TWI518213B - Method for forming conductive structure - Google Patents

Description

Method for forming conductive structure

The present invention relates to a method of forming a conductive structure, and more particularly to forming a plurality of via plugs on the inside, and having a plurality of electrode pads on the surface and/or having a via plug connected thereto A conductive structure of a rewring structure, and the conductive structure can be used for three-dimensional packaging of semiconductor wafers using the via plugs, the through-hole plugs vertically extending through the conductive structure.

The invention also relates to a plating apparatus and a plating method for filling a metal into a plurality of via holes in a manufacturing process of an interposer or a spacer, the insert or the spacer The interior has a number of via plugs that extend vertically through its structure and can be used for so-called three-dimensional packaging of semiconductor wafers.

Three-dimensional packaging techniques involving laminating a plurality of semiconductor wafers into multilayer packages are quite attractive, especially as techniques for achieving high-density large-scale integrated circuit (LSI) packages to provide smaller sizes and More efficient electronics. A wire bonding method for laminating a plurality of semiconductor wafers has been actually used and is currently Still used to provide high capacity products (such as packaging for flash memory products). However, the disadvantage of this wire bonding method is that the wires used to connect the plurality of electrodes have a length of the millimeter level, which is much longer than the interconnect length of the wafer, so when wire bonding is applied to devices that process high-speed signals (such as DRAMs) Problems with signal delays occur with logical devices. Thus, there has been a study of three-dimensional packaging techniques using a plurality of via plugs that involve forming via plugs of conductive material in the substrate and connecting the plurality of semiconductors with the vias in the most straightforward manner. Wafers, in turn, provide smaller and more efficient electronics.

A plurality of semiconductor wafers cannot be connected to each other only by providing via plugs in the substrate. It is therefore necessary to form electrode pads directly above the via plugs in the surface of the substrate or to form a rewiring layer for rearranging the positions of the electrode pads. It is also conceivable to form a lead-free solder bonding layer on the electrode pads.

1A to 2C depict a process for producing a conductive structure including a substrate and having a plurality of copper via plugs vertically penetrating the substrate inside the substrate, and having copper on a surface of the substrate Electrode gasket. First, as shown in FIG. 1A, the substrate W has a plurality of upwardly open via holes 12 (a groove as a via plug) and a seed layer 14 (conductive film) made of copper, such via holes. The 12 series is formed in the substrate 10 (for example, germanium) by a lithography/etching technique or the like, and the seed layer 14 is formed on the entire surface of the substrate W by sputtering or the like (including the It is on the inner surface of the through hole 12 and serves as a feeding layer for electroplating.

Copper plating is performed on the surface of the substrate W to deposit a first plating film 16 on the surface of the seed layer 14, while the through holes 12 are filled with the first plating film 16 as shown in FIG. 1B. Thereafter, the extra first plating film 16 remaining outside the through holes 12 is removed by chemical mechanical polishing (CMP) or the like, as shown in FIG. 1C.

Next, as shown in FIG. 2A, the resist layer pattern 18 is formed, for example, at a predetermined position on the surface of the substrate W by photoresist, so that the resist layer opening 20 conforms to the position and shape of the electrode pad. Thereafter, copper plating is performed on the surface of the substrate W to form a second plating film 22 in the resist opening 20 of the resist pattern 18, as shown in FIG. 2B. Thereafter, as shown in FIG. 2C, the excess seed layer 14 and the resist pattern 18 are removed from the surface (front surface) of the substrate W while the rear surface of the substrate W is ground and removed until the embedded The bottom of the first plating film 16 in the through hole 12 is exposed, and the conductive structure obtained thereby has a copper via plug 24 (by the first plating film 16 embedded in the through holes 12) And a plurality of electrode pads 26 (composed of the second plating film 22 formed in the resist layer opening 20 of the resist layer pattern 18).

3A through 3D depict a process for fabricating an insert or spacer having a plurality of copper via plugs therein for laminating a plurality of semiconductor substrates into multiple layers. Call these layers in a call. First, as shown in FIG. 3A, the substrate W has been pre-processed by depositing an insulating film 512 (for example, hafnium oxide) on the surface of the substrate 510 (for example, germanium), followed by formation by lithography/etching or the like. Multiple directions The upper through hole 514. For example, the diameters d of the vias 514 are between 1 micrometer (μm) and 100 micrometers, more specifically 10 micrometers to 20 micrometers, and the depth "h" is 70 micrometers to 150 micrometers. A barrier layer 516 (for example, tantalum nitride TaN) is formed on the surface of the substrate W, and then a (copper) seed layer 518 as a plating supply layer is formed on the surface of the barrier layer 516 by sputtering or the like. As shown in Figure 3B.

Thereafter, copper plating is performed on the surface of the substrate W to deposit a copper plating film 520 to cover the insulating film 512 while filling the via holes 514 with copper (plating film) as shown in FIG. 3C.

Thereafter, as shown in FIG. 3D, the excess copper film 520, the seed layer 518, and the barrier layer 516 on the insulating film 512 can be removed by CMP or the like while the back surface of the substrate W is ground and After removal, the bottom surface of the copper film is exposed in the through holes 514, and the inside of the thus obtained insert or spacer may have a plurality of vertically inserted through hole plugs 522.

In order to firmly fill the metal film into a deep via hole formed in the substrate having a high aspect ratio (typically having a diameter of 1 micrometer to 100 micrometers, more specifically, 10 micrometers to 20 micrometers, and a depth of 70 micrometers to 150 micrometers) In the micron), while avoiding the formation of defects such as voids in the embedded metal film, the Applicant has proposed a plating apparatus which can change the voltage applied between the substrate and the anode by the plating power source (see Japanese Patent Laid-Open Publication No.) No. 2005-97732); and another plating apparatus, stirring the plating solution when no voltage is applied between the substrate and the anode, and stopping stirring the plating solution when a voltage is applied between the substrate and the anode (see Japan) Patent early publication number 2006-152415).

As described above, the use of electroplating to form via plugs has been under investigation. In order to form the via plug by electroplating, a plurality of via holes (as recesses of the via plug) must be formed before plating, and a plating film (for example, copper) is filled in the through holes, and the like The pores have a diameter of from several micrometers to 100 micrometers and a depth of from tens of micrometers to hundreds of micrometers. However, it has taken a long time to fill a defect-free plating film into such a large through hole by a common plating method, and the low productivity causes a major obstacle to the use of electroplating to form a via plug. When the conductive structure is formed by the processes shown in FIGS. 1A to 2C, the process must pass through the following steps: plating → CMP → forming a resist layer → plating. Therefore, the production cost of the process is quite high. Therefore, the process can be regarded as forming an electrode pad, a rewiring layer, and a soldering layer by directly plating on the via plug. However, since the thickness of these layers is not less than a few micrometers, it will take more time to form the via plugs and the layers after electroplating under the same plating conditions.

Furthermore, it can be found that in the plating apparatus described in the above-cited patent documents, the excess plating film is formed in the surface area of the substrate in addition to being formed in the through hole, and since it is not used to reduce The resistance of the thickness of the plated film is so high that the amount of polishing and the production cost of the CMP process are relatively high, which may cause a major obstacle to the practical use of the plating devices. As particularly shown in FIG. 4, when the surface of the substrate so as to implement the plating film when a plurality of fill holes having a diameter D ₁ of the plating, the substrate surface outside the hole will be formed in the plating thickness T ₁ of the film. The thickness T ₁ will be greater than one-half of the diameter D ₁ of the holes (T ₁ > D ₁ /2). In order to reduce the burden of a later CMP process, it is desirable to selectively form a copper thin film by plating in a plurality of via holes to avoid being implemented in other regions.

It should be noted that when copper metal is filled into the through holes of the substrate by plating, if the plating growth rates of the inside and the outside of the through holes are the same, the thickness of the plating film must be equal to the radius of the through holes. If no countermeasure is taken, a plating film having the same thickness will be formed in the surface region of the substrate in addition to being formed in the through hole of the substrate. Although the growth of plating can be suppressed to some extent, for example, the use of additives in the plating solution, this is not sufficient.

In view of the foregoing, it is a first object of the present invention to provide a method of forming a conductive structure in a relatively short period of time by shortening the conventionally required longer plating time, which structure can be used for a plurality of via plugs. Three-dimensional packaging, because the long plating time is a major obstacle to the practical use of electroplating.

A second object of the present invention is to provide a plating apparatus and a plating method capable of selectively performing a process of forming a copper thin film by plating in a plurality of through holes, and further filling the through holes with the metal thin film And no defects are generated in the metal film, and the thickness of the excess metal film formed outside the through holes is minimized.

In order to achieve the first object, the present invention provides a method of forming a conductive structure, the method comprising: forming a conductive film on an entire surface of a substrate including a plurality of through holes, the integral surface comprising an inner surface of the plurality of through holes; Forming a resist layer pattern at a predetermined position on the conductive film; and performing the first electricity by using the conductive film as a supply layer under the first plating condition Plating, thereby filling the first plating film into the through holes; and performing second plating by using the conductive layer and the first plating film as a supply layer under the second plating condition The second plating film can be grown on the conductive film and the first plating film, and the conductive film and the first plating film are exposed in the resist opening of the resist pattern.

(Case 1) In a through hole formed in the surface of a substrate by etching or the like, a plating film such as copper as a metal material is filled by electroplating; (Case 2) a resistance formed on the surface of the substrate In the barrier opening of the layer pattern, a plated film such as copper is used as a metal material by electroplating. The two cases have considerable differences in the pattern configuration and the structure of the supply layer. For example, the through holes of Case 1 have a diameter of a few micrometers to tens of micrometers, a depth of 10 micrometers to 100 micrometers, and a depth to diameter ratio (a ratio of depth to diameter) greater than 1, and the layer of the case 2 The pattern has a thickness of several micrometers to several tens of micrometers and a size or width of the barrier layer opening of several micrometers to several tens of micrometers.

In the case 1, the through-hole ratio of the through holes is greater than 1, and the seed layer (supply layer) also appears on the side surface of the through holes. Therefore, unless the plated film preferentially grows from bottom to top from the bottom of the through holes, the plated film will preferentially grow in the openings of the through holes, resulting in the insertion of the through holes. Defects such as voids and cracks are formed in the metal film. Therefore, certain plating conditions must be optimized. The exemplary method uses a plating solution containing an additive capable of effectively suppressing the growth of the plating film at the through-holes, and further repeating the first plating operation for a specific period of time at a specific current value, followed by temporary reduction The current The values are recovered by waiting for copper ions that are consumed in the vias.

In Case 2, the supply layer is only present in the bottom of the barrier opening surrounded by the resist pattern. Therefore, when electroplating is performed, the plated film is grown from the bottom of the opening of the resist layer by through-mask plating, so that defects such as voids and cracks are formed in the plated film. Very low. However, the flow rate distribution of the plating solution in the resist pattern may cause disproportion of the pattern. This phenomenon may occur when the supply of copper ions cannot satisfy the plating rate, that is, when the plating is performed in a diffusion-controlled region. Therefore, in this case, the optimization of the flow rate of the plating solution by mechanical stirring and air agitation is more important than the composition of the plating solution and the current density.

When the plating film is filled into the through hole below the opening of the resist layer, the plating is more susceptible to being present than the plating for filling the plating film into the opening of the resist layer. The concentration distribution of the plating solution in the resist pattern is affected. Therefore, in addition to optimizing the addition of the plating solution and the current conditions as in Case 1, optimization of the flow conditions of the plating solution is also important.

As described above, in order to increase the integrity of the plating film and the efficiency of forming the film, it is necessary to optimize the plating conditions (such as the current, the composition of the plating solution, and the plating solution for the formation of the via or the barrier opening). Stirring conditions). The present invention is capable of filling a first plating film into a through hole by performing a first plating under a first plating condition, and then performing a second plating under the second plating condition so that the second plating film is grown on Resistive layer opening The resist layer pattern is formed at a predetermined position of the conductive film. After the resist pattern is formed in advance, the first plating film is filled into the through holes by performing the first plating, and the second plating is performed to grow the second plating film. In the resist opening of the resist pattern, it is possible to shorten the time required for plating and increase the productivity.

The height of the resist layer pattern is preferably from 5 micrometers to 10 micrometers.

In the case of forming a reconnection structure by using a second plating film formed in the opening of the resist layer in the surface of the substrate, the frequency of the electrical signal passing through the reconnection structure and the supplied current value are considered. Etc., the thickness of the second plated film must be at least about 5 microns. In the case of forming an electrode pad or post using a second plating film formed in the opening of the resist layer in the surface of the substrate, the thickness of the second plated film is preferably in view of the subsequent soldering step. It has a degree of tens of microns. When a solder material such as solder is to be deposited on the electrode pads by electroplating, the resist pattern requires an additional height of several tens of micrometers. Therefore, the height of the resist pattern is preferably not less than 5 μm but not more than 100 μm.

Preferably, the first plated film and the second plated film are composed of copper or a copper alloy.

The first plated film embedded in the through holes can be used as a via plug that connects the plurality of semiconductor wafers in the most direct manner for the purpose of producing a higher performance and smaller size electronic product. Therefore, it is desirable that the first plated film has high conductivity, that is, low resistance. Although gold, silver, and copper are all metals having such characteristics, only copper or copper-based alloys can be industrially subjected to bottom-up plating. In addition to cost From the standpoint of view, it is preferred to form the first plated film using copper or a copper alloy at least under the first plating condition.

As for the second plating film formed by performing the second plating under the second plating conditions, it is also desirable to use a highly conductive metal as the material of the second plating film. In addition, in order to consider the productivity, it is also desirable to form the first plating film and the second plating film in the same metal. Therefore, the second plated film is preferably also composed of copper or a copper alloy.

The average current value in the second plating condition is preferably higher than the average current value in the first plating condition.

From the standpoint of ensuring the area of the device, the total area of the plurality of via holes usually accounts for at most about 1% of the total area of the substrate, and never exceeds a few percentages of the total area of the substrate. On the other hand, the area of the plurality of rewiring structures or the plurality of electrode pads generally accounts for a few percentages to tens of percent of the total area of the substrate. Therefore, it is only necessary to supply a current sufficient to fill the first plating film into the through holes in the first plating under the first plating condition. On the other hand, the second plating performed to form the second plating film (possibly as a rewiring structure or an electrode pad) under the second plating condition is performed by the same current as the first plating, It will take a considerable amount of plating time. In view of this, the average current value in the second plating condition is preferably higher than the average current value in the first plating condition.

In a preferred aspect of the invention, the second plated film is grown to a half height of the top of the resist pattern, and then a third plating is performed under the third plating condition to cause the third plated film to grow on Above the second plated film.

Therefore, by forming a third plating film on the second plating film, the third plating film can serve as a bonding material between the plurality of wafers. By successively forming the third plating film (for forming an electrode pad or a rod) on the second plating film, a new resist layer pattern is not required, thereby reducing the cost. The third plating condition of the third plating, such as the composition of the plating solution used and the current density, is desirably optimized. Therefore, the third plating condition may be different from the first and second plating conditions.

Preferably, the metal of the third plating film is composed of a metal different from the first plating film and the second plating film.

The third plated film is used as a solder material, and the soldering property is preferred over the conductivity, so that a metal such as tin or a tin alloy is suitable, and the first plated film and the second plated are used. The metal of the film (such as copper) is different.

Preferably, the step of filling the first plating film into the through holes is terminated before the first plating film fills the through holes.

Therefore, before the first plating film fills the through holes, the first plating condition is changed to the second plating condition, that is, when the first plating film is embedded in each of the through holes. At the same time, the through holes still have a little concave surface. This can prevent the surface of the first plating film embedded in each of the through holes from exhibiting a convex shape. If the second plating is performed on the first plating film having the convex surface, the formed second plating film will have a portion corresponding to the center of the through holes more than the other portions. Thick thickness.

Preferably, before the first plating film completely fills the through holes, Plating is performed for a predetermined period of time at a second current value lower than the first current, the plating being performed at least once.

Therefore, by performing plating for a predetermined time at a second current value lower than the first current before the first plating film completely fills the through holes, it is possible to wait for consumption in the through holes. The copper ions are recovered.

Preferably, the plating solution is stirred with a stirring paddle while the plating is being performed, and the stirring pad is moved approximately parallel to the surface of the substrate.

As described above, when plating is performed in the opening of the resist layer surrounded by the resist pattern, the flow rate distribution of the plating solution in the resist pattern may cause an imbalance in the pattern structure of the plated film, and This results in a flat plating film that cannot be obtained. By causing the plating solution to flow upward into a device such as vertical plating, and using the stirring paddle during the plating process, the plating solution is reciprocate at a high speed in a direction approximately parallel to the surface of the substrate, It can help to enter the plating solution into the openings of the resist layer and reduce the imbalance in the pattern structure. In addition to simply reciprocating the agitating paddle, it is also possible to slowly move the center of reciprocation in one direction while reciprocating the agitating paddle.

Further, when the plating solution is stirred by a stirring blade to perform plating, the stirring blade may be rotated relative to the surface of the substrate.

In addition to the reciprocating motion of the agitating paddle, the paddle can also be rotated to assist in the plating solution into the openings of the resist layers. Therefore, the plating solution is flowed up into a jet flow-type plating apparatus, and the stirring paddle is rotated relative to the substrate surface during the plating process to agitate the plating solution. Can help to transfer the plating solution Into the resist layer openings and reduce the imbalance in the pattern organization. In view of the relatively slow relative movement of the plating solution near the center of rotation of the agitating paddle, the center of rotation of the paddle can be placed at a distance from the center of the substrate, and the paddle is rotated while being slow relative to the substrate surface. The center of rotation is moved so that the plating solution can flow uniformly over the entire substrate surface.

According to the method of the present invention for forming a conductive structure, a three-dimensionally packaged conductive structure having a plurality of via plugs can be plated with high in-plane uniformity at a reasonable cost and time. Film is formed to form. In addition, the method is capable of simultaneously forming a thin film of a solder material for soldering a plurality of semiconductor wafers.

In order to achieve the second object, the present invention provides a plating apparatus comprising: a plating tank for containing a plating solution; an anode immersed in the coating solution in the plating tank; for receiving the substrate and a substrate holder immersed in the plating solution and disposed at a position relative to the anode; a plating solution disposed between the anode and the substrate received by the substrate holder, and used to stir the plating solution in the plating tank a stirring member; a bubble supply member for supplying a bubble to a plating solution facing the surface to be plated of the substrate, the substrate holder receiving the substrate and dipping the substrate into the plating solution; and for using the substrate A plating power source that applies a voltage between the anode and the anode.

The inventors have conducted experiments and research on the copper plating method, and the proposed copper plating method can preferentially deposit copper in a plurality of holes on the surface of the semiconductor substrate, and can completely fill the holes with copper and does not occur. Defects and minimize copper deposited on the surface of the outer substrate of the holes. because Thus, it has been found that plating can be carried out by using a plating solution and by applying a voltage between the substrate and the anode while stirring the plating solution with a stirring paddle and supplying bubbles to the plating solution, wherein the plating solution In addition to copper ions, supporting electrolytes, and halogen ions, it also contains at least one of an organic sulfur compound, a polymer, and an organic nitrogen compound. By.

For example, it has been determined that plating can be performed by applying a voltage between an anode and a substrate having a plurality of holes (through holes having a diameter of about 1 micrometer to 100 micrometers) formed on a substrate, at the same time plating. The solution agitating member agitates the plating solution and supplies bubbles to the plating solution, so that plating is preferentially performed in the holes, so that plating is formed on the surface of the external substrate filled with the plated metal through holes. The thickness of the film (eg, copper) can be less than the radius of the through holes.

In a preferred aspect of the present invention, the bubble supply member is located between the plating solution stirring member and the substrate (the substrate holder receives the substrate and dipped the substrate into the plating solution), or is located at the substrate The plating solution is placed near the stirring member and disposed along the bottom of the plating tank.

In a preferred aspect of the invention, the bubble supply rate is from 0.1 liters per minute to 10 liters per minute.

The bubble supply rate is from 0.1 liter/minute to 10 liters/minute, preferably from 1 liter/minute to 5 liter/minute.

In a preferred aspect of the invention, the bubble supply member is formed by a hollow pipe having a plurality of hollow tubes in the lower half thereof. One or more columns of through-holes are arranged at a predetermined pitch.

For example, the diameter of the penetration holes is from 0.1 mm to 2.0 mm. The bubble supply member may be composed of a porous body.

The porous body may be a porous plastic or ceramic body. The structure of the bubble supply member can be simplified by using the porous body.

The present invention also provides a plating method, the method comprising: disposing a substrate and an anode opposite to each other in a plating solution in a plating tank; applying a voltage between the substrate and the anode; and supplying bubbles to the surface A plating solution of the surface of the substrate to be plated, and a plating solution between the substrate and the anode is stirred by a plating solution stirring member.

In a preferred aspect of the invention, the bubble is supplied from the bottom of the plating tank to the plating solution between the stirring solution of the plating solution and the substrate, or the plating near the stirring part of the plating solution. Solution.

For example, the bubble supply rate is from 0.1 liters/minute to 10 liters/minute.

According to the plating apparatus and the plating method of the present invention, when plating of a substrate having a plurality of holes (through holes having a diameter of about 1 μm to 100 μm) formed on a substrate is performed, a plating solution agitating member is used. Stirring the plating solution and supplying bubbles to the plating solution will preferentially effect plating in the through-holes filled with the plated metal such that a plating film formed on the surface of the substrate outside the through holes (for example The thickness of the copper can be smaller than the radius of the through holes.

10‧‧‧Base

12‧‧‧through hole

14‧‧‧ seed layer

16‧‧‧Plated film

18‧‧‧Resistance pattern

20‧‧‧resistive opening

22‧‧‧Plated film

24‧‧‧through hole plug

26‧‧‧electrode gasket

30‧‧‧resist pattern

30a‧‧‧resist pattern

32‧‧‧resistive opening

32a‧‧‧resistive opening

34a‧‧‧electrode gasket part

34b‧‧‧Connected section

36‧‧‧Plated film

36a‧‧‧coated film surface

38‧‧‧Plated film

40‧‧‧through hole plug

42‧‧‧electrode gasket

44‧‧‧Plated film

46‧‧‧welding layer

110‧‧‧ device framework

112‧‧‧ partition board

114‧‧‧Clean space

116‧‧‧ plating space

120‧‧‧bearing/unloaded埠

121‧‧‧Main control panel

122‧‧‧ aligner

124‧‧‧Cleaning/drying equipment

126‧‧‧Pre-processing equipment

127‧‧‧Pre-treatment tank

128‧‧‧Transfer robot

160‧‧‧Substrate support

160a‧‧‧Outwardly protruding part

160b‧‧‧Washing equipment

162‧‧‧Substrate Attachment/Separation Table

164‧‧‧Storage

166‧‧‧Activation equipment

168a‧‧‧cleaning equipment

168b‧‧‧Cleaning equipment

170‧‧‧ plating device

172‧‧‧Air drying equipment

174a‧‧‧Moving robot

174b‧‧‧Moving robot

176‧‧‧cross bar

178‧‧‧Ontology

180‧‧‧arm

182‧‧‧Substrate support part

183‧‧‧activation treatment tank

184a‧‧‧cleaning tank

184b‧‧‧cleaning tank

186‧‧‧ plating tank

186a‧‧‧ plating solution supply input hole

200‧‧‧Overflow trough

202‧‧‧ pump

204‧‧‧Circular pipeline

206‧‧‧Steady temperature unit

208‧‧‧Filter

210‧‧‧floor

212‧‧‧ plating solution distribution room

214‧‧‧Substrate processing room

216‧‧‧Protective panels

220‧‧‧Anode

222‧‧‧Anode holder

224‧‧‧Adjustment board

226‧‧‧ cylindrical part

228‧‧‧Rectangular flange section

232‧‧‧Agitating paddle

232a‧‧‧ strip

232b‧‧‧Band section

236‧‧‧ clamp

238‧‧‧Axis

240‧‧‧ shaft bracket

242‧‧‧Agitator paddle drive unit

244‧‧ ‧motor

246‧‧‧Control components

370‧‧‧ plating device

386‧‧‧ plating tank

386a‧‧‧ plating solution supply input hole

400‧‧‧Overflow trough

402‧‧‧ pump

404‧‧‧Circular pipeline

406‧‧‧temperature unit

408‧‧‧Filter

410‧‧‧floor

412‧‧‧Anode

414‧‧‧Anode holder

418‧‧‧Adjustment board

420‧‧‧ stirring paddle

422‧‧‧ bubble supply parts

424‧‧‧ hollow pipeline

424a‧‧‧through hole

430‧‧‧ plating power supply

510‧‧‧Base

512‧‧‧Insulation film

514‧‧‧through hole

516‧‧‧Barrier layer

518‧‧‧ seed layer

520‧‧‧ copper film

522‧‧‧through hole plug

D‧‧‧diameter

d ₀ ‧‧‧diameter

D ₂ ‧‧‧diameter

D1‧‧‧ diameter

H‧‧‧height

H‧‧‧ Height

L1, L2‧‧‧ length

P‧‧‧ spacing

Q‧‧‧ plating solution

T‧‧‧thickness

T1‧‧‧ thickness

T ₂ ‧‧‧ thickness

W‧‧‧Substrate

1A to 1C are diagrams illustrating a first-to-polish process of a conventional conductive structure process, the conductive structure having a plurality of vertically penetrating through-hole plugs therein; FIGS. 2A to 2C A diagram illustrating the post-grinding steps in a conventional process; Figures 3A through 3D illustrate a process for producing an insert or spacer having an interior having a vertical through structure a copper through hole; Fig. 4 is a view showing a state in which a plating film is filled in a through hole by a conventional plating method; and Fig. 5 is a plating device (electroplating device) used in the present invention a diagram of the overall layout of the plating facility; Figure 6 is a diagram of the transfer robot installed in the plating apparatus of Fig. 5; and Fig. 7 is a plating apparatus installed in the plating apparatus of Fig. 5. Sectional view of the apparatus; Figure 8 is a plan view of the agitating paddle used in the plating apparatus of Fig. 7; Fig. 9 is a sectional view taken along line AA of Fig. 8; Figs. 10A and 10B Corresponding to Fig. 9, showing a variation of the agitating paddle; Fig. 11 is a view showing a paddle driving of the plating device shown in Fig. 7. FIG mechanism and the plating tank; FIG. 12A through FIG. 12C illustrates an embodiment of the system of the present invention, the conductive structure is formed a first processing step to form a plated film; 13A and 13B are diagrams illustrating a subsequent process step according to the present invention; 14A is a plan view of Fig. 12B, and Fig. 14B is a plan view of different resist patterns; 15A to 15C The figure shows a graph of various different relationships between the current value and the time when the first plating is performed under the first plating condition; FIG. 16A illustrates the state in which the first plating film completely fills the through hole, and the 16B The figure illustrates the state before the first plating film fills the through hole; FIGS. 17A and 17B illustrate the formation of the conductive structure after forming the first plating film according to another embodiment of the present invention. Figure 18 is a cross-sectional view of a plating apparatus according to an embodiment of the present invention; Figure 19 is a bottom view of a bubble supply part of the plating apparatus of Figure 18; Figure 20 is an 18th drawing A cross-sectional view of the bubble supply member of the plating apparatus; a sectional view of the other bubble supply member in the 21st; a sectional view of the other air supply member in the 22nd; and a description of the plating in the 23rd a pattern of parameters of the film; and a description of Figure 24 In Example 1 has been filled by electroplating the through-hole plated film state.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings. Figure 5 is a plating apparatus for plating a conductive structure of the present invention (electroplating) The overall layout of the device). The plating apparatus is designed to automatically perform all of the plating processes in a sequential manner, including pre-treatment, plating, and subsequent processing of the substrate. The interior of the device frame 110 is divided into a plating space 116 and a cleaning space 114 by means of a partition plate 112 to which an armored panel is attached. The space 116 is used to perform a plating process of the substrate and a substrate to which the plating solution is attached, and the cleaning space 114 is used for performing other processes, that is, a process not directly related to the plating solution. Two substrate holders 160 (shown in FIG. 6) are arranged in parallel, and a substrate attachment/detachment stage 162 for attaching the substrate to and separating the substrate from each of the substrate holders 160 Provided as a substrate transporting member, it is located on a partition portion partitioned by the partitioning plate 112. The partitioning plate 112 separates the plating space 116 from the cleaning space 114. A carrier/unloaded cassette 120 is attached to the cleaning space 114, and a substrate cassette storing a plurality of substrates is placed on the carrier/unloaded cassette 120. In addition, a main control panel 121 (console panel) is mounted on the device frame 110.

In the cleaning space 114, an aligner 122 for aligning an orientation flat or a notch of a substrate in a predetermined direction, and two cleaning/drying apparatuses 124 are disposed. The substrate to be plated is cleaned and the substrate is rotated at a high speed to spin-dry the substrate. In addition, a first transfer robot 128 is disposed substantially at the center of the process devices (ie, the aligner 122 and the cleaning/drying devices 124), and further, at the process devices 122 and 124, The substrate attachment/detachment stage 162 and the substrate trays attached to the carrier/unloaded cassette 120 are mobilized and transported between the substrates.

The aligner 122 disposed in the cleaning space 114 and the cleaning/drying apparatus 124 are designed to receive and process the substrate in a horizontal and front face up state. The transfer robot 128 is designed to mobilize and transport the substrate in a horizontal and face up state.

In the plating space 116, a stocker 164 for storing or temporarily storing the substrate holders is sequentially arranged by the partitioning plate 112, and pre-cleaning is performed, for example, by using pure water to clean the surface of the substrate. Rinsing pretreatment and pretreatment equipment 126 for wetting the surface of the substrate with pure water to enhance the hydrophilicity of the surface of the substrate, using a mineral acid solution (such as sulfuric acid or hydrochloric acid) or an organic acid solution (such as citric acid or oxalic acid) An activation treatment device 166 for etching an oxide film having a high electrical resistance on a seed layer formed on the surface of the substrate to remove the oxide film, and a first cleaning for cleaning the surface of the substrate with pure water The device 168a, a plating device (copper plating device) 170 for performing plating (copper plating), a second cleaning device 168b, and an air drying device 172 for dehydrating the plated substrate. Two second transfer robots 174a and 174b are disposed beside these devices for movement along the crossbar 176. One of the second transfer robots 174a mobilizes the substrate holders 160 between the substrate attachment/detachment stages 162 and the reservoir 164. Another second transfer robot 174b is in the reservoir 164, the pre-processing device 126, the activation processing device 166, the first cleaning device 168a, and the plating device. The substrate holder 160 is moved between the second cleaning device 168b and the air drying device 172.

As shown in Fig. 6, each of the second transfer robots 174a and 174b has a body 178 extending in a vertical direction and an arm 180 movable vertically along the body 178 and rotating about its axis. The arm 180 has two parallel-mounted substrate holder receiving portions 182 for supporting the substrate holders 160 separately. The substrate holder 160 is designed to receive the substrate in a state where the front surface of the substrate W is exposed but the peripheral portion is sealed, and the substrate W can be attached to the substrate holder 160 and the two can be separated.

The reservoir 164, the pretreatment device 126, the activation processing device 166, the cleaning devices 168a, 168b, the plating device 170, and the air drying device are designed to protrude outwardly from both ends of each substrate holder 160. The portion 160a is engaged, and the outwardly protruding portion 160a is for supporting the substrate holders 160 to be suspended in the vertical direction. The pre-treatment device 129 has two pre-treatment tanks 127 for receiving pure water. As shown in FIG. 6, the arm 180 of the second transfer robot 174b for receiving the substrate holder 160 carrying the substrate W in a vertical state is lowered to be engaged with the upper ends of the pre-treatment grooves 127, and The substrate holders 160 are supported by suspension. Therefore, the pre-processing apparatus 126 is designed to immerse the substrate holders 160 together with the substrates W in pure water in the pre-treatment tanks 127 to perform pre-processing. The activation treatment device 166 has two activation treatment tanks 183 for receiving chemical liquids. As shown in FIG. 6, the second transfer robot 174b is configured to receive the vertical load carriers. The arms 180 of the substrate holder 160 of the board W are lowered to engage the upper ends of the activation processing tanks 183 to support the substrate holders 160 in a suspended manner. Therefore, the activation processing apparatus 166 is designed to immerse the substrate holders 160 together with the substrates W in the chemical liquid in the activation processing tanks 183 to perform an activation process.

Similarly, the cleaning devices 168a and 168b respectively have two cleaning tanks 184a for receiving pure water and two cleaning tanks 184b for receiving pure water, and the plating device 170 has a plurality of plating tanks 186 for receiving the plating solution. . The cleaning apparatus 168a, 168b and the plating apparatus 170 are designed to immerse the substrate holders 160 together with the substrates W in pure water in the cleaning tanks 184a and 184b or to be plated in the plating tanks 186. The coating is applied to carry out a cleaning treatment or to perform plating in the same manner as described above. The arm 180 of the second transfer robot 174b for receiving the substrate holder 160 that carries the substrate W in a vertical state is lowered, and the air or inert gas is injected toward the substrate W placed on the substrate holder 160 (inert The gas is used to blow off the liquid adhering to the substrate holder 160 and the substrate W and remove the moisture of the substrate W. Therefore, the air drying device 172 is designed to perform an air drying process.

As shown in FIG. 7, each of the plating tanks 186 installed in the plating apparatus 170 is designed to receive a predetermined amount of the plating solution Q. The receiving state of the substrates W is such that the front surface (to be plated surface) is exposed and the peripheral portion is waterproof-sealed by the substrate holder 160, and is immersed in the plating solution Q in the vertical direction. In this embodiment, the plating solution used as the plating solution Q is in addition to copper ions, supplemental electrolytes, and halogen ions. Also included is at least one of an organic sulfide, a polymer, and an organic nitride. Preferably, sulfuric acid is used as a supplementary electrolyte, and chlorine ion is used as a halogen ion.

The overflow tank 200 is installed around the upper end of the plating tank 186 for receiving the plating solution Q overflowing to the edge of the plating tank 186. One end of a circulation piping 204 equipped with a pump 202 is connected to the bottom of the overflow tank 200, and the other end of the circulation duct 204 is connected to the bottom of the plating tank 186. The plating solution is supplied to the input hole 186a. The plating solution Q in the overflow tank 200 is returned to the plating tank 186 by priming the pump 202. The tempering unit 206 located at the downstream of the pump 202 and the filter 208 are inserted into the circulation duct 204 for controlling the temperature of the plating solution Q, and the filter 208 is It is used to filter out foreign matter in the plating solution.

A bottom plate 210 having a large number of plating solution passage holes is attached to the bottom of the plating tank 186. Therefore, the inside of the plating tank 186 is divided into an upper substrate processing chamber 214 and a lower plating solution distribution chamber by the bottom plate 210. In addition, a vertically downwardly extending shield 216 is attached to the underside surface of the bottom plate 210.

According to the plating apparatus 170 of this embodiment, the plating solution Q is introduced into the plating solution distribution chamber 212 of the plating tank 186 by the pump 202, and flows through the plating solution passage hole provided in the bottom plate 210. Substrate process The processing chamber 214 flows vertically in a direction parallel to the surface of the substrate W (which is received by the substrate holder 160), and then flows into the overflow tank 200.

The shape of the anode 220 is a circle corresponding to the shape of the substrate W. The anode 220 is received by the anode holder 222 and vertically mounted in the plating tank 186. When the plating solution Q is injected into the plating tank 186, the anode 220 is immersed in the plating solution Q, and faces the substrate which is received by the substrate holder 160 and disposed at a predetermined position in the plating tank 186. W. Further, in the plating tank 186, an adjustment plate 224 for adjusting an electric potential distribution in the plating tank 186 is disposed at a predetermined position of the plating tank 186 between the anode 220 and the substrate W. In this embodiment, the adjustment plate 224 is composed of a cylindrical portion 226 and a rectangular flange portion 228, and is made of a dielectric material of polyvinyl chloride. The cylindrical portion 226 has an opening size and an axial length sufficient to limit electric field expansion. The lower end of the flange portion 228 of the adjustment plate 224 can reach the bottom of the bottom plate 210.

A vertically extending stirring paddle 232 is disposed between the adjusting plate 224 and the substrate W (which is intended to be disposed at a predetermined position in the plating groove 186). The stirring paddle 232 reciprocates back and forth parallel to the surface of the substrate W to stir. The plating solution Q between the substrate W and the adjustment plate 224. By stirring the plating solution Q by the stirring paddle 232, a sufficient amount of copper ions can be uniformly supplied to the surface of the substrate W. In order to obtain sufficient agitation efficiency, the distance between the paddle 232 and the surface of the substrate W is preferably less than 30 mm, and more preferably less than 15 mm, while the paddle 232 cannot come into contact with the substrate holder 160.

As shown in Figs. 8 and 9, the agitating paddle 232 is composed of a rectangular plate-like member having a uniform thickness t (3 mm to 5 mm) and has a plurality of parallel plates. A parallel strip defining a vertically extending strip-like portion 232b (strip-like). For example, the agitating paddle 232 is formed of a titanium metal having a Teflon coating. The vertical length L _{1 of the} paddle 232 and the vertical length L ₂ of the strips 232a are sufficiently larger than the vertical dimension of the substrate W. Further, the agitating paddle 232 is designed such that the sum of the lateral length H and the reciprocating distance (stroke, St) is sufficiently larger than the lateral size of the substrate W.

The width and number of the strips 232a are preferably set such that each strip portion 232b is as narrow as possible, but still provides the strips 232a with the required stiffness and the strip between the strips 232a The portion 232b is capable of effectively agitating the plating solution, and further the plating solution can effectively pass through the strips 232a.

In this embodiment, as shown in Fig. 9, the strips 232a are formed vertically such that each of the strip portions 232b has a rectangular cross section. As shown in Fig. 10A, each of the strip portions 232b may be chamfered at four corners of its cross section, or as shown in Fig. 10B, each strip portion 232b may have a certain The inclination of the angles has a cross-sectional shape of a parallelogram.

As shown in Fig. 11, the agitating paddle 232 is secured to a horizontally extending shaft 238 by a plurality of clamps 236 fixed to the upper end of the agitating paddle 232. The shaft 238 is supported by a plurality of shaft brackets 240 and can Sliding horizontally. The end of the shaft 238 is coupled to the agitating paddle driving member 242 for reciprocating the agitating paddle 232 linearly and horizontally. The paddle drive member 242 converts the rotation of the motor 244 into a linear reciprocating movement of the shaft 238 by a crank mechanism (not shown).

In this embodiment, a control member 246 is provided that controls the rotational speed of the agitating paddle 232 by controlling the rotational speed of the motor 244 of the agitating paddle driving member 242. In addition to the agitating paddle driving member 242 using the crank mechanism, a paddle driving member that converts the rotation of the servo motor into a linear reciprocating motion of the shaft by a ball screw, or a shaft by a linear motor may be used. Agitating paddle drive unit that reciprocates linearly. In order to obtain sufficient agitation efficiency, the speed of movement of the agitating paddle 232 is preferably greater than 0.2 meters per second, and more preferably greater than 0.5 meters per second. From the standpoint of device design, the speed of movement of the paddle 232 cannot be greater than 2.0 meters per second.

The plating apparatus 170 is provided with a plating power source 250. During the plating process, the anode of the plating power source 250 is connected to the anode 220 through a wire, and the cathode is connected to the substrate W through a wire. In this embodiment, the power source of the plating power source 250 has a supply current range that covers at least ten times the current increase amount.

During the operation of the plating apparatus 170, first, a plating solution Q having a predetermined amount and having a predetermined composition is injected into the plating tank 186 as described above, and agitation is performed. Next, the substrate holder 160 that receives the substrate W is lowered to arrange the substrate W at a predetermined position in the plating tank 186 and immersed in the plating. Solution Q. The anode 220 is connected to the anode of the plating power source 250, and the substrate W is connected to the cathode of the plating power source 250. In this state, the stirring paddle 232 can be reciprocated parallel to the surface of the substrate W as needed, thereby agitating the plating solution Q between the adjusting plate 224 and the substrate W. Therefore, a plating film is deposited on the surface of the substrate W. The pump 202 of the circulation pipe 204 may be driven to perform circulation of the plating solution Q while cooling the plating solution Q to be maintained at a predetermined temperature. After a predetermined time elapses, application of a voltage between the anode 202 and the substrate W is stopped, and the reciprocating movement of the stirring paddle 232 is terminated to end the plating.

A method of forming a conductive structure according to an embodiment of the present invention will now be described.

12A to 13B illustrate a method for fabricating a conductive structure including a substrate, a plurality of via plugs positioned inside the substrate and vertically penetrating the substrate, and a copper electrode pad in the surface of the substrate sheet. First, as shown in FIG. 12A, a substrate W having a plurality of upwardly opening via holes 12 is formed, which are formed in the substrate 10 (for example, germanium) by lithography/etching or the like. The copper seed layer 14 (conductive film) is formed on the entire surface of the substrate W (including the inner surface of the through holes 12) by sputtering or the like, and the copper seed layer 14 serves as a supply layer for electroplating.

Next, as shown in FIG. 12B, the resist pattern 30 is formed at a predetermined position on the surface of the substrate W by, for example, photoresist. In this embodiment, a plurality of copper electrode pads 42 (as shown in FIG. 13B) will be formed on the surface of the substrate W. Therefore, as shown in FIG. 14A, each resist layer of the resist layer pattern 30 The openings 32 are located just above each of the through holes 12, and the resist opening 32 is rectangular or circular to conform to the shape of the electrode pad, and the electrode pad is larger than the through hole 12.

If a rewiring structure for rearranging the positions of the electrode pads is formed on the surface of the substrate W, the resist opening 32a of the resist pattern 30a is composed of a plurality of electrode pads placed directly above the through holes 12. The sheet portion 34a is formed, and the wiring portion 34b extends from the electrode pad portions 34a and conforms to the shape of the plurality of reconnection structures as shown in Fig. 14B.

The height h of the resist layer pattern 30 is preferably from 5 micrometers to 100 micrometers. As described below, a second plated film 38 is formed in the resist layer opening 32 for use as an electrode pad or rewired structure. If there is a reconnection structure, the reconnection structure requires at least a thickness of about 5 microns in view of the frequency of the electrical signals passing through the reconnection structures, the supplied current, and the like. If there are a plurality of electrode pads or rods, the electrode pads or rods preferably have a thickness of several tens of micrometers in consideration of the subsequent welding conditions. As described below, when it is intended to form a third plating film 44 (for example, solder) as a soldering layer on the second plating film, the resist layer pattern 30 requires an additional height of several tens of micrometers. Therefore, the resist pattern 30 having a height of not less than 5 μm and not more than 100 μm can be used to form the second plating film 38 and the third plating film 44 having a sufficient thickness in the resist layer openings 32.

Next, as shown in FIG. 12C, the seed layer 14 is used as a supply layer, and the first plating is performed by a predetermined plating current between the seed layer 14 and the anode 220 under the first plating condition. Further, the first plating film 36 is filled in the through holes 12. The first plated film can also be formed On the surface of the seed layer 14, the seed layer 14 is located in the resist layer opening 32 and outside of the through holes 12.

In this case, the depth-to-diameter ratio of the through holes 12 is not less than 1 and the seed layer 14 as the supply layer is also present on the side surfaces of the through holes 12. Therefore, unless the first plating film 36 is preferentially grown from bottom to top from the bottom of the through holes, the plated film will preferentially grow on the holes of the through holes 12, resulting in the insertion of the through holes 12 Defects such as voids and cracks are formed in the first plating film 36. Therefore, it is necessary to optimize the first plating conditions for the first plating. The exemplary method uses a plating solution containing an additive capable of effectively suppressing growth of the plating film at the through-holes, and further, repeating the first performing plating operation for a specific period of time under a specific current value And then temporarily lowering the current value to wait for the copper ions consumed in the through holes 12 to recover.

The current applied between the seed layer 14 and the anode 220 may be a fixed current as shown in FIG. 15A, a stepped current in which the current is stepwise increased as shown in FIG. 15B, or repeated as shown in FIG. 15C. Supply and stop the pulse current of the supply current.

In order to enhance the bottom-up growth of the plating, the average current density in the first plating is preferably 0.1 mA/cm 2 to 10 mA/cm 2 , more preferably 0.1 mA/cm 2 . 5 mA / cm ^ 2 . When the average current density in the first plating is less than 0.1 mA/cm 2 , it takes a long time to fill the first plating film into the through hole 12, resulting in a decrease in productivity.

After terminating the filling of the first plating film 36 into the through hole 12, The second plating is performed by the seed layer 14 and the first plating film 36 as a supply layer under the second plating conditions. Preferably, the first plating film 36 is terminated before the first plating film 36 fills the through hole 12.

In particular, the first plating system in which the first plating film 36 is filled in the through holes 12 is carried out in a bottom-up manner as described above. As shown in FIG. 16A, if the through holes 12 fill the first plating film 36 into the through holes 12 by plating from bottom to top, the first plating in each of the through holes 12 The surface 36a of the film 36 will generally have a convex shape with a central portion convex. This is because the additive promotes the growth of the plating film from the center of each of the through holes 12. This effect continues for a specific period of time even during the second plating process performed under the second plating condition after the termination of the first plating. Therefore, if the through holes 12 are completely filled by the first plating film 36, the second plating film 38 is formed by performing the second plating under the second plating conditions as follows. The second plating film formed will have a thicker thickness than the other portions at its portion corresponding to the center of the through holes. The local thickness variation of the plated film will cause later soldering problems and should therefore be avoided.

Therefore, it is preferable that the first plating condition has become the second plating condition before the through holes 12 are completely filled by the plating film 36, that is, when the first plating film 36 is embedded in each In a through hole 12, the through holes 12 still have a somewhat concave surface. This can prevent the surface of the first plating film 36 embedded in each of the through holes 12 from being convex.

As described below, the second plating film 38 formed by performing the second plating under the second plating conditions is used to form a plurality of electrode pads or rewiring lines. And forming a plated film having a uniform thickness on the surface of the unit substrate under such conditions. Therefore, even when the surface 36a of the first plating film 36 in each of the through holes 12 generally has a slightly concave surface, the second plating film 38 having a flat surface can be formed in the resistance layer opening 32. However, provided that the depth-to-diameter ratio of the resist layer openings 32 is less than 2, and preferably less than one.

In the second electroplating performed under the second plating condition, the seed layer 14 and the first plating film 36 are used as a supply layer, and the second plating film 38 can be grown on the seed layer 14 and the first On the plating film 36, both the seed layer 14 and the first plating film 36 are exposed to the resist opening 32 of the resist pattern as shown in FIG. 13A.

In the second plating, the seed layer 14 as the supply layer and the first plating film 36 exist only at the bottom of the resist opening 32 surrounded by the resist pattern. Therefore, the second plating film 38 is grown from the bottom of the resist layer openings 32 by a through-masking method after the plating is performed. Therefore, the possibility of forming defects such as voids and cracks in the second plating film 38 is low. However, the flow rate distribution of the plating solution in the resist pattern 30 may cause the pattern composition of the second plating film 38 to be unbalanced. This phenomenon may occur when the supply of copper ions cannot satisfy the plating rate, that is, when plating is performed in the diffusion control region. Therefore, the flow rate optimization of the plating solution by mechanical stirring and air agitation in this case is more important than the composition of the plating solution and the density of the current.

The term "air stirring" as used herein refers to moving the paddles in parallel during the plating process to agitate the plating solution and simultaneously supply the bubbles. (eg, air or nitrogen) to the plating solution such that the supplied bubbles flow along the entire surface of the substrate.

Therefore, in this embodiment, the plating solution flows upward into the plating tank 186, and the plating solution is reciprocally agitated at a high speed in a direction approximately parallel to the substrate W during the plating process. . This can increase the supply of plating solution in the resist layer openings 32 and can reduce the imbalance in the pattern structure. In addition to simply agitating the agitating paddle, the reciprocating center can be slowly moved in one direction while reciprocating the agitating paddle.

In this embodiment, although the reciprocating agitating paddle 232 is used to agitate the plating solution during the plating process, a rotary agitating paddle may also be utilized. By moving the plating solution upward into a plating apparatus such as a spray type, and rotating the stirring paddle relative to the surface of the substrate during the plating process to agitate the plating solution, the opening of the resist layer can be enhanced. The supply of plating solution reduces the imbalance in the pattern organization. In view of the fact that the plating solution near the center of rotation of the stirring blade moves relatively slowly, the center of rotation of the stirring blade can be placed at a distance from the center of the substrate, and the rotating paddle is rotated while being rotated relative to the The surface of the substrate slowly moves the center of rotation such that the plating solution can flow uniformly over the surface of the unitary substrate.

According to the embodiment, in order to increase the integrity of the first plating film 36 and the second plating film 38 and the efficiency of film formation, plating conditions (such as current, composition of the plating solution, and stirring of the plating solution) The condition can be optimized for the individual configurations of the via 12 or the resist opening 32, and the first plating film 36 is filled by performing the first plating under the first plating conditions. Into the through holes 12, second plating is then performed under the second plating conditions to cause the second plating film 38 to be grown in the resist opening 32 of the resist pattern 30, wherein the resist pattern is formed on the conductive The predetermined position on the film. In addition, after the resist pattern is formed in advance, the first plating film 36 is filled into the through holes 12 and the second plating is performed to perform the second plating film. The growth of 38 in the resist opening 32 of the resist pattern 30 may shorten the time required for plating and increase the throughput.

From the standpoint of ensuring the area of the device, the total area of the through holes 12 is usually at most about 1% of the total area of the substrate, and never exceeds a few percentages of the total area of the substrate. On the other hand, the area of the plurality of rewiring structures or the plurality of electrode pads is usually from a few percent to tens of percent of the total area of the substrate. Therefore, it is only necessary to supply the current required to fill the first plating film 36 into the through holes 12 in the first plating under the first plating condition. On the other hand, if the second plating performed to form the second plating film 38 (becoming a rewiring structure or an electrode pad) under the second plating condition is performed by the same current as the first plating It will take a long time to plate. In view of this, the average current value in the second plating condition is preferably higher than the average current value in the first plating condition.

It is generally desirable to increase this current value as the plated area increases. Therefore, it is desirable that the average current value in the second plating condition is at least twice the current value of the first plating condition, and is usually ten times. Therefore, it is desirable that when the first plating and the second plating are successively performed in the same plating tank, the plating power source of the plating tank has at least a supply range covering a ten-fold current increase amount. As above The stepped current or pulse current can be utilized in the first plating performed under the first plating conditions. Moreover, in this case, the average current value in the second plating is preferably higher than the average current value in the first plating.

The first plating film 36 embedded in the through holes 12 can be used as a via plug which connects the plurality of halves in the most direct manner to achieve a higher production efficiency and smaller size electronic product. The purpose. Therefore, it is desirable that the first plated film has high conductivity, that is, low resistance. Although gold, silver, and copper all have such characteristics, only copper or copper-based alloy plating can be industrially performed from the bottom to the top. Further, from the viewpoint of cost, it is preferable to use at least copper or a copper alloy as the first plating film 36 formed under the first plating conditions.

Regarding the second plating film 38 formed by performing the second plating under the second plating conditions, it is also desirable to use a highly conductive metal as the second plating film. Further, in view of the problem of productivity, it is desirable to successively form the first plating film 36 and the second plating film 38 which are composed of the same metal. Therefore, the second plated film 38 is preferably also composed of copper or a copper alloy.

Then, as shown in FIG. 13B, the additional seed layer 14 and the resistive pattern 30 are removed from the surface of the substrate W while the rear surface of the substrate W is ground and removed until embedded in the through holes 12. The bottom of the first plating film 36 is exposed, thereby obtaining a copper via plug 40 (composed of the first plating film 36 embedded in the through holes 12), a plurality of electrode pads 42 and An electrically conductive structure of the solder layer 46 of the solder material, the electrode pads 42 being formed by the resist opening 32 formed in the resist pattern 30 The second plating film 38 is composed of a third plating film 44 formed on the second plating film 38. The thickness of the solder layer 46 is, for example, tens of microns.

17A and 17B are diagrams illustrating a process step for forming a conductive structure in accordance with another embodiment of the present invention. As in the previous embodiment, as shown in FIG. 12C, the first plating film 36 is filled into the through holes 12 by performing the first plating under the first plating conditions. Thereafter, as shown in FIG. 17A, the second plating is performed under the second plating condition so that the second plating film 38 can be grown to a half height of the top of the resist pattern 30, and then implemented under the third plating condition. The third plating enables the third plating film 44 to be grown on the second plating film 38.

The third plating film 44 is used as a solder layer 46 (welding material) between a plurality of wafers for soldering. The subsequent formation of the third plating film 44 on the second plating film 38 (for forming an electrode pad or a rod) can eliminate the need for a new resist pattern, thereby eliminating the increase in cost. It is desirable to be able to optimize the third plating conditions for the third plating, such as the composition of the plating solution used and the current density. Therefore, the third plating condition may be different from the first and second plating conditions.

As described above, the third plating film 44 is used as a solder material, and the soldering characteristics thereof are preferred over the conductivity. Therefore, it is preferable to use a metal such as tin or a tin alloy, unlike a metal (e.g., copper) used for the first plating film 36 and the second plating film 38.

Next, as shown in FIG. 17B, the additional seed layer 14 and the resistive pattern 30 are removed from the surface of the substrate W while being ground and removed. The rear surface of the substrate W is exposed until the bottom of the first plating film 36 embedded in the through holes 12 is obtained, thereby obtaining a copper via plug 40 (the first one embedded in the through holes 12) The electroconductive structure of the plating film 36 and the plurality of electrode pads 42 are composed of a second plating film 38 formed in the resist opening 32 of the resist pattern 30. The thickness of the electrode pads 42 is, for example, several tens of micrometers.

Hereinafter, a process of forming the first plating film 36 of FIG. 12C and the second plating film 38 of FIG. 13A by the plating apparatus (copper plating apparatus) of FIG. 5 will be described.

First, the substrate W has a plurality of through holes (recessed as via holes) 12 formed in the upper substrate 10, and a seed layer (conductive) formed as an electroplating supply layer on the entire surface of the substrate W. Film) 14. The substrate W is placed in the substrate tray with its front surface (the surface to be plated) facing upward, and the substrate tray is placed on the carrier/unloaded crucible 120.

One of the substrates W is taken out by the first transfer robot 128 from the substrate tray attached to the load/unload cassette 120, and placed on the aligner 122 to align the orientation plane or the substrate in a predetermined direction. mark. On the other hand, the two substrate holders 160 vertically stored in the reservoir 164 are taken out and rotated by 90 degrees by the second transfer robot 174a, so that the substrate holder 160 is in a horizontal state, and then placed in parallel. The substrate is attached/detached on the stage 162.

The substrate W aligned with the orientation plane or the self-substrate in a predetermined direction is mobilized and is received in a state in which the peripheral portions of the substrates are sealed and It is placed in the substrate holder 160 on the substrate attachment/detachment stage 162. The second transfer robot 174a simultaneously holds, lifts, and then transfers the two substrate holders 160 that receive the substrates W to the reservoir 164. The substrate holders 160 are rotated 90 degrees into a vertical state and are lowered such that the two substrate holders 160 are received (temporarily) in the reservoir 164 in a suspended manner. The above operations are repeatedly performed in a continuous manner such that a plurality of substrates are successively received by the substrate holders 160 stored in the reservoir 164, and successively suspended (storage) in the reservoir 164 in a suspended manner. The predetermined location in .

On the other hand, the second transfer robot 174b simultaneously holds, lifts, and then mobilizes the two substrate holders 160 that receive the substrates W and temporarily stored in the reservoir 164, and then mobilizes to the pre-processing device 127. Each of the substrates is immersed in a pretreatment liquid (such as pure water received by the pretreatment tank 127) to carry out pretreatment (cleaning pretreatment). The dissolved oxygen concentration of the pure water used as the pretreatment liquid is preferably controlled to be not less than 2 mg/liter by a vacuum vaccum deaerator or introduction of an inactive gas. Next, the substrate holder 160 carrying the substrates W is mobilized to the activation processing apparatus 166 in the same manner as described above. Each substrate is immersed in a mineral acid solution (such as sulfuric acid or hydrochloric acid) or an organic acid solution (such as citric acid or oxalic acid) received by the activation treatment tank 183 to further form an oxide having high electrical resistance on the surface of the seed layer. The film is etched to expose a clean metal surface. The dissolved oxygen concentration of the acid solution used in this activation treatment can be controlled as in the case of pretreatment of pure water used. The substrate holder 160 carrying the substrates is mobilized to the first cleaning in the same manner as described above The device 168a cleans the surfaces of the substrates with pure water received by the cleaning tank 184a.

After cleaning the surfaces of the substrates, the substrate holders 160 carrying the substrates are transferred to the plating apparatus 170. In the plating apparatus 170, each of the substrates is suspended and supported on the plating tank 186. And it is immersed in the plating solution Q in the plating tank 186 to perform plating of the surface of the substrate W.

Before starting the first plating under the first plating condition, the substrate W received by each of the substrate holders 160 is immersed in the plating solution Q, but no current is applied for a predetermined time, so that the plating solution is replaced. Water remaining in the through holes 12 and previously used for cleaning. The predetermined time is preferably less than one minute. If the predetermined time is too long, the seed layer will dissolve in the plating solution.

As described above, in FIG. 12C, the first plating of the substrate is performed under the first plating conditions for filling the first plating film 36 into the through holes 12. The first plating condition is plated from bottom to top such that the plated film can preferentially grow from the bottom of the through holes 12. As shown in FIG. 13A, after the first plating film 36 is filled in the through holes 12, the first plating condition is switched to the second plating condition, and is performed under the second plating condition. The second plating is performed on the conductive film 14 and the first plating film 36, and both the conductive film 14 and the first plating film 36 are exposed to the resist layer. The pattern 30 is in the resistive opening 32. For example, the average current value used in the second plating condition is at least twice the average current value used in the first plating condition (usually at least ten) The paddle 232 is moved in an optimized manner to agitate the plating solution Q.

A plurality of plating solutions having different compositions may also be utilized to perform the first plating under the first plating conditions and the second plating under the second plating conditions.

After the second plating is completed, the second transfer robot 174b re-accepts the substrate holder 160 of the carrier substrate and pulls up from the plating grooves 186.

Thereafter, the substrate holders 160 are mobilized to the second cleaning device 168b in the same manner as described above. The substrate holders 160 are immersed in the pure water in the cleaning tanks 184b to clean the surfaces of the substrates with pure water. The substrate holder 160 carrying the substrates is then mobilized to the air drying device 172 in the same manner as described above. In the air drying device 172, an inert gas or air is sprayed toward the substrates to blow off the plating solution and water droplets attached to the substrate holders 160. Thereafter, the substrate holder 160 carrying the substrates is returned to a predetermined position in the reservoir 164 in the same manner as described above, and is received in a suspended manner.

The second transfer robot 174b repeatedly performs the above operations in succession such that the substrate holders 160 carrying the substrates to be plated are successively returned to a predetermined position 164 in the reservoir and are received in a suspended manner. On the other hand, the two substrate robots 160 carrying the substrates to be plated are simultaneously supported by the second transfer robot 174a in the same manner as described above, and placed on the substrate attachment/detachment stages 162.

The first transfer robot 128 disposed in the clean space 114 will The substrate is removed from one of the substrate holders 160 on the substrate attachment/detachment stage 162 and the substrate is mobilized to one of the cleaning/drying devices 124. In the cleaning/drying apparatus 124, the substrate is placed in a horizontal position facing upward, after the substrate is cleaned with pure water, and then the substrate is spin-dried by high-speed rotation. Thereafter, the substrate is returned to the substrate tray attached to the carrier/unloading cassette 120 by the first transfer robot 128, thereby completing a series of processing steps to obtain the substrate W as shown in FIG. 13A. . The substrate W has a first plating film 36 embedded in the through holes 12 for forming a plurality of via plugs 40, and is formed in the resist layer opening 32 of the resist layer pattern 30 to form a plurality of electrode pads. A second plated film 38 of 42.

As shown in FIGS. 17A and 17B, when the third plating film 44 is to be formed on the second plating film 38 by performing the third plating under the third plating condition, in the same manner as described above. After the second plating film 38 is formed, the substrate is transferred to another plating apparatus, and a third plating film 44 is formed in the plating apparatus.

Hereinafter, a plating apparatus will be described in accordance with an embodiment of the present invention, which is suitable for performing plating such as copper on a surface of a substrate (such as a semiconductor wafer) to be plated to fill a copper Into a through hole having a diameter of, for example, 1 micrometer to 100 micrometers.

Figure 18 is a front elevational view, in elevation, of a plating apparatus 370 in accordance with an embodiment of the present invention. The plating apparatus 370 can be used in place of the plating apparatus 170 of the plating facility in FIG.

As shown in FIG. 18, the plating apparatus 370 includes a plating plate for receiving The plating tank 386 of the solution Q is coated so that the substrate W is vertically immersed in the plating tank 386; the substrate holder 160 (shown in FIG. 6) receives the substrate W and seals the periphery of the substrate W to the surface of the substrate W. (The surface to be plated) is exposed. In this embodiment, the plating solution contains at least one of an organic sulfide, a polymer, and an organic nitride in addition to copper ions, a supplementary electrolyte, and a halogen ion. Preferably, sulfuric acid is used as a supplementary electrolyte, and chloride ions are used as a halogen ion.

The overflow tank 400 is disposed around the upper portion of the plating tank 386 for receiving the plating solution Q overflowing to the edge of the plating tank 386. One end of the circulation duct 404 provided with the pump 402 is connected to the bottom of the overflow tank 400, and the other end of the circulation duct 404 is connected to the plating solution supply input hole 386a installed at the bottom of the plating tank 386. The plating solution Q in the overflow tank 400 is returned to the plating tank 386 by priming the pump 402. A tempering unit 406 located at a downstream position of the pump 402 and a filter 408 are inserted into the circulation duct 404 for controlling the temperature of the plating solution Q, and the filter 408 is used to The foreign matter in the plating solution is filtered off. A bottom plate 410 having a large number of plating solution via holes is disposed at the bottom of the plating tank 386.

The anode 412 is received by the anode holder 414 and vertically mounted in the plating tank 386. The shape of the anode 412 is a circular shape corresponding to the shape of the substrate W. When the plating solution Q is injected into the plating tank 386, the anode 412 is immersed in the plating solution Q, and faces the substrate which is received by the substrate holder 160 and disposed at a predetermined position in the plating tank 386. W. In addition, in the plating tank 386, an adjustment plate for adjusting the potential distribution in the plating tank 386 418 (which is composed of a dielectric material) is disposed between the anode 412 and the substrate holder 160. The substrate holder 160 is disposed at a predetermined position in the plating tank 386. The lower end of the adjustment plate 418 can reach the bottom plate 410.

A plurality of stirring blades 420 vertically extending and juxtaposed in the same interval are disposed between the adjusting plate 418 and the substrate holder 160 disposed at a predetermined position in the plating groove 386, and the stirring paddle 420 is parallel to the substrate. The surface of W reciprocates back and forth to agitate the plating solution Q between the substrate holder 160 and the adjustment plate 418. These stirring blades 420 constitute a plating solution stirring member.

The bubble supply member 422 is disposed at the bottom of the plating tank 386 at a position above the bottom plate 410 and near the lower end of the stirring paddle 420 (plating solution stirring member), especially near the lower end of the agitating paddles 420. However, it is slightly closer to the position of the substrate W. As shown in Figs. 19 and 20, the bubble supply member 422 is constituted by a hollow line 424 having a plurality of penetration holes 424a arranged in two rows at a predetermined pitch P along the longitudinal direction thereof. The bubble supply member 422 extends approximately the total width of the plating groove 386. The diameter d ₀ of the penetration holes 424a is, for example, 0.1 mm to 2.0 mm. The penetration holes 424a are installed in the lower half of the hollow line 424 such that the plating solution Q in the plating tank 386 does not flow into the hollow line 424.

The hollow line 424 (to establish the bubble supply member 422) can also be configured such that the through holes 424a are located adjacent the plating solution via holes of the bottom plate 410 of the plating tank 386. This allows the bubble to flow along the surface of the substrate W efficiently with the plating solution.

The bubble supply member 422 supplies air bubbles such as air or nitrogen to the surface at a supply rate of, for example, 0.1 liter/minute to 10 liters/minute (preferably 1 liter/minute to 5 liter/minute) during the plating process. The plating solution Q on the surface of the substrate W (the surface to be plated) is such that bubbles flow along the entire surface of the substrate W, and the bubble supply member 422 is constituted by a hollow line 424 from which the substrate W is 160 is taken and arranged at a predetermined location. Although not illustrated, in order to allow bubbles to flow efficiently along the entire surface of the substrate W, the substrate holder 160 may be inclined at an angle of 0.1 to 1.0 with respect to the vertical direction.

As shown in Figs. 21 and 22, a porous body 426 (which may be a porous plastic or ceramic body) may be used as the bubble supply member 422. The structure of the bubble supply member 422 can be simplified by using the porous body 426.

The plating apparatus 370 is provided with a plating power source 430. During the plating process, the anode of the plating power source 430 is connected to the anode 412 through a wire, and the cathode is connected to the substrate W through a wire.

During operation of the plating apparatus 370, a predetermined amount of plating solution Q is first injected into the plating tank 386. Next, the substrate holder 160 receiving the substrate W is lowered to dispose the substrate W at a predetermined position in the plating tank 386, and immersed in the plating solution Q in the plating tank 386, and the anode of the plating power source 430 A cathode is connected to the anode 412 and the substrate W to perform plating of the surface of the substrate W, respectively. During the plating process, the agitating paddle 420 reciprocates parallel to the substrate W, thereby agitating the plating solution Q between the adjusting plate 418 and the substrate W, while the bubble supplying member 422 is, for example, 0.1 liter/minute. Up to 10 liters / minute (preferably 1 liter / minute to The supply rate of 5 liters/min is supplied to a plating solution Q such as air or nitrogen bubbles to the surface of the substrate W (the surface to be plated). The pump 402 of the circulation line 404 can be driven to circulate the plating solution Q while cooling the plating solution Q to be maintained at a predetermined temperature.

After a predetermined time elapses, the voltage applied between the anode 412 and the substrate W, the reciprocating movement of the stirring paddle 420, and the bubble supply from the bubble supply member 422 are all stopped to end the plating.

The plating apparatus 370 can be used in place of the plating apparatus 170 of FIG. For example, a substrate W as shown in FIG. 3B is provided, and the substrate W is formed by depositing an insulating film 512 (for example, cerium oxide) on the surface of the substrate 510 (for example, germanium) to form a plurality of upward openings. A via hole 514; a barrier layer 516 (for example, TaN) is formed on the entire surface; and a seed layer 518 as a plated (copper) supply layer is formed on the surface of the barrier layer 516. As shown in FIG. 3C, the substrate W is subjected to a series of plating process steps as in the previous embodiment, whereby copper is filled into the via holes 514 and a copper film 520 is deposited on the insulating film 512.

In the above embodiment, the pre-processing device 126 is disposed in the plating space 116, and the substrate holder 160 receives the substrate while pre-processing the substrate, but the pre-processing device may be disposed in the cleaning space. In 114, and after the pre-treatment, a series of plating process steps are performed while the substrate is supported by the substrate holder.

Example 1

The test sample is formed by a physical vapor deposition (PVD) on a germanium wafer substrate to a thickness of 100 nanometers (nm). A titanium (Ti) barrier layer having a plurality of holes (through holes) having a diameter of 20 μm and a depth of 50 μm, and then forming a copper seed layer having a thickness of 500 nm on the barrier layer by PVD. Copper plating of the surface of the test sample (substrate) was carried out in the following plating conditions using a plating apparatus as shown in Fig. 18 and a copper sulfate plating solution having the following composition:

Plating solution composition

Copper sulfate pentahydate: 200 g / liter

Sulfuric acid: 50 g / liter

Chlorine: 60 mg / liter

Additives: sulfides, polymers, nitrides, and the like.

Plating conditions

Current density: 5 mA / cm ^ 2

Plating time: 30 minutes

Stirring paddle moving speed (average): 200 mm / sec

Number of paddles: 5

Circulating flow rate: 2 liters / minute

Bubble supply: gas is supplied by a plurality of 0.5 mm penetration holes of the hollow line at a rate of 2 liters per minute

Example 2

The same test sample was subjected to electroplating in the same manner as in Example 1, but a bubble supply member composed of a porous body (porous ceramic body) as shown in Figs. 21 and 22 was used. The porous body was supplied with a gas at a rate of 150 ml/min.

Comparative example 1

The same test sample was electroplated in the same manner as in Example 1 except that the plating solution was not stirred with a stirring paddle.

Control example 2

The same test sample was plated in the same manner as in Example 1 except that the plating solution was not stirred with a stirring paddle, and the gas was supplied at a rate of 150 ml/min.

The portions of the holes were cut out from the individual test samples having the copper plated films obtained in Examples 1, 2 and Comparative Examples 1, 2, and the cut surfaces were observed. The individual plated films are evaluated from the viewpoint of the parameters described in Fig. 23: hole diameter d; thickness t of the plated film formed on the outer surface of the test sample on the outer surface of the holes; and evaluation index t/ d. The results are shown in Table 1 below. An evaluation index value of less than 0.5 indicates that plating is preferentially performed in the holes, that is, the thickness of the copper plating film formed on the surface of the substrate and outside the hole filled with copper may be smaller than the radius of the holes.

As shown in the data in Table 1, the evaluation index of the samples of Examples 1 and 2 Significantly below 0.5, this means that the plated film will preferentially grow in the holes. Further, in the samples of Examples 1 and 2, the holes having a diameter of 20 μm and a depth of 50 μm were completely filled with copper without occurrence of defects such as voids. In contrast, the pores of the Comparative Example 1 and Comparative Example 2 samples were not completely filled with copper, that is, voids were formed in the embedded copper.

Fig. 24 shows the state of the plated film which was filled into the holes by electroplating in Example 1. It can be considered that the copper plating film is grown from the bottom of the holes immediately after the start of the plating; in the intermediate stage of the plating, the copper fills the holes half without defects; in a later plating stage, The holes are completely filled and no defects occur in the embedded copper film, and a thin copper film is formed on the surface of the test sample (substrate) outside the holes. Therefore, as shown in Fig. 24, the thickness T ₂ of the plated film formed on the surface of the test sample (substrate) outside the holes is significantly smaller than the diameter D _{2 of the} holes.

While the invention has been described by reference to the embodiments of the present invention, it is understood that the invention is not limited to the specific embodiments described above, but is intended to cover all possible variations and modifications within the inventive concept.

10‧‧‧Base

12‧‧‧through hole

14‧‧‧ seed layer

30‧‧‧resist pattern

32‧‧‧resistive opening

36‧‧‧Plated film

H‧‧‧height

W‧‧‧Substrate

Claims (12)

A method for forming a conductive structure, comprising the steps of: forming a conductive film on a whole surface of a substrate having a concave substrate for forming a via electrode using a three-dimensional deposition technique, the integral surface comprising a concave surface for the via electrode; a resist layer pattern is formed at a predetermined position on the conductive film; and when the conductive layer is used as a supply layer to perform the first plating condition, the substrate is immersed in the substrate to inhibit plating growth, and is added as an additive. First plating is performed by selecting a plating solution of an additive of a sulfide, a polymer or a nitride, and further filling a first plating film into the concave shape of the through-hole electrodes; After filling the first plating film, the substrate is immersed in a composition different from the first plating solution under the second plating condition using the conductive layer and the first plating film as a supply layer. Performing a second plating on the second plating solution, so that the second plating film can be grown on the conductive film exposed to the plurality of resist layer openings of the resist layer pattern and the first plating film. A second opening formed in the plated film having a flat surface of the. The method for forming a conductive structure according to claim 1, wherein the resist pattern has a height of 5 μm to 10 μm. The method for forming a conductive structure according to claim 1, wherein the first plating film and the second plating film are made of the same metal. A method of forming a conductive structure according to claim 1 of the patent scope, The first plated film and the second plated film are composed of copper or a copper alloy. The method for forming a conductive structure according to claim 1, wherein the second plating film is grown to a half height of the top of the resist pattern, and then the third plating is performed under the third plating condition to make the first A three-plated film is grown on the second plated film. The method of forming a conductive structure according to claim 5, wherein the third plated film is composed of a metal different from the first plated film and the second plated film. The method for forming a conductive structure according to claim 1, wherein the first plating film is filled in the concave shape of the through hole electrode, and the first plating film is terminated by the concave electrode. Before filling up. The method for forming a conductive structure according to claim 1, wherein the plating is performed at a second current value lower than the first current value before the concave electrodes are filled with the first plating film. The plating is carried out at least once for a predetermined period of time. A method of forming a conductive structure according to claim 1, wherein the plating solution is stirred while stirring, and the stirring paddle is moved substantially parallel to the surface of the substrate. A method of forming a conductive structure according to claim 1, wherein the plating solution is stirred while stirring, and the stirring paddle is rotated relative to the surface of the substrate. The method for forming a conductive structure according to claim 1, wherein the first plating is performed by immersing the substrate in a supply of nitrogen or air. The gas bubbles are caused to cause the supplied bubbles to flow along the entire surface of the substrate. The method of forming a conductive structure according to claim 1, wherein an average current value in the second plating condition is higher than a current value of the first plating condition.