Patent Application
20080177353
1. Field of the Invention
The present invention relates to a cochlear implant device, an extracorporeal sound collector, and a cochlear implant system having each of them.
2. Description of the Related Art
A cochlear implant system is a device by which an electrical signal is directly applied to an inner ear (a cochlea) to make a brain perceive sound. The cochlear implant system has a structure formed of two main parts: a speech processor (referred to as an extracorporeal sound collector in this specification) and an inner ear electrode (referred to as a cochlear implant device in this specification). The speech processor (extracorporeal sound collector) converts a detected external sound into an electrical signal and transmits it to the inner ear electrode (cochlear implant device). The inner ear electrode (cochlear implant device) which receives the electrical signal is to provide a stimulus from an electrode inserted inside a cochlea to an auditory nerve. By use of such a cochlear implant system, a hearing impairment where a conventional hearing aid has not been supplied can be improved (Patent Document 1: Japanese Published Patent Application No. 2006-204646 and Patent Document 2: Japanese Translation of PCT International Application No. 2004-527194).
A cochlear implant device performs wireless communication by an electromagnetic induction method from an extracorporeal sound collector and receives a supply of power. Accordingly, the cochlear implant device does not have a power source such as a cell. Specifically, a coil antenna of an extracorporeal sound collector is arranged so as to be coupled to a coil antenna of a cochlear implant through skin by electromagnetic coupling. The antenna portion of the extracorporeal sound collector is referred to as a headpiece and is a circle having a diameter of about 3 cm, a thickness of about 8 mm, and a weight of about 5 g. This headpiece is used by being attached with a magnet so as to be opposed to the coil antenna of the cochlear implant that is embedded in a scalp behind an ear with skin in between the headpiece and the coil antenna.
The extracorporeal sound collector includes the headpiece, a sound collecting microphone, a signal processor, and the like and operates with a cell as a power source. In the case of one type of extracorporeal sound collector in which a sound collecting microphone and a signal processor are separated from each other, the signal processor is used by being placed in a breast pocket or fixed to a belt, and the sound collecting microphone is used by being worn on an ear. The weight of the sound collecting microphone is about 5 g to 10 g. Meanwhile, in the case of another type of extracorporeal sound collector in which a sound collecting microphone and a signal processor are formed integrally, the extracorporeal sound collector is used by being worn on an ear or fixed to a belt or the like so as to be exposed to external. For example, in the case where an extracorporeal sound collector is used by being worn on an ear, weight placed on the ear is about 12 g.
However, there are some major problems with the cochlear implant system in the wearing of a headpiece. For example, one problem is with how the headpiece feels while it is being used. In the case of wearing a headpiece, the strength of a magnet that is used for attachment is limited. Although some of the hair over which the headpiece is attached need not be shaved off, when the headpiece is placed over the hair, the headpiece is unstable depending on the amount of hair. Therefore, the headpiece cannot be worn properly depending on the hairstyle and the thickness of the skin. Furthermore, there is a case in which unnatural discomfort occurs due to attachment while the headpiece is worn and a case in which a hairstyle cannot be chosen freely.
In addition, a speech processor which is used by being worn on an ear may be broken because of moisture from sweat, hair, dust, or the like, in some cases.
A speech processor which is used by being worn on the ear is integrally formed with a sound collecting microphone and a signal processor, and the speech processor can be used for from 60 hours to 80 hours with one battery change. However, because such a speech processor has a relatively high output and needs to be small in size and lightweight, a zinc-air cell used exclusively by the speech processor is required to be used. This dedicated cell is disposable and incurs maintenance costs while being used. Furthermore, the range for temperature and humidity in which the dedicated cell can be used is narrow, and the dedicated cell cannot be used at a high temperature, at a low temperature, in high humidity, or in a dry state.
In the case where a speech processor whose signal processor is placed in a breast pocket and whose sound collecting microphone is worn on an ear is used, a headpiece, the sound collecting microphone, and the signal processor are connected to one another with a cable. This cable disturbs operations of a user, and the cable may be cut so that the speech processor is broken in some cases. For this reason, a user often carries a spare cable.
With the above wearing method, because the speech processor (extracorporeal sound collector) needs to be removed when a user enters water, such as when bathing or swimming, a cochlear implant system cannot be used.
In view of the foregoing problems, an object of the present invention is to provide a cochlear implant system which is easy to use with little interference with daily activities.
One feature of the present invention is a cochlear implant device including an inner ear electrode, an information processing circuit, a transmitter/receiver circuit, a charging circuit, and a battery, and the battery is charged with electromagnetic waves received by the transmitter/receiver circuit through the charging circuit. In addition, the power stored in the battery is supplied to the cochlear implant device. Further, the electromagnetic waves received by the transmitter/receiver circuit are converted into a signal by the information processing circuit, and the signal is provided from the inner ear electrode to stimulate the auditory nerve.
Another feature of the present invention is an extracorporeal sound collector including a microphone, an external input circuit, an information processing circuit, a transmitter/receiver circuit, a charging circuit, and a battery, and sounds detected by the microphone are converted into a signal by the information processing circuit, the signal is transmitted by the transmitter/receiver circuit to a cochlear implant device, along with electromagnetic waves of power with which the battery is charged through the transmitter/receiver circuit being transmitted to the cochlear implant device.
Another feature of the present invention is a cochlear implant system including a cochlear implant device having an inner ear electrode, a first information processing circuit, a first transmitter/receiver circuit, a first charging circuit, and a first battery as well as an extracorporeal sound collector having a microphone, an external input circuit, a second information processing circuit, a second transmitter/receiver circuit, a second charging circuit, and a second battery. In the first transmitter/receiver circuit and the second transmitter/receiver circuit, signals related to sounds detected by the microphone are transmitted and received, along with power stored in the second battery being supplied to the first battery by use of electromagnetic waves.
Here, the above first information processing circuit includes an amplifier circuit, a central arithmetic processing circuit, and the like. In addition, the above second information processing circuit includes an external input circuit, an amplifier circuit, a central arithmetic processing circuit, and the like.
Here, the first transmitter/receiver circuit that is provided in the cochlear implant device and the second transmitter/receiver circuit that is provided in the extracorporeal sound collector each include at least one antenna, a capacitor, a demodulation circuit, a decoding circuit, a logic operation/control circuit, a memory circuit, an encoding circuit, and a modulation circuit.
The first charging circuit that is provided in the cochlear implant device includes a rectifier circuit which rectifies an induced electromotive force that is generated in the antenna which is included in the first transmitter/receiver circuit that is provided in the cochlear implant, a current/voltage control circuit, and a charge control circuit. The second charging circuit that is provided in the extracorporeal sound collector includes a rectifier circuit which rectifies power inputted from an external power source, a current/voltage control circuit, and a charge control circuit.
In the cochlear implant system of the present invention, the inner ear electrode is connected to the first amplifier circuit that is provided in the cochlear implant device, and the first amplifier circuit is connected to the first central arithmetic processing circuit that is provided in the cochlear implant device. In addition, the first transmitter/receiver circuit that is provided in the cochlear implant device is connected to the first central arithmetic processing circuit that is provided in the cochlear implant device and the first charging circuit that is provided in the cochlear implant device, and the first charging circuit that is provided in the cochlear implant device is connected to the first battery that is provided in the cochlear implant device. Further, the first battery that is provided in the cochlear implant device supplies power to the cochlear implant device.
The microphone that is included in the extracorporeal sound collector is connected to the external input circuit, and the external input circuit is connected to the second amplifier circuit that is provided in the extracorporeal sound collector. However, the extracorporeal sound collector may have a structure in which the microphone is connected to an amplifier circuit without any external input circuit being provided. In addition, the second amplifier circuit that is provided in the extracorporeal sound collector is connected to the second central arithmetic processing circuit that is provided in the extracorporeal sound collector, and the second transmitter/receiver circuit that is provided in the extracorporeal sound collector is connected to the second central arithmetic processing circuit that is provided in the extracorporeal sound collector and the second charging circuit that is provided in the extracorporeal sound collector. Further, the second charging circuit that is provided in the extracorporeal sound collector is connected to the second battery that is provided in the extracorporeal sound collector, and the second battery that is provided in the extracorporeal sound collector supplies power to the extracorporeal sound collector.
Here, the second battery that is provided in the extracorporeal sound collector is charged using the external power source through the second charging circuit that is provided in the extracorporeal sound collector. In addition, as a method of charging of the first battery that is provided in the cochlear implant device, electromagnetic waves transmitted from the second transmitter/receiver circuit that is provided in the extracorporeal sound collector are received by the first transmitter/receiver circuit that is provided in the cochlear implant device, and the first battery is charged through the first charge control circuit that is provided in the cochlear implant device.
As described above, the cochlear implant device of the present invention includes a battery which is a self-driving power source that is not originally included in the device. Furthermore, a method of communication with the extracorporeal sound collector is not limited to being an electromagnetic coupling method, and a communication distance with the extracorporeal sound collector can be extended when the cochlear implant device has a structure in which communication is performed by use of electromagnetic waves. Accordingly, a user of a cochlear implant system can use an extracorporeal sound collector at a place other than one's head and be released from the difficulty in wearing a headpiece on one's head. As a result of this, the daily life of a user of a cochlear implant system can be improved.
Hereinafter, embodiment modes of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the following description. As can be easily understood by those skilled in the art, the modes and details of the present invention can be changed in various ways without departing from the spirit and scope of the present invention. Thus, the present invention should not be interpreted as being limited to the following description of the embodiment modes. Note that the same reference numerals are commonly used to denote the same components among different drawings in structures of the present invention explained below.
In this embodiment mode of the present invention, a cochlear implant device, an extracorporeal sound collector, and a cochlear implant system having each of them will be described. A cochlear implant system 101 of the present invention includes a cochlear implant device 102 which is embedded in a body and transmits information for sounds to an auditory nerve, and an extracorporeal sound collector 103 which detects ambient sounds from outside the body and transmits them to the cochlear implant device (see
First, the cochlear implant device 102 will be described. The cochlear implant device 102 of the cochlear implant system 101 includes an inner ear electrode 104, an amplifier circuit 105, a central arithmetic processing circuit 106, a transmitter/receiver circuit 107, a charging circuit 108, and a battery 109.
The inner ear electrode 104 provides electric stimulation to the auditory nerve of an inner ear. The amplifier circuit 105 amplifies a signal that is to be transmitted to the inner ear electrode 104. The central arithmetic processing circuit 106 performs information processing in order to communicate with the extracorporeal sound collector 103. The transmitter/receiver circuit 107 performs wireless communication with the extracorporeal sound collector 103. The charging circuit 108 charges the battery with electromagnetic waves from the extracorporeal sound collector 103 as power. The battery supplies power to the inner ear electrode 104, the amplifier circuit 105, the central arithmetic processing circuit 106, the transmitter/receiver circuit 107, the charging circuit 108, and the like of the cochlear implant device 102.
Here, the transmitter/receiver circuit 107 that is provided in the cochlear implant device is a circuit which performs wireless communication with the extracorporeal sound collector 103, as shown in
The charging circuit 108 that is provided in the cochlear implant device includes a rectifier circuit 207 which rectifies an induced electromotive force generated in the antenna, a current/voltage control circuit (also referred to as a regulator) 208, and a charge control circuit 209, as shown in
The battery 109 charged in this manner supplies power to each circuit, such as the inner ear electrode 104, the amplifier circuit 105, the central arithmetic processing circuit 106, the transmitter/receiver circuit 107, and the charging circuit 108, in order to drive the entire cochlear implant device 102. In this way, the cochlear implant device 102 including a wireless communication function includes a battery which is a self-driving power source that is not originally included in the device. Furthermore, a method of communication with the extracorporeal sound collector is not limited to being an electromagnetic coupling method, and a communication distance of wireless communication can be extended when the cochlear implant device has a structure in which communication is performed by use of electromagnetic waves.
The amplifier circuit 105, the central arithmetic processing circuit 106, the transmitter/receiver circuit 107, and the charging circuit 108 of the cochlear implant device 102 may each be formed of a field effect transistor (FET) or a thin film transistor by use of a single crystal silicon substrate or an SOI substrate. Alternatively, a given circuit may be formed of a combination of a field effect transistor and a thin film transistor. When thin film transistors are used for the above circuits, the cochlear implant device can be made thinly.
Next, the extracorporeal sound collector 103 will be described. The extracorporeal sound collector 103 of the cochlear implant system 101 includes a microphone 110, an external input circuit 111, an amplifier circuit 112, a central arithmetic processing circuit 113, a transmitter/receiver circuit 114, a charging circuit 115, and a battery 116. The microphone 110 detects external sounds. A signal from the microphone 110 or from another external device is inputted to the external input circuit 111. However, a structure may be used in which the extracorporeal sound collector 103 does not include the external input circuit 111 and the microphone 110 is connected to the amplifier circuit 112, as well. The amplifier circuit 112 amplifies an analog audio signal that is inputted from the microphone 110 or the like. The central arithmetic processing circuit 113 decomposes the audio signal that is amplified by the amplifier circuit 112 into each frequency and changes it into an electric signal that is to be used by the inner ear electrode 104 of the cochlear implant device 102. The transmitter/receiver circuit 114 performs wireless communication with the cochlear implant device 102. The charging circuit 115 supplies power supplied from a cell or from an external power source to the battery 116, and the battery 116 supplies power to the extracorporeal sound collector 103.
Here, the transmitter/receiver circuit 114 can have a structure that is almost the same as that of the transmitter/receiver circuit 107 that is provided in the cochlear implant, as shown in
The external input circuit 111, the amplifier circuit 112, the central arithmetic processing circuit 113, the transmitter/receiver circuit 114, and the charging circuit 115 of the extracorporeal sound collector 103 may each be formed of a field effect transistor (FET) or a thin film transistor by use of a single crystal silicon substrate or an SOI substrate. Alternatively, a given circuit may be formed of a combination of a field effect transistor and a thin film transistor. The microphone 110 may be formed using a MEMS device. When a MEMS device is used for the microphone 110, a weak signal can also be detected; therefore, the microphone is small and high sensitivity, and the microphone can detect a weak sound.
Next, a usage mode of the cochlear implant system 101 of the present invention will be described. As shown in
Note that the extracorporeal sound collector 103 is desirably fixed so that the microphone is exposed in order that external sounds can be detected with high accuracy.
The cochlear implant device 102 is embedded between an external auditory canal 122 and a skull 123 and between skin 124 and the skull 123 (see
The cochlear implant system 101 provided in this way functions as described hereinafter. First, external sounds are detected by the microphone 110 that is provided in the extracorporeal sound collector. Then, information for the external sounds is amplified by the amplifier circuit 112 through the external input circuit 111; analog-to-digital conversion is performed; and decomposition is performed into each frequency to be processed by the central arithmetic processing circuit 113 into a signal required by the cochlear implant device 102. Then, a signal is transmitted from the transmitter/receiver circuit 114 to the cochlear implant device 102.
Next, in the cochlear implant device 102, a signal transmitted from the extracorporeal sound collector 103 is received by the transmitter/receiver circuit 107. Then, signal processing is performed by the central arithmetic processing circuit 106, a signal is amplified by the amplifier circuit 105, and an auditory nerve 125 is stimulated by the inner ear electrode 104. Accordingly, a user of the cochlear implant device can perceive sounds detected by the microphone.
In addition, a function related to a supply of power of the cochlear implant system 101 of the present invention is as described hereinafter. First, in the extracorporeal sound collector 103, power is supplied from a cell or from an external power source to the charging circuit 115, and the charging circuit charges the battery 116. The charged battery 116 supplies power to each circuit of the extracorporeal sound collector 103 so as to drive the extracorporeal sound collector 103, along with the charged battery 116 supplying power to the transmitter/receiver circuit 114 so as to supply power to the cochlear implant device 102. The transmitter/receiver circuit 114 that is provided in the extracorporeal sound collector transmits electromagnetic waves in order to supply power to the cochlear implant device 102.
Next, in the transmitter/receiver circuit 107 that is provided in the cochlear implant device, electromagnetic waves transmitted from the extracorporeal sound collector 103 are received, the power is rectified by the charging circuit 108, and the battery 109 is charged. Then, the charged battery 109 supplies power to each circuit of the cochlear implant device 102 so as to drive the cochlear implant device 102.
Note that the cochlear implant device 102 can be charged wirelessly from the extracorporeal sound collector 103 as described above; however, the cochlear implant device 102 can have a structure where it can be charged by a wireless charging device built into an article for daily life such as a pillow, a bed, a hat, or furniture.
The cochlear implant device 102 of the present invention includes a battery which is a self-driving power source that is not originally included in the device. Furthermore, a method of communication with the extracorporeal sound collector is not limited to being an electromagnetic coupling method, and a communication distance can be extended when the cochlear implant device has a structure in which communication is performed by use of electromagnetic waves. Therefore, even when a distance between the extracorporeal sound collector 103 and the cochlear implant device 102 increases to some extent, sounds can be heard.
Furthermore, a headpiece need not be mounted on the head, worn on the ear, or the like, and a user can be released from discomfort or difficulty in wearing the extracorporeal sound collector 103, in particular, a transmitter/receiver portion (headpiece), in the vicinity of an ear.
The cochlear implant device 102 of the present invention has a structure with a battery which can be charged wirelessly. The cochlear implant device 102 and the extracorporeal sound collector 103 are made to be waterproof, by which swimming and bathing while the extracorporeal sound collector 103 is being worn can be enabled.
In this embodiment mode, an example is shown in which the cochlear implant system 101 is used by use of a function included in the extracorporeal sound collector 103 of the present invention.
The extracorporeal sound collector 103 of the present invention includes the external input circuit 111. A radio, a cellular phone 200, a music player, or the like is connected to this external input circuit 111 so that a user of the cochlear implant system 101 can hear sounds outputted from the connected device (see
For example, when information for sounds input from the outside is an analog signal, a structure can be used in which the external input circuit 111 is provided between the microphone 110 and the amplifier circuit 112. When information for sounds is input by a digital signal, a structure can be used in which the external input circuit 111 and the central arithmetic processing circuit 113 are connected to each other. Needless to say, a structure corresponding to an input of either an analog signal or a digital signal can also be used.
In this manner, even if a person is hard-of-hearing, he or she can enjoy entertainment such as music or radio or can communicate with another person by cellular phone by use of the cochlear implant system 101 of the present invention.
Note that this embodiment mode can be freely combined with the above embodiment mode.
In this embodiment mode, an example of a method for manufacturing the cochlear implant device described in Embodiment Modes 1 and 2 will be described with reference to
First, as shown in
Further, the substrate 1901 may be a glass substrate, a quartz substrate, a metal substrate (e.g., a stainless steel substrate or the like), a ceramic substrate, or a semiconductor substrate, such as a Si substrate. Alternatively, a plastic substrate formed of polyethylene terephthalate (PET), polyether sulfone (PES), acrylic, or the like can be used. Note that in this step, the separation layer 1903 is provided over an entire surface of the substrate 1901 with the insulating film 1902 interposed therebetween; however, if necessary, the separation layer may be selectively provided by use of a photolithography method after providing the separation layer over an entire surface of the substrate 1901.
The insulating film 1902 and the insulating film 1904 are formed using an insulating material such as silicon oxide, silicon nitride, silicon oxynitride, or silicon nitride oxide, by a CVD method, a sputtering method, or the like. For example, when the insulating film 1902 and the insulating film 1904 have a two-layer structure, preferably a silicon nitride oxide film is formed as a first insulating film and a silicon oxynitride film is formed as a second insulating film. Alternatively, a silicon nitride film may be formed as a first insulating film and a silicon oxide film may be formed as a second insulating film. The insulating film 1902 serves as a blocking layer which prevents an impurity element from the substrate 1901 from being mixed into the separation layer 1903 or an element formed thereover. The insulating film 1904 serves as a blocking layer which prevents an impurity element from the substrate 1901 or the separation layer 1903 from being mixed into an element formed thereover. By forming the insulating films 1902 and 1904 which serve as blocking layers in this manner, an element formed thereover can be prevented from being adversely affected by an alkali metal such as Na or an alkali earth metal from the substrate 1901, or an impurity element included in the separation layer 1903. Note that when quartz is used as the substrate 1901, the insulating films 1902 and 1904 may be omitted from the structure.
As the separation layer 1903, a metal film, a stacked-layer structure including a metal film and a metal oxide film, or the like can be used. As the metal film, a single-layer structure or a stacked-layer structure is formed using a film formed of any of the elements tungsten (W), molybdenum (Mo), titanium (Ti), tantalum (Ta), niobium (Nb), nickel (Ni), cobalt (Co), zirconium (Zr), zinc (Zn), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and silicon (Si) or of an alloy material or a compound material containing such an element as a main constituent. These materials can be formed by use of a sputtering method, various CVD methods, such as a plasma CVD method, or the like. As the stacked-layer structure including a metal film and a metal oxide film, after the aforementioned metal film is formed, plasma treatment in an oxygen atmosphere or an N2O atmosphere, or heat treatment in an oxygen atmosphere or an N2O atmosphere is performed, so that oxide or oxynitride of the metal film can be formed on a surface of the metal film. For example, when a tungsten film is formed as the metal film by a sputtering method, a CVD method, or the like, plasma treatment is performed on the tungsten film so that a metal oxide film formed of tungsten oxide can be formed on a surface of the tungsten film. In this case, oxide of tungsten is expressed as WOx, where x is 2 to 3, and there are cases where x is 2 (WO2), cases where x is 2.5 (W2O5), cases where x is 2.75 (W4O11), cases where x is 3 (WO3), and the like. When forming the oxide of tungsten, there is no particular limitation on the value of x, and which oxide is to be formed may be determined in accordance with an etching rate or the like. Alternatively, for example, after a metal film (e.g., tungsten) is formed, an insulating film such as silicon oxide may be provided over the metal film by a sputtering method, and metal oxide may also be formed over the metal film (e.g., tungsten oxide over tungsten). In addition, as plasma treatment, the above high-density plasma treatment may also be performed, for example. Further, besides the metal oxide film, metal nitride or metal oxynitride may also be used. In such a case, plasma treatment or heat treatment under a nitrogen atmosphere or an atmosphere of nitrogen and oxygen may be performed on the metal film.
The semiconductor film 1905 is formed with a thickness of 10 to 200 nm (preferably, 30 to 150 nm) by a sputtering method, an LPCVD method, a plasma CVD method, or the like.
Next, as shown in
Note that the gate insulating film 1906 is formed using an insulating material such as silicon oxide, silicon nitride, silicon oxynitride, or silicon nitride oxide, by a CVD method, a sputtering method, or the like. For example, when the gate insulating film 1906 has a two-layer structure, preferably a silicon oxynitride film is formed as a first insulating film and a silicon nitride oxide film is formed as a second insulating film. Alternatively, a silicon oxide film may be formed as the first insulating film and a silicon nitride film may be formed as the second insulating film.
An example of a step for manufacturing the crystalline semiconductor films 1905a to 1905f will be briefly described hereinafter. A semiconductor layer having an amorphous structure is formed by a known method (a sputtering method, an LPCVD method, a plasma CVD method, or the like) and then crystallized by known crystallization treatment (laser crystallization, thermal crystallization, thermal crystallization using a catalyst such as nickel, or the like) so that a crystalline semiconductor layer is obtained, and the crystalline semiconductor layer is patterned into a desired shape after a resist mask is formed using a photomask so that the crystalline semiconductor films 1905a to 1905f are formed.
Note that as a laser oscillator for crystallization, a continuous wave laser beam (a CW laser beam) or a pulsed wave laser beam (a pulsed laser beam) can be used. As a laser beam which can be used here, a laser beam emitted from one or more of the following can be used: a gas laser, such as an Ar laser, a Kr laser, or an excimer laser; a laser whose medium is single crystalline YAG, YVO4, forsterite (Mg2SiO4), YAlO3, or GdVO4, to which one or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta has been added as a dopant; or polycrystalline (ceramic) YAQ Y2O3, YVO4, YAlO3, or GdVO4, to which one or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta has been added as a dopant; a glass laser; a ruby laser; an alexandrite laser; a Ti:sapphire laser; a copper vapor laser; or a gold vapor laser. Crystals with a large grain size can be obtained by irradiation with fundamental waves of such laser beams or second to fourth harmonics of the fundamental waves. For example, the second harmonic (532 nm) or the third harmonic (355 nm) of an Nd:YVO4 laser (fundamental wave of 1064 nm) can be used. In this case, a power density of approximately 0.01 to 100 MW/cm2 (preferably, 0.1 to 10 MW/cm2) is necessary. Irradiation is conducted with a scanning rate of approximately 10 to 2000 cm/sec. Note that a laser using, as a medium, single crystalline YAG YVO4, forsterite (Mg2SiO4), YAlO3, or GdVO4, to which one or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta has been added as a dopant, or polycrystalline (ceramic) YAG Y2O3, YVO4, YAlO3, or GdVO4, to which one or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta has been added as a dopant; an Ar ion laser; or a Ti:sapphire laser, can be continuously oscillated. Furthermore, pulse oscillation thereof can be performed at a repetition rate of 10 MHz or more by performing Q-switching operation, mode locking, or the like. When a laser beam is oscillated at a repetition rate of 10 MHz or more, during the time in which a semiconductor film is melted by the laser beam and then solidifies, the semiconductor film is irradiated with a next pulse. Accordingly, unlike in a case of using a pulsed laser with a low repetition rate, a solid-liquid interface can be continuously moved in the semiconductor film; therefore, crystal grains which have grown continuously in a scanning direction can be obtained.
Alternatively, as the crystallization treatment of a semiconductor layer having an amorphous structure, a sequential lateral solidification method (SLS method) may be used. In an SLS method, a sample is irradiated with a pulsed excimer laser beam through a slit-shaped mask. This is a method for continuously forming a crystal by the artificially controlled super-lateral growth and can be conducted by performing crystallization displacing a relative position of the sample and the laser beam every shot by an approximately the same length to that of the crystal which is super-laterally grown.
Further, the above-described high-density plasma treatment may be performed on the crystalline semiconductor films 1905a to 1905f to oxidize or nitride surfaces thereof, to form the gate insulating film 1906. For example, the gate insulating film 1906 is formed by plasma treatment in which a mixed gas which contains a rare gas such as He, Ar, Kr, or Xe, and oxygen, nitrogen dioxide, ammonia, nitrogen, hydrogen, or the like, is introduced. When excitation of the plasma in this case is performed by introduction of a microwave, high density plasma can be generated at a low electron temperature. The surface of the semiconductor film can be oxidized or nitrided by oxygen radicals (OH radicals may be included) or nitrogen radicals (NH radicals may be included) generated by this high-density plasma.
By treatment using such high-density plasma, an insulating film with a thickness of 1 to 20 nm, typically 5 to 10 nm, is formed over the semiconductor film. Because the reaction in this case is a solid-phase reaction, interface state density between the insulating film and the semiconductor film can be made very low. Because such high-density plasma treatment oxidizes (or nitrides) a semiconductor film (crystalline silicon, or polycrystalline silicon) directly, the insulating film can be formed with very little unevenness in its thickness. In addition, since crystal grain boundaries of crystalline silicon are also not strongly oxidized, very favorable conditions result. That is, by the solid-phase oxidation of the surface of the semiconductor film by the high-density plasma treatment shown here, an insulating film with good uniformity and low interface state density can be formed without excessive oxidation at crystal grain boundaries.
Note that as the gate insulating film 1906, just an insulating film formed by the high-density plasma treatment may be used, or an insulating film of silicon oxide, silicon oxynitride, silicon nitride, or the like may be formed thereover by a CVD method which employs plasma or a thermal reaction, to make stacked layers. In any case, when transistors include an insulating film formed by high-density plasma in a part of a gate insulating film or in the whole of a gate insulating film, unevenness in characteristics can be reduced.
Furthermore, in the crystalline semiconductor films 1905a to 1905f which are obtained by crystallizing a semiconductor film by irradiation with a continuous wave laser beam or a laser beam oscillated at a repetition rate of 10 MHz or more which is scanned in one direction, crystals grow in the scanning direction of the beam. When transistors are arranged so that the scanning direction is aligned with the channel length direction (the direction in which a carrier flows when a channel formation region is formed) and the above-described gate insulating layer is used in combination with the transistors, thin film transistors (TFTs) with less variation in characteristics and high electron field-effect mobility can be obtained.
Next, a first conductive film and a second conductive film are stacked over the gate insulating film 1906. Here, the first conductive film is formed with a thickness of 20 to 100 nm using a CVD method, a sputtering method, or the like. The second conductive film is formed with a thickness of 100 to 400 nm. The first conductive film and the second conductive film are formed using an element such as tantalum (Ta), tungsten (W), titanium (Ti), molybdenum (Mo), aluminum (Al), copper (Cu), chromium (Cr), or niobium (Nb), or using an alloy material or a compound material containing such an element as a main constituent. Alternatively, they are formed using a semiconductor material typified by polycrystalline silicon doped with an impurity element such as phosphorus. As examples of a combination of the first conductive film and the second conductive film, a tantalum nitride film and a tungsten film, a tungsten nitride film and a tungsten film, a molybdenum nitride film and a molybdenum film, and the like can be given. Because tungsten and tantalum nitride have high heat resistance, heat treatment for thermal activation can be performed after the first conductive film and the second conductive film are formed. In addition, in the case of using a three-layer structure instead of a two-layer structure, a stacked-layer structure including a molybdenum film, an aluminum film, and a molybdenum film may be used.
Next, a resist mask is formed using a photolithography method, and etching treatment for forming a gate electrode and a gate line is conducted, forming gate electrodes 1907 over the crystalline semiconductor films 1905a to 1905f. Here, an example in which the gate electrodes 1907 have a stacked-layer structure which includes a first conductive film 1907a and a second conductive film 1907b is described.
Next, as shown in
Next, an insulating film is formed so as to cover the gate insulating film 1906 and the gate electrodes 1907. The insulating film is formed as a single layer or stacked layers of a film containing an inorganic material such as silicon, oxide of silicon, or nitride of silicon, or a film containing an organic material such as an organic resin, by a plasma CVD method, a sputtering method, or the like. Next, the insulating film is selectively etched using anisotropic etching which etches mainly in a perpendicular direction, forming insulating films 1910 (also referred to as side walls) which are in contact with side surfaces of the gate electrodes 1907. The insulating films 1910 are used as masks for doping when LDD (lightly doped drain) regions are formed.
Next, using a resist mask formed by a photolithography method, the gate electrodes 1907, and the insulating films 1910 as masks, an impurity element which imparts n-type conductivity is added at a high concentration to the crystalline semiconductor films 1905a, 1905b, 1905d, and 1905f, to form n-type impurity regions 1911. Here, phosphorus (P) is used as an impurity element which imparts n-type conductivity, and it is selectively introduced into the crystalline semiconductor films 1905a, 1905b, 1905d, and 1905f such that they contain phosphorus (P) at a concentration of 1×1019 to 1×1020/cm3. Thus, the n-type impurity regions 1911, which have a higher concentration than the impurity regions 1908, are formed.
By the above-described steps, n-channel thin film transistors 1900a, 1900b, 1900d, and 1900f and p-channel thin film transistors 1900c and 1900e are formed, as shown in
Note that in the n-channel thin film transistor 1900a, a channel formation region is formed in a region of the crystalline semiconductor film 1905a which overlaps with the gate electrode 1907; the impurity regions 1911 which each form either a source region or a drain region are formed in regions which do not overlap with the gate electrode 1907 and the insulating films 1910; and low concentration impurity regions (LDD regions) are formed in regions which overlap with the insulating films 1910 and which are between the channel formation region and the impurity regions 1911. Further, the n-channel thin film transistors 1900b, 1900d, and 1900f are similarly provided with channel formation regions, low concentration impurity regions, and the impurity regions 1911.
Further, in the p-channel thin film transistor 1900c, a channel formation region is formed in a region of the crystalline semiconductor film 1905c which overlaps with the gate electrode 1907, and the impurity regions 1909 which each form either a source region or a drain region are formed in regions which do not overlap with the gate electrode 1907. Further, the p-channel thin film transistor 1900e is similarly provided with a channel formation region and the impurity regions 1909. Note that, here, the p-channel thin film transistors 1900c and 1900e are not provided with LDD regions; however, the p-channel thin film transistors may be provided with an LDD region, and the n-channel thin film transistor is not necessarily provided with an LDD region.
Next, as shown in
Note that before the insulating films 1912a and 1912b are formed or after one or more thin films of the insulating films 1912a and 1912b are formed, heat treatment is preferably conducted for recovering the crystallinity of the semiconductor film, for activating an impurity element which has been added to the semiconductor film, or for hydrogenating the semiconductor film. As the heat treatment, thermal annealing, a laser annealing method, an RTA method, or the like is preferably used.
The conductive films 1913 are formed as a single layer or stacked layers, using any of the elements aluminum (Al), tungsten (W), titanium (Ti), tantalum (Ta), molybdenum (Mo), nickel (Ni), platinum (Pt), copper (Cu), gold (Au), silver (Ag), manganese (Mn), neodymium (Nd), carbon (C), and silicon (Si), or an alloy material or a compound material containing one of the above-mentioned elements as a main constituent, by a CVD method, a sputtering method, or the like. An alloy material containing aluminum as a main constituent corresponds to, for example, a material which contains aluminum as a main constituent and also contains nickel, or an alloy material which contains aluminum as a main constituent and which also contains nickel and one or both of carbon and silicon. The conductive films 1913 preferably employ, for example, a stacked-layer structure including a barrier film, an aluminum-silicon film, and a barrier film, or a stacked-layer structure including a barrier film, an aluminum-silicon film, a titanium nitride film, and a barrier film. Note that a barrier film corresponds to a thin film formed from titanium, nitride of titanium, molybdenum, or nitride of molybdenum. Aluminum and aluminum silicon, which have low resistance and are inexpensive, are ideal materials for forming the conductive films 1913. Further, generation of a hillock of aluminum or aluminum silicon can be prevented when upper and lower barrier layers are formed. Furthermore, when the barrier film is formed from titanium, which is a highly-reducible element, even if a thin natural oxide film is formed over the crystalline semiconductor film, the natural oxide film is chemically reduced, so good contact with the crystalline semiconductor film can be obtained.
Next, an insulating film 1914 is formed so as to cover the conductive films 1913, and over the insulating film 1914, conductive films 1915a and 1915b, which are each electrically connected to the conductive films 1913 which form source electrodes and drain electrodes of the crystalline semiconductor films 1905a and 1905f, are formed. Further, conductive films 1916a and 1916b, which are each electrically connected to the conductive films 1913 which form source electrodes and drain electrodes of the crystalline semiconductor films 1905b and 1905e, are formed. Note that the conductive films 1915a and 1915b may be formed of the same material at the same time as the conductive films 1916a and 1916b. The conductive films 1915a and 1915b and the conductive films 1916a and 1916b can be formed using any of the materials that the conductive films 1913 can be formed of, as mentioned above.
Next, as shown in
The conductive films 1917, 1931a, and 1931b are formed from a conductive material, using a CVD method, a sputtering method, a printing method, such as a screen printing method or a gravure printing method, a droplet discharge method, a dispensing method, a plating method, or the like. The conductive material is any of the elements aluminum (Al), titanium (Ti), silver (Ag), copper (Cu), gold (Au), platinum (Pt), nickel (Ni), palladium (Pd), tantalum (Ta), and molybdenum (Mo), or an alloy material or a compound material containing one of the above-mentioned elements as a main constituent, and has a single-layer structure or a stacked-layer structure.
For example, in the case of using a screen printing method to form the conductive film 1917 which serves as an antenna, the conductive film 1917 can be provided by selectively printing a conductive paste in which conductive particles having a grain size of several nm to several tens of μm are dissolved or dispersed in an organic resin. As conductive particles, metal particles of one or more of any of silver (Ag), gold (Au), copper (Cu), nickel (Ni), platinum (Pt), palladium (Pd), tantalum (Ta), molybdenum (Mo), titanium (Ti), and the like; fine particles of silver halide; or dispersive nanoparticles can be used. In addition, as the organic resin included in the conductive paste, one or more organic resins selected from among organic resins which serve as a binder, a solvent, a dispersing agent, or a coating material for the metal particles can be used. An organic resin such as an epoxy resin or a silicone resin can be given as representative examples. Further, when the conductive film is formed, it is preferable to conduct baking after the conductive paste is applied. For example, in the case of using fine particles containing silver as a main constituent (e.g., the grain size is greater than or equal to 1 nm and less than or equal to 100 nm) as a material for the conductive paste, the conductive film can be obtained by curing by baking at a temperature in the range of 150° C. to 300° C. Alternatively, fine particles containing solder or lead-free solder as a main constituent may be used. In that case, preferably fine particles having a grain size of 20 μm or less are used. Solder and lead-free solder have advantages such as low cost.
Further, although not shown, when the conductive film 1917 which serves as an antenna are formed, another conductive film may be separately formed such that it is electrically connected to the amplifier circuit 105, and that conductive film may be used as a wiring connected to the inner ear electrode 104.
Note that the insulating layer 1918 can be provided by a CVD method, a sputtering method, or the like as a single-layer structure or a stacked-layer structure which includes an insulating film containing oxygen and/or nitrogen, such as silicon oxide, silicon nitride, silicon oxynitride, or silicon nitride oxide; or a film containing carbon, such as DLC (diamond-like carbon); or an organic material, such as epoxy, polyimide, polyamide, polyvinyl phenol, benzocyclobutene, or acrylic; or a siloxane material, such as a siloxane resin.
Next, as shown in
Next, in this embodiment mode, openings are formed in a layer (hereinafter referred to as an “element formation layer 1919”) that includes the thin film transistors 1900a to 1900f, the conductive film 1917, the insulating layer 1918, and the like by laser beam irradiation.
Next, as shown in
Next, as shown in
The conductive films 1934a and 1934b can be formed using a material and a manufacturing method which are similar to those used to form the conductive film 1917, as appropriate.
Note that, here, an example is shown in which the conductive films 1934a and 1934b are formed after the element formation layer 1919 is separated from the substrate 1901; however, the element formation layer 1919 may be separated from the substrate 1901 after the conductive films 1934a and 1934b are formed, as well.
The first housing 1921 is formed using a biologically inert material. Typically, a housing formed of a conductive material such as titanium, platinum, or gold or a housing formed of an insulating material such as an organic resin or a ceramic may be used. Furthermore, as the first housing 1921, a film formed using the above material may be used as well. When a film is used for the first housing 1921, the cochlear implant device 102, which is small and lightweight, is easily fitted to a body, and has little unevenness.
Next, as shown in
Next, as shown in
Next, as shown in
Furthermore, the surfaces of the first housing 1921 and the second housing 1922 are protected by a protective layer formed of silicon, fluorocarbon polymer, parylene, DLC, or the like, whereby the device is made safer for a body of a living thing.
As the first housing 1921 and the second housing 1922, materials (hereinafter referred to as antistatic materials) on which antistatic treatment for preventing static electricity or the like has been performed can be used. As a material that can prevent electrostatic charge, a metal, indium tin oxide (ITO), or a surfactant such as an amphoteric surfactant, a cationic surfactant, or a nonionic surfactant can be used. In addition to this, as an antistatic material, a resin material that contains a cross-linked copolymer having a carboxyl group and a quaternary ammonium base on its side chain or the like can be used. By attaching, mixing, or applying such a material to each of the housings, generation of static charge can be provided.
Note that the connection between the battery 109 and the charging circuit 108 and the connection between the inner ear electrode 104 and the amplifier circuit 105 may be made before the element formation layer 1919 is separated from the substrate 1901 (at a stage shown in
In a case where the battery is larger than the element, by forming a plurality of elements over one substrate, as shown in
According to the above-described steps, a cochlear implant device can be manufactured. Note that in this embodiment, a step in which separation is performed after forming elements such as thin film transistors over the substrate has been described; however, the substrate over which elements are formed may be used as a product without performing separation. Further, when elements such as thin film transistors are provided over a glass substrate, and the glass substrate is then polished on the side opposite to the surface over which the elements are provided; or when a semiconductor substrate such as Si or the like is used and MOS transistors are formed, and the semiconductor substrate is then polished, thinning and miniaturization of a cochlear implant device can be achieved.
This application is based on Japanese Patent Application serial No. 2006-354767 filed with Japan Patent Office on Dec. 28, 2006, the entire contents of which are hereby incorporated by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-354767 | Dec 2006 | JP | national |
