JPH0613426A - Assembly of hybrid semiconductor device having sensor part - Google Patents

Abstract

PURPOSE: To reduce assembly cost and to improve reliability by eliminating a process with a mechanical means by directly mounting a sensor to a semiconductor chip. CONSTITUTION: A sensor die 11 and an integrated circuit die 10 are manufactured separately, and then the sensor 11 is mounted to the semiconductor chip 10 by a solder protrusion 12. An insulator seal material 21 prevents the infiltration of a sealing material, such as a package into the sensor 11 by sealing the peripheral edge part of the sensor 11.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates generally to semiconductor device assembly, and more particularly to mounting at least one sensor die to an integrated circuit using solder bumps.

[0002]

Bulk micromachining (Bulk Micromachining) is the most commonly used method of manufacturing sensors today.
icro-machining) method. This bulk micromachining process is very costly and also adds extra cost when incorporating the manufactured sensor into other electronic components. Bulk micromachined sensors are typically encapsulated and sealed in expensive ceramic packages. The use of surface micromachining for sensor fabrication is a very cost effective method.

[0003]

Generally, a solid-state element sensor manufactured by micromachining and a semiconductor element related thereto are manufactured as two separate parts, and then connected through a circuit board, a wire and the like. This method requires a lot of space and is relatively expensive to assemble. Therefore, a method of realizing a direct sensor-to-integrated circuit bond that can reduce placement space, reduce defects in the assembly process, and improve reliability and consequently cost is highly desirable. There is.

[0004]

The objects and features of the present invention are realized by forming a hybrid circuit assembly comprising a sensor and an integrated circuit coupled by at least one solder bump. The sensor mounted on the integrated circuit is encapsulated by an insulating material that covers the peripheral edge of the sensor. This insulating material protects the sensor from various surrounding environments. The hybrid circuit assembly is then encapsulated with an encapsulant material.

In the preferred embodiment herein, the sensor is an accelerometer having at least one moving part.

[0006]

1 is a cross-sectional view of a hybrid circuit assembly. The hybrid circuit assembly includes an integrated circuit board 10 which is greatly simplified for purposes of illustration. Here, the integrated circuit board 10 may be an active device or a passive device, and a combination thereof, and these devices may operate independently or cooperate with a sensor device or a sensor die. It will be understood that it is okay. The sensor die 11 is shown in a raised position above the integrated circuit 10 to facilitate the design of the present invention. In this figure, a plurality of bonding sites or contact pads 16 are shown on integrated circuit 10 that are joined to sensor die 11 by solder bumps 12. The elevated sensor die 11 is shown here with a set of dashed lines 13 showing the mutual alignment of the sensor die 11, the solder bumps 12 and the integrated circuit 10. It will be appreciated that aligning the sensor die 11 with the integrated circuit 10 is an important step. If this step is not performed correctly, the signal transmission between the sensor 11 and the integrated circuit 10 will not work properly.

The hybrid circuit assembly is encapsulated by plastic material 14. Plastic material 14
Is cut away to better illustrate the interconnection between integrated circuit 10 and sensor 11. Integrated circuit 1
The plastic material used to seal the 0 may be selected from many materials represented by thermosetting liquid polyesters and the like. Integrated circuit 1 for simplicity
The connections from 0 to other circuits are not shown, but it will be understood that they are not necessary for an understanding of the invention. It will also be appreciated that the integrated circuit board 10 and the sensor 11 can be any type of circuit and sensor as is known in the art. For example, the sensor 11 may be an accelerometer, a pressure gauge,
A flow meter or the like may be used.

FIG. 2 is an enlarged sectional view showing the integrated circuit 10 and the sensor 11. Sensor 11 for illustration
Is shown as an accelerometer. It will be appreciated that not only can different types of accelerometers be used by those skilled in the art, but different types of sensors can be used as well. For reference, an accelerometer 11 having a cantilever is disclosed in US Pat.
Patented to John Cole on April 12, 1988 as 6,629. This accelerometer is incorporated here for reference.

Accelerometer 11 is turned upside down and aligned so that solder bumps 12 on sensor 11 electrically connect to contact pads 16 on the substrate of integrated circuit 10. Here, even if the solder protrusion 12 is on the sensor 11,
It may be either on the integrated circuit 10. Contact point 1
It is possible to thicken the metal part of 6 and / or the contact 18 to replace the solder bump 12, thereby providing a direct metallurgical bond to the metal parts 16 and 18. Become. Sensor die 11
The edges of the recess determine the perimeter of the recess 15, while the height of the recess 15 depends on the height of the solder bump 12, the contact pad 1 on the integrated circuit 10.
6 and the contact pad 18 on the sensor die 11. It will be appreciated that the capacitor plate 20 is now electrically continuous with the contact pad 18.
It will be appreciated that the design feature allows the contact pad 18 to be installed in this manner. The recess 15 contains a sensor capacitor, a cantilever beam 17, and the like. The space provided by the recess 15 is important for the illustrated accelerometer. This allows the cantilever beam 17 to move freely in response to acceleration. The use of weights 19 to assist movement of cantilever 17 in response to acceleration is well known in the art. It will be further appreciated that the weight 19 can be formed from many different materials. An example is US Pat. No. 4,736,62.
9, which is described in more detail in the preferred embodiment, polysilicon is used as the weight 19 in the preferred embodiment. The substrate of the sensor or the accelerometer 11, like the substrate of the integrated circuit 10, acts as a mechanical stop for the cantilever beam 17. This function prevents the cantilever beam 17 from excessively moving in response to severe acceleration and consequently damaging the cantilever beam 17. This feature thus allows the sensor device 11 to be used repeatedly, even after being exposed to accelerations beyond its design limits.

The insulating seal material 21 is used to protect precision parts such as an accelerometer from the outside world. Here, foreign matter is prevented from entering the inside and impeding the free movement of the cantilever beam 17. The sealing material 21 is the recess 1
It effectively separates the precision components within 5 from contaminants in the environment and, more importantly, prevents the encapsulating material of the package from entering recess 15. The sealing material 21 can be used from many different insulating materials such as semi-molten glass, epoxy and the like. The semi-molten glass is added in paste form and then melted by heat to form a seal.

It will be apparent that an improved means has now been provided for joining a semiconductor circuit and a sensor device.
Hybrid circuit assembly allows the sensor and integrated circuit to be directly bonded and encapsulated in a low cost plastic package. This eliminates many steps that were required in the past, resulting in improved reliability and lower cost of the assembly process. Yet another advantage of using the present invention is that it provides the possibility to use the process by common electrical means for many different types of sensors. The use of processes by common electrical means also leads to cost savings.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention in a partially exploded simplified exploded view.

FIG. 2 is an enlarged sectional view showing a part of the embodiment shown in FIG.

[Explanation of symbols]

 10 Semiconductor Device 11 Sensor (Sensor Die) 12 Solder Protrusion 15 Recess (Working Space) 16 Contact Protrusion 21 Sealing Material

Claims (3)

[Claims] 1. A hybrid circuit assembly comprising: a sensor (11); and a semiconductor integrated circuit (10); the sensor (11) and the semiconductor integrated circuit (10).
Is electrically coupled to each other by solder lugs (12), a hybrid circuit assembly. 2. The sensor die (11) is integrated circuit device (1).
0) to the sensor die (1)
1) preparing; aligning the sensor die (11) with the integrated circuit device (10), and contacting the sensor die (11) with the integrated circuit device (10) by solder protrusions (12) And sealing the peripheral edge of the sensor die (11) to protect the working space (15) of the sensor die (11) from the ambient environment. 3. The method of claim 2, wherein the step of sealing the peripheral edge of the sensor die (11) comprises adding semi-molten glass to the peripheral edge of the sensor die (11) and then applying the glass. A method characterized by being carried out by heating.