US4642669A
Expired / Lapsed
US
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Semiconductor device having a blocking capability in only one direction
Assignee: BBC Brown Boveri AG Switzerland
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Filing: 1984-12-07
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Granted: 1987-02-10
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Expires: 2004-12-07
Abstract
Abstract For improving the dynamic characteristics of semiconductor components required to absorb high reverse voltages only in one polarity (diodes, reverse-conducting thyristors and asymmetric thyristors), in many cases structures having an n base consisting of two layers are used. In order to improve the reverse-voltage capability, it is proposed, in a semiconductor component having at least one pn - n sequence of layers, to select the thickness (S) and the doping of an n stop layer (4) in such a way that the following applies: ##EQU1## where e=elementary charge, ε=dielectric constant of the semiconductor, N D =donor concentration, X=path coordinate, 0.8≦k≦1.0 and E n =field strength at the n - n junction. The effect of this measure is that the geometric conditions of the edge chamfering are less stringent. The edge can also be shaped by means of conventional etching processes.
Inventors
- 👤 Peter Roggwiller
- 👤 Roland Sittig
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 16:12
CPC Classifications
H; H10; H10D; H10D62/00; H10D62/60; H10D18/00; H10D18/241; H10D62/10; H10D62/102; H10D62/103; H10D62/104; H10D8/00
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
202 words
A semiconductor device having a blocking capbility in only one direction, comprisng: an anode; a cathode; a plurality of differently doped layers stacked along a main axis between said anode and said cathode, said doped layers including, a first highly doped p + layer provided aside said anode, a second highly doped n + layer provided aside said cathode, a third layer with a low-level n - doping provided between said first and second layers, a fourth n-doped stopping layer with a doping concentration lying in between the doping concentrations of said second and third layers provided adjoining said third layer on one side, wherein said stopping layer has a thickness S and a number of donor atoms selected so as to satisfy the equation: ##EQU3## with e=elementary charge ε=dielectric constant of the semiconductor material of said device, N D =donor concentration in said stopping layer (in cm -3 ), x=path coordinate of an integration path parallel to said main axis of said device (in cm), k=numerical constant with 0.8≦K≦1.0, E n =electrical field strength at the junction between said third and fourth layers at the breakdown voltage of said device; and a recess provided at the edge of said stopping layer.
Claim 2
Dependent Claim
202 words
A semiconductor device having a blocking capbility in only one direction, comprisng: an anode; a cathode; a plurality of differently doped layers stacked along a main axis between said anode and said cathode, said doped layers including, a first highly doped p + layer provided aside said anode, a second highly doped n + layer provided aside said cathode, a third layer with a low-level n - doping provided between said first and second layers, a fourth n-doped stopping layer with a doping concentration lying in between the doping concentrations of said second and third layers provided adjoining said third layer on one side, wherein said stopping layer has a thickness S and a number of donor atoms selected so as to satisfy the equation: ##EQU3## with e=elementary charge ε=dielectric constant of the semiconductor material of said device, N D =donor concentration in said stopping layer (in cm -3 ), x=path coordinate of an integration path parallel to said main axis of said device (in cm), k=numerical constant with 0.8≦K≦1.0, E n =electrical field strength at the junction between said third and fourth layers at the breakdown voltage of said device; and a recess provided at the edge of said stopping layer.
Claim 3
Dependent Claim
70 words
The semiconductor device as claimed in claim 1, wherein said recess has the following properties: B≧W and S≦T≦W/2, with B=lateral extension of said recess in a region where said stopping layer has been completely removed, W=thickness of the space charge zone of the pn-junction of said device at the breakdown voltage of said device, T=maximum depth of said recess parallel to said main axis measured from the cathode surface plane.
Claim 4
Dependent Claim
68 words
The semiconductor device as claimed in claim 2, wherein: said stopping layer is located between said third and second layers; said second layer is embedded into said stopping layer; between the edge of said second layer and said recess a distance D remains in which said stopping region is retained; and said distance D is equal to or greater than said thickness W of said space charge zone.
Claim 5
Dependent Claim
86 words
The semiconductor device as claimed in claim 2, comprising: said stopping layer located between said third and first layers; a fifth p-doped layer adjoining said third layer on the other side of said third layer; said first layer embedded into said stopping layer; and the donor concentration of said stopping layer increased in a region near said first layer with respect to a region far from said first layer, whereby the donor concentration in said letter region corresponds to the donor concentration of said integral equation.
Claim 6
Dependent Claim
100 words
The semiconductor device as claimed in claim 2, comprising: said stopping layer located between said third and first layers; a fifth p-doped layer adjoining said third layer on the other side of said third layer; said first layer embedded into said stopping layer; and an additional recess provided in an edge region of said stopping layer, said additional recess reducing said thickness S of said stopping layer in the region of the junction of the stopping layer with said third layer to such an extent that said space charge zone extends to a surface at the side of said anode.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-02-09 | 1990-08-11 | 1991-02-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-09 | 1994-08-11 | 1995-02-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-09 | 1998-08-11 | 1999-02-10 | $7700.00 | Window Closed / Lapsed |