Fabricating condenser microphone and condenser microphone

A first semiconductor chip includes a fixed electrodeof forming, on the first semiconductor substrate, a
formed on a first semiconductor substrate and adetection circuit for detecting a signal from the
plurality of first metal spacers formed on a firstcondenser microphone. Furthermore,the detection
interlayer dielectric. A second semiconductor chipcircuit preferably includes a MOS transistor, and the
includes a vibrating electrode formed on a secondfixed electrode is preferably formed simultaneously
semiconductor substrate and a plurality of secondwith a gate electrode of the MOS transistor.
metal spacers formed on a second interlayer dielectric.A condenser microphone of the present invention
The first and second semiconductor chips areincludes a fixed electrode, a vibrating electrode and an
metallically bonded to each other using the first andair gap. A first semiconductor chip formed with the
second metal spacers. An air gap is formed in a regionfixed electrode is bonded to a second semiconductor
of the condenser microphone located between thechip formed with the vibratingelectrode with the air gap
first semiconductor chip and the secondinterposed between the first semiconductor chip and
semiconductor chip except bonded regions of the firstthe second semiconductor chip. The first
and second metal spacers.semiconductor chip includes the fixed electrode
A method for fabricating a condenser microphone offormed on a first semiconductor substrate, a first
the present invention is a method for fabricating ainterlayer dielectric covering thefixed electrode and the
condenser microphone including a fixed electrode, afirst semiconductor substrate, and a plurality of metal
vibrating electrode and an air gap. A firstspacers formed on the first interlayer dielectric. The
semiconductor chip formed with the fixedelectrode issecond semiconductor chip includes the vibrating
bonded to a second semiconductor chip formed withelectrode formed on a second semiconductor
the vibrating electrode with the air gap interposedsubstrate, a secondinterlayer dielectric covering the
between the first semiconductor chip and the secondvibrating electrode and the second semiconductor
semiconductor chip.substrate, and a plurality of metal spacers formed on
The method includes the steps of: forming the fixedthe second interlayer dielectric. The first semiconductor
electrode on afirst semiconductor substrate, thenchip and the second semiconductor chip are
forming a first interlayer dielectric to cover the fixedmetallicallybonded to each other using the first and
electrode and the first semiconductor substrate andsecond metal spacers. The air gap is formed in a
forming a plurality of metal spacers on the firstregion of the condenser microphone located between
interlayer dielectric, thereby forming thethe first interlayer dielectric and the second interlayer
firstsemiconductor chip; forming the vibrating electrodedielectric except bonded regions of the first
on a second semiconductor substrate, then forming aandsecond metal spacers.
second interlayer dielectric to cover the vibratingWith this structure, the first semiconductor chip formed
electrode and the second semiconductor substratewith the fixed electrode is metallically bonded to the
and forming a plurality of metal spacers on thesecondsecond semiconductor chip formed with the vibrating
interlayer dielectric, thereby forming the secondelectrode using the metal spacers. This enhances the
semiconductor chip; and arranging the first and secondvibration resistance of thecondenser microphone and
semiconductor chips so as to be opposed to eachreduces the parasitic capacitance thereof. In this way,
other and then metallically bonding the first metala small, high-power condenser microphone can be
spacers to the associated second metalspacers. Theachieved with excellent reliability.
air gap is formed in a region of the condenserIn one preferred embodiment, the first semiconductor
microphone located between the first semiconductorchip may further include a detection circuit formed on
chip and the second semiconductor chip exceptthe first semiconductor substrate to detect a signal
bonded regions of the first and second metal spacers.from the condenser microphone.
According to the above-mentioned method, the firstAccording to the condenser microphone of the
semiconductor chip formed with the fixed electrode ispresent invention and the fabrication method for the
metallically bonded to the second semiconductor chipsame, the first semiconductor chip formed with the
formed with the vibrating electrode using the metalfixed electrode is metallically bonded to the second
spacers. Thus, a condensermicrophone with excellentsemiconductor chip formed with the vibratingelectrode
vibration resistance and reduced parasitic capacitanceusing the metal spacers. This enhances the vibration
can be formed. In this way, a small, high-powerresistance of the condenser microphone and reduces
condenser microphone can be achieved with excellentthe parasitic capacitance thereof. In this way, a small,
reliability.high-power condenser microphone can be achieved
In one preferred embodiment, the step of forming thewith excellent reliability.
first semiconductor chip may further include the step