JP6102578B2 - Anisotropic plating method - Google Patents

Description

  The present invention relates to an anisotropic plating method, and more particularly to an anisotropic plating method suitable for forming a line and space pattern having a high aspect ratio and a narrow pitch. The present invention also relates to a thin film coil manufactured using such an anisotropic plating method.

  As one method for forming a thin film coil, a so-called anisotropic plating method is known (see Patent Documents 1 and 2). In a general anisotropic plating method, as shown in FIG. 23, first, a thin base metal film 11 is formed on the surface of the substrate 10 (FIG. 23A). Next, a pre-plating frame 12 made of a resist pattern is formed by photolithography and dry etching (FIG. 23B). Next, electrolytic plating (pre-plating) is performed, and the base metal film 11 exposed in the opening of the frame 12 is grown by plating (FIG. 23C). Next, the frame 12 is removed (FIG. 23D), and the excess base metal film 11 is removed by wet etching to reveal the pre-plating pattern 13 (FIG. 23D). Thereafter, electrolytic plating is further performed, and the pre-plating pattern 13 is grown in the vertical direction without a frame. Thereby, a spiral pattern with a high aspect ratio can be formed.

Japanese Patent No. 4046827 Japanese Patent No. 4260913

  However, the above-described conventional anisotropic plating method cannot reliably and accurately control the plating surface state, anisotropic growth, and pattern interval. For this reason, the production yield is poor, and there is a problem that the pattern is deformed due to so-called plating burn and the adjacent lines are short-circuited.

  Conventionally, the anisotropic plating growth mechanism has been considered that plating grows anisotropically due to current concentration above the conductor pattern. However, it is unclear why the current concentrates above the conductor pattern, and the true mechanism was not clear. There is also a theory that lateral plating growth is suppressed by the plating solution not entering the space between adjacent line patterns. However, this principle cannot explain the reason why the space starts to be formed, and further, there are cases where the plating does not grow correctly even in the same space width, and the reason why such a difference occurs is not clear. Actually, the plating pattern is completely immersed in the plating solution, and the plating solution must be present in the space, and the reason why the plating solution does not enter the space is unknown. Therefore, it is required to clarify the true anisotropic plating growth mechanism and to control the anisotropic plating growth more accurately.

  The present invention has been made to solve the above-mentioned problems, and the object of the present invention is to control the plating surface state, anisotropic growth, and pattern spacing with certainty and high accuracy, It is to improve the manufacturing yield. Another object of the present invention is to provide a small and high performance thin film coil manufactured by using such an anisotropic plating method.

  As a result of intensive research on the mechanism of anisotropic plating growth, the inventor of the present application results in plating with a high aspect ratio due to the formation of a thin layer of metal ions accompanying high current application and partial destruction of the thin layer of metal ions by stirring the plating solution. It was found that a pattern can be formed, and a desired high aspect pattern can be reliably formed by controlling the applied current and the stirring speed.

  The present invention is based on such technical knowledge, and the anisotropic plating method according to the present invention is a method for forming a coating film by applying an electric current. Of the metal ion dilute layer of the plating solution formed on the surface of the film formed on the surface of the film, the metal ion dilute layer present in the direction in which selective plating growth is desired is partially made by stirring the plating solution. The film is formed while being destroyed.

  In the present invention, it is preferable that the cross-sectional shape in the formation direction of the film is an arc shape, and plating growth is performed while maintaining the arc shape. According to this, the thin metal ion layer existing in the direction in which plating growth is desired can be easily destroyed by stirring the plating solution, and a high aspect plating pattern can be reliably formed.

  In the present invention, the planar shape of the coating is preferably a line and space pattern. According to this, it is possible to destroy the metal ion diluted layer generated on the upper part while leaving the metal ion diluted layer in the space between the adjacent lines, and thereby, a line with a high aspect and a very narrow pitch. An and space pattern can be formed.

In this invention, it is preferable that the current density at the time of the said film formation is 30-70 A / 100cm < ² >. If the current density is within this range, a thin layer of metal ions having a certain thickness can be generated on the surface of the coating, thereby making it possible to reliably control anisotropic plating growth.

  In the present invention, the plating solution preferably contains a copper ion and a disulfide compound.

  The anisotropic plating method according to the present invention comprises at least one parameter selected from the current density of the current, the composition of the plating solution, the stirring speed of the plating solution, and the distance from the coating to the stirring position of the plating solution. It is preferable to control the space width of the line-and-space pattern. This makes it possible to control anisotropic plating growth with high accuracy.

  Moreover, in order to solve the said subject, the thin film coil by this invention has the spiral pattern formed by the said anisotropic plating method by this invention, It is characterized by the above-mentioned. According to this, a spiral pattern having a high aspect and a very narrow pitch can be formed with high accuracy. Therefore, it is possible to provide a high performance thin film coil having a low direct current resistance and a high inductance.

Furthermore, the anisotropic plating method according to the present invention includes a pre-plating pattern including a first line and space pattern having a first line width, a first space width, and a first thickness on a main surface of a substrate. In the state where there is no frame for individually applying the first current to the pre-plating pattern in a state where the substrate is immersed in a plating solution and forcing the anisotropic growth of each line pattern individually, there is no pre-plating A pattern isotropically grown by plating to form a second line width that is wider than the first line width, a second space width that is narrower than the first space width, and a thickness that is thicker than the first thickness. It has a thickness of 2, forming a first plating pattern including a second line and space pattern having a curved surface at the top of each line pattern, in a state in which immersed the substrate in the plating solution In addition, a second current larger than the first current is passed through the first plating pattern to generate a thin metal ion layer on the surface of the first plating pattern, and the plating solution is stirred to By partially destroying the dilute metal ion layer on the upper part, the first plating pattern is grown anisotropically in a state where there is no frame forcing anisotropic growth of each line pattern individually, second line width, the including the second space width, and the second has a thicker third thickness than the thickness, the third line and space pattern having a curved surface at the top of each line pattern And a step of forming two plating patterns.

In the present invention, the plating solution is preferably a copper sulfate plating solution containing copper ions and a brightener. In addition, the current density of the first current is preferably 3 to 20 A / 100 cm ² , and the current density of the second current is preferably 30 to 70 A / 100 cm ² . This makes it possible to control anisotropic plating growth with high accuracy.

  In the anisotropic plating method according to the present invention, the plating solution stirring member is disposed above the main surface of the substrate, and the stirring member is repeatedly moved forward and backward in a direction parallel to the substrate to dispose the plating solution. It is preferable to stir, thereby partially destroying the thin layer of metal ions at the top of each line pattern. In this case, the stirring member may be a paddle made of a rod-shaped body having a triangular cross section, or may be a stirring lattice made of a plate-like member having a lattice structure. According to this, the partial destruction of the thin metal ion layer can be controlled with high accuracy, and the anisotropic plating growth can be reliably controlled.

  In the anisotropic plating method according to the present invention, the substrate itself is repeatedly moved back and forth in a direction parallel to the substrate to stir the plating solution, whereby the metal ion diluted layer at the top of each line pattern is partially It is also preferred to destroy. According to this method, partial destruction of the diluted metal ion layer can be controlled with high accuracy without using a stirring member, and anisotropic plating growth can be reliably controlled.

  In the present invention, it is preferable that the first to third line and space patterns are spiral patterns. According to this, a spiral pattern having a very narrow pitch with a high aspect can be formed. Therefore, it is possible to provide a thin film coil having a low DC resistance and a high inductance.

Anisotropic plating method according to the present invention, the before forming the first plating pattern, further comprising the step of forming an outer frame surrounding at least an outer side of the first line and space pattern, the outer frame, the second 1 is a line-and-space pattern with a resist pattern formed in said main surface of said substrate so as not to contact the external frame has a vertical side surface to the main surface of the substrate, the side of the first line It is preferable that the third space width be separated from the side surface of the outermost line pattern of the AND space pattern . In this case, it is preferable that the third space width is wider than the second space width. According to this, it is possible to prevent the outermost line pattern from being thickened, and it is possible to form a line-and-space pattern having uniform line widths.

Furthermore, the thin film coil according to the present invention includes a substrate and a plating pattern formed on the substrate, and the plating pattern is formed on the substrate, and has a first line width, a first space width, A pre-plated layer comprising a first spiral pattern having a first thickness, a second line width wider than the first line width, a second space width narrower than the first space width, and It has a second thickness that is thicker than the first thickness, has a curved surface at the top of each line pattern, and consists of a second spiral pattern that covers the top and side surfaces of the first spiral pattern of the pre-plated layer. A first non-frame plating layer; a third thickness greater than the second thickness; a curved surface at the top of each line pattern; and the second spiral of the first non-frame plating layer. Characterized in that it comprises a second non-frame plating layer and a third spiral pattern covering a turn. According to the present invention, a spiral pattern having a high aspect ratio and a very narrow pitch can be formed, thereby realizing a thin film coil having a low DC resistance and a high inductance.

  According to the present invention, the surface state, anisotropic growth, and pattern spacing of plating can be controlled reliably and with high accuracy, and a line and space pattern having a high aspect ratio and a very narrow pitch can be formed. An anisotropic plating method can be provided. Moreover, according to this invention, the small and highly efficient thin film coil manufactured using such an anisotropic plating method can be provided.

It is a schematic diagram for demonstrating the anisotropic plating method by the 1st Embodiment of this invention. 4 is a plan view showing a more specific pattern shape of a pre-plating pattern 13. FIG. It is a schematic diagram for demonstrating the metal ion diluted layer 17. FIG. It is a schematic sectional drawing which shows the detailed structure of a plating pattern. It is a schematic diagram which shows the 1st example of a structure of a plating apparatus. It is a schematic diagram which shows the 2nd example of a structure of a plating apparatus. It is a schematic diagram which shows the 3rd example of a structure of a plating apparatus. It is a schematic perspective view which shows the structure of the stirring grating | lattice in FIG. It is a schematic diagram which shows the 4th example of a structure of a plating apparatus. It is a graph which shows the relationship between an electric current density and stirring speed. It is an optical microscope photograph which shows the surface state of plating. It is a schematic diagram for demonstrating the anisotropic plating method by the 2nd Embodiment of this invention. It is a top view which shows the more specific pattern of the external frame 16, and respond | corresponds to the spiral pre-plating pattern 13 shown in FIG. It is a schematic diagram which shows the thumbnail of the optical micrograph of each sample of the spiral plating pattern on a wafer, and the thickness of a pattern, respectively. It is a detailed SEM image photograph of a spiral plating pattern. It is a schematic diagram which shows the thumbnail of the micrograph of each sample of the spiral plating pattern on a wafer, and the thickness of a pattern, respectively. It is a detailed SEM image photograph of a spiral plating pattern. It is a graph which shows the relationship between a current density and the space width of a plating pattern. It is a graph which shows the relationship between stirring speed and space width. It is a graph which shows the relationship between the brightener (SPS) density | concentration in plating solution, and space width. It is a graph which shows the relationship between the copper sulfate density | concentration in plating solution, and space width. It is a graph which shows the relationship between plating time and the aspect ratio of a plating pattern. It is a schematic diagram which shows the general anisotropic plating method.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic view for explaining an anisotropic plating method according to the first embodiment of the present invention.

In the anisotropic plating method according to the present embodiment, first, a pre-plating pattern 13 is formed on the surface of the substrate 10 as shown in FIG. The pre-plating pattern 13 is a base metal film of a coating to be plated, and can be formed by, for example, the method shown in FIGS. The planar shape of the pre-plating pattern 13 at this time is a line and space pattern, and has a predetermined line width W _L1 and space width W _S1 . The line width W _{L1 at} this time is set to be narrower than the line width W _L2 of the line and space pattern to be finally obtained, and conversely, the space width W _S1 is the line and space pattern to be finally obtained. It is set to be wider than the space width W _S2 space pattern. In FIG. 1A, the pre-plating pattern 13 is formed only on one side of the substrate 10, but it may be formed on both sides. The planar shape of the substrate 10 is not particularly limited, and may be a rectangle or a circle.

  Hereinafter, the method for forming the pre-plating pattern 13 according to the present embodiment will be described in detail with reference to FIGS. 23A to 23E again. First, a thin base metal film 11 is formed on the entire surface of the substrate 10. Copper (Cu) is preferably used as the material of the base metal film 11, and can be formed by a known method such as electroless plating or sputtering.

  Next, a pre-plating frame 12 made of a resist pattern is formed by photolithography (FIG. 23B). Next, electrolytic plating is performed to selectively grow the base metal film 11 exposed in the opening of the frame 12, thereby forming a line and space pattern integrated with the base metal film 11 (FIG. 23C). )). The line and space pattern can be formed by applying a low current to the frame 12 in a copper sulfate plating solution.

  Here, since all the lines of the line and space pattern on the base metal film 11 are in an electrically connected state, after removing the frame 12 with an organic solvent or the like (FIG. 23 (d)), an extra base metal The film 11 is removed, and the line and space pattern is revealed (FIG. 23E). The base metal film 11 can be removed by wet etching, milling, RIE, or the like. The pre-plating pattern 13 which consists of a line and space pattern is completed by the above.

The ratio of the space width W _S1 to the line width W _L1 of the pre-plating pattern 13 is preferably 1.4 or more. When the ratio of the space width W _S1 to the line width W _L1 is smaller than 1.4, the upper surface of the pattern after the first non-frame plating process (isotropic plating process) described later is not rounded. This is because the yield of the high aspect plating pattern decreases.

The thickness T ₁ of the pre-plating pattern 13 is not particularly limited, but the cross-sectional aspect ratio (T ₁ / W _L1 ) is preferably approximately 1. This is because if the aspect ratio is too low, the short-circuit rate increases, and if the aspect ratio is too high, the resistance value increases even with the same coil thickness. In addition, the upper surface of the pre-plating pattern 13 may be flat as illustrated, may be rounded, or may be dented.

  FIG. 2 is a plan view showing a more specific pattern shape of the pre-plating pattern 13.

  As shown in FIG. 2, the pre-plating pattern 13 includes a spiral pattern 13S and constitutes a basic pattern of a thin film coil. In the figure, four spiral patterns 13S are formed on a part of one substrate, and each is divided into one product. The spiral pattern 13S is not limited to a circular spiral, and may be a rectangular spiral. The outer peripheral end 13 e of the spiral pattern 13 </ b> S is connected to any one of a plurality of wiring patterns 19 extending in the lateral direction, and current is supplied to all the spiral patterns 13 </ b> S via any of the wiring patterns 19.

  Next, as shown in FIG. 1B, a first non-frame plating process is performed in which the pre-plating pattern 13 is isotropically grown while applying a low current in the plating solution 21. “Non-frame” means that the frame 12 for individually forcing anisotropic growth of each line pattern is not used as in the formation of the pre-plating pattern 13 shown in FIG. At this time, the plating solution 21 may be stirred or may not be stirred. By this first non-frame plating step, the pre-plating pattern 13 having a rectangular cross section is grown not only in the vertical direction but also in the horizontal direction, and has a cross-sectional shape in which the upper part is curved. FIG. 1B shows a plating pattern 14 in the middle of growth.

The plating solution 21 is preferably a copper sulfate plating solution. The copper sulfate plating solution preferably contains copper sulfate (CuSO ₄ .5H ₂ O), sulfuric acid (H ₂ SO ₄ ), and chlorine (Cl), and further includes an organic additive that improves the plating film quality. As organic additives, it is possible to use a brightening agent that increases the gloss by making the plating film dense, or a leveler that increases the activation polarization by suppressing the deposition of adsorbed copper ions on the cathode surface and increases the throwing power. it can. As the brightener, a disulfide compound or a sulfur compound can be used. The disulfide compound is, for example, SPS [bis- (3-sulfopropyl) -disulfide disodium: NaO ₃ S (CH ₂ ) ₃ SS ( CH ₂ ) ₃ SO ₃ Na], and the sulfur compound is, for example, HS-C _n. H _2n -SO ₃ (Mercapto alkylsulfonic acid). Examples of the leveler include a surfactant such as PEG (polyethylene glycol).

The first non-frame plating step is continued until the space width W _S2 of the line and space pattern reaches an optimum width that is narrower than the space width W _S1 of the pre-plating pattern 13, as shown in FIG. As a result, the line width _{W L2} of the plating pattern 14 is wider than the line width _{W L1} pre plating pattern 13. There is a slight gap between the widened portion and the substrate 10.

The thickness T ₂ of the plating pattern 14 obtained by the first non-frame plating process, it is not particularly limited as long as the rounded upper surface is obtained, which is 1-3 times the space width of the plating pattern to be finally obtained preferable. If it is thinner than this, the possibility of short-circuiting between adjacent lines after the second non-frame plating process increases, and if it is thicker than this, the cross-sectional shape of the coil tends to become thicker upward, and the cross-sectional area is the same even with the same plating thickness. This is because it becomes smaller and the resistance value becomes larger.

The thickness T ₂ of the plating pattern 14 after the first non-frame plating process is preferably at least twice the space width W _S2 of the line-and-space pattern. If it is twice or more, the production yield of a line and space pattern having a high aspect ratio and a narrow space width can be increased.

  Next, as shown in FIG. 1 (d), a second non-frame plating step in which a higher potential than before is applied in the same plating solution, and the plating pattern 14 is anisotropically grown while flowing a large current. To implement. As a result, a thin metal ion layer 17 having a certain thickness or more is generated on the surface of the plating pattern 14 in contact with the plating solution 21.

  FIG. 3 is a schematic diagram for explaining the metal ion diluted layer 17.

  As shown in FIG. 3 (a), when a pair of electrodes 22a and 22b are installed in the plating solution 21, and positive and negative potentials are respectively applied between them, as shown in FIG. 3 (b), the cathode Nearby metal ions (positive ions) are attracted to the cathode side (electrode 22b side) by the potential, receive electrons on the electrode surface, and sequentially deposit on the cathode surface. In such an electroplating phenomenon, the deposition rate of metal atoms increases when a high potential is applied, so that the supply of metal ions from offshore to the vicinity of the cathode is not in time, and the metal is contained in the plating solution 21 (metal ion aqueous solution) near the cathode. A very dilute region of ion concentration is formed. This region is called “electric double layer” in the field of capacitors, but in the present invention, it is called “diluted metal ion layer”. The metal ion concentration in the diluted metal ion layer 17 is such a concentration that the plating does not grow even when an electric potential is applied, and strictly speaking, it has a concentration gradient that becomes deeper as the distance from the interface increases. The diluted metal ion layer 17 tends to be thicker as the applied potential is higher.

  The present invention pays attention to the generation of the diluted metal ion layer 17 and, in combination with the agitation of the plating solution described later, allows selective plating growth in one direction without providing a frame forcing the anisotropic growth of plating. It is realized.

  When shifting from the first non-frame plating step to the second non-frame plating step, it is necessary to instantaneously switch the potential applied to the plating pattern 14 from a low potential to a high potential. This is because it is necessary to prevent the metal ion dilute layer 17 from completely disappearing even if it is temporary. Although the metal ion dilute layer 17 is also generated in the first non-frame plating process, its thickness is very thin and easily broken. By increasing the thickness of such a thin metal ion layer 17 without breaking it even at the moment of switching, it is possible to reliably suppress lateral plating growth.

  In the first non-frame plating step, as shown in FIG. 1E, the plating solution 21 thereabove is stirred at an appropriate stirring speed while supplying a large current to the plating pattern 14. The dilute metal ion layer 17 is substantially an insulating layer and covers the entire surface of the plating pattern 14, but if left in this state without stirring at all, dielectric breakdown occurs with a certain probability, and its position is localized. Plated on. By forming a large number of this partial plating growth at random, it becomes a so-called plating burn state in which the unevenness of the surface is remarkable.

  However, when the thin metal ion layer 17 is partially removed by stirring the plating solution, the metal ions are supplied only to that portion, so that the plating can be grown in one direction. In this case, by appropriately stirring the plating solution 21 above the plating pattern, the metal ion dilute layer 17 in contact with the curved surface of the upper part (head) of the plating pattern is partially destroyed, and this portion is directed upward. The plating growth continues. Plating growth on the lower side surface of the plating pattern 13 in which the metal ion diluted layer 17 has not been destroyed is suppressed.

The thickness W ₀ of the diluted metal ion layer 17 is predicted to be equal to or more than half the space width W _S2 (W _S2 / 2) of the final line and space pattern. If the space width W _S2 is more than twice the thickness of the metal ion dilute layer 17, there is a region of normal metal ion concentration between the left and right metal ion dilute layers 17, which is anisotropic plating. This is because it can be a hindrance to growth. Therefore, in order to ensure the anisotropic plating growth, it is necessary to make the thickness of the diluted metal ion layer 17 more than half of the space width _WS2 . Not become W _{S2 / 2} = W ₀ is W ₀ of the removed portion near the metal ion lean layer by agitation, repeating the larger or smaller than W ₀ little with fluctuations of the plating solution. Therefore, the dilute metal ion layer that is in contact with the upper curved surface of the plating pattern on the outer side of 2W ₀ between the lines is substantially removed by stirring. In this state, the metal ion dilute layer 17 already formed by applying a high potential is protected by the newly formed metal ion dilute layer 17, so that metal ions are not supplied to this portion, and the metal ion dilute layer is not provided. Layer 17 is maintained. Such a phenomenon is a peculiar phenomenon which occurs at the time of forming the line and space pattern, and is extremely effective as a method for narrowing the space width.

  The composition of the plating solution used in the second non-frame plating process is not particularly limited, and any composition can be plated and grown in a high aspect. However, since the optimal combination of the current density and the stirring speed varies depending on the composition of the plating solution, it is important to manage the composition of the plating solution. Since the plating solution used in the first non-frame plating step is used as it is in the second non-frame plating step, the composition needs to be a suitable composition also in the second non-frame plating step.

In the present embodiment, it is important that the space width W _S1 of the first pre-plating pattern 13 is set wider than the space width W _S2 of the final plating pattern. This is because a line pattern having a rectangular or trapezoidal cross-sectional shape is formed by isotropic plating to form a roundness on the upper surface, and at the same time, it is necessary to narrow the space to an appropriate space width. By adjusting the pre-plating pattern 13 to a shape suitable for anisotropic plating, the thickness and surface state of the plating pattern can be reliably controlled.

  The metal ion dilute layer 17 is destroyed from the top of the curved surface by the stirring of the plating solution, and the second non-frame plating process is started in order to adjust the fracture region of the metal ion dilute layer 17 by the strength of the stirring. Sometimes it is necessary to round the top surface of each line pattern. If the upper surface of each line pattern is flat, the metal ion diluted layer 17 generated in the upper part of the space between adjacent lines is destroyed, and the metal ion diluted layer 17 generated in the lower part is destroyed. This is because the conditions are almost the same, and it becomes very difficult to destroy only the thin metal ion layer 17 at the top of each line pattern by stirring the plating solution.

Then, as shown in FIG. 1 (f), the plating pattern stops supplying the current at the time of the growth to a desired thickness (height) T _3, and ends the second non-frame plating process. Thus, the plating pattern 15 composed of a line and space pattern having a high aspect ratio is completed.

  FIG. 4 is a schematic cross-sectional view showing the structure of the plating pattern in more detail.

As shown in FIG. 4, the plating pattern 15 composed of a high aspect line and space pattern includes a pre-plated layer having a _first line width W _L1 , a first space width W _S1 , and a first thickness T _1. 15a, a second line width W _L2 wider than the first line width W _{L1, a} second space width W _S2 narrower than the first space width W _S1 , and a thickness thicker than the first thickness T1. A first non-frame plating layer 15b having a thickness T2 of ₂ , a curved surface at the top, and covering the top and side surfaces of the pre-plating layer 15a, a second line width _WL2 , and a second space width A second non-frame plating layer 15c having W _S2 and a third thickness T ₃ larger than the second thickness T ₂ and having a curved surface at the top and covering the first non-frame plating layer 15b; Have.

  The pre-plated layer 15a is a base metal film for plating formation, and the first non-frame plated layer 15b is a film obtained by isotropically plating and growing the pre-plated layer 15a, and the second non-frame plated layer 15c. Is a film obtained by anisotropically growing the first non-frame plating layer 15b. These layers are made of the same material (Cu), but when the cross section thereof is viewed with a micrograph, it is possible to clearly distinguish the boundaries between the layers.

  Although the plating apparatus for implementing the said anisotropic plating method is not specifically limited, For example, the plating apparatus shown below can be used.

  FIG. 5 is a schematic diagram showing a first example of the configuration of the plating apparatus.

  As shown in FIG. 5, the plating apparatus 30 is a face-up type, and a negative potential is applied to the workpiece 33 (the substrate 10 on which the pre-plating pattern 13 is formed) fixed on the stage 32 in the plating rod 31. Applied. A plus-side electrode 34 is disposed at the center of the plating rod 31 and is disposed so as to face the upper surface of the work 33. A paddle 35 that is one of the stirring members is disposed between the work 33 and the plus side electrode 34. The paddle 35 is a rod-shaped body having a regular triangle cross section, and one side of the triangle is, for example, 10 mm. Such paddle 35 repeats advancing and retreating in a direction parallel to the substrate surface indicated by the arrow, whereby the plating solution 21 located in front of the workpiece surface is agitated.

  A new plating solution or a circulating plating solution (copper ions) in the plating vessel 31 may be positively supplied between the plating vessels 31 or the electrodes, or the supply of the plating solution may be refused. If the plating solution is sufficiently supplied, the plating conditions are always constant, and there is an advantage that the space width hardly changes even when the plating progresses. On the other hand, when the supply of the plating solution is cut off, the copper ions in the plating solution gradually decrease, and the space width tends to increase with the progress of plating. In this case, care must be taken so that the copper ion concentration does not enter the plating burn area under the plating conditions by the end of plating. Furthermore, by adjusting the supply amount of the plating solution (copper ions), it is also possible to adjust the amount of space width (speed) that tends to spread with the progress of plating.

  FIG. 6 is a schematic diagram showing a second example of the configuration of the plating apparatus.

  As shown in FIG. 6, the plating apparatus 40 is a so-called vertical type, and a negative potential is applied to a workpiece 33 provided in a vertical state in a plating rod 41. A plus side electrode 34 is disposed at a position facing the front surface of the work 33, and the plus side electrode 34 is also provided in a vertical state like the work 33. A paddle 35 is disposed between the work 33 and the plus electrode 34. As the paddle 35 repeats advancing and retreating in a horizontal direction parallel to the substrate surface (a direction perpendicular to the paper surface in the drawing), the plating solution 21 positioned in front of the workpiece 33 is agitated. The distance from the surface of the work 33 to the paddle 35 is preferably 15 to 30 mm.

  Further, as shown in the figure, a plating solution supply port 42 is provided at the bottom of the plating vessel 41, and a new plating solution or a plating solution (copper ions) circulating in the plating vessel 41 is supplied from the plating solution supply port 42. It may be positively supplied or the supply of the plating solution may be refused. When a new plating solution is supplied, excess plating solution overflows from the upper end of the partition plate 43 and is discharged from the plating solution discharge port 45 through the outer plating solution discharge path 44.

  The plating apparatus 40 described above can carry out an anisotropic plating method in the same manner as the plating apparatus 30 shown in FIG. 5, and by adjusting the supply amount of the plating solution (copper ions), the plating progresses. The spread amount (speed) of the space width that tends to spread can be adjusted.

  FIG. 7 is a schematic diagram showing a third example of the configuration of the plating apparatus, and FIG. 8 is a schematic perspective view showing the configuration of the stirring grid in FIG.

  As shown in FIGS. 7 and 8, the plating apparatus 50 is a so-called vertical type plating apparatus, and particularly uses a stirring grid 51 instead of the paddle 35. The stirring grid 51 is a plate-like member having a grid structure, and is provided so as to face the workpiece 33 in the plating solution 21. The distance from the surface of the work 33 to the surface of the stirring grid 51 is preferably 30 to 50 mm. Since it is empirically known that the stirring state of the plating solution deteriorates if the stirring grid 51 is too close to the surface of the workpiece 33, an appropriate distance is required between the stirring grid 51 and the workpiece 33.

  The agitation grid 51 agitates the plating solution 21 positioned in front of the workpiece surface by repeating a rotational motion of, for example, a rotation radius of 20 mm in a plane parallel to the substrate surface. The motion of the stirring lattice 51 is not limited to the rotational motion, and may be a periodic swing in one direction or a swing of 1 / f fluctuation. Note that the unidirectional swing is a one-dimensional advance / retreat movement, and the in-plane rotational movement is a two-dimensional advance / retreat movement.

As an example of the size of the stirring grid 51, the size of the grid area (width W _m1 × length W _m2 ) is 200 mm × 200 mm, and the size of the grid hole (width W _m3 × length W _m4 ) is 13 mm × 13 mm. The beam width W _m5 is 2 mm, and the thickness W _m6 is 10 mm. In addition, what is necessary is just to set the size of the stirring grid 51 suitably according to stirring conditions. However, the stirrer lattice 51 is required to have a certain degree of rigidity so as not to be bent by water pressure.

  In the present embodiment, it is preferable to arrange the stirring grid 51 almost directly above the plating solution supply port 42 provided at the bottom of the plating rod 41. According to this configuration, a new plating solution can be efficiently stirred, and a certain space width can be ensured even when plating progresses.

  In the plating apparatus using the stirring grid 51 shown in FIG. 7, the influence of both the electric field and the stirring is always applied to the plating pattern, so that it is presumed that the diluted metal ion layer is always open. On the other hand, in the plating apparatus using the paddle 35 shown in FIG. 6, only the influence of the electric field is always applied, and the influence of stirring is intermittently applied. Therefore, it is assumed that the metal ion diluted layer repeats opening and closing. The Therefore, it is considered that the use of the paddle 35 facilitates maintaining the distance between the lines of the plating pattern and promotes anisotropic plating growth.

  FIG. 9 is a schematic diagram illustrating a fourth example of the configuration of the plating apparatus.

  As shown in FIG. 9, this plating apparatus 60 is a so-called vertical type plating apparatus, and is characterized by stirring the plating solution by swinging the workpiece 33 without using a stirring member. The workpiece 33 repeats, for example, rotational movement in a plane parallel to the substrate surface, whereby the plating solution 21 located in front of the workpiece surface is agitated. The movement of the workpiece is not limited to a rotational movement, and may be a periodic swing in one direction or a swing of 1 / f fluctuation.

  The plating apparatus 60 described above can carry out an anisotropic plating method in the same manner as the plating apparatus 30 shown in FIG. 5, and by adjusting the supply amount of the plating solution (copper ions), the progress of plating can be achieved. The spread amount (speed) of the space width that tends to spread can be adjusted. In particular, the metal ion dilute layer on the substrate can be uniformly and evenly destroyed without using any stirring member such as a paddle or a stirring grid, thereby forming a plating pattern consisting of a line and space pattern having a high aspect ratio. can do. Also, the plating apparatus can be configured at low cost.

  The optimum conditions for plating in the second non-frame plating step are those that are slightly closer to the good region from the plating burn region. Further, as the anisotropic plating growth proceeds, it is preferable to increase the current density in a region where the plating is not burnt, decrease the stirring speed, or perform them simultaneously so that the space width is increased.

FIG. 10 is a graph showing the relationship between the current density and the stirring speed, in which the horizontal axis represents the current density (A / 100 cm ² ) and the vertical axis represents the stirring speed (rpm). The stirring speed means how many times the paddle reciprocates per minute. In the graph, “◯” indicates a sample with a good plating result, “×” indicates a sample with a poor plating result, and “#” indicates a sample with a short plating result. The unit area of current density of 100 cm ² means a planar area when the plating pattern is viewed from directly above (directly in front).

  As shown in FIG. 10, when the current density of the current flowing through the plating pattern is constant, plating burn occurs when the stirring speed is low, and a good plating pattern is formed from a certain stirring speed when the stirring speed is increased. When a region appears and the stirring speed is further increased, a region where a short circuit occurs between adjacent lines from a certain stirring speed appears. Thus, the state of the plating pattern corresponds to any one of “plating burn region”, “good region”, and “short region” depending on the plating conditions.

  On the other hand, when the stirring speed is constant, the higher the current density, the higher the aspect ratio of the good region and the better the stirring speed margin. That is, when the current density is increased, the space width of the line-and-space pattern is increased, and conversely, when the current density is decreased, the space width is decreased. If the copper ion concentration in the plating solution is increased, the deposition rate of plating is increased, and the same effect as when the current density is increased or the stirring speed is increased is obtained. Further, increasing the concentration of the brightener in the plating solution has the same effect as when the current density is increased or the stirring speed is increased.

  Thus, the higher the current density (applied potential), the thicker and stronger the metal ion dilute layer, and the higher the stirring speed necessary for partial destruction of the metal ion dilute layer. However, if the stirring speed is too high, a short circuit occurs, so there is an optimal combination condition of current density and stirring speed. Moreover, when the current density is increased, the allowable range of the stirring speed tends to be increased. The anisotropic plating method according to the present invention requires precise and uniform stirring in consideration of such conditions. The above results are consistent with the metal ion diluted layer model shown in FIG.

  FIG. 11 is an optical micrograph showing the surface state of plating.

  As shown in FIG. 11 (a), when the plating pattern is grown correctly, a clean line and space pattern having a very narrow pitch is formed. However, when plating burn occurs, as shown in FIG. 11B, large and small irregularities are generated, resulting in a pattern in which the line width is disturbed. In the case of a short circuit, there is no line space (space) in FIG.

  As described above, the anisotropic plating method according to the present embodiment is generated on the surface of the metal film for plating formation or the film formed on the surface of the metal film when a film is formed by applying an electric current. Since the metal ion dilute layer 17 existing in the direction in which the plating solution is desired to be selectively grown in the plating solution dilute layer 17 is partially destroyed by stirring of the plating solution, the coating is formed. Therefore, a line-and-space pattern having a space width narrower than the resolution limit of photolithography, a wide line width, and a high aspect ratio can be formed without causing a short circuit.

  In addition, the anisotropic plating method according to the present embodiment is obtained by growing the pre-plating pattern in the first non-frame plating step so that the metal ion diluted layer 17 is correctly formed, and then forming the second non-plating pattern. Since anisotropic plating growth is performed in the frame process, a line and space pattern with a high aspect ratio can be formed at a very narrow pitch, and the shape of the line and space pattern can be controlled with high accuracy. Furthermore, the anisotropic plating method according to the present embodiment performs plating by applying a large current after the space width between adjacent line patterns is made narrower than the space width that can be resolved with a resist. The area can be increased. Therefore, the direct current resistance of the plating pattern can be reduced, and heat generation and power consumption can be reduced.

   Next, an anisotropic plating method according to the second embodiment of the present invention will be described. The anisotropic plating method according to the second embodiment is characterized by using an external frame 16 that regulates the plating growth in the lateral direction of the outermost line pattern of the line and space pattern. Although not explicitly shown in the first embodiment, when no frame is used, the outermost line pattern in which there is no adjacent line pattern is not only the metal ion diluted layer 17 generated on the curved surface above the pattern, Even the thin metal ion layer 17 generated on the inner side of the innermost periphery and the side surface of the outermost outermost pattern is destroyed, whereby the plating growth in the lateral direction proceeds and tends to be thicker than other line patterns. It can be seen. Therefore, in the second embodiment, control is performed so that the outermost line pattern has the same thickness as other line patterns.

  FIG. 12 is a schematic diagram for explaining the anisotropic plating method according to the second embodiment of the present invention.

In the anisotropic plating method according to the present embodiment, first, as shown in FIG. 12A, the pre-plating pattern 13 is formed on the surface of the substrate 10, and then the external frame 16 is formed. The outer frame 16 is a resist pattern that surrounds the outermost line pattern of the pre-plating pattern. Outer frame 16 has a perpendicular side surface to the main surface of the substrate 10, the side surface is formed at a position at a predetermined space width W _S3 from the side surface of the outermost line pattern. Although details will be described later, it is preferable that the space width W _S3 is slightly wider than the half width (W _S1 / 2) of the space width W _S1 of the line and space pattern.

  Thereafter, as shown in FIGS. 12B to 12F, the first non-frame plating step and the second non-frame plating step are sequentially performed. This process is basically the same as in the first embodiment.

  When the external frame 16 is not used, the metal ion diluted layer 17 covering the side surface of the outermost line pattern in which no adjacent line pattern is present is also destroyed, the plating growth spreads in the lateral direction, and the width of the line pattern is different from that of the other line pattern. The line width becomes thicker than the line pattern. However, in this embodiment, since the side surface of the outer frame 16 prevents the metal ion diluted layer 17 from being destroyed, lateral plating growth can be suppressed.

On the other hand, as shown in FIG. 12 (e), when there is an external frame 16, it becomes a shadow and it becomes difficult for waves during stirring to reach the metal ion diluted layer 17 near the external frame 16. Therefore, so that all of the line pattern grows evenly plating, half of the width of the space width W _S4 line and space pattern of space width W _S2 (W _{S2 / 2)} slightly wider than to the metal ions in the vicinity of the top It is preferable to increase the range in which the diluted layer 17 is destroyed.

  Thereafter, if necessary, the third non-frame plating step of removing the external frame 16 and applying the same high potential as the second non-frame plating step may be performed. In the third non-frame plating process, the line pattern tends not to thicken in the horizontal direction. This is because, since the plating pattern is already thick, the influence of the agitation of the plating solution does not reach the innermost part of the innermost periphery and the lower part of the outermost outermost line pattern, and the metal thin layer is not easily destroyed. Therefore, desired anisotropic plating growth can be expected.

  FIG. 13 is a plan view showing a more specific pattern of the outer frame 16, and corresponds to the spiral pre-plating pattern 13 shown in FIG.

  As shown in FIGS. 13A and 13B, the outer frame 16 has a shape surrounding the outermost periphery side and the innermost periphery side of the spiral pre-plating pattern 13, and is outside the outermost periphery of the spiral pattern 13S. The first portion 16a provided on the outer periphery and the second portion 16b provided inside the outermost periphery. And as shown in FIG.13 (b), the pre-plating spiral pattern 13S is arrange | positioned in the annular | circular shaped area | region where the external frame 16 does not exist. The innermost circumference of the spiral pattern 13S can also be interpreted as the outermost line and space pattern.

As described above, since the anisotropic plating method according to the present embodiment uses the external frame 16, in addition to the effects of the invention according to the first embodiment, the side surface of the outermost line pattern of the line and space pattern is used. The appearing metal ion dilute layer 17 can be prevented from being destroyed by the stirring of the plating solution, thereby preventing the outermost line pattern from becoming thicker than the other line patterns. In particular, since the outer frame 16 is formed before the first non-frame plating step is started, the step of forming the outer frame 16 is interposed between the first non-frame plating step and the second non-frame plating step. First, switching from the first non-frame plating process to the second non-frame plating process can be performed continuously.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in the range.

  For example, in the above-described embodiment, the spiral pattern is exemplified as an example of the line and space pattern. However, the present invention is not limited to the spiral pattern, and can be applied to various line and space patterns such as an array of a plurality of linear patterns. It is.

Example 1
Using a face-up type plating apparatus shown in FIG. 5, one side of a 6-inch silicon wafer was plated in a copper sulfate plating bath to form 2000 spiral patterns. Here, the paddle of the plating apparatus is composed of a rod-shaped body having a cross-sectional shape of a regular triangle having a side of 10 mm, and its length is 200 mm. Further, a disc having a diameter of 15 cm was used as the positive electrode, and phosphorous copper (phosphorus concentration 500 ppm) was used as the material. The distance from the wafer surface to the bottom surface of the paddle was 10 mm, and the distance from the wafer mounting surface to the plus side electrode was 50 mm. The paddle stroke was set to 180 mm so that the wafer could be swung from one end to the other.

The components of the copper sulfate plating solution were 200 g / L CuSO ₄ , 200 g / L H ₂ SO ₄ , 30 mg Cl ⁻ , 10 g / L chlorine ion (Cl), and about 5 mg / L as a brightener. L SPS (disulfide compound) and PEG (polyethylene glycol, average molecular weight: 15000) as a leveler, and the temperature of the plating solution was maintained at 40 ° C.

  In forming the spiral pattern, a Cu film having a thickness of 0.2 μm was first formed by sputtering on the entire surface of one main surface of the silicon wafer. Next, a dry film resist was formed on the surface of the Cu film, and the dry film resist was patterned by photolithography and dry etching to form a resist pattern.

  Next, a plating process (frame plating) was performed using the resist pattern as a frame, and a spiral pattern was plated and grown on the Cu film until the thickness became 25 μm. Thereafter, the resist pattern was removed, and unnecessary Cu film was removed by milling to complete a pre-plating pattern. Furthermore, an external frame was formed around the pre-plating pattern. The external frame was formed by forming a dry film resist having a thickness of 150 μm and then patterning the dry film resist by photolithography and dry etching.

Next, a first non-frame plating process was performed. The plating conditions at this time were a current density of 5 A / 100 cm ² , a paddle reciprocation count of 80 reciprocations / min, and a space width of 12 μm. As a result, a plating pattern having a thickness of 18 μm was obtained.

Next, a second non-frame plating process was performed. The plating conditions at this time were a current density of 50 A / 100 cm ² , a paddle reciprocation frequency of 80 reciprocations / min, and an overall thickness of about 140 μm.

  FIG. 14 is a schematic diagram showing a thumbnail of the optical micrograph of each sample of the spiral plating pattern on the wafer and the thickness of the pattern. FIG. 15 is a detailed SEM image photograph of the spiral plating pattern.

  As shown in FIG. 14, the pattern thickness of each sample at nine points on the wafer was within a range of 137 to 144 μm although there was some variation, and the average thickness was 139 μm, and the range was 9 μm. Also, in the electron micrograph of FIG. 15, it was confirmed that a spiral pattern having a high aspect ratio and a very narrow pitch was formed.

(Example 2)
A third non-frame plating process was performed on the wafer obtained in Example 1 above. In the third non-frame plating step, the external frame was peeled off, the current density was 60 A / 100 cm ² , the paddle reciprocation was 100 reciprocations / minute, and the total thickness including the pre-plating pattern was about 180 μm. .

  FIG. 16 is a schematic diagram showing a thumbnail of the micrograph of each sample of the spiral plating pattern on the wafer and the pattern thickness. FIG. 17 is a detailed SEM image photograph of the spiral plating pattern.

  As shown in FIG. 16, the pattern thickness of each of the nine samples on the wafer was slightly varied but was within the range of 177 to 189 μm, the average thickness was 183 μm, and the range was 12 μm. Also, in the electron micrograph of FIG. 17, it was confirmed that a spiral pattern having a high aspect ratio and a very narrow pitch was formed.

(Example 3)
An anisotropic plating method with a coil pattern thickness of 140 μm was performed under the same conditions as in Example 1. At that time, the current density supplied to the plating pattern in the second non-frame plating step was used as a parameter, and measurement was performed for each of 30, 40, 50, and 60 (A / 100 cm ² ).

  FIG. 18 is a graph showing the relationship between the current density and the space width of the plating pattern.

  As is apparent from FIG. 18, it can be seen that the space width of the plating pattern composed of the line and space pattern is proportional to the increase in current density. Accordingly, it has been clarified that the space width can be widened by increasing the current density, and conversely, the space width can be narrowed by decreasing the current density. It is considered that when the applied current density (potential) increases, the metal ion diluted layer becomes thicker and stronger, and the space width increases accordingly.

Example 4
An anisotropic plating method with a coil pattern thickness of 140 μm was performed under the same conditions as in Example 1. At that time, in the second non-frame plating step, the stirring rate of the plating solution was used as a parameter, and measurement was performed for each of 80, 90, and 100 (rpm). The current density at this time is 50 A / 100 cm ² .

  FIG. 19 is a graph showing the relationship between the stirring speed and the space width.

  As shown in FIG. 19, it can be seen that the space width of the plating pattern composed of the line and space pattern is inversely proportional to the increase in the stirring speed. Therefore, it was revealed that the space width can be narrowed by increasing the stirring speed, and conversely, the space width can be widened by decreasing the stirring speed. It is considered that when the stirring speed is increased, the fracture region of the metal ion dilute layer is widened, so that the space width is narrowed.

(Example 5)
An anisotropic plating method with a coil pattern thickness of 140 μm was performed under the same conditions as in Example 1. At that time, in the second non-frame plating step, the concentration of the brightener (SPS) in the plating solution was used as a parameter, and measurement was performed for each condition of 1, 5, and 10 (mg / L).

  FIG. 20 is a graph showing the relationship between the SPS concentration in the plating solution and the space width.

  As shown in FIG. 20, it can be seen that the space width of the plating pattern composed of the line and space pattern is proportional to the increase in the SPS concentration. Therefore, it was revealed that the space width can be widened by increasing the SPS concentration, and conversely, the space width can be narrowed by decreasing the SPS concentration. As the SPS concentration increases, the metal ion dilute layer becomes thicker and stronger, as is the case with the current density, and the space width is considered to increase accordingly.

(Example 6)
An anisotropic plating method with a coil pattern thickness of 140 μm was performed under the same conditions as in Example 1. At that time, in the second non-frame plating step, the copper sulfate concentration in the plating solution was used as a parameter, and measurement was performed for each of 150, 200, and 250 (g / L).

  FIG. 21 is a graph showing the relationship between the copper sulfate concentration in the plating solution and the space width.

As shown in FIG. 21, it can be seen that the space width of the plating pattern composed of the line and space pattern is inversely proportional to the increase in the copper sulfate concentration. Therefore, it was revealed that the space width can be narrowed by increasing the copper sulfate concentration, and conversely, the space width can be widened by decreasing the copper sulfate concentration. It is considered that when the copper sulfate concentration is high, the metal ion dilute layer is difficult to be formed, and the space width is narrowed.
(Example 7)
The basic plating conditions were the same as in Example 1, and the production yield of the product was determined when the line width of the pre-plating pattern was fixed at 25 μm and the space width was changed within the range of 15 to 60 μm. The space width of the pre-plating pattern was changed in increments of 5 μm. The results are shown in Table 1.

  As is clear from Table 1, when the space width was 30 μm or less, the yield was 70% or less, and the yield was very low. On the other hand, when the space width was 35% or more, the yield was 95% or more, which was a very high yield. From the above results, the ratio of the space width to the line width of the pre-plating pattern is preferably 1.4 or more, and if it is less than this, the roundness of the pattern surface after the first frame plating process cannot be obtained, It was revealed that the yield for obtaining a good space width decreases.

(Example 8)
The basic plating conditions were the same as in Example 1 above, and the short-circuit rate and resistance value were obtained when the aspect ratio of the pre-plating pattern was changed within the range of 0.1 to 5.0. The resistance value was a standard value when the good value was 100. The results are shown in Table 2.

  As apparent from Table 2, the short-circuit rate was 1% or more when 0.5 or less, and 0% when 0.8 or more. Further, the resistance value was 100 when 1.2 or less, and 102 or more when 1.5 or more. From this result, it was found that when the thickness of the pre-plating pattern is thin, the short-circuit rate is high, and when it is thick, the resistance value increases even with the same pattern thickness.

Example 9
The basic plating conditions were the same as in Example 1, and the resistance value was determined when the line width of the pre-plating pattern was constant and the space width was changed within the range of 5.0 to 35 μm. The results are shown in Table 3.

  As is apparent from Table 3, the resistance value was short (S) when the space width was 8.0 μm or less, became 100 when the space width was 11.2 to 33.6 μm, and became high at 110 when the space width was 35 μm. . From this result, it was found that if the space width of the pre-plating pattern is narrow, the probability of short-circuiting increases, and if the space width is too wide, the resistance value increases.

(Example 10)
The plating apparatus shown in FIGS. 6, 7, and 9 is used to perform plating on one side of a 6-inch silicon wafer to form 2000 spiral patterns, and anisotropic growth in the case of different stirring methods. A comparison of ease was performed. The plating conditions in the apparatus of FIG. 6 were almost the same as those in Example 1. That is, the paddle of the plating apparatus is made of a rod-like body having a cross-sectional shape of a regular triangle having a side of 10 mm, and its length is 200 mm. Further, a disc having a diameter of 15 cm was used as the positive electrode, and phosphorous copper (phosphorus concentration 500 ppm) was used as the material. The distance from the wafer surface to the bottom surface of the paddle was 20 mm, and the distance from the wafer mounting surface to the plus side electrode was 50 mm. The paddle stroke was set to 180 mm so that the wafer could be swung from one end to the other. Furthermore, the plating current density in the first and second non-frame plating steps was set to 30 A / 100 cm ² .

In the apparatus of FIG. 7, it was made the same as the plating process conditions using the apparatus of FIG. 6 except that the stirring grid was controlled so as to perform the in-plane rotational motion with a radius r = 20 mm. The size of the stirring grid 51 is 200 mm × 200 mm for the size of the lattice region (width W _m1 × length W _m2 ), the size of the lattice hole (width W _m3 × length W _m4 ) is 13 mm × 13 mm, and the beam width W of the lattice. _m5 was 2 mm, and thickness W _m6 was 10 mm. The distance from the wafer surface to the surface of the stirring grid was 35 mm. Other conditions were the same as the plating conditions in the apparatus of FIG. In the apparatus of FIG. 9, it was made the same with the plating conditions in the apparatus of FIG. 7 except that the workpiece was controlled to perform an in-plane rotational motion with a radius r = 20 mm.

  FIG. 22 is a graph showing the relationship between the plating time and the aspect ratio of the plating pattern, where the horizontal axis is the plating time (minutes), and the vertical axis is the aspect ratio of the plating pattern (increase in plating film thickness / increase in plating width). The average value of 5 points of (quantity) is shown. As is clear from FIG. 22, the aspect ratio of the plating pattern is greatest when a paddle is used, and the next is when the substrate is swung. That is, it was found that when using a paddle, the anisotropic growth is most likely, followed by the substrate swing and the stirring lattice.

(Example 11)
Using the plating apparatus shown in FIGS. 6, 7, and 9, plating is performed on one side of a 6-inch silicon wafer to form 2000 spiral patterns, and the plating pattern manufacturing yield when the stirring method is different. Asked. At that time, the line width of the pre-plating pattern was 25 μm and the space width was 50 μm. Further, the current density supplied to the plating pattern in the second non-frame plating step was set to 30 A / 100 cm ² . The results are shown in Table 4.

  As is apparent from Table 4, the yield when using the paddle was 100%, whereas the yield when the substrate was swung was 75%, and the yield when the stirring grid was 60%. That is, it was found that the yield was the best when the paddle was used, followed by the substrate swing and the stirring grid.

DESCRIPTION OF SYMBOLS 10 Substrate 11 Base metal film 12 Frame 13 Pre-plating pattern 13e Peripheral edge 14 of spiral pattern (first) plating pattern 15 (second) plating pattern 15a Pre-plating layer 15b First non-frame plating layer 15c Second non-frame plating layer 16 External frame 17 Metal ion dilute layer 19 Wiring pattern 21 Plating solution 22a Plus electrode 22b Minus electrode 30 Plating device 31 Plating bar 32 Stage 33 Work 34 Plus side electrode 35 Paddle (stirring member)
40 Plating apparatus 41 Plating plate 42 Plating solution supply port 43 Partition plate 44 Plating solution discharge path 45 Plating solution discharge port 50 Plating device 51 Stirring grid (stirring member)
60 plating apparatus _{W L1, W L2} line width _{W m1} grating region width _{W m @ 2} grid area vertical width _{W m3} longitudinal width of the horizontal width _{W m4} grid holes of the grid holes _{W m5} lattice beam width _{W m6} thickness W of the stirring lattice of _{S1, W S2, W S3,} W S4 space width _{T 1,} T 2, _{T 3} pattern thickness

Claims (10)

Forming a pre-plating pattern including a first line-and-space pattern having a first line width, a first space width, and a first thickness on a main surface of the substrate;
In a state where the substrate is immersed in a plating solution, a first current is applied to the pre-plating pattern, and the pre-plating pattern isotropically formed without a frame forcing the anisotropic growth of each line pattern individually. Plating growth has a second line width that is wider than the first line width, a second space width that is narrower than the first space width, and a second thickness that is thicker than the first thickness. And forming a first plating pattern including a second line-and-space pattern having a curved surface on top of each line pattern;
While a second current larger than the first current is passed through the first plating pattern while the substrate is immersed in the plating solution, a thin layer of metal ions is generated on the surface of the first plating pattern. The first plating is performed in a state where there is no frame for individually forcing anisotropic growth of each line pattern by stirring the plating solution and partially destroying the diluted metal ion layer on the upper part of each line pattern. A second plating pattern including a third line and space pattern having a third thickness larger than the second thickness and having a curved surface on top of each line pattern by anisotropically plating the pattern. And forming a process ,
In the step of forming the second plating pattern, the plating solution agitating member is disposed above the main surface of the substrate, and the agitating member is repeatedly advanced and retracted in a direction parallel to the substrate to thereby remove the plating solution. An anisotropic plating method characterized by stirring and thereby partially destroying the metal ion dilute layer above each line pattern . Before forming the first plating pattern, further comprising the step of forming an outer frame surrounding at least the outside of the first line and space pattern ;
The outer frame is a resist pattern formed on the main surface of the substrate so as not to contact the first line and space pattern,
The outer frame has a vertical side surface to said major surface of said substrate, said side being formed on the outermost side from a position at a third space width of the line pattern of the first line and space pattern The anisotropic plating method according to claim 1 . The anisotropic plating method according to claim 2 , wherein the third space width is wider than the second space width. The cross-sectional shape of the forming direction of each line pattern of the first line and space pattern is arcuate, in the step of forming a second plating pattern, claims, characterized in that to the plating growth maintaining circular arc The anisotropic plating method according to any one of 1 to 3 .   The anisotropic plating method according to any one of claims 1 to 4, wherein the plating solution is a copper sulfate plating solution containing copper ions and a brightener. The current density of the first current is 3 to 20 A / 100 cm ² ;
The anisotropic plating method according to claim 1, wherein a current density of the second current is 30 to 70 A / 100 cm ² . The anisotropic stirring method according to any one of claims 1 to 6, wherein the stirring member is a paddle made of a rod-shaped body having a triangular cross section. The anisotropic plating method according to claim 1 , wherein the stirring member is a stirring lattice made of a plate-like member having a lattice structure. 9. The method according to claim 1 , wherein the substrate itself is repeatedly moved back and forth in a direction parallel to the substrate to stir the plating solution, thereby partially destroying the thin layer of metal ions on each line pattern. anisotropic plating method according to an item or. The anisotropic plating method according to claim 1 , wherein the first to third line and space patterns are spiral patterns.