Source: https://insight.rpxcorp.com/pat/US7296471B2
Timestamp: 2019-06-18 02:36:26
Document Index: 12463967

Matched Legal Cases: ['arts 11', 'arts 10', 'arts 11', 'arts 11', 'arts 11', 'arts 11', 'arts 20', 'arts 11']

Patent US 7,296,471 B2
a stopper substrate with a window portion through which, in order to guide an output signal of the detection element via a pad that is formed on the upper end face of the support portion, a conductor lead that connects the pad connects to a terminal outside the stopper substrate, wherein the stopper substrate is fixed by means of adhesive to a region on the upper end face of the support portion, surrounding the pad formed on the upper end face of the support portion and upward overswing of the weight is limited by means of the stopper substrate.
Semiconductor acceleration sensor and fabrication method thereof
US 20070144259A1
US 5,520,051 A
A variety of devices for detecting this stress or acceleration have been conventionally developed, of which one device is known in which a gauge resistor is formed on the semiconductor substrate as a detection element and which converts the mechanical strain produced on the basis of a force acting on the that is supplied from outside into an electrical signal as a result of the piezoresistive effect ("Development of three-weight sensor" `Invention` Journal pages 52 to 63, published by the Invention Society on September 2003).
In addition, the fact that it is also possible to use a change in the electrostatic capacity corresponding with strain instead of using the piezoresistive effect of the gauge resistor is explained in "Development of three-weight sensor" `Invention` Journal pages 52 to 63, published by the Invention Society on September 2003.
In particular, the characteristic of the invention that is described in "Development of three-weight sensor" `Invention` Journal pages 52 to 63, published by the Invention Society on September 2003 is the fact that it is possible, by means of force sensors for a plurality of axial directions formed on a semiconductor substrate, to constitute sensors of a plurality of types, that is, sensors of four types, namely, a three-axis force sensor, a three-axis acceleration sensor, a three-axis angular speed sensor, and a six-axis motion sensor by means of one device.
Proposals have been made for each of a variety of problems relating to a semiconductor acceleration sensor that employs the principles mentioned in "Development of three-weight sensor" `Invention` Journal pages 52 to 63, published by the Invention Society on September 2003. One of these various problems is that a large unforeseen shock can sometimes be applied as a result of the environment in which the acceleration sensor is applied (depending on what kind of device the acceleration sensor is used in). In such a case, there is a risk that the weight will be displaced greatly and the gauge resistor will be accordingly damaged.
Here, as indicated in "Development of three-weight sensor" `Invention` Journal pages 52 to 63, published by the Invention Society on September 2003 and in Japanese Patent publication H8-7228, an acceleration sensor with a structure in which the relationship between the weight and support portion is reversed, that is, in which the support portion is placed in the center of the acceleration sensor and the weight is suspended by means of a beam portion at the periphery of the support portion, is known. In the following description, an acceleration sensor with this structure is expediently referred to as a parasol-type acceleration sensor.
An acceleration sensor with a parasol-type acceleration sensor structure in which this support portion is placed in the center is illustrated in "Development of three-weight sensor" `Invention` Journal pages 52 to 63, published by the Invention Society on September 2003, Japanese Patent Application Laid Open No. 2000-304762, and Japanese Patent publication H8-7228. However, the application of a structure that limits shocks of the acceleration sensor shown in Japanese Patent Application Laid Open No. 2000-304762 to a parasol-type acceleration sensor is not suggested.
The eighth aspect of the acceleration sensor according to the object of the present invention is an acceleration sensor according to the first to seventh aspects, wherein the interval between the weight and the stopper substrate is 2 to 12 .mu.m.
Here, the present invention is characterized by further comprising the upper stopper substrate 15 that fulfils the role of a stopper for the upward movement of the weight 11. The upper stopper substrate 15 is bonded by means of adhesive 15b formed to surround the plurality of bonding pads 14 to the upper end face of the support portion 10.
FIG. 2C is a planar view of the upper stopper substrate 15 that fulfils the role of a stopper to limit the overswing of the upward movement of the weight 11. The upper stopper substrate 15 comprises a window portion 15a at the center thereof. Therefore, the connecting wires 5 are able to connect the bonding pads 14 and external lead-out terminals 4 via the window portion 15a of the upper stopper substrate 15.
Here, so too with the third embodiment, the present invention is characterized by further comprising the stopper substrate 15 that fulfils the role of a stopper for the upward movement of the weight 11. In the second embodiment, the weight 11 forms a substantially square frame shape with four sides, the center of each of the four sides being connected to the other end of the beam portion (detection beam) 12 and linked to the middle support portion 10. In addition, in comparison with the first embodiment in FIG. 2, in the case of the third embodiment, the middle support portion 10 comprises extension parts 11a to 11d of the support portion that extend in an oblique direction at an angle to the beam portion (detection beam) 12.
Furthermore, a characteristic of this embodiment is that the upper stopper substrate 15 is bonded by means of adhesive 15b to extension parts 10a to 10d of the support portion 10. FIG. 3C is a planar view of the upper stopper substrate 15 that fulfils the role of a stopper to limit the overswing of the upward movement of the weight 11. Similarly to the first embodiment, the upper stopper substrate 15 comprises a window portion 15a at the center thereof. Therefore, the connecting wires 5 are able to connect the bonding pads 14 and external lead-out terminals 4 via the window portion 15a of the upper stopper substrate 15.
In comparison with the first embodiment, the second embodiment shown in FIG. 3 is a constitution in which the upper stopper substrate 15 is bonded at four points spaced apart from the plurality of bonding pads 14, whereby the bonding strength can be increased and the flow of adhesive 15b to the bonding pads 14 can be prevented. Deterioration of the electrical connection can therefore be prevented.
Here, so too with the fourth embodiment, similarly to the earlier embodiments, the present invention is characterized by comprising the stopper substrate 15 that fulfils the role of a stopper for the upward movement of the weight 11. Similarly to the second embodiment in FIG. 3, the weight 11 forms a substantially square frame shape with four sides, the center of each of the four sides being connected to the other end of the beam portion (detection beam) 12 and linked to the middle support portion 10. In addition, the middle support portion 10 comprises extension parts 11a to 11d of the support portion that extend in an oblique direction at an angle to the beam portion (detection beam) 12.
The difference of the fourth embodiment from the second embodiment shown in FIG. 3 is the position of the plurality of bonding pads 14. That is, in the embodiment shown in FIG. 4, the plurality of bonding pads 14 are arranged on four extension parts 11a to 11d of the extended support portion. Therefore, the upper stopper substrate 15 comprises four window portions 15a for connecting a lead-out wire such as the metal wire 5 to the bonding pads 14 in correspondence with the four extension parts 11a to 11d respectively.
Furthermore, the upper stopper substrate 15 is connected to the support portion 10 by means of adhesive 15b that is formed on the upper end of the support portion 10.
This embodiment is a constitution in which a frame 19 for holding the upper stopper substrate 15 is provided independently of the acceleration sensor chip 2. As shown in FIG. 5C, the upper stopper substrate 15 comprises a window portion 15a through which lead-out wire such as the metal wire 5 for connecting the bonding pads 14 and external lead-out terminals 4 is passed as per the other embodiments.
The window portion 15a forms a square in this embodiment but may also form another shape such as a circle, for example. In addition, in FIG. 5, the plurality of bonding pads 14 is formed on the end face of the support portion 10 similarly to the second and third embodiments. However, the bonding pads 14 may also be formed on each of the four extension parts 11a to 11d as per the fourth embodiment.
FIG. 6 illustrates the constitution of the fabrication process for the acceleration sensor chip 2 and frame 19 of the embodiment in FIG. 5. The acceleration sensor chip 2 and frame 19 can be fabricated by cutting same from a semiconductor substrate by means of micromachine technology. Thus, machining is performed by leaving parts 20a to 20d that link the parts of the frame 19 and acceleration sensor chip 2.
FIG. 7 is a modified example of the embodiment shown in FIG. 3. This modified example is characterized in that grooves 21 are formed between the adhesive 15b for fixing the upper stopper substrate 15 formed on the four extension parts 11a to 11d and the bonding pads 14. As a result of forming these grooves 21, the risk of adhesive 15b flowing to the part of the bonding pads 14 can be avoided. Accordingly, an acceleration sensor with superior shock resistance with which electrical connection reliability is high can be provided.
FIG. 8 illustrates a gap G between the weight 11 and upper stopper substrate 15 of an acceleration sensor common to each embodiment. It is possible to limit the upward movement of the weight 11 by making the gap G approximately 2 to 12 .mu.m by means of the adhesive 15b or by inserting a spacer. As a result, the reliability of the shock resistance can be improved.
Tanaka, Hiroshi, Ishikawa, Hiroshi, Yamada, Sumio
US 20060130584A1