JP4670578B2 - Method for forming inclined surface, wiring structure and method for forming the same, covering layer of step structure, and semiconductor device - Google Patents

Description

  The present invention relates to a method of forming an inclined surface formed on a stepped portion provided on a substrate, a wiring structure straddling the stepped portion using the inclined surface, a method of forming the same, a covering layer of the stepped structure, and the wiring The present invention relates to a semiconductor device including a structure.

  In a semiconductor device such as an integrated circuit, a wiring that electrically connects the upper and lower stages of the stepped part may be required. For example, when a light-receiving diode or a laser diode, which is an element formed in a mesa shape, is used, the upper surface (upper stage) of the element and the substrate surface (lower stage) must be electrically connected.

As such wiring, so-called air bridge wiring is known (for example, refer to FIG. 1 of Patent Document 1).
JP 2004-103819 A

  In the technique disclosed in Patent Document 1, a pillow-shaped support that connects the upper and lower steps of the step with a gentle inclination is formed of a photoresist, and a metal is vacuum-deposited on the support to form a step. Wiring (air bridge wiring) that connects the upper and lower stages of the upper layer is formed.

  Hereinafter, the air bridge wiring forming method disclosed in Patent Document 1 will be described while supplementing with a conventionally known technique.

  First, as shown in FIG. 14A, a support 106 that connects the upper stage 102 and the lower stage 104 of the step 100 is formed of a first photoresist. That is, photolithography is performed on the first photoresist applied to the entire surface of the substrate 112 including the step 100. Thereby, the support body 106 made of the first photoresist is formed. The support 106 is formed with an inclined surface 110 having a gentler inclination than the side surface 108 (extending substantially vertically) of the step 100.

  Next, although not shown in the drawing, the planar region excluding the region including the inclined surface 110 of the support 106 (scheduled wiring formation region) is covered with the second photoresist. As a result, a resist pattern in which only the wiring formation scheduled region (stretching between the upper stage 102 and the lower stage 104) is exposed is formed.

  Then, a metal film to be the wiring 113 is deposited with a predetermined film thickness by vacuum deposition on the entire surface of the second photoresist and the wiring formation scheduled region. Thereafter, the unnecessary metal film on the second photoresist is removed (lifted off) together with the second photoresist.

  As a result, as shown in FIG. 14B, a wiring 113 in which a metal film is deposited in a predetermined film thickness is formed in the wiring formation scheduled region including the slope 110 of the support 106.

  However, with this prior art, it has been difficult to make the slope 110 sufficiently gentle. For this reason, during vacuum deposition, the metal film often breaks as described later. As a result, the wiring 113 is disconnected due to disconnection, and there is a problem that the manufacturing yield of a semiconductor device using the wiring 113 is lowered.

  Here, with reference to FIG. 15 (A) and (B) and FIG. 16 (A)-(E), the mechanism of generation | occurrence | production of a step break in a metal film is demonstrated.

  As shown in FIG. 15A, a case where a metal film 120 is deposited on a deposition target surface 128 of a model structure 118 using a vacuum deposition apparatus 119 is considered. The vacuum deposition apparatus 119 is configured to rotate the model structure 118 with respect to the metal evaporation source 116 in order to deposit the metal film 120 on the deposition target surface 128 with a uniform film quality.

  Therefore, as shown in FIG. 15B, when viewed from an arbitrary point P on the deposition surface 128, the incident direction of the metal atoms flying toward the deposition surface 128 is periodically within a certain angle range β. Vibrate.

  Here, the outermost direction in the vibration range of the incident direction is referred to as an incident direction A and an incident direction C. An incident direction between the incident directions A and C and perpendicular to the deposition surface 128 is referred to as an incident direction B. The acute angle side of the angle formed by the incident direction A and the surface on which the deposition surface 128 extends is denoted by λ, and this angle λ is referred to as the incident angle of the incident direction A. Similarly, the acute angle side of the angle formed by the incident direction C and the surface on which the deposition surface 128 extends is denoted by λ ′, and this angle λ ′ is referred to as the incident angle in the incident direction C.

  With reference to FIGS. 16A to 16E, a process of depositing the metal film 120 on the model structure 118 under the above-described conditions will be described.

  First, the configuration of the model structure 118 will be briefly described with reference to FIG.

  The model structure 118 includes an upper flat surface 122, a lower flat surface 124, and a slope 126 as the deposition surface 128.

  The upper flat surface 122 and the lower flat surface 124 extend in parallel to each other. The inclined surface 126 gently connects the two flat surfaces 122 and 124.

  It is assumed that the inclination angle τ of the inclined surface 126 is larger than the incident angle λ described above (τ> λ).

(Step 1: (FIG. 16A))
First, consider a case where metal atoms fly from the incident direction A (arrow in the figure) to the model structure 118.

  In this case, since τ> λ, the metal atoms flying from the incident direction A cannot be deposited in a region (hereinafter referred to as a shadow region) N1 which is a shadow of the upper plane surface 122. As a result, the metal film 120 a is deposited only on the upper flat surface 122 and the lower flat surface 124.

(Stage 2: (FIG. 16B))
After stage 1, the model structure 118 rotates by a predetermined angle with respect to the evaporation source 116. Thereby, the metal atoms fly to the model structure 118 from the incident direction B (arrow in the figure).

  In this case, the metal atoms are incident perpendicular to the lower plane 124 (upper plane 122). As a result, the metal film 120b is deposited on the entire vapor deposition surface 128.

(Stage 3: (FIG. 16C))
After stage 2, the model structure 118 rotates by a predetermined angle with respect to the evaporation source 116. Thereby, the metal atoms fly to the model structure 118 from the incident direction C (arrow in the figure).

  In this case, metal atoms cannot be deposited in the shadow region N2 of the edge 120bE of the metal film 120b deposited on the lower flat surface 124. As a result, the metal film 120c is deposited on the vapor deposition surface 128 excluding the shadow region N2.

(Step 4: (FIG. 16D))
After stage 3, the model structure 118 rotates by a predetermined angle with respect to the evaporation source 116. Thereby, the metal atoms fly to the model structure 118 from the incident direction B (arrow in the figure).

  In this case, the metal atoms are incident perpendicular to the lower plane 124 (upper plane 122). As a result, the metal film 120d is deposited on the entire vapor deposition surface 128.

(Step 5: (FIG. 16E))
After stage 4, the model structure 118 rotates a predetermined angle with respect to the evaporation source 116. Thereby, the metal atoms fly to the model structure 118 from the incident direction A (arrow in the figure).

  In this case, metal atoms cannot be deposited in the shadow region N2 of the edge 120dE of the metal film 120d deposited on the upper flat surface 122. As a result, the metal film 120e is deposited on the vapor deposition surface 128 excluding the shadow region N2.

  After Step 5, the metal film 120 is deposited by repeating Steps 1 to 5 described above.

  Here, attention is paid to the variation in the deposition surface 128 of the film thickness of the metal film 120 after the step 5. Then, it can be seen that the metal film 120 in the shadow region N2 is significantly thinner than the other regions. This is because in the shadow region N2, the metal films 120b and 120d are deposited only in two of the five steps (steps 2 and 4).

  Further, it can be seen that the metal film 120d existing in the shadow region N2 is not maintained in continuity with the metal film 120d in the region other than the shadow region N2. That is, in the shadow region N2, grain boundaries GB1 and GB2 are formed between the metal films 120d and 120b and between the metal films 120d and 120c, respectively. Thus, when the continuity of the metal film 120d is not maintained, the electrons flowing through the metal film 120 must pass through the grain boundaries GB1 and GB2, so that the electrical resistance increases.

  That is, in the shadow region N2, the thickness of the metal film 120 is relatively thin compared to other regions, and the continuity of the metal film 120 is not maintained. These phenomena occurring in the shadow region N2 are collectively referred to as “step breakage”.

  From the consideration of the mechanism described above, it can be seen that the cause of the step break is that the inclination angle τ of the slope 126 is larger than the incident angle λ of the metal atoms. That is, in each of the stages 1, 3, and 5, the fact that metal atoms are not deposited on the entire surface to be vapor-deposited 128 is a cause of the occurrence of the stage break.

  Note that step breakage may occur even when the model structure 118 is stationary. This is because the evaporation source 116 cannot be regarded as a point evaporation source. That is, the metal atoms flying from the evaporation source 116 to the deposition surface 128 have an incident angle distribution corresponding to the area of the evaporation source 116. Therefore, depending on the incident angle of the metal atoms with respect to the deposition surface 128, a shadow region similar to the above is generated on the deposition surface 128. As a result, breakage occurs by the same mechanism as described above.

  From the above description, it can be seen that it is effective to reduce the inclination angle τ of the slope 126 in order to prevent the occurrence of step breaks.

  As a measure for this, it is conceivable to use a high-viscosity photoresist as the first photoresist for forming the support 106 (FIG. 14). If the high-viscosity first photoresist is used, the inclination angle of the inclined surface 110 can be reduced. However, this time, due to the high viscosity, the film thickness of the first photoresist becomes too thick, resulting in another problem that the pattern resolution at the time of photolithography is lowered and microfabrication on the micron order becomes impossible.

  Under these technical backgrounds, the inventor conducted extensive research on forming a metal film on a slope. As a result, if a recess is formed in the step, and a slope is formed by photoresist in this recess, the slope of the slope can be made gentle without using a high-viscosity photoresist. It was conceived that the metal film deposited can be prevented from being broken.

  Accordingly, a first object of the present invention is to provide a method of forming an inclined surface that is more gently inclined than the prior art and connects the upper and lower steps of the step.

  A second object of the present invention is to provide a coating layer having a step structure having an inclined surface that is gentler than the prior art.

  A third object of the present invention is to provide a wiring structure which is formed on the covering layer having the above-described step structure and which suppresses step breakage, and a method for forming the same.

  A fourth object of the present invention is to provide a semiconductor device provided with the above wiring structure.

  In order to solve the above-described problem, the inclined surface forming method of the present invention includes the following first to third steps.

In the first step, a step structure having an upper plane, a lower plane, and a side surface connecting both planes is provided, the depth extending from the side plane to the inside between the upper plane and the lower plane , A ground surface on which two grooves facing each other across the groove and standing from the bottom face , and a groove surrounded by a back end face standing from the bottom and constituting the innermost part of the groove are formed Prepare.

In the second step, the viscous fluid coating layer is formed by coating the viscous fluid along the two opposing surfaces and the back end surface and between the upper and lower planes, including a concave groove on the base. The viscous fluid application layer having a slanted surface whose height decreases as the surface of the viscous fluid application layer in the concave groove moves from the upper flat surface side as the back side of the concave groove toward the lower flat surface side as the opening side of the concave groove. Form a layer.

  In the third step, the viscous fluid coating layer is patterned so as to leave an inclined surface in the groove.

  More preferably, it is preferable to form a plurality of concave grooves on the base and form the viscous fluid application layer so that the surface of the viscous fluid application layer has an inclined surface in each of the plurality of concave grooves.

  In addition, the wiring structure forming method of the present invention utilizes the above-described inclined surface forming method. That is, the first photoresist is used as the viscous fluid.

  In the third step, the first photoresist coating layer is subjected to photolithography patterning, and the island-shaped first photoresist layer is formed in the first region including the inclined surface and straddling the upper and lower planes. A step of forming the remaining layer.

  In the fourth step, after the third step, a second photoresist is applied to the entire exposed surface on the upper side of the structure obtained in the third step to form a second photoresist coating layer. Subsequently, the second photoresist coating layer is patterned by photolithography, so that a part of the upper plane outside the first region, an inclined surface, and a part of the lower plane outside the first region are formed. A portion of the second photoresist coating layer existing in the continuous second region is removed, and a second photoresist pattern is formed in a region outside the second region.

  In the fifth step, a metal film to be a wiring structure is deposited on the entire exposed surface on the upper side of the structure obtained in the fourth step by a vacuum evaporation method.

  In the sixth step, the second photoresist pattern is removed by lift-off together with the metal film existing in the region other than the second region.

  In depositing the metal film, a sputtering film forming method may be used instead of the vacuum evaporation method.

  The coating layer having a step structure according to the present invention includes a base and a viscous fluid coating layer.

The base is provided with a step structure having an upper plane, a lower plane, and a side surface connecting these two planes, and has a depth extending from the side surface to the inside between the upper and lower planes , from the bottom surface and the bottom surface. Two opposing surfaces that are erected and are opposed to each other with the concave groove interposed therebetween, and a concave groove that is erected from the bottom surface and surrounded by a back end face that forms the innermost part of the concave groove are formed.

The viscous fluid application layer includes a groove on the base, is patterned along the two opposing surfaces and the back end surface , and is formed between the upper and lower planes, and the height of the surface in the groove is And an inclined surface that becomes lower from the upper flat surface side as the inner side of the concave groove toward the lower flat surface side as the opening side of the concave groove .

  Here, it is preferable to use a photoresist as the viscous fluid.

  Further, as the viscous fluid, SOG (spin on glass) or resin may be used.

  The wiring structure of the present invention includes the above-described viscous fluid coating layer and a metal film deposited on the inclined surface of the viscous fluid coating layer.

  A semiconductor device according to the present invention includes the above-described wiring structure as a constituent element.

  In the method of forming an inclined surface according to the present invention, the distribution of the viscous fluid on the substrate is (1) the structure of the substrate, (2) its own viscosity (fluidity), (3) the adhesive force to the substrate, and (4) It is determined by four factors of its own weight.

  That is, in the concave groove, the viscous fluid must flow through a narrow groove (concave groove) according to its own weight and viscosity while adhering to the side surface and the bottom surface of the concave groove. That is, the flow of the viscous fluid is restricted in the concave groove. As a result, the viscous fluid is distributed such that the height gradually decreases from the innermost part of the concave groove toward the opening, thereby forming an inclined surface.

  On the other hand, the viscous fluid freely flows from the upper plane to the lower plane on the side surfaces other than the concave grooves because there is no structure that restricts the flow. As a result, the viscous fluid is distributed so as to cover the side surface to form a slope.

  Accordingly, the slope of the inclined surface formed in the concave groove becomes gentler than the slope formed on the side surface by the amount that the flow of the viscous fluid is limited.

  Thus, in the method for forming the inclined surface of the present invention, the inclined surface is formed by appropriately designing the shape of the concave groove provided in the base. That is, it is not necessary to use a viscous fluid having a high viscosity when forming the inclined surface.

  Therefore, when a photoresist is used as the viscous fluid, a sufficiently gentle inclined surface can be formed even with a low viscosity photoresist. Therefore, the film thickness of the photoresist on the base can be reduced to 3 μm or less. As a result, micro-order fine processing can be performed on the photoresist in photolithography.

  Further, according to the method of forming an inclined surface of the present invention, an inclined surface with a gentle inclination can be formed. Therefore, when a metal film is formed on the inclined surface by vacuum vapor deposition or sputtering, the metal film is deposited on the inclined surface without any step regardless of the incident angle of the metal atoms flying to the inclined surface. be able to.

  In addition, since the method for forming a wiring structure according to the present invention uses the above-described method for forming an inclined surface, the wiring structure for connecting the upper and lower planes to the second region is derived from the disconnection. It can be formed without causing disconnection.

  Moreover, according to the coating layer of the step structure of the present invention, it is possible to form an inclined surface having a gentle inclination in the groove.

  Further, according to the semiconductor device of the present invention, disconnection due to disconnection is reduced, so that the reliability of the wiring structure is increased, and as a result, the yield of the semiconductor device is improved.

  Embodiments of the present invention will be described below with reference to the drawings. Each drawing merely schematically shows the shape, size, and arrangement relationship of each component to the extent that the present invention can be understood. Moreover, although the preferable structural example of this invention is demonstrated below, the material, numerical condition, etc. of each component are only a preferable example. Therefore, the present invention is not limited to the following embodiment.

  With reference to FIGS. 1 to 13, an inclined surface and a wiring structure according to the embodiment and a method of forming them will be described. FIG. 1 is a perspective view of the base.

(First step)
First, the structure 10 shown in FIG. 1 is prepared. The structure 10 includes a substrate 11 and a first element 12. Specifically, on the main surface 11 a of the substrate 11, the substantially rectangular parallelepiped first element 12 constituting the semiconductor device is disposed. Although not shown, a second element constituting the semiconductor device is also formed on the main surface 11 a of the substrate 11.

  The first element 12 has a height higher than that of the main surface 11 a, and an upper surface 14 that extends substantially parallel to the main surface 11 a and a side surface 16 that extends substantially perpendicular to the main surface 11 a of the substrate 11. It has.

  In the example shown in FIG. 1, the planar shape of the upper surface 14 of the first element 12 is substantially square. The length of one side of this square is preferably about 10 μm, for example. The height H of the first element 12, that is, the distance between the upper surface 14 and the main surface 11a is preferably about 3 μm, for example.

  A recess 18 is formed in the first element 12. The recess 18 is a rectangular parallelepiped hole with the main surface 11 a of the substrate 11 as the bottom. That is, the recess 18 extends substantially perpendicularly to the side surface 16 from the opening 20 provided in the side surface 16 toward the inside of the first element 12. The recess 18 is formed to a depth extending from the upper surface 14 of the first element 12 to the main surface 11 a of the substrate 11.

  Accordingly, the recess 18 has an opening width (which is also a groove width) from the side surface 16 of the first element 12 to D and a depth (height) corresponding to the thickness H of the first element 12. , And can be regarded as a concave groove 22 formed with a depth (full length) L into the first element 12.

  In the example shown in FIG. 1, the overall length L (full length) of the recess 18 is preferably about 3 μm, for example. The opening width D is preferably about 2 μm, for example. The height H is preferably about 3 μm, for example.

  The concave groove 22 is a space surrounded by the bottom surface 18a, the two opposing surfaces 18b and 18b, and the back end surface 18c.

  The facing surfaces 18b and 18b are flat surfaces that face each other with the concave groove 22 interposed therebetween. The opposing surfaces 18b, 18b extend in parallel to each other. Further, the facing surfaces 18b and 18b extend substantially vertically from the bottom surface 18a.

  The back side end face 18 c is a plane that forms the innermost part of the groove 22. The back side end face 18c extends substantially vertically from the bottom face 18a.

  Hereinafter, the direction perpendicular to the side surface 16 with respect to the recess 18 is referred to as a “longitudinal direction”. A direction parallel to the side surface 16 is referred to as a “short direction”. Furthermore, a direction perpendicular to the main surface 11a is referred to as a “height direction”.

  Here, the base 13 is defined as a structure having a step structure having a main surface 11a as a lower flat surface, an upper surface 14 as an upper flat surface, and a side surface 16, and in which a recess 18 is formed. .

  The base 13 is formed simultaneously with the formation of the structure 10. That is, in the flat substrate 11 before the first element 12 is formed, a region excluding the region where the first element 12 and the recess 18 are to be formed is etched from the main surface 11a side to a predetermined depth. Thereby, the 1st element 12 and the recessed part 18 are formed simultaneously, and the foundation | substrate 13 is obtained as a result.

(Second step)
FIG. 2 is a perspective view schematically showing the underlayer of FIG. 1 in the second step together with the photoresist, and is shown by a cross-section cut along a plane vertically moved along the line II in FIG. FIG. 3 is a diagram showing a cross-sectional cut along with the first photoresist coating layer, which is a base cut by cutting the II line in FIG. 1 vertically. FIG. 4 is a view showing a cross-section cut along with a first photoresist coating layer, which is a base cut by cutting the II-II line of FIG. 1 vertically. In FIG. 2, the surface of the first photoresist coating layer 24 is meshed with a solid line in order to more clearly show the distribution state of the first photoresist coating layer 24 on the base 13.

  Subsequent to the first step, as shown in FIG. 3, a first photoresist as a viscous fluid is applied to the entire surface of the base 13 on the main surface 11a side by, for example, a spin coating method. As a result, the first photoresist is applied to the main surface 11a, the concave groove 22 and the upper surface 14, and the first photoresist coating layer 24 is formed.

  Here, as the first photoresist, a positive photoresist (S1830: manufactured by Shipley Co., Ltd.) having a viscosity of about 30 mPas (millipascal second) was used. Further, the spin coating condition is that the rotational speed is about 5000 rpm, and the holding time at this rotational speed is about 10 seconds. The film thickness of the first photoresist coating layer 24 is about 1.5 μm on the main surface 11a.

  Here, the behavior of the first photoresist will be described with reference to FIGS.

  The first photoresist flows on the base 13 according to its viscosity, adhesive strength with the base 13, and its own weight. As a result, as shown in FIG. 2, the first photoresist coating layer 24 is formed so as to gently cover the side surfaces 16 and the recesses 18.

  Specifically, on the side surface 16 excluding the recesses 18, the first photoresist coating layer 24 is gently distributed so that the height decreases from the upper surface 14 side toward the main surface 11a side. Here, as shown in FIG. 3, a surface formed by the surface of the first photoresist coating layer 24 covering the side surface 16 is represented as a slope 28. Further, the acute angle side of the angle formed between the tangential plane of the slope 28 and the main surface 11a is represented as an inclination angle θ ′.

  Referring to FIG. 2 again, in the concave portion 18, the first photoresist coating layer 24 is gently distributed so that the height decreases from the back end surface 18c side toward the opening 20 side.

  More specifically, the first photoresist flows into the concave portion 18 (the concave groove 22) along the opposing surfaces 18b and 18b and the back end surface 18c. As a result, as shown in FIG. 4, the first photoresist coating layer 24 is distributed in a U-shaped concave shape (U-valley shape) when viewed in a cut surface parallel to the side surface 16.

  Here, as shown in FIG. 3, it is composed of the bottom of the U-shaped valley of the first photoresist coating layer 24 in the concave groove 22, and the height of the surface gradually increases from the upper surface 14 side toward the main surface 11a side. It is assumed that the lower surface is represented as the inclined surface 26. Furthermore, the acute angle side of the angle formed between the inclined surface 26 and the main surface 11a is expressed as an inclination angle θ. Here, the inclination angle θ is an acute angle side angle formed between the tangential plane 26a and the main surface 11a at a point on the inclined surface 26 that gives the maximum inclination to the main surface 11a.

  Next, the reason why the first photoresist coating layer 24 forms the inclined surface 26 in the concave groove 22 will be described.

  The first photoresist has viscosity and adhesive strength with the base 13. For this reason, the first photoresist flowing into the concave groove 22 is deposited with a certain thickness on the opposing surfaces 18b, 18b and the back end surface 18c. On these surfaces 18b, 18b and 18c, due to the balance with gravity (self-weight), the first photoresist is distributed such that (1) the film thickness is thin on the upper side and the film thickness is thick on the lower side.

  Further, the recess 18 is closed at one end (the back end face 18c) and has an opening 20 at the other end. Therefore, the first photoresist on the bottom surface 18a of the concave groove 22 flows in the opening direction (opening 20 side). As a result, (1) the first photoresist has a thick film thickness on the back side (back side end surface 18c side) of the concave groove 22 and a thin film thickness on the opening 20 side.

  Due to the combined effects of (1) and (2), the first photoresist is distributed in the concave groove 22 such that the height decreases from the back end face 18c side to the opening 20 side. That is, the inclined surface 26 is formed by the first photoresist coating layer 24 inside the concave groove 22.

  The inclination angle θ of the inclined surface 26 is not strictly constant because the first photoresist has viscosity, and is gently convex toward the main surface 11a. However, as long as the first photoresist having the above-described viscosity is used, the inclination angle θ of the inclined surface 26 may be regarded as substantially constant.

Here, the inclination angle θ of the inclined surface 26 is given by an angle of about tan ⁻¹ (H / L) since the height changes by about H with respect to the total length L of the concave groove 22. Specifically, since the overall length L of the recess 18 is about 3 μm and the height H is about 3 μm, the inclination angle θ is about 45 °. In addition, although mentioned later in detail, inclination-angle (theta) is smaller than the incident angle (lambda) of the metal atom in vacuum evaporation (6th process).

  On the other hand, on the slope 28, the distance L ′ (the distance measured perpendicularly to the side surface 16 on the main surface 11a) required for the height to change by about H is smaller than L (L ′ <L). Therefore, the inclination angle θ of the inclined surface 26 that requires a long distance L to change the height by about H is smaller than the inclination angle θ ′ of the inclined surface 28 (θ> θ ′).

(Third step)
FIGS. 5A and 5B are a plan view of the structure body in the third step and a cross-sectional cut surface cut along a plane in which the above-mentioned II line is vertically moved up and down, respectively.

  Next, a structure 30 as shown in FIGS. 5A and 5B is formed. That is, photolithography is performed on the first photoresist coating layer 24. Thus, the island-shaped first photoresist coating layer 24d (hereinafter also referred to as island-shaped coating layer 24d) is patterned in the first region 32.

  Here, the first region is a substantially rectangular region in plan view that includes the inclined surface 26 (concave groove 22) and extends across the upper surface 14 and the main surface 11a.

  In this illustrated example, the island-shaped coating layer 24d is patterned so that the center line (C1) of the first region 32 and the center line C1 of the recess 18 coincide. Here, the center line (C1) of the first region 32 indicates a straight line connecting the midpoints of the two sides 32a and 32a of the first region 32 extending in parallel with the side surface 16. The center line of the recess 18 indicates a straight line C1 connecting the midpoint of the opening 20 in the short direction and the midpoint of the back end surface 18c in the short direction.

  Since a positive photoresist is used as the first photoresist, the island-shaped coating layer 24d is patterned into a trapezoidal cross section by photolithography. That is, in the island-shaped coating layer 24d, the lower surface 24b has a larger area than the upper surface 24a. That is, the outer peripheral side surface 24c of the island-shaped coating layer 24d is formed so as to be gradually widened toward the main surface 11a side (FIGS. 5A and 5B).

(4th process)
FIG. 6 is a view showing a cross-sectional cut surface obtained by cutting the structure in the fourth step along a plane in which the above-described II line is vertically moved up and down.

  Next, a structure 40 as shown in FIG. 6 is formed. That is, the wiring support 25 is formed by performing post-exposure baking (hereinafter also referred to as PEB) for about 20 minutes at a temperature of about 150 ° C. on the structure 30 (FIG. 5B).

  When PEB is performed under these conditions, the island-shaped coating layer 24d generally undergoes thermal deformation, and the upper end corner (corner portion) of the outer peripheral side surface 24c is removed and rounded. The island-shaped coating layer 24 that has undergone this thermal deformation is referred to as a wiring support 25.

  Due to the thermal deformation caused by PEB, the inclination of the outer peripheral side surface 24 c with respect to the upper surface 14 is further reduced at the boundary between the wiring support 25 and the upper surface 14. As a result, the wiring support 25 and the upper surface 14 are smoothly connected. The same applies to the boundary between the wiring support 25 and the main surface 11a, and both 25 and 11a are smoothly connected.

  The first to fourth steps correspond to the inclined surface forming method of the present invention. Moreover, the wiring support body 25 having the inclined surface 26 formed by the first to fourth steps corresponds to the coating layer of the step structure of the present invention.

(5th process)
FIGS. 7A and 7B are a plan view of the structure body in the fifth step and a cross-sectional cut surface cut along a plane in which the above-mentioned II line is vertically moved up and down, respectively.

  Next, a structure 50 as shown in FIGS. 7A and 7B is formed. That is, the second photoresist is applied to the entire surface of the structure 40 (FIG. 6) including the first region 32 on the main surface 11a side. Here, the second photoresist coated on the entire main surface 11a side is referred to as a second photoresist coating layer (not shown).

  Then, a part of the upper surface 14 outside the first region 32 (end region 36a), the inclined surface 26, and a part of the main surface 11a outside the first region 32 (end region 36b) are continuous. The second photoresist existing in the second region 36 is removed.

  That is, the second photoresist pattern 34 is formed by performing patterning by photolithography on the second photoresist coating layer.

  Here, a negative photoresist (LMR-F33: manufactured by Fuji Pharmaceutical Co., Ltd.) was used as the second photoresist. Then, the second photoresist was applied to the entire surface of the structure 40 on the main surface 11a side by spin coating. The film thickness of the second photoresist coating layer is about 1 μm on the main surface 11a.

  The second region 36 is a substantially rectangular region including the recess 18 in plan view. The length of the side 36 c in the direction perpendicular to the side surface 16 of the second region 36 is larger than the length of the corresponding side 25 c of the wiring support 25. Further, the length of the side 36 d in the direction parallel to the side surface 16 of the second region 36 is smaller than the length of the corresponding side 25 d of the wiring support 25. Further, the wiring support 25, the second region 36, and the center line C1 of the recess 18 are common in plan view.

  Therefore, the upper surface 14 of the first element 12 is exposed in a part of the upper surface 14 outside the first region 32, that is, in the end region 36 a on the upper surface 14 side of the second region 36. That is, the upper surface 14 is exposed in the end region 36a between the edge on the upper surface 14 side of the wiring support 25 and the side wall of the second photoresist pattern 34 facing the edge. The end region 36a is a region where the wiring connection terminals (electrode pads and the like) of the first element 12 are provided.

  Similarly, the main surface 11a of the substrate 11 is exposed in a part of the main surface 11a outside the first region 32, that is, in the end region 36b on the main surface 11a side of the second region 36. That is, the main surface 11a is exposed in the end region 36b from the edge of the wiring support 25 on the main surface 11a side to the side wall of the second photoresist pattern 34 facing the end edge. The end region 36b is a region where the wiring connection terminals (electrode pads and the like) of the second element are provided.

  Further, as described above, the length of the side 36 d of the second region 36 is smaller than the length of the side 25 d of the wiring support 25. Therefore, the region in the vicinity of the two sides 25 c and 25 c of the wiring support 25 is covered with the second photoresist pattern 34.

  The center line C1 of the second region 36 indicates a straight line connecting the midpoints of the two sides 36d and 36d in the direction parallel to the side surface 16. Further, the center line C1 of the wiring support 25 matches the center line C1 of the first region 32 described above.

(6th process)
FIG. 8 is a diagram showing a cross-sectional cut surface obtained by cutting the structure in the sixth step along a plane in which the above-described II line is vertically moved up and down. FIGS. 9A to 9C are process diagrams for explaining a deposition process of a metal film deposited on an inclined surface in vacuum vapor deposition, and cut along a plane in which the above-described II line is vertically moved up and down. It is shown by the cut section.

  Next, a structure 60 as shown in FIG. 8 is formed. That is, the metal film 42 to be the wiring structure 38 is deposited in the region on the main surface 11 a side of the structure 50 including the second region 36.

  Specifically, the metal film 42 is deposited on the entire surface of the structure 50 on the main surface 11a side by vacuum evaporation. In depositing the metal film 42, the vacuum evaporation apparatus 119 (FIG. 15A) described in the section (Problems to be solved by the invention) is used.

  Here, the metal film 42 was a laminated film in which a Ti film having a thickness of about 50 nm and an Au film having a thickness of about 300 nm were deposited in this order. Further, the film thickness (about 350 nm) of the metal film 42 is a value in a plane parallel to the main surface 11a.

  Thereby, the metal film 42 a is deposited on the entire surface of the second region 36. Similarly, a metal film 42 b is deposited on the second photoresist pattern 34 outside the second region 36.

  Here, the deposition process of the metal film 42a on the inclined surface 26 will be described with reference to FIGS.

  FIGS. 9A to 9C are process diagrams showing the deposition process of the metal film 42a, respectively, and are shown by a cross-section cut out of only the inclined surface 26 of the structure 50 (FIG. 7).

  9A to 9C, the metal atoms deposited on the inclined surface 26 come from the incident directions A, B, and C in the same manner as described with reference to FIG. 15B. Therefore, the incident angles of the metal atoms are λ and λ ′.

(Step A: (FIG. 9A))
First, consider a case where metal atoms fly from the incident direction A (arrow in the figure) to the inclined surface 26.

In this case, the inclination angle θ of the inclined surface 26 is smaller than the incident angle λ of the metal atoms flying to the inclined surface 26 (λ> θ). Therefore, metal atoms also fly to the inclined surface 26. As a result, the metal film 42 a ₁ is deposited on the entire surface of the second region 36.

However, since metal atoms are incident on the inclined surface 26 at a lying angle, the number of metal atoms incident per unit area of the inclined surface 26 is reduced. As a result, the thickness of the metal film 42a ₁ on the inclined surface 26 is made thinner than the other regions.

(Step B: (FIG. 9B))
After stage A, the structure 50 rotates by a predetermined angle with respect to the evaporation source 116. Thereby, a metal atom flies to the inclined surface 26 from the incident direction B (arrow in the figure). As a result, the metal film 42 a ₂ is deposited on the entire surface of the second region 36.

(Stage C: (FIG. 9C))
After stage B, the structure 50 rotates by a predetermined angle with respect to the evaporation source 116. Thereby, a metal atom flies to the inclined surface 26 from the incident direction C (arrow in the figure). Thereby, the metal film 42 a ₃ is deposited on the entire surface of the second region 36.

  After the stage C, the metal film 42 is deposited by repeating the above-described stages A to C.

  Thus, since the inclination angle θ of the inclined surface 26 is smaller than the incident angle λ, metal atoms are constantly deposited on the inclined surface 26 regardless of the incident direction of the metal atoms. As a result, unlike the metal film 120 (FIGS. 16A to 16D) described in the section (Problems to be solved by the invention), the metal film 42 does not break.

(Seventh step)
FIG. 10 is a view showing a cross-sectional cut surface obtained by cutting the wiring structure obtained after the seventh step along a plane in which the above-described II line is vertically moved up and down.

  Finally, a structure 70 as shown in FIG. 10 is completed. That is, the second photoresist pattern 34 is removed together with the unnecessary metal film 42b by lift-off. Specifically, the second photoresist pattern 34 is dissolved by immersing the structure 60 in a resist stripping solution.

  Thereby, the wiring structure 38 that electrically connects the first element 12 existing on the upper surface 14 and the second element existing on the main surface 11a is formed.

  Note that a semiconductor device is formed by performing a predetermined process (passivation film formation or the like) after the seventh process.

  In the following, the effects produced by this embodiment will be described.

  According to the method of forming the inclined surface 26 of this embodiment, the upper surface 14 of the base 13 is connected to the main surface 11a, and the inclination is gentler than that of the conventional inclined surface 110 (FIG. 14) and inclined surface 28 (FIG. 3). An inclined surface 26 can be obtained. Further, if the inclination angle θ of the inclined surface 26 is made smaller than the incident angle λ of the metal atoms at the time of vacuum deposition, metal atoms can be continuously deposited on the inclined surface 26 regardless of the change of the incident angle λ. Therefore, disconnection of the metal film 42 can be suppressed.

  Further, the recess 18 in which the inclined surface 26 is formed is formed simultaneously with the structure 10. That is, it is not necessary to add a new process for forming the recess 18.

  Further, the inclination angle θ of the inclined surface 26 is made smaller than the incident angle λ of the metal atoms only by adjusting the dimensions (height H, total length L, and width D) of the recess 18. That is, it is not necessary to increase the viscosity of the first photoresist in order to obtain the gently inclined surface 26.

  Therefore, a low viscosity thing can be used as a 1st photoresist, As a result, the film thickness of the 1st photoresist application layer 24 on the main surface 11a can be suppressed to 3 micrometers or less (about 1.5 micrometers). Thereby, in the photolithography process, microfabrication on the order of microns can be performed on the first photoresist coating layer 24.

  In addition, since the covering layer of the step structure of this embodiment forms the inclined surface 26 by the wiring support 25, it has a gentler inclination than the inclined surface 110 (prior art) and the inclined surface 28 (FIG. 3). The upper surface 14 and the main surface 11a can be connected.

  Further, according to the method of forming the wiring structure 38 of this embodiment, the inclination angle θ of the inclined surface 26 on which the metal film 42a to be the wiring structure 38 is deposited is set to the incident angle of the metal atoms during the vacuum evaporation. It is smaller than λ. As a result, the metal atoms are continuously deposited on the inclined surface 26 regardless of the change in the incident angle λ of the metal atoms, so that the disconnection of the metal film 42 can be suppressed. Accordingly, it is possible to improve the reliability of the wiring structure 38 wired across the step structure of the base 13. Therefore, it is possible to suppress the occurrence of disconnection of the wiring structure 38, which has been regarded as a problem in the related art, and to improve the manufacturing yield of semiconductor devices using the wiring structure 38.

  Here, specific numerical values regarding the improvement of the manufacturing yield are given. According to the inventor's evaluation, the manufacturing yield of the semiconductor device provided with the wiring structure 38 of this embodiment is higher than that of the semiconductor device in which the wiring is formed on the slope 110 (FIG. 14) according to the conventional method (background art). Improved by about 30%.

  Hereinafter, allowable condition changes and modifications in this embodiment will be exemplified to clarify the technical scope of the present invention.

  FIGS. 11A and 11B are views showing a modification of the concave portion of this embodiment. FIGS. 12A and 12B are views showing a modification of the concave portion of this embodiment. FIGS. 13A and 13B are views showing a modification of the concave portion of this embodiment.

  The upper surface 14 and the main surface 11a constituting the base 13 do not necessarily have to be parallel. If the upper surface 14 and the main surface 11a are connected by the side surface 16 whose height changes discontinuously, the upper surface 14 and the main surface 11a may be arranged non-parallel.

  Further, the side surface 16 constituting the base 13 does not necessarily need to extend perpendicular to the main surface 11a. Also, the side surface 16 need not be a flat surface. The side surface 16 only needs to have a region having an inclination angle larger than the incident angle λ of the metal atom described above. For example, the side surface 16 may be convexly curved in the direction of the main surface 11a. It may be concavely curved in the 11a direction.

  Moreover, the connection part of the side surface 16 and the upper surface 14 does not need to have edge shape, ie, a clear ridgeline. The corner of the connecting portion between the side surface 16 and the upper surface 14 may be rounded.

  Further, the height of the side surface 16 (the height of the step) need not be 3 μm. According to the inventor's evaluation, if the height of the side surface 16 is in the range of 1 to 10 μm, the shape of the recess 18 (full length L and width D) and the viscosity of the first photoresist are optimized to moderately. It is possible to form the inclined surface 26 having an appropriate inclination.

  That is, the inclination angle θ of the inclined surface 26 formed in the recess 18 is a function of the shape of the recess 18 (height H, total length L, and width D) and the viscosity of the first photoresist. Therefore, when the height of the side surface 16 is high, the first photoresist having a higher viscosity than (Countermeasure 1) is used, (Countermeasure 2) The overall length L of the recess 18 is increased, and (Countermeasure 3) One or more of the three measures of reducing the width D may be implemented.

  However, (Countermeasure 1) may increase the thickness of the first photoresist coating layer 24 and reduce the pattern resolution in photolithography. Therefore, it is preferable to first implement (Countermeasure 2) and (Countermeasure 3) in an appropriate combination and implement (Countermeasure 1) when satisfactory results are still not obtained.

  The first photoresist preferably has a viscosity such that the film thickness on the main surface 11a of the first photoresist coating layer 24 is 3 μm or less. By setting the first photoresist to such a viscosity, the pattern resolution in photolithography can be maintained on the order of microns. Further, by adjusting the shape (full length L and width D) of the recess 18 by setting the first photoresist to such a viscosity, a gently inclined surface 26 is formed with respect to a step having a height of about 10 μm at the maximum. Can be formed.

  In addition, the inclination angle θ of the inclined surface 26 is preferably smaller than the inclination angle θ ′ of the inclined surface 28 formed on the side surface 16. More preferably, the inclination angle θ is preferably smaller than the incident angle λ of metal atoms during vacuum deposition. From the viewpoint of suppressing disconnection of the metal film 42, the inclination angle θ is preferably a smaller value in a range satisfying θ <λ. In the case of general vacuum deposition, the incident angle λ of the metal atoms is about 50 ° to 90 °, and therefore the inclination angle θ is preferably at least smaller than the incident angle.

  Further, the concave groove 22 of the concave portion 18 formed in the base 13 does not need to extend perpendicular to the side surface 16. That is, the concave groove 22 may be inclined and extended with respect to the side surface 16.

  Further, the number of the recesses 18 formed in the base 13 is not limited to one. For example, as shown in FIG. 11A, a plurality of recesses 18 ′ and 18 ′ may be formed in the base 13.

  Further, the planar shape of the recess 18 is not limited to a rectangular shape. For example, as shown in FIG. 11B, the back side end face 18c 'may be rounded in an arc shape.

  Further, the opposing surfaces 18b, 18b and the back end surface 18c of the recess 18 do not need to extend perpendicularly to the main surface 11a. As shown in FIG. 12A, the groove 22 may have an inclination that the width of the concave groove 22 decreases according to the depth from the upper surface 14. Similarly, as shown in FIG. 12 (B), the groove 22 may have an inclination such that the width of the concave groove 22 increases according to the depth from the main surface 11a.

  As shown in FIG. 13A, the bottom surface 18a of the recess 18 does not have to be continuous with the main surface 11a without a step. The bottom surface 18a may be higher than the main surface 11a. By doing in this way, even if the height of the side surface 16 (the height of the step) is 10 μm or more, the upper surface 14 and the main surface 11a can be gently connected by the inclined surface 26.

  Further, as shown in FIG. 13B, the bottom surface 18a of the recess 18 does not need to be parallel to the main surface 11a. The bottom surface 18 a may be formed in a slope shape that increases in height according to the distance from the opening 20. By doing in this way, even if the height of the side surface 16 (the height of the step) is 10 μm or more, the upper surface 14 and the main surface 11a can be gently connected by the inclined surface 26.

  In this embodiment, in the third step, the width of the island-shaped coating layer 24d in the short direction (the length of the side 32a: FIG. 5A) is made larger than the groove width D of the concave groove 22. ing. However, the width in the short direction of the island-shaped coating layer 24d is not limited to this. For example, the width of the island-shaped coating layer 24d in the short direction may be narrower than the groove width D, and the first photoresist layer 24d may be formed to remain within the groove width. That is, the width in the short direction of the island-shaped coating layer 24 d only needs to be larger than the design width of the wiring structure 38 formed on the inclined surface 26.

  Further, at the same time as or after the seventh step, the wiring support 25 may be removed by a known method. By doing so, an air bridge wiring made of the metal film 42a is formed. By forming the air bridge wiring, the parasitic capacitance to the wiring can be reduced.

  The viscous fluid is not limited to the first photoresist, and an inorganic SOG film or a resin such as polyimide may be used. By using the SOG film, heat resistance of 300 to 1000 ° C. can be imparted to the inclined surface 26. In addition, by using a resin whose viscosity is adjusted, a thick coating layer can be formed on the base 13. As a result, a gentle inclined surface can be formed even when the height of the step is large.

  Further, the fourth step may be omitted if the island-shaped coating layer 24d is formed to be strong enough to withstand the processing after the fifth step.

  In this embodiment, the metal film 42 is deposited by a vacuum vapor deposition method. However, the metal film may be deposited by a sputtering film formation method. Thereby, it is possible to prevent the occurrence of step breaks even in the metal film deposited by the sputtering film forming method.

  Further, the method of forming the inclined surface 26 of the present invention can be applied to the manufacture of devices that require a gentle slope, in addition to being used for forming the wiring structure 38.

It is a perspective view of a foundation | substrate. It is a perspective view which shows the foundation | substrate of FIG. 1 in a 2nd process with a photoresist, and has shown the area | region along the II line | wire of FIG. It is a figure which shows the cross-sectional cut which drawn the foundation | substrate cut | disconnected by the line along the II line | wire of FIG. 1 with the 1st photoresist. It is a figure which shows the cross-section cut which drew the foundation | substrate cut | disconnected by the line along the II-II line | wire of FIG. 1 with the 1st photoresist. (A) And (B) is a figure which shows the cross-sectional cut | disconnection cut | disconnected by the surface where the above-mentioned II line was vertically raised and lowered, respectively, and the top view of the structure in a 3rd process. It is a figure which shows the cross-section cut | disconnection which cut | disconnected the structure in a 4th process in the surface which raised / lowered the above-mentioned II line | wire vertically. (A) And (B) is a figure which shows the cross section cut | disconnected by the surface where the above-mentioned II line | wire was vertically moved up and down, and the top view of the structure in a 5th process, respectively. It is a figure which shows the cross section cut | disconnected which cut | disconnected the structure in a 6th process by the surface which made the above-mentioned II line | wire vertically moved up and down. (A)-(C) are process drawings for explaining the deposition process of a metal film deposited on an inclined surface in vacuum evaporation, and is a cross-section cut along a plane in which the above-mentioned II line is vertically moved up and down. It is shown with a cut end. It is a figure which shows the cross section cut | disconnected which cut | disconnected the wiring structure obtained after a 7th process in the surface which raised / lowered the above-mentioned II line | wire vertically. (A) And (B) is a figure which shows the modification of the recessed part of this embodiment. (A) And (B) is a figure which shows the modification of the recessed part of this embodiment. (A) And (B) is a figure which shows the modification of the recessed part of this embodiment. (A) And (B) is process drawing with which it uses for description of a prior art. (A) And (B) is a figure with which it uses for description of the mechanism of step breakage generation | occurrence | production in a prior art. (A)-(E) are process drawings with which it uses for description of the mechanism of step breakage generation | occurrence | production in a metal film in a prior art.

Explanation of symbols

10, 30, 40, 50, 60, 70 Structure 11 Substrate 11a Main surface 12 First element 13 Base 14 Upper surface 16 Side surface 18, 18 'Recess 18a Bottom surface 18b Opposing surface 18c, 18c' Back side end surface 20 Opening 22 Concave groove 24 First photoresist coating layer 24a Upper surface 24b Lower surface 24c Outer peripheral side surface 24d Island-shaped first photoresist coating layer (island-shaped coating layer)
25 wiring support 25c, 25d, 32a, 36c, 36d side 26 inclined surface 26a tangential plane 28 slope 32 first region 34 second photoresist pattern 36 second region 36a, 36b end region 38 wiring structure 42, 42a, _{42a 1, 42a 2, 42a 3} , 42b metallic film

Claims (9)

An upper plane, a lower plane,
A step structure having side surfaces connecting these two planes,
The depth from the side surface to the inside is between the upper plane and the lower plane, the bottom surface , two opposing surfaces that are erected from the bottom surface and face each other across the groove, and are erected from the bottom surface. a first step of preparing a base in which the groove is surrounded by the rear end surface which constitutes the deepest portion of the concave groove is formed,
In the viscous fluid application layer, the viscous fluid is applied to the base, including the concave groove, along the two opposing surfaces and the back end surface, and between the upper plane and the lower plane. The height of the surface of the viscous fluid coating layer in the concave groove decreases from the upper flat surface side as the back side of the concave groove toward the lower flat surface side as the opening side of the concave groove. A second step of forming the viscous fluid coating layer having an inclined surface;
And a third step of patterning the viscous fluid coating layer so as to leave the inclined surface in the concave groove. In the second step, a slope is formed by the surface of the viscous fluid coating layer extending to a region other than the concave groove across the upper plane and the lower plane,
The inclination angle measured with respect to the lower step plane of the inclined surface formed in the concave groove is smaller than an inclination angle measured with respect to the lower step plane of the inclined surface. A method of forming an inclined surface. A method of forming a wiring structure using the method of forming an inclined surface according to claim 1 or 2,
A first photoresist is used as the viscous fluid,
In the third step, the first photoresist coating layer is patterned by photolithography, and includes an island-shaped first in a first region including the inclined surface and straddling the upper and lower planes. Including a step of forming a remaining photoresist layer,
After the third step, a second photoresist is applied to the entire exposed surface on the upper side of the structure obtained in the third step to form a second photoresist coating layer,
The second photoresist coating layer is patterned by photolithography, and a part of the upper flat surface outside the first region, the inclined surface, and one of the lower flat surfaces outside the first region. A fourth step of removing a portion of the second photoresist coating layer existing in a second region where the portion is continuous, and forming a second photoresist pattern in a region outside the second region;
A fifth step of depositing a metal film to be a wiring structure on the entire exposed surface on the upper side of the structure obtained in the fourth step by a vacuum evaporation method;
And a sixth step of removing the second photoresist pattern together with the metal film existing in a region other than the second region by lift-off.   4. The method for forming a wiring structure according to claim 3, wherein, in the fifth step, the metal film is deposited by a sputtering film forming method instead of the vacuum vapor deposition method. A step structure having an upper plane, a lower plane, and a side surface connecting the two planes, the depth extending from the side plane to the inside between the upper plane and the lower plane ; two opposing surfaces facing each other across the groove erected from, and is formed back end the groove surrounded by the surface constituting the innermost part of upright and said groove from the bottom surface And the base
On the base, the height of the surface in the concave groove is included so as to include the concave groove and to be patterned along the two opposing surfaces and the back end surface and between the upper and lower planes. Is provided with a viscous fluid coating layer having an inclined surface that becomes lower from the upper flat surface side as the back side of the concave groove toward the lower flat surface side as the opening side of the concave groove. Stepped structure covering layer.   The step-structured coating layer according to claim 5, wherein the viscous fluid is a photoresist.   The stepped structure coating layer according to claim 5, wherein the viscous fluid is SOG or resin. Claim 5
A step structure having an upper plane, a lower plane, and a side surface connecting the two planes, the depth extending from the side plane to the inside between the upper plane and the lower plane ; two opposing surfaces facing each other across the groove erected from, and is formed back end the groove surrounded by the surface constituting the innermost part of upright and said groove from the bottom surface And the base
On the base, the height of the surface in the concave groove is included so as to include the concave groove and to be patterned along the two opposing surfaces and the back end surface and between the upper and lower planes. Is provided with a viscous fluid application layer having an inclined surface that becomes lower from the upper flat surface side as the back side of the concave groove toward the lower flat surface side as the opening side of the concave groove,
A wiring structure including a metal film deposited on an inclined surface of the viscous fluid application layer.   A semiconductor device comprising the wiring structure according to claim 8 as a constituent element.

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