KR20180109053A - Electroplating method - Google Patents

Abstract

A substrate having a through hole formed therein is immersed in a plating solution in a plating bath. A pair of anodes are arranged in the plating solution in the plating bath while respectively facing the front surface and the rear surface of the substrate in the plating solution. A plurality of plating treatments are performed on the front surface and the rear surface of the substrate for a predetermined time by supplying pulse currents respectively between the front surface of the substrate and one of the anodes facing the front surface of the substrate and between the rear surface of the substrate and another of the anodes facing the rear surface of the substrate. Currents are supplied in a direction facing plating currents in the plating treatments, respectively, between the front surface of the substrate and one of the anodes facing the front surface of the substrate, and between the rear surface of the substrate and another of the anodes facing the rear surface of the substrate, so that an inversion electrolytic treatment is performed on the front surface and the rear surface of the substrate between adjacent plating treatments.

Description

[0001] ELECTROPLATING METHOD [0002]

The present invention relates to an electroplating method for simultaneously plating both a front surface and a back surface of a substrate having a through-hole penetrating therethrough up and down, thereby filling a plating film of a metal such as copper in the through hole will be.

As a method for electrically connecting layers of a multilayer stack of substrates, such as semiconductor substrates, there is known a technique for forming through-vias of a plurality of metal vertically through the substrate. Generally, both the front side and the back side of the substrate having vertically penetrating through holes therein are simultaneously plated to fill the plating film of metal inside the through hole, thereby making vertical through-vias in the substrate do.

An electroplating apparatus for forming through-vias is known (see Japanese Patent No. 4138542). This electroplating apparatus includes a substrate holder for holding a substrate by exposing predetermined areas on its front and back surfaces while sealing peripheral areas around the predetermined areas, and a substrate holder for holding the substrate on the front and back sides of the substrate held by the substrate holder And a pair of oppositely disposed anodes. The substrate held by the substrate holder and the anodes are immersed in the plating liquid and then voltages are applied between the substrate and the anodes to simultaneously coat the front and back surfaces of the substrate formed with the vertical through holes therein , And a metal such as copper is embedded in the through hole.

Figs. 1A to 1D are drawings illustrating a process of filling a plated film in a through-hole formed in a substrate in order to form a through-via in a series of processing steps (see Japanese Patent No. 4248353).

1A, a vertical through hole 100a is formed on a base 100 formed therein, a barrier layer 102 made of Ti or the like, and a base layer 100 including inner surfaces of the through hole 100a. And a seed layer 104 as an electric feed layer covering all the surfaces of the substrate W. [ The front surface and the back surface of the substrate W are simultaneously plated to form a plated film of metal such as copper or the like on the front and back surfaces of the substrate W and in the through hole 100a as shown in FIG. (106). ≪ / RTI > The plated film 106 in the through hole 100a has the maximum thickness at its center along the in-depth direction. 1C, the plated film 106 is formed such that the tip portions of the layers of the plated film 106 grown from the wall surfaces of the plated-through hole 100a are aligned with the through- 0.0 > 100a < / RTI > Accordingly, a center portion along the depth direction of the through hole 100a is blocked by the plating film 106, and recesses 108 are formed above and below the closed region. The plating process may further be continued until the plating film 106 is filled in the recesses 108 until the plating film 106 is filled in the recesses 108, . In this manner, through-vias made of the plating film 106 are formed in the substrate W.

There has been proposed an electroplating method for filling through-holes formed in a substrate with a plated metal film (see Japanese Patent Application Laid-Open No. 2008-513985). According to this electroplating method, a forward pulsed current flows between the substrate as the cathode and the anode, and a reverse pulsed current flowing in the direction opposite to the forward pulse current is also supplied, And the anode, so that the center portion of the through hole is completely or almost completely filled.

In addition, a method for preventing the generation of whiskers during copper plating of a printed wiring substrate or the like has been proposed (see Japanese Patent Laid-Open Publication No. 2010-95775). According to this method, the DC power supply for applying the DC voltage between the cathode and the anode has a polarity that is reversible. The printed wiring board has a normal electrolysis cycle in which the printed wiring board serves as a cathode and a reverse electrolysis cycle in which the printed wiring board serves as an anode, alternately under a normal DC voltage and an inverted DC voltage, Electroplating alternately with a reverse electrolyzing cycle.

In order to form through-vias on the substrate in the form of a plating film without defects such as voids, the center portion of the through hole 100a is formed on the plating film 106 as shown in Figs. 1A to 1D And then the plating film is preferentially grown at the center of the through hole along the depth direction until the plating treatment is further continued. However, it is practically difficult to shorten the time required for satisfying these ideal requirements and at the same time filling the plated film efficiently into the through-hole to perform the plating treatment. In other words, conventional electroplating processes have made it difficult to achieve both an ideal filling in the through-hole of the plated film and an effective filling in the through-hole of the plated film by increasing the average plating current at the time of plating.

The present invention has been devised in view of the above circumstances. Therefore, the average plating current at the time of plating is increased to efficiently charge the plated film in the plated-through hole, thereby shortening the time required for performing the plating treatment, and further, the electroplating for the ideal filling in the plated- And a method thereof.

According to an aspect of the present invention, there is provided a method of manufacturing a plating bath, the method including: immersing a substrate having a through hole therein in a plating solution in a plating bath; Disposing a pair of anodes in the plating liquid in the plating tank opposite to the front and back surfaces of the substrate in the plating liquid; A pulse current is supplied between the front surface of the substrate and the anode opposed to the front surface of the substrate and between the rear surface of the substrate and the other anode opposite to the rear surface of the substrate, And performing a plurality of plating processes respectively for a period of time of the plating process; And between the front surface of the substrate and the anode opposed to the front surface of the substrate and between the rear surface of the substrate and the other anode opposite to the back surface of the substrate respectively in a direction opposite to the pulse current in the plating process And applying a current between the adjacent ones of the plating processes to perform a reverse electrolyzing process on the front and back surfaces of the substrate.

A pulse current is supplied between the front surface of the substrate and the anode opposed to the front surface of the substrate and between the rear surface of the substrate and the other anode opposite to the rear surface of the substrate, The time required for plating the substrate can be shortened by efficiently filling the plated film in the through holes with an increased average current value. The inverse electrolytic treatment performed between the plating processes is effective to dissolve the plating film deposited on the corners of the through hole. Therefore, the plating film is preferentially grown at the central portion of the through hole along the depth direction, so that the plating film can ideally be filled in the through hole.

In a preferred aspect of the present invention, each of the pulse currents includes a PR pulse current that alternately repeats a current flowing in a forward direction and a current flowing in a reverse direction.

The inverse electrolytic treatment is repeatedly performed between the plating processes using the PR pulse currents to prevent fine irregularities from being generated due to abnormal deposition on the microscopic surfaces of the plated film , And these fine irregularities prevent the formation of micro voids in the plated film.

In a preferred form of the invention, each of the pulse currents includes an on / off pulse current alternately repeating supply and stop of the plating current flowing in the forward direction.

Since the on / off pulse current provides non-plating times in which the plating current is not supplied in the plating process, the metal ion concentration in the plating solution within the through hole is restored at the non-plating time so that defects such as voids So that it is prevented from being formed in the plating film.

In a preferred form of the invention, each of the pulse currents comprises a composite pulse current represented by a combination of two pulse currents with different current values.

Since the plating film is continuously grown in the plating process with the composite pulse current, the plating film is prevented from dissolving into the plating solution during the plating process.

In a preferred form of the present invention, the plating processes together with the reverse electrolytic treatment are performed so as to gradually increase the average current density as the plating of the substrate proceeds.

As the plated film is gradually filled in the through hole during the plating process, the substantial aspect ratio of the through hole is changed. When the substantial aspect ratio of the through hole is changed, the plating film can be efficiently filled in the through hole in such a manner that the average current density is increased during the plating process to match the changed aspect ratio. As a result, the time required for plating the substrate can be further shortened.

In a preferred form of the present invention, the reverse electrolytic treatment is performed plural times before and after the normal electrolytic cycle in which the pulse current is supplied in the forward direction.

The reverse electrolytic treatment is carried out at a pulse pitch in the range of -30 to -40 ASD, for example, in the range of 0.1 to 10 ms, at a negative cathode current density. Depending on the aspect ratio of the through hole formed in the substrate, the plating film may not be ideally filled in the central portion of the through hole in the depth direction by an inverse electrolytic treatment at a pulse pitch shorter than 1.0 ms. However, when the inversion electrolytic treatment is repeatedly performed a plurality of times with a pulse pitch shorter than 1.0 ms before and after the normal electrolysis cycle in which the pulse current is supplied in the forward direction, the plating film can be ideally filled in the through hole.

According to the present invention, as described above, a pulse current is supplied between the front surface of the substrate and the anode opposed to the front surface of the substrate, and between the rear surface of the substrate and the other anode opposite to the rear surface of the substrate, respectively A plurality of plating processes are respectively performed on the front surface and the back surface of the substrate for a predetermined time. Accordingly, it is possible to efficiently fill the plated film in the through hole with the increased average current value, thereby shortening the time required for plating the substrate. The inverse electrolytic treatment performed between the plating processes is effective to dissolve the plating films deposited on the corners of the through holes. Therefore, the plating film is preferentially grown at the central portion of the through hole along the depth direction, so that the plating film can be ideally filled in the through hole.

These and other objects, features, and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the preferred embodiments of the invention.

FIGS. 1A to 1D illustrate a process of filling a plated film in a through-hole formed in a substrate and forming a through-via in the substrate in a series of processing steps;
Fig. 2 is a longitudinal front view schematically showing an electroplating apparatus used for carrying out the electroplating method according to the present invention; Fig.
Fig. 3 is a front view of the substrate holder of the electroplating apparatus shown in Fig. 2; Fig.
Fig. 4 is a plan view of the substrate holder of the electroplating apparatus shown in Fig. 2; Fig.
Fig. 5 is a bottom view of the substrate holder of the electroplating apparatus shown in Fig. 2; Fig.
FIG. 6 is a cross-sectional view taken along the line KK in FIG. 3; FIG.
Figure 7 is a view of the substrate holder seen along the arrow A in Figure 6;
Figure 8 is a view of the substrate holder seen along the arrow B in Figure 6;
Figure 9 is a view of the substrate holder seen along arrow C in Figure 6;
10 is a cross-sectional view taken along line DD of FIG. 7;
11 is a cross-sectional view taken along the line EE of Fig. 7;
12 is a cross-sectional view taken along the FF line of Fig. 3;
13 is a sectional view taken along the line GG in Fig. 7;
14 is a cross-sectional view taken along the line HH in Fig. 8;
Fig. 15 is a front view of an anode holder holding an insoluble anode therein, of the electroplating apparatus shown in Fig. 2; Fig.
16 is a cross-sectional view of the anode holder holding the insoluble anode therein, of the electroplating apparatus shown in Fig. 2;
17 is an enlarged cross-sectional view of the main part of another substrate holder;
18 is an enlarged sectional view of the main part of the substrate holder shown in Fig. 17;
19 is an enlarged sectional view of the main part of the substrate holder shown in Fig. 17;
20 is a graph showing the relationship between the cathode current density and time in an example of the plating current supplied between the substrate surface and the anode;
21 is an enlarged partial sectional view showing a manner in which a plating film is preferentially grown at a center portion of a through hole along the depth direction when an inversion electrolytic treatment is performed after plating treatment;
22 is an enlarged partial sectional view schematically showing a manner in which fine irregularities are generated by abnormal deposition on micro-surfaces of a plated film during plating processing;
23 is a graph showing the relationship between the cathode current density and time in another example of the plating current supplied between the substrate surface and the anode;
24A and 24B are enlarged partial sectional views schematically showing how plating films embedded in the through holes are excessively dissolved into the plating liquid until voids are finally formed in the plating film;
25 is a graph showing the relationship between the cathode current density and time in another example of the plating current supplied between the substrate surface and the anode;
26 is a graph showing the relationship between the cathode current density and time in still another example of the plating current supplied between the substrate surface and the anode;
27 is a graph showing the relationship between the cathode current density and time in another example of the plating current supplied between the substrate surface and the anode;
28 is a graph showing the relationship between the cathode current density and time in still another example of the plating current supplied between the substrate surface and the anode;
29 is a graph showing the relationship between the cathode current density and time in still another example of the plating current supplied between the substrate surface and the anode;
30 is a graph showing the relationship between the cathode current density and time in another example of the plating current supplied between the substrate surface and the anode;
31 is a graph showing the relationship between the cathode current density and time in still another example of the plating current supplied between the substrate surface and the anode; And
32 is a graph showing the relationship between the cathode current density and time in still another example of the plating current supplied between the substrate surface and the anode.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. 2 is a longitudinal elevation view schematically showing an electroplating apparatus 50 used for carrying out the electroplating method according to the present invention. 2, the electroplating apparatus 50 includes a plating tank 51 for holding a plating liquid Q therein, and a plating tank 51 which is vertically suspended in the plating liquid Q, W). ≪ / RTI > The plating liquid Q immersed in the substrate holder 10 has a surface level L at the upper end of the plating bath 51, as shown in FIG. On the respective opposing surfaces of the substrate W held by the substrate holder 10, that is to say the plating vessel 51 opposed to the front and back surfaces, on the respective anode holders 58 Two insoluble anodes 52 are disposed. 3, the substrate holder 10 includes a first holding member 11 having a circular hole 11a formed therein and a second holding member 12 having a circular hole 12a formed therein, . The first holding member 11 and the second holding member 12 serve to hold the substrate W therebetween. The insoluble anodes 52 are substantially identical in size to the circular holes 11a and 12a in the first and second holding members 11 and 12 and are circular in shape.

Two control plates 60 made of an insulating material are disposed between the respective insoluble anodes 52 in the substrate holder 10 and the plating tank 51. The throttle plates 60 are formed with respective circular holes having similar shapes to the circular holes 11a and 12a in the first and second holding members 11 and 12, respectively. The insoluble anodes 52 are electrically connected to respective conductors 61a extending from respective terminals of each of the plating power sources 53 capable of changing a direction and a current value to which current is supplied . The plating power source 53 has other terminals electrically connected to the respective leads 61 Ib connected to the terminal plates 27 and 28 (see FIG. 3) of the substrate holder 10, respectively. The plating power supply 53 is also electrically connected to a control unit 59 which controls the plating power supplies 53 individually.

Two stirring paddles 62 are disposed between the respective control plates 60 in the plating bath 51 and the substrate W held by the substrate holder 10. The agitating paddles 62 are movable back and forth in parallel to the substrate W held by the substrate holder 10 to agitate the plating liquid Q. The electroplating apparatus 50 also includes an outer tank 57 disposed around the plating tank 51 for holding the plating liquid Q overflowing from the plating tank 51. [ The plating liquid Q overflowed from the plating tank 51 into the outer tank 57 is discharged from the bottom thereof through the constant temperature unit 55 and the filter 56 by the plating liquid circulation pump 54 to the plating tank 51 ). ≪ / RTI >

3 is a front view of the substrate holder 10. Fig. 4 is a plan view of the substrate holder 10. Fig. 5 is a bottom view of the substrate holder 10. Fig. 6 is a cross-sectional view taken along the line K-K in Fig. Figure 7 is a view of the substrate holder 10 as viewed along arrow A in Figure 6. 8 is a view of the substrate holder 10 viewed along arrow B in Fig. FIG. 9 is a view of the substrate holder 10 viewed along arrow C in FIG. 10 is a cross-sectional view taken along the line D-D in Fig. 11 is a cross-sectional view taken along the line E-E in Fig. 12 is a cross-sectional view taken along the line F-F in Fig. 13 is a cross-sectional view taken along the line G-G in Fig. 14 is a cross-sectional view taken along the line H-H in Fig.

3, each plate-shaped first holding member 11 and second holding member 12 of the substrate holder 10 are pivotally coupled to each other by a hinge mechanism 13, Respectively. The hinge mechanism 13 includes two hooks 13-1 of synthetic resin, for example HTPVC, fixed to the second holding member 12. [ The hooks 13-1 are movably supported at an angle on the lower end of the first holding member 11 by a hook pin 13-2 made of stainless steel such as SUS 303 . The first holding member 11 is made of a synthetic resin such as HTPVC, and is substantially pentagonal. The circular hole 11a is formed in the center of the first holding member 11 as shown in Fig. As shown in FIG. 3, the upper end of the first holding member 11 is integrally formed with a T-shaped hanger 14 made of synthetic resin such as HTPVC. The second holding member 12 is made of a synthetic resin such as HTPVC, and is substantially pentagonal. The circular hole 12a is formed in the second holding member 12 in the center direction.

When the first holding member 11 and the second holding member 12 are turned to each other in a superposed relation about the hinge mechanism 13, that is, when the substrate holder 10 is closed The first holding member 11 and the second holding member 12 are held together by the left and right clamps 15 and 16. The left and right clamps 15 and 16 each made of a synthetic resin such as HTPVC can be used to hold the side marginal edges of the first holding member 11 and the second holding member 12, And has respective grooves 15a, 16a for receiving therein. The left and right clamps 15 and 16 have bottom ends movably supported at respective angles on the lower ends of the opposite sides of the first holding member 11 by respective fins 17 and 18.

7, a seal ring 19 is mounted on one surface of the first holding member 11 facing the second holding member 12, . A seal ring 20 is mounted on one surface of the second holding member 12 facing the first holding member 11 and extends around the hole 12a have. The seal rings 19 and 20 are made of rubber, for example, silicone rubber. An O-ring 29 is mounted on the surface of the second holding member 12 facing the first holding member 11 and extends around the seal ring 20. [

The seal rings 19 and 20, each having a rectangular cross section, have respective ridges 19a and 20a extending along the inner peripheral edges thereof and projecting radially inwardly therefrom. When the first holding member 11 and the second holding member 12 are superimposed on each other with the substrate W interposed therebetween, the protrusions 19a and 20a contact the respective surfaces of the substrate W (29), which is located radially outwardly of the holes (11a, 12a) and the O-ring (29) Thereby forming a watertight space. 7 and 10, on the surface of the first holding member 11, which faces the second holding member 12 in the radial direction outside the hole 11a, the substrate W Eight substrate guide pins 21 for positioning are mounted and protrude through the seal ring 19. [

7, 11 and 12, six conductive plates (not shown) are formed on the surface of the first holding member 11 facing the second holding member 12 around the hole 11a, 22 are mounted. 11, three of the six conductive plates 22 are electrically connected to one of the surfaces of the substrate W, for example, the front surface of the substrate W via conductive pins 23 (See Figs. 1A to 1D). 12, the remaining three conductive plates 22 are held in electrical contact with the seed layer 104 on the other surface of the substrate W, for example, on the backside thereof, through the conductive pins 23.

Three conductive plates 22 held in electrical contact with one of the surfaces of the substrate W, e.g., the front surface of the seed layer 104, are electrically connected through a wire slot 25 (see FIG. 13) 27b, and 27c (see FIG. 4) provided on the terminal plate 27 of the hanger 14 through insulated covered wires 26. The electrode terminals 27a, 27b, and 27c are electrically connected to each other. The other three conductive plates 22, which are held in electrical contact with the seed layer 104 on the other surface of the substrate W, for example on the rear surface, 28b, and 28c (see FIG. 4) provided on the other terminal board 28 of the hanger 14 through the sheathed wires 26. The electrode terminals 28a, 28b, and 28c are electrically connected to each other. As shown in FIGS. 7 and 13, the insulating sheaths 26 are held in place by wire holders 30 made of a synthetic resin, such as PVC.

The substrate holder 10 operates as follows; When the first holding member 11 and the second holding member 12 are separated from each other and turned around the hinge mechanism 13, that is, when the substrate holder 10 is opened, Is disposed in an area on the first holding member 11 surrounded by the eight substrate guide pins 21. [ The substrate (W) is now located in place on the first holding member (11). The first holding member 11 and the second holding member 12 are turned about the hinge mechanism 13 toward each other. That is, the substrate holder 10 is closed. The left and right clamps 15 and 16 are formed such that the side edge edges of the first holding member 11 and the second holding member 12 are formed in the respective grooves 15a and 16a of the left and right clamps 15 and 16 (17, 18) until they are inserted into the pins (17, 18). A substrate W positioned in place on the first holding member 11 is now held between the first holding member 11 and the second holding member 12.

The protrusions 19a and 20a of the seal rings 19 and 20 and the O-ring 29 form a watertight space without the plating liquid Q therebetween. The outer peripheral edge region of the substrate W positioned radially outwardly of the protrusions 19a and 20a is located in the watertight space and the first holding member 11 and the second holding member 12 are positioned in the watertight space, The surface areas of the opposite surfaces of the substrate W coextensive with the holes 11a and 12a of the substrate 11 are exposed to the holes 11a and 12a. Three of the six conductive plates 22 held in electrical contact with the seed layer 104 on one of the surfaces of the substrate W are electrically connected to the electrode terminals 27 provided on the terminal plate 27 of the hanger 14. [ And the other three conductive plates 22 electrically connected to the hatches 27a, 27b and 27c and held in electrical contact with the seed layer 104 on the other surfaces of the substrate W, Are electrically connected to the electrode terminals 28a, 28b, and 28c provided on the terminal plate 28 of the battery pack 20.

Fig. 15 is a front view of the anode holder 58 holding the insoluble anode 52 of the electroplating apparatus shown in Fig. 2, and Fig. 16 is a sectional view of Fig. In the above embodiment, in order to prevent the anodes from dissolving by the additive (s) of the plating solution, the insoluble anodes 52 each comprising an anode body of titanium coated with iridium oxide are used.

15 and 16, each of the anode holders 58 includes a holder body 70 formed therein with a central hole 70a, a plurality of anode holders 70 disposed on the back side of the holder body 70, A closing plate 72 for closing the hole 70a is disposed inside the central hole 70a of the holder main body 70 and the insoluble anode 52 is held on the surface of the insoluble anode 52, A circular support plate 74 positioned within the central aperture 70a and an annular anode mask 76 disposed on the front surface of the holder body 70 in surrounding relation to the central aperture 70a. The support plate 74 is provided therein with a passage 74a for housing therein a conductive plate 78 electrically connected to the conductive line 61a extending from the plating power source 53 therein. The conductive plate 78 extends to a central region of the support plate 74, to which the conductive plate 78 is electrically connected to the insoluble anode 52.

A separating membrane 80 in the form of a neutral membrane is disposed in a covering relationship with the surface of the insoluble anode 58 located in the central hole 70a of the holder main body 70. The diaphragm 80 has its peripheral edge gripped in place by the holder body 70 and the anode mask 76 and is fastened to the holder body 70. The anode mask 76 is fastened to the holder body 70 by a screw 82 and the closing plate 72 is also fastened to the holder body 70 by screws.

When the anode holder 58 is immersed in the plating solution, the plating solution Q enters the gap between the insoluble anode 52 and the support plate 74 inside the central hole 70a of the holder main body 70.

The additive to be added to the plating solution (Q) includes a component for promoting the formation of monovalent copper, which is used for oxidative decomposition of other additives Thereby impairing the function of other additives. As a result, soluble anodes can not be used. When insoluble anodes are used, the insoluble anodes generate oxygen gas in the vicinity thereof, and a part of the generated oxygen gas is dissolved into the plating liquid Q, thereby increasing the concentration of dissolved oxygen. The increased concentration of dissolved oxygen tends to cause oxidative degradation of the additives. Therefore, in order to prevent the components of the additives near the substrate W from adversely affecting even in the case of undergoing oxidative decomposition in the vicinity of the insoluble anode 52, the diaphragm 80 in the form of a neutral membrane, Is preferably arranged in a covering relationship with the surface of the base member (52).

Further, in order to prevent the concentration of dissolved oxygen from rising excessively on the side of the insoluble anode 52, for example, air or nitrogen supplied through an aeration tube (not shown) It is preferable that the plating liquid Q is bubbled or aerated in the vicinity thereof.

The surface of the insoluble anode 52 held by the anode holder 58 is covered with the diaphragm 80 and the diaphragm 80 is held by the substrate holder 10, Oxygen gas is generated in the vicinity of the insoluble anode 52 when the plating liquid Q is bubbled or aerated so that the insoluble anode 52 is exposed to the inside of the plating liquid It is possible to prevent the concentration of dissolved oxygen in the plating liquid Q from rising.

The thus configured electroplating apparatus 50 operates as follows: the substrate holder 10 holding the substrate W on which its front and back surfaces are exposed is exposed to one of the surfaces of the substrate W, The plating liquid is supplied to the plating liquid Q in the plating tank 51 such that the front surface opposes one of the insoluble anodes 52 and the other surface of the substrate W faces the remaining insoluble anode 52, Respectively. Between the front surface of the substrate W and the insoluble anode 52 opposed to the front surface of the substrate W and between the rear surface of the substrate W and the back surface of the substrate W, The plating power supplies 53 are supplied to the plating unit 53 to simultaneously apply the plating currents controlled by the control unit 59 between the front surface and the back surface of the substrate W at the same time. When the front and rear surfaces of the substrate W are plated, the stirring paddles 62 are moved back and forth in parallel with the substrate W to agitate the plating liquid Q, if necessary. In this manner, as shown in FIGS. 1A to 1D, a plating film 106 is grown in the through hole 100a formed in the substrate W.

Figures 17-19 show enlarged cross-sectional views of another substrate holder taken at different cross-sectional planes, respectively. The substrate holder shown in Figs. 17 to 19 differs from the above-described substrate holder as follows: As shown in Fig. 17, the substrate holder includes conductive pins 22 and 23 shown in Figs. 11 and 12, (90, 92) having respective proximal ends fastened to the first holding member (11) and the second holding member (12). When the substrate W is held by the first holding member 11 and the second holding member 12, the distal free ends of the elastic conductive plates 90, (See Figs. 1A to 1D) on the front and rear surfaces of the substrate W, and is elastically held against the front and back surfaces of the substrate W, respectively.

18 and 19, the substrate holder also includes sealing rings 94 and 96 for holding the seal rings 19 and 20, respectively. The sealing rings 94 and 96 are fastened to the first holding member 11 and the second holding member 12, respectively. The seal ring holders 94 and 96 are provided with alternate guide teeth 97 and 98 for positioning the substrate W in place of the substrate guide pins 21 shown in FIGS. ). ≪ / RTI > The guide teeth 97, 98 are disposed at respective positions along the circumferential direction of the seal ring holders 94, 96. The guide teeth 97, 98 have respective tapered surfaces 97a, 98a on their inner peripheral surfaces near their free ends. When the substrate W is held by the first holding member 11 and the second holding member 12, the outer peripheral edge of the substrate W contacts the tapered surfaces 97a and 98a And is guided to position the substrate W.

20 shows the relationship between the cathode current density and the time in an example of the plating current supplied between the insoluble anode 52 arranged in opposing relation to the surface of the substrate W and the surface of the substrate W Show. The plating current supplied between the backside of the substrate W and the insoluble anode 52 opposing the backside of the substrate W is insoluble in the opposite direction to the front side of the substrate W and the front side of the substrate W, And held in synchronization with the plating current supplied between the anode (52). However, since these plating currents need not be synchronized with each other, the present invention should not be limited by whether or not the plating currents are synchronized with each other. The plating current supplied between the front surface of the substrate W and the insoluble anode 52 disposed in the opposite relation thereto will be described with reference to FIG.

20, a plating process A for supplying a pulse current between the surface of the substrate W and the insoluble anode 52 to perform plating for a predetermined time on the surface of the substrate W, An inverse electrolytic treatment B in which a current is supplied in a direction opposite to a current supplied in the plating process A is alternately repeated between the surface of the substrate W and the insoluble anode 52. [ The predetermined time at which the plating process A is performed is, for example, in the range of 50 to 100 ms, and the predetermined time at which the inverse electrolytic process B is performed is, for example, 0.1 to 10 ms, or preferably 0.5 To 1 ms.

As indicated by the imaginary lines in Fig. 20, for example, after the inverse electrolysis process B and before the plating process A, no current is supplied between the surface of the substrate W and the insoluble anode 52, for example, A quiescent period C of 0.05 ms may be inserted. The dwell period C may uniformize the distribution of the metal ions in the plating liquid Q in the through hole to efficiently fill the plated film in the through hole. In each of the other examples described below, the idle period C may be inserted for its advantages.

In the example shown in Figure 20, for example 1 to 3 ASD (A / dm ²⁾ has a positive cathode current density D ₁ in the range of, normally the plating current to flow in forward direction, that is, the pulse pitch P ₁ in the plating direction electrolytic Cycles and a negative pulse current density D ₂ in the range of, for example, -0.05 to -4 ASD, and alternately repeating the inverse electrolysis cycles in which the plating current flows in the reverse direction at the pulse pitch P ₂ , Processing A is carried out. The pulse pitch P ₂ in the inversion electrolysis cycles of the PR pulse current is, for example, 0.5 ms. The inverse electrolytic treatment B has a single pulse at a pulse pitch P ₃ in the range of 0.1 to 10 ms, preferably 0.5 to 1 ms, with a negative cathode current density D ₃ , for example, in the range of -30 to -40 ASD .

For example, since the inverse electrolytic treatment B having the negative cathode current density D ₃ in the range of -30 to -40 ASD is carried out after the plating process A, as shown by the imaginary lines in FIG. 21, The plated film 106a which is likely to be deposited on the corners is dissolved into the plating liquid Q so that the plated film Q is preferentially deposited on the central portion of the through hole 100a along the depth direction, 106).

As schematically shown in Fig. 22, in the plating process, the fine irregularities 106b are likely to be generated due to abnormal deposition on the micro-surfaces of the plated film 106. [ However, the fine irregularity part (106b) are, it is prevented in accordance with the example shown in Figure 20, for example with a -0.05 to -4 ASD negative cathode current density in the range of D ₂ generated by the reverse electrolysis cycle. Otherwise, the fine irregularities 106b due to abnormal deposition are bonded to each other to form fine voids in the plated film.

23 shows the relationship between the cathode current density and the time in another example of the plating current supplied between the surface of the substrate W and the insoluble anode 52 disposed in an opposing relation to the surface of the substrate W Show. The example shown in FIG. 23 is an example in which two pulses are applied at a pulse pitch P ₄ before and after a normal electrolysis cycle in which the plating current is applied in the forward direction, for example, in the range of 0.1 to 10 ms, preferably 0.5 to 1.0 ms Which is different from the example shown in Fig. 20 in that an inverse electrolytic treatment B ₁ is carried out.

As shown in FIG. 20, an inverse electrolytic treatment B having a negative cathode current density D ₃ in the range of -30 to -40 ASD is carried out with a single pulse at a pulse pitch P ₃ in the range of 0.1 to 10 ms. If the pulse pitch P ₃ is greater than 1 ms, the plating film 106 is excessively dissolved into the plating liquid, as schematically shown in FIG. 24A, to form the over-dissolved regions 112. As shown in FIG. 24B, the over-melted regions 112 are easily formed in the plated film 106 embedded in the through-hole 110a, and the cat- And has its open ends closed. Therefore, the pulse pitch P ₃ should preferably be in the range of 0.1 to 1.0 ms, and more preferably in the range of 0.5 to 1.0 ms.

However, in accordance with the aspect ratio of the through hole formed in the substrate W, the plating film is ideally embedded in the central portion of the through hole along the depth direction in accordance with the reverse electrolytic treatment using a single pulse having a pulse pitch shorter than 1.0 ms It may not be possible to perform an ideal embedding process for the data. As shown in FIG. 23, the inverse electrolytic process B _{1, which} is carried out by applying two pulses at a pulse pitch P ₄ shorter than 1.0 ms each, allows the plating film to ideally be filled in these through-holes.

25 shows a relationship between the cathode current density and time in another example of the plating current supplied between the surface of the substrate W and the insoluble anode 52 disposed in an opposing relation to the surface of the substrate W Lt; / RTI > The example shown in Fig. 25 shows three different plating processes, that is, the plating film 106 in the through hole 100a is formed along the depth direction of the through hole 100a, as shown in Figs. 1A to 1C. (The first plating process) A ₁ , Fig. 1C and Fig. 1D in the first region until substantially joined at the central portion of the through hole 100a in the through hole 100a, A plating process (second plating process) A ₂ in the second region for embedding the plating film 106 to a predetermined thickness, and a plating process (second plating process) for reducing the risk of pinch-off after the stage shown in FIG. And a plating process (third plating process) A ₃ in the third area.

25, the first plating process A ₁ , the second plating process A _2, and the third plating process A ₃ are performed once before and after the reverse electrolytic treatment B (see FIG. 20), respectively. However, each of the first plating process A ₁ , the second plating process A _2, and the third plating process A ₃ is actually performed a plurality of times before and after the inverse electrolytic process B. This also applies to the other examples described below.

In the example shown in FIG. 25, the first plating process A ₁ , the second plating process A _2, and the third plating process A ₃ alternately repeat the supply and stop of the plating current flowing in the forward direction, that is, the plating direction , And has a positive cathode current density D ₁ , for example, in the range of 1 to 3 ASD. The on / off pulse current in the first plating process A ₁ has a pulse pitch P ₅ (P ₅ < P ₆ ) shorter than the pulse pitch P ₆ of the on / off pulse current in the second plating process A ₂ , The pulse pitch P ₆ of the on / off pulse current in the second plating process A ₂ is shorter than the pulse pitch P ₇ of the on / off pulse current in the third plating process A ₃ (P ₆ <P ₇ ). The on / off pulse currents in the first, second and third plating processes A ₁ , A ₂ and A ₃ are the same as the respective downtime pitches P ₈ , P ₉ , P ₁₀ (P ₈ = P ₉ = P ₁₀ ). The average cathode current density may increase stepwise or the average cathode current density may gradually increase linearly.

Since the on / off pulse currents provide non-plating times that do not supply a plating current in the entire plating process, the metal ion concentration in the plating solution in the through hole is restored at the non-plating times, And the like are prevented from being formed in the plating film. As the plated film is gradually filled in the through hole during the plating process, the substantial aspect ratio of the through hole is changed. When the substantial aspect ratio of the through hole is changed, the plating film can be efficiently filled into the through hole by increasing the average cathode current density during the plating process to match the changing substantial aspect ratio of the through hole. As a result, the time required for plating the substrate can be further shortened.

It is generally well known that the plating current density is increased stepwise as the plating process proceeds. However, it is difficult to inhibit the formation of monovalent copper over the entire range of plating current densities from a low plating current density to a high plating current density. According to this example, since the cathode current density has a constant peak value, the generation of monovalent copper is suppressed, so that deterioration of the plating solution can be prevented.

26 shows the relationship between the cathode current density and time in another example of the plating current supplied between the surface of the substrate W and the insoluble anode 52 disposed in an opposing relation to the surface of the substrate W Show. The example shown in Fig. 26 is an example in which, instead of the inverse electrolytic processing B shown in Fig. 25 having a single pulse at a pulse pitch P ₃ in the range of 0.1 to 10 ms, preferably 0.5 to 1 ms, Is different from the example shown in Fig. 25 in that the inverse electrolytic treatment B ₁ is performed by applying two pulses at a pulse pitch P ₄ in the range of 0.1 to 10 ms, preferably 0.5 to 1.0 ms, for example.

27 shows a relationship between the cathode current density and time in another example of the plating current supplied between the surface of the substrate W and the insoluble anode 52 disposed in an opposing relation to the surface of the substrate W Show. 27, the first, second and third plating processes A ₁ , A ₂ and A ₃ have the same respective processing times, and on / off pulses in the first plating process A ₁ current of the second has a plating short pulse pitch P ₅ than on / off pulses of current pulse pitch P ₆ in the _{a 2 (P 5 <P 6} ), the second on / off pulse in the plating process a ₂ of the current pulse pitch P ₆ is the third plating process a in the _third on / in the off pulse current pulse pitch P is shorter than _{7 (P 6 <P 7)} , the first on / off pulse current in the plating a ₁ downtime pitch P ₈ is the second plating treatment longer than downtime pitch P ₉ in the on / off pulse current in the _{a 2 (P 8> P 9} ), the second on / off pulse in the plating process a ₂ current of downtime pitch P ₉ is the third plating process a is longer than the on / off pulse downtime pitch P ₁₀ of the current in the _third (P _9> P ₁₀₎ Figure 25 in that it is It is different from the example shown. Therefore, the average cathode current density increases stepwise.

28 shows a relationship between the cathode current density and time in another example of the plating current supplied between the surface of the substrate W and the insoluble anode 52 arranged in an opposing relation to the surface of the substrate W Show. The example shown in Fig. 28 is a diagram for supplying an on / off pulse current by repeating the supply and stop of the plating current flowing in the forward direction having the positive cathode current density D ₁ in the range of 1 to 3 ASD, A first plating current having a positive cathode current density D ₁ in the range of, for example, 1 to 3 ASD and a positive plating current density D ₄ in the range of, for example, 0.1 to 0.5 ASD And a composite pulse power source for supplying a second plating current is used.

The composite pulse power source is used to continuously supply a weak current in the range of, for example, 0.1 to 0.5 ASD rather than stopping the supply of the plating current, so that the plating film continues to grow during the plating process. Therefore, the plating film is prevented from being dissolved in the plating liquid during the plating treatment.

29 shows the relationship between the cathode current density and the time in another example of the plating current supplied between the surface of the substrate W and the insoluble anode 52 disposed in an opposing relation to the surface of the substrate W Show. The example shown in FIG. 29 is a diagram illustrating normal electrolytic cycles having a positive cathode current density D ₁ , for example in the range of 1 to 3 ASD, and a reverse electrolysis cycle having a negative cathode current density D ₂ in the range of -0.05 to -4 ASD, 25 in which supplying and stopping of the plating current having the positive cathode current density in the range of, for example, 1 to 3 ASD is repeated in that the PR pulse current is supplied by repeating electrolysis cycles to supply the supplied on / off pulse current .

30 shows a relationship between the cathode current density and time in another example of the plating current supplied between the surface of the substrate W and the insoluble anode 52 arranged in an opposing relation to the surface of the substrate W Show. The example shown in FIG. 30 provides a DC plating current having a positive cathode current density D ₁ in the range of, for example, 1 to 3 ASDs, so that the first, second and third plating treatments A ₁ , A ₂ , A ₃ The first, second, and third plating processes A ₁ , A ₂ , and A ₃ have respective processing times that are getting gradually longer in this order, unlike the example shown in FIG.

Depending on the aspect ratio of the through holes, the structure of the underlayer of the plating, the properties of the plating liquid, etc., it may not be necessary to provide a dwell time between the reverse electrolytic treatments. If the dwell time is not required, a plating current may be supplied between the surface of the substrate W and the insoluble anode 52 to achieve the relationship between the cathode current density and the time shown in Fig. 30 , The time required for performing the plating process can be shortened, and the plating film can be efficiently filled in the through hole.

31 shows a relationship between the cathode current density and time in still another example of the plating current supplied between the insoluble anode 52 arranged in an opposing relation to the surface of the substrate W and the surface of the substrate W Lt; / RTI &gt; The example shown in Fig. 31 shows the risk of pinch-off when the plating film 106 is embedded in the recessed portion 108 in the through hole 100a to a predetermined thickness, for example, as shown in Fig. Is reduced, and the plating process A ₄ carried out by supplying a DC plating current having a positive cathode current density D ₁ in the range of, for example, 1 to 3 ASD leads to an inverse electrolytic process B, Do. 1D, it is almost completed to embed the plating film into the through hole 100a of the substrate W, and the dimples remaining on the surface of the substrate W are removed dimples are finally charged. At this time, it is not always necessary to supply the DC plating current to equalize the cathode current density with the previous pulse peak current density, but the DC plating current may be supplied to make the cathode current density higher than the previous pulse peak current density, The time required for performing the plating process can be shortened.

32 shows the relationship between the cathode current density and time in another example of the plating current supplied between the surface of the substrate W and the insoluble anode 52 arranged in an opposing relation to the surface of the substrate W Show. The example shown in FIG. 32 is performed by supplying a DC plating current having a positive cathode current density D ₁ in the range of, for example, 1 to 3 ASD to perform the third plating treatment A ₃ , thereby shortening the time required to perform the plating treatment Which is different from the example shown in Fig.

While certain preferred embodiments of the invention have been shown and described in detail, it should be apparent that various changes and modifications may be made therein without departing from the scope of the appended claims.

Claims (7)

1. A substrate holder for electroplating a substrate,
A first holding member having a first conductive pin contactable with a first surface of the substrate,
A second holding member having a second conductive pin contactable with a second surface of the substrate opposite to the first surface;
A first seal ring mounted on the first holding member,
A second seal ring mounted on the second holding member,
And a sealing ring disposed outside the first seal ring and the second seal ring,
Wherein the first holding member and the second holding member are configured to be openable and closable,
The first seal ring has a first protrusion that can contact the first surface of the substrate,
The second seal ring has a second projection portion that can contact the second surface of the substrate,
Wherein when the substrate is electroplated, a closed space is formed in which the first projecting portion, the second projecting portion, and the conductive liquid surrounded by the sealing ring do not penetrate,
Wherein the first conductive pin and the second conductive pin are located in the closed space,
Wherein the first conductive pin and the second conductive pin are located between the first and second protrusions and the sealing ring. The method according to claim 1,
Wherein the first seal ring and the second seal ring have a rectangular cross section and the first protrusion is located on the inner circumferential side of the first seal ring and the second protrusion is located on the inner circumferential side of the second seal ring And the substrate holder. The method according to claim 1,
And a plurality of substrate guide pins for positioning the substrate are provided on a surface of the first holding member opposite to the second holding member. The method according to claim 1,
A first electrode terminal electrically connected to the first conductive pin,
And a second electrode terminal electrically connected to the second conductive pin. The method according to claim 1,
The first holding member may include a first conductive plate made of a leaf spring capable of contacting the first surface of the substrate,
Wherein the second holding member has a second conductive plate formed of a leaf spring capable of contacting the second surface of the substrate instead of the second conductive pin. The method according to claim 1,
Further comprising a clamp for holding the first holding member and the second holding member while the first holding member and the second holding member are stacked. The method according to claim 1,
Wherein the first holding member and the second holding member are provided with a sealing ring holder for holding the first sealing ring and the second sealing ring respectively and the sealing ring holder is provided with a plurality of guides Wherein the substrate holder comprises a plurality of teeth.

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