EP0488625A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Structure and method for use in a semiconductor field oxidation process
Assignee: MagnaChip Semiconductor Ltd
•
Filing: 1991-11-25
•
Granted: —
•
Expires: 2011-11-25
Abstract
Abstract In a process for forming field oxide regions (40) between active regions in a semiconductor substrate (10), pad oxide, polysilicon and first silicon nitride layers (12,14,16) are successively formed over substrate active regions. The first nitride layer (16), polysilicon layer (14), pad oxide layer (12) and a portion of the substrate (10) are then selectively etched to define field oxide regions with substantially vertical sidewalls (21). A second silicon nitride (32) is provided on the substantially vertical sidewalls (21), and field oxide (40) is grown in the field oxide regions. The first silicon nitride, polysilicon and pad oxide layers (16,14,12) are then removed. The employment of the polysilicon layer (14) prevents the exposure of corners (44) between the field oxide (40) and active regions if an overetch occurs during the removal of the pad oxide layer (12).
Inventors
- 👤 Steven S. Lee
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 18:41
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/60; H10P14/61; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/012; H10W10/0128; H10W10/10; H10W10/13
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
94 words
A structure for fabricating an integrated circuit, including a silicon substrate (10) and a pad oxide layer (12) overlying said substrate (10), characterized by a polysilicon layer (14) overlying said pad oxide layer (12); a first nitride layer (16) overlying said polysilicon layer (14); an opening (20) through said first nitride (16) polysilicon (14) and pad oxide (12) layers and into said silicon substrate (10) defining a region for field oxide growth, having a sidewall surface (21) and an adjoining bottom surface (30); and a second nitride layer (32) overlying said sidewall surface (21).
Claim 2
Dependent Claim
57 words
A structure according to claim 1, characterized in that said polysilicon layer (14) has a nominal thickness of 3-100 nm, said pad oxide layer (12) has a nominal thickness of 5-100 nm, said first nitride layer (16) has a nominal thickness of 10-500 nm, and said second nitride layer (32) has a nominal thickness of 5-25 nm.
Claim 3
Dependent Claim
23 words
A structure according to claim 1, characterized in that said sidewall surface (21) is substantially normal with respect to said bottom surface (30).
Claim 4
Dependent Claim
36 words
A structure according to any one of the preceding claims, characterized in that a thin screening oxide layer (26) is disposed between said sidewall surface (21) of said opening (20) and said second nitride layer (32).
Claim 5
Dependent Claim
22 words
A structure according to claim 4, characterized in that said screening oxide layer (26) has a thickness of less than 20 nm.
Claim 6
Dependent Claim
26 words
A structure according to any one of the preceding claims, characterized in that said opening (20) within said substrate (10) is between 30 and 150 nm.
Claim 7
Dependent Claim
120 words
A process for forming field oxide regions between active regions in a semiconductor substrate (10), including the step of forming cover said active regions a pad oxide layer (12), characterized by the steps of forming over said pad oxide layer (12) a polysilicon layer (14); forming over said polysilicon layer (14) a first silicon nitride layer (16); selectively etching through said first nitride layer (16), said polysilicon layer (14) and said pad oxide layer (12), and into said substrate (10) to define field oxide regions having sidewalls (21); providing a second silicon nitride layer (32) on said sidewalls (21); growing field oxide (40) in said field oxide regions; and removing said first silicon nitride, polysilicon and pad oxide layers (16,14,12).
Claim 8
Dependent Claim
33 words
A process according to claim 7, characterized by the step of forming a gate oxide layer (50) over the structure remaining after removing said first silicon nitride, polysilicon and pad oxide layers (16,14,12).
Claim 9
Dependent Claim
86 words
A process according to claim 7 or 8, characterized in that said field oxide (40) is grown by the steps of: oxidizing the exposed substrate (10) and second silicon nitride (32) in a proportion to effectuate concurrent oxidation and lifting and bending, beginning at the low edge of the retained sidewall silicon nitride (32); and continuing the oxidation of the polysilicon (14) and substrate (10) and the lifting of the sidewall silicon nitride (32) until the upper surface of the oxidized substrate reaches a predetermined level.
Claim 10
Dependent Claim
59 words
A process according to any one of claims 7 to 9, characterized by the steps of, prior to providing said second silicon nitride layer (32), forming a relatively thin screening oxide layer (26) on said sidewalls (21); and doping selected regions of said substrate (10) through selected horizontally disposed surfaces of said substrate (10) underlying said field oxide regions.
Claim 11
Dependent Claim
93 words
A process according to any one of claims 7 to 10, characterized in that said step of providing said second silicon nitride layer (32) includes the steps of: forming a conformal second silicon nitride layer (28), over the patterned structure of the substrate and layers, including the substantially vertical sidewalls (21), to a nominal thickness of less than 25 nm; and removing the horizontally disposed second silicon nitride layer (28) to expose horizontally disposed surfaces (30) of said substrate (10), while retaining a second silicon nitride layer (32) on the said sidewalls (21).
Claim 12
Dependent Claim
74 words
A process according to any one of claims 7 to 11, characterized in that said polysilicon layer (14) is formed to a nominal thickness of 3-100 nm, said pad oxide layer (12) is formed to a nominal thickness of 5-100 nm, and said first nitride layer (16) is formed to a nominal thickness of 10-500 nm, and in that the depth of the etch into said substrate (10) is between 30 and 150 nm.
Claim 13
Dependent Claim
41 words
A process according to any one of claims 7 to 12, characterized in that said field oxide (40) is grown to a level at least as high as the interface between said polysilicon layer (14) and said first nitride layer (16).
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.