Fabricating a semiconductor photodetector by annealing to smooth the PN junction
AssigneeHitachi, Ltd.
InventorsKazuhiro Ito, Kazuyuki Nagatsuma, Hiroshi Matsuda, Ichiro Fujiwara
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Abstract
A semiconductor photodetector is disclosed which comprises a pn junction formed in a semiconductor substrate and a pair of electrodes for applying a reverse bias to the pn junction, in which at least a part of the junction plane of the pn junction has been metamorphosed by enhanced diffusion. Hence the pn junction from an outer peripheral portion and a central portion is made smooth.
Claims18
A method of fabricating a semiconductor photodetector comprising the subsequent steps of:
- diffusing impurities into a semiconductor substrate to form a pn junction in said semiconductor substrate;
- depositing a film made of a material different from said semiconductor substrate on a surface region of said semiconductor substrate above at least a central portion of said pn junction of said semiconductor substrate;
- and
- re-diffusing said impurities diffused into said semiconductor substrate in said semiconductor substrate by annealing to make a rugged boundary plane of said pn junction even.
A method of fabricating a semiconductor photodetector comprising the subsequent steps of:
- diffusing impurities from a surface of a semiconductor substrate into said semiconductor substrate to form a pn junction of which depths are different between a central portion and a peripheral portion in said semiconductor substrate;
- depositing a film made of a material different from said semiconductor substrate on at least a surface region of said semiconductor substrate above said central portion;
- and
- annealing said semiconductor substrate.
A method of fabricating a semiconductor photodetector comprising the subsequent steps of:
- diffusing impurities from a surface of a semiconductor substrate into said semiconductor substrate to form a pn junction of which depths are different between a central portion and a peripheral portion;
- depositing a film made of a material different from said semiconductor substrate on at least a surface region of said semiconductor substrate above at least said central portion of said pn junction of said semiconductor substrate;
- and
- re-diffusing said impurities diffused into said semiconductor substrate in said semiconductor substrate by annealing.
A method of fabricating of a semiconductor photodetector comprising the subsequent steps of:
- forming a pn junction in a semiconductor crystal substrate by means of a diffusion method using a different source of impurity, wherein a central portion of said pn junction is formed at a position which is deeper than that of a peripheral portion of said pn junction by 0.2 .mu.m or more;
- and
- depositing a film of a material other than the crystal material of said semiconductor crystal substrate on at least a part of a surface of said semiconductor crystal substrate above said central portion of said pn junction and heating the resultant structure.
A method of fabrication of a semiconductor photodetector comprising the subsequent steps of:
- diffusing into an n type semiconductor substrate a p type impurity by means of a diffusion source thereof through a first window which is formed in an insulating film provided on said n type semiconductor substrate;
- depositing a film of a material other than SiN.sub.x on the resultant structure and forming in said film of the material other than SiN.sub.x a second window the area of which is smaller than that of said first window;
- diffusing into said n type semiconductor substrate a p type impurity by means of a diffusion source thereof through said second window to form a pn junction the depth of which is deeper than that of a pn junction formed through said first window;
- and
- depositing a film of a material other than the crystal material of said n type semiconductor substrate in at least a central portion of said second window and heating the resultant structure.
A method of fabrication of a semiconductor photodetector comprising the subsequent steps of:
- diffusing into an n type semiconductor substrate a p type impurity by means of a diffusion source thereof through a first window which is formed in an insulating film provided on said n type semiconductor substrate;
- enlarging said first window to provide a second window the area of which is larger than that of said first window;
- diffusing into said n type semiconductor substrate a p type impurity by means of a diffusion source thereof through said second window;
- and
- depositing a film of a material other than the crystal material of said n type semiconductor substrate in at least a central portion of said second window and heating the resultant structure.
A method of fabrication of a semiconductor device comprising the subsequent steps of:
- forming a diffused region to form a pn junction in a semiconductor crystal substrate by means of a diffusion method using a diffusion source of impurity;
- depositing a film of a material other than the crystal material of said semiconductor crystal substrate on at least a central portion of the diffused region of a surface of said semiconductor crystal substrate;
- and
- heating the resultant structure without using the diffusion source thereby to make smooth a surface of the pn junction.
Dependencies are inferred from the claim text.