Technique using boron effectively protects metal-oxide semiconductor devices from ionizing radiation without using shielding materials. Boron is introduced into insulating gate oxide layer at semiconductor-insulator interface

Danchenko, V.

English

NASA Technical Reports Server

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April 1974	 B74-10026 
NASA TECH BRIEF 
Goddard Space Flight Center
	
/	
A 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Radiation Hardening of Metal-Oxide Semiconductor (MOS) 
Devices by Boron 
.
The problem: 
Ionizing radiation frequently alters the operational 
characteristics of MOS devices. One common radiation 
damage in MOS devices involves shifted gate threshold 
potentials, which renders the devices unstable and often 
inoperative. The present methods of protection from 
this radiation, using shielded enclosures, have not been 
effective. Shielding material adds substantial weight to 
the circuits and, if poorly designed, transmits much 
radiation.
The solution: 
A radiation-hardening technique using boron effec-
tively protects MOS devices from ionizing radiation 
without the use of shielding materials. 
How it's done: 
In this technique, boron, or another element with 
acceptor properties, is introduced into the insulating 
gate oxide layer at the semiconductor-insulator interface 
(see Figure 1). Boron concentration within the layer is 
approximately 1018 atoms/cm 3 , the gate oxide being 
10.0 to 30.0 rim in thickness. 
Irradiation 
(including Boron) 
S Figure 1. MOS Device
(continued overleaf) 
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https://ntrs.nasa.gov/search.jsp?R=19740000026 2020-03-17T14:01:32+00:00Z
. Normal	 P-Channel (Boron)	 N-Channel (Boron) 
- 
0 
Al	 - / / 
- —A2 / 
/ 
-63
	
/	 N-Channel 
o	 / 
-
	
Untreated 
CL
/	 - - - - 
- - 
•	 —A	 /	 - /	 - - - - - 
/ - - - - - - - - - 
—A
P-Channel 
'	 —A7	 Untreated 
—A8 
—Ag
1	 10	 100	 1000
Time After Irradiation - Hours 
Figure 2. Gate Threshold Potential of P-Channel and N-Channel 
MOS Devices as a Function of Time After Irradiation 
The resulting improvements in MOS performance are 
shown in Figure 2: the devices have been irradiated with 
10 13
 electrons/cm2 at 1.5 MeV. The two upper curves 
shown are the improved recovery times for a p-channel 
and n-channel MOS containing boron. The two bottom 
curves are for the untreated p-channel and n-channel 
MOS showing recovery after irradiation. In this case, 
boron-treated, p-channel and n-channel recovery times 
are approximately 3 and 8 hours, respectively. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Goddard Space Flight Center 
Code 207.1 
Greenbelt, Maryland 20771 
Reference: TSP74-10026
Patent status: 
This invention is owned by NASA, and a patent 
application has been filed. Inquiries concerning non-
exclusive or exclusive license for its commercial develop-
ment should be addressed to: 
Patent Counsel 
Goddard Space Flight Center 
Code 204 
Greenbelt, Maryland 20771 
Source: Vitaly Danchenko 
Goddard Space Flight Center 
(GSC-1 1425) 
B74-10026
	 Category 01,03


Radiation hardening of metal-oxide semi-conductor (MOS) devices by boron

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