Semiconductor device and a manufacturing method thereof

Abstract

The performances of a semiconductor device are improved. A semiconductor device has a photodiode and a transfer transistor formed in a pixel region. Further, the semiconductor device has a second transistor formed in a peripheral circuit region. The transfer transistor includes a first gate electrode, and a film part formed of a thick hard mask film formed over the first gate electrode. The second transistor includes a second gate electrode, source/drain regions, silicide layers formed at the upper surface of the second gate electrode, and the upper surfaces of the source/drain regions.

What is claimed is: 
     
         1 . A semiconductor device, comprising:
 a semiconductor substrate;   a first semiconductor region of a first conductivity type formed in a first region on a first main surface side of the semiconductor substrate;   a second semiconductor region formed in a second region on the first main surface side of the semiconductor substrate;   a photodiode formed in the inside of the first semiconductor region;   a transfer transistor formed in the first semiconductor region, and transferring electrical charges generated by the photodiode;   a first transistor formed in the second semiconductor region; and   an interlayer insulation film formed in such a manner as to cover the transfer transistor and the first transistor,   wherein the transfer transistor includes:   a first gate electrode formed over the first semiconductor region via a first gate insulation film; and   a first film part formed of a first insulation film formed over the first gate electrode,   wherein the photodiode includes:   the first semiconductor region; and   a third semiconductor region of a second conductivity type different from the first conductivity type formed in alignment with the first gate electrode in the inside of a first portion of the first semiconductor region arranged on a first side of the first gate electrode,   wherein the first transistor includes:   a second gate electrode formed over the second semiconductor region via a second gate insulation film; and   a fourth semiconductor region being a source region or a drain region formed in the second semiconductor region,   wherein a first metal silicide layer is formed at the upper surface of the second gate electrode, and   wherein a second metal silicide layer is formed at the upper surface of the fourth semiconductor region.   
     
     
         2 . The semiconductor device according to  claim 1 , comprising:
 an amplification transistor formed in the first semiconductor region, and amplifying a signal according to electrical charges transferred by the transfer transistor;   a selection transistor formed in the first semiconductor region, and selecting the amplification transistor; and   a reset transistor formed in the first semiconductor region, and erasing the electrical charges in the photodiode,   wherein the amplification transistor includes:   a third gate electrode formed over the first semiconductor region via a third gate insulation film;   a fifth semiconductor region being a source region or a drain region formed in the first semiconductor region; and   a second film part formed of a second insulation film formed over the third gate electrode,   wherein the selection transistor includes:   a fourth gate electrode formed over the first semiconductor region via a fourth gate insulation film;   a sixth semiconductor region being a source region or a drain region formed in the first semiconductor region; and   a third film part formed of a third insulation film formed over the fourth gate electrode,   wherein the reset transistor includes:   a fifth gate electrode formed over the first semiconductor region via a fifth gate insulation film;   a seventh semiconductor region being a source region or a drain region formed in the first semiconductor region; and   a fourth film part formed of a fourth insulation film formed over the fifth gate electrode,   wherein the interlayer insulation film is formed in such a manner as to cover the amplification transistor, the selection transistor, and the reset transistor,   wherein a third metal silicide layer is formed at the upper surface of the fifth semiconductor region,   wherein a fourth metal silicide layer is formed at the upper surface of the sixth semiconductor region, and   wherein a fifth metal silicide layer is formed at the upper surface of the seventh semiconductor region.   
     
     
         3 . The semiconductor device according to  claim 1 , comprising:
 an amplification transistor formed in the first semiconductor region, and amplifying a signal according to electrical charges transferred by the transfer transistor;   a selection transistor formed in the first semiconductor region, and selecting the amplification transistor; and   a reset transistor formed in the first semiconductor region, and erasing electrical charges in the photodiode,   wherein the amplification transistor includes:   a third gate electrode formed over the first semiconductor region via a third gate insulation film; and   a fifth semiconductor region being a source region or a drain region formed in the first semiconductor region,   wherein the selection transistor includes:   a fourth gate electrode formed over the first semiconductor region via a fourth gate insulation film; and   a sixth semiconductor region being a source region or a drain region formed in the first semiconductor region,   wherein the reset transistor includes:   a fifth gate electrode formed over the first semiconductor region via a fifth gate insulation film; and   a seventh semiconductor region being a source region or a drain region formed in the first semiconductor region,   wherein the interlayer insulation film is formed in such a manner as to cover the amplification transistor, the selection transistor, and the reset transistor,   wherein a third metal silicide layer is formed at the upper surface of the third gate electrode,   wherein a fourth metal silicide layer is formed at the upper surface of the fifth semiconductor region,   wherein a fifth metal silicide layer is formed at the upper surface of the fourth gate electrode,   wherein a sixth metal silicide layer is formed at the upper surface of the sixth semiconductor region,   wherein a seventh metal silicide layer is formed at the upper surface of the fifth gate electrode, and   wherein an eighth metal silicide layer is formed at the upper surface of the seventh semiconductor region.   
     
     
         4 . The semiconductor device according to  claim 1 , comprising:
 a plurality of pixels formed in an array at the first main surface of the semiconductor substrate in the first region,   wherein each of the pixels includes:   the photodiode; and   the transfer transistor, and   wherein the second semiconductor region is formed in the second region being a peripheral region of the first region.   
     
     
         5 . The semiconductor device according to  claim 1 ,
 wherein the first film part includes:   a fifth film part formed of the first insulation film; and   a first sidewall part formed of a fifth insulation film formed at the side surface of the fifth film part, and   wherein the film thickness of the first insulation film is larger than the film thickness of the fifth insulation film.   
     
     
         6 . The semiconductor device according to  claim 1 ,
 wherein the distance from the first main surface of the semiconductor substrate to the surface of the third semiconductor region opposite to the first main surface side thereof is larger than the film thickness of the first gate electrode.   
     
     
         7 . The semiconductor device according to  claim 1 ,
 wherein the transfer transistor includes an eighth semiconductor region being a drain region formed at a second portion of the first semiconductor region arranged on a second side of the first gate electrode opposite to the first side thereof.   
     
     
         8 . The semiconductor device according to  claim 1 ,
 wherein the first insulation film is formed of a silicon oxide film, a silicon nitride film, or a silicon oxynitride film.   
     
     
         9 . A method for manufacturing a semiconductor device, comprising the steps of:
 (a) providing a semiconductor substrate;   (b) forming a first semiconductor region of a first conductivity type in a first region on a first main surface side of the semiconductor substrate;   (c) forming a second semiconductor region in a second region on the first main surface side of the semiconductor substrate;   (d) forming a first conductive film over the first semiconductor region, and over the second semiconductor region via a first gate insulation film;   (e) forming a first film part formed of a first insulation film over a portion of the first conductive film formed over the first semiconductor region, and forming a second film part formed of a second insulation film over a portion of the first conductive film formed over the second semiconductor region;   (f) after the step (e), etching the first conductive film, thereby leaving a portion of the first conductive film covered with the first film part, and forming a first gate electrode, and leaving a portion of the first conductive film covered with the second film part, and forming a second gate electrode;   (g) forming a third semiconductor region of a second conductivity type different from the first conductivity type in the inside of a first portion of the first semiconductor region arranged on a first side of the first gate electrode, in alignment with the first gate electrode by an ion implantation method, and thereby forming a photodiode including the first semiconductor region and the third semiconductor region;   (h) after the step (g), removing the second film part;   (i) forming a fourth semiconductor region being a drain region at a second portion of the first semiconductor region arranged on a second side of the first gate electrode opposite to the first side thereof, and thereby forming a transfer transistor including the first gate electrode, the fourth semiconductor region, and the first film part, and transferring electrical charges formed by the photodiode;   (j) after the step (h), forming a fifth semiconductor region being a source region or a drain region in the second semiconductor region, and thereby forming a first transistor including the second gate electrode and the fifth semiconductor region;   (k) forming a first metal silicide layer at the upper surface of the second gate electrode, and forming a second metal silicide layer at the upper surface of the fifth semiconductor region; and   (l) after the step (k), forming an interlayer insulation film in such a manner as to cover the transfer transistor and the first transistor,   wherein the film thickness of the first insulation film is larger than the film thickness of the second insulation film.   
     
     
         10 . The method for manufacturing a semiconductor device according to  claim 9 ,
 wherein in the step (e), over portions of the first conductive film formed over the first semiconductor region, a third film part, a fourth film part, and a fifth film part are forme each formed of the first insulation film, respectively, and   wherein in the step (f), by etching the first conductive film, a portion of the first conductive film covered with the third film part is left, thereby to form a third gate electrode, a portion of the first conductive film covered with the fourth film part is left, thereby to form a fourth gate electrode, and a portion of the first conductive film covered with the fifth film part is left, thereby to form a fifth gate electrode,   the method for manufacturing a semiconductor device, further comprising the steps of:   (m) forming a sixth semiconductor region being a source region or a drain region in the first semiconductor region, and thereby forming an amplification transistor including the third gate electrode, the sixth semiconductor region, and the third film part, and amplifying a signal according to electrical charges transferred by the transfer transistor;   (n) forming a seventh semiconductor region being a source region or a drain region in the first semiconductor region, and thereby forming a selection transistor including the fourth gate electrode, the seventh semiconductor region, and the fourth film part, and selecting the amplification transistor;   (o) forming an eighth semiconductor region being a source region or a drain region in the first semiconductor region, and thereby forming a reset transistor including the fifth gate electrode, the eighth semiconductor region, and the fifth film part, and erasing electrical charges in the photodiode;   (p) forming a third metal silicide layer at the upper surface of the sixth semiconductor region;   (q) forming a fourth metal silicide layer at the upper surface of the seventh semiconductor region; and   (r) forming a fifth metal silicide layer at the upper surface of the eighth semiconductor region,   wherein in the step (l), the interlayer insulation film is formed in such a manner as to cover the amplification transistor, the selection transistor, and the reset transistor.   
     
     
         11 . The method for manufacturing a semiconductor device according to  claim 9 ,
 wherein, in the step (e), over portions of the first conductive film formed over the first semiconductor region, a third film part, a fourth film part and a fifth film part are formed each formed of the first insulation film, respectively,   wherein in the step (f), by etching the first conductive film, a portion of the first conductive film covered with the third film part is left, thereby to form a third gate electrode, a portion of the first conductive film covered with the fourth film part is left, thereby to forma fourth gate electrode, and a portion of the first conductive film covered with the fifth film part is left, thereby to form a fifth gate electrode, and   wherein in the step (h), the third film part, the fourth film part, and the fifth film part are removed,   the method for manufacturing a semiconductor device, further comprising the steps of:   (m) after the step (h), forming a sixth semiconductor region being a source region or a drain region in the first semiconductor region, and thereby forming an amplification transistor including the third gate electrode and the sixth semiconductor region, and amplifying a signal according to electrical charges transferred by the transfer transistor;   (n) after the step (h), forming a seventh semiconductor region being a source region or a drain region in the first semiconductor region, and thereby forming a selection transistor including the fourth gate electrode and the seventh semiconductor region, and selecting the amplification transistor;   (o) after the step (h), forming an eighth semiconductor region being a source region or a drain region in the first semiconductor region, and thereby forming a reset transistor including the fifth gate electrode and the eighth semiconductor region, and erasing the electrical charges in the photodiode;   (p) forming a third metal silicide layer at the upper surface of the third gate electrode, and forming a fourth metal silicide layer at the upper surface of the sixth semiconductor region;   (q) forming a fifth metal silicide layer at the upper surface of the fourth gate electrode, and forming a sixth metal silicide layer at the upper surface of the seventh semiconductor region; and   (r) forming a seventh metal silicide layer at the upper surface of the fifth gate electrode, and forming an eighth metal silicide layer at the upper surface of the eighth semiconductor region,   wherein in the step (l), the interlayer insulation film is formed in such a manner as to cover the amplification transistor, the selection transistor, and the reset transistor.   
     
     
         12 . The method for manufacturing a semiconductor device according to  claim 9 ,
 wherein the step (e) comprises the steps of:   (e1) forming the first insulation film over the first conductive film;   (e2) patterning the first insulation film, and thereby forming a sixth film part formed of the first insulation film over a portion of the first conductive film formed over the first semiconductor region, and removing the first insulation film over a portion of the first conductive film formed over the second semiconductor region;   (e3) forming the second insulation film over the first conductive film including over the sixth film part;   (e4) etching the second insulation film in the first region, thereby leaving the second insulation film at the side surface of the sixth film part, and forming a first sidewall part, and forming the first film part including the sixth film part and the first sidewall part; and   (e5) patterning the second insulation film in the second region, and thereby forming the second film part formed of the second insulation film over a portion of the first conductive film formed over the second semiconductor region.   
     
     
         13 . The method for manufacturing a semiconductor device according to  claim 9 ,
 wherein the step (g) comprises the steps of:   (g1) forming a resist film over the semiconductor substrate including over the first film part and over the second film part;   (g2) forming a first opening penetrating through the resist film, and reaching the first portion of the first semiconductor region; and   (g3) forming the third semiconductor region in the inside of the first portion exposed at the bottom of the first opening in alignment with the first gate electrode by an ion implantation method, and thereby forming the photodiode including the first semiconductor region and the third semiconductor region,   wherein in the first opening formed in the step (g2), the upper surface of a portion of the first film part formed over the end on the first side of the first gate electrode is exposed.   
     
     
         14 . The method for manufacturing a semiconductor device according to  claim 9 ,
 wherein in the step (g), the third semiconductor region is formed such that the distance from the first main surface of the semiconductor substrate to the surface of the third semiconductor region opposite to the first main surface side thereof is larger than the film thickness of the first gate electrode.   
     
     
         15 . The method for manufacturing a semiconductor device according to  claim 9 ,
 wherein the first insulation film is formed of a silicon oxide film, a silicon nitride film, or a silicon oxynitride film.