US5310691A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of manufacturing semiconductor device including formation of alignment mark
Assignee: Mitsubishi Electric Corp
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Filing: 1993-05-27
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Granted: 1994-05-10
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Expires: 2013-05-27
Abstract
Abstract A p - semiconductor substrate has a surface which is high in a memory cell region and low in a peripheral circuit region. An n + buried semiconductor layer of uniform thickness is formed on the substrate. An n - epitaxial layer formed on the buried semiconductor layer is thin in the memory cell region and thick in the peripheral circuit region, so that the surface of the epitaxial layer can be flat. A concave or convex step is formed on the surface of the epitaxial layer in a boundary portion between the memory cell region and the peripheral circuit region in order to use it as an alignment mark in a later processing step.
Inventors
- 👤 Kakutaro Suda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 22:48
CPC Classifications
H; H10; H10D; H10D62/00; H10D62/10; H10D62/13; H10D62/137; H10B; H10B10/00; H10B10/18; Y; Y10; Y10S; Y10S438/00; Y10S438/975
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
170 words
A method of manufacturing a semiconductor device, comprising the steps of: (a) preparing a first conductivity type semiconductor substrate; (b) selectively removing a surface of said semiconductor substrate to thereby provide said semiconductor substrate with a first region formed with a relatively high surface and a second region adjacent to the first region and formed with a relatively low surface; (c) forming a second conductivity type buried semiconductor layer of a relatively high impurity concentration with substantially uniform thickness formed on said semiconductor substrate in said first and second regions; (d) growing a second conductivity type epitaxial layer of a relatively low impurity concentration in substantially uniform thickness on said buried semiconductor layer; and (e) selectively removing said epitaxial layer in said first region to thereby equalize the height of a portion of the surface of said epitaxial layer in said first and second regions, and to provide said surface of said epitaxial layer with a concave or convex step in a boundary portion between said first and second regions.
Claim 2
Independent Claim
170 words
A method of manufacturing a semiconductor device, comprising the steps of: (a) preparing a first conductivity type semiconductor substrate; (b) selectively removing a surface of said semiconductor substrate to thereby provide said semiconductor substrate with a first region formed with a relatively high surface and a second region adjacent to the first region and formed with a relatively low surface; (c) forming a second conductivity type buried semiconductor layer of a relatively high impurity concentration with substantially uniform thickness formed on said semiconductor substrate in said first and second regions; (d) growing a second conductivity type epitaxial layer of a relatively low impurity concentration in substantially uniform thickness on said buried semiconductor layer; and (e) selectively removing said epitaxial layer in said first region to thereby equalize the height of a portion of the surface of said epitaxial layer in said first and second regions, and to provide said surface of said epitaxial layer with a concave or convex step in a boundary portion between said first and second regions.
Claim 3
Dependent Claim
72 words
A method of manufacturing a semiconductor device in accordance with claim 1, wherein said step (b) includes the steps of: forming a first mask in said first region; performing first selective oxidation using said first mask to form a first oxide film on said semiconductor substrate in said second region in order to make said semiconductor substrate thinner in said second region; and removing said first mask and said first oxide film.
Claim 4
Dependent Claim
42 words
A method of manufacturing a semiconductor device in accordance with claim 1, wherein said step (c) includes the steps of: introducing second conductivity type impurities into the surface of said semiconductor substrate; and diffusing said impurities to form said buried semiconductor layer.
Claim 5
Dependent Claim
72 words
A method of manufacturing a semiconductor device in accordance with claim 2, wherein said step (e) includes the steps of: forming a second mask in said second region; performing second selective oxidation using said second mask to form a second oxide film on said epitaxial layer in said first region in order to make said epitaxial layer thinner in said first region, and removing said second mask and said second oxide film.
Claim 6
Dependent Claim
35 words
A method of manufacturing a semiconductor device in accordance with claim 4, wherein said second mask has an edge set on the second region apart from the boundary portion between said first and second regions.
Claim 7
Dependent Claim
35 words
A method of manufacturing a semiconductor device in accordance with claim 4, wherein said second mask has an edge set on the first region apart from the boundary portion between said first and second regions.
Claim 8
Dependent Claim
26 words
A method of manufacturing a semiconductor device in accordance with claim 4, wherein said first and second selective oxidation steps are performed under the same condition.
Claim 9
Dependent Claim
47 words
A method of manufacturing a semiconductor device in accordance with claim 1, further comprising the step of: forming a plurality of trench isolating layers reaching said semiconductor substrate from the surface of said epitaxial layer to divide first and second regions into a plurality of element regions.
Claim 10
Dependent Claim
36 words
A method of manufacturing a semiconductor device in accordance with claim 8, wherein said step of forming a plurality of trench isolating layers is performed by using said concave or convex step as an alignment mark.
Claim 11
Dependent Claim
28 words
A method of manufacturing a semiconductor device in accordance with claim 8, further comprising the step of: forming transistors in predetermined ones of said plurality of element regions.
Claim 12
Dependent Claim
51 words
A method of manufacturing a semiconductor device in accordance with claim 1, wherein said step (b) includes the steps of: forming a first mask in said first region; performing first plasma etching using said first mask to make said semiconductor substrate thinner in said second region., and removing said first mask.
Claim 13
Dependent Claim
51 words
A method of manufacturing a semiconductor device in accordance with claim 11, wherein said step (e) includes the steps of: forming a second mask in said second region; performing second plasma etching using said second mask to make said epitaxial layer thinner in said first region; and removing said second mask.
Claim 14
Dependent Claim
35 words
A method of manufacturing a semiconductor device in accordance with claim 12, wherein said second mask has an edge set on the second region apart from the boundary portion between said first and second regions
Claim 15
Dependent Claim
35 words
A method of manufacturing a semiconductor device in accordance with claim 12, wherein said second mask has an edge set on the first region apart from the boundary portion between said first and second regions.
Claim 16
Dependent Claim
26 words
A method of manufacturing a semiconductor device in accordance with claim 12, wherein said first and second plasma etching steps are performed under the same condition.
References Cited (Backward Citations)
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