JP2002246488A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a functional surface such as a sensor surface of a fingerprint sensor from mechanical damage, due to collision of outside foreign matters and damage due to static electricity. SOLUTION: A protection pins 105, which project freely in the periphery of a fingerprint recognition surface 101, are dispersed and energized in a projection direction by a coil spring 106. When it is not used, a fingerprint recognition surface is mechanically protected from an unexpected approaching finger or a foreign matter by the protection pin 105 projecting in the periphery of a fingerprint recognition surface. Furthermore, a finger print sensor can be protected from electrostatic discharge damage by discharging the static electricity charged on a body from a finger 109 through the pins 105. Moreover, it is constituted to operate a power supply switch 108 of a finger print sensor, in conjunction with the vertical movements of the pins 105. Thereby, it is possible to eliminate complicated switch operations, when a finger print recognizing semiconductor device is operated and to prevent a power supply from being carelessly turned 'on', when it is not used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a function of mechanically and electrically protecting a functional surface in various functional devices having a functional surface formed by exposing a part of a semiconductor element to the outside. For example, the present invention relates to a semiconductor device which is effective when applied to a fingerprint sensor.

[0002]

2. Description of the Related Art In recent years, fingerprint collation systems, which have often been used for entry / exit management, have recently attracted attention as security systems on a computer network and personal authentication roots in portable terminals and the like. As a fingerprint detection method using such a fingerprint collation system, for example, an electrostatic capacitance detection method as disclosed in Japanese Patent Application Laid-Open No. 4-281803 has been proposed. This capacitance detection method is a method of detecting a capacitance value (hereinafter simply referred to as a capacitance value) between an electrode of a fingerprint sensor and a finger. Since the capacitance type, in which the device is easily miniaturized, is advantageous as compared with the detection type, the development of the capacitance type fingerprint sensor has been actively promoted.

FIG. 6 is a cross-sectional view showing the structure of a fingerprint recognition semiconductor device constituting such a capacitance type fingerprint sensor, and FIG. 7 is an internal view of the fingerprint recognition semiconductor device shown in FIG. It is a fragmentary sectional view which expands and shows a structure. FIG. 8 is a circuit diagram showing a configuration of a detection signal extracting unit in the semiconductor device for fingerprint recognition shown in FIG. This semiconductor device has a semiconductor chip 51 for fingerprint recognition. This semiconductor chip 51 is formed on a semiconductor substrate 10 on which various semiconductor elements such as a transistor constituting a fingerprint sensor are formed on a barrier metal made of Ti or the like. 2
No. 0 is formed, a charge storage electrode 52 and a pad electrode 52a are provided thereon, and further packaged with an insulating protective film 53 such as a passivation film.

[0004] The charge storage electrodes 52 are made of, for example, aluminum or the like, are arranged in a matrix, and are connected to semiconductor elements in a substrate. A region where the charge storage electrodes 52 are arranged in a matrix is configured as a fingerprint recognition surface of the fingerprint sensor. The pad electrode 52a is formed in the same step as the charge storage electrode 52. The insulating protection film 53 is formed of the charge storage electrode 5.
2 and the upper surface of the pad electrode 52a, but an opening is formed in the upper surface portion of the pad electrode 52a.
The fingerprint recognition semiconductor chip 51 configured as described above is further fixed on a die pad (not shown) of a lead frame having leads 55, and is connected to the pad electrode 52a by wire bonding. In a state where the fingerprint recognition surface of the fingerprint recognition semiconductor chip 51 is exposed, a portion of the wire bonding 54 connecting the fingerprint recognition semiconductor chip 51 and the lead 55 is formed by a molding resin 56 made of, for example, a thermosetting resin. Seal.

Next, the operation of such a conventional semiconductor device for fingerprint recognition will be described. As shown in FIG. 7, when the finger 7 touches the fingerprint recognition surface of the fingerprint recognition semiconductor device, a capacitor is formed between the charge storage electrode 52, the insulating protective film 53, and the finger 7. Here, the insulating protective film 53 functions as a part of the capacitor insulating film. Then, the distance d (for example, d1, d2) between each charge storage electrode 52 and the finger 7 fluctuates according to the unevenness 70 of the fingerprint. Therefore, a difference occurs in the capacitance of the capacitors arranged in a matrix that constitute the fingerprint sensor, and the charges stored in each charge storage electrode 52 are read out and detected by a semiconductor element such as a transistor formed on the substrate 10. By doing so, it is possible to perform fingerprint recognition. Here, each charge storage electrode 5
2 constitutes a unit cell of the fingerprint recognition surface of the semiconductor device for fingerprint recognition. When the finger is not in contact with the fingerprint recognition surface, d is infinite in all the unit cells of the fingerprint recognition surface of the fingerprint recognition semiconductor device when the finger is not in contact with the fingerprint recognition surface. The capacitance value Cs = 0.

On the other hand, when the finger is in contact with the fingerprint recognition surface, as shown in FIG.
A capacitor having a capacitance value Csn is formed between the charge storage electrode 52, the insulating protective film 53, and the finger 7. The above-mentioned capacitance value Csn is represented by Csn = ε · ε0 · S / dn. Here, S is the area contributing to the capacitor of each electrode, dn is the distance between the electrode of the n-th unit cell and the finger (eg, d1, d2), and n is the number of each unit cell (n =
1, 2, ...). In the configuration for reading out the capacitance value Csn in each unit cell described above, a capacitor formed between the charge storage electrode 52, the insulating protective film 53, and the finger 7 in each unit cell may be, for example, a word line WL (WL
1, WL2,...) Are connected to the source / drain diffusion layers of the transistors whose gates are controlled, and the other source / drain diffusion layers are connected to the bit lines BL (BL1, BL
2,...), And a capacitor having a capacitance value CB is further connected to the bit line BL. In the above configuration, when a finger comes into contact with Vcc applied to the bit line BL (Vcc precharge), the potential change of the bit line BL represented by ΔVn = [Csn / (CB + Csn)] · Vcc is generated. Occurs. By detecting the potential change ΔVn in each cell, the capacitance value Csn of each unit cell is calculated, and the fingerprint is recognized by performing image processing or the like.

[0007]

However, in the above-described conventional semiconductor device for fingerprint recognition, unlike a general semiconductor device, the fingerprint recognition surface is used without being surrounded by a package or the like, so that foreign matter is not present on the fingerprint recognition surface. Colliding or rubbing on the fingerprint recognition surface
There has been a problem in that the reliability of the semiconductor device for fingerprint recognition is reduced, or the function itself as the semiconductor device for fingerprint recognition is lost when the degree is low. In addition, since the finger directly contacts the fingerprint recognition semiconductor device, static electricity charged on the human body is discharged to the charge storage electrode 52,
There is also a problem that a large current flows through the detection circuit (FIG. 8) formed on the same substrate through the charge storage electrode 52 to break the circuit and lose its function as a semiconductor device for fingerprint recognition. On the other hand, the protective film on the surface of the semiconductor device for fingerprint recognition functions as a part of the capacitor insulating film of the capacitor formed between the electrode, the insulating protective film, and the finger as described above, so that the external functional film is not provided. In order to prevent damage to the fingerprint recognition surface due to impact and damage to the circuit due to static electricity discharge, there is a problem that it is not possible to take measures such as increasing the thickness of the insulating protective film or changing the material. .

Accordingly, an object of the present invention has been made in view of the above problems, and an object of the present invention is to provide a semiconductor device capable of effectively protecting a functional surface of a semiconductor from mechanical damage and electrostatic damage due to external factors. Is to provide.

[0009]

According to the present invention, there is provided a semiconductor device having a functional surface in which a part of a semiconductor element is exposed to the outside. A holding member for holding the semiconductor element,
A plurality of protective members arranged in a state of being distributed in a peripheral portion of the functional surface and protruding from the functional surface, and formed on the holding member to house the protective member,
A plurality of protection member storage portions for guiding the protection member so as to be movable in and out of the functional surface; an urging member for urging the plurality of protection members in a protruding direction; And a conducting means for discharging to the, by the plurality of protective members, regulates the contact direction of an object that comes into contact with the functional surface from the outside and absorbs the impact at the time of contact,
In addition, static electricity generated on or near the functional surface is removed.

[0010] In the semiconductor device of the present invention, a plurality of protective members which can protrude and retract in the peripheral portion of the functional surface are dispersed and urged in the protruding direction, and each protective member is connected to the conducting means. Thus, the contact direction of an object that comes into contact with the functional surface from the outside is restricted by the plurality of protective members, the impact at the time of contact is absorbed, and static electricity generated on or near the functional surface is removed. Therefore, for example, it is possible to prevent foreign matter from colliding with the functional surface and damaging the functional surface unexpectedly when the semiconductor device is not used. Further, when the foreign matter is charged by static electricity or the like, it is possible to prevent the semiconductor element from being electrically damaged by discharging the charge before contacting or approaching the functional surface.

[0011]

Embodiments of a semiconductor device according to the present invention will be described below. Note that the embodiments described below are preferred specific examples of the present invention, and various technically preferable limitations are added.
In the following description, unless otherwise specified, the present invention is not limited to these embodiments. In the semiconductor device according to the present embodiment, a plurality of protection pins (protection members) are provided around the function surface, and the protection pins are urged by a spring to change the contact direction of an object that comes into contact with the function surface from outside. By restricting and absorbing the shock at the time of contact, the functional surface is mechanically protected. Further, by forming the protection pin with a conductive material and connecting it to ground or a power supply, static electricity generated on or near the functional surface is removed, and the functional surface is protected from electrostatic breakdown. Also,
In the case where an object (such as a finger) is always used close to the functional surface when operating the functional element, the above-described protection pin is linked to the switch so that the function element is automatically used only when the functional element is used. The switch is turned on to save unnecessary power consumption.

A typical example of a functional element capable of effectively utilizing the configuration according to the present embodiment is a fingerprint sensor. That is, by arranging the above-described protection pin around the sensor surface of the fingerprint sensor, even if foreign matter other than a finger unexpectedly comes into contact with the sensor surface, the protection pin blocks the movement of the foreign matter, Scratches or damage to the sensor can be prevented.
Further, when the protection pin is formed of a conductive material and is connected to a ground or a power source, when a fingerprint is recognized, the finger is pressed down to make contact with the sensor surface.

Thus, before the finger reaches the sensor surface, the finger comes into contact with the protection pin, so that the electric charge charged on this finger (human body) is discharged through the protection pin. Therefore, it is possible to prevent the static electricity from discharging to the fingerprint sensor and destroying the fingerprint sensor itself. In addition, a power switch for the fingerprint sensor is installed below the protection pin, and the power of the fingerprint sensor is turned on when the protection pin is pressed down, so that the power is turned on only when the finger touches the sensor surface I do. In this way, the switch is turned on only at the time of fingerprint authentication.
The trouble of turning off the power can be saved, and at the same time, unnecessary power consumption other than during use can be avoided.

Hereinafter, a specific embodiment in which a semiconductor device according to the present invention is applied to a fingerprint sensor will be described with reference to the drawings. FIG. 1 is a plan view showing a state in which the capacitance type fingerprint sensor according to the present embodiment is viewed from the sensor surface side. 2 and 3 are cross-sectional views showing the internal structure of the fingerprint sensor shown in FIG. 1. FIG. 2 is a cross-sectional view taken along line AA of FIG. 1, and FIG.
FIG. 7 is a sectional view taken along line BB of FIG. FIG. 4 is an enlarged partial cross-sectional view showing a portion provided with the protection pin of FIG. This fingerprint sensor has the same fingerprint recognition semiconductor chip 101 as the conventional fingerprint sensor shown in FIG. 6, and a fingerprint recognition surface (hereinafter, also referred to as a sensor surface) 101A of the fingerprint recognition semiconductor chip 101 is exposed. In this state, a portion of the wire bonding connecting the semiconductor chip 101 for fingerprint recognition and the lead 103 is sealed with a mold resin 102 made of, for example, a thermosetting resin.

In the mold resin 102 around the fingerprint recognition surface 101A of the fingerprint recognition semiconductor chip 101, a storage hole 104 as a protection member storage portion is opened. Protection pins 105 are stored. The protection pin 105 is formed of a conductive material such as a metal, is guided by the inner peripheral portion of the storage hole 104, and is movable in a direction perpendicular to the fingerprint recognition surface (a direction in which the protection surface comes out of the function surface). It is mounted in a state. The distal end of the protection pin 105 protrudes outward, and the base end of the protection pin 105 is provided with a retaining portion 105A. Further, a compression coil spring 106 as an urging member is disposed inside the storage hole 104. The compression coil spring 106 is arranged on the outer periphery of the protection pin 105, applies a spring force in the axial direction of the protection pin 105, and urges the protection pin 105 in a protruding direction.

A ground wire 107 as a conducting means is connected to the base end of the protection pin 105, and is connected to a ground terminal (not shown). The storage hole 10
A power switch 108 is provided at the bottom of the power switch 4.
When the protection pin 105 is operated by a finger or the like and moves in a direction of being immersed, the power switch 108 is pressed and turned on by the base end of the protection pin 105 to turn on the power supply of the fingerprint sensor. In a state where the operation of the protection pin 105 is released, the protection pin 105 is held in a protruding state by the spring force of the compression coil spring 106,
The power switch 108 is turned off. Note that such power switches 108 may not be provided in all the storage holes 104 but may be provided, for example, every other one.

Next, the operation of the fingerprint sensor as described above will be described. FIG. 5 is a cross-sectional view showing a state where the fingerprint sensor is operated with a finger. First, during the fingerprint recognition operation, as shown in FIG.
At this time, the protection pin 105 around the sensor surface 101A is pressed down by the finger 109. The pushed down protection pin 105 pushes down the projection of the switch 108 to turn on the fingerprint sensor. Further, when the finger 109 approaches, the finger 109 first touches the protection pin 105. Therefore, even if static electricity is accumulated in the human body, the accumulated charge is reduced to the protection pin 105.
Is discharged through. Therefore, the semiconductor chip 101
Is not destroyed by static electricity. Also, at times other than fingerprint recognition, since the protection pin 105 protrudes above the sensor surface, if a finger or a foreign substance unexpectedly approaches other than movement perpendicular to the sensor surface 101A, The protection pin 105 does not interfere with the sensor surface 101A. That is, the possibility that a finger or a foreign substance unexpectedly contacts the sensor surface 101A and damages or damages the sensor surface 101A can be greatly reduced.

As described above, according to the semiconductor device for fingerprint recognition according to the present embodiment, when not in use, the finger 109 or the foreign matter accidentally approached by the protection pin 105 protruding around the fingerprint recognition surface. No longer collides against the fingerprint recognition surface 101A unintentionally.
It is possible to prevent mechanical damages such as scratches from being generated. In use, even when the finger 109 is charged with static electricity, the accumulated charge is discharged through the pin 105 when the finger 109 pushes down the pin 105, so that the fingerprint recognition semiconductor chip 101 is charged by the static electricity. Troubles that cause electrical damage can also be prevented. Further, by configuring the power switch 108 of the semiconductor device for fingerprint recognition to operate in conjunction with the vertical movement of the protection pin 105, the troublesome operation of the switch when operating the semiconductor device for fingerprint recognition is eliminated. It is possible to solve the problem that the power is inadvertently turned on when not in use. In the above, an example in which the present invention is applied to a fingerprint sensor has been described. However, the present invention is not limited to this, and is widely applied to a semiconductor device having a functional surface configured by exposing a part of a semiconductor element to the outside. What you get. Also, the specific structures of the protection member and the protection member storage section are not limited to the above-described embodiment, but can be appropriately modified.

[0019]

As described above, according to the semiconductor device of the present invention, a plurality of protective members which can protrude and retract in the peripheral portion of the functional surface are distributed, and each protective member is urged in the projecting direction.
By connecting each protection member to the conducting means, the plurality of protection members regulate the contact direction of the object that comes into contact with the functional surface from the outside, absorb the impact at the time of contact, and close the functional surface or the vicinity thereof. The generated static electricity was removed. Therefore, for example, there is an effect that it is possible to prevent a foreign substance from unexpectedly colliding with the functional surface and damaging the functional surface when the semiconductor device is not used. Further, when the foreign matter is charged by static electricity or the like, there is an effect that electric charge can be discharged before contacting or approaching the functional surface to prevent electrical damage to the semiconductor element.

[Brief description of the drawings]

FIG. 1 is a plan view showing a state in which a capacitance type fingerprint sensor according to an embodiment of the present invention is viewed from a sensor surface side.

FIG. 2 is an AA diagram showing the internal structure of the fingerprint sensor shown in FIG. 1;
It is a line sectional view.

FIG. 3 is a BB diagram showing the internal structure of the fingerprint sensor shown in FIG. 1;
It is a line sectional view.

FIG. 4 is an enlarged partial cross-sectional view showing a portion provided with a protection pin of FIG. 3;

FIG. 5 is a cross-sectional view showing a state when the fingerprint sensor shown in FIG. 1 is operated with a finger.

FIG. 6 is a cross-sectional view showing the structure of a conventional capacitance fingerprint sensor.

FIG. 7 is a partial cross-sectional view showing an enlarged internal structure of the fingerprint sensor shown in FIG. 6;

8 is a circuit diagram showing a configuration of a detection signal extracting unit in the fingerprint sensor shown in FIG.

[Explanation of symbols]

Reference numeral 101: semiconductor chip, 101A: fingerprint recognition surface (sensor surface), 102: mold resin, 103: lead, 104: storage hole, 105: protection pin, 106
... compression coil spring, 107 ... ground wire, 108 ... power switch, 109 ... finger.

Claims (6)

[Claims] 1. A semiconductor device having a functional surface in which a part of a semiconductor element is exposed to the outside, a holding member for holding the semiconductor element in a state where the functional surface is exposed, and a periphery of the functional surface A plurality of protection members that are arranged in a distributed manner and protruded from the functional surface; and a direction in which the protection member is formed on the holding member and accommodates the protection member, and the protective member protrudes and retracts from the functional surface. A plurality of protection member storage portions that movably guide the plurality of protection members, a biasing member that biases the plurality of protection members in a protruding direction, and a conduction unit that discharges static electricity generated in the protection member to the outside, The plurality of protection members regulate the contact direction of an object that comes into contact with the functional surface from the outside, absorb an impact at the time of contact, and remove static electricity generated on or near the functional surface, Wherein a and. 2. The semiconductor device according to claim 1, wherein the protection member is formed in a pin shape, and is housed in the protection member housing so as to be movable in an axial direction of the pin. 3. The semiconductor device according to claim 1, wherein said functional surface is a sensor surface of a capacitance type fingerprint sensor. 4. The semiconductor device according to claim 1, wherein said urging member is a coil spring. 5. The semiconductor device according to claim 1, wherein said conduction means is a member for electrically connecting said protection member to ground or a power supply. 6. The semiconductor device according to claim 1, further comprising a switch that is activated by moving the protection member.