EP0111086B1
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EP
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Process for making sub-micrometric structures and use of this process in making deep dielectric isolation regions with a sub-micrometric width in a semiconductor body
Assignee: IBM Deutschland GmbH
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Filing: 1983-10-05
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Granted: 1989-03-08
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Expires: 2003-10-05
Abstract
No abstract record available.
Inventors
- 👤 Hans-Joachim Dr. Trumpp
- 👤 Johann Dr. Greschner
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 20:34
CPC Classifications
H; H10; H10P; H10P76/00; H10P76/40; H10P76/408; H10P76/4085; H10P50/00; H10P50/69; H10P50/691; H10P50/693; H10P50/695; H10P50/696; H10P76/4088; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/014; H10W10/10; H10W10/17; Y; Y10; Y10S; Y10S438/00; Y10S438/942; Y10S438/947
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
274 words
Method of making structures with dimensions in the sub-micrometer range in a layer arranged on a silicon substrate, characterized in that a) first, a first isolating layer (2; Fig. 3) or a sequence of layers (2a, 2b; Fig. 14) is applied on a silicon substrate (1); b) that onto the layer (2, 2b) a polymeric layer (3) is applied, and parts of this layer are removed again, forming polymeric structures (3) which beside horizontal surfaces show substantially vertical surfaces at their edges (Fig. 4); c) that on the horizontal and substantially vertical surfaces of the polymeric structures, as well as on the exposed horizontal regions of the first isolating layer (2, 2b) a second isolating layer (6) is applied (Fig. 5); d) that the horizontal regions of the second isolating layer (6), as well as the polymeric structure (3) are removed by reactive ion etching in such a manner that very narrow walls of the second isolating layer (6) remain on the first isolating layer (2) (Fig. 6); e1) that in the case of positive lithography the walls directly serve as a mask for forming structures in the layer (2a; Fig. 14) with dimensions in the submicrometer range, and e2) that in the case of negative lithography the walls are embedded in the desired mask material (7) which for obtaining an improved surface planarity is partly removed again (Fig. 7A); f) that the walls of the second isolating material (6) embedded in the mask material (7) are removed by etching, with resulting mask openings (8) with dimensions in the submicrometer range which are extended by reactive ion etching to the substrate (1) (Fig. 8).
Claim 2
Dependent Claim
274 words
Method of making structures with dimensions in the sub-micrometer range in a layer arranged on a silicon substrate, characterized in that a) first, a first isolating layer (2; Fig. 3) or a sequence of layers (2a, 2b; Fig. 14) is applied on a silicon substrate (1); b) that onto the layer (2, 2b) a polymeric layer (3) is applied, and parts of this layer are removed again, forming polymeric structures (3) which beside horizontal surfaces show substantially vertical surfaces at their edges (Fig. 4); c) that on the horizontal and substantially vertical surfaces of the polymeric structures, as well as on the exposed horizontal regions of the first isolating layer (2, 2b) a second isolating layer (6) is applied (Fig. 5); d) that the horizontal regions of the second isolating layer (6), as well as the polymeric structure (3) are removed by reactive ion etching in such a manner that very narrow walls of the second isolating layer (6) remain on the first isolating layer (2) (Fig. 6); e1) that in the case of positive lithography the walls directly serve as a mask for forming structures in the layer (2a; Fig. 14) with dimensions in the submicrometer range, and e2) that in the case of negative lithography the walls are embedded in the desired mask material (7) which for obtaining an improved surface planarity is partly removed again (Fig. 7A); f) that the walls of the second isolating material (6) embedded in the mask material (7) are removed by etching, with resulting mask openings (8) with dimensions in the submicrometer range which are extended by reactive ion etching to the substrate (1) (Fig. 8).
Claim 3
Dependent Claim
106 words
Method as claimed in claim 1, characterized in that for making the polymeric structures (3) with horizontal and at their edges substantially vertical surfaces layers (3, 4 and 5) are applied on the isolating layer (2) (Fig. 3) with the polymeric layer (3) directly applied on the isolating layer (2) consisting of polyimide, or of a photoresist, and the layer (4) of plasma silicon nitride or oxide, and the layer (5) of a photoresist; that the desired pattern is made in the top layer (5) and transferred by reactive ion etching into the plasma nitride layer (4) and into the polymeric layer (3) respectively (Fig. 4).
Claim 4
Dependent Claim
75 words
Method as claimed in claims 1 and 2, characterized in that of the layers (3, 4 and 5) the layer (3) consists of a positive photoresist and is between 1.0 µm and 2.0 ¡.Lm thick, that the next layer (4) consists of plasma silicon nitride and is between 0.2 µm and 0.5 µm thick, and that the top layer (5) consists of a highly sensitive photoresist and is between 0.5 µm to 1.5 µm thick.
Claim 5
Dependent Claim
56 words
Method as claimed in any one of claims 1 to 3, characterized in that the pattern is transferred from the layer (5) by reactive ion etching with CF 4 into the layer (4) of plasma nitride, and by reactive ion etching with oxygen at a pressure of less than 5 ubar into the resist layer (3).
Claim 6
Dependent Claim
81 words
Method as claimed in claim 1, characterized in that for making polymeric structures (3) with horizontal and that their edges, substantially vertical surfaces a modified image reversal process is applied where a photosensitive layer of a positive photoresist containing 1-hydroxyethyl-2-alkyl-imidazoline is applied on a substrate (1, 2), exposed image-wise cured at 105°C for 10 to 20 minutes, then blanket-exposed and developed in an alkaline developer, with a resist image negative relative to the original pattern and having substantially vertical sidewalls resulting.
Claim 7
Dependent Claim
58 words
Method as claimed in claim 1, characterized in that on the silicon substrate (1) as a first isolating layer (2) a silicon dioxide layer is produced by means of thermal oxidation, or a silicon nitride layer by means of deposition out of a silane, ammonia and argon-containing atmosphere, or a double layer of silicon dioxide and silicon nitride.
Claim 8
Dependent Claim
80 words
Method as claimed in any one of claims 1 and 6, characterized in that in the case of silicon dioxide as first isolating layer plasma silicon nitride or polysilicon (6) are deposited as second isolating layer on the horizontal and substantially vertical surfaces of the polymeric structure (3) and the horizontal surface of the first isolating layer (2) and in the case of silicon nitride as the first isolating layer plasma silicon dioxide is deposited as the second isolating layer.
Claim 9
Dependent Claim
67 words
Method as claimed in claim 1, characterized in that silicon nitride (6) is deposited on the horizontal and substantially vertical surfaces of the resist structure (3) and the isolating layer (2) by plasma deposition out of an atmosphere containing silane, ammonia and argon, at a pressure of approximately 1 µbar, an energy of 100 Watt (energy density of 0.05 Watt/cm 2 ) and a temperature of 210°C.
Claim 10
Dependent Claim
44 words
Method as claimed in any one of claims 1 and 8, characterized in that the horizontal regions of the silicon nidride layer (6) are removed by reactive ion etching with CF 4 , and the resist structure (3) by reactive ion etching with oxygen.
Claim 11
Dependent Claim
74 words
Method as claimed in claim 1, characterized in that in the case of positive lithography layer (2a; Fig. 14) consists of the desired mask material selected from the group of a polymeric material such as photoresist, polyimide, or of inorganic material such as SiO 2 , Si 3 N 4 , polysilicon, metal, or combinations thereof, and that a thin dielectric layer (2b) of plasma nitride or oxide is arranged on the layer (2a).
Claim 12
Dependent Claim
80 words
Method as claimed in any one of claims 1 and 10, characterized in that the dielectric layer (2b) and the layer (2a) is removed in the regions not covered by the sidewall mask (6) by means of reactive ion etching, and that subsequently the sidewall mask and the remains of the dielectric layer (2b) therebeneath are etched off, with a mask with the dimensions of the original pattern, but consisting of the material of the layer (2b; Fig. 15) resulting.
Claim 13
Dependent Claim
71 words
Method as claimed in claim 1, characterized in that in the case of negative lithography onto the substrate (1, 2) with the sidewalls (6) mask materials (7) of the group of polymeric materials as photoresist or polyimide or glass are spin- coated, or materials as Si0 2 , Si 3 N 4 , MgO, polysilicon or AI 2 0 3 or metals are applied by sputtering, or by chemical vapor deposition.
Claim 14
Dependent Claim
73 words
Method as claimed in any one of claims 1 and 12, characterized in that onto the substrate (1, 2) with sidewalls of silicon nitride silicon dioxide is deposited as mask material (7) by means of cathode sputtering, a first, approximately 1.3 1 1m thick layer being applied under the usual conditions, and a second, approximately 0.5 µm thick silicon dioxide layer being deposited with increased anode efficiency to achieve an improved surface planarity.
Claim 15
Dependent Claim
71 words
Method as claimed in any one of claims 1 and 12, characterized in that an approximately 0.5 11m thick silicon dioxide layer (7a) is chemically vapor deposited uniformly round the silicon nitride walls (6), and that subsequently by means of cathode sputtering an approximately 1 11m thick silicon dioxide layer (7b) is deposited with increased anode efficiency to increase the silicon dioxide layer thickness, and to achieve an improved surface planarity.
Claim 16
Dependent Claim
35 words
Method as claimed in claim 14, characterized in that instead of the silicon dioxide layer (7b) or the silicon dioxide layers (7a and 7b) a photoresist layer is spun-on and etched back for surface planarization.
Claim 17
Dependent Claim
76 words
Method as claimed in claim 1, characterized in that for removing the sidewalls (6) the silicon dioxide layer (7) or the photoresist layer, respectively, is blanket removed by reactive ion etching until the peaks of the sidewalls (6) are exposed, and that subsequently the silicon nitride or oxide is removed by plasma etching or wet etching, and that the openings (8) are extended to the surface of the silicon substrate (1) by blanket reactive ion etching.
Claim 18
Dependent Claim
55 words
Method as claimed in claim 16, characterized in that following the removal of the silicon dioxide layer (7) the silicon nitride walls are removed by plasma etching with CF 4 , and that the openings (8) are extended to the surface of the silicon substrate (1) by blanket reactive ion etching with CF 4 .
Claim 19
Dependent Claim
122 words
Method as claimed in one or several of claims 1 to 17 in its application to making a deep dielectric isolation with submicrometer width (9) in a silicon body (1), characterized in that through the finished mask (7) trenches (9) are etched into the silicon substrate (1) by reactive ion etching with chlorine and/or oxygen- containing gases (Fig. 10); that the trenches (9) are filled by thermal oxidation exclusively (Fig. 11), or with thermal oxide (11), nitride (12) and a synthetic material (13; Fig.13); and that if filling takes place by thermal oxidation exclusively the blanket etching of the oxide off the surface of the silicon body (1) is followed by a reoxidation, with a silicon dioxide layer (10) resulting (Fig. 12).
Claim 20
Dependent Claim
47 words
Method as claimed in claim 18, characterized in that the trenches (9) in the silicon substrate (1) are made by reactive ion etching with chlorine/argon; SF 6/ chlorine/helium; CCl 2 F 2 /oxygen or SiF 4/ chlorine/helium or argon gas mixtures through the silicon dioxide mask (7).
Claim 21
Dependent Claim
35 words
Method as claimed in any one of claims 18 and 19, characterized in that if deep and shallow trenches are made simultaneously, the shallow trenches are covered during the additional etching of the deep trenches.
Claim 22
Dependent Claim
65 words
Method as claimed in any one of claims 18 to 20, characterized in that the trenches are filled by thermal oxidation with silicon dioxide (Fig. 11), or that a thermal oxidation to produce approximately 25 nm silicon dioxide (11), a vapor deposition to produce approximately 50 nm silicon nitride (12) are performed, and that the trenches are then completely filled with polyimide (13) (Fig. 13).
Claim 23
Dependent Claim
61 words
Method as claimed in any one of claims 18 and 21, characterized in that if the trenches are filled by thermal oxidation the oxide is removed from the silicon substrate surface (1) by blanket reactive ion etching with CHF 3 , and that subsequently the silicon substrate (1) is reoxidized to an oxide layer thickness (10) required for the subsequent processes.
References Cited (Backward Citations)
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