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Image Sensor Story by Yoshiaki Hagiwara
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The most important feature of Image Sensor
is the short wave blue light sensitivity.
The short wave blue light cannot penetrate
more than 0.2 micro meter in depth of silicon crystal.
Usually the photo electron and hole pairs are
generated in the PN junction depletion region
which is deep inside the silicon crystal
of more than a few micro meters in depth.
Hence, the short wave blue light cannot reach
the PN junction depletion region.
Yoshiaki Hagiwara in 1975 proposed
in Japanese Patent Applications
JPA 1975-127646 and JPA 1975-127647
that the surface barrier field induced by
the surface Gaussian impurity atom doping slope
can be used to separate
the photo electron and hole pairs
generated at the silicon surface
of less than 0.2 micro meter in depth.
Yoshiaki Hagiwara in 1978 reported in SSDM1978 paper
the excellent blue light sensitivity
of P+NP double junction type Pinned Photodiode.
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Pinned Photodiode is defined just as a Buried Photodiode
with a pinned surface majority carrier accumulation region
of the fixed and flat surface electrical potential
of no surface electric fileld
with very low surface dark current.
The pinned surface potential also gives
the pinned empty potential
of the pinned buried charge collecting and storage region.
The pinned empty potential well implies
no image lag feature.
Pinned Photodiode is by necessity always Buried Photodiode.
But Buried Photodiode is not always Pinned Photodiode.
Buried Photodiode may have no pinned surface potential.
Buried Photodiode may have
a completely depleted surface potential
with a strong surface electric field
extended to the surface oxide.
The completely depleted surface potential
of Buried Photodiode
means that the floating surface potential
and the floating buried charge collecting and storage region
with the incomplete charge transfer of the image lag problem.
Hence Buried Photodiode may have the image lag problem
while Pinned Photodiode does not have
the image lag problem.
It is not well understood
that Buried Photodiode is not always Pinned Photodiode.
It is not well understood
the difference of Pinned Photodiode and Buried Photodiode.
In either cases, Yoshiaki Hagiwara at Sony invented in 1975
both Buried Photodiode (BPD) ,
Pinned Photodiode(PPD),
and also Hole Accumulation Diode (HAD).
The evidence is given in the Japanese Patent Applicaitons
JPA 1975-127646
JPA 1975-127647
JPA 1975-134985, .
filed by Hagiwara at Sony in 1975.
show that Hagiwara invented Buried Photodiode (BPD),
Pinned Photodiode (PPD)
and Hole Accumulation Diode (HAD).
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
It is also evident in JPA 1975-127646 and JPA 1975-127647
that Hagiwara invented Global Shutter Scheme
of the three level clocking
with MOS Capacitor Buffer Memory.
It is also evident that Hagiwara et al invented
the Electrical Shutter Clocking Scheme
by controlling punch-thru action
of the in-pixel overflow drain (OFD) voltage
as evidenced in JPA 1977-136885.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Hagiwara published recently two IEEE EDS papers.
P2019_3DIC2019Paper_on_3D_Pinned_Photodiode.pdf
P2020_EDTM2020_PaperID_3C4_by_Hagiwara.pdf
MP4_Video_Presentation of EDTM2020_Paper is given below
P2020_EDTM2020_PaperID_3C4_by_Hagiwara.mp4
More details are explained below.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Image Sensor Story by Yoshiaki Hagiwara.pdf
Hagiwara_invented_PPD_and_Sony_HAD_in_1975.html
Hagiwara_invented_PPD_and_Sony_HAD_in_1975.pdf
The_First_Pinned_Photodiode_was_invented_in_1975_by_Yoshiaki_Hagiwar_at_Sony.pdf
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Hagiwara Yoshiaki Lecture Notes for AIPS Robotics
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
AIPS is the non-profit private organizaion (NPPO)
dedicated to produce scientific guide books and educational and introductory materials
devoted for the develpments of the Human Friendly Artificial Intelligent Partner System (AIPS),
AI Real Time Pattern Recognition Processors and Robotics Intelligent Vision Systems.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Yoshiaki Hagiwara was invited to talk about his dreams
in the international technical conferences .
https://imagesensors.org/
P1979_CCD79_in_Edinburgh_1979.pdf
https://www.esscirc-essderc2021.org/
http://www.aiplab.com/P2001_ESSCIRC2001.pdf
http://www.aiplab.com/P2008_ESSCIRC2008Hagiwara.pdf
http://isscc.org/
P2013_ISSCC2013PanelTalk.pdf
https://www.coolchips.org/
P2017_CoolChipsPanel170419.pdf
Yoshiaki Hagiwara also wrote papers about his works and dreams.
P1978_Pinned_Photodiode_1978_Paper_by_Hagiwara.pdf
P1996_Pinned_Photodidoe_used_in_Sony_1980_FT_CCD_Image_Sensor.pdf
P2019_3DIC2019Paper_on_3D_Pinned_Photodiode.pdf
P2020_EDTM2020_PaperID_3C4_by_Hagiwara.pdf
P2020_EDTM_PaperID_3C4_by_Hagiwara_MP4_Video_Presentation
These works were based on the following Japanese Patent Applications
that was never been desiclosed in details until recently
because of Hagiwara himself neglecting to appeal its importance.
JP1975-127646.pdf
JP1975-127647.pdf
JP1975-134985.pdf
JP1977-126885.pdf
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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On Nov 13, 2021, a Japanese Newspaper by Sangyou Times
wrote an aticle introducing Hagiwara.
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https://www.sangyo-times.jp/article.aspx?ID=5331
Future_of_Image_Sensors_and_Solar_Cells.pdf
Future_of_Image_Sensors_and_Solar_Cells.html
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Sony_acknowledged_that_Hagiwara_invented_PPD_with_VOD_for_Electric_Shutter_Function
Semiconductor_History_Museum_of_Japan_also_supoorts_Hagiwara_1975_PPD_invention
Hagiwara_drew_the_Triple_Junction_Type_Pinned_Photodiode_in_his_1975_Lab_Note
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hagiwara-yoshiaki@aiplab.com for my activity at http://www.aiplab.com/
hagiwara@ssis.or.jp for my activity at http://www.ssis.or.jp/en/index.html
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SSIS_Education_Activity ( Members Only )
SSIS_Education_GP_Activity_PR_MP4_01
SSIS_Education_GP_Activity_PR_MP4_02
SSIS_Education_GP_Activity_PR_MP4_03
Image_Sensor_Introduction_MP4_Video_for_AIPS_Robotics_by_Yoshiaki_Hagiwara
Image_Sensor_Story_Hagiwara_html ( Members Only )
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