Hagiwara invented Pinned Photodiode in 1975

http://www.aiplab.com/Hagiwara_invented_PPD_and_Sony_HAD_in_1975.pdf






The Evidence is clealy given above by Figure 7 of
Hagiwara 1975-127647 Japanese Patent Applciation
on the N+NP+N junction type dynamic photo transistor
with the Golbl Shutter Function, which is essential and
needed by necessity to achieve the global shutter
functionfor themodern CMOS image sensors.

The Evidence is clealy given below also by Figure 6 of
Hagiwara 1975-134985 Japanese Patent Applciation
on the P+NPNsub junction type dynamic photo thrystor
with the punch thru vertical overflow drain (VOD) function
and the image lag free feature which is essential and
needed by necessity to achieve the electrical shutter
function for the fast action pictures.





Pinned Photodiode is defined as the P+NP junction type
dynamic photo transistor structure with the surface P+ layer
pinned and fixed by the adjacent P+ channel stop region or the
nearby metal contact. Pinned Photodiode has the buried charge
storage N region with the minimum value of the empty N region
potential well also being pinned and fixed by the P+ and P region
fixed voltages at the both sides of the buried signal charge
collecting N region.


The following slide shows Type (0) of the conventional N+P junction
photodiode with the poor blue light sensitivity and the serious image
lag problems,Type(1) of the P+PN+Psub junction type Pinned Photodiode
developped and reported at SSDM1978 by Hagiwara at Sony and
Type(2,3) of the MOS photo capacitor developped by Sony team with
the thin polysilicon electrode to achieve a fairly good blue light sensitivity.

Type(1) and Type(2,3) have the complete charge transfer operation mode
with the completely image free feature and can perform the electrical
shutter function.

The electrical shutter function needs by necessity the photodiode
with the complete charge transfer capability to achieve the completely
image free feature.

Type(0) of the N+P junction with the floating surface N+ storage has
the serious image lag problem and cannot perform the electrical shutter.




See the type (1) of the P+PN+Psub junction type Pinned Photodiode
originally developped in 1978 by Hagiwara at Sony and reported
at the SSDM1978 conference in Tokyo, Japan with the very high blue
light sensitivity, the completely image lag free freature and the very
low surface dark current because of the Pinned Surface P+ Hole
Accumulation Device (HAD) .


See SSDM1978 Conference Paper in 1978 at Tokyo , Japan.

http://www.aiplab.com/P1978_Pinned_Photodiode_1978_Paper_by_Hagiwara.pdf




The original type (0) of the floating surface N+P junction type photodiode
has the poor image lag feature and also fairly poor blue light sensitivity
because the photo electron and hole pairs created at the silicon surface
will be quickly recombined. There is no electric field at the silicon surface,
where the signal electrons are accumulated and the electron sea level is
flat with no electric field at the silicon surface.




Remember ? The blue short wave light cannot penetrate the silicon crystal
more than 0.2 micro meter in the silicon crystal depth.


Besides, we can no way form a PN junction depletion region within the
0.2 micro meter in the silicon crystal depth.

We need to have a new and unique way of separating the photo electron
and hole pairs created at the very near silicon surface.

The silicon surface P+P doping slope can induce the barrier electric field
to separate the photo electron and hole pairs created at the silicon surface.

Hagiwara proposed the N+NP+NPN junction type Pinned Photodiode
in his Japanese Patent Applications JPA 1975-127646 and also the
the N+NP+NP junction type Pinned Photodiode in his Japanese Patent
Applications JPA 1975-127647.

See the Fig. 7 of Hagiwara 1975 patent applications, where the silicon surface
is pinned and has the N+N doping profile to achieve the excellent short wave
blue lihgt sensitivity with the Buried P+ signal charge storagae region with
the complete charge transfer capability to achieve the image lag free feature.



Hagiwara proposed to use the P+P doping slope of the Gaussian ion plantation
technique to create the surface P+P doping induced barrier electric field
to separate the photo electron and hole pairs created at the silicon surface.


http://www.aiplab.com/P1978_Pinned_Photodiode_1978_Paper_by_Hagiwara.pdf

http://www.aiplab.com/P1996_Pinned_Photodidoe_used_in_Sony_1980_FT_CCD_Image_Sensor.pdf





Electrical Shutter function can be realized
both by the type (1) of Pinned Photodiode
and the type (2,3) of the MOS photo capacitor
since the both structures have the image lag
free features with the complete charge transfer
capability. However, the type (0) of the floating
surface N+ P junction has the serious image
lag feature and canot function as the electrical
shutter since the signal charge cannot be
depleted completely from this surface floating
N+ P junction type photodiode.





There were three types of the vertical overflow drain structures.


The second type (2) has the MOS capacitor with the metal electrode and
has the poor light seisitivity since the metal gate reflects the incident light.

Besides the signal charge is at the silicon oxide and silicon crystal surface
in case of the second type(2), the surface P region with a relatively wide
width must be completely depleted with a very, very high overflow drain
(VOD) voltage which is almost impossible to achieve.

In case of the type (3) of the P+NPNsub junction type Pinned Photodiode
proposed in 1975 by Hagiwara at Sony, the vertical overflow drain (VOD)
function can be easily realized with a fairly reasonable VOD voltage.

Sony developped in 1987 the ILT CCD image sensor with this electrical
shutter function for the first time in the world using the Hagiwara 1975
invention of the P+NPNsub junction type Pinned Photodiode with the
vertical overflow drain (VOD) function and the completely image lag
free features which is by neccesity needed and is essential to achieve
the electron shutter function for the fast motion and action pictures.

Hagiwara 1975 inventions ( JPA 1975-127646, 1975-127647 and
1975-134985 ) and 1977 invention (JPA 1977-126885 ) initiated
the development of the modern intelligent image sensor with
the completely film-less and mechanical-free features for the
AI IoT Robotics World.
.



Pinned Photodiode must have the following important features.

(1) The complete signal charge transfer capability to achieve
the completely image lag free feature , needed by necessity
together with the VOD function, to realize the mechanically
free electrical shutter funtion for the fast action pictures.


(2) The very low surface dark current since there is no surface
electric electric field and the surface is quenched by the P+
surface hole accumulation layer.


(3) The very excellent short wave blue light seisitivity is achieved
by the surface P+ doping profile, an effectively Gaussian P+P
doping profile formed by the surface ion implantion technology.


The short wave blue light cannot penetrate more
than 0.2 micro meter into the silicon crystal.

It is impossible to form a PN junction
depletion region at such a nearby surface.

So we must need another physical principle.

The surface impurity P+P doping prifile induces the P+P barrier
electric field and the barrier potential drop kT ln ( P+/P ) at the
silicon surface , achieving the photo electron and hole separations
at the silicon surface within the surface depth of 0.2 micoro meter
into the silicon crystal. In this special way, the very excellent short
wave blue light sensitivity is achieved, which was not widely known.


This is why the SONY Hole Accumulatio Diode (HAD) which is the
Pinned Photodiode with the VOD function has the very excellent
short wave blue light seisitivity. This is why the CCD and CMOS
image sensorsa are truely very light sensitive.

See the Fig.6 of the Japanese patent application JPA 1975-134985 as shown below.





The first Pinned Photodiode was invented in 1975
in the form of N+N-P+NP-P junction type
buried photo thyristor with the punch thru charge
transfer mode as shown in Fig. 7 of the Japanese
patent application JPA 1975-127646 , filed on
Oct 23, 1975 by Hagiwara at Sony.

Hagiwara also invented , on the same date on Oct 23, 1975,
the N+NP+N junction type dynamic photo transistor , w
hich has the buried P+ photo siginal charge collecting
storage region , and with the N+N surface pinned and
fixed by the exteranal voltage in order to achieve
the complete signal charge transfer operation mode
to the front surface MOS capacitor storage
memory for the Global Shutter operation which is
essential for the modern back light illumination
CMOS image sensor applications.

See the Fig.7 of Japanese patent application JPA 1975-127647 .

.




The P+P surface pinned and fixed voltage by the exteranal voltage achieves
the complete signal charge transfer operation mode to the front surface MOS
capacitor storage memory which is needed and essential for the Global Shutter
operation for the modern back light illumination CMOS image sensor applications.





The detailes were explained in the following two IEEE conference papers.

(1) IEEE International 3D Systems Integration Conference (3DIC2019)

"Multichip CMOS Image Sensor Structure for Flash Image Acquisition"
IEEE International 3D Systems Integration Conference 2019 (3DIC2019)
Digest of Technical Papers, Sendai, Japan, Paper4017, October 2019

http://www.aiplab.com/P2019_3DIC2019Paper_on_3D_Pinned_Photodiode.pdf


(2) Single Author Paper at Manufacturing Technology Conference (EDTM2020)

"Simulation and Device Characterization of the P+PN+P Junction Type
Pinned Photodiode and Schottky Barrier Photodiode"
IEEE Electron Device, Manufacturing Technology Conference (EDTM2020),
Digest of Technical Papers, Penang Malaysia, Paper ID 3D6, March 2020

http://www.aiplab.com/P2020_EDTM2020_PaperID_3C4_by_Hagiwara.pdf


Hagiwara developped Pinned Photodiode in 1975

The detailes were explained in the following
international conference and technical papers.


(1) SSDM1978 Conference Paper in 1978 at Tokyo , Japan.

http://www.aiplab.com/P1978_Pinned_Photodiode_1978_Paper_by_Hagiwara.pdf

(2) CCD1979 Conference invited Paper in September 1979 at Edinburgh , Scotland, UK

"ADVANCES in CCD Imager " Technical Digest of IEEE
International Conference of CCD Image Sensors (IEEE CCD'79),
Edinburgh, Scotland UK, September 1979

https://www.imagesensors.org/Past%20Workshops/1979%20CCD79/03-1%20Hagiwara.pdf


(3)Single Author, Invited Paper at IEEE Electrochemical Society ECS 1980 conference

"A CCD color imager with narrow-channel transfer gates", Proceeding of
the 157th Electrochemical Society Meeting, May 11-16, 1980, St. Luis, USA

(4) IEEE EDS Electron Device Journal Paper in Dec1996

"High Density and High Quality Frame Transfer CCD Imager with
Very Low Smear, Low Dark Current and Very High Blue Sensitivity",
IEEE Transaction on Electron Devices, Vol 43, no. 12, December 1996

http://www.aiplab.com/P1996_Pinned_Photodidoe_used_in_Sony_1980_FT_CCD_Image_Sensor.pdf

(5) Single Author, Invited Talk at ESSCIRC2001, Villach, Austria,

"Micro-Electronics for Home Entertainment" Technical Digest of IEEE
ESSCIRC International Conference (ESSCIRC2001), Villach, Austria,
September, 2001

http://www.aiplab.com/P2001_ESSCIRC2001.pdf


(6)Single Author, Invited Talk at ESSCIRC2008, at Edinburgh, Scotland UK

"SOI Design in Cell Processor and Beyond", Technical Digest of
IEEE ESSCIRC International Conference (ESSCIRC2008),
Edinburgh, Scotland UK, September 2008

http://www.aiplab.com/P2008_ESSCIRC2008Hagiwara.pdf


(7) Single Author, Invited Plenary Panel Talk at ISSCC2013 Conferenc

"The p-n-p-n Diode in Future Linear Motor Cars and in Modern Images"
IEEE Solid State Circuit Society ISSCC2013 Conference, February 2013.

http://www.aiplab.com/P2013_ISSCC2013PanelTalk.pdf



Sony recognized Hagiwara as the inventor of Pinned Photodiode.



https://www.sony.net/SonyInfo/News/notice/20200626/






https://www.sony.co.jp/SonyInfo/News/notice/20200626/




Japan History Museum recognized Hagiwara as the inventor of Pinned Photodiode.



https://www.shmj.or.jp/english/pdf/dis/exhibi1005E.pdf





https://www.shmj.or.jp/museum2010/exhibi1005.html






A Web Site writer also recognized Hagiwara as the inventor of Pinned Photodiode.

https://electronics.stackexchange.com/questions/83018/difference-between-buried-photodiode-and-pinned-photodiode








































Hagiwara walked a long, long way for 32 years from 1975 till 2007
to get the victory over the Fairchild, NEC and KODAK Patent Wars.

Hagiwara joined Sony in 1975 and soon filed three basic patents
on the Pinned Photodiode and finally retired from Sony at age 60
in 2008, the next year after, the Patent War finally ended in 2007.

His whole engineering life was a struggle for the image sensor IPs.

But Hagiwara was and still is very happy about his 1975 inventions.



























Hagiwara invented Pinned Photodiode in 1975



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