Dynamic random access memory device and method of producing the same

Claim 1

A dynamic random access memory device comprising a plurality of dynamic cells, each of which comprises a storage capacitor (C) formed on a substrate (11), and a transfer transistor (T); the transfer transistor comprising a pair of impurity diffused regions (13,14) which are formed in the substrate and are located within an area defined by a field insulating film (12) formed on the substrate, and a gate electrode (WL1) being located between the pair of impurity diffused regions and being covered by an insulating film (15); characterized in that the storage capacitor comprises a storage electrode (26) formed by a conductive material being connected to either one (13) of the impurity diffused regions through an opening (23) formed in the insulating film, and extending above the field insulating film and the gate electrode, the storage electrode being separated from the insulating film by a gap (24₁); a dielectric film (27) being formed so as to surround an exposed surface of the storage electrode; and an opposed electrode (28) made of a conductive material being formed so as to surround the storage electrode around which the dielectric film is formed, the gap being filled with the opposed electrode.

Claim 24

A method of producing a dynamic random access memory device comprising the step of forming a transfer transistor (T) comprising a pair of impurity diffused regions (13,14) which are located within an area defined by a field insulating film (12) formed on a substrate, and a gate electrode (WL1) being located between the pair of impurity diffused regions; characterized in that the method comprises the steps of forming an insulating film (15) so as to cover the transfer transistor for insulation; forming a first conductive film (16a) on the insulating film; forming a second conductive film (16b) on the first conductive film, an etching rate with respect to the second conductive film being different from an etching rate with respect to the first conductive film; patterning the first conductive film and the second conductive film in accordance with a desired size of a storage electrode of a capacitor; selectively etching either one (16a) of the patterned first conductive film and the patterned second conductive film so that there is formed a groove; forming a dielectric film (17) around exposed surfaces of the first conductive film and the second conductive film; and forming a third conductive film (18) so as to completely cover the first and second conductive films around which the dielectric film is formed.

Claim 25

A method of producing a dynamic random access memory device comprising the step of forming a transfer transistor (T) comprising a pair of impurity diffused regions (13,14) which are located within an area defined by a field insulating film (12) formed on a substrate, and a gate electrode (WL1) being located between the pair of impurity diffused regions; characterized in that the method comprises the steps of forming an insulating film (15) so as to cover the transfer transistor for insulation; forming a first conductive film (16a) on the insulating film; forming a second conductive film (16b) on the first conductive film, an etching rate with respect to the second conductive film being different from an etching rate with respect to the first conductive film; patterning the first conductive film and the second conductive film in accordance with a desired size of a storage electrode of a capacitor; selectively etching either one (16a) of the patterned first conductive film and the patterned second conductive film so that there is formed a groove; forming a dielectric film (17) around exposed surfaces of the first conductive film and the second conductive film; and forming a third conductive film (18) so as to completely cover the first and second conductive films around which the dielectric film is formed.

Claim 28

A method of producing a dynamic random access memory as claimed in anyone of claims 18 to 20, characterized in that an impurity ion is doped into the second conductive film (16b) so that the etching rate with respect to the second conductive film (16b) is different from the etching rate with respect to the first conductive film (16a).

Claim 29

A method of producing a dynamic random access memory device as claimed in anyone of claims 18 to 21, characterized in that the first conductive film (16a) is a polysilicon film with an impurity undoped, and the second conductive film (16b) is a polysilicon film with an n⁺-type impurity doped.

Claim 30

A method of producing a dynamic random access memory as claimed in anyone of claims 18 to 22, characterized in that the step of forming the first conductive film (16a) and the step of forming the second conductive film (16b) are carried out by a plasma-assisted chemical vapor deposition process, so that the first and second film can be grown at a low temperature equal to or lower than 800 [°C].

Claim 31

A method of producing a dynamic random access memory device comprising the step of forming a transfer transistor (T) comprising a pair of impurity diffused regions (13, 14) which are located within an area defined by a field insulating film (12) formed on a substrate (11), and a gate electrode (WL1) being located between the pair of impurity diffused regions; characterized in that the method comprises the steps of forming a first film (15) so as to cover the transfer transistor for insulation; forming a second film (22) on the first film, the second film being made of a material different from the first film; forming an opening (23) in the first and second films, the either one of the first and second the impurity diffused regions being exposed through the opening; forming a first conductive film (26) on the second film; patterning the first conductive film in accordance with a desired size of a storage electrode; selectively removing the second film by isotropic etching; forming a dielectric film (27) on an exposed surface of the patterned first conductive film; and forming a second conductive film (28) so as to surround the patterned first conductive film around which the dielectric film is formed.

Claim 32

A method of producing a dynamic random access memory device comprising the step of forming a transfer transistor (T) comprising a pair of impurity diffused regions (13, 14) which are located within an area defined by a field insulating film (12) formed on a substrate (11), and a gate electrode (WL1) being located between the pair of impurity diffused regions; characterized in that the method comprises the steps of forming a first film (15) so as to cover the transfer transistor for insulation; forming a second film (22) on the first film, the second film being made of a material different from the first film; forming an opening (23) in the first and second films, the either one of the first and second the impurity diffused regions being exposed through the opening; forming a first conductive film (26) on the second film; patterning the first conductive film in accordance with a desired size of a storage electrode; selectively removing the second film by isotropic etching; forming a dielectric film (27) on an exposed surface of the patterned first conductive film; and forming a second conductive film (28) so as to surround the patterned first conductive film around which the dielectric film is formed.

Claim 35

A method of producing a dynamic random access memory device as claimed in anyone of claims 24 to 26, characterized in that the step of forming the dielectric film (27) is carried out by a thermal oxidation process in which an oxidation atmosphere is set at a low-pressure equal to or less than 10 [torr].

Claim 36

A method of producing a dynamic random access memory device as claimed in anyone of claims 24 to 26, characterized in that the dielectric film (27) is formed by depositing a silicon nitride film by low-pressure plasma vapor deposition with a pressure equal to or lower than 10 [torr].

Claim 37

A method of producing a dynamic random access memory device as claimed in anyone of claims 24 to 28, characterized in that the step of forming the second conductive film (22) is carried out by a chemical vapor deposition process in which an atmosphere is set at a low-pressure equal to or less than 10 torr .

Claim 38

A method of producing a dynamic random access memory device comprising the step of forming a transfer transistor (T) comprising a pair of impurity diffused regions which are located within an area defined by a field insulating film (15) formed on a substrate (11), and a gate electrode (WL1) being located between the pair of impurity diffused regions; characterized in that the method comprises the steps of forming a first film (15) so as to cover the transfer transistor for insulation; forming a first conductive film (36a₁) on the first film; forming a second film (32a₁) on the first conductive film, the second film being made of a material different from the first film; forming an opening (23₂) which penetrates the first film, the first conductive film and the second film, so that either one of the impurity diffused regions is exposed through the opening; forming a second conductive film (36a₂) on the exposed impurity diffused region, an inner wall of the opening and the exposed second film; patterning the first and second conductive films (36a₁, 36a₂) and the second film (32a) in accordance with a desired size of a storage electrode; selectively removing a remaining portion of the second film by isotropic etching; forming a dielectric film (37) on an exposed surface of the patterned first and second conductive films; and forming a third conductive film (38) so as to surround the patterned first and second conductive films around which the dielectric film is formed.

Claim 39

A method of producing a dynamic random access memory device comprising the step of forming a transfer transistor (T) comprising a pair of impurity diffused regions which are located within an area defined by a field insulating film (15) formed on a substrate (11), and a gate electrode (WL1) being located between the pair of impurity diffused regions; characterized in that the method comprises the steps of forming a first film (15) so as to cover the transfer transistor for insulation; forming a first conductive film (36a₁) on the first film; forming a second film (32a₁) on the first conductive film, the second film being made of a material different from the first film; forming an opening (23₂) which penetrates the first film, the first conductive film and the second film, so that either one of the impurity diffused regions is exposed through the opening; forming a second conductive film (36a₂) on the exposed impurity diffused region, an inner wall of the opening and the exposed second film; patterning the first and second conductive films (36a₁, 36a₂) and the second film (32a) in accordance with a desired size of a storage electrode; selectively removing a remaining portion of the second film by isotropic etching; forming a dielectric film (37) on an exposed surface of the patterned first and second conductive films; and forming a third conductive film (38) so as to surround the patterned first and second conductive films around which the dielectric film is formed.

Claim 42

A method of producing a dynamic random access memory device as claimed in anyone of claims 30 to 32, characterized in that the the first conductive film (36₁) is formed directly on the first film.

Claim 43

A method of producing a dynamic random access memory device as claimed in anyone of claims 30 to 33, characterized in that in the patterning step, the first and second conductive films (36a₁, 36a₂) are patterned by the same resist film.

Claim 44

A method of producing a dynamic random access memory device as claimed in anyone of claims 30 to 33, characterized in that in the patterning step, the first and second conductive films are patterned by different resist films.

Claim 45

A method of producing a dynamic random access memory device comprising the step of forming a transfer transistor (T) comprising a pair of impurity diffused regions (13, 14) which are located within an area defined by a field insulating film (12) formed on a substrate (11), and a gate electrode (WL1) being located between the pair of impurity diffused regions; characterized in that the method comprises the steps of forming a first film (15) so as to cover the transfer transistor for insulation; forming a first opening (23₇) in the first film, either one of the impurity diffused regions being exposed through the opening; forming a first conductive film (46a₁) on the first film and in the first opening; forming a second film (42a₁) on the first conductive film, the second film being made of a material different from the first film; forming a second opening (23₈) in the second film above said one of the impurity diffused regions, the first conductive film being exposed through the opening; forming a second conductive film (46a₂) on the first conductive film and in the second opening; patterning the first and second conductive films (46a₁, 46a₂) and the second film in accordance with a desired size of a storage electrode; selectively removing a remaining portion of the second film by isotropic etching; forming a dielectric film (47a) on an exposed surface of the patterned first and second conductive films; and forming a third conductive film (48a) so as to surround the patterned first and second conductive films around which the dielectric film is formed.

Claim 46

A method of producing a dynamic random access memory device comprising the step of forming a transfer transistor (T) comprising a pair of impurity diffused regions (13, 14) which are located within an area defined by a field insulating film (12) formed on a substrate (11), and a gate electrode (WL1) being located between the pair of impurity diffused regions; characterized in that the method comprises the steps of forming a first film (15) so as to cover the transfer transistor for insulation; forming a first opening (23₇) in the first film, either one of the impurity diffused regions being exposed through the opening; forming a first conductive film (46a₁) on the first film and in the first opening; forming a second film (42a₁) on the first conductive film, the second film being made of a material different from the first film; forming a second opening (23₈) in the second film above said one of the impurity diffused regions, the first conductive film being exposed through the opening; forming a second conductive film (46a₂) on the first conductive film and in the second opening; patterning the first and second conductive films (46a₁, 46a₂) and the second film in accordance with a desired size of a storage electrode; selectively removing a remaining portion of the second film by isotropic etching; forming a dielectric film (47a) on an exposed surface of the patterned first and second conductive films; and forming a third conductive film (48a) so as to surround the patterned first and second conductive films around which the dielectric film is formed.

Claim 49

A method of producing a dynamic random access memory device as claimed in anyone of claims 36 to 38, characterized in that the the first conductive film (46a₁) is formed directly on the first film.

Claim 50

A method of producing a dynamic random access memory device as claimed in anyone of claims 36 to 39, characterized in that in the patterning step, the first and second conductive films are patterned by the same resist film.

Claim 51

A method of producing a dynamic random access memory device as claimed in anyone of claims 36 to 39, characterized in that in the patterning step, the first and second conductive films (46a₁, 46a₂) are patterned by different resist films.

Claim 52

A method of producing a dynamic random access memory device comprising the step of forming a transfer transistor (T) comprising a pair of impurity diffused regions (13, 14) which are located within an area defined by a field insulating film (12) formed on a substrate (11), and a gate electrode (WL1) being located between the pair of impurity diffused regions; characterized in that the method comprises the steps of forming a first film (15) so as to cover the transfer transistor for insulation; forming a second film (122) on the first film, the second film being made of a material different from the first film; forming a first conductive film (226) on the second film; forming a first opening (123₁) wider than one of the impurity diffused regions in the first conductive film and a second opening (123₂) in the first and and second films, either one of the first and second the impurity diffused regions being exposed through the first opening; depositing a second conductive film (326) on the first conductive film, the second film and in the second opening; patterning the first and second conductive films (226, 326) in accordance with a desired size of a storage electrode, so that a storage electrode having a stepped part on an end thereof is formed by the patterned first and second conductive films; selectively removing the second film (122) by isotropic etching; forming a dielectric film (127) on an exposed surface of the patterned first and second conductive films; and forming a third conductive film (128) so as to surround the patterned first and second conductive films around which the dielectric film is formed.

Claim 53

A method of producing a dynamic random access memory device comprising the step of forming a transfer transistor (T) comprising a pair of impurity diffused regions (13, 14) which are located within an area defined by a field insulating film (12) formed on a substrate (11), and a gate electrode (WL1) being located between the pair of impurity diffused regions; characterized in that the method comprises the steps of forming a first film (15) so as to cover the transfer transistor for insulation; forming a second film (122) on the first film, the second film being made of a material different from the first film; forming a first conductive film (226) on the second film; forming a first opening (123₁) wider than one of the impurity diffused regions in the first conductive film and a second opening (123₂) in the first and and second films, either one of the first and second the impurity diffused regions being exposed through the first opening; depositing a second conductive film (326) on the first conductive film, the second film and in the second opening; patterning the first and second conductive films (226, 326) in accordance with a desired size of a storage electrode, so that a storage electrode having a stepped part on an end thereof is formed by the patterned first and second conductive films; selectively removing the second film (122) by isotropic etching; forming a dielectric film (127) on an exposed surface of the patterned first and second conductive films; and forming a third conductive film (128) so as to surround the patterned first and second conductive films around which the dielectric film is formed.

Claim 56

A method of producing a dynamic random access memory device comprising the step of forming a transfer transistor (T) comprising a pair of impurity diffused regions (13, 14) which are located within an area defined by a field insulating film (12) formed on a substrate, and a gate electrode (WL1) being located between the pair of impurity diffused regions; characterized in that the method comprises the steps of forming a first film (15) so as to cover the transfer transistor for insulation; forming a first conductive film (236a) on the first film and the first film; forming an opening (133a₁) in the first conductive film; forming a second conductive film (336a₁) on the first conductive film and the first film; forming a second film (132a₂) on the second conductive film, the second film being made of a material different from the first film; forming a second opening (133a₂) which penetrates the first film, the second conductive film and the second film, so that either one (13) of the impurity diffused regions is exposed through the second opening; forming a third conductive film (336a₂) on the second film, an inner wall of the second opening and the exposed impurity diffused region; patterning the first, second and third conductive films (236, 336a₁, 336a₂) and the second film in accordance with a desired size of a storage electrode; selectively removing a remaining portion of the second film 132a₂ by isotropic etching; forming a dielectric film (137a) on an exposed surface of the patterned first, second and third conductive films; and forming a fourth conductive film (138a) so as to surround the patterned first, second and third conductive films around which the dielectric film is formed.

Claim 57

A method of producing a dynamic random access memory device comprising the step of forming a transfer transistor (T) comprising a pair of impurity diffused regions (13, 14) which are located within an area defined by a field insulating film (12) formed on a substrate, and a gate electrode (WL1) being located between the pair of impurity diffused regions; characterized in that the method comprises the steps of forming a first film (15) so as to cover the transfer transistor for insulation; forming a first conductive film (236a) on the first film and the first film; forming an opening (133a₁) in the first conductive film; forming a second conductive film (336a₁) on the first conductive film and the first film; forming a second film (132a₂) on the second conductive film, the second film being made of a material different from the first film; forming a second opening (133a₂) which penetrates the first film, the second conductive film and the second film, so that either one (13) of the impurity diffused regions is exposed through the second opening; forming a third conductive film (336a₂) on the second film, an inner wall of the second opening and the exposed impurity diffused region; patterning the first, second and third conductive films (236, 336a₁, 336a₂) and the second film in accordance with a desired size of a storage electrode; selectively removing a remaining portion of the second film 132a₂ by isotropic etching; forming a dielectric film (137a) on an exposed surface of the patterned first, second and third conductive films; and forming a fourth conductive film (138a) so as to surround the patterned first, second and third conductive films around which the dielectric film is formed.

Claim 60

A method of producing a dynamic random access memory device as claimed in anyone of claims 45 to 47, characterized in that the the first conductive film (236a) is formed directly on the first film.

Claim 61

A method of producing a dynamic random access memory device as claimed in claims 45 to 48, characterized in that in the patterning step, the first, second and third conductive films (236a, 336a₁, 336a₂) are patterned by the same resist film.

Claim 62

A method of producing a dynamic random access memory device as claimed in anyone of claims 45 to 48, characterized in that in the patterning step, the first and second conductive films (236a, 336a₁) are patterned by a resist film different from that for the third conductive film (336a₂).

Claim 63

A method of producing a dynamic random access memory device comprising the step of forming a transfer transistor (T) comprising a pair of impurity diffused regions which are located within an area defined by a field insulating film (12) formed on a substrate, and a gate electrode (WL1) being located between the pair of impurity diffused regions; characterized in that the method comprises the steps of forming a first film (15) so as to cover the transfer transistor for insulation; forming a first conductive film (246a) on the first film; opening a first opening (153₁) wider than one of the impurity diffused regions in the first conductive film; forming a second opening (153₂) in the first film, either one of the impurity diffused regions being exposed through the second opening; forming a second conductive film (346a₁) on the first conductive film, the first film and in the second opening; forming a second film (142a₂) on the second conductive film, the second film being made of a material different from the first film; forming a third opening (153₃) in the second film above said one of the impurity diffused regions; forming a third conductive film (346a₂) on the second conductive film and in the third opening; patterning the first, second and third conductive films (246a, 346a₁, 346a₂) and the second film (142a₂) in accordance with a desired size of a storage electrode; selectively removing a remaining portion of the second film (142a₂) by isotropic etching; forming a dielectric film (147a) on an exposed surface of the patterned first, second and third conductive films; and forming a fourth conductive film (148a) so as to surround the patterned first, second and third conductive films around which the dielectric film is formed.

Claim 64

A method of producing a dynamic random access memory device comprising the step of forming a transfer transistor (T) comprising a pair of impurity diffused regions which are located within an area defined by a field insulating film (12) formed on a substrate, and a gate electrode (WL1) being located between the pair of impurity diffused regions; characterized in that the method comprises the steps of forming a first film (15) so as to cover the transfer transistor for insulation; forming a first conductive film (246a) on the first film; opening a first opening (153₁) wider than one of the impurity diffused regions in the first conductive film; forming a second opening (153₂) in the first film, either one of the impurity diffused regions being exposed through the second opening; forming a second conductive film (346a₁) on the first conductive film, the first film and in the second opening; forming a second film (142a₂) on the second conductive film, the second film being made of a material different from the first film; forming a third opening (153₃) in the second film above said one of the impurity diffused regions; forming a third conductive film (346a₂) on the second conductive film and in the third opening; patterning the first, second and third conductive films (246a, 346a₁, 346a₂) and the second film (142a₂) in accordance with a desired size of a storage electrode; selectively removing a remaining portion of the second film (142a₂) by isotropic etching; forming a dielectric film (147a) on an exposed surface of the patterned first, second and third conductive films; and forming a fourth conductive film (148a) so as to surround the patterned first, second and third conductive films around which the dielectric film is formed.

Claim 67

A method of producing a dynamic random access memory device as claimed in anyone of claims 51 to 53, characterized in that the the first conductive film (246a) is formed directly on the first film.

Claim 68

A method of producing a dynamic random access memory device as claimed in anyone of claims 51 to 54, characterized in that in the patterning step, the first, second and third conductive films (246a, 346a₁, 346a₂) are patterned by the same resist film.

Claim 69

A method of producing a dynamic random access memory device as claimed in anyone of claims 51 to 54, characterized in that in the patterning step, the first and second conductive films (246a, 346a₁) are patterned by a resist film which is different from that for the third conductive film (346a₂).