JP2006310578A - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To mount a capacitive element constituted of polycrystalline silicon on the same substrate together with a high breakdown voltage transistor, while contriving the simplification of the manufacturing process therefor. <P>SOLUTION: After forming a gate insulating film 7 on a high breakdown voltage transistor forming region R1 of the semiconductor substrate 1 by effecting the thermal oxidation of surface of the semiconductor substrate 1 employing an oxidation preventing film 6 as a mask, an oxidation preventing film 6 on the low breakdown voltage transistor forming region R2 is removed and, further, the thermal oxidation of surface of the semiconductor substrate 1 is effected employing the oxidation preventing film 6 as the mask. Accordingly, a gate insulating film 7 on a high breakdown voltage transistor forming region R1 is thickened and a gate insulating film 8 is formed on the semiconductor substrate 1 in the low breakdown voltage transistor forming region R2 while forming an upper electrode 9c, arranged through the oxidation preventing film 6, in one region on the lower electrode 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device, and is particularly suitable for application to a semiconductor device in which a capacitor element made of polycrystalline silicon and a high voltage transistor are mixed.

  In a conventional semiconductor device, there is a method of mounting capacitive elements each having an upper electrode and a lower electrode made of polycrystalline silicon on a semiconductor substrate on which a high breakdown voltage transistor is formed. Here, when the gate insulating film of the high breakdown voltage transistor is formed by thermal oxidation of the semiconductor substrate, in order to prevent the polycrystalline silicon constituting the lower electrode of the capacitive element from disappearing due to thermal oxidation, The semiconductor substrate is selectively oxidized after the polycrystalline silicon constituting the electrode is covered with a silicon nitride film.

Further, for example, in Patent Document 1, when a split gate type memory transistor, a capacitive element, and another capacitive element are mixedly mounted on the same chip, the capacitance values of the capacitive element and the other capacitive element can be adjusted to desired values, respectively. Therefore, the dielectric film of the capacitive element is composed of a thermal oxide film, a silicon nitride film and a thermal oxide film, and the dielectric film of the other capacitive element is a CVD silicon oxide film, a thermal oxide film, and a silicon nitride film. And a method of forming with a thermal oxide film is disclosed.
JP 2000-353796 A

However, in the conventional semiconductor device, the silicon nitride film used as the dielectric film of the capacitive element mixed with the high breakdown voltage transistor is used to form the gate insulating film of the high breakdown voltage transistor by selective oxidation. And are formed separately, there is a problem that the manufacturing process becomes long.
Further, Patent Document 1 discloses that when a gate insulating film of a high breakdown voltage transistor is formed by selective oxidation of a semiconductor substrate, a silicon nitride film used for the selective oxidation is used as a dielectric of a capacitive element mixed with the high breakdown voltage transistor. No method for use as a membrane is disclosed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor device and a semiconductor device capable of mixing a capacitive element and a high breakdown voltage transistor formed using polycrystalline silicon on the same substrate while simplifying the manufacturing process. It is to provide a manufacturing method.

In order to solve the above-described problem, according to a semiconductor device of one embodiment of the present invention, a thermal oxide film formed by selective oxidation of a semiconductor substrate, and a field effect type having the thermal oxide film as a gate insulating film It is characterized by comprising a transistor and a capacitor element that is disposed on the semiconductor substrate and has an antioxidant film as a dielectric film used for the selective oxidation.
As a result, it is possible to increase the thickness of the gate insulating film of the field effect transistor while preventing the electrode of the capacitive element from being oxidized, and the oxidation for forming the gate insulating film by selective oxidation. It is not necessary to form a dielectric film for the capacitor element separately from the prevention film. For this reason, it is possible to mount the high voltage transistor and the capacitor on the same substrate while simplifying the manufacturing process.

  In addition, according to the semiconductor device of one embodiment of the present invention, the first thermal oxide film formed by selective oxidation of the semiconductor substrate, the high breakdown voltage transistor having the first thermal oxide film as a gate insulating film, A second thermal oxide film formed by thermal oxidation of a semiconductor substrate, a low breakdown voltage transistor having the second thermal oxide film as a gate insulating film, and an anti-oxidation disposed on the semiconductor substrate and used for the selective oxidation And a capacitor having a film as a dielectric film.

  This makes it possible to form gate insulating films having different thicknesses on the same substrate while preventing the electrodes of the capacitor elements from being oxidized, and to form the gate insulating film by selective oxidation. It is not necessary to form the dielectric film of the capacitor element separately from the antioxidant film. For this reason, it is possible to mount the low breakdown voltage transistor, the high breakdown voltage transistor and the capacitor on the same substrate while simplifying the manufacturing process.

  According to the semiconductor device of one embodiment of the present invention, the insulating film formed on the semiconductor substrate, the lower polycrystalline silicon layer formed on the insulating film, and the selective oxidation of the semiconductor substrate. A gate insulating film formed on the semiconductor substrate, a gate electrode formed on the gate insulating film, a source / drain layer formed on the semiconductor substrate so as to sandwich the gate electrode, and a lower polycrystalline silicon layer And an antioxidant film used for the selective oxidation, and an upper polycrystalline silicon layer formed on the lower polycrystalline silicon layer via the antioxidant film.

  This makes it possible to increase the thickness of the gate insulating film while preventing the electrode of the capacitive element from disappearing even when a polycrystalline silicon layer is used as the electrode of the capacitive element. Can be used both as an antioxidant film for forming the film by selective oxidation and a dielectric film of the capacitor element. Therefore, it is not necessary to form the dielectric film of the capacitor element separately from the antioxidant film for forming the gate insulating film by selective oxidation, and the high breakdown voltage transistor and the capacitor element can be simplified while simplifying the manufacturing process. Can be mixed and mounted on the same substrate.

  In addition, according to the semiconductor device of one embodiment of the present invention, an insulating film formed in a partial region on the semiconductor substrate, a lower polycrystalline silicon layer formed on the insulating film, and the semiconductor substrate A first gate insulating film formed by selective oxidation, a first gate electrode formed on the first gate insulating film, and a first gate formed on the semiconductor substrate so as to sandwich the first gate electrode. A source / drain layer, a second gate insulating film formed by thermal oxidation of the semiconductor substrate, a second gate electrode formed on the second gate insulating film, and the second gate electrode are sandwiched therebetween. A second source / drain layer formed on the semiconductor substrate, an antioxidant film disposed on the lower polycrystalline silicon layer and used for the selective oxidation, and the lower polycrystalline layer through the antioxidant film Shape on silicon layer Characterized in that it comprises a by upper layer polycrystalline silicon layer.

  Thereby, even when a polycrystalline silicon layer is used as an electrode of a capacitor element, it is possible to form gate insulating films having different film thicknesses on the same substrate while preventing the electrode of the capacitor element from disappearing. In addition, the antioxidant film for forming the gate insulating film by selective oxidation and the dielectric film of the capacitor element can be used together. For this reason, it is not necessary to form a dielectric film for the capacitor element separately from the anti-oxidation film for forming the gate insulating film by selective oxidation, and the low breakdown voltage transistor and the high breakdown voltage are reduced while simplifying the manufacturing process. It becomes possible to mount the transistor and the capacitor on the same substrate.

  According to the method for manufacturing a semiconductor device of one embodiment of the present invention, a step of forming an insulating film in a partial region on the semiconductor substrate, and a step of forming a lower polycrystalline silicon layer on the insulating film; Forming an antioxidant film covering the lower polycrystalline silicon layer on the semiconductor substrate; removing the antioxidant film from a partial region on the semiconductor substrate; and masking the antioxidant film A step of selectively oxidizing the semiconductor substrate to form a gate insulating film on the semiconductor substrate, and an upper polycrystalline silicon layer disposed via the antioxidant film on the lower polycrystalline silicon layer. Forming a gate electrode disposed on the gate insulating film, and forming a source / drain layer disposed so as to sandwich the gate electrode on the semiconductor substrate. Characterized in that it obtain.

As a result, the anti-oxidation film for forming the gate insulating film by selective oxidation and the dielectric film of the capacitor element can be used together, and the high breakdown voltage transistor and the capacitor element can be formed while simplifying the manufacturing process. It becomes possible to mount them on the same substrate.
According to the method for manufacturing a semiconductor device of one embodiment of the present invention, a step of forming an insulating film in a partial region on the semiconductor substrate, and a step of forming a lower polycrystalline silicon layer on the insulating film; Forming an antioxidant film covering the lower polycrystalline silicon layer on the semiconductor substrate; removing the antioxidant film from a partial region on the semiconductor substrate; and masking the antioxidant film Performing a selective oxidation of the surface of the semiconductor substrate to form a first gate insulating film on the semiconductor substrate, and removing a portion of the antioxidant film from a partial region on the semiconductor substrate. A step of forming a second gate insulating film on the semiconductor substrate by performing thermal oxidation of the surface of the semiconductor substrate from which the antioxidant film has been removed, and being disposed via the antioxidant film Upper layer polycrystalline silicon Forming first and second gate electrodes respectively disposed on the first and second gate insulating films, and forming the first and second gates on the lower polycrystalline silicon layer; Forming first and second source / drain layers arranged so as to sandwich the electrodes, respectively, on the semiconductor substrate.

  As a result, the anti-oxidation film for forming the gate insulating film by selective oxidation and the dielectric film of the capacitive element can be used together, and the low-breakdown voltage transistor and the high-breakdown voltage transistor can be simplified while simplifying the manufacturing process. Capacitance elements can be mixed on the same substrate.

Hereinafter, a semiconductor device and a manufacturing method thereof according to embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a method for manufacturing a semiconductor device according to an embodiment of the present invention.
In FIG. 1A, a semiconductor substrate 1 is provided with a high breakdown voltage transistor formation region R1, a low breakdown voltage transistor formation region R2, and a capacitor element formation region R3. Then, for example, by using a method such as LOCOS (Local Oxidation of Silicon) method, the high breakdown voltage transistor formation region R1 and the low breakdown voltage transistor formation region R2 are isolated, and the element isolation insulation corresponding to the capacitive element formation region R3 A film 2 is formed on the semiconductor substrate 1. In addition, as a method for forming the element isolation insulating film 2 on the semiconductor substrate 1, an STI (Shallow Trench Isolation) method may be used. Then, a sacrificial oxide film 3 is formed on the semiconductor substrate 1 by thermally oxidizing the surface of the semiconductor substrate 1.

  Next, as shown in FIG. 1B, a polycrystalline silicon film is formed on the entire surface of the semiconductor substrate 1 by using a method such as CVD. The film thickness of the polycrystalline silicon film can be set to about 1700 mm, for example. Then, the lower electrode 4 is formed on the element isolation insulating film 2 in the capacitive element formation region R3 by patterning the polycrystalline silicon film using a photolithography technique and an etching technique. Then, the surface of the lower electrode 4 is thermally oxidized to form an oxide film 5 on the surface of the lower electrode 4. The film thickness of the oxide film 5 can be about 120 mm, for example.

Next, as shown in FIG. 1C, an antioxidant film 6 is formed on the entire surface of the semiconductor substrate 1 by using a method such as CVD. For example, a silicon nitride film can be used as the antioxidant film 6. Further, the film thickness of the antioxidant film 6 can be set to, for example, about 150 mm.
Next, as shown in FIG. 1D, the antioxidant film 6 is patterned by using a photolithography technique and an etching technique, so that the low breakdown voltage transistor forming region R2 and the capacitor element forming region R3 are formed into the antioxidant film 6. Then, the antioxidant film 6 in the high breakdown voltage transistor formation region R1 is removed.

  Next, as shown in FIG. 1E, after the sacrificial oxide film 3 in the high breakdown voltage transistor formation region R1 is removed by a method such as wet etching, the surface of the semiconductor substrate 1 is thermally oxidized using the antioxidant film 6 as a mask. As a result, a gate insulating film 7 is formed on the semiconductor substrate 1 in the high breakdown voltage transistor formation region R1. The film thickness of the gate insulating film 7 can be about 97 mm, for example. Here, by performing thermal oxidation while covering the low breakdown voltage transistor formation region R2 and the capacitive element formation region R3 with the antioxidant film 6, the semiconductor substrate 1 in the low breakdown voltage transistor formation region R2 and the lower portion of the capacitive element formation region R3 It is possible to prevent the electrode 4 from being thermally oxidized.

Next, as shown in FIG. 1F, a photoresist F that covers the high breakdown voltage transistor formation region R1 and the capacitive element formation region R3 and exposes the low breakdown voltage transistor formation region R2 by using a photolithography technique. Form.
Next, as shown in FIG. 2A, the antioxidant film 6 and the sacrificial oxide film 3 are etched using the photoresist F as a mask, so that the capacitor element formation region R3 is covered with the antioxidant film 6. Then, the antioxidant film 6 and the sacrificial oxide film 3 in the low breakdown voltage transistor formation region R2 are removed.

  Next, as shown in FIG. 2B, the photoresist F on the semiconductor substrate 1 is removed. Then, by performing thermal oxidation of the surface of the semiconductor substrate 1 using the antioxidant film 6 as a mask, the gate insulating film 7 in the high breakdown voltage transistor formation region R1 is thickened and the semiconductor substrate 1 in the low breakdown voltage transistor formation region R2 is formed. A gate insulating film 8 is formed thereon. The film thickness of the gate insulating film 8 can be about 97 mm, for example. Here, by performing thermal oxidation while covering the capacitive element formation region R3 with the antioxidant film 6, it is possible to prevent the lower electrode 4 of the capacitive element formation region R3 from being thermally oxidized.

  Next, as shown in FIG. 2C, a polycrystalline silicon film is formed on the entire surface of the semiconductor substrate 1 by using a method such as CVD. Then, by patterning the polycrystalline silicon film using a photolithography technique and an etching technique, gate electrodes 9a and 9b are formed in the high breakdown voltage transistor formation region R1 and the low breakdown voltage transistor formation region R2, and the antioxidant film 6 is formed. The upper electrode 9 c disposed therebetween is formed in a partial region on the lower electrode 4.

  Next, as shown in FIG. 2D, impurity ion implantation is performed on the semiconductor substrate 1 using the gate electrodes 9a and 9b as masks, whereby a source / drain layer 10a disposed so as to sandwich the gate electrode 9a, 11a is formed in the high breakdown voltage transistor formation region R1, and source / drain layers 10b and 11b arranged so as to sandwich the gate electrode 9b are formed in the low breakdown voltage transistor formation region R2.

  Next, as shown in FIG. 2E, an interlayer insulating film 12 is formed on the entire surface of the semiconductor substrate 1 by using a method such as CVD. Then, by patterning the interlayer insulating film 12 using a photolithography technique and an etching technique, the openings 12a to expose the surfaces of the source / drain layers 10a, 11a, 10b, 11b, the upper electrode 9c, and the lower electrode 4, respectively. 12 f is formed in the interlayer insulating film 12. Then, wiring layers 13a to 13f connected to the source / drain layers 10a, 11a, 10b, and 11b, the upper electrode 9c, and the lower electrode 4 through the openings 12a to 12f are formed on the interlayer insulating film 12.

  Thereby, even when a polycrystalline silicon film is used as the lower electrode 4 and the upper electrode 9c, the gate insulating films 7 and 8 having different thicknesses can be formed while preventing the lower electrode 4 from disappearing due to thermal oxidation. In addition to being able to be formed on the same semiconductor substrate 1, the antioxidant film 6 for forming the gate insulating film 7 by selective oxidation can also be used as the dielectric film of the capacitive element. For this reason, it is not necessary to form a dielectric film of the capacitive element separately from the antioxidant film 6 for forming the gate insulating film 7 by selective oxidation, and the low breakdown voltage transistor and the It becomes possible to mount the high breakdown voltage transistor and the capacitor on the same semiconductor substrate 1.

  In the above-described embodiment, the method of mounting the low breakdown voltage transistor and the high breakdown voltage transistor and the capacitive element on the same semiconductor substrate 1 has been described. However, the high breakdown voltage transistor and the capacitive element are mounted on the same semiconductor substrate 1. The present invention may be applied to a method, or may be applied to a method in which a low breakdown voltage transistor, a medium breakdown voltage transistor, a high breakdown voltage transistor, and a capacitor are mixedly mounted on the same semiconductor substrate 1.

Sectional drawing which shows the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention. Sectional drawing which shows the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Semiconductor substrate, 2 Element isolation insulating film, 3 Sacrificial oxide film, 4 Lower electrode, 5 Oxide film, 6 Antioxidation film, 7, 8 Gate insulating film, 9a, 9b Gate electrode, 9c Upper electrode, 10a, 10b Source layer 11a, 11b Drain layer, 12 interlayer insulating film, 12a-12f opening, 13a-13f wiring layer, F photoresist, R1 high breakdown voltage transistor formation region, R2 low breakdown voltage transistor formation region, R3 capacitor element formation region

Claims (6)

A thermal oxide film formed by selective oxidation of a semiconductor substrate;
A field effect transistor having the thermal oxide film as a gate insulating film;
A semiconductor device comprising: a capacitor element disposed on the semiconductor substrate and having an anti-oxidation film used for the selective oxidation as a dielectric film. A first thermal oxide film formed by selective oxidation of a semiconductor substrate;
A high breakdown voltage transistor having the first thermal oxide film as a gate insulating film;
A second thermal oxide film formed by thermal oxidation of the semiconductor substrate;
A low breakdown voltage transistor having the second thermal oxide film as a gate insulating film;
A semiconductor device comprising: a capacitor element disposed on the semiconductor substrate and having an anti-oxidation film used for the selective oxidation as a dielectric film. An insulating film formed on the semiconductor substrate;
A lower polycrystalline silicon layer formed on the insulating film;
A gate insulating film formed by selective oxidation of the semiconductor substrate;
A gate electrode formed on the gate insulating film;
A source / drain layer formed on the semiconductor substrate so as to sandwich the gate electrode;
An antioxidant film disposed on the lower polycrystalline silicon layer and used for the selective oxidation;
A semiconductor device comprising: an upper polycrystalline silicon layer formed on the lower polycrystalline silicon layer through the antioxidant film. An insulating film formed in a partial region on the semiconductor substrate;
A lower polycrystalline silicon layer formed on the insulating film;
A first gate insulating film formed by selective oxidation of the semiconductor substrate;
A first gate electrode formed on the first gate insulating film;
A first source / drain layer formed on the semiconductor substrate so as to sandwich the first gate electrode;
A second gate insulating film formed by thermal oxidation of the semiconductor substrate;
A second gate electrode formed on the second gate insulating film;
A second source / drain layer formed on the semiconductor substrate so as to sandwich the second gate electrode;
An antioxidant film disposed on the lower polycrystalline silicon layer and used for the selective oxidation;
A semiconductor device comprising: an upper polycrystalline silicon layer formed on the lower polycrystalline silicon layer through the antioxidant film. Forming an insulating film in a partial region on the semiconductor substrate;
Forming a lower polycrystalline silicon layer on the insulating film;
Forming an anti-oxidation film covering the lower polycrystalline silicon layer on the semiconductor substrate;
Removing the antioxidant film from a partial region on the semiconductor substrate;
Forming a gate insulating film on the semiconductor substrate by performing selective oxidation of the semiconductor substrate using the antioxidant film as a mask;
Forming an upper polycrystalline silicon layer disposed via the antioxidant film on the lower polycrystalline silicon layer and forming a gate electrode disposed on the gate insulating film;
Forming a source / drain layer on the semiconductor substrate so as to sandwich the gate electrode. A method for manufacturing a semiconductor device, comprising: Forming an insulating film in a partial region on the semiconductor substrate;
Forming a lower polycrystalline silicon layer on the insulating film;
Forming an anti-oxidation film covering the lower polycrystalline silicon layer on the semiconductor substrate;
Removing the antioxidant film from a partial region on the semiconductor substrate;
Forming a first gate insulating film on the semiconductor substrate by performing selective oxidation of the surface of the semiconductor substrate using the antioxidant film as a mask;
Removing a portion of the antioxidant film from a partial region on the semiconductor substrate;
Forming a second gate insulating film on the semiconductor substrate by thermally oxidizing the surface of the semiconductor substrate from which the antioxidant film has been removed;
Forming an upper polycrystalline silicon layer disposed through the antioxidant film on the lower polycrystalline silicon layer, and first and second gate electrodes respectively disposed on the first and second gate insulating films; Forming a step;
Forming a first and second source / drain layer on the semiconductor substrate so as to sandwich the first and second gate electrodes, respectively.

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