upper die 12A and lower die 12B, for example, using adhesive lines.

In some cases, as shown in fig. 5A and 5B, a lower or bottom die (e.g., a CMOS readout circuit die) 12B is attached to the die pads of the support 14 using standard die attach foil 30. However, the upper die or top die (e.g., die including stress sensitive sensors or transducers) 12A can be attached to the bottom die 12B using the adhesive 22 applied to the backside of the top die 12A such that the adhesive covers only a portion of the backside of the upper die 12A (e.g., using adhesive dots s02 at the corner points of the underside of the die as shown in fig. 5-4B, or using adhesive strips). Although the illustrated example of fig. 5B shows a rectangular membrane 102 having shorter and longer sides, in some cases, the membrane 102 can be square as shown in fig. 5C. Further, some embodiments may include more than one membrane.

The arrangement of fig. 5A-5B can be used, for example, in a microphone/pressure sensor combination package, where the bottom die 12B is an ASIC (e.g., CMOS readout circuitry) for the microphone and the top die 12A is an ASIC that includes an integrated pressure sensor that includes one or more membranes 102A, 102B. Fig. 6 shows an embodiment that includes electrical connections 20, 20A from the integrated pressure sensor die 12A and the CMOS readout circuitry die 12B to respective adhesive pads 18 on the support 14, and that also includes electrical connections 20B from the CMOS readout circuitry die 12B to the microphone die 12C.

Each of the foregoing embodiments discussed in connection with fig. 3A-3D, 4A-4B, 5A-5C, and 6 can form a portion of a package that houses a die such as that shown in fig. 1.

Other implementations are within the scope of the following claims.