Optical semiconductor device and method for fabricating the same

Abstract

An optical semiconductor device includes: a first conductivity type first semiconductor region; a first conductivity type second semiconductor region formed on the first semiconductor region; a second conductivity type third semiconductor region formed on the second semiconductor region; a photodetector section formed of the second semiconductor region and the third semiconductor region; a micro mirror formed of a trench formed selectively in a region of the first semiconductor region and the second semiconductor region except the photodetector section; and a semiconductor laser element held on the bottom face of the trench. A first conductivity type buried layer of which impurity concentration is higher than those of the first semiconductor region and the second semiconductor region is selectively formed between the first semiconductor region and the second semiconductor region in the photodetector section.

1 . An optical semiconductor device comprising: 
 a first conductivity type first semiconductor region;    a first conductivity type second semiconductor region formed on the first semiconductor region;    a second conductivity type third semiconductor region formed on the second semiconductor region;    a photodetector section formed of the second semiconductor region and the third semiconductor region;    a micro mirror formed of a trench formed selectively in a region of the first semiconductor region and the second semiconductor region except the photodetector section; and    a semiconductor laser element held on a bottom face of the trench,    wherein a first conductivity buried layer of which impurity concentration is higher than those of the first semiconductor region and the second semiconductor region is formed between the first semiconductor region and the second semiconductor region in the photodetector section.    
     
     
         2 . The optical semiconductor device of  claim 1 , wherein 
 the second semiconductor region is formed by epitaxial growth.    
     
     
         3 . The optical semiconductor device of  claim 2 , wherein 
 the third semiconductor region is formed by epitaxial growth.    
     
     
         4 . The optical semiconductor device of  claim 1 , further comprising: 
 a transistor formed in a region of the second semiconductor region and the third semiconductor region except the photodetector section and the trench.    
     
     
         5 . An optical semiconductor device fabrication method, comprising the steps of: 
 forming selectively a first conductivity type buried layer of which impurity concentration is higher than that of a first conductivity type first semiconductor region by ion implantation to a photodetector section formation portion of the first semiconductor region;    forming by epitaxial growth a first conductivity type second semiconductor region of which impurity concentration is lower than that of the buried layer on the first semiconductor region in which the buried layer is formed;    forming a second conductivity type third semiconductor region in the upper part of the second semiconductor region;    forming a photodetector section made of the second semiconductor region and the third semiconductor region in the photodetector section formation portion of the second semiconductor region and the third semiconductor region;    forming, by forming a trench by performing selective anisotropic etching on a region of the first semiconductor region and the second semiconductor region except the photodetector section, a micro mirror formed of a wall face of the trench; and    bonding a semiconductor laser element, which is prepared beforehand in a form of a chip, onto a bottom face of the thus formed trench.    
     
     
         6 . The optical semiconductor device fabrication method of  claim 5 , further comprising the step of: 
 forming selectively a transistor in a region of the second semiconductor region and the third semiconductor region except the photodetector section and the trench.    
     
     
         7 . An optical semiconductor device fabrication method comprising the steps of: 
 forming selectively a first conductivity type buried layer of which impurity concentration is higher than that of a first conductivity type first semiconductor region by ion implantation to a photodetector section formation portion of the first semiconductor region;    forming by epitaxial growth a first conductivity type second semiconductor region of which impurity concentration is lower than that of the buried layer on the first semiconductor region in which the buried layer is formed;    forming a second conductivity type third semiconductor region on the second semiconductor region by epitaxial growth;    forming a photodetector section made of the second semiconductor region and the third semiconductor region in the photodetector section formation portion of the second semiconductor region and the third semiconductor region;    forming, by forming a trench by performing selective anisotropic etching on a region of the first semiconductor region and the second semiconductor region except the photodetector section, a micro mirror formed of a wall face of the trench; and    bonding a semiconductor laser element, which is prepared beforehand in a form of a chip, onto a bottom face of the thus formed trench.    
     
     
         8 . The optical semiconductor device fabrication method of  claim 7 , further comprising the step of: 
 forming selectively a transistor in a region of the second semiconductor region and the third semiconductor region except the photodetector section and the trench.    
     
     
         9 . An optical semiconductor device fabrication method comprising the steps of: 
 forming a first conductivity type second semiconductor region on a first conductivity type first semiconductor region by epitaxial growth;    forming selectively a first conductivity type buried layer of which impurity concentration is higher than that of the first semiconductor region by ion implantation to a boundary portion between the first semiconductor region and the second semiconductor region and a photodetector section formation portion in the vicinity of the boundary portion;    forming a second conductivity type third semiconductor region in an upper part of the second semiconductor region;    forming a photodetector section made of the second semiconductor region and the third semiconductor region in a photodetector section formation portion of the second semiconductor region and the third semiconductor region;    forming, by forming a trench by performing selective anisotropic etching on a region of the first semiconductor region and the second semiconductor region except the photodetector section, a micro mirror formed of a wall face of the trench; and    bonding a semiconductor laser element, which is prepared beforehand in a form of a chip, onto a bottom face of the thus formed trench.    
     
     
         10 . The optical semiconductor device fabrication method of  claim 9 , further comprising the step of: 
 forming selectively a transistor in a region of the second semiconductor region and the third semiconductor region except the photodetector section and the trench.    
     
     
         11 . An optical semiconductor device fabrication method comprising the steps of: 
 forming a first conductivity type second semiconductor region on a first conductivity type first semiconductor region by epitaxial growth;    forming selectively a first conductivity type buried layer of which impurity concentration is higher than that of the first semiconductor region by ion implantation to a boundary portion between the first semiconductor region and the second semiconductor region and a photodetector section formation portion in the vicinity of the boundary portion;    forming a second conductivity type third semiconductor region on the second semiconductor region by epitaxial growth;    forming a photodetector section made of the second semiconductor region and the third semiconductor region in a photodetector section formation portion of the second semiconductor region and the third semiconductor region;    forming, by forming a trench by performing selective anisotropic etching on a region of the first semiconductor region and the second semiconductor region except the photodetector section, a micro mirror formed of a wall face of the trench; and    bonding a semiconductor laser element, which is prepared beforehand in a form of a chip, onto a bottom face of the thus formed trench.    
     
     
         12 . The optical semiconductor device fabrication method of  claim 11 , further comprising the step of: 
 forming selectively a transistor in a region of the second semiconductor region and the third semiconductor region except the photodetector section and the trench.