JP5822000B2 - Semiconductor device - Google Patents

Description

  The present invention relates to a semiconductor device and a manufacturing method thereof, and more particularly to a semiconductor device having a thick wiring and a manufacturing method thereof.

  In semiconductor integrated circuit devices, MOS transistors, which are constituent elements, are being reduced in size and highly integrated for each generation. With the miniaturization of transistors, the width of wiring connected to the transistors tends to be reduced. The operation speed of the integrated circuit is limited by the resistance and parasitic capacitance of the wiring. In order to keep the resistance of narrow wires low, copper or copper alloys have been used instead of aluminum.

  It is difficult to increase the patterning accuracy of copper wiring. Therefore, a damascene method is used in which a wiring trench is formed in the interlayer insulating film and a copper wiring is embedded in the trench. Further, when copper diffuses into the insulating film, it has the property of reducing the insulating properties. In order to prevent copper diffusion, a barrier metal layer is formed on the trench surface, copper wiring is buried in the recess, and unnecessary metal layers on the interlayer insulating film are removed by chemical mechanical polishing (CMP), etc. An insulating cap layer made of SiN, SiCN, SiC or the like having a copper diffusion preventing function is formed on the interlayer insulating film.

  Along with the high integration, problems such as voids also occur in damascene copper wiring, and countermeasures are being studied.

  Japanese Patent Laid-Open No. 2001-15508 discloses that when the trench is filled with a conductive material, if the aspect ratio of the trench increases, the trench cannot be completely filled with the conductive material, and the conductive layer is not filled with the conductive material. It is pointed out that a so-called void is formed, and it is proposed to gradually increase the distance between the side walls defining the trench as the distance from the semiconductor substrate increases.

  In JP 2006-203019 A, as the wiring pattern becomes finer, the barrier metal film becomes thicker at the upper portion of the via side surface and the upper portion of the trench side surface, and the barrier metal film becomes thinner at the lower portion of the via side surface and the lower portion of the trench side surface. Therefore, it is difficult to bury Cu film by electrolytic plating, and it is pointed out that defective filling such as voids occurs inside the via, and it is proposed to round the corner at the bottom of the trench.

  Japanese Patent Laid-Open No. 2006-287086 points out that wiring and via plugs are damaged by electric field concentration and physical stress, and a barrier metal film that covers the bottom and side surfaces of the via hole is a portion that covers the side surface of the via hole at the lower end portion of the via hole. It is proposed that the film thickness of the film be thicker than the film thickness of the portion covering the bottom surface of the via hole.

  Along with higher integration, the number of wiring layers has been increased, and multilayer wiring exceeding 10 layers is also used. In the wiring structure, a lower layer wiring closer to the transistor has a narrower width and a thinner thickness, and an upper layer tends to have a wider and thicker wiring. As the degree of integration increases, it becomes necessary to supply more power to the chip. Lower resistance power supply wiring is required, and the thickness of the upper layer wiring tends to increase.

Further, in a miniaturized portable device or the like, there is a configuration in which a DC-DC converter is provided, and when the output of the power amplifier is low, the voltage is lowered to reduce power consumption. In such applications, for example, an inductor capable of flowing a current of the order of 100 mA is required. In other applications, an inductor capable of passing a large current may be required.
JP 2001-15508 A JP 2006-2-3019 A JP 2006-287086 A

  In order to obtain a wiring capable of flowing a large current, it may be desired to form a wiring having a thickness of several microns. When such a thick wiring that has not been used conventionally is formed, a new problem arises.

According to one aspect of the present invention, a semiconductor substrate, a first insulating cap layer formed over the semiconductor substrate, a via hole and a trench over the via hole formed over the first insulating cap layer are provided. The trench includes an interlayer insulating film having a step-shaped side wall above the via hole, a via conductor formed in the via hole, and a wiring formed in the trench, the via conductor Includes a wiring having a different cross-sectional shape, and a second insulating cap layer formed above the interlayer insulating film, wherein the wiring above the via is provided above the via and has a first thickness exceeding 660 nm . A main portion having a thickness of 1 and a projecting portion provided over the main portion, having a second thickness smaller than the first thickness, and projecting 150 nm or more outward from a side portion of the main portion And including the layer A semiconductor device is provided in which the material of the inter-layer insulating film is different from the material of the first insulating cap layer and the material of the second insulating cap layer.

1A and 1B are cross-sectional views of a wiring structure created in a preliminary experiment and a partially enlarged view thereof, and FIG. 1C is a graph showing the calculated stress intensity factor with respect to the thickness of the copper wiring. 2A and 2B are schematic cross-sectional views for analyzing a process of forming an upper insulating layer after forming a damascene copper wiring. FIG. 3A is a cross-sectional view schematically showing the considered wiring structure, and FIG. 3B is a cross-sectional view of the wiring structure created based on this idea. 4A, 4B, and 4C are graphs showing the calculated stress intensity factors with respect to the wiring thickness t, the overhang width L, and the overhang height h. When, When, 5A is a schematic cross-sectional view of the semiconductor device according to the first embodiment, and FIGS. 5B-5H are schematic cross-sectional views showing a manufacturing process of the wiring structure of FIG. 5A. When, 6A is a schematic cross-sectional view of the semiconductor device according to the second embodiment, and FIGS. 6B-6F are schematic cross-sectional views showing a manufacturing process of the wiring structure of FIG. 6A. When 7A is a schematic cross-sectional view of a semiconductor device according to Example 3, and FIGS. 7B-7F are schematic cross-sectional views showing a manufacturing process of the wiring structure of FIG. 7A. FIG. 8A is a schematic plan view of a wiring structure according to Example 4, and FIGS. 8B and 8C are schematic cross-sectional views showing cross-sectional structures at two locations. 9A to 9E are schematic plan views illustrating a wiring structure according to a modification of the fourth embodiment. 10A and 10B are schematic plan views showing a wiring structure according to a further modification of the fourth embodiment. 11A and 11B are schematic cross-sectional views showing modifications of the inductor. When, 12A is a schematic cross-sectional view of the semiconductor device according to Example 5, FIGS. 12B-12G are schematic cross-sectional views showing the manufacturing process of the wiring structure of FIG. 12A, and FIG. 12H is a schematic cross-sectional view showing the wiring structure of the comparative example. FIG. 10 is a schematic cross-sectional view showing a structure of a modified example of Example 5. It is a schematic sectional drawing which shows the structure of the semiconductor device which has a multilayer wiring.

LS substructure,
ID interlayer insulation film,
W wiring,
BM barrier metal,
TR trench,
CAP cap layer,
MW main wiring area,
t The thickness of the main wiring area,
EXW overhang wiring area,
L width of overhang wiring area,
h Height of overhang wiring area,
LD base insulating film,
11 Silicon oxide film,
12 Hard mask film,
14 barrier metal film,
15 copper layer,
16 Cap membrane,
17 Insulating film,
18 Passivation film,
RM resist mask,
21 and 22 (different etching characteristics) insulating films,
58 Al wiring,
57, 59 TiN film.

  As a preliminary experiment, the inventor made a prototype of a 3.3 μm thick wiring that was not conventionally used together with a 0.6 μm thick wiring that is a conventional thick wiring.

  As shown in FIG. 1A, a first interlayer insulating film ID1 made of silicon oxide having a thickness of about 0.8 μm is formed on a lower structure LS including a silicon substrate, and a first trench TR1 having a depth of about 0.6 μm is formed. Was etched. As the barrier metal film BM1, a Ta film having a thickness of about 20 nm on the flat portion is deposited by sputtering, and as a plating seed layer, a Cu film having a thickness of about 50 nm on the flat portion is deposited by sputtering, and the trench TR1 is embedded. Thus, the first Cu wiring layer W1 was formed by plating, and the unnecessary metal layer on the first interlayer insulating film ID1 was removed by chemical mechanical polishing (CMP). The thickness of the first Cu wiring layer W1 whose surface is flattened is 0.6 μm. A SiC film having a thickness of about 140 nm was deposited as a first insulating cap film CAP1 having a copper diffusion preventing function on the interlayer insulating film ID1 so as to cover the first Cu wiring layer W1.

  A silicon oxide film having a thickness of about 3.8 μm is deposited as a second interlayer insulating film ID2 on the first insulating cap film CAP1, and a second trench TR2 having a dual damascene shape (with a via hole) is formed. Etched. The depth of the via hole is about 0.6 μm, and the depth of the wiring trench is about 3.3 μm. A Ta film having a thickness of about 20 nm on the flat portion as the barrier metal film BM2 and a Cu film having a thickness of about 50 nm on the flat portion as the plating seed layer are deposited by sputtering to fill the trench TR2. The Cu wiring layer W2 was formed by plating, and the unnecessary metal layer on the second interlayer insulating film ID2 was removed by CMP. The thickness of the wiring portion of the second Cu wiring layer W2 whose surface is flattened is 3.3 μm. An SiC film having a thickness of about 70 nm is deposited as a second insulating cap film CAP2 having a copper diffusion preventing function on the second interlayer insulating film ID2 so as to cover the second Cu wiring layer W2. A silicon oxide film ID3 was deposited.

  FIG. 1B is an enlarged view of the peripheral portion of the second Cu wiring layer W2. Peeling PF occurred at the interface between the second Cu wiring layer W2 and the second cap layer CAP2 thereon in the vicinity of the edge portion of the thick second Cu wiring layer W2. No peeling occurred at the interface between the lower first Cu wiring layer W1 and the first cap layer CAP1 thereabove. No peeling occurred at the interface between the 0.6 μm thick copper wiring and the cap layer, and peeling occurred at the interface between the 3.3 μm thick copper wiring and the cap layer. Then, it is presumed that peeling easily occurs. Peeling reduces the reliability of the semiconductor device and shortens the lifetime, and therefore a technique for forming a thick wiring without causing peeling is desired.

  The present inventor conducted stress analysis in order to investigate the cause of peeling. In the stress analysis, as shown in FIG. 1B, assuming that a minute peeling (crack) occurs at the interface between the copper wiring and the cap layer in the vicinity of the edge of the Cu wiring, it is easy for the crack to progress. Is evaluated using an index called a stress intensity factor. A large index indicates that peeling tends to be large. This is a technique often used in fracture mechanics. The thickness t of the copper wiring is changed from a conventionally used thick wiring thickness of 0.6 μm (600 nm) (model M1) to 1500 nm (model M2), 2400 nm (model M3), 3300 nm (model M4) at 900 nm intervals. The stress intensity factor was calculated.

FIG. 1C is a graph showing how the stress intensity factor changes with respect to the thickness of the copper wiring layer. The horizontal axis indicates the thickness t of the copper wiring layer in units (nm), and the vertical axis indicates the stress intensity factor κi in units (Pa · μm ⁻² ). It can be seen that the stress intensity factor κi increases as the thickness t of the copper wiring increases. As a whole, a convex shape is drawn upward. The increase in the stress intensity factor κi is the largest when the thickness t increases from 600 nm to 1500 nm. When a copper wiring having a thickness of more than 600 nm is formed, the applied stress is expected to increase rapidly. The increase in the stress intensity factor κi with respect to the increase in the wiring film thickness every 900 nm gradually decreases with increasing thickness. When the copper wiring with a thickness of 600 nm does not peel off and the result of the peeling with the copper wiring with a thickness of 3300 nm coincides with the experimental result, the stress intensity factor κi = 1.16E8 Pa · μm ⁻ corresponding to the copper wiring with a thickness of 600 nm ^No peeling occurs at ² , but peeling occurs at a stress intensity factor κi = 2.12E8 Pa · μm ⁻² corresponding to a copper wiring having a thickness of 3300 nm.

Consider the cause of peeling. In this model, Cu has a larger thermal expansion coefficient than the surrounding insulators SiO ₂ and SiC. After forming the copper wiring layer, a cap layer and an interlayer insulating film are deposited at a temperature of about 400 ° C., for example, and then the temperature is lowered to room temperature. In the temperature lowering process, the copper wiring contracts more than the cap layer and the interlayer insulating film.

  FIG. 2A schematically shows a state in which the second cap layer CAP2 and the third interlayer insulating film ID3 are formed on the second interlayer insulating film ID2 in which the copper wiring W2 having a thickness of 3300 nm is embedded. The temperature is about 400 ° C. Thermal expansion during temperature rise is ignored for the time being.

  As shown in FIG. 2B, the temperature is then lowered to room temperature. As the temperature falls, both the copper wiring and the insulating film shrink. The amount of shrinkage of the copper wiring is about an order of magnitude larger than the amount of shrinkage of the insulating film. In the case of a copper wiring having a thickness of 3300 nm, the difference in heat shrinkage is on the order of 10 nm in the height direction. If the second copper wiring surrounded by the second interlayer insulating film becomes relatively low on the order of 10 nm, it is considered that the second cap layer CAP2 is exposed to a relative height change of the order of 10 nm. . Therefore, a large stress is applied to the cap layer CAP2 in the vicinity of the edge of the copper wiring, which may cause the cap layer CAP2 to peel from the surface of the copper wiring W2. It is presumed that the stress increases when the metal wiring and the insulating film are arranged in the horizontal direction and the surface is covered with another insulating film.

  Accordingly, the present inventor has considered reducing the wiring height that substantially causes the occurrence of distortion in the wiring pattern side wall portion in contact with the interlayer insulating film. More specifically, a strain relaxation region is provided outside the wiring pattern side wall. In the strain relaxation region, the lower part is a peripheral insulating film, and the upper part is an overhanging wiring region in which the wiring continuously protrudes from the wiring pattern. Since the overhang wiring region has a reduced thickness, a change in height (thermal expansion amount, thermal contraction amount) caused by a temperature change is also reduced.

  As shown in FIG. 3A, the trench TR having a step shape is etched in the interlayer insulating film ID. When the total depth of the trench is t, the sidewall rises from the lower surface to a height of (t−h), protrudes to the outside by a width L, and then rises for the remaining height h. After the copper wiring W is buried in the trench TR and unnecessary portions are removed by CMP, an insulating cap layer CAP having a copper diffusion preventing function is deposited, and an interlayer insulating film ID is further deposited thereon. An extended wiring region EXW having a width L and a height h is formed outside the main wiring region MW having the total thickness t, and constitutes a strain relaxation region RL.

  In the strain relaxation region RL, the overhang wiring region EXW having a thickness h is disposed on the interlayer insulating film having a thickness (t−h). Since the interlayer insulating film having a thickness (t−h) is the same material as the outer interlayer insulating film, the amount of thermal contraction (thermal expansion amount) due to temperature change is the same as that of the outer interlayer insulating film. The overhanging wiring region EXW having a thickness h is larger in height change due to temperature change than the outer interlayer insulating film, for example, the thermal contraction rate due to temperature drop, but the thickness h is smaller than the total thickness t of the wiring. The absolute value of the change is small. By selecting the thickness h, the amount of thermal expansion and heat shrinkage can be reduced to a desired value. Therefore, for example, the amount of surface drop due to the temperature drop in the overhang wiring region EXW having the width L is reduced. The main wiring region MW having the total thickness t is continuous with the overhanging wiring region EXW having the width L and forms a continuous surface. Thus, a sudden change in surface height will not occur. When the insulating cap layer CAP is formed so as to cover the wiring W and the interlayer insulating film ID, the strain received by the insulating cap layer CAP is expected to be small.

  FIG. 3B is a cross-sectional view showing a wiring structure based on this idea. A trench TR having an overhanging portion that extends outward in a stepped manner at the top is formed in the interlayer insulating film ID by two etchings. Let t be the total depth of the trench. Let L be the width of the overhang and h be the height. A barrier metal film BM is deposited by sputtering, for example, with a thickness of 20 nm and a copper seed layer is deposited with a thickness of, for example, 50 nm so as to cover the trench surface, and copper is deposited by plating to the depth of the trench. The unnecessary metal layer on the interlayer insulating film ID is removed by CMP. Hereinafter, since the thickness of the barrier metal film BM is very small, it is ignored. A main wiring region MW is formed in the trench main portion having the total depth t, and an overhanging wiring region EXW is formed in the overhanging portion of the trench continuous outside.

  As an example, the wiring thickness t of the main wiring region MW is 3300 nm. The wiring height h of the overhang wiring area EXW is set to 330 nm with 10% of the thickness t of the main wiring area MW. The width L of the overhang wiring region EXW is 100 nm for the model M5 and 300 nm for the model M6. The stress intensity factors described above were calculated for these models.

  FIG. 4A is a graph showing the stress intensity factors κi of the models M5 and M6 with respect to the width L where the width L of the overhang wiring region EXW is 100 nm and 300 nm. The stress intensity factors κi of the models M1 to M4 with the width L = 0 shown in FIG. 1C are also shown. Models M4 to M6 show the stress intensity factor κi when t = 3300 nm and the width L of the overhang wiring region EXW having the height h = 300 nm is 0, 100, 300 (nm). As the width L increases, the stress intensity factor κi decreases. The stress intensity factor κi of M5 at t = 3300 nm and L = 100 nm is smaller than the stress intensity factor κi of M3 at t = 2400 nm and L = 0 nm. The stress intensity factor κi of M6 at t = 3300 nm and L = 300 nm is smaller than the stress intensity factor κi of M2 at t = 1500 nm and L = 0 nm. When compared with M4 with the same wiring thickness t = 3300 nm and L = 0 (nm), the amount of decrease in κi at M6: L = 300 nm is larger than three times the amount of decrease in κi at M5: L = 100 nm, It shows that it is preferable that the width L of EXW is larger than 100 nm, for example, 150 nm or more.

  The stress intensity factor was also calculated when the height h of the overhang wiring area EXW was 20% of the thickness t of the main wiring area, ie 660 nm.

  FIG. 4B is a model in which the stress intensity factor κi of the models M7 and M8 is set to 330 nm, where the height h of the extended wiring region EXW is 660 nm, and the width L of the extended wiring region EXW is 100 nm and 300 nm. It is a graph shown together with the stress intensity factor κi of M5 and M6. It is shown that when the height h of the overhang wiring region EXW is increased, the stress intensity factor κi increases and the stress relaxation effect decreases. When the height h of the overhang wiring region EXW is 330 nm, the stress intensity factor decreases greatly when the width L is increased from 100 nm to 300 nm. However, when the height h is increased to 660 nm, the width L is increased from 100 nm to 300 nm. However, the decrease in the stress intensity factor obtained by increasing the value is small. If the height of the overhang wiring region is further increased, the obtained effect is expected to be further reduced. The change in the stress intensity factor when the height h of the overhang wiring region EXW was further changed was examined.

  FIG. 4C is a graph showing changes in the stress intensity factor when the width L of the overhang wiring region EXW is 100 nm and the height h is 150 nm (M9), 330 nm (M5), 660 nm (M7), and 900 nm (M10). It is. The horizontal axis indicates the height h (nm) of the overhang wiring region EXW, and the vertical axis indicates the stress intensity factor. Assuming a straight line connecting the stress intensity factors of the models M5 and M7, the stress intensity factor of the model M10 having the increased height h is higher than the straight line (linear approximation), and the stress intensity factor of the model M9 having the decreased height h is reduced. Becomes lower than the straight line (linear approximation). When the height h is increased, the tendency of the strain relaxation effect to increase is strengthened, and when the height h is decreased, the tendency of the strain relaxation effect to increase is increased.

  It may be preferable for strain relief to suppress the height h of the overhang wiring region to a certain level. However, if the height of the overhanging wiring region is reduced, the function as wiring is reduced, which may not be preferable from the viewpoint of utilization efficiency of the substrate area.

Whether or not peeling actually occurs on the copper wiring depends on whether or not the interface has an adhesive property that can face the calculated stress intensity factor. That is, realistic limit values depend on the process and material used. When a process with very high adhesion was used, the peeling phenomenon could be avoided without providing an overhanging wiring region at a copper wiring height of 2400 nm. The height 2400 nm of the copper wiring without a step corresponds to the stress intensity factor κi = 1.537E8 Pa / μm ² as shown in FIGS. 1C and 4A.

  If this value is used as a guideline for the critical value at which the peeling phenomenon occurs, it is considered that FIG. 4A shows that the peeling phenomenon can be avoided by setting the width L of the overhang wiring region to 100 nm or more. If the width L is 150 nm or more, a stable yield can be expected even with respect to manufacturing process deviations. It is considered that the wiring having a thickness of 600 nm does not peel off, and FIGS. 4B and 4C show that the peeling phenomenon can be avoided if the height h of the overhanging wiring region is set to 660 nm or less.

An embodiment based on the above examination results will be described below.
Example 1
FIG. 5A shows the structure of the upper layer wiring of the semiconductor device according to the first embodiment. A one-stage overhang wiring region is provided on the side wall of the damascene wiring. A SiC film is formed as a base insulating film LD on a silicon substrate on which a plurality of transistors are formed and a lower structure LS including lower layer wiring. An SiO ₂ film 11 and an SiC film 12 are laminated on the base insulating film LD to constitute an interlayer insulating film. A trench for accommodating a wiring pattern is formed by etching the SiC film 12 and the SiO ₂ film 11. The trench has an overhanging portion outside the main trench. A barrier metal film 14 and a copper wiring layer 15 are buried in the trench to constitute a copper wiring. The copper wiring has a main wiring region MW having a thickness t of 3300 nm and an extended wiring region EXW formed continuously outside the main wiring region MW and having a height h of 330 nm and a width L of 300 nm. A SiC film 16, SiO ₂ film 17, and SiN film 18 are laminated so as to cover the copper wiring and the interlayer insulating film. In the prepared sample, the width of the main wiring region was 10 μm and the wiring length was 100 μm.

  5B-5H illustrate an example of a manufacturing process of the semiconductor device illustrated in FIG. 5A.

As shown in FIG. 5B, a SiC film having a thickness of 50 nm is formed as a base insulating film LD on the lower structure LS. An SiO ₂ film 11 having a thickness of 3200 nm and an SiC film 12 having a thickness of 100 nm are formed on the base insulating film LD by chemical vapor deposition (CVD).

As shown in FIG. 5C, a resist mask RM1 having an opening with a width of 10.6 μm is formed on the substrate, the SiC film 12 has a total thickness of 100 nm, dry-etched, and the SiO ₂ film 11 has a depth of 230 nm. Control etch by controlled dry etching. The depth of the formed trench is 330 nm. Thereafter, the resist mask RM1 is removed.

As shown in FIG. 5D, a resist mask RM2 having an opening with a width of 10 μm and a width of 300 nm on both sides of the opening of the resist mask RM1 is formed on the substrate. Using the resist mask RM2 as an etching mask, the remaining thickness of the SiO ₂ film 11 is dry-etched. Thereafter, the resist mask RM2 is removed. A trench having a protruding portion having a width of 300 nm and a height of 330 nm is formed on both sides of a central portion having a depth of 3300 nm and a width of 10 μm.

  As shown in FIG. 5E, a Ta film 14 having a thickness of about 20 nm on the flat portion is formed as a barrier metal film by sputtering, and a Cu film 15S having a thickness of about 20 nm on the flat portion is formed thereon as a plating seed layer. Form a film. Sputtering is performed at a substrate temperature of room temperature.

  As shown in FIG. 5F, a Cu film is electrolytically plated on the Cu film 15S to obtain a copper layer 15. The copper layer 15 is electroplated to have a thickness that completely fills the trench. A heat treatment at 100 ° C. to 350 ° C. is performed to perform grain growth in the Cu film.

  As shown in FIG. 5G, the copper layer 15 above the surface of the SiC film 12 is removed by chemical mechanical polishing (CMP). A copper wiring having an overhanging wiring area EXW is formed outside the main wiring area MW. The main wiring region MW and the overhanging wiring region EXW outside thereof have a surface flush with the surface of the SiC film 12.

As shown in FIG. 5H, on the substrate covering the Cu film 15 and the SiC film 12, an SiC film 16 having a thickness of 50 nm as an insulating copper diffusion preventing film, an SiO ₂ film 17 having a thickness of 500 nm as an upper insulating film, and passivation. A 50 nm thick SiN film 18 is formed as a film by CVD. Thereafter, if necessary, an opening is formed in the insulating film on the copper wiring, an Al film is formed by etching using a resist mask, and a pad serving as a terminal is formed. At this time, heat treatment is performed at 400 ° C. for 30 minutes. In this way, the upper wiring is formed.

  According to this example, this example sample was prepared. A comparative example sample without an overhang wiring area EXW was also created. The comparative example is the same as the sample of this example except that it does not have an overhanging wiring region.

  The reliability test of the created wiring was performed. An electromigration test was performed at a temperature of 250 ° C. and a current density of 1 MA / cm 2. After the test for 200 hours, no failure occurred in either the sample of the present example or the sample of the comparative example. However, in the comparative example, there was one in which the resistance slightly changed. When the failure analysis was performed on the sample with the resistance changed, it was found that peeling occurred at the interface between the Cu film and the SiC film thereon. The sample of this example had no change in resistance, and as far as examined, there was no peeling at the interface.

In the above embodiment, the SiO ₂ film as the main insulating film is formed by CVD, but other vapor phase methods, liquid phase coating methods such as SOD (spin-on deposition), etc. may be used. Although the SiO ₂ film is used as the main insulating film, other insulating materials can be used. For example, SiN or SiCN having a higher dielectric constant than SiO ₂ may be used in order to improve the performance as inductance. The same material as the insulating film of the lower wiring, for example, SiOC having a dielectric constant lower than that of SiO ₂ may be used. Although Ta is used as the barrier metal film, a TaN film, a stacked layer of Ta film and TaN film, or the like may be used. In addition, various changes and substitutions are possible.
(Example 2)
In Example 1, the step portion of the trench was formed by control etching. If the etch stopper structure is used, the step structure can be formed more easily and stably.

FIG. 6A shows the structure of the upper layer wiring of the semiconductor device according to the second embodiment. Similar to the first embodiment, a SiC film is formed as a base insulating film LD on a silicon substrate on which a plurality of transistors are formed and a lower structure LS including lower layer wiring. An SiO ₂ film 21 having a thickness of 3000 nm and a SiN film 22 having a thickness of 330 nm functioning as a hard mask are laminated on the base insulating film LD to constitute an interlayer insulating film. A trench in which a step is formed at the interface between the SiN film 22 and the SiO ₂ film 21 is formed. The protruding portion of the trench is formed by etching the SiN film 22 and has the same height h = 330 nm as the thickness of the SiN film 22. Similar to the first embodiment, the barrier metal film 14 and the copper wiring layer 15 are buried in the trench to form a copper wiring. The copper wiring has a main wiring region MW having a thickness t of 3.3 μm and an overhanging wiring region EXW which is continuously formed on the outside thereof and has a height h of 330 nm and a width L of 300 nm. The side surface of the extended wiring region EXW is in contact with only the SiN film 22. A cap film 26 formed of a SiC film having a thickness of 70 nm having a copper diffusion preventing function, a SiO ₂ film 27 having a thickness of 500 nm, and a SiN film 28 having a thickness of 50 nm are laminated so as to cover the copper wiring and the SiN film 22. Yes. As in Example 1, an opening is formed in the insulating film, and an Al terminal is formed.

  6B-6F show an example of a manufacturing process of the semiconductor device shown in FIG. 6A.

As shown in FIG. 6B, an SiC film having a thickness of 50 nm is formed as a base insulating film LD on the lower structure LS. On the base insulating film LD, a 3000 nm thick SiO ₂ film 21 and a 330 nm thick SiN film 22 are formed by chemical vapor deposition (CVD). The SiO ₂ film 21 and the SiN film 22 have different etching characteristics, and the SiO ₂ film can be used as an etch stopper in etching the SiN film.

As shown in FIG. 6C, a resist mask RM3 having an opening with a width of 10 μm is formed on the substrate, and the entire thickness of 330 nm of the SiN film 22 is etched by wet etching using hot phosphoric acid as an etchant. The SiO ₂ film 21 is not etched with hot phosphoric acid, and the etching is automatically stopped. Since the SiN film 22 is continuously etched by wet etching, a smooth side surface can be obtained. Thereafter, the resist mask RM3 is removed.

As shown in FIG. 6D, the SiO ₂ film 21 is dry-etched using the etched SiN film 22 as a hard mask. Although a resist mask is not used, the etching itself is the same as the dry etching of FIG. 5D.

As shown in FIG. 6E, a resist mask RM4 having an opening with a width of 10.6 μm, which is 300 nm wider on both sides than the opening of the resist mask RM3, is formed on the substrate. In the opening, the SiN film 22 having a width of 300 nm is exposed on both sides. The SiN film 22 is etched by wet etching using hot phosphoric acid as an etchant. The SiC film LD and the SiO ₂ film 21 are not etched with hot phosphoric acid. Only the SiN film 22 is etched to form a trench overhang. If there is an interface between different layers at the intermediate depth of the overhanging portion as in Example 1, irregularities based on the interface are likely to be formed. In this embodiment, since the single layer is wet-etched, a sharp side surface can be formed without forming irregularities on the side surface. Thereafter, the resist mask RM4 is removed. A step-structured trench having a trench overhanging portion having a width of 300 nm and a height of 330 nm is formed on both sides of a trench central portion having a depth of 3.3 μm and a width of 10 μm.

As shown in FIG. 6F, as in Example 1, a Ta film 14 having a thickness of about 20 nm on the flat portion is formed as a barrier metal film by sputtering. Thereafter, the Cu layer 15 is embedded in the trench by the same process as in the first embodiment. A 50 nm thick SiN film 26 that functions as an insulating copper diffusion prevention film is deposited by CVD on the SiN layer 22 so as to cover the Cu layer 15, and a 500 nm thick SiO ₂ film 27 is deposited thereon by CVD. Then, a 50 nm thick SiN film 28 is deposited.

  According to this example, this example sample was prepared. A comparative example sample without an overhang wiring area EXW was also created. In the prepared sample, the width of the main wiring region was 10 μm and the wiring length was 100 μm. The comparative example is the same as the sample of this example except that it does not have an overhanging wiring region.

  The prepared sample was subjected to a temperature cycle test. The temperature cycle was repeated from −80 ° C. to 125 ° C. In the comparative sample, it was found that peeling occurred at the Cu / SiN interface in approximately 1% of the samples. In this example sample, no peeling at the Cu / SiN interface occurred.

The step structure of the thick wiring side wall is not limited to one step. A step structure having an arbitrary number of steps can be used. Hereinafter, the case of a two-step structure will be described as an example.
(Example 3)
FIG. 7A shows the structure of the upper layer wiring of the semiconductor device according to the third embodiment. A two-stage overhang wiring region is provided on the side wall of the damascene wiring. As in the first embodiment, a SiC film is formed as a base insulating film LD on the lower structure LS, and a SiO ₂ film 11 having a thickness of 3200 nm and a SiC film 12 having a thickness of 100 nm are stacked on the base insulating film LD. Constitutes an interlayer insulating film. The SiC film 12 and the SiO ₂ film 11 are etched to form a trench having a two-step structure on the side wall. The trench has a two-stage projecting portion outside the main trench. The first stage of the overhang portion following the main trench has a width L1 = 150 nm and a height h1 = 330 nm. The second stage following the first stage also has a width L2 = 150 nm and a height h2 = 330 nm. The depth of the first step from the surface is 660 nm.

A barrier metal film 14 and a copper wiring layer 15 are buried in the trench to constitute a copper wiring. The copper wiring has a main wiring region MW having a thickness t of 3300 nm and an extended wiring region EXW having a two-stage structure which is continuously formed on the outer side and has a height h of 330 nm and a width L of 150 nm. A SiC film 16 having a thickness of 50 nm, a SiO ₂ film 17 having a thickness of 500 nm, and a SiN film 18 having a thickness of 50 nm are stacked so as to cover the copper wiring and the interlayer insulating film. The structure of the present embodiment corresponds to a structure in which the one-step structure of the first embodiment is replaced with a two-step structure.

  7B-7F show an example of a manufacturing process of the semiconductor device shown in FIG. 7A.

As shown in FIG. 7B, an SiC film having a thickness of 50 nm is formed as a base insulating film LD on the lower structure LS. An SiO ₂ film 21 having a thickness of 3200 nm and an SiC film 22 having a thickness of 100 nm are formed on the base insulating film LD by chemical vapor deposition (CVD).

As shown in FIG. 7C, a resist mask RM1 having an opening with a width of 10.6 μm is formed on the substrate, the SiC film 12 is dry-etched to a total thickness of 100 nm, and the SiO ₂ film 11 is etched to a depth of 230 nm. Control etch by controlled dry etching. The depth of the formed trench is 330 nm. Thereafter, the resist mask RM1 is removed. The steps up to here are the same as in the first embodiment.

As shown in FIG. 7D, a resist mask RM5 having an opening with a width of 10.3 μm, which is 150 nm narrower on both sides than the opening of the resist mask RM1, is formed on the substrate. Using the resist mask RM5 as an etching mask, the SiO ₂ film 11 is control-etched with a thickness of 330 nm. Thereafter, the resist mask RM5 is removed.

As shown in FIG. 7E, a resist mask RM2 having an opening with a width of 10 μm and a width of 300 nm on both sides of the opening of the resist mask RM1 is formed on the substrate. Using the resist mask RM2 as an etching mask, the remaining thickness of the SiO ₂ film 11 is dry-etched. Thereafter, the resist mask RM2 is removed.

  A trench with a projecting portion having a two-stage trench projecting portion having a width of 150 nm and a height of 330 nm is formed on both sides of the trench central portion having a depth of 3300 nm and a width of 10 μm.

  As shown in FIG. 7F, a Ta film 14 having a thickness of about 20 nm on the flat portion is formed as a barrier metal film by sputtering, and a Cu film having a thickness of about 50 nm on the flat portion is formed thereon as a plating seed layer. Film. Sputtering is performed at a substrate temperature of room temperature. A Cu film is electrolytically plated on the Cu seed film to obtain a copper layer 15. The copper layer 15 is electroplated to have a thickness that completely fills the trench. A heat treatment at 100 ° C. to 350 ° C. is performed to perform grain growth in the Cu film. Thereafter, the structure shown in FIG.

This example sample according to this example and a comparative example sample without an overhang wiring region were prepared. In the prepared sample, the width of the main wiring region was 10 μm and the wiring length was 100 μm. An electromigration test was performed on this sample and the comparative sample. A current of 1.5 MA / cm ² was passed at a temperature of 300 ° C. Compared with the electromigration test of the sample of Example 1, both temperature and current density are more severe conditions. Neither sample failed after 168 hours of testing. However, in the sample of the comparative example, the resistance changed in 10% of the samples, and when the wiring was analyzed for failure, it was found that peeling occurred at the Cu / SiC interface. In the sample of this example, there was no change in resistance, and as far as investigated, there was no peeling at the Cu / SiC interface.

When a conventional wiring without an overhang wiring region was formed, there was a high probability that peeling was found between the copper wiring and the copper diffusion prevention film on the corner where the wiring bent at a right angle. In the corner portion, the wiring is bent at a right angle, and the interface between the side wall of the wiring region and the outer interlayer insulating film is bent at a right angle. Therefore, a complicated stress distribution is generated from the straight portion. Due to these factors, peeling is likely to occur at the corner. Therefore, we examined a structure that devised the wiring corner.
Example 4
FIG. 8A is a plan view illustrating a planar pattern of wiring according to the fourth embodiment. The wiring 15 is connected to the straight portion along the X direction and the straight portion along the Y direction, and the direction is changed by 90 degrees at the bent position. The wiring 15 has a main wiring region MW having a total thickness and an extended wiring region EXW formed continuously outside the main wiring region MW and having a reduced thickness from the top surface to the intermediate depth. The width of the extended wiring area EXW is wider at the bent part of the wiring than at the straight line part of the wiring.

  FIG. 8B shows a cross-sectional structure of the straight wiring portion along the cutting line AB of FIG. 8A. Similar to the cross-sectional structure shown in FIG. 5A, the main wiring region MW has a thickness of 3300 nm and a width of 10 μm, and the overhanging wiring region EXW has a thickness of 330 nm and a width LS of 300 nm.

  FIG. 8C shows a cross-sectional structure of a wiring bent portion (90 degrees) along the cutting line CD in FIG. 8A. The characteristic of the main wiring area MW is the same as that of the straight part. The overlaid wiring region EXW has the same thickness as the rectilinear portion of 330 nm, and the width LC is expanded to 600 nm in both the X and Y directions. The width LC of the overhang wiring region at the bent portion is increased to twice the width LS of the overhang wiring region at the straight portion. By increasing the width of the overhanging wiring region of the bent portion, it is possible to suppress the phenomenon that the bent portion easily peels off.

  A sample of an example according to this example and a comparative sample without an overhang wiring region were prepared, and a temperature cycle test was performed. The wiring shape is a pattern in which two straight portions are connected at an angle of 90 degrees. The temperature cycle was repeated from −80 ° C. to 125 ° C. In the comparative sample, it was found that peeling occurred at the Cu / SiC interface in approximately 1% of the sample.

  In the present embodiment, for the convenience of mask preparation, the extended overhanging wiring region at the wiring bending portion has a rectangular basic shape. The shape of the bent portion and the shape of the enlarged overhang wiring region are not limited to these.

  FIG. 9A shows a case where the shape of the extended wiring region EXW enlarged at the bent portion is circular. 9B and 9C show a configuration in which the wiring is connected in a T shape and the width of the connection portion of the overhang wiring region EXW along different directions is expanded into a circular shape and a rectangular shape. FIGS. 9D and 9E show a configuration in which the wiring intersects and the width of the connection (crossing) portion of the overhang wiring region EXW along different directions is expanded into a circular shape and a rectangular shape.

  When an inductor is formed, a long wiring length may be required, and a loop shape (or a spiral shape) or the like is also used to fit the inductor in a predetermined area.

  10A and 10B show examples of the shape of the inductor wiring.

  FIG. 10A shows a configuration in which linear wirings are connected at 90 degrees to form a rectangular (rectangular) loop wiring. Similar to the fourth embodiment, the width of the overhanging wiring region in the connection portion is enlarged in a rectangular shape. Even in the case where the wirings are arranged in a triangular shape, an effect of suppressing peeling may be obtained by providing an overhanging wiring region in the connection portion. When forming a polygonal wiring, increasing the width of the overhanging wiring region of the connecting portion will be effective in suppressing peeling.

  FIG. 10B shows a configuration in which straight wirings are connected at an obtuse angle to form an octagonal loop wiring. The width of the overhanging wiring region in the connection portion is enlarged in a circular shape. It is expected that as the angle of the connecting portion becomes obtuse, it becomes closer to a straight line and is less likely to peel off.

  Increasing the capacity of the inductor can be achieved not only by increasing the thickness of the wiring, but also by increasing the dielectric constant of the surrounding insulating film. For example, it is conceivable to use silicon nitride having a higher dielectric constant instead of silicon oxide.

FIG. 11A shows an interlayer insulating film structure in which a hard mask film 33 such as a SiN film 31, a SiO ₂ film 32, or SiN is stacked on a base insulating film ID that covers the lower structure LS. Similar to the second embodiment, a material having different etching characteristics is used as an etch stopper, so that a step is formed at the interface between the different materials, and a two-stage overhang wiring structure is formed as in the third embodiment.

FIG. 11B shows that a high dielectric constant insulating film 41 having a relative dielectric constant ε = 10 to 12 including metal nanodots is formed by simultaneously sputtering SiO ₂ and FePt on the base insulating film ID covering the lower structure LS. Forming. A hard mask film 42 such as SiN or SiC is formed on the high dielectric constant insulating film 41, and an interlayer insulating film is formed together with the high dielectric constant insulating film 41. It is also possible to obtain an etch stopper function similar to that of the second embodiment.

The wiring material is not limited to copper, and Al and Al alloys are also used. When compared with insulating materials, metals such as Al also have a large difference in thermal expansion coefficient. When a thick wiring is surrounded by an insulating film, stress based on a difference in thermal expansion coefficient is applied, which may cause peeling. By providing an overhanging wiring area outside the main wiring area, an effect of alleviating strain based on the difference in thermal expansion coefficient can be expected.
(Example 5)
FIG. 12A shows the structure of the Al wiring. On the silicon substrate on which a plurality of transistors are formed and the lower structure LS including the lower layer wiring, a TiN barrier metal film 57 having a thickness of 50 nm, an Al film 58 having a thickness of 3300 nm, and a TiN barrier metal film having a thickness of 50 nm are stacked. Wiring is formed. The cross-sectional shape of the Al wiring has a main wiring region MW having a rectangular cross section and an overhanging wiring region EXW that continuously extends outward from the main wiring region MW in the same manner as the above-described embodiment. The overhang wiring region EXW has a width of 300 nm, for example. It has a height of 330 nm. An insulating film 51 such as SiO ₂ is formed so as to surround the Al wiring.

  12B-12G illustrate an example of a manufacturing process of the semiconductor device illustrated in FIG. 12A.

  As shown in FIG. 12B, a 50 nm thick TiN film 57 and a 3 μm thick Al film 58-1 are formed on the lower structure LS by sputtering. A resist mask RM6 having a planar shape of the main wiring region having a width of 10 μm is formed on the Al film 58-1. Using the resist mask RM6 as an etching mask, the Al film 58-1 and the TiN film 57 are patterned by dry etching or the like. Thereafter, the resist mask RM6 is removed.

As shown in FIG. 12C, an SiO ₂ film 51-1 is deposited on the entire surface of the substrate by plasma CVD or the like, and the patterned Al film 58-1 and TiN film 57 are covered.

As shown in FIG. 12D, the SiO ₂ film 51-1 is polished by chemical mechanical polishing (CMP) to expose the surface of the Al film 58-1 and planarize the surface.

  As shown in FIG. 12E, an Al film 58-2 having a thickness of 330 nm and a TiN film 59 having a thickness of 50 nm are deposited on the substrate by sputtering. On the TiN film 59, a resist mask RM7 having a contour of an extended wiring region having a width of 10.6 μm is formed. Using the resist mask RM7 as an etching mask, the TiN film 59 and the Al film 58-2 are patterned by dry etching or the like. Thereafter, the resist mask RM7 is removed.

  As shown in FIG. 12F, an Al wiring having an overhang region at the top is formed. The overhang wiring region is formed of a TiN film 59 and an Al film 58-2. In the main wiring region, an Al film 58 is formed by the lower Al film 58-1 and the upper Al film 58-2, and TiN films 57 and 59 are laminated on the upper and lower sides thereof.

As shown in FIG. 12G, a SiO ₂ film 51-2 is deposited by plasma CVD or the like so as to enclose the patterned TiN film 57 and Al film 58-1. The lower SiO ₂ film 51-1 and the upper SiO ₂ film 51-2 form the SiO ₂ film 51 that wraps the wiring.

  An example sample according to this example was prepared together with a comparative example sample having no overhang wiring region, and a temperature cycle test was performed.

  FIG. 12H is a cross-sectional view illustrating a configuration of a sample of a comparative example.

  The temperature cycle was repeated from −80 ° C. to 125 ° C. In the comparative sample, peeling occurred on the Al side surface in approximately 0.1% of the sample. In the sample of this example, no peeling occurred on the upper surface or the side surface without the barrier metal.

  The Al wiring is aligned with the insulating layer on the upper surface of the base insulating layer. From these relationships, it is considered that the upper surface of the copper wiring corresponds to the bottom surface of the Al wiring. Instead of providing the overhanging wiring area outside the upper surface of the main wiring area, it is considered that the same effect can be obtained by providing the overhanging wiring area outside the bottom surface.

FIG. 13 shows another structure of the Al wiring. On the base structure LS, an Al wiring is formed by stacking a TiN barrier metal layer 57 having a thickness of 50 nm, an Al film 58 having a thickness of 3.3 μm, and a TiN barrier metal film having a thickness of 50 nm. The cross-sectional shape of the Al wiring has a main wiring region MW having a rectangular cross section and an overhanging wiring region EXW that continuously extends to the bottom thereof. The overhang wiring region EXW has a width of 300 nm, for example. It has a height of 330 nm. An insulating film 52 such as SiO ₂ is formed so as to surround the Al wiring. In the case of this structure, a TiN film 57, an Al film 58, and a TiN film 59 are continuously formed, and the shape of the main wiring region is defined by performing control etching from above, and a resist mask having an increased width is formed. The shape of the overhang wiring region can be defined. There is no need to divide the film forming process.

  FIG. 14 shows a configuration example of a semiconductor integrated circuit device. An element isolation region 102 is formed on the Si substrate 101, and a large number of active regions are defined. An n channel MOS transistor and a p channel MOS transistor are formed in the active region. A layer including the transistor is referred to as a transistor layer TR. A multilayer interlayer insulating film is formed on the transistor layer TR, and the multilayer wiring is disposed therein. When the multilayer wiring is divided into the lower layer wiring WR1, the middle layer wiring WR2, and the upper layer wiring WR3, the upper layer wiring has a wider wiring width, a thicker wiring thickness, and a lower wiring pitch. Lower layer wiring and middle layer wiring are formed by copper wiring, and upper layer wiring is formed by copper wiring and Al wiring. The wiring according to the above-described embodiment is mainly used for the upper layer wiring.

 As mentioned above, although this invention was demonstrated along the Example, this invention is not restrict | limited to these. It will be apparent to those skilled in the art that various modifications, substitutions, improvements, combinations, and the like can be made.

  The features of the present invention will be described below.

(Appendix 1)
A semiconductor substrate;
An insulating film formed above the semiconductor substrate;
A main wiring region having a first thickness formed in the insulating film;
Forming one or more steps from the side wall of the main wiring region and projecting outward, the projecting wiring region having a second thickness smaller than the first thickness;
A semiconductor device.

(Appendix 2)
The semiconductor device according to claim 1, wherein the overhang wiring region has an upper surface flush with the main wiring region.

(Appendix 3)
The semiconductor device according to appendix 1 or 2, wherein a barrier metal film is provided between the insulating film and the main wiring region.

(Appendix 4)
4. The semiconductor device according to any one of appendices 1 to 3, further comprising a barrier metal film between the insulating film and the extended wiring region.

(Appendix 5)
The semiconductor device according to any one of appendices 1 to 4, further comprising an insulating cap layer formed on the main wiring region and the overhanging wiring region.

(Appendix 6)
The semiconductor device according to any one of appendices 1 to 5, wherein the main wiring region and the overhanging wiring region are made of a material containing copper.

(Appendix 7)
The semiconductor device according to claim 1, wherein the first thickness is 600 nm or more.

(Appendix 8)
The semiconductor device according to any one of appendices 1 to 7, wherein the second wiring region has a second thickness of 660 nm or less.

(Appendix 9)
9. The semiconductor device according to any one of appendices 1 to 8, wherein a protruding amount of the protruding wiring region is 150 nm or more.

(Appendix 10)
The main wiring region has a planar shape in which a plurality of linear portions are connected at a connection position, and the amount of the extension of the extension wiring region is larger than the other positions around the connection position. Semiconductor device.

(Appendix 11)
11. The semiconductor device according to appendix 10, wherein the overhanging wiring region around the connection position has a square or arc-shaped planar shape.

(Appendix 12)
12. The semiconductor device according to any one of appendices 1 to 11, wherein the main wiring region and the overhanging wiring region constitute a generally rectangular or octagonal inductor as a whole.

(Appendix 13)
The semiconductor device according to appendix 12, wherein the insulating film includes metal fine particles.

(Appendix 14)
A main wiring region having a first thickness and extending in the insulating film above the semiconductor substrate substantially parallel to the surface of the semiconductor substrate, having a planar shape including connection regions with wirings or pads of different levels; Forming one or more steps from the side wall of the main wiring region and projecting outward to form a projecting wiring region having a second thickness smaller than the first thickness;
A method for manufacturing a semiconductor device.

(Appendix 15)
The step of forming the main wiring region and the overhanging wiring region forms an interlayer insulating film, forms a wiring trench whose wiring width is increased stepwise on the interlayer insulating film, and forms a barrier metal on the surface of the wiring trench. Forming a layer, forming a wiring layer made of a material containing copper on the barrier metal layer, removing an unnecessary metal layer on the interlayer insulating film, and forming the main wiring region and the overhanging wiring region in the trench Including the process of leaving
15. The method of manufacturing a semiconductor device according to appendix 14, further comprising a step of forming an insulating cap layer having a copper diffusion preventing function on the main wiring region, the overhanging wiring region, and the interlayer insulating film.

(Appendix 16)
The step of forming the main wiring region and the overhanging wiring region includes forming a lower wiring pattern on a lower interlayer insulating film, covering the lower wiring pattern, forming a lower insulating film, and removing the lower insulating film from above. Removing and exposing the lower wiring pattern, forming an upper wiring pattern having a wiring width wider than the lower wiring pattern on the lower wiring pattern, and forming an upper insulating film covering the upper wiring pattern,
15. A method for manufacturing a semiconductor device according to appendix 14.

Claims (11)

A semiconductor substrate;
A first insulating cap layer formed above the semiconductor substrate;
An interlayer insulating film formed above the first insulating cap layer and including a via hole and a trench on the via hole, the trench having a step-shaped side wall above the via hole;
Via conductors formed in the via holes;
A wiring formed in the trench, the wiring having a different cross-sectional shape from the via conductor;
A second insulating cap layer formed above the interlayer insulating film;
Including
Here, the wiring above the via is provided above the via, and has a main portion having a first thickness exceeding 660 nm, and a second portion that is provided across the main portion and is thinner than the first thickness. And a projecting portion that projects out from the side portion of the main portion to the outside by 150 nm or more , and
The material of the interlayer insulating film is a semiconductor device different from the material of the first insulating cap layer and the material of the second insulating cap layer.   The semiconductor device according to claim 1, wherein the protruding portion is formed on both sides of the main portion.   The semiconductor device according to claim 1, further comprising a barrier metal film formed between the interlayer insulating film and the wiring.   The semiconductor device according to claim 1, wherein the wiring contains copper.   The semiconductor device according to claim 1, wherein the second thickness is 660 nm or less.   The semiconductor device according to claim 1, wherein the wiring forms an inductor.   The interlayer insulating film includes a first insulating film and a second insulating film, wherein the first insulating film is in contact with a side surface of the main portion, and the second insulating film is in contact with a side surface of the projecting portion. The semiconductor device described. The semiconductor device according to claim 7 , wherein the first insulating film and the second insulating film have different etching characteristics.   The protruding portion in cross-sectional view has a step shape, has first and second sub-portions, the first sub-portion has a third thickness, and the second sub-portion has a fourth thickness. Each of the third and fourth thicknesses is thinner than the first thickness, the first sub-portion projects outward from the side of the main portion, and the second sub-portion is The semiconductor device according to claim 1, wherein the semiconductor device projects outward from a side portion of one sub-portion. A semiconductor substrate;
A first insulating cap layer formed above the semiconductor substrate;
An interlayer insulating film formed above the first insulating cap layer and including a via hole and a trench on the via hole, the trench having a step-shaped side wall above the via hole;
Via conductors formed in the via holes;
A wiring formed in the trench, the wiring having a different cross-sectional shape from the via conductor;
A second insulating cap layer formed above the interlayer insulating film;
Including
Here, the wiring above the via is provided above the via and has a first portion having a first thickness, and a second thickness that is provided across the main portion and is thinner than the first thickness. And a projecting portion that projects outward from the side of the main portion, and
The material of the interlayer insulating film is different from the material of the first insulating cap layer and the material of the second insulating cap layer,
The wiring has a plurality of linear portions and at least one corner portion connecting the linear portions, and the amount of the protruding portion corresponding to the protruding portion in the corner portion corresponds to the protruding portion in the linear portion. A semiconductor device larger than the amount protruding from the main part. The semiconductor device according to claim 10 , wherein a planar shape of the projecting portion included in the corner portion has a square shape or an arc shape.

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