EP0110211A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Bipolar transistor integrated circuit and method for manufacturing
Assignee: International Business Machines Corp
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Filing: 1983-11-10
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Granted: —
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Expires: 2003-11-10
Abstract
Abstract A metal silicide contact to silicon devices which has broad application to almost all of the variety of silicon semiconductor devices is described. This contact with a substantial side component has particular advantage as the base contact for a bipolar transistor. Subsequent to the formation of the metal silicide contact layer (40) the surface of said metal silicide is thermally oxidized to form a silicon dioxide layer (42) thereover. This causes the silicide contact structure to sink into the silicon body to a depth at least as great as the emitter-base junction depth. The metal silicide contact (40) itself is contacted by contact elements (52) reaching from the surface through said silicon dioxide layer (42).
Inventors
- 👤 Jacob Riseman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 12:08
CPC Classifications
H; H10; H10D; H10D62/00; H10D62/80; H10D62/83; H10D64/00; H10D64/01; H10D64/011; H10D64/0111; H10D64/0112; H10D64/012; H10D64/0121; H10D64/20; H10D64/27; H10D64/281; H10D64/60; H10D64/62
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
99 words
Method for making an electrical contact having a significant side component to a silicon semiconductor device comprising the formation of a metal silicide contact (40) on the surface of a silicon body, characterized by the steps of: thermally oxidizing the surface of said metal silicide (40) to form a silicon dioxide layer (42) thereover and resulting in moving said metal silicide contact into said silicon body to the extent that said side contact component is formed; forming an opening in said silicon dioxide layer (42) to said metal silicide; and making electrical contact (52) to said metal silicide contact.
Claim 2
Dependent Claim
99 words
Method for making an electrical contact having a significant side component to a silicon semiconductor device comprising the formation of a metal silicide contact (40) on the surface of a silicon body, characterized by the steps of: thermally oxidizing the surface of said metal silicide (40) to form a silicon dioxide layer (42) thereover and resulting in moving said metal silicide contact into said silicon body to the extent that said side contact component is formed; forming an opening in said silicon dioxide layer (42) to said metal silicide; and making electrical contact (52) to said metal silicide contact.
Claim 3
Dependent Claim
27 words
The method of claim 1 wherein the said body is monocrystalline silicon and the said metal silicide (40) is located upon a highly doped semiconductor region (34).
Claim 4
Dependent Claim
26 words
The method of claim 1 or 2 wherein the step of said thermally oxidizing is performed in a wet oxygen atmosphere at a temperature above 900°C.
Claim 5
Independent Claim
51 words
The method of one of the preceding claims wherein the step of thermally oxidizing is continued until between about 100 to 350 nanometers of silicon dioxide (42) is formed upon said metal silicide layer (40) and said metal silicide has been moved into said body between about 50 to 175 nanometers.
Claim 6
Independent Claim
26 words
The method of one of the preceding claims wherein said metal silicide is selected from the group consisting of tantalum silicide, tungsten silicide and molybdenum silicide.
Claim 7
Independent Claim
366 words
The method of one of the preceding claims applied for the formation of a bipolar transistor with a metal silicide base contact having a significant side contact component, comprising the steps of: providing a silicon semiconductor body (20) having a subcollector region (21) and having on one major surface regions of monocrystalline silicon dielectrically isolated (25) from other such regions; providing dielectric isolation (26) between the emitter-base portion and collector reach-through portion (24) of each of said regions designated to contain a bipolar transistor; sequentially depositing layers (30, 31, 32) on said major surface of polycrystalline silicon and an insulator in that order (Fig. 1); removing said layers of polycrystalline silicon and insulator and forming openings to said monocrystalline silicon above portions designated to be base contact areas and leaving said layer covering the designated emitter portion (Fig. 2); forming the extrinsic base region (34) of said bipolar transistor through said openings; forming a conformal insulator layer upon both the substantially horizontal regions and substantially vertical regions of said major surface; anisotropically etching said insulator layer to substantially remove said horizontal layer and to provide a narrow dimensioned vertical insulator (36) on the vertical sidewalls of said monocrystalline silicon and said layers (Fig. 3); depositing a layer of a refractory metal over said major surface; heating the structure to a temperature sufficient to cause the formation of a refractory metal silicide (40) where said refractory metal is on said portions of monocrystalline silicon designated to be base contact; removing by etching the unreacted said refractory metal from over insulating layers; thermally oxidizing the surface of said refractory metal silicide to form a silicon dioxide layer (42) thereover and resulting in moving said metal silicide (40) into the said monocrystalline silicon and providing said base contact having a significant side contact component (Fig. 4); reactive ion etching said major surface to remove said insulator layer covering said polycrystalline silicon layer (30) over said designated emitter portion which leaves a portion of said silicon dioxide layer (42) over said refractory metal silicide (40, Fig. 5); forming the emitter region (46, Fig. 6); and making electrical contact (50, 52, 54) to the elements of said bipolar transistor (Fig. 7).
Claim 8
Dependent Claim
50 words
The method of claim 6 wherein following said removing said layers of polycrystalline silicon (30), silicon dioxide (31), silicon nitride (32) and forming openings to said monocrystalline silicon, the step of anisotropically etching said monocrystalline silicon through said openings to a desired depth with substantially vertical side walls (Fig. 2A).
Claim 9
Dependent Claim
27 words
The method of claim 6 or 7 wherein the depth to which said metal silicide moves into said monocrystalline silicon is between about 150 to 350 nanometers.
Claim 10
Independent Claim
26 words
The method of one of claims 6 - 8 wherein the said monocrystalline silicon is etched to a depth greater than the planned emitter-base junction depth.
Claim 11
Independent Claim
62 words
The method of one of claims 6 - 9 wherein said forming the emitter region (46) includes ion implanting conductivity imparting impurities of the type the emitter region is planned into the polycrystalline silicon layer (30) over said designated emitter portion; and heating to drive said impurities from said polycrystalline silicon layer into said designated emitter portion to form said emitter region.
Claim 12
Independent Claim
37 words
The method of one of the preceding claims wherein said insulator layer is a composite layer (31, 32) of a layer of silicon dioxide upon said polycrystalline silicon layer (30) and silicon nitride upon said silicon dioxide.
Claim 13
Dependent Claim
98 words
An electrical contact structure for a silicon semiconductor device, preferably made in accordance with the method of one of the preceding claims, comprising a silicon semiconductor body having at a principal surface a metal silicide contact to a region of said body, characterized in that the contact structure (40) is located at least partially below said surface and provides a significant side component; that a silicon dioxide layer (42) is provided on the top surface of said metal silicide; and that an electrical contact element (52) is provided to said metal silicide through said silicon dioxide layer (42).
Claim 14
Dependent Claim
23 words
The electrical contact structure of claim 12 wherein the said metal silicide is located upon a highly doped semiconductor region and is ohmic.
Claim 15
Dependent Claim
25 words
The electrical contact structure of claim 12 wherein the said metal silicide is located upon a lightly doped semiconductor region and is a Schottky contact.
Claim 16
Dependent Claim
54 words
The electrical contact structure of claims 12 or 13 wherein the said silicon is monocrystalline, said device is a bipolar transistor, the said metal silicide contact is to the extrinsic base region of said transistor, and said contact extends into said body to a depth at least as great as the emitter-base junction depth.
Claim 17
Dependent Claim
32 words
The electrical contact structure of claim 15 wherein the said emitter-base junction depth is between about 100 to 250 nanometers and metal silicide contact depth is between about 150 to 350 nanometers.
Claim 18
Dependent Claim
29 words
The electrical contact structure of one of claims 12 - 16 wherein said metal silicide is selected from the group consisting of tantalum silicide, tungsten silicide and molybdenum silicide.
Claim 19
Dependent Claim
146 words
A bipolar transistor integrated circuit having a highly conductive refractory metal silicide base contact of the type as set forth in claims 12 to 17 and preferably manufactured according to one of claims 1 - 11 comprising: a plurality of bipolar transistors electrically isolated from one another in a monocrystalline silicon body; each of said transistors comprising an emitter region, a base region including extrinsic and intrinsic base regions, said extrinsic base region surrounding said emitter region in said semiconductor body, said intrinsic base region forming a junction with said emitter region substantially in one plane, a polycrystalline silicon ohmic contact to said emitter region, a metal silicide ohmic contact to said extrinsic base region, an insulator barrier separating said polycrystalline silicon contact from said metal silicide contact, said metal silicide contact extending into said silicon body so as to produce a significant side contact component.
Claim 20
Dependent Claim
43 words
A bipolar transistor integrated circuit of claim 18 wherein the surface of said extrinsic base region under said base contact is lower than the top surface of said body by an amount greater than the emitter-base junction to thereby prevent emitter side injection.
References Cited (Backward Citations)
No citation records indexed.
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