阅读说明：本技术 半导体装置及其形成方法 (Semiconductor device and method of forming the same ) 是由 迫川泰幸 于 2021-05-14 设计创作，主要内容包括：本申请涉及一种半导体装置及其形成方法。一种半导体装置包括半导体衬底；以及所述半导体衬底上的多层布线结构,所述多层布线结构包括第一绝缘层、所述第一绝缘层上的第一导电层、所述第一绝缘层上的第二导电层、所述第一和第二导电层上的第三导电层、所述第三导电层上的第四导电层和所述第四导电层上的第二绝缘层。所述多层布线结构包括：第一栅电极,其包含分别在所述第一和第二绝缘层中的第一和第二绝缘膜,以及分别在所述第一、第三和第四导电层中的第一、第三和第四导电膜；以及第二栅电极,其包含分别在所述第一和第二绝缘层中的第一和第二绝缘膜,以及分别在所述第二、第三和第四导电层中的第二、第三和第四导电膜。(The present application relates to a semiconductor device and a method of forming the same. A semiconductor device includes a semiconductor substrate; and a multilayer wiring structure on the semiconductor substrate, the multilayer wiring structure including a first insulating layer, a first conductive layer on the first insulating layer, a second conductive layer on the first insulating layer, a third conductive layer on the first and second conductive layers, a fourth conductive layer on the third conductive layer, and a second insulating layer on the fourth conductive layer. The multilayer wiring structure includes: a first gate electrode including first and second insulating films in the first and second insulating layers, respectively, and first, third, and fourth conductive films in the first, third, and fourth conductive layers, respectively; and a second gate electrode including first and second insulating films in the first and second insulating layers, respectively, and second, third, and fourth conductive films in the second, third, and fourth conductive layers, respectively.)

1. A semiconductor device, comprising:

a semiconductor substrate; and

a multilayer wiring structure on the semiconductor substrate, the multilayer wiring structure including a first insulating layer, a first conductive layer on the first insulating layer, a second conductive layer on the first insulating layer, a third conductive layer on the first and second conductive layers, a fourth conductive layer on the third conductive layer, and a second insulating layer on the fourth conductive layer,

wherein the multilayer wiring structure includes:

a first gate electrode including first and second insulating films in the first and second insulating layers, respectively, and first, third, and fourth conductive films in the first, third, and fourth conductive layers, respectively; and

a second gate electrode including first and second insulating films in the first and second insulating layers, respectively, and second, third, and fourth conductive films in the second, third, and fourth conductive layers, respectively.

2. The semiconductor device according to claim 1, wherein the third conductive film included in the first gate electrode and the third conductive film included in the second gate electrode comprise a first material, and wherein the fourth conductive film included in the first gate electrode and the fourth conductive film included in the second gate electrode comprise a second material.

3. The semiconductor device according to claim 1, wherein the third conductive film included in the first gate electrode and the third conductive film included in the second gate electrode are formed in the same process step, and wherein the fourth conductive film included in the first gate electrode and the fourth conductive film included in the second gate electrode are formed in the same process step.

4. The semiconductor device according to claim 1, wherein the first conductive film included in the first gate electrode and the second conductive film included in the second gate electrode have different work functions.

5. The semiconductor device according to claim 1, wherein the first conductive film included in the first gate electrode and the second conductive film included in the second gate electrode are formed in different process steps.

6. The semiconductor device according to claim 1, wherein the first conductive film included in the first gate electrode and the second conductive film included in the second gate electrode comprise titanium nitride.

7. The semiconductor device according to claim 6, wherein a composition ratio of titanium to nitrogen in titanium nitride included in the first conductive film is different from a composition ratio of titanium to nitrogen in titanium nitride included in the second conductive film.

8. The semiconductor device according to claim 1, wherein the semiconductor substrate comprises a first well of a first conductivity type and a second well of a second conductivity type, the first gate electrode being provided over the first well, the second gate electrode being provided over the second well.

9. The semiconductor device of claim 1, further comprising:

a third gate electrode connecting the first gate electrode and the second gate electrode,

wherein the third gate electrode includes the third conductive film and the fourth conductive film.

10. The semiconductor device according to claim 1, wherein the first insulating film comprises a high-k material.

11. A method of fabricating a semiconductor device, comprising:

forming a first conductive-type first well and a second conductive-type second well having a distance therebetween;

forming a first insulating film, a first conductive film, and a first cover insulating film in this order to cover each of the first and second wells;

etching the first cover insulating film and the first conductive film to leave first portions of the first cover insulating film and the first conductive film on the first well and expose the first insulating film on the second well;

forming a second conductive film and a second cover insulating film in this order to cover the first insulating film over the second well and the first portion over the first well; and

the second conductive film and the second cover insulating film are etched to leave second portions of the second conductive film and the second cover insulating film on the second well and to expose the first portions on the first well.

12. The method of claim 11, wherein the first conductive film and the second conductive film have different work functions.

13. The method of claim 11, wherein the first and second conductive films comprise titanium nitride.

14. The method according to claim 13, wherein a composition ratio of titanium to nitrogen in titanium nitride included in the first conductive film is different from a composition ratio of titanium to nitrogen in titanium nitride included in the second conductive film.

15. The method of claim 11, further comprising:

removing the first insulating film except for the first portion and the second portion;

forming a third conductive film, a fourth conductive film, and a second insulating film to cover the first portion and the second portion; and

forming a first gate electrode including the first portion, the third conductive film, the fourth conductive film, and the second insulating film; and

forming a second gate electrode including the second portion, the third conductive film, the fourth conductive film, and the second insulating film.

16. The method according to claim 11, wherein the first gate electrode and the second gate electrode are connected by a third gate electrode, and wherein the third gate electrode comprises a third conductive film and a fourth conductive film.

17. A method of manufacturing a semiconductor device including a first well of a first conductivity type and a second well of a second conductivity type with a distance therebetween, the method comprising:

forming a first gate electrode including a first insulating film, a first conductive film, a third conductive film, and a fourth conductive film over the first well; and

forming a second gate electrode including a first insulating film, a second conductive film, a third conductive film, and a fourth conductive film over the second well,

wherein the first conductive film included in the first gate electrode and the second conductive film included in the second gate electrode are formed in different process steps, and

wherein the third conductive film included in the first gate electrode and the third conductive film included in the second gate electrode are formed in the same process step.

18. The method of claim 17, wherein the first conductive film and the second conductive film have different work functions.

19. The method according to claim 17, wherein a composition ratio of titanium to nitrogen in titanium nitride included in the first conductive film is different from a composition ratio of titanium to nitrogen in titanium nitride included in the second conductive film.

20. The method according to claim 17, wherein the first gate electrode and the second gate electrode are connected by a third gate electrode, and wherein the third gate electrode comprises a third conductive film and a fourth conductive film.

Technical Field

The present application relates to a semiconductor device.

Background

Semiconductor devices, such as dynamic random access memories (hereinafter referred to as "DRAMs"), are being reduced in process size and chip size to increase memory capacity and reduce device cost. Complementary metal oxide semiconductor (hereinafter referred to as "CMOS") circuits are commonly used in semiconductor devices. CMOS circuits include P-channel Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) and N-channel MOSFETs. A P-channel MOSFET is disposed on the N-well, and an N-channel MOSFET is disposed on the P-well. In order to reduce the chip size of the semiconductor device, the pitch between the P-well and the N-well, i.e., the PN isolation width, needs to be reduced.

Typically, the gate electrode of a P-channel MOSFET and the gate electrode of an N-channel MOSFET are formed in different process steps to improve the performance of the MOSFET. The gate electrode includes a laminated film including a plurality of conductive films and a plurality of insulating films, and the thickness of the laminated film is thick with respect to the width of the gate electrode. Therefore, in forming the gate electrode of some MOSFETs, when a plurality of conductive films and a plurality of insulating films of the gate electrode are formed, these films are inevitably deposited on the side faces of the gate electrode of other MOSFETs previously formed. Therefore, the subsequently formed gate electrode cannot be provided within a distance less than the total thickness of the conductive film and the insulating film from the previously formed gate electrode. Therefore, it is difficult to reduce the distance between the P-well and the N-well.

Disclosure of Invention

An aspect of the present application relates to a semiconductor device including: a semiconductor substrate; and a multilayer wiring structure on the semiconductor substrate, the multilayer wiring structure including a first insulating layer, a first conductive layer on the first insulating layer, a second conductive layer on the first insulating layer, a third conductive layer on the first and second conductive layers, a fourth conductive layer on the third conductive layer, and a second insulating layer on the fourth conductive layer, wherein the multilayer wiring structure includes: a first gate electrode including first and second insulating films in the first and second insulating layers, respectively, and first, third, and fourth conductive films in the first, third, and fourth conductive layers, respectively; and a second gate electrode including first and second insulating films in the first and second insulating layers, respectively, and second, third, and fourth conductive films in the second, third, and fourth conductive layers, respectively.

Another aspect of the present application relates to a method of manufacturing a semiconductor device, comprising: forming a first conductive-type first well and a second conductive-type second well having a distance therebetween; forming a first insulating film, a first conductive film, and a first cover insulating film in this order to cover each of the first and second wells; etching the first cover insulating film and the first conductive film to leave first portions of the first cover insulating film and the first conductive film on the first well and expose the first insulating film on the second well; forming a second conductive film and a second cover insulating film in this order to cover the first insulating film over the second well and the first portion over the first well; and etching the second conductive film and the second cover insulating film to leave second portions of the second conductive film and the second cover insulating film on the second well and expose the first portions on the first well.

Yet another aspect of the present application relates to a method of manufacturing a semiconductor device including a first well of a first conductivity type and a second well of a second conductivity type with a distance therebetween, the method comprising: forming a first gate electrode including a first insulating film, a first conductive film, a third conductive film, and a fourth conductive film over the first well; and forming a second gate electrode including a first insulating film, a second conductive film, a third conductive film, and a fourth conductive film over the second well, wherein the first conductive film included in the first gate electrode and the second conductive film included in the second gate electrode are formed in different process steps, and wherein the third conductive film included in the first gate electrode and the third conductive film included in the second gate electrode are formed in the same process step.

Drawings

Fig. 1 is a plan view showing an example of a schematic structure of a layout of a semiconductor device according to an embodiment of the present disclosure;

fig. 2 is a diagram showing a schematic structure of a semiconductor device according to an embodiment of the present disclosure, which is a vertical sectional view of the schematic structure of a portion along line a-a in fig. 1. Fig. 2 is also a diagram schematically illustrating a method of manufacturing a semiconductor device according to an embodiment of the present disclosure, which is a vertical cross-sectional view of a schematic structure of a PN boundary portion in an exemplary process step following fig. 9;

fig. 3A is a diagram showing a schematic structure of a semiconductor device and a method of manufacturing the same according to an embodiment of the present disclosure, which is a vertical sectional view of the schematic structure of a portion along line B-B in fig. 1;

fig. 3B is a diagram showing a schematic structure of a semiconductor device and a method of manufacturing the same according to an embodiment of the present disclosure, which is a vertical sectional view of the schematic structure of a portion along line C-C in fig. 1;

fig. 3C is a diagram showing a schematic structure of a semiconductor device and a manufacturing method thereof according to an embodiment of the present disclosure, which is a vertical sectional view of the schematic structure of a portion along line D-D in fig. 1;

fig. 4 is a diagram schematically illustrating a method of manufacturing a semiconductor device according to an embodiment of the present disclosure, which is a vertical cross-sectional view of a schematic structure of a PN boundary portion in an exemplary process step. Fig. 4 is a diagram showing a schematic structure of a portion along a line a-a in fig. 1;

fig. 5 is a diagram schematically illustrating a method of manufacturing a semiconductor device according to an embodiment of the present disclosure, which is a vertical cross-sectional view of a schematic structure of a PN boundary portion in an exemplary process step subsequent to fig. 4. Fig. 5 is a diagram showing a schematic structure of a portion along line a-a in fig. 1;

fig. 6 is a diagram schematically illustrating a method of manufacturing a semiconductor device according to an embodiment of the present disclosure, which is a vertical cross-sectional view of a schematic structure of a PN boundary portion in an exemplary process step subsequent to fig. 5. Fig. 6 is a diagram showing a schematic structure of a portion along line a-a in fig. 1;

fig. 7 is a diagram schematically illustrating a method of manufacturing a semiconductor device according to an embodiment of the present disclosure, which is a vertical cross-sectional view of a schematic structure of a PN boundary portion in an exemplary process step subsequent to fig. 6. Fig. 7 is a diagram showing a schematic structure of a portion along line a-a in fig. 1;

fig. 8 is a diagram schematically illustrating a method of manufacturing a semiconductor device according to an embodiment of the present disclosure, which is a vertical cross-sectional view of a schematic structure of a PN boundary portion in an exemplary process step subsequent to fig. 7. Fig. 8 is a diagram showing a schematic structure of a portion along line a-a in fig. 1; and

fig. 9 is a diagram schematically illustrating a method of manufacturing a semiconductor device according to an embodiment of the present disclosure, which is a vertical cross-sectional view of a schematic structure of a PN boundary portion in an exemplary process step and continues to fig. 8. Fig. 9 is a diagram showing a schematic structure of a portion along line a-a in fig. 1.

Detailed Description

Various embodiments of the present invention will be explained in detail below with reference to the accompanying drawings. The following detailed description refers to the accompanying drawings that show, by way of illustration, specific aspects and embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the present invention. The various embodiments disclosed herein are not necessarily mutually exclusive, as some disclosed embodiments may be combined with one or more other disclosed embodiments to form new embodiments.

An embodiment of the present disclosure will be described with reference to fig. 1 to 9. The following describes an illustrative example using a DRAM as a semiconductor device. Fig. 1 is a plan view showing a schematic structure of a layout of an isolation region 2 and a plurality of active regions 3 formed on a semiconductor substrate 1. The active region 3 is formed in the shape of an island which is rectangular in plan view. The active region 3 is surrounded by an isolation region 2. The active region 3 includes an active region 3a and an active region 3 b. Adjacent active regions 3 are separated by a predetermined distance E. In fig. 1, the gate electrode is disposed on two adjacent active regions 3a and 3 b. Fig. 1 shows the second insulating layer 24 constituting the top layer of the gate electrode. The layout in fig. 1 schematically shows an isolation region 2 and an active region 3 of a CMOS circuit provided in a semiconductor device 100. The CMOS circuit may include, for example, a data circuit for reading and writing memory cell data of the DRAM and a control circuit for controlling the data circuit.

Fig. 2, 3A, 3B, and 3C are diagrams illustrating a schematic structure of the semiconductor device 100 according to the embodiment. Fig. 2 is a vertical sectional view of a portion along line a-a in fig. 1. Fig. 3A is a vertical sectional view of a portion along line B-B in fig. 1. Fig. 3B is a vertical sectional view of a portion along line C-C in fig. 1. Fig. 3C is a vertical sectional view of a portion along line D-D in fig. 1. As shown in fig. 2, an active region 3 is defined by an isolation region 2 on a semiconductor substrate 1.

The semiconductor substrate 1 may be a silicon wafer including, for example, single crystal silicon. The isolation region 2 may comprise, for example, a shallow trench isolation structure. By etching trenches in the semiconductor substrate 1 and depositing a material such as silicon dioxide (SiO)₂) An insulating film such as a film and a silicon nitride (SiN) film to fill the trench to form the isolation region 2. The isolation region 2 serves to electrically isolate elements formed on the semiconductor substrate 1 from each other.

As shown in fig. 2, 3A, 3B, and 3C, a first well 1a and a second well 1B disposed adjacent to the first well 1a are formed in the semiconductor substrate 1. The first well 1a and the second well 1b are adjacent to each other with a predetermined distance therebetween. The first well 1a is a P-type semiconductor well doped with an impurity such as boron (B). The second well 1b is an N-type semiconductor well doped with an impurity such as phosphorus (P). In this specification, one of the first well 1a and the second well 1b may be referred to as a first conductive type well, and the other may be referred to as a second conductive type well.

The isolation region 2 is disposed between the active region 3a of the first well 1a and the active region 3b of the second well 1 b. That is, the active region 3a of the first well 1a and the active region 3b of the second well 1b are separated by the isolation region 2. The distance between the active region 3a and the active region 3b is denoted by E. Therefore, the width of the isolation region 2 separating the active region 3a and the active region 3b is E. The width of the isolation region 2, i.e., the distance E, serves as a PN isolation width for electrically isolating the active region 3a of the first well 1a and the active region 3b of the second well 1 b. The first well 1a and the second well 1b are connected together under the isolation region 2. The isolation region 2 constitutes a PN boundary portion.

As shown in fig. 2, 3A, 3B, and 3C, the semiconductor device 100 includes a multilayer wiring structure on the semiconductor substrate 1. The multilayer wiring structure includes a first insulating layer 4, a first conductive layer 10 on the first insulating layer 4, a second conductive layer 11 on the first insulating layer 4, a third conductive layer 12 on the first and second conductive layers 10, 11, a fourth conductive layer 13 on the third conductive layer 12, and a second insulating layer 24 on the fourth conductive layer 13.

The multilayer wiring structure includes a first gate electrode 6, a second gate electrode 7, and a third gate electrode 8. The first gate electrode 6 includes first and second insulating films 4a, 24a in the first and second insulating layers 4, 24, respectively. Further, the first gate electrode 6 includes first, third, and fourth conductive films 10a, 12a, 13a in the first, third, and fourth conductive layers 10, 12, 13, respectively. The second gate electrode 7 includes first and second insulating films 4a, 24a in the first and second insulating layers 4, 24, respectively. Further, the second gate electrode 7 includes second, third, and fourth conductive films 11a, 12a, 13a in the second, third, and fourth conductive layers 11, 12, 13, respectively. The third gate electrode 8 includes a second insulating film 24a in the second insulating layer 24, and third and fourth conductive films 12a, 13a in the third and fourth conductive layers 12, 13, respectively.

The first gate electrode 6 is formed on the active region 3a of the first well 1 a. The first gate electrode 6 serves as a gate electrode of the N-channel MOSFET. The second gate electrode 7 is formed on the active region 3b of the second well 1 b. The second gate electrode 7 serves as a gate electrode of the P-channel MOSFET. Fig. 2 shows a vertical cross-sectional structure in the channel width direction of the MOSFET described above. In the structure shown in fig. 2, the first gate electrode 6 and the second gate electrode 7 are connected by the third gate electrode 8.

As shown in fig. 3B, in the first gate electrode 6, a first insulating film 4a, a first conductive film 10a, a third conductive film 12a, a fourth conductive film 13a, and a second insulating film 24a are sequentially stacked on the semiconductor substrate 1. As shown in fig. 3A, in the second gate electrode 7, a first insulating film 4a, a second conductive film 11a, a third conductive film 12a, a fourth conductive film 13A, and a second insulating film 24a are sequentially stacked on the semiconductor substrate 1. As shown in fig. 3C, in the third gate electrode 8, a third conductive film 12a, a fourth conductive film 13a, and a second insulating film 24a are sequentially stacked on the isolation region 2 provided in the semiconductor substrate 1.

The first insulating layer 4 including the first insulating film 4a includes a high-k material having a high relative dielectric constant. The high-k film includes, for example, an oxide material containing a transition metal or the like. The high-k film includes an oxide material containing, for example, any one of yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), niobium (Nb), and tantalum (Ta). The first insulating layer 4 may also comprise other elements, such as silicon and nitrogen. The first insulating film 4a functions as a gate insulating film of the MOSFET.

The first conductive film 10a included in the first gate electrode 6 and the second conductive film 11a included in the second gate electrode 7 have different work functions. The first conductive film 10a and the second conductive film 11a include, for example, different materials. The first conductive film 10a and the second conductive film 11a include, for example, materials having different elemental composition ratios.

In an embodiment, the first conductive film 10a included in the first gate electrode 6 may include, for example, titanium nitride. The second conductive film 11a included in the second gate electrode 7 may include, for example, titanium nitride. In the embodiment, the first conductive film 10a and the second conductive film 11a have different composition ratios of nitrogen and titanium. Therefore, the first conductive film 10a and the second conductive film 11a have different work functions.

The work function of the first conductive film 10a is set to be suitable for an N-channel MOSFET. The work function of the second conductive film 11a is set to be suitable for a P-channel MOSFET. For example, when the threshold voltage of the MOSFET is set to 0.1 to 0.2V, the work function of the first conductive film 10a of the N-type MOSFET may be set to 4.3eV or less. Then, the work function of the second conductive film 11a of the P-type MOSFET may be set to, for example, 4.8eV or higher.

The first conductive film 10a and the second conductive film 11a are formed in different process steps. This enables independent control of the formation of the first conductive film 10a and the second conductive film 11a, so that these conductive films can have any work function. Therefore, the characteristics of the N-channel MOSFET disposed in the first well 1a and the P-channel MOSFET disposed in the second well 1b can be optimized independently. As a result, the performance of the N-channel MOSFET and the P-channel MOSFET included in the CMOS circuit can be improved.

The first gate electrode 6 and the second gate electrode 7 collectively include the first insulating film 4 a. The first insulating film 4a included in the first gate electrode 6 and the first insulating film 4a included in the second gate electrode 7 include the same material and are formed in the same process step.

The first gate electrode 6, the second gate electrode 7, and the third gate electrode 8 collectively include a third conductive film 12a, a fourth conductive film 13a, and a second insulating film 24 a. The third conductive film 12a included in the first gate electrode 6, the third conductive film 12a included in the second gate electrode 7, and the third conductive film 12a included in the third gate electrode 8 include the same material and are formed in the same process step. The fourth conductive film 13a included in the first gate electrode 6, the fourth conductive film 13a included in the second gate electrode 7, and the fourth conductive film 13a included in the third gate electrode 8 include the same material and are formed in the same process step. The second insulating film 24a included in the first gate electrode 6, the second insulating film 24a included in the second gate electrode 7, and the second insulating film 24a included in the third gate electrode 8 include the same material and are formed in the same process step.

The first gate electrode 6 and the second gate electrode 7 are separated by a distance of the sum of the thickness of the second conductive layer 11 and the thickness of a second insulating cover layer 20 described below, or more. The first gate electrode 6 and the second gate electrode 7 can be disposed closer, and the minimum distance between these gate electrodes is the sum of the thickness of the second conductive layer 11 and the thickness of the second insulating cover layer 20 described below.

A method of manufacturing the semiconductor device 100 will now be described with reference to fig. 1 to 9.

As shown in fig. 4, a first insulating layer 4, a first conductive layer 10 and a first cover insulating layer 15 are formed on a semiconductor substrate 1 on which a first well 1a and a second well 1b disposed adjacent to the first well 1a have been provided. For example, a single crystal silicon substrate may be used as the semiconductor substrate 1. The first well 1a is doped with a P-type impurity, such as boron (B). The second well 1b is doped with an N-type impurity, such as phosphorus (P). The first well 1a and the second well 1b are formed by doping these wells 1a and 1b with impurities and then heat-treating them.

An isolation region 2 and active regions 3a and 3b defined by the isolation region 2 are also provided in the semiconductor substrate 1. The isolation region 2 includes a shallow trench isolation structure in which an insulating film, such as a silicon oxide film, is deposited so as to fill a trench etched in the semiconductor substrate 1. The isolation region 2 has a width E. The active region 3a disposed in the first well 1a and the active region 3b disposed in the second well 1b are separated by an isolation region 2 by a distance E.

The first insulating layer 4 includes a high-k film. The high-k film may include, for example, an oxide material containing a transition metal or the like. The high-k film may include an oxide material containing, for example, any one of yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), niobium (Nb), and tantalum (Ta). The first insulating layer 4 may also comprise other elements, such as silicon and nitrogen. The first insulating layer 4 is formed by using a film formation method such as chemical vapor deposition (hereinafter referred to as "CVD") and sputtering.

The first conductive layer 10 may comprise a conductive material, for example comprising a metal or a metal compound. In the present embodiment, the first conductive layer 10 may include, for example, titanium nitride (TiN). The first conductive layer 10 can be formed by using a film formation method such as CVD and sputtering. The first cover insulating layer 15 may include, for example, silicon dioxide (SiO)₂) And (3) a membrane. The first insulating cover layer 15 may be formed by CVD, for example.

After the laminated film is deposited as described above, a photoresist pattern 18 is formed on the semiconductor substrate 1. The photoresist pattern 18 is formed by a known photolithography method. The photoresist pattern 18 is formed by patterning so as to have a shape corresponding to the first portion G described below.

The first insulating cover layer 15 and the first conductive layer 10 are sequentially removed by performing anisotropic dry etching using the photoresist pattern 18 used as an etching mask. Then, for example, by O₂The photoresist pattern 18 is removed by plasma ashing. Therefore, as shown in fig. 5, the first portion G in which the first conductive film 10a and the first cover insulating film 15a are laminated on the first well 1a remains, and the first insulating layer 4 is exposed on the second well 1 b.

As shown in fig. 6, a second conductive layer 11 and a second insulating cover layer 20 are formed on the top surface of the semiconductor substrate 1 on which the first portion G is formed. The second conductive layer 11 may comprise a conductive material, for example comprising a metal or a metal compound. In the present embodiment, the second conductive layer 11 may include, for example, titanium nitride (TiN). The second conductive layer 11 can be formed by using a film formation method such as CVD and sputtering.

The second conductive layer 11 and the first conductive layer 10 have different work functions. The first conductive layer 10 and the second conductive layer 11 include materials having different elemental composition ratios. In this embodiment, the composition ratio of titanium (Ti) and nitrogen (N) is different in the first conductive layer 10 and the second conductive layer 11. The work function of titanium nitride can be controlled by controlling the composition ratio of titanium (Ti) and nitrogen (N). The composition ratio of the first conductive film 10a is set to be optimal for the gate electrode of the N-channel MOSFET disposed in the first well 1 a. The composition ratio of the second conductive film 11a is set to be optimal for the gate electrode of the P-channel MOSFET provided in the second well 1 b.

The second insulating cover layer 20 may include, for example, silicon dioxide (SiO)₂) And (3) a membrane. The second insulating cover layer 20 may be formed by CVD, for example.

At this time, the second conductive layer 11 and the second cover insulating layer 20 are also laminated on the side of the first portion G to form a film. The stacked structure including the second conductive layer 11 and the second insulating cover layer 20 has a thickness T.

After the laminated film is deposited as described above, a photoresist pattern 22 is formed on the semiconductor substrate 1. The photoresist pattern 22 is formed by a known photolithography method. The photoresist pattern 22 is formed by patterning to have a shape corresponding to the second portion H described below. A stacked structure having a thickness T and including the second conductive layer 11 and the second capping insulating layer 20 is located on a side of the first portion G. In some embodiments, the photoresist pattern 22 may be disposed at a distance from the side T or more of the first portion G. In other embodiments, the photoresist pattern 22 may be disposed at a distance less than T from the side of the first portion G.

The second insulating cover layer 20 and the second conductive layer 11 are sequentially removed by performing anisotropic dry etching using the photoresist pattern 22 used as an etching mask. Then, for example, by O₂The photoresist pattern 22 is removed by plasma ashing. Thus, as shown in fig. 7, the first portion G remains on the first well 1a, and the second portion H is formed in which the second conductive film 11a and the second cover insulating filmThe film 20a is laminated on the second well 1 b. The second portion H has a pattern transferred from the photoresist pattern 22. In the portions where the first portion G and the second portion H are not formed, the first insulating layer 4 is exposed. The second portion H is disposed at a distance from the side T or more of the first portion G. The second portion H may be disposed closer to the side of the first portion G by a minimum distance T.

As shown in fig. 7, the exposed first insulating layer 4 is removed by wet etching, in which the first portion G including the first cover insulating film 15a and the second portion H including the second cover insulating film 20a are used as an etching mask. As shown in fig. 8, the first cover insulating film 15a and the second cover insulating film 20a are then removed by etching with, for example, a buffered hydrogen fluoride solution. This results in a structure J in which the first insulating film 4a and the first conductive film 10a are laminated and a structure K in which the first insulating film 4a and the second conductive film 11a are laminated.

As shown in fig. 9, a third conductive layer 12, a fourth conductive layer 13, and a second insulating layer 24 are formed on the semiconductor substrate 1 on which the structure J and the structure K are formed. The third conductive layer 12 may comprise, for example, polysilicon. The third conductive layer 12 may be doped with impurities, such as phosphorus (P) or boron (B). The third conductive layer 12 may be formed by CVD, for example. The fourth conductive layer 13 may include, for example, metal. In the present embodiment, the fourth conductive layer 13 may include, for example, tungsten (W). The fourth conductive layer 13 may be formed by CVD, for example. The second insulating layer 24 may comprise, for example, silicon dioxide (SiO)₂) And (3) a membrane. The second insulating layer 24 may be formed by CVD, for example.

After the laminated film is deposited as described above, a photoresist pattern 26 is formed on the semiconductor substrate 1. The photoresist pattern 26 is formed by a known photolithography method. A photoresist pattern 26 is formed by patterning so as to have a shape corresponding to the first gate electrode 6, the second gate electrode 7, and the third gate electrode 8 connecting the first and second electrodes, which will be described below.

As shown in fig. 2, the second insulating layer 24, the fourth conductive layer 13, and the third conductive layer 12 are patterned by anisotropic dry etching using a photoresist pattern 26 serving as an etching mask. Then, for example, by O₂Plasma with a plasma chamberThe photoresist pattern 26 is removed by bulk ashing. The foregoing process steps result in the first gate electrode 6, the second gate electrode 7, and the third gate electrode 8 as shown in fig. 2, 3A, 3B, and 3C. Finally, the semiconductor device 100 is provided by the aforementioned process steps.

The above embodiment has the following advantageous effects.

The distance between the first portion G and the second portion H is one of factors determining the width E of the isolation region 2, i.e., the PN isolation width E. The reduction in the distance between the first portion G and the second portion H results in a reduction in the PN isolation width E. In turn, the reduction in the PN isolation width E leads to a reduction in the chip area of the semiconductor device 100. In the semiconductor device 100 and the manufacturing method thereof according to the embodiment, the first portion G including the first conductive film 10a and the second portion H including the second conductive film 11a are formed in different process steps, and the third conductive film 12a, the fourth conductive film 13a, and the second insulating film 24a are formed in the same process step. When the second portion H is formed adjacent to the first portion G, the second conductive layer 11 and the second insulating cover layer 20 are formed. Therefore, the second portion H may be disposed closer to the side of the first portion G, and the minimum distance is the thickness T of the stacked structure including the second conductive layer 11 and the second capping insulating layer 20. In the semiconductor device 100 and the method of manufacturing the same according to the embodiment, the PN isolation width E can be reduced to the distance T, which can reduce the chip area of the semiconductor device 100. Therefore, the semiconductor device 100 and the manufacturing method thereof can be provided at low cost.

The work function of the first conductive film 10a included in the first gate electrode 6 provided on the first well 1a is different from the work function of the second conductive film 11a included in the second gate electrode 7 provided on the second well 1 b. The work function of the first conductive film 10a is set to a material suitable for the gate electrode of the N-channel MOSFET. The work function of the second conductive film 11a is set to a material suitable for the gate electrode of the P-channel MOSFET. This can improve the performance of a CMOS circuit including an N-channel MOSFET and a P-channel MOSFET, thereby providing the semiconductor device 100 giving higher performance.

In the first gate electrode 6 provided on the first well 1a and the second gate electrode 7 provided on the second well 1b, the third conductive film 12a, the fourth conductive film 13a, and the second insulating film 24a are formed in the same process step. This can reduce the number of process steps compared to the case where they are formed independently in different process steps. Therefore, the semiconductor device 100 and the manufacturing method thereof can be provided at low cost.

As described above, the DRAM is described as an example of the semiconductor apparatus 100 according to various embodiments, but the above description is only one example and is not intended to be limited to the DRAM. Memory devices other than DRAMs, such as Static Random Access Memory (SRAM), flash memory, Erasable Programmable Read Only Memory (EPROM), Magnetoresistive Random Access Memory (MRAM), and phase change memory, may also be used as the semiconductor device 100. Further, devices other than the memory, including logic ICs such as a microprocessor and an Application Specific Integrated Circuit (ASIC), can also be used as the semiconductor device 100 according to the foregoing embodiment.

Although the present invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In addition, other modifications within the scope of the invention will be apparent to those skilled in the art based upon this disclosure. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. It should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed inventions. Thus, the scope of at least some of the inventions disclosed herein should not be limited by the specific disclosed embodiments described above.