JP2005203562A - Semiconductor device and manufacturing method of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device of a low cost with a protecting film which is excellent in step coverage, and to provide its manufacturing method. <P>SOLUTION: The level difference of a device surface is relaxed by making a protecting film 1 expand toward the end by burying up to the side wall 87a of a copper electrode 87 by properly setting the viscosity of an application insulating film for forming the protecting film 1. A protecting film 2 covers from top of the upper circumferential part 87b of the copper electrode 87 to a top 87c by properly setting the viscosity of the application insulating film for forming the protecting film 2. Consequently, the level difference of the device surface is relaxed by the protecting film 1. Therefore, when the application insulating film which becomes the protecting film 2 is applied, material degradation is hardly generated in the application insulating film covering from top of the upper circumferential edge part 87b of the copper electrode 87 to the top 87c and the protecting film 2 in a portion covering each of the parts 87b, 87c becomes thick, thus improving step coverage of the protecting films 1, 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device, and more particularly to a semiconductor device provided with a protective film for protecting an electrode and a method for manufacturing the semiconductor device.

Conventionally, various semiconductor devices have been proposed in which a coating insulating film such as an SOG (Spin coating On Glass) film is formed as a protective film on an electrode or a wiring layer (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2003-149681 (pages 2 and 3, FIG. 1)

12 and 13 are schematic cross-sectional views for explaining a conventional method of manufacturing a semiconductor device in which a coating insulating film is formed as a protective film on an electrode.

Step 1 (FIG. 12A): PVD (Physical Vapor Depos) on the single crystal silicon substrate 81.
The aluminum alloy film is formed by using the (ition) method, and the wiring layer 82 is formed by patterning the aluminum alloy film. Next, CVD (Chemic) is formed on the entire surface of the substrate 81 including the wiring layer 82.
A protective silicon nitride film 83 is formed using an al Vapor Deposition method, and the silicon nitride film 83 on the wiring layer 82 is removed (etched back) using a dry etching method. continue,
A barrier metal layer 84 and a seed layer 85 are formed in this order on the exposed wiring layer 82 and silicon nitride film 83 by using the PVD method.

Then, a thick photoresist film 86 is formed on the seed layer 85, the photoresist film 86 above the wiring layer 82 is removed by using a photolithography method, and an electrode forming aperture 86a is formed in the photoresist film 86. To do. Here, the film thickness of the photoresist film 86 needs to be formed to be sufficiently thicker than the film thickness (height) of a copper electrode 87 described later.

Thus, when the thickness of the photoresist film 86 is large, the shape of the electrode forming aperture 86a becomes narrower as the cross-sectional area gradually decreases from the top to the bottom due to the exposure characteristics of the photolithography method. It becomes a thing. For example, when the planar shape of the electrode forming aperture 86a is substantially circular, the shape is a tapered shape whose diameter gradually decreases conically from the top to the bottom.

Step 2 (FIG. 12B): Copper (or copper alloy) is deposited on the seed layer 85 exposed at the bottom of the electrode forming aperture 86a using a plating method, and the inside of the electrode forming aperture 86a is formed. A copper electrode 87 is formed by filling. At this time, the seed layer 85 functions as a copper seed deposited by a plating method. As a material for the seed layer 85, for example, copper, gold, ruthenium, platinum or the like may be used. The barrier metal layer 84 is provided to prevent copper in the copper electrode 87 from diffusing into the substrate 81, the silicon nitride film 83, and the like. The material of the barrier metal layer 84 is, for example, an alloy of titanium or tungsten (TiN or Ti
W etc.) may be used.

Step 3 (FIG. 12C): The photoresist film 86 is removed using an ashing method or the like,
The seed layer 85 and the copper electrode 87 are exposed. Here, the shape of the copper electrode 87 is in accordance with the shape of the electrode-forming opening 86a, and the cross-sectional area gradually decreases from the upper part to the lower part and becomes narrower. For example, when the planar shape of the copper electrode 87 is substantially circular, the shape of the copper electrode 87 becomes a tapered shape with a diameter gradually decreasing from a top to a bottom. And
The side wall 87a of the copper electrode 87 has an acute angle gradient with respect to the surface of the substrate 81 and has an undercut shape.

Step 4 (FIG. 13A): barrier metal layer 84 and seed layer 85 below copper electrode 87
The barrier metal layer 84 and the seed layer 85 exposed on the device surface are removed using a wet etching method. At this time, the upper peripheral edge of the copper electrode 87 is also scraped off to form an upper peripheral edge 87b with a radius.

Step 5 (FIGS. 13B and 13C): A coating insulating film is applied to the entire surface of the device including the copper electrode 87 and the silicon nitride film 83, and then cured to form a protective film 88. The protective film 8
For example, SOG, polyimide, methylsiloxane polymer, or the like may be used as a material of the coating insulating film for forming the film 8. In particular, polyimide is optimal as the protective film 88 because it has low moisture permeability, high heat resistance, and high adhesion to the resin material when the substrate 81 is molded with a resin material (such as an epoxy resin).

In recent years, semiconductor devices such as relays that require a large driving current (for example, 15 amperes), DMOS (Double diffused MOS) transistors, LDMOS (Laterally Diffu)
In power devices such as sed MOS transistors, it is required to reduce the resistance of electrode portions (relay termination electrodes, source / drain electrodes of MOS transistors) in order to reduce current loss. For this reason, copper having a smaller electrical resistance than an aluminum alloy that has been conventionally used as an electrode material is used, and the size of the electrode is increased.

And with the enlargement of an electrode, the height of the electrode is also increased (the film thickness of the electrode is increased). For example, while the film thickness of a conventional electrode made of an aluminum alloy was 1 μm or less, the film thickness of a copper electrode through which a large current flows may be about 10 μm, which is 10 times or more that of the conventional one.

In order to set the film thickness (height) of the copper electrode 87 shown in FIGS. 12 and 13 to about 10 μm,
The film thickness of the photoresist film 86 needs to be at least 10 μm. When the thickness of the photoresist film 86 is increased, as described above, due to the exposure characteristics of the photolithography method, the shape of the electrode forming aperture 86a gradually decreases in cross section from the top to the bottom. It will be a waste. As a result, the shape of the copper electrode 87 also conforms to the shape of the electrode forming aperture 86a, and the cross-sectional area gradually decreases from the upper part to the lower part and becomes narrower.

Then, when forming the protective film 88 as shown in FIGS. 13B and 13C, when a coating insulating film serving as the protective film 88 is applied, the upper peripheral edge of the copper electrode 87 is applied by the surface tension of the coating insulating film. The thickness of the coating insulating film covering the portion 87b and the top portion 87c is reduced by thinning,
There is a problem that the step coverage of the protective film 88 is lowered.

Here, when the coating amount of the coating insulating film serving as the protective film 88 is small, as shown in FIG. 13C, the protective film 88 covering the upper peripheral edge 87b of the electrode 87 becomes extremely thin, and cracks 88a and Separation 88b may occur. If a moisture ingress path such as a crack 88a or a separation 88b occurs in the protective film 88, moisture may enter the electrode 87 from the moisture ingress path and cause a short circuit.

In order to prevent the crack 88a and the peeling 88b of the protective film 88, the coating amount of the coating insulating film to be the protective film 88 is increased, and the protection covering the upper peripheral edge 87b of the electrode 87 as shown in FIG. The film 88 may be thickened. However, the material of the coating insulating film for forming the protective film 88 is generally expensive. In particular, the optimum polyimide as the protective film 88 is very expensive.
If 8 is thickened, there is a problem that the manufacturing cost (material cost) increases.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a low-cost semiconductor device including a protective film excellent in step coverage and a method for manufacturing the same.

(Claim 1: corresponds to the first to third embodiments)
Invention of Claim 1 is a semiconductor device provided with the electrode formed on the board | substrate, and the protective film formed with the coating insulating film in order to protect the electrode, Comprising: The said protective film is the said protective film, A first protective film embedded in the side wall of the electrode and spreading in a skirt shape; and a second covering the upper part of the electrode
It is technically characterized by comprising a protective film.

(Claim 2: corresponds to the second embodiment)
According to a second aspect of the present invention, in the semiconductor device according to the first aspect, the second protective film is
A technical feature is to cover only the upper peripheral edge and top of the electrode.

(Claim 3: corresponds to the third embodiment)
According to a third aspect of the present invention, in the semiconductor device according to the first aspect, at least one of the first protective film and the second protective film has a multilayer structure.

(Claim 4: Corresponds to the first to third embodiments)
According to a fourth aspect of the present invention, there is provided a first step of forming an electrode on a substrate, and a second step of forming a first protective film by applying a first coating insulating film on the substrate including the electrode and then curing the coating. And a third step of forming a second protective film by applying a second coating insulating film on the electrode and the first protective film, and then curing the second coated insulating film. It is technically characterized that the side wall portion is buried and spreads in a skirt shape, and the second protective film covers the upper portion of the electrode.

(Claim 5: Corresponds to the fourth embodiment or the fifth embodiment)
The invention according to claim 5 includes an electrode formed on the substrate, a dummy member formed on the substrate in the vicinity of the electrode, and a coating insulating film for covering and protecting the electrode and the dummy member. A technical feature is that the protective film is provided.

(Claim 6: corresponds to the fourth embodiment)
The invention according to claim 6 is the semiconductor device according to claim 5, wherein the dummy member is formed of the same material as the electrode.

(Claim 7: Corresponds to the fourth embodiment)
The invention according to claim 7 is a first step of forming a dummy member on the substrate in the vicinity of the electrode, and simultaneously forming a dummy member with the same material as the electrode on the substrate, and the electrode and the dummy member. And a second step of forming a protective film by applying a coating insulating film on a substrate including the second insulating layer.

(Claim 8: corresponds to the fifth embodiment)
The invention described in claim 8 is a semiconductor device according to claim 5, wherein the dummy member is formed of an insulating material.

(Claim 9: Corresponds to the fifth embodiment)
According to a ninth aspect of the present invention, there is provided a first step of forming a dummy film by applying a first coating insulating film on a substrate and then patterning the dummy film, and forming electrode positions on the substrate by patterning the dummy film A second step of forming a dummy member in the vicinity of the substrate, a third step of forming an electrode at the position where the electrode is formed on the substrate, and a second coating insulating film is applied on the substrate including the electrode and the dummy member And a fourth step of forming a protective film by subsequent curing.

(Claim 1)
In the first aspect of the present invention, the viscosity of the coating insulating film for forming the first protective film is appropriately set so that the first protective film embeds up to the side wall portion of the electrode and spreads in a skirt shape. Reduce the step on the device surface. Then, by appropriately setting the viscosity of the coating insulating film for forming the second protective film, the second protective film covers from the upper peripheral edge to the top of the electrode. Note that the viscosity and the coating amount of the coating insulating film for forming each protective film may be set by experimentally finding the optimum values by cut-and-try.

As a result, since the step on the device surface is relaxed by the first protective film, when the coating insulating film serving as the second protective film is applied, the coating insulating film covering from the upper peripheral edge to the top of the electrode is rejected. Since the thickness of the second protective film in the portion covering the upper peripheral edge and the top is increased, each protective film can be formed even if the electrode height is increased (even if the electrode film thickness is increased). The step coverage can be improved. Therefore, according to the first aspect of the present invention, it is possible to prevent cracking and peeling of the protective film as shown in FIG. 13C of the prior art, and each protective film reliably prevents moisture from entering, and thus short-circuited. Does not happen.

And according to invention of Claim 1, compared with forming a thick protective film as shown to FIG. 13 (B) of a prior art, the total coating amount of the coating insulating film used as each protective film is small. Therefore, it is possible to reduce the material cost of the expensive coating insulating film and to reduce the manufacturing cost.

(Claim 2)
According to the invention described in claim 2, since it is possible to reduce the coating amount of the coating insulating film serving as the second protective film, compared to the invention described in claim 1, the invention described in claim 1 is provided. The manufacturing cost can be further reduced than the invention.

(Claim 3)
According to the third aspect of the present invention, compared with the first aspect of the invention, the step coverage of the entire protective film is equivalent to the multilayer structure of at least one of the first protective film and the second protective film. It is possible to further improve the property, and the electrodes can be reliably covered and protected by each protective film.

(Claim 4)
According to the invention described in claim 4, it is possible to manufacture the semiconductor device described in claim 1, and the same effect as that of the invention described in claim 1 can be obtained.

(Claim 5)
According to the invention of claim 5, when a coating insulating film for forming a protective film is applied,
The coating insulating film fills the gap between the electrode and the dummy member, and the surface tension of the coating insulating film filling the gap causes the coating insulating film covering from the upper peripheral edge to the top of the electrode to be rejected. It becomes difficult to occur. The viscosity and the coating amount of the coating insulating film for forming the protective film may be set by experimentally finding the optimum value by cut-and-try.

As a result, the thickness of the protective film covering the upper peripheral edge and the top of the electrode is increased, and the step on the surface of the protective film is reduced, so that even if the electrode height is increased (the electrode thickness is increased). However, the step coverage of the protective film can be improved. Therefore, according to the invention described in claim 5, it is possible to prevent cracking and peeling of the protective film as shown in FIG. 13C of the prior art, and the protective film reliably prevents moisture from entering, so that a short circuit is prevented. I don't get up.

According to the invention described in claim 5, compared to forming a thick protective film as shown in FIG. 13B of the prior art, the coating insulating film that becomes the protective film only by the volume of the dummy member Therefore, it is possible to reduce the manufacturing cost by reducing the material cost of the expensive coating insulating film.

(Claim 6)
According to the sixth aspect of the present invention, since the dummy member is formed of the same material as the electrode, the dummy member can be formed at the same time in the same process as the electrode. No additional process is required, and there is no increase in manufacturing cost due to the formation of the dummy member.

(Claim 7)
According to the seventh aspect of the invention, the semiconductor device according to the sixth aspect can be manufactured, and the same effect as that of the sixth aspect of the invention can be obtained.

(Claim 8)
According to the eighth aspect of the present invention, since the dummy member is formed of an insulating material that is a different material from the electrode, the height from the substrate surface to the top of the electrode (electrode height) is reduced from the substrate surface. It is possible to reduce the height to the top of the dummy member (dummy member height). Therefore, the coating amount of the coating insulating film serving as the protective film can be reduced by the amount that the dummy member height is reduced with respect to the electrode height. The dummy member height may be set by experimentally finding the optimum value by cutting and trying.

(Claim 9)
According to the invention described in claim 9, since the dummy member is formed by the first coating insulating film which is an insulating material, the semiconductor device according to claim 8 can be manufactured. The same effect as that of the present invention can be obtained.

Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. In each embodiment, the same constituent members as those in the prior art shown in FIGS. 12 and 13 are denoted by the same reference numerals. Moreover, in each embodiment, description is abbreviate | omitted about the location of the same content as 1st Embodiment.

(First embodiment)
1 and 12 are schematic cross-sectional views for explaining the semiconductor device manufacturing method of the first embodiment.

Step 1 to Step 3 (FIGS. 12A to 12C): The same as Step 1 to Step 3 of the prior art.
Step 4 (FIG. 1A): Same as step 4 in the prior art (FIG. 13A).

Step 5 (FIG. 1B): A coating insulating film is applied to the entire surface of the device including the copper electrode 87 and the silicon nitride film 83 and then cured to form the protective film 1.

Step 6 (FIG. 1C): A coating insulating film is applied to the entire surface of the device including the copper electrode 87 and the protective film 1 and then cured to form the protective film 2.

[Operations and effects of the first embodiment]
In the semiconductor device of the first embodiment, protective films 1 and 2 for covering and protecting the surface of the device
The protective film 1 (first protective film) that embeds up to the side wall 87a of the copper electrode 87, and the protective film 2 (second protective film) that covers the protective film 1 and the upper peripheral portion 87b of the copper electrode 87 from the top 87c. And 2
It has a layered structure. In addition, as a material of the coating insulating film for forming each protective film 1, 2,
Various coating insulating films may be used in the same manner as the protective film 88 of the prior art.

Then, in step 5 (FIG. 1B), the protective film 1 embeds up to the side wall 87a of the copper electrode 87 by setting the viscosity of the coating insulating film for forming the protective film 1 as appropriate. The steps on the device surface are alleviated so as to spread. In step 6 (FIG. 1C),
By appropriately setting the viscosity of the coating insulating film for forming the protective film 2, the protective film 2 covers the upper peripheral portion 87 b to the top portion 87 c of the copper electrode 87.

The viscosity and the coating amount of the coating insulating film for forming the protective films 1 and 2 may be set by experimentally finding the optimum values by cut and try. For example, the viscosity of the protective film 1 may be set smaller than the viscosity of the protective film 2. That is, the purpose of the protective film 1 is to fill the undercut portion of the side wall 87 a of the copper electrode 87.

As a result, since the step on the device surface is relaxed by the protective film 1, the coating insulation covering from the upper peripheral edge 87 b to the top 87 c of the copper electrode 87 when the coating insulating film to be the protective film 2 is applied. Protective film 2 in the part covering each part 87b, 87c is less likely to cause meat erosion.
The film thickness becomes thicker. Therefore, even if the copper electrode 87 is thick (for example, about 10 μm), the step coverage of the protective films 1 and 2 can be improved.

Therefore, according to the first embodiment, it is possible to prevent the crack 88a and the separation 88b of the protective film 88 as shown in FIG. 13C of the prior art, and the protective films 1 and 2 reliably prevent moisture from entering. Therefore, a short circuit does not occur.

In addition, according to the first embodiment, a thick protective film 88 as shown in FIG.
The total coating amount of the coating insulating film that becomes each of the protective films 1 and 2 can be reduced compared to forming the protective film 1, thereby reducing the material cost of the expensive coating insulating film and reducing the manufacturing cost. Can be achieved.

(Second Embodiment)
2 and 12 are schematic cross-sectional views for explaining the semiconductor device manufacturing method of the second embodiment.

Step 1 to Step 3 (FIGS. 12A to 12C): The same as Step 1 to Step 3 of the prior art.
Step 4 (FIG. 2A): Same as step 4 in the prior art (FIG. 13A). Step 5 (FIG. 2
(B)): Same as step 5 in the first embodiment (FIG. 1B).

Step 6 (FIG. 2C): A coating insulating film is applied only from the upper peripheral edge 87b of the copper electrode 87 to the top 87c, and then cured to form the protective film 3.

[Operation and Effect of Second Embodiment]
In the semiconductor device of the second embodiment, protective films 1 and 3 for covering and protecting the surface of the device
2 of the protective film 1 (first protective film) that embeds up to the side wall 87a of the copper electrode 87 and the protective film 3 (second protective film) that covers only the top portion 87c from the upper peripheral edge portion 87b of the copper electrode 87. It has a layered structure. In addition, as a material of the coating insulating film for forming the protective films 1 and 3, various coating insulating films may be used similarly to the protective film 88 of the prior art.

In step 6 (FIG. 2C), the protective film 3 is formed on the upper peripheral edge 87b of the copper electrode 87 by setting the viscosity of the coating insulating film for forming the protective film 3 to an appropriate high viscosity. Only the top 87c is covered.

Note that the viscosity and the coating amount of the coating insulating film for forming the protective films 1 and 3 may be set by experimentally finding the optimum values by cut-and-try. For example, the viscosity of the protective film 1 may be set smaller than the viscosity of the protective film 3. That is, the purpose of the protective film 1 is to fill the undercut portion of the side wall 87 a of the copper electrode 87.

As a result, when a coating insulating film serving as the protective film 3 is applied, the thick coating insulating film covers only the top peripheral portion 87c from the upper peripheral portion 87b of the copper electrode 87 due to the surface tension of the coating insulating film, and the respective portions 87b, 87c. The film thickness of the protective film 3 covering the film increases. Therefore, even if the copper electrode 87 is thick (for example, about 10 μm), the step coverage of the protective films 1 and 3 can be improved.

Therefore, according to the second embodiment, similarly to the first embodiment, it is possible to prevent the crack 88a and the separation 88b of the protective film 88 as shown in FIG. Does not cause a short circuit to prevent moisture from entering.

In addition, according to the second embodiment, it is possible to reduce the coating amount of the coating insulating film to be the protective film 3 as compared with the protective film 2 of the first embodiment. Furthermore, the manufacturing cost can be reduced.

(Third embodiment)
3 and 12 are schematic cross-sectional views for explaining the semiconductor device manufacturing method of the third embodiment.

Step 1 to Step 3 (FIGS. 12A to 12C): The same as Step 1 to Step 3 of the prior art.
Step 4 (FIG. 2A): Same as step 4 in the prior art (FIG. 13A).

Step 5 (FIG. 3B): A coating insulating film is applied to the entire surface of the device including the copper electrode 87 and the silicon nitride film 83 and then cured to form the protective film 4. Next, a coating insulating film is applied to the entire surface of the device including the copper electrode 87 and the protective film 4 and then cured to form the protective film 5.

Step 6 (FIG. 3C): A coating insulating film is applied to the entire surface of the device including the copper electrode 87 and the protective film 4 and then cured to form the protective film 6. Next, a coating insulating film is applied on the protective film 4 and then cured to form the protective film 7.

[Operation and Effect of Third Embodiment]
In the semiconductor device of the third embodiment, protective films 4 to 7 are provided to cover and protect the surface of the device.
However, the two-layer protective films 4 and 5 (first protective film) that embed up to the side wall 87a of the copper electrode 87 and the two-layer protective films 6 and 7 (from the upper peripheral edge 87b to the top 87c of the copper electrode 87) 4 layers in total with the second protective film). In addition, as a material of the coating insulating film for forming each protective film 4-7, various coating insulating films may be used similarly to the protective film 88 of the prior art.

In step 5 (FIG. 3B), the viscosity of the coating insulating film for forming the protective films 4 and 5 is appropriately set so that the protective films 4 and 5 reach the side wall 87a of the copper electrode 87. The step on the surface of the device is eased by embedding and spreading in a skirt shape. Here, as compared with the case where the side wall 87a of the copper electrode 87 is buried with only one protective film 1 as in the first embodiment, the third
In the embodiment, the side walls 87a of the copper electrode 87 are formed by sequentially forming the two protective films 4 and 5.
Can be reliably embedded by the protective films 4 and 5.

Further, in step 6 (FIG. 3C), the protective film 6, 7 is formed on the upper peripheral portion of the copper electrode 87 by appropriately setting the viscosity of the coating insulating film for forming the protective film 6, 7. Cover from 87b to the top 87c.

Note that the viscosity and the coating amount of the coating insulating film for forming each of the protective films 4 to 7 may be set by experimentally finding the optimum values by cut-and-try. For example, the viscosity of the protective films 4 and 5 may be set smaller than the viscosity of the protective films 6 and 7. That is, the purpose of the protective films 4 and 5 is to fill the undercut shape portion of the side wall 87 a of the copper electrode 87.

As a result, the steps on the device surface are alleviated by the protective films 4 and 5, so that when the coating insulating film to be the protective film 6 is applied, the copper electrode 87 is covered from the upper peripheral edge 87 b to the top 87 c. It is difficult for the coating insulating film to lose its thickness, and the thickness of the protective film 6 covering the portions 87b and 87c increases. Further, since the step on the device surface is further relaxed by the protective film 6 added to the protective films 4 and 5, when the coating insulating film to be the protective film 7 is applied, each portion 87b
, 87c, the thickness of the protective film 7 is increased.

Therefore, compared to covering the copper electrode 87 with only the two protective films 1 and 2 as in the first embodiment, the third embodiment further increases the step coverage of each of the protective films 4 to 7. Thus, the copper electrode 87 can be reliably covered and protected by the two protective films 4 to 7.
In the third embodiment, the four protective films 4 to 7 are formed. However, three or more protective films may be formed.

(Fourth embodiment)
4 and 5 are schematic cross-sectional views for explaining the method for manufacturing the semiconductor device of the fourth embodiment.

Step 1 (FIG. 4A): Similar to Step 1 of the prior art (FIG. 12A), on the substrate 81,
A wiring layer 82, a silicon nitride film 83, a barrier metal layer 84, and a seed layer 85 are sequentially formed.

Then, a thick photoresist film 86 is formed on the seed layer 85, and the photoresist film 86 above the wiring layer 82 is removed by using a photolithography method to form an electrode forming hole 86a, and the wiring layer The photoresist film 86 in the vicinity of both sides of 82 is removed to form dummy member forming openings 86b and 86c. Here, the film thickness of the photoresist film 86 needs to be formed to be sufficiently thicker than the film thickness (height) of a copper electrode 87 described later.

Thus, when the thickness of the photoresist film 86 is large, the shape of each of the apertures 86a to 86c becomes narrower as the cross-sectional area gradually decreases from the top to the bottom due to the exposure characteristics of the photolithography method. It becomes a thing.

Step 2 (FIG. 4B): Copper is deposited on the seed layer 85 exposed at the bottoms of the openings 86a to 86c by using a plating method to fill the openings 86a to 86c with copper electrodes. 87 and the dummy members 11a and 11b are formed simultaneously.

Step 3 (FIG. 4C): The photoresist film 86 is removed using an ashing method or the like to expose the barrier metal layer 84, the seed layer 85, the copper electrode 87, and the dummy members 11a and 11b. Here, the shapes of the copper electrode 87 and the dummy members 11a and 11b are in accordance with the shapes of the openings 86a to 86c, respectively, and the cross-sectional area gradually decreases from the upper part toward the lower part and becomes narrower. become. The side wall 87a of the copper electrode 87 has an acute angle gradient with respect to the surface of the substrate 81 and has an undercut shape.

Step 4 (FIG. 5A): The barrier metal layer 84 and the seed layer 85 exposed on the device surface are removed using a wet etching method except for the barrier metal layer 84 and the seed layer 85 below the copper electrode 87. To do. At this time, the upper peripheral edge of the copper electrode 87 is also scraped off to form an upper peripheral edge 87b with a radius. Moreover, the upper periphery of each dummy member 11a, 11b is also scraped off and rounded.

Step 5 (FIG. 5B): A coating insulating film is applied to the entire surface of the device including the copper electrode 87, the dummy members 11a and 11b, and the silicon nitride film 83, and then cured to form the protective film 12. . In addition, as a material of the coating insulating film for forming the protective film 12, various coating insulating films may be used like the protective film 88 of the prior art.

[Operations and effects of the fourth embodiment]
In the semiconductor device of the fourth embodiment, near both sides of the copper electrode 87 formed on the wiring layer 82,
Dummy members 11a and 11b made of the same material (copper or copper alloy) as the copper electrode 87 are formed, and a protective film 12 covering the copper electrode 87 and the dummy members 11a and 11b is formed.

Therefore, when a coating insulating film to be the protective film 12 is applied, the coating insulating film is a copper electrode 87.
Is applied to cover from the upper peripheral edge 87b to the top 87c of the copper electrode 87 by the surface tension of the coating insulating film that fills the gap S between each of the dummy members 11a and 11b. The insulation film is less likely to be rejected. It should be noted that the viscosity and the coating amount of the coating insulating film for forming the protective film 12 may be set by experimentally finding optimum values by cut-and-try.

As a result, the thickness of the protective film 12 covering the portions 87b and 87c of the copper electrode 87 is increased and the step 12a on the surface of the protective film 12 is reduced, so that even if the thickness of the copper electrode 87 is increased (for example, 10 μm), the step coverage of the protective film 12 can be improved. Therefore, according to the fourth embodiment, it is possible to prevent the crack 88a and the separation 88b of the protective film 88 as shown in FIG. 13C of the prior art, and the protective film 12 reliably prevents the ingress of moisture. Does not happen.

And according to 4th Embodiment, the thick protective film 88 as shown to FIG. 13 (B) of a prior art.
Compared with the formation of the film, the amount of the coating insulating film to be the protective film 12 can be reduced by the volume of each dummy member 11a, 11b, thereby reducing the material cost of the expensive coating insulating film. Thus, the manufacturing cost can be reduced.

In addition, according to the fourth embodiment, since the dummy members 11a and 11b can be formed simultaneously with the copper electrode 87 in the same process, it is not necessary to add a special process for forming the dummy members 11a and 11b. Thus, there is no increase in manufacturing cost due to the formation of the dummy members 11a and 11b.

FIGS. 6A to 6C are plan views for illustrating examples of the planar arrangement of the copper electrode 87 and the dummy members 11a to 11d. 5 is a cross-sectional view taken along the line XX shown in FIGS. 6 (A) and 6 (B).

FIG. 6A shows each of the dummy members 1 in the form of straight strips in the four directions near the periphery of the substantially rectangular copper electrode 87.
This is an example in which 1a to 11d are arranged.

FIG. 6B shows each dummy member 1 in the form of a straight strip in two directions near the periphery of the substantially rectangular copper electrode 87.
This is an example in which 1b and 11d are arranged (that is, an example in which the dummy members 11a and 11c are omitted from FIG. 6A). Note that the dummy members 11c and 11d may be omitted from FIG. Moreover, you may make it leave only any one dummy member selected from each dummy member 11a-11d of FIG. 6 (A).

FIG. 6C shows an example in which substantially annular belt-like dummy members 11 a and 11 b surrounding the vicinity of the substantially rectangular copper electrode 87 are arranged. The width of each dummy member 11a to 11d and the distance from the copper electrode 87 may be set by finding an optimum value experimentally by cut-and-try.

FIG. 7 is a schematic cross-sectional view showing an example of a semiconductor device (semiconductor chip) to which the fourth embodiment is applied. An LDMOS transistor 21, a CMOS 22, a bipolar transistor 23, and a pad portion 24 are formed on the substrate 81, and each element 21 to 24 is an element isolation insulating film 25.
The element is separated by the wiring layer 8 on each element 21 to 24 via the interlayer insulating films 26 and 27.
2 is formed.

The copper electrode 87 is provided as a source / drain electrode of the LDMOS transistor 21 and the CMOS 22 and an electrode of the pad portion 24. Also, each dummy member 11a, 1
1b is provided at a portion (in this example, above the CMOS 22) where the coating insulating film serving as the protective film 12 is likely to lose its thickness because the distance between the copper electrodes 87 is large.

(Fifth embodiment)
8 to 10 are schematic cross-sectional views for explaining the semiconductor device manufacturing method of the fifth embodiment.

Step 1 (FIG. 8A): An aluminum alloy film is formed on the substrate 81 using the PVD method,
The wiring layer 82 is formed by patterning the aluminum alloy film. Next, a protective silicon nitride film 83 is formed on the entire surface of the substrate 81 including the wiring layer 82 by CVD. Subsequently, a thick coating insulating film is applied on the silicon nitride film 83 and then cured to form the dummy film 31. As a material for the coating insulating film for forming the dummy film 31, various coating insulating films may be used as in the case of the protective film 88 of the prior art.

Step 2 (FIG. 8B): Using the photolithography method and the dry etching method, each of the dummy films 31 in the vicinity of both sides of the wiring layer 82 (in the vicinity of both sides of the portion where the electrode 87 is formed) is left in a desired shape. Dummy members 31a and 31b are formed (the dummy film 31 is patterned to form the dummy members 31a and 31b), and the other portions of the dummy film 31 are removed.

Step 3 (FIG. 8C): The silicon nitride film 83 on the wiring layer 82 is removed using a dry etching method. Next, a barrier metal layer 84 and a seed layer 85 are formed in this order on the exposed wiring layer 82, the silicon nitride film 83, and the dummy members 31 a and 31 b using the PVD method.

Step 4 (FIG. 9A): A thick photoresist film 86 is formed on the seed layer 85 including the dummy members 31a and 31b, and the photoresist film 86 above the wiring layer 82 is removed by photolithography. Then, an electrode forming hole 86 a is formed in the photoresist film 86.

Step 5 (FIG. 9B): Copper is deposited on the seed layer 85 exposed at the bottom of the electrode forming aperture 86a by plating to fill the inside of the electrode forming aperture 86a with a copper electrode. 87 is formed.

Step 6 (FIG. 9C): The photoresist film 86 is removed using an ashing method or the like to expose the barrier metal layer 84, the seed layer 85, and the copper electrode 87. Here, the side wall 87a of the copper electrode 87 has an acute angle gradient with respect to the surface of the substrate 81 and has an undercut shape.

Step 7 (FIG. 10A): barrier metal layer 84 and seed layer 85 under copper electrode 87
The barrier metal layer 84 and the seed layer 85 exposed on the device surface are removed using a wet etching method. At this time, the upper peripheral edge of the copper electrode 87 is also scraped off to form an upper peripheral edge 87b with a radius.

Step 8 (FIG. 10B): A coating insulating film is applied to the entire surface of the device including the copper electrode 87 and the silicon nitride film 83 and then cured to form the protective film 12.

[Operation and Effect of Fifth Embodiment]
In the semiconductor device of the fifth embodiment, the dummy members 31a and 31b made of the dummy film 31 are formed near both sides of the copper electrode 87 formed on the wiring layer 82. The copper electrode 87 and the dummy members 31a are formed. , 31b is formed.

Therefore, when a coating insulating film to be the protective film 12 is applied, the coating insulating film is a copper electrode 87.
And the coating covering the space from the upper peripheral edge 87b to the top 87c of the copper electrode 87 by the surface tension of the coating insulating film filling the space S between the dummy members 31a and 31b. The insulation film is less likely to be rejected. It should be noted that the viscosity and the coating amount of the coating insulating film for forming the protective film 12 may be set by experimentally finding optimum values by cut-and-try.

As a result, according to the fifth embodiment, each part 87b of the copper electrode 87, as in the fourth embodiment.
Since the thickness of the protective film 12 covering the portion 87c is increased and the step 12a on the surface of the protective film 12 is reduced, the step coverage of the protective film 12 can be improved.

Then, according to the fifth embodiment, a thick protective film 88 as shown in FIG.
Compared to forming the film, the amount of the coating insulating film to be the protective film 12 can be reduced by the volume of each of the dummy members 31a and 31b, thereby reducing the material cost of the expensive coating insulating film. Thus, the manufacturing cost can be reduced.

In addition, according to the fifth embodiment, each dummy from the surface of the silicon nitride film 83 to the height h1 from the surface of the silicon nitride film 83 to the top 87c of the copper electrode 87, as shown in FIG. It is possible to reduce the height h2 to the top of the members 31a and 31b. Therefore, the coating amount of the coating insulating film that becomes the protective film 12 can be reduced by the amount that the height h2 is reduced with respect to the height h1. The height h2 may be set by experimentally finding the optimum value by cut-and-try.

By the way, in 5th Embodiment, the dummy film | membrane 31 once formed in the device whole surface at the process 1 (FIG. 8 (A)) is the part of each dummy member 31a, 31b in the process 2 (FIG. 8 (B)). Just leave and remove. Therefore, in order to suppress the manufacturing cost, it is necessary to use an inexpensive material (for example, SOG) as the material of the coating insulating film for forming the dummy film 31.

Incidentally, as shown in FIGS. 6 (A) to 6 (C), in the fifth embodiment, dummy members 31a to 31d may be arranged similarly to the dummy members 11a to 11d of the fourth embodiment. FIG. 10 is a cross-sectional view taken along the line XX shown in FIGS.

FIG. 11 is a schematic cross-sectional view showing an example of a semiconductor device (semiconductor chip) to which the fifth embodiment is applied, similarly to the fourth embodiment. Each of the dummy members 31a and 31b is provided in a portion (in this example, above the CMOS 22) where the coating insulating film serving as the protective film 12 is likely to lose its thickness because the distance between the copper electrodes 87 is large.

[Another embodiment]
By the way, the present invention is not limited to the above-described embodiments, and may be embodied as follows. Even in this case, operations and effects equivalent to or more than those of the above-described embodiments can be obtained.

(1) In the arrangement example of the dummy members 11a to 11d and 31a to 31d shown in FIGS. 6 (A) and 6 (C), each dummy member has a straight belt shape, but the shape of each dummy member is an application filling the gap portion S. Any shape may be used as long as it is difficult for the coating insulating film covering the upper peripheral portion 87b of the copper electrode 87 to the top portion 87c to be easily lost due to the surface tension of the insulating film. Also,
In the example shown in FIG. 6 (C), the dummy member has a substantially annular shape. However, as long as the same effect as described above can be obtained, the dummy member may be shaped so that it is partially interrupted at an appropriate location. .

(2) In each of the above embodiments, copper or a copper alloy is used as a material for forming the electrode 87.
Any forming material may be used as long as the height of the electrode 87 can be increased and the resistance can be reduced.

(3) Each of the above embodiments is applied to a device formed on the single crystal silicon substrate 1, but other semiconductor substrates (eg, gallium arsenide substrate, indium gallium arsenide substrate, etc.) or SOI (Silicon On Insulator) It may be applied to a device created on a substrate.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic sectional drawing for demonstrating the manufacturing method of the semiconductor device of 1st Embodiment which actualized this invention. The schematic sectional drawing for demonstrating the manufacturing method of the semiconductor device of 2nd Embodiment which actualized this invention. The schematic sectional drawing for demonstrating the manufacturing method of the semiconductor device of 3rd Embodiment which actualized this invention. FIG. 9 is a schematic cross-sectional view for explaining a method for manufacturing a semiconductor device according to a fourth embodiment embodying the present invention. FIG. 9 is a schematic cross-sectional view for explaining a method for manufacturing a semiconductor device according to a fourth embodiment embodying the present invention. The top view for showing each example of plane arrangement of copper electrode 87 and dummy members 11a-11d and 31a-31d. FIG. 10 is a schematic cross-sectional view showing an example of a semiconductor device (semiconductor chip) to which the fourth embodiment is applied. FIG. 9 is a schematic cross-sectional view for explaining a method for manufacturing a semiconductor device according to a fifth embodiment embodying the present invention. FIG. 9 is a schematic cross-sectional view for explaining a method for manufacturing a semiconductor device according to a fifth embodiment embodying the present invention. FIG. 9 is a schematic cross-sectional view for explaining a method for manufacturing a semiconductor device according to a fifth embodiment embodying the present invention. FIG. 10 is a schematic cross-sectional view showing an example of a semiconductor device (semiconductor chip) to which the fifth embodiment is applied. FIG. 10 is a schematic cross-sectional view for explaining a conventional method for manufacturing a semiconductor device. FIG. 10 is a schematic cross-sectional view for explaining a conventional method for manufacturing a semiconductor device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1-7,12 ... Protective film 11a-11d, 31a-31d ... Dummy member 31 ... Dummy film | membrane 81 ... Silicon substrate 87 ... Copper electrode

Claims (9)

A semiconductor device comprising an electrode formed on a substrate and a protective film formed by a coating insulating film to protect the electrode,
The protective film is
A first protective film embedded in the side wall portion of the electrode and spreading in a skirt shape;
A semiconductor device comprising a second protective film covering an upper portion of the electrode. The semiconductor device according to claim 1,
The second protective film covers only the upper peripheral edge and the top of the electrode. The semiconductor device according to claim 1,
At least one of the first protective film and the second protective film has a multilayer structure. A first step of forming an electrode on a substrate;
A second step of forming a first protective film by applying a first coating insulating film on the substrate including the electrode and then curing the coating;
A second coating insulating film is applied on the electrode and the first protective film, and then cured to be second.
A third step of forming a protective film,
The first protective film fills up the side wall portion of the electrode and spreads in a skirt shape,
The method for manufacturing a semiconductor device, wherein the second protective film covers an upper portion of the electrode. An electrode formed on a substrate;
A dummy member formed on the substrate in the vicinity of the electrode;
A semiconductor device comprising: a protective film formed of a coating insulating film to cover and protect the electrode and the dummy member. The semiconductor device according to claim 5,
The semiconductor device, wherein the dummy member is made of the same material as the electrode. A first step of forming an electrode on the substrate and simultaneously forming a dummy member on the substrate in the vicinity of the electrode with the same material as the electrode;
And a second step of forming a protective film by applying a coating insulating film on the substrate including the electrode and the dummy member, and forming a protective film. The semiconductor device according to claim 5,
The semiconductor device, wherein the dummy member is made of an insulating material. A first step of forming a dummy film by applying a first coating insulating film on the substrate and then curing the first coating insulating film;
A second step of patterning the dummy film to form a dummy member in the vicinity of an electrode formation location on the substrate;
A third step of forming an electrode at the electrode formation location on the substrate;
And a fourth step of forming a protective film by applying a second coating insulating film on the substrate including the electrode and the dummy member, and then forming the protective film.

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