CA1200622A - Collector for radiation-generated current carriers in a semiconductor structure - Google Patents

Collector for radiation-generated current carriers in a semiconductor structure

Info

Publication number
CA1200622A
CA1200622A CA000415567A CA415567A CA1200622A CA 1200622 A CA1200622 A CA 1200622A CA 000415567 A CA000415567 A CA 000415567A CA 415567 A CA415567 A CA 415567A CA 1200622 A CA1200622 A CA 1200622A
Authority
CA
Canada
Prior art keywords
major surface
epitaxial layer
grid layer
layer
semiconductor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000415567A
Other languages
French (fr)
Inventor
Howard C. Kirsch
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AT&T Corp
Original Assignee
Western Electric Co Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Western Electric Co Inc filed Critical Western Electric Co Inc
Application granted granted Critical
Publication of CA1200622A publication Critical patent/CA1200622A/en
Expired legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/71Manufacture of specific parts of devices defined in group H01L21/70
    • H01L21/74Making of localized buried regions, e.g. buried collector layers, internal connections substrate contacts
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00Details of semiconductor or other solid state devices
    • H01L23/552Protection against radiation, e.g. light or electromagnetic waves
    • H01L23/556Protection against radiation, e.g. light or electromagnetic waves against alpha rays
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001Technical content checked by a classifier
    • H01L2924/0002Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Electromagnetism (AREA)
  • Toxicology (AREA)
  • Manufacturing & Machinery (AREA)
  • Semiconductor Memories (AREA)

Abstract

COLLECTOR FOR RADIATION-GENERATED CURRENT
CARRIERS IN A SEMICONDUCTOR STRUCTURE

Abstract An n+ type buried grid layer at the interface of a p+ type semiconductor substrate and a p type epitaxial layer serves to absorb alpha particle induced charge and other stray charge in the epitaxial layer and substrate.
The grid layer is spaced sufficiently from a major surface of the epitaxial layer so as not to have any significant adverse affect on circuits and/or devices fabricated on the major surface. Circuits and/or devices fabricated on the major surface of the epitaxial layer are thus at least partly protected against loss of information due to alpha particle hits and other stray leakage generators. When no epitaxial layer is used, the buried grid is formed below the major surface of the substrate into which circuits and/or device are fabricated.

Description

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This invention relates to a semiconductor structure comprisinq a semiconductor body having a bulk portion which is of a first conductivity type and having a major surface which is adapted to have electronic devices fabricated thereon.
Many of today's high density MOS random access memories (RAMS) are suhject to alpha par-ticle induced "soft" errors. U.S. Patent No. 4,112,575 describes a MOS
switched-capacitor memory cell which uses a capacitor structure that has relatively high capacitance per unit area and is resistant to alpha particle caused loss of charge (stored memory information). Other parts oE the memory cell, such as the n-~ type drain/source bit line, are essentially unprotected from alpha particle hits and thereEore such hits may cause information errors.
Some have proposed the use of an alpha particle absorbinc~ coating on top of a finished integrated circuit chip as a way of protecting against "soft" errors. These coatings may crack or may cause the integrated circuit chip to crack or to have a bonding wire pulled off. This could result in "soft" errors or a complete failure of the chip.
In accordance with the invention these problems are overcome in a semiconductor structure characterized by means for collecting radiation-generated current carriers 2r~ in the semiconductor body comprising a grid layer located within the semiconductor body at a location which is rem~ved ~rom the major surface; the semiconductor body portions on opposite sides of the grid layer beincJ in mutual electrical contact, and the distance between the 3() ~rid lflyer and the major surface is suE~icient such that the qrid layer has no significant electrical effect on any electronic devices located on the major surface.
In the drawing~
The FIGURE illustrates an embodiment of the present invention.

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The present invention is directed to a semiconductor structure comprising a semiconductor body having a bulk portion of a first conductivity type and a major surface which is adapted to have circuits and/or devices fabricated thereon. A grid layer of the opposite conductivity type is located within the semiconductor body at such distance below the major surface such that it causes essentially no significant adverse affects on the operations of circuits and/or devices formed on the major surface. The openings in the grid layer are designed to have sufficient dimensions such that the portions oE the semiconductor body on each side of the grid layer are essentially always in electrical contact with each other.
The grid layer, which may have a contact region connecting same to the major surface, serves to absorb alpha particle induced charge and other s~ray charge in the semiconductor body. This serves to help protect against losses of information that may be stored or transferred between circuits and/or devices fabricated on the major surface.
rhe semiconductor body may comprise just a semiconductor substrate or it may comprise an epitaxial layer on top of a semiconductor substrate. In the latter case, the grid layer is typically positioned between the epitaxial layer and the substrate~ I-t can, however, be positioned wholly w;thin the epitaxial layer.
Referring now to the FI~URE, there is illustrated a prospective partly cutaway view of a portion o a semiconductor str~lcture 10 in accordance with the present inventioll. Structure 10 comprises a semiconductor ~) s~lbstrate 12 of a first conductivity type, an epitaxial layer 1~ o the first conductivity type but of lower impurity concentration, and a grid layer 16 which is of a second conductivity type that is opposite the first and which is sandwiched between substrate 12 and epitaxial layer 14. Portions of substrate 12 extend through openings in grid layer 16 and contact bottom portions of epitaxial layer 14.

~2~)6~Z

Epitaxial layer 14 has a major surface 18 into which circuits and/or devices can be fabricated. For example, a 64,000 bit MOS RAM using dynamic switched-capacitor memory cells could be fabricated in epitaxial layer 14 with major surface 18 serving as the major surface of the memory. This type of memory is potentially sensitive to alpha particles which can strike the memory and cause an error in information stored in a memory cell or information being transferred within the mernory. Grid layer 16 is designed and located within structure 10 so as to collect (absorb) stray charge, including alpha particle induced charge, without significantly adversely affecting the operation of circuits and/or devices fabricated on (into) major surface 18 of epitaxial layer 14.
For illustrative purposes substrate 12, epitaxial layer 14, and grid layer 16 are assumed to be of p~, _, and n+ type conductivity, respectively. Typically, p+ type substrate 12 is biased at the most negative potential used with structure 10 so as to reverse bias p-n junctions and to help stabilize the threshold voltages of MOS transistors ~abricated on major surface 18. Substrate 12 could be biased through a _~ type region (not illustrated) which extencls Çrom substrate 12 through epitaxial layer 1~ and ~5 intersects major surface 18 where the most negative po~enticll source used with structure ln is connected. The use of a dlscrete negative potential generator circuit (not illustrated), or one (not illustrated) fabricated on surface lR, allows the substrate 12 to be at a negative potential independent of the most negative potential usecl with structure 10.
The dimensions of the openings in grid layer 16 are selected such that depletion regions spreading out from grid layer 16 into epitaxial layer 14 and/or substrate 12 do not pinch off electrical contact between epitaxial layer 14 and substrate 12. The distance between -the bottoms of circuits and/or devices that are fabricated into surface 18 of layer 14 and grid layer 16 is selected such that grid layer 15 has essentially no significant adverse electrical affect on the operation of the circuits and/or devices.
Grid layer 16 can be allowed to electrically float in potential. Alternatively, a deep n~ type region can be formed through epitaxial layer 14 to make contact to grid layer 16 to allow grid layer 16 to be reve~se biased with respect to epitaxial layer 14 and semiconductor substrate 12 by the application of an appropriate potential to the n+ type region.
If grid layer 16 is allowed to electrically float in potential it tends to be close to a potential which forward biases the p-n junctions which comprise p type epitaxial layer 14 and _+ type substrate 12 and n+ type grid layer 16 because of the collection (absorption) of electrons fro~ leakage sources in substrate 12 and epitaxial layer 14. If an alpha particle hits epitaxial layer 14 then the generated electrons in layer 14 diffuse through layer 14, are attracted into the depletion region formed near the junction of layer 14 and grid layer 16, and are then swept into grid layer 16~ This tends to further forward bias the p-n junction comprising layers 14 ancl 16 and thus causes injection of electrons back into layer 14.
7.5 This re-injection has a drift field in grid layer 16 to aicl in spreading out laterally and therefore spreads out the excess electrons faster than is the case if grid layer 16 does no~ exist anc] the alpha particle c3enerated electrons just diffuse normally through epitaxial layer 14. An electrically Eloating grid region 16 thus has the net affect of spreading out the electrons created by an alpha particle hit over a wider area of epitaxial layer 14 such that the detrimental affects on any one circuit and/or device is reduced over what is the case if grid layer 16 is not used.
If grid layer 16 is positively biased with respect to substrate 12, then alpha particle generated electrons and other stray charge in epitaxial layer 14 or substrate 12 are collected into grid layer 16 and there is essentially no re-injection back into epitaxial layer 14 or substrate 12.
If grid layer 16 is held at essentially the same potential of substrate 12, it will still collect (absorb) a relatively large number of alpha particle induced electrons or stray charge because of the relatively large capacitance between grid layer 16 and substrate 12. This capacitance can absorb substantial charge without building up enough potential to re-inject many electrons back into epitaxial layer 14 or substrate 12.
In a typical embodiment the conductivity of _+
type substrate 12, p type epitaxial layer 14, and n+ type grid layer 16 are 1018-102 impurities/cm3, 1014-1016 impurities/cm3, and 1013-102 impurities/cm3, respectively.
For a 16,000 bit MOS dynamic RAM the epitaxial layer 14 might typically have a thickness of approximately 10 microns and the grid layer might have a thickness of approximately .5 to 1 micron~ The circuits and/or devices on surface 18 might typically be fahricated to a depth of approximately 1~5 microns below surface 18 of epitaxial layer 14. The size of grid layer 16 openings would typically be 5 microns on a side and the width of the grid layer 16 lines would typically be approximately 5 microns with grid layer 16 being no more positive in potential than sllbstrate 12 than approximately 3 volts.
As devices become fabricated with shorter channel len~ths and are more shallowly fa~ricated into epitaxial layer 1~, th~ impurity concentration of layer 1~ increases and the thickness thereof decreases. This allows grid layer 1~ to be closer to surface 18.
The embodiments described herein are intended to be illustrative of the general principles of the present invention. ~larious modifications are possible consistent with the spirit of the invention. For example, substrate 12, epitaxial layer 1~, and grid layer 16 could ~ ~q- ~
~u~
~ 6 ~

be of n+, n, and _+ type conductivity, respectively. Still further, in the case that an epitaxial layer is not used and circuits and/or devices are fabricated directly into a major surface of the substrate, then grid layer 16 would be located below the major surface of the substrate. Still further, the grid layer need not extend to the outer edges of the semiconductor substrate and/or epltaxial layer.
Still further, grid layer 16 can be formed wholly within epitaxial layer 1~ and not be located just at the interface of substrate 12 and epitaxial layer 14. Still further, grid layer 16 can be formed wholly within substrate 12 and not be located just at the interface of substrate 12 and epitaxial layer 14.

Claims (5)

Claims
1. A semiconductor structure comprising a semiconductor body having a bulk portion which is of a first conductivity type and having a major surface which is adapted to have electronic devices fabricated thereon, CHARACTERIZED BY
means for collecting radiation-generated current carriers in the semiconductor body comprising a grid layer located within the semiconductor body at a location which is removed from the major surface; the semiconductor body portions on opposite sides of the grid layer being in mutual electrical contact, and the distance between the grid layer and the major surface is sufficient such that the grid layer has no significant electrical effect on any electronic devices located on the major surface.
2. The semiconductor of claim 1 FURTHER CHARACTERIZED IN THAT
the grid layer is a semiconductor of a second conductivity type opposite the first conductivity type.
3. The semiconductor structure of claim 2 FURTHER CHARACTERIZED IN THAT
the semiconductor body comprises upper and lower portions which both have bulk portions of the first conductivity type; the upper portion of the semiconductor body being of lower impurity concentration than the lower portion of the semiconductor body and containing the major surface; and the grid layer being located between the upper and lower portions of the semiconductor body.
4. The semiconductor structure of claim 3 FURTHER CHARACTERIZED IN THAT
the upper portion of the semiconductor body is an epitaxial layer and the lower portion of the semiconductor body is a semiconductor substrate.
5. The semiconductor structure of claim 4 wherein the epitaxial layer, the grid layer, and the semiconductor substrate are of p, n+, and p+ type conductivity, respectively.
CA000415567A 1981-12-04 1982-11-15 Collector for radiation-generated current carriers in a semiconductor structure Expired CA1200622A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US32759181A 1981-12-04 1981-12-04
US327,591 1981-12-04

Publications (1)

Publication Number Publication Date
CA1200622A true CA1200622A (en) 1986-02-11

Family

ID=23277188

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000415567A Expired CA1200622A (en) 1981-12-04 1982-11-15 Collector for radiation-generated current carriers in a semiconductor structure

Country Status (4)

Country Link
JP (2) JPS58105566A (en)
CA (1) CA1200622A (en)
DE (1) DE3244482A1 (en)
GB (1) GB2110877B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2757685B1 (en) * 1996-12-24 1999-05-14 Commissariat Energie Atomique HIGH RESISTIVITY SEMICONDUCTOR IONIZING RADIATION DETECTION DEVICE

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL6709192A (en) * 1967-07-01 1969-01-03
NL186665C (en) * 1980-03-10 1992-01-16 Philips Nv SEMICONDUCTOR DEVICE.

Also Published As

Publication number Publication date
JPS58105566A (en) 1983-06-23
JPS6120062U (en) 1986-02-05
DE3244482A1 (en) 1983-06-16
GB2110877B (en) 1985-10-02
GB2110877A (en) 1983-06-22

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